11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namespace.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * (C) Copyright Al Viro 2000, 2001 51da177e4SLinus Torvalds * Released under GPL v2. 61da177e4SLinus Torvalds * 71da177e4SLinus Torvalds * Based on code from fs/super.c, copyright Linus Torvalds and others. 81da177e4SLinus Torvalds * Heavily rewritten. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds #include <linux/syscalls.h> 121da177e4SLinus Torvalds #include <linux/slab.h> 131da177e4SLinus Torvalds #include <linux/sched.h> 141da177e4SLinus Torvalds #include <linux/smp_lock.h> 151da177e4SLinus Torvalds #include <linux/init.h> 1615a67dd8SRandy Dunlap #include <linux/kernel.h> 171da177e4SLinus Torvalds #include <linux/acct.h> 1816f7e0feSRandy Dunlap #include <linux/capability.h> 193d733633SDave Hansen #include <linux/cpumask.h> 201da177e4SLinus Torvalds #include <linux/module.h> 21f20a9eadSAndrew Morton #include <linux/sysfs.h> 221da177e4SLinus Torvalds #include <linux/seq_file.h> 236b3286edSKirill Korotaev #include <linux/mnt_namespace.h> 241da177e4SLinus Torvalds #include <linux/namei.h> 251da177e4SLinus Torvalds #include <linux/security.h> 261da177e4SLinus Torvalds #include <linux/mount.h> 2707f3f05cSDavid Howells #include <linux/ramfs.h> 2813f14b4dSEric Dumazet #include <linux/log2.h> 2973cd49ecSMiklos Szeredi #include <linux/idr.h> 305ad4e53bSAl Viro #include <linux/fs_struct.h> 311da177e4SLinus Torvalds #include <asm/uaccess.h> 321da177e4SLinus Torvalds #include <asm/unistd.h> 3307b20889SRam Pai #include "pnode.h" 34948730b0SAdrian Bunk #include "internal.h" 351da177e4SLinus Torvalds 3613f14b4dSEric Dumazet #define HASH_SHIFT ilog2(PAGE_SIZE / sizeof(struct list_head)) 3713f14b4dSEric Dumazet #define HASH_SIZE (1UL << HASH_SHIFT) 3813f14b4dSEric Dumazet 391da177e4SLinus Torvalds /* spinlock for vfsmount related operations, inplace of dcache_lock */ 401da177e4SLinus Torvalds __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); 411da177e4SLinus Torvalds 425addc5ddSAl Viro static int event; 4373cd49ecSMiklos Szeredi static DEFINE_IDA(mnt_id_ida); 44719f5d7fSMiklos Szeredi static DEFINE_IDA(mnt_group_ida); 455addc5ddSAl Viro 46fa3536ccSEric Dumazet static struct list_head *mount_hashtable __read_mostly; 47e18b890bSChristoph Lameter static struct kmem_cache *mnt_cache __read_mostly; 48390c6843SRam Pai static struct rw_semaphore namespace_sem; 491da177e4SLinus Torvalds 50f87fd4c2SMiklos Szeredi /* /sys/fs */ 5100d26666SGreg Kroah-Hartman struct kobject *fs_kobj; 5200d26666SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(fs_kobj); 53f87fd4c2SMiklos Szeredi 541da177e4SLinus Torvalds static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) 551da177e4SLinus Torvalds { 561da177e4SLinus Torvalds unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); 571da177e4SLinus Torvalds tmp += ((unsigned long)dentry / L1_CACHE_BYTES); 5813f14b4dSEric Dumazet tmp = tmp + (tmp >> HASH_SHIFT); 5913f14b4dSEric Dumazet return tmp & (HASH_SIZE - 1); 601da177e4SLinus Torvalds } 611da177e4SLinus Torvalds 623d733633SDave Hansen #define MNT_WRITER_UNDERFLOW_LIMIT -(1<<16) 633d733633SDave Hansen 6473cd49ecSMiklos Szeredi /* allocation is serialized by namespace_sem */ 6573cd49ecSMiklos Szeredi static int mnt_alloc_id(struct vfsmount *mnt) 6673cd49ecSMiklos Szeredi { 6773cd49ecSMiklos Szeredi int res; 6873cd49ecSMiklos Szeredi 6973cd49ecSMiklos Szeredi retry: 7073cd49ecSMiklos Szeredi ida_pre_get(&mnt_id_ida, GFP_KERNEL); 7173cd49ecSMiklos Szeredi spin_lock(&vfsmount_lock); 7273cd49ecSMiklos Szeredi res = ida_get_new(&mnt_id_ida, &mnt->mnt_id); 7373cd49ecSMiklos Szeredi spin_unlock(&vfsmount_lock); 7473cd49ecSMiklos Szeredi if (res == -EAGAIN) 7573cd49ecSMiklos Szeredi goto retry; 7673cd49ecSMiklos Szeredi 7773cd49ecSMiklos Szeredi return res; 7873cd49ecSMiklos Szeredi } 7973cd49ecSMiklos Szeredi 8073cd49ecSMiklos Szeredi static void mnt_free_id(struct vfsmount *mnt) 8173cd49ecSMiklos Szeredi { 8273cd49ecSMiklos Szeredi spin_lock(&vfsmount_lock); 8373cd49ecSMiklos Szeredi ida_remove(&mnt_id_ida, mnt->mnt_id); 8473cd49ecSMiklos Szeredi spin_unlock(&vfsmount_lock); 8573cd49ecSMiklos Szeredi } 8673cd49ecSMiklos Szeredi 87719f5d7fSMiklos Szeredi /* 88719f5d7fSMiklos Szeredi * Allocate a new peer group ID 89719f5d7fSMiklos Szeredi * 90719f5d7fSMiklos Szeredi * mnt_group_ida is protected by namespace_sem 91719f5d7fSMiklos Szeredi */ 92719f5d7fSMiklos Szeredi static int mnt_alloc_group_id(struct vfsmount *mnt) 93719f5d7fSMiklos Szeredi { 94719f5d7fSMiklos Szeredi if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL)) 95719f5d7fSMiklos Szeredi return -ENOMEM; 96719f5d7fSMiklos Szeredi 97719f5d7fSMiklos Szeredi return ida_get_new_above(&mnt_group_ida, 1, &mnt->mnt_group_id); 98719f5d7fSMiklos Szeredi } 99719f5d7fSMiklos Szeredi 100719f5d7fSMiklos Szeredi /* 101719f5d7fSMiklos Szeredi * Release a peer group ID 102719f5d7fSMiklos Szeredi */ 103719f5d7fSMiklos Szeredi void mnt_release_group_id(struct vfsmount *mnt) 104719f5d7fSMiklos Szeredi { 105719f5d7fSMiklos Szeredi ida_remove(&mnt_group_ida, mnt->mnt_group_id); 106719f5d7fSMiklos Szeredi mnt->mnt_group_id = 0; 107719f5d7fSMiklos Szeredi } 108719f5d7fSMiklos Szeredi 1091da177e4SLinus Torvalds struct vfsmount *alloc_vfsmnt(const char *name) 1101da177e4SLinus Torvalds { 111c3762229SRobert P. J. Day struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); 1121da177e4SLinus Torvalds if (mnt) { 11373cd49ecSMiklos Szeredi int err; 11473cd49ecSMiklos Szeredi 11573cd49ecSMiklos Szeredi err = mnt_alloc_id(mnt); 11688b38782SLi Zefan if (err) 11788b38782SLi Zefan goto out_free_cache; 11888b38782SLi Zefan 11988b38782SLi Zefan if (name) { 12088b38782SLi Zefan mnt->mnt_devname = kstrdup(name, GFP_KERNEL); 12188b38782SLi Zefan if (!mnt->mnt_devname) 12288b38782SLi Zefan goto out_free_id; 12373cd49ecSMiklos Szeredi } 12473cd49ecSMiklos Szeredi 1251da177e4SLinus Torvalds atomic_set(&mnt->mnt_count, 1); 1261da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_hash); 1271da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_child); 1281da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_mounts); 1291da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_list); 13055e700b9SMiklos Szeredi INIT_LIST_HEAD(&mnt->mnt_expire); 13103e06e68SRam Pai INIT_LIST_HEAD(&mnt->mnt_share); 132a58b0eb8SRam Pai INIT_LIST_HEAD(&mnt->mnt_slave_list); 133a58b0eb8SRam Pai INIT_LIST_HEAD(&mnt->mnt_slave); 134d3ef3d73Snpiggin@suse.de #ifdef CONFIG_SMP 135d3ef3d73Snpiggin@suse.de mnt->mnt_writers = alloc_percpu(int); 136d3ef3d73Snpiggin@suse.de if (!mnt->mnt_writers) 137d3ef3d73Snpiggin@suse.de goto out_free_devname; 138d3ef3d73Snpiggin@suse.de #else 139d3ef3d73Snpiggin@suse.de mnt->mnt_writers = 0; 140d3ef3d73Snpiggin@suse.de #endif 1411da177e4SLinus Torvalds } 1421da177e4SLinus Torvalds return mnt; 14388b38782SLi Zefan 144d3ef3d73Snpiggin@suse.de #ifdef CONFIG_SMP 145d3ef3d73Snpiggin@suse.de out_free_devname: 146d3ef3d73Snpiggin@suse.de kfree(mnt->mnt_devname); 147d3ef3d73Snpiggin@suse.de #endif 14888b38782SLi Zefan out_free_id: 14988b38782SLi Zefan mnt_free_id(mnt); 15088b38782SLi Zefan out_free_cache: 15188b38782SLi Zefan kmem_cache_free(mnt_cache, mnt); 15288b38782SLi Zefan return NULL; 1531da177e4SLinus Torvalds } 1541da177e4SLinus Torvalds 1558366025eSDave Hansen /* 1568366025eSDave Hansen * Most r/o checks on a fs are for operations that take 1578366025eSDave Hansen * discrete amounts of time, like a write() or unlink(). 1588366025eSDave Hansen * We must keep track of when those operations start 1598366025eSDave Hansen * (for permission checks) and when they end, so that 1608366025eSDave Hansen * we can determine when writes are able to occur to 1618366025eSDave Hansen * a filesystem. 1628366025eSDave Hansen */ 1633d733633SDave Hansen /* 1643d733633SDave Hansen * __mnt_is_readonly: check whether a mount is read-only 1653d733633SDave Hansen * @mnt: the mount to check for its write status 1663d733633SDave Hansen * 1673d733633SDave Hansen * This shouldn't be used directly ouside of the VFS. 1683d733633SDave Hansen * It does not guarantee that the filesystem will stay 1693d733633SDave Hansen * r/w, just that it is right *now*. This can not and 1703d733633SDave Hansen * should not be used in place of IS_RDONLY(inode). 1713d733633SDave Hansen * mnt_want/drop_write() will _keep_ the filesystem 1723d733633SDave Hansen * r/w. 1733d733633SDave Hansen */ 1743d733633SDave Hansen int __mnt_is_readonly(struct vfsmount *mnt) 1753d733633SDave Hansen { 1762e4b7fcdSDave Hansen if (mnt->mnt_flags & MNT_READONLY) 1772e4b7fcdSDave Hansen return 1; 1782e4b7fcdSDave Hansen if (mnt->mnt_sb->s_flags & MS_RDONLY) 1792e4b7fcdSDave Hansen return 1; 1802e4b7fcdSDave Hansen return 0; 1813d733633SDave Hansen } 1823d733633SDave Hansen EXPORT_SYMBOL_GPL(__mnt_is_readonly); 1833d733633SDave Hansen 184d3ef3d73Snpiggin@suse.de static inline void inc_mnt_writers(struct vfsmount *mnt) 1853d733633SDave Hansen { 186d3ef3d73Snpiggin@suse.de #ifdef CONFIG_SMP 187d3ef3d73Snpiggin@suse.de (*per_cpu_ptr(mnt->mnt_writers, smp_processor_id()))++; 188d3ef3d73Snpiggin@suse.de #else 189d3ef3d73Snpiggin@suse.de mnt->mnt_writers++; 190d3ef3d73Snpiggin@suse.de #endif 1913d733633SDave Hansen } 1923d733633SDave Hansen 193d3ef3d73Snpiggin@suse.de static inline void dec_mnt_writers(struct vfsmount *mnt) 1943d733633SDave Hansen { 195d3ef3d73Snpiggin@suse.de #ifdef CONFIG_SMP 196d3ef3d73Snpiggin@suse.de (*per_cpu_ptr(mnt->mnt_writers, smp_processor_id()))--; 197d3ef3d73Snpiggin@suse.de #else 198d3ef3d73Snpiggin@suse.de mnt->mnt_writers--; 199d3ef3d73Snpiggin@suse.de #endif 200d3ef3d73Snpiggin@suse.de } 201d3ef3d73Snpiggin@suse.de 202d3ef3d73Snpiggin@suse.de static unsigned int count_mnt_writers(struct vfsmount *mnt) 203d3ef3d73Snpiggin@suse.de { 204d3ef3d73Snpiggin@suse.de #ifdef CONFIG_SMP 205d3ef3d73Snpiggin@suse.de unsigned int count = 0; 2063d733633SDave Hansen int cpu; 2073d733633SDave Hansen 2083d733633SDave Hansen for_each_possible_cpu(cpu) { 209d3ef3d73Snpiggin@suse.de count += *per_cpu_ptr(mnt->mnt_writers, cpu); 2103d733633SDave Hansen } 2113d733633SDave Hansen 212d3ef3d73Snpiggin@suse.de return count; 213d3ef3d73Snpiggin@suse.de #else 214d3ef3d73Snpiggin@suse.de return mnt->mnt_writers; 215d3ef3d73Snpiggin@suse.de #endif 2163d733633SDave Hansen } 2173d733633SDave Hansen 2183d733633SDave Hansen /* 2193d733633SDave Hansen * Most r/o checks on a fs are for operations that take 2203d733633SDave Hansen * discrete amounts of time, like a write() or unlink(). 2213d733633SDave Hansen * We must keep track of when those operations start 2223d733633SDave Hansen * (for permission checks) and when they end, so that 2233d733633SDave Hansen * we can determine when writes are able to occur to 2243d733633SDave Hansen * a filesystem. 2253d733633SDave Hansen */ 2268366025eSDave Hansen /** 2278366025eSDave Hansen * mnt_want_write - get write access to a mount 2288366025eSDave Hansen * @mnt: the mount on which to take a write 2298366025eSDave Hansen * 2308366025eSDave Hansen * This tells the low-level filesystem that a write is 2318366025eSDave Hansen * about to be performed to it, and makes sure that 2328366025eSDave Hansen * writes are allowed before returning success. When 2338366025eSDave Hansen * the write operation is finished, mnt_drop_write() 2348366025eSDave Hansen * must be called. This is effectively a refcount. 2358366025eSDave Hansen */ 2368366025eSDave Hansen int mnt_want_write(struct vfsmount *mnt) 2378366025eSDave Hansen { 2383d733633SDave Hansen int ret = 0; 2393d733633SDave Hansen 240d3ef3d73Snpiggin@suse.de preempt_disable(); 241d3ef3d73Snpiggin@suse.de inc_mnt_writers(mnt); 242d3ef3d73Snpiggin@suse.de /* 243d3ef3d73Snpiggin@suse.de * The store to inc_mnt_writers must be visible before we pass 244d3ef3d73Snpiggin@suse.de * MNT_WRITE_HOLD loop below, so that the slowpath can see our 245d3ef3d73Snpiggin@suse.de * incremented count after it has set MNT_WRITE_HOLD. 246d3ef3d73Snpiggin@suse.de */ 247d3ef3d73Snpiggin@suse.de smp_mb(); 248d3ef3d73Snpiggin@suse.de while (mnt->mnt_flags & MNT_WRITE_HOLD) 249d3ef3d73Snpiggin@suse.de cpu_relax(); 250d3ef3d73Snpiggin@suse.de /* 251d3ef3d73Snpiggin@suse.de * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will 252d3ef3d73Snpiggin@suse.de * be set to match its requirements. So we must not load that until 253d3ef3d73Snpiggin@suse.de * MNT_WRITE_HOLD is cleared. 254d3ef3d73Snpiggin@suse.de */ 255d3ef3d73Snpiggin@suse.de smp_rmb(); 2563d733633SDave Hansen if (__mnt_is_readonly(mnt)) { 257d3ef3d73Snpiggin@suse.de dec_mnt_writers(mnt); 2583d733633SDave Hansen ret = -EROFS; 2593d733633SDave Hansen goto out; 2603d733633SDave Hansen } 2613d733633SDave Hansen out: 262d3ef3d73Snpiggin@suse.de preempt_enable(); 2633d733633SDave Hansen return ret; 2648366025eSDave Hansen } 2658366025eSDave Hansen EXPORT_SYMBOL_GPL(mnt_want_write); 2668366025eSDave Hansen 2678366025eSDave Hansen /** 2688366025eSDave Hansen * mnt_drop_write - give up write access to a mount 2698366025eSDave Hansen * @mnt: the mount on which to give up write access 2708366025eSDave Hansen * 2718366025eSDave Hansen * Tells the low-level filesystem that we are done 2728366025eSDave Hansen * performing writes to it. Must be matched with 2738366025eSDave Hansen * mnt_want_write() call above. 2748366025eSDave Hansen */ 2758366025eSDave Hansen void mnt_drop_write(struct vfsmount *mnt) 2768366025eSDave Hansen { 277d3ef3d73Snpiggin@suse.de preempt_disable(); 278d3ef3d73Snpiggin@suse.de dec_mnt_writers(mnt); 279d3ef3d73Snpiggin@suse.de preempt_enable(); 2808366025eSDave Hansen } 2818366025eSDave Hansen EXPORT_SYMBOL_GPL(mnt_drop_write); 2828366025eSDave Hansen 2832e4b7fcdSDave Hansen static int mnt_make_readonly(struct vfsmount *mnt) 2848366025eSDave Hansen { 2853d733633SDave Hansen int ret = 0; 2863d733633SDave Hansen 2872e4b7fcdSDave Hansen spin_lock(&vfsmount_lock); 288d3ef3d73Snpiggin@suse.de mnt->mnt_flags |= MNT_WRITE_HOLD; 289d3ef3d73Snpiggin@suse.de /* 290d3ef3d73Snpiggin@suse.de * After storing MNT_WRITE_HOLD, we'll read the counters. This store 291d3ef3d73Snpiggin@suse.de * should be visible before we do. 292d3ef3d73Snpiggin@suse.de */ 293d3ef3d73Snpiggin@suse.de smp_mb(); 294d3ef3d73Snpiggin@suse.de 295d3ef3d73Snpiggin@suse.de /* 296d3ef3d73Snpiggin@suse.de * With writers on hold, if this value is zero, then there are 297d3ef3d73Snpiggin@suse.de * definitely no active writers (although held writers may subsequently 298d3ef3d73Snpiggin@suse.de * increment the count, they'll have to wait, and decrement it after 299d3ef3d73Snpiggin@suse.de * seeing MNT_READONLY). 300d3ef3d73Snpiggin@suse.de * 301d3ef3d73Snpiggin@suse.de * It is OK to have counter incremented on one CPU and decremented on 302d3ef3d73Snpiggin@suse.de * another: the sum will add up correctly. The danger would be when we 303d3ef3d73Snpiggin@suse.de * sum up each counter, if we read a counter before it is incremented, 304d3ef3d73Snpiggin@suse.de * but then read another CPU's count which it has been subsequently 305d3ef3d73Snpiggin@suse.de * decremented from -- we would see more decrements than we should. 306d3ef3d73Snpiggin@suse.de * MNT_WRITE_HOLD protects against this scenario, because 307d3ef3d73Snpiggin@suse.de * mnt_want_write first increments count, then smp_mb, then spins on 308d3ef3d73Snpiggin@suse.de * MNT_WRITE_HOLD, so it can't be decremented by another CPU while 309d3ef3d73Snpiggin@suse.de * we're counting up here. 310d3ef3d73Snpiggin@suse.de */ 311d3ef3d73Snpiggin@suse.de if (count_mnt_writers(mnt) > 0) 312d3ef3d73Snpiggin@suse.de ret = -EBUSY; 313d3ef3d73Snpiggin@suse.de else 3142e4b7fcdSDave Hansen mnt->mnt_flags |= MNT_READONLY; 315d3ef3d73Snpiggin@suse.de /* 316d3ef3d73Snpiggin@suse.de * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers 317d3ef3d73Snpiggin@suse.de * that become unheld will see MNT_READONLY. 318d3ef3d73Snpiggin@suse.de */ 319d3ef3d73Snpiggin@suse.de smp_wmb(); 320d3ef3d73Snpiggin@suse.de mnt->mnt_flags &= ~MNT_WRITE_HOLD; 3212e4b7fcdSDave Hansen spin_unlock(&vfsmount_lock); 3223d733633SDave Hansen return ret; 3233d733633SDave Hansen } 3248366025eSDave Hansen 3252e4b7fcdSDave Hansen static void __mnt_unmake_readonly(struct vfsmount *mnt) 3262e4b7fcdSDave Hansen { 3272e4b7fcdSDave Hansen spin_lock(&vfsmount_lock); 3282e4b7fcdSDave Hansen mnt->mnt_flags &= ~MNT_READONLY; 3292e4b7fcdSDave Hansen spin_unlock(&vfsmount_lock); 3302e4b7fcdSDave Hansen } 3312e4b7fcdSDave Hansen 332a3ec947cSSukadev Bhattiprolu void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb) 333454e2398SDavid Howells { 334454e2398SDavid Howells mnt->mnt_sb = sb; 335454e2398SDavid Howells mnt->mnt_root = dget(sb->s_root); 336454e2398SDavid Howells } 337454e2398SDavid Howells 338454e2398SDavid Howells EXPORT_SYMBOL(simple_set_mnt); 339454e2398SDavid Howells 3401da177e4SLinus Torvalds void free_vfsmnt(struct vfsmount *mnt) 3411da177e4SLinus Torvalds { 3421da177e4SLinus Torvalds kfree(mnt->mnt_devname); 34373cd49ecSMiklos Szeredi mnt_free_id(mnt); 344d3ef3d73Snpiggin@suse.de #ifdef CONFIG_SMP 345d3ef3d73Snpiggin@suse.de free_percpu(mnt->mnt_writers); 346d3ef3d73Snpiggin@suse.de #endif 3471da177e4SLinus Torvalds kmem_cache_free(mnt_cache, mnt); 3481da177e4SLinus Torvalds } 3491da177e4SLinus Torvalds 3501da177e4SLinus Torvalds /* 351a05964f3SRam Pai * find the first or last mount at @dentry on vfsmount @mnt depending on 352a05964f3SRam Pai * @dir. If @dir is set return the first mount else return the last mount. 3531da177e4SLinus Torvalds */ 354a05964f3SRam Pai struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, 355a05964f3SRam Pai int dir) 3561da177e4SLinus Torvalds { 3571da177e4SLinus Torvalds struct list_head *head = mount_hashtable + hash(mnt, dentry); 3581da177e4SLinus Torvalds struct list_head *tmp = head; 3591da177e4SLinus Torvalds struct vfsmount *p, *found = NULL; 3601da177e4SLinus Torvalds 3611da177e4SLinus Torvalds for (;;) { 362a05964f3SRam Pai tmp = dir ? tmp->next : tmp->prev; 3631da177e4SLinus Torvalds p = NULL; 3641da177e4SLinus Torvalds if (tmp == head) 3651da177e4SLinus Torvalds break; 3661da177e4SLinus Torvalds p = list_entry(tmp, struct vfsmount, mnt_hash); 3671da177e4SLinus Torvalds if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) { 368a05964f3SRam Pai found = p; 3691da177e4SLinus Torvalds break; 3701da177e4SLinus Torvalds } 3711da177e4SLinus Torvalds } 3721da177e4SLinus Torvalds return found; 3731da177e4SLinus Torvalds } 3741da177e4SLinus Torvalds 375a05964f3SRam Pai /* 376a05964f3SRam Pai * lookup_mnt increments the ref count before returning 377a05964f3SRam Pai * the vfsmount struct. 378a05964f3SRam Pai */ 3791c755af4SAl Viro struct vfsmount *lookup_mnt(struct path *path) 380a05964f3SRam Pai { 381a05964f3SRam Pai struct vfsmount *child_mnt; 382a05964f3SRam Pai spin_lock(&vfsmount_lock); 3831c755af4SAl Viro if ((child_mnt = __lookup_mnt(path->mnt, path->dentry, 1))) 384a05964f3SRam Pai mntget(child_mnt); 385a05964f3SRam Pai spin_unlock(&vfsmount_lock); 386a05964f3SRam Pai return child_mnt; 387a05964f3SRam Pai } 388a05964f3SRam Pai 3891da177e4SLinus Torvalds static inline int check_mnt(struct vfsmount *mnt) 3901da177e4SLinus Torvalds { 3916b3286edSKirill Korotaev return mnt->mnt_ns == current->nsproxy->mnt_ns; 3921da177e4SLinus Torvalds } 3931da177e4SLinus Torvalds 3946b3286edSKirill Korotaev static void touch_mnt_namespace(struct mnt_namespace *ns) 3955addc5ddSAl Viro { 3965addc5ddSAl Viro if (ns) { 3975addc5ddSAl Viro ns->event = ++event; 3985addc5ddSAl Viro wake_up_interruptible(&ns->poll); 3995addc5ddSAl Viro } 4005addc5ddSAl Viro } 4015addc5ddSAl Viro 4026b3286edSKirill Korotaev static void __touch_mnt_namespace(struct mnt_namespace *ns) 4035addc5ddSAl Viro { 4045addc5ddSAl Viro if (ns && ns->event != event) { 4055addc5ddSAl Viro ns->event = event; 4065addc5ddSAl Viro wake_up_interruptible(&ns->poll); 4075addc5ddSAl Viro } 4085addc5ddSAl Viro } 4095addc5ddSAl Viro 4101a390689SAl Viro static void detach_mnt(struct vfsmount *mnt, struct path *old_path) 4111da177e4SLinus Torvalds { 4121a390689SAl Viro old_path->dentry = mnt->mnt_mountpoint; 4131a390689SAl Viro old_path->mnt = mnt->mnt_parent; 4141da177e4SLinus Torvalds mnt->mnt_parent = mnt; 4151da177e4SLinus Torvalds mnt->mnt_mountpoint = mnt->mnt_root; 4161da177e4SLinus Torvalds list_del_init(&mnt->mnt_child); 4171da177e4SLinus Torvalds list_del_init(&mnt->mnt_hash); 4181a390689SAl Viro old_path->dentry->d_mounted--; 4191da177e4SLinus Torvalds } 4201da177e4SLinus Torvalds 421b90fa9aeSRam Pai void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry, 422b90fa9aeSRam Pai struct vfsmount *child_mnt) 423b90fa9aeSRam Pai { 424b90fa9aeSRam Pai child_mnt->mnt_parent = mntget(mnt); 425b90fa9aeSRam Pai child_mnt->mnt_mountpoint = dget(dentry); 426b90fa9aeSRam Pai dentry->d_mounted++; 427b90fa9aeSRam Pai } 428b90fa9aeSRam Pai 4291a390689SAl Viro static void attach_mnt(struct vfsmount *mnt, struct path *path) 4301da177e4SLinus Torvalds { 4311a390689SAl Viro mnt_set_mountpoint(path->mnt, path->dentry, mnt); 432b90fa9aeSRam Pai list_add_tail(&mnt->mnt_hash, mount_hashtable + 4331a390689SAl Viro hash(path->mnt, path->dentry)); 4341a390689SAl Viro list_add_tail(&mnt->mnt_child, &path->mnt->mnt_mounts); 435b90fa9aeSRam Pai } 436b90fa9aeSRam Pai 437b90fa9aeSRam Pai /* 438b90fa9aeSRam Pai * the caller must hold vfsmount_lock 439b90fa9aeSRam Pai */ 440b90fa9aeSRam Pai static void commit_tree(struct vfsmount *mnt) 441b90fa9aeSRam Pai { 442b90fa9aeSRam Pai struct vfsmount *parent = mnt->mnt_parent; 443b90fa9aeSRam Pai struct vfsmount *m; 444b90fa9aeSRam Pai LIST_HEAD(head); 4456b3286edSKirill Korotaev struct mnt_namespace *n = parent->mnt_ns; 446b90fa9aeSRam Pai 447b90fa9aeSRam Pai BUG_ON(parent == mnt); 448b90fa9aeSRam Pai 449b90fa9aeSRam Pai list_add_tail(&head, &mnt->mnt_list); 450b90fa9aeSRam Pai list_for_each_entry(m, &head, mnt_list) 4516b3286edSKirill Korotaev m->mnt_ns = n; 452b90fa9aeSRam Pai list_splice(&head, n->list.prev); 453b90fa9aeSRam Pai 454b90fa9aeSRam Pai list_add_tail(&mnt->mnt_hash, mount_hashtable + 455b90fa9aeSRam Pai hash(parent, mnt->mnt_mountpoint)); 456b90fa9aeSRam Pai list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); 4576b3286edSKirill Korotaev touch_mnt_namespace(n); 4581da177e4SLinus Torvalds } 4591da177e4SLinus Torvalds 4601da177e4SLinus Torvalds static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root) 4611da177e4SLinus Torvalds { 4621da177e4SLinus Torvalds struct list_head *next = p->mnt_mounts.next; 4631da177e4SLinus Torvalds if (next == &p->mnt_mounts) { 4641da177e4SLinus Torvalds while (1) { 4651da177e4SLinus Torvalds if (p == root) 4661da177e4SLinus Torvalds return NULL; 4671da177e4SLinus Torvalds next = p->mnt_child.next; 4681da177e4SLinus Torvalds if (next != &p->mnt_parent->mnt_mounts) 4691da177e4SLinus Torvalds break; 4701da177e4SLinus Torvalds p = p->mnt_parent; 4711da177e4SLinus Torvalds } 4721da177e4SLinus Torvalds } 4731da177e4SLinus Torvalds return list_entry(next, struct vfsmount, mnt_child); 4741da177e4SLinus Torvalds } 4751da177e4SLinus Torvalds 4769676f0c6SRam Pai static struct vfsmount *skip_mnt_tree(struct vfsmount *p) 4779676f0c6SRam Pai { 4789676f0c6SRam Pai struct list_head *prev = p->mnt_mounts.prev; 4799676f0c6SRam Pai while (prev != &p->mnt_mounts) { 4809676f0c6SRam Pai p = list_entry(prev, struct vfsmount, mnt_child); 4819676f0c6SRam Pai prev = p->mnt_mounts.prev; 4829676f0c6SRam Pai } 4839676f0c6SRam Pai return p; 4849676f0c6SRam Pai } 4859676f0c6SRam Pai 48636341f64SRam Pai static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, 48736341f64SRam Pai int flag) 4881da177e4SLinus Torvalds { 4891da177e4SLinus Torvalds struct super_block *sb = old->mnt_sb; 4901da177e4SLinus Torvalds struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); 4911da177e4SLinus Torvalds 4921da177e4SLinus Torvalds if (mnt) { 493719f5d7fSMiklos Szeredi if (flag & (CL_SLAVE | CL_PRIVATE)) 494719f5d7fSMiklos Szeredi mnt->mnt_group_id = 0; /* not a peer of original */ 495719f5d7fSMiklos Szeredi else 496719f5d7fSMiklos Szeredi mnt->mnt_group_id = old->mnt_group_id; 497719f5d7fSMiklos Szeredi 498719f5d7fSMiklos Szeredi if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) { 499719f5d7fSMiklos Szeredi int err = mnt_alloc_group_id(mnt); 500719f5d7fSMiklos Szeredi if (err) 501719f5d7fSMiklos Szeredi goto out_free; 502719f5d7fSMiklos Szeredi } 503719f5d7fSMiklos Szeredi 5041da177e4SLinus Torvalds mnt->mnt_flags = old->mnt_flags; 5051da177e4SLinus Torvalds atomic_inc(&sb->s_active); 5061da177e4SLinus Torvalds mnt->mnt_sb = sb; 5071da177e4SLinus Torvalds mnt->mnt_root = dget(root); 5081da177e4SLinus Torvalds mnt->mnt_mountpoint = mnt->mnt_root; 5091da177e4SLinus Torvalds mnt->mnt_parent = mnt; 510b90fa9aeSRam Pai 5115afe0022SRam Pai if (flag & CL_SLAVE) { 5125afe0022SRam Pai list_add(&mnt->mnt_slave, &old->mnt_slave_list); 5135afe0022SRam Pai mnt->mnt_master = old; 5145afe0022SRam Pai CLEAR_MNT_SHARED(mnt); 5158aec0809SAl Viro } else if (!(flag & CL_PRIVATE)) { 516b90fa9aeSRam Pai if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old)) 517b90fa9aeSRam Pai list_add(&mnt->mnt_share, &old->mnt_share); 5185afe0022SRam Pai if (IS_MNT_SLAVE(old)) 5195afe0022SRam Pai list_add(&mnt->mnt_slave, &old->mnt_slave); 5205afe0022SRam Pai mnt->mnt_master = old->mnt_master; 5215afe0022SRam Pai } 522b90fa9aeSRam Pai if (flag & CL_MAKE_SHARED) 523b90fa9aeSRam Pai set_mnt_shared(mnt); 5241da177e4SLinus Torvalds 5251da177e4SLinus Torvalds /* stick the duplicate mount on the same expiry list 5261da177e4SLinus Torvalds * as the original if that was on one */ 52736341f64SRam Pai if (flag & CL_EXPIRE) { 52855e700b9SMiklos Szeredi if (!list_empty(&old->mnt_expire)) 52955e700b9SMiklos Szeredi list_add(&mnt->mnt_expire, &old->mnt_expire); 5301da177e4SLinus Torvalds } 53136341f64SRam Pai } 5321da177e4SLinus Torvalds return mnt; 533719f5d7fSMiklos Szeredi 534719f5d7fSMiklos Szeredi out_free: 535719f5d7fSMiklos Szeredi free_vfsmnt(mnt); 536719f5d7fSMiklos Szeredi return NULL; 5371da177e4SLinus Torvalds } 5381da177e4SLinus Torvalds 5397b7b1aceSAl Viro static inline void __mntput(struct vfsmount *mnt) 5401da177e4SLinus Torvalds { 5411da177e4SLinus Torvalds struct super_block *sb = mnt->mnt_sb; 5423d733633SDave Hansen /* 5433d733633SDave Hansen * This probably indicates that somebody messed 5443d733633SDave Hansen * up a mnt_want/drop_write() pair. If this 5453d733633SDave Hansen * happens, the filesystem was probably unable 5463d733633SDave Hansen * to make r/w->r/o transitions. 5473d733633SDave Hansen */ 548d3ef3d73Snpiggin@suse.de /* 549d3ef3d73Snpiggin@suse.de * atomic_dec_and_lock() used to deal with ->mnt_count decrements 550d3ef3d73Snpiggin@suse.de * provides barriers, so count_mnt_writers() below is safe. AV 551d3ef3d73Snpiggin@suse.de */ 552d3ef3d73Snpiggin@suse.de WARN_ON(count_mnt_writers(mnt)); 5531da177e4SLinus Torvalds dput(mnt->mnt_root); 5541da177e4SLinus Torvalds free_vfsmnt(mnt); 5551da177e4SLinus Torvalds deactivate_super(sb); 5561da177e4SLinus Torvalds } 5571da177e4SLinus Torvalds 5587b7b1aceSAl Viro void mntput_no_expire(struct vfsmount *mnt) 5597b7b1aceSAl Viro { 5607b7b1aceSAl Viro repeat: 5617b7b1aceSAl Viro if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) { 5627b7b1aceSAl Viro if (likely(!mnt->mnt_pinned)) { 5637b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 5647b7b1aceSAl Viro __mntput(mnt); 5657b7b1aceSAl Viro return; 5667b7b1aceSAl Viro } 5677b7b1aceSAl Viro atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count); 5687b7b1aceSAl Viro mnt->mnt_pinned = 0; 5697b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 5707b7b1aceSAl Viro acct_auto_close_mnt(mnt); 5717b7b1aceSAl Viro security_sb_umount_close(mnt); 5727b7b1aceSAl Viro goto repeat; 5737b7b1aceSAl Viro } 5747b7b1aceSAl Viro } 5757b7b1aceSAl Viro 5767b7b1aceSAl Viro EXPORT_SYMBOL(mntput_no_expire); 5777b7b1aceSAl Viro 5787b7b1aceSAl Viro void mnt_pin(struct vfsmount *mnt) 5797b7b1aceSAl Viro { 5807b7b1aceSAl Viro spin_lock(&vfsmount_lock); 5817b7b1aceSAl Viro mnt->mnt_pinned++; 5827b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 5837b7b1aceSAl Viro } 5847b7b1aceSAl Viro 5857b7b1aceSAl Viro EXPORT_SYMBOL(mnt_pin); 5867b7b1aceSAl Viro 5877b7b1aceSAl Viro void mnt_unpin(struct vfsmount *mnt) 5887b7b1aceSAl Viro { 5897b7b1aceSAl Viro spin_lock(&vfsmount_lock); 5907b7b1aceSAl Viro if (mnt->mnt_pinned) { 5917b7b1aceSAl Viro atomic_inc(&mnt->mnt_count); 5927b7b1aceSAl Viro mnt->mnt_pinned--; 5937b7b1aceSAl Viro } 5947b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 5957b7b1aceSAl Viro } 5967b7b1aceSAl Viro 5977b7b1aceSAl Viro EXPORT_SYMBOL(mnt_unpin); 5981da177e4SLinus Torvalds 599b3b304a2SMiklos Szeredi static inline void mangle(struct seq_file *m, const char *s) 600b3b304a2SMiklos Szeredi { 601b3b304a2SMiklos Szeredi seq_escape(m, s, " \t\n\\"); 602b3b304a2SMiklos Szeredi } 603b3b304a2SMiklos Szeredi 604b3b304a2SMiklos Szeredi /* 605b3b304a2SMiklos Szeredi * Simple .show_options callback for filesystems which don't want to 606b3b304a2SMiklos Szeredi * implement more complex mount option showing. 607b3b304a2SMiklos Szeredi * 608b3b304a2SMiklos Szeredi * See also save_mount_options(). 609b3b304a2SMiklos Szeredi */ 610b3b304a2SMiklos Szeredi int generic_show_options(struct seq_file *m, struct vfsmount *mnt) 611b3b304a2SMiklos Szeredi { 6122a32cebdSAl Viro const char *options; 6132a32cebdSAl Viro 6142a32cebdSAl Viro rcu_read_lock(); 6152a32cebdSAl Viro options = rcu_dereference(mnt->mnt_sb->s_options); 616b3b304a2SMiklos Szeredi 617b3b304a2SMiklos Szeredi if (options != NULL && options[0]) { 618b3b304a2SMiklos Szeredi seq_putc(m, ','); 619b3b304a2SMiklos Szeredi mangle(m, options); 620b3b304a2SMiklos Szeredi } 6212a32cebdSAl Viro rcu_read_unlock(); 622b3b304a2SMiklos Szeredi 623b3b304a2SMiklos Szeredi return 0; 624b3b304a2SMiklos Szeredi } 625b3b304a2SMiklos Szeredi EXPORT_SYMBOL(generic_show_options); 626b3b304a2SMiklos Szeredi 627b3b304a2SMiklos Szeredi /* 628b3b304a2SMiklos Szeredi * If filesystem uses generic_show_options(), this function should be 629b3b304a2SMiklos Szeredi * called from the fill_super() callback. 630b3b304a2SMiklos Szeredi * 631b3b304a2SMiklos Szeredi * The .remount_fs callback usually needs to be handled in a special 632b3b304a2SMiklos Szeredi * way, to make sure, that previous options are not overwritten if the 633b3b304a2SMiklos Szeredi * remount fails. 634b3b304a2SMiklos Szeredi * 635b3b304a2SMiklos Szeredi * Also note, that if the filesystem's .remount_fs function doesn't 636b3b304a2SMiklos Szeredi * reset all options to their default value, but changes only newly 637b3b304a2SMiklos Szeredi * given options, then the displayed options will not reflect reality 638b3b304a2SMiklos Szeredi * any more. 639b3b304a2SMiklos Szeredi */ 640b3b304a2SMiklos Szeredi void save_mount_options(struct super_block *sb, char *options) 641b3b304a2SMiklos Szeredi { 6422a32cebdSAl Viro BUG_ON(sb->s_options); 6432a32cebdSAl Viro rcu_assign_pointer(sb->s_options, kstrdup(options, GFP_KERNEL)); 644b3b304a2SMiklos Szeredi } 645b3b304a2SMiklos Szeredi EXPORT_SYMBOL(save_mount_options); 646b3b304a2SMiklos Szeredi 6472a32cebdSAl Viro void replace_mount_options(struct super_block *sb, char *options) 6482a32cebdSAl Viro { 6492a32cebdSAl Viro char *old = sb->s_options; 6502a32cebdSAl Viro rcu_assign_pointer(sb->s_options, options); 6512a32cebdSAl Viro if (old) { 6522a32cebdSAl Viro synchronize_rcu(); 6532a32cebdSAl Viro kfree(old); 6542a32cebdSAl Viro } 6552a32cebdSAl Viro } 6562a32cebdSAl Viro EXPORT_SYMBOL(replace_mount_options); 6572a32cebdSAl Viro 658a1a2c409SMiklos Szeredi #ifdef CONFIG_PROC_FS 6591da177e4SLinus Torvalds /* iterator */ 6601da177e4SLinus Torvalds static void *m_start(struct seq_file *m, loff_t *pos) 6611da177e4SLinus Torvalds { 662a1a2c409SMiklos Szeredi struct proc_mounts *p = m->private; 6631da177e4SLinus Torvalds 664390c6843SRam Pai down_read(&namespace_sem); 665a1a2c409SMiklos Szeredi return seq_list_start(&p->ns->list, *pos); 6661da177e4SLinus Torvalds } 6671da177e4SLinus Torvalds 6681da177e4SLinus Torvalds static void *m_next(struct seq_file *m, void *v, loff_t *pos) 6691da177e4SLinus Torvalds { 670a1a2c409SMiklos Szeredi struct proc_mounts *p = m->private; 671b0765fb8SPavel Emelianov 672a1a2c409SMiklos Szeredi return seq_list_next(v, &p->ns->list, pos); 6731da177e4SLinus Torvalds } 6741da177e4SLinus Torvalds 6751da177e4SLinus Torvalds static void m_stop(struct seq_file *m, void *v) 6761da177e4SLinus Torvalds { 677390c6843SRam Pai up_read(&namespace_sem); 6781da177e4SLinus Torvalds } 6791da177e4SLinus Torvalds 6802d4d4864SRam Pai struct proc_fs_info { 6811da177e4SLinus Torvalds int flag; 6822d4d4864SRam Pai const char *str; 6832d4d4864SRam Pai }; 6842d4d4864SRam Pai 6852069f457SEric Paris static int show_sb_opts(struct seq_file *m, struct super_block *sb) 6862d4d4864SRam Pai { 6872d4d4864SRam Pai static const struct proc_fs_info fs_info[] = { 6881da177e4SLinus Torvalds { MS_SYNCHRONOUS, ",sync" }, 6891da177e4SLinus Torvalds { MS_DIRSYNC, ",dirsync" }, 6901da177e4SLinus Torvalds { MS_MANDLOCK, ",mand" }, 6911da177e4SLinus Torvalds { 0, NULL } 6921da177e4SLinus Torvalds }; 6932d4d4864SRam Pai const struct proc_fs_info *fs_infop; 6942d4d4864SRam Pai 6952d4d4864SRam Pai for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { 6962d4d4864SRam Pai if (sb->s_flags & fs_infop->flag) 6972d4d4864SRam Pai seq_puts(m, fs_infop->str); 6982d4d4864SRam Pai } 6992069f457SEric Paris 7002069f457SEric Paris return security_sb_show_options(m, sb); 7012d4d4864SRam Pai } 7022d4d4864SRam Pai 7032d4d4864SRam Pai static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt) 7042d4d4864SRam Pai { 7052d4d4864SRam Pai static const struct proc_fs_info mnt_info[] = { 7061da177e4SLinus Torvalds { MNT_NOSUID, ",nosuid" }, 7071da177e4SLinus Torvalds { MNT_NODEV, ",nodev" }, 7081da177e4SLinus Torvalds { MNT_NOEXEC, ",noexec" }, 709fc33a7bbSChristoph Hellwig { MNT_NOATIME, ",noatime" }, 710fc33a7bbSChristoph Hellwig { MNT_NODIRATIME, ",nodiratime" }, 71147ae32d6SValerie Henson { MNT_RELATIME, ",relatime" }, 712d0adde57SMatthew Garrett { MNT_STRICTATIME, ",strictatime" }, 7131da177e4SLinus Torvalds { 0, NULL } 7141da177e4SLinus Torvalds }; 7152d4d4864SRam Pai const struct proc_fs_info *fs_infop; 7162d4d4864SRam Pai 7172d4d4864SRam Pai for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { 7182d4d4864SRam Pai if (mnt->mnt_flags & fs_infop->flag) 7192d4d4864SRam Pai seq_puts(m, fs_infop->str); 7202d4d4864SRam Pai } 7212d4d4864SRam Pai } 7222d4d4864SRam Pai 7232d4d4864SRam Pai static void show_type(struct seq_file *m, struct super_block *sb) 7242d4d4864SRam Pai { 7252d4d4864SRam Pai mangle(m, sb->s_type->name); 7262d4d4864SRam Pai if (sb->s_subtype && sb->s_subtype[0]) { 7272d4d4864SRam Pai seq_putc(m, '.'); 7282d4d4864SRam Pai mangle(m, sb->s_subtype); 7292d4d4864SRam Pai } 7302d4d4864SRam Pai } 7312d4d4864SRam Pai 7322d4d4864SRam Pai static int show_vfsmnt(struct seq_file *m, void *v) 7332d4d4864SRam Pai { 7342d4d4864SRam Pai struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); 7352d4d4864SRam Pai int err = 0; 736c32c2f63SJan Blunck struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; 7371da177e4SLinus Torvalds 7381da177e4SLinus Torvalds mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); 7391da177e4SLinus Torvalds seq_putc(m, ' '); 740c32c2f63SJan Blunck seq_path(m, &mnt_path, " \t\n\\"); 7411da177e4SLinus Torvalds seq_putc(m, ' '); 7422d4d4864SRam Pai show_type(m, mnt->mnt_sb); 7432e4b7fcdSDave Hansen seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw"); 7442069f457SEric Paris err = show_sb_opts(m, mnt->mnt_sb); 7452069f457SEric Paris if (err) 7462069f457SEric Paris goto out; 7472d4d4864SRam Pai show_mnt_opts(m, mnt); 7481da177e4SLinus Torvalds if (mnt->mnt_sb->s_op->show_options) 7491da177e4SLinus Torvalds err = mnt->mnt_sb->s_op->show_options(m, mnt); 7501da177e4SLinus Torvalds seq_puts(m, " 0 0\n"); 7512069f457SEric Paris out: 7521da177e4SLinus Torvalds return err; 7531da177e4SLinus Torvalds } 7541da177e4SLinus Torvalds 755a1a2c409SMiklos Szeredi const struct seq_operations mounts_op = { 7561da177e4SLinus Torvalds .start = m_start, 7571da177e4SLinus Torvalds .next = m_next, 7581da177e4SLinus Torvalds .stop = m_stop, 7591da177e4SLinus Torvalds .show = show_vfsmnt 7601da177e4SLinus Torvalds }; 7611da177e4SLinus Torvalds 7622d4d4864SRam Pai static int show_mountinfo(struct seq_file *m, void *v) 7632d4d4864SRam Pai { 7642d4d4864SRam Pai struct proc_mounts *p = m->private; 7652d4d4864SRam Pai struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); 7662d4d4864SRam Pai struct super_block *sb = mnt->mnt_sb; 7672d4d4864SRam Pai struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; 7682d4d4864SRam Pai struct path root = p->root; 7692d4d4864SRam Pai int err = 0; 7702d4d4864SRam Pai 7712d4d4864SRam Pai seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, mnt->mnt_parent->mnt_id, 7722d4d4864SRam Pai MAJOR(sb->s_dev), MINOR(sb->s_dev)); 7732d4d4864SRam Pai seq_dentry(m, mnt->mnt_root, " \t\n\\"); 7742d4d4864SRam Pai seq_putc(m, ' '); 7752d4d4864SRam Pai seq_path_root(m, &mnt_path, &root, " \t\n\\"); 7762d4d4864SRam Pai if (root.mnt != p->root.mnt || root.dentry != p->root.dentry) { 7772d4d4864SRam Pai /* 7782d4d4864SRam Pai * Mountpoint is outside root, discard that one. Ugly, 7792d4d4864SRam Pai * but less so than trying to do that in iterator in a 7802d4d4864SRam Pai * race-free way (due to renames). 7812d4d4864SRam Pai */ 7822d4d4864SRam Pai return SEQ_SKIP; 7832d4d4864SRam Pai } 7842d4d4864SRam Pai seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw"); 7852d4d4864SRam Pai show_mnt_opts(m, mnt); 7862d4d4864SRam Pai 7872d4d4864SRam Pai /* Tagged fields ("foo:X" or "bar") */ 7882d4d4864SRam Pai if (IS_MNT_SHARED(mnt)) 7892d4d4864SRam Pai seq_printf(m, " shared:%i", mnt->mnt_group_id); 79097e7e0f7SMiklos Szeredi if (IS_MNT_SLAVE(mnt)) { 79197e7e0f7SMiklos Szeredi int master = mnt->mnt_master->mnt_group_id; 79297e7e0f7SMiklos Szeredi int dom = get_dominating_id(mnt, &p->root); 79397e7e0f7SMiklos Szeredi seq_printf(m, " master:%i", master); 79497e7e0f7SMiklos Szeredi if (dom && dom != master) 79597e7e0f7SMiklos Szeredi seq_printf(m, " propagate_from:%i", dom); 79697e7e0f7SMiklos Szeredi } 7972d4d4864SRam Pai if (IS_MNT_UNBINDABLE(mnt)) 7982d4d4864SRam Pai seq_puts(m, " unbindable"); 7992d4d4864SRam Pai 8002d4d4864SRam Pai /* Filesystem specific data */ 8012d4d4864SRam Pai seq_puts(m, " - "); 8022d4d4864SRam Pai show_type(m, sb); 8032d4d4864SRam Pai seq_putc(m, ' '); 8042d4d4864SRam Pai mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); 8052d4d4864SRam Pai seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw"); 8062069f457SEric Paris err = show_sb_opts(m, sb); 8072069f457SEric Paris if (err) 8082069f457SEric Paris goto out; 8092d4d4864SRam Pai if (sb->s_op->show_options) 8102d4d4864SRam Pai err = sb->s_op->show_options(m, mnt); 8112d4d4864SRam Pai seq_putc(m, '\n'); 8122069f457SEric Paris out: 8132d4d4864SRam Pai return err; 8142d4d4864SRam Pai } 8152d4d4864SRam Pai 8162d4d4864SRam Pai const struct seq_operations mountinfo_op = { 8172d4d4864SRam Pai .start = m_start, 8182d4d4864SRam Pai .next = m_next, 8192d4d4864SRam Pai .stop = m_stop, 8202d4d4864SRam Pai .show = show_mountinfo, 8212d4d4864SRam Pai }; 8222d4d4864SRam Pai 823b4629fe2SChuck Lever static int show_vfsstat(struct seq_file *m, void *v) 824b4629fe2SChuck Lever { 825b0765fb8SPavel Emelianov struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); 826c32c2f63SJan Blunck struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; 827b4629fe2SChuck Lever int err = 0; 828b4629fe2SChuck Lever 829b4629fe2SChuck Lever /* device */ 830b4629fe2SChuck Lever if (mnt->mnt_devname) { 831b4629fe2SChuck Lever seq_puts(m, "device "); 832b4629fe2SChuck Lever mangle(m, mnt->mnt_devname); 833b4629fe2SChuck Lever } else 834b4629fe2SChuck Lever seq_puts(m, "no device"); 835b4629fe2SChuck Lever 836b4629fe2SChuck Lever /* mount point */ 837b4629fe2SChuck Lever seq_puts(m, " mounted on "); 838c32c2f63SJan Blunck seq_path(m, &mnt_path, " \t\n\\"); 839b4629fe2SChuck Lever seq_putc(m, ' '); 840b4629fe2SChuck Lever 841b4629fe2SChuck Lever /* file system type */ 842b4629fe2SChuck Lever seq_puts(m, "with fstype "); 8432d4d4864SRam Pai show_type(m, mnt->mnt_sb); 844b4629fe2SChuck Lever 845b4629fe2SChuck Lever /* optional statistics */ 846b4629fe2SChuck Lever if (mnt->mnt_sb->s_op->show_stats) { 847b4629fe2SChuck Lever seq_putc(m, ' '); 848b4629fe2SChuck Lever err = mnt->mnt_sb->s_op->show_stats(m, mnt); 849b4629fe2SChuck Lever } 850b4629fe2SChuck Lever 851b4629fe2SChuck Lever seq_putc(m, '\n'); 852b4629fe2SChuck Lever return err; 853b4629fe2SChuck Lever } 854b4629fe2SChuck Lever 855a1a2c409SMiklos Szeredi const struct seq_operations mountstats_op = { 856b4629fe2SChuck Lever .start = m_start, 857b4629fe2SChuck Lever .next = m_next, 858b4629fe2SChuck Lever .stop = m_stop, 859b4629fe2SChuck Lever .show = show_vfsstat, 860b4629fe2SChuck Lever }; 861a1a2c409SMiklos Szeredi #endif /* CONFIG_PROC_FS */ 862b4629fe2SChuck Lever 8631da177e4SLinus Torvalds /** 8641da177e4SLinus Torvalds * may_umount_tree - check if a mount tree is busy 8651da177e4SLinus Torvalds * @mnt: root of mount tree 8661da177e4SLinus Torvalds * 8671da177e4SLinus Torvalds * This is called to check if a tree of mounts has any 8681da177e4SLinus Torvalds * open files, pwds, chroots or sub mounts that are 8691da177e4SLinus Torvalds * busy. 8701da177e4SLinus Torvalds */ 8711da177e4SLinus Torvalds int may_umount_tree(struct vfsmount *mnt) 8721da177e4SLinus Torvalds { 87336341f64SRam Pai int actual_refs = 0; 87436341f64SRam Pai int minimum_refs = 0; 87536341f64SRam Pai struct vfsmount *p; 8761da177e4SLinus Torvalds 8771da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 87836341f64SRam Pai for (p = mnt; p; p = next_mnt(p, mnt)) { 8791da177e4SLinus Torvalds actual_refs += atomic_read(&p->mnt_count); 8801da177e4SLinus Torvalds minimum_refs += 2; 8811da177e4SLinus Torvalds } 8821da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 8831da177e4SLinus Torvalds 8841da177e4SLinus Torvalds if (actual_refs > minimum_refs) 8851da177e4SLinus Torvalds return 0; 886e3474a8eSIan Kent 887e3474a8eSIan Kent return 1; 8881da177e4SLinus Torvalds } 8891da177e4SLinus Torvalds 8901da177e4SLinus Torvalds EXPORT_SYMBOL(may_umount_tree); 8911da177e4SLinus Torvalds 8921da177e4SLinus Torvalds /** 8931da177e4SLinus Torvalds * may_umount - check if a mount point is busy 8941da177e4SLinus Torvalds * @mnt: root of mount 8951da177e4SLinus Torvalds * 8961da177e4SLinus Torvalds * This is called to check if a mount point has any 8971da177e4SLinus Torvalds * open files, pwds, chroots or sub mounts. If the 8981da177e4SLinus Torvalds * mount has sub mounts this will return busy 8991da177e4SLinus Torvalds * regardless of whether the sub mounts are busy. 9001da177e4SLinus Torvalds * 9011da177e4SLinus Torvalds * Doesn't take quota and stuff into account. IOW, in some cases it will 9021da177e4SLinus Torvalds * give false negatives. The main reason why it's here is that we need 9031da177e4SLinus Torvalds * a non-destructive way to look for easily umountable filesystems. 9041da177e4SLinus Torvalds */ 9051da177e4SLinus Torvalds int may_umount(struct vfsmount *mnt) 9061da177e4SLinus Torvalds { 907e3474a8eSIan Kent int ret = 1; 908a05964f3SRam Pai spin_lock(&vfsmount_lock); 909a05964f3SRam Pai if (propagate_mount_busy(mnt, 2)) 910e3474a8eSIan Kent ret = 0; 911a05964f3SRam Pai spin_unlock(&vfsmount_lock); 912a05964f3SRam Pai return ret; 9131da177e4SLinus Torvalds } 9141da177e4SLinus Torvalds 9151da177e4SLinus Torvalds EXPORT_SYMBOL(may_umount); 9161da177e4SLinus Torvalds 917b90fa9aeSRam Pai void release_mounts(struct list_head *head) 9181da177e4SLinus Torvalds { 91970fbcdf4SRam Pai struct vfsmount *mnt; 92070fbcdf4SRam Pai while (!list_empty(head)) { 921b5e61818SPavel Emelianov mnt = list_first_entry(head, struct vfsmount, mnt_hash); 92270fbcdf4SRam Pai list_del_init(&mnt->mnt_hash); 92370fbcdf4SRam Pai if (mnt->mnt_parent != mnt) { 92470fbcdf4SRam Pai struct dentry *dentry; 92570fbcdf4SRam Pai struct vfsmount *m; 92670fbcdf4SRam Pai spin_lock(&vfsmount_lock); 92770fbcdf4SRam Pai dentry = mnt->mnt_mountpoint; 92870fbcdf4SRam Pai m = mnt->mnt_parent; 92970fbcdf4SRam Pai mnt->mnt_mountpoint = mnt->mnt_root; 93070fbcdf4SRam Pai mnt->mnt_parent = mnt; 9317c4b93d8SAl Viro m->mnt_ghosts--; 9321da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 93370fbcdf4SRam Pai dput(dentry); 93470fbcdf4SRam Pai mntput(m); 9351da177e4SLinus Torvalds } 9361da177e4SLinus Torvalds mntput(mnt); 93770fbcdf4SRam Pai } 93870fbcdf4SRam Pai } 93970fbcdf4SRam Pai 940a05964f3SRam Pai void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) 94170fbcdf4SRam Pai { 94270fbcdf4SRam Pai struct vfsmount *p; 94370fbcdf4SRam Pai 9441bfba4e8SAkinobu Mita for (p = mnt; p; p = next_mnt(p, mnt)) 9451bfba4e8SAkinobu Mita list_move(&p->mnt_hash, kill); 94670fbcdf4SRam Pai 947a05964f3SRam Pai if (propagate) 948a05964f3SRam Pai propagate_umount(kill); 949a05964f3SRam Pai 95070fbcdf4SRam Pai list_for_each_entry(p, kill, mnt_hash) { 95170fbcdf4SRam Pai list_del_init(&p->mnt_expire); 95270fbcdf4SRam Pai list_del_init(&p->mnt_list); 9536b3286edSKirill Korotaev __touch_mnt_namespace(p->mnt_ns); 9546b3286edSKirill Korotaev p->mnt_ns = NULL; 95570fbcdf4SRam Pai list_del_init(&p->mnt_child); 9567c4b93d8SAl Viro if (p->mnt_parent != p) { 9577c4b93d8SAl Viro p->mnt_parent->mnt_ghosts++; 958f30ac319SAl Viro p->mnt_mountpoint->d_mounted--; 9597c4b93d8SAl Viro } 960a05964f3SRam Pai change_mnt_propagation(p, MS_PRIVATE); 9611da177e4SLinus Torvalds } 9621da177e4SLinus Torvalds } 9631da177e4SLinus Torvalds 964c35038beSAl Viro static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts); 965c35038beSAl Viro 9661da177e4SLinus Torvalds static int do_umount(struct vfsmount *mnt, int flags) 9671da177e4SLinus Torvalds { 9681da177e4SLinus Torvalds struct super_block *sb = mnt->mnt_sb; 9691da177e4SLinus Torvalds int retval; 97070fbcdf4SRam Pai LIST_HEAD(umount_list); 9711da177e4SLinus Torvalds 9721da177e4SLinus Torvalds retval = security_sb_umount(mnt, flags); 9731da177e4SLinus Torvalds if (retval) 9741da177e4SLinus Torvalds return retval; 9751da177e4SLinus Torvalds 9761da177e4SLinus Torvalds /* 9771da177e4SLinus Torvalds * Allow userspace to request a mountpoint be expired rather than 9781da177e4SLinus Torvalds * unmounting unconditionally. Unmount only happens if: 9791da177e4SLinus Torvalds * (1) the mark is already set (the mark is cleared by mntput()) 9801da177e4SLinus Torvalds * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] 9811da177e4SLinus Torvalds */ 9821da177e4SLinus Torvalds if (flags & MNT_EXPIRE) { 9836ac08c39SJan Blunck if (mnt == current->fs->root.mnt || 9841da177e4SLinus Torvalds flags & (MNT_FORCE | MNT_DETACH)) 9851da177e4SLinus Torvalds return -EINVAL; 9861da177e4SLinus Torvalds 9871da177e4SLinus Torvalds if (atomic_read(&mnt->mnt_count) != 2) 9881da177e4SLinus Torvalds return -EBUSY; 9891da177e4SLinus Torvalds 9901da177e4SLinus Torvalds if (!xchg(&mnt->mnt_expiry_mark, 1)) 9911da177e4SLinus Torvalds return -EAGAIN; 9921da177e4SLinus Torvalds } 9931da177e4SLinus Torvalds 9941da177e4SLinus Torvalds /* 9951da177e4SLinus Torvalds * If we may have to abort operations to get out of this 9961da177e4SLinus Torvalds * mount, and they will themselves hold resources we must 9971da177e4SLinus Torvalds * allow the fs to do things. In the Unix tradition of 9981da177e4SLinus Torvalds * 'Gee thats tricky lets do it in userspace' the umount_begin 9991da177e4SLinus Torvalds * might fail to complete on the first run through as other tasks 10001da177e4SLinus Torvalds * must return, and the like. Thats for the mount program to worry 10011da177e4SLinus Torvalds * about for the moment. 10021da177e4SLinus Torvalds */ 10031da177e4SLinus Torvalds 100442faad99SAl Viro if (flags & MNT_FORCE && sb->s_op->umount_begin) { 100542faad99SAl Viro sb->s_op->umount_begin(sb); 100642faad99SAl Viro } 10071da177e4SLinus Torvalds 10081da177e4SLinus Torvalds /* 10091da177e4SLinus Torvalds * No sense to grab the lock for this test, but test itself looks 10101da177e4SLinus Torvalds * somewhat bogus. Suggestions for better replacement? 10111da177e4SLinus Torvalds * Ho-hum... In principle, we might treat that as umount + switch 10121da177e4SLinus Torvalds * to rootfs. GC would eventually take care of the old vfsmount. 10131da177e4SLinus Torvalds * Actually it makes sense, especially if rootfs would contain a 10141da177e4SLinus Torvalds * /reboot - static binary that would close all descriptors and 10151da177e4SLinus Torvalds * call reboot(9). Then init(8) could umount root and exec /reboot. 10161da177e4SLinus Torvalds */ 10176ac08c39SJan Blunck if (mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) { 10181da177e4SLinus Torvalds /* 10191da177e4SLinus Torvalds * Special case for "unmounting" root ... 10201da177e4SLinus Torvalds * we just try to remount it readonly. 10211da177e4SLinus Torvalds */ 10221da177e4SLinus Torvalds down_write(&sb->s_umount); 10231da177e4SLinus Torvalds if (!(sb->s_flags & MS_RDONLY)) { 10241da177e4SLinus Torvalds lock_kernel(); 10251da177e4SLinus Torvalds retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); 10261da177e4SLinus Torvalds unlock_kernel(); 10271da177e4SLinus Torvalds } 10281da177e4SLinus Torvalds up_write(&sb->s_umount); 10291da177e4SLinus Torvalds return retval; 10301da177e4SLinus Torvalds } 10311da177e4SLinus Torvalds 1032390c6843SRam Pai down_write(&namespace_sem); 10331da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 10345addc5ddSAl Viro event++; 10351da177e4SLinus Torvalds 1036c35038beSAl Viro if (!(flags & MNT_DETACH)) 1037c35038beSAl Viro shrink_submounts(mnt, &umount_list); 1038c35038beSAl Viro 10391da177e4SLinus Torvalds retval = -EBUSY; 1040a05964f3SRam Pai if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) { 10411da177e4SLinus Torvalds if (!list_empty(&mnt->mnt_list)) 1042a05964f3SRam Pai umount_tree(mnt, 1, &umount_list); 10431da177e4SLinus Torvalds retval = 0; 10441da177e4SLinus Torvalds } 10451da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 10461da177e4SLinus Torvalds if (retval) 10471da177e4SLinus Torvalds security_sb_umount_busy(mnt); 1048390c6843SRam Pai up_write(&namespace_sem); 104970fbcdf4SRam Pai release_mounts(&umount_list); 10501da177e4SLinus Torvalds return retval; 10511da177e4SLinus Torvalds } 10521da177e4SLinus Torvalds 10531da177e4SLinus Torvalds /* 10541da177e4SLinus Torvalds * Now umount can handle mount points as well as block devices. 10551da177e4SLinus Torvalds * This is important for filesystems which use unnamed block devices. 10561da177e4SLinus Torvalds * 10571da177e4SLinus Torvalds * We now support a flag for forced unmount like the other 'big iron' 10581da177e4SLinus Torvalds * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD 10591da177e4SLinus Torvalds */ 10601da177e4SLinus Torvalds 1061bdc480e3SHeiko Carstens SYSCALL_DEFINE2(umount, char __user *, name, int, flags) 10621da177e4SLinus Torvalds { 10632d8f3038SAl Viro struct path path; 10641da177e4SLinus Torvalds int retval; 10651da177e4SLinus Torvalds 10662d8f3038SAl Viro retval = user_path(name, &path); 10671da177e4SLinus Torvalds if (retval) 10681da177e4SLinus Torvalds goto out; 10691da177e4SLinus Torvalds retval = -EINVAL; 10702d8f3038SAl Viro if (path.dentry != path.mnt->mnt_root) 10711da177e4SLinus Torvalds goto dput_and_out; 10722d8f3038SAl Viro if (!check_mnt(path.mnt)) 10731da177e4SLinus Torvalds goto dput_and_out; 10741da177e4SLinus Torvalds 10751da177e4SLinus Torvalds retval = -EPERM; 10761da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 10771da177e4SLinus Torvalds goto dput_and_out; 10781da177e4SLinus Torvalds 10792d8f3038SAl Viro retval = do_umount(path.mnt, flags); 10801da177e4SLinus Torvalds dput_and_out: 1081429731b1SJan Blunck /* we mustn't call path_put() as that would clear mnt_expiry_mark */ 10822d8f3038SAl Viro dput(path.dentry); 10832d8f3038SAl Viro mntput_no_expire(path.mnt); 10841da177e4SLinus Torvalds out: 10851da177e4SLinus Torvalds return retval; 10861da177e4SLinus Torvalds } 10871da177e4SLinus Torvalds 10881da177e4SLinus Torvalds #ifdef __ARCH_WANT_SYS_OLDUMOUNT 10891da177e4SLinus Torvalds 10901da177e4SLinus Torvalds /* 10911da177e4SLinus Torvalds * The 2.0 compatible umount. No flags. 10921da177e4SLinus Torvalds */ 1093bdc480e3SHeiko Carstens SYSCALL_DEFINE1(oldumount, char __user *, name) 10941da177e4SLinus Torvalds { 10951da177e4SLinus Torvalds return sys_umount(name, 0); 10961da177e4SLinus Torvalds } 10971da177e4SLinus Torvalds 10981da177e4SLinus Torvalds #endif 10991da177e4SLinus Torvalds 11002d92ab3cSAl Viro static int mount_is_safe(struct path *path) 11011da177e4SLinus Torvalds { 11021da177e4SLinus Torvalds if (capable(CAP_SYS_ADMIN)) 11031da177e4SLinus Torvalds return 0; 11041da177e4SLinus Torvalds return -EPERM; 11051da177e4SLinus Torvalds #ifdef notyet 11062d92ab3cSAl Viro if (S_ISLNK(path->dentry->d_inode->i_mode)) 11071da177e4SLinus Torvalds return -EPERM; 11082d92ab3cSAl Viro if (path->dentry->d_inode->i_mode & S_ISVTX) { 1109da9592edSDavid Howells if (current_uid() != path->dentry->d_inode->i_uid) 11101da177e4SLinus Torvalds return -EPERM; 11111da177e4SLinus Torvalds } 11122d92ab3cSAl Viro if (inode_permission(path->dentry->d_inode, MAY_WRITE)) 11131da177e4SLinus Torvalds return -EPERM; 11141da177e4SLinus Torvalds return 0; 11151da177e4SLinus Torvalds #endif 11161da177e4SLinus Torvalds } 11171da177e4SLinus Torvalds 1118b90fa9aeSRam Pai struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, 111936341f64SRam Pai int flag) 11201da177e4SLinus Torvalds { 11211da177e4SLinus Torvalds struct vfsmount *res, *p, *q, *r, *s; 11221a390689SAl Viro struct path path; 11231da177e4SLinus Torvalds 11249676f0c6SRam Pai if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt)) 11259676f0c6SRam Pai return NULL; 11269676f0c6SRam Pai 112736341f64SRam Pai res = q = clone_mnt(mnt, dentry, flag); 11281da177e4SLinus Torvalds if (!q) 11291da177e4SLinus Torvalds goto Enomem; 11301da177e4SLinus Torvalds q->mnt_mountpoint = mnt->mnt_mountpoint; 11311da177e4SLinus Torvalds 11321da177e4SLinus Torvalds p = mnt; 1133fdadd65fSDomen Puncer list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { 11347ec02ef1SJan Blunck if (!is_subdir(r->mnt_mountpoint, dentry)) 11351da177e4SLinus Torvalds continue; 11361da177e4SLinus Torvalds 11371da177e4SLinus Torvalds for (s = r; s; s = next_mnt(s, r)) { 11389676f0c6SRam Pai if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) { 11399676f0c6SRam Pai s = skip_mnt_tree(s); 11409676f0c6SRam Pai continue; 11419676f0c6SRam Pai } 11421da177e4SLinus Torvalds while (p != s->mnt_parent) { 11431da177e4SLinus Torvalds p = p->mnt_parent; 11441da177e4SLinus Torvalds q = q->mnt_parent; 11451da177e4SLinus Torvalds } 11461da177e4SLinus Torvalds p = s; 11471a390689SAl Viro path.mnt = q; 11481a390689SAl Viro path.dentry = p->mnt_mountpoint; 114936341f64SRam Pai q = clone_mnt(p, p->mnt_root, flag); 11501da177e4SLinus Torvalds if (!q) 11511da177e4SLinus Torvalds goto Enomem; 11521da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 11531da177e4SLinus Torvalds list_add_tail(&q->mnt_list, &res->mnt_list); 11541a390689SAl Viro attach_mnt(q, &path); 11551da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 11561da177e4SLinus Torvalds } 11571da177e4SLinus Torvalds } 11581da177e4SLinus Torvalds return res; 11591da177e4SLinus Torvalds Enomem: 11601da177e4SLinus Torvalds if (res) { 116170fbcdf4SRam Pai LIST_HEAD(umount_list); 11621da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 1163a05964f3SRam Pai umount_tree(res, 0, &umount_list); 11641da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 116570fbcdf4SRam Pai release_mounts(&umount_list); 11661da177e4SLinus Torvalds } 11671da177e4SLinus Torvalds return NULL; 11681da177e4SLinus Torvalds } 11691da177e4SLinus Torvalds 1170589ff870SAl Viro struct vfsmount *collect_mounts(struct path *path) 11718aec0809SAl Viro { 11728aec0809SAl Viro struct vfsmount *tree; 11731a60a280SAl Viro down_write(&namespace_sem); 1174589ff870SAl Viro tree = copy_tree(path->mnt, path->dentry, CL_COPY_ALL | CL_PRIVATE); 11751a60a280SAl Viro up_write(&namespace_sem); 11768aec0809SAl Viro return tree; 11778aec0809SAl Viro } 11788aec0809SAl Viro 11798aec0809SAl Viro void drop_collected_mounts(struct vfsmount *mnt) 11808aec0809SAl Viro { 11818aec0809SAl Viro LIST_HEAD(umount_list); 11821a60a280SAl Viro down_write(&namespace_sem); 11838aec0809SAl Viro spin_lock(&vfsmount_lock); 11848aec0809SAl Viro umount_tree(mnt, 0, &umount_list); 11858aec0809SAl Viro spin_unlock(&vfsmount_lock); 11861a60a280SAl Viro up_write(&namespace_sem); 11878aec0809SAl Viro release_mounts(&umount_list); 11888aec0809SAl Viro } 11898aec0809SAl Viro 1190719f5d7fSMiklos Szeredi static void cleanup_group_ids(struct vfsmount *mnt, struct vfsmount *end) 1191719f5d7fSMiklos Szeredi { 1192719f5d7fSMiklos Szeredi struct vfsmount *p; 1193719f5d7fSMiklos Szeredi 1194719f5d7fSMiklos Szeredi for (p = mnt; p != end; p = next_mnt(p, mnt)) { 1195719f5d7fSMiklos Szeredi if (p->mnt_group_id && !IS_MNT_SHARED(p)) 1196719f5d7fSMiklos Szeredi mnt_release_group_id(p); 1197719f5d7fSMiklos Szeredi } 1198719f5d7fSMiklos Szeredi } 1199719f5d7fSMiklos Szeredi 1200719f5d7fSMiklos Szeredi static int invent_group_ids(struct vfsmount *mnt, bool recurse) 1201719f5d7fSMiklos Szeredi { 1202719f5d7fSMiklos Szeredi struct vfsmount *p; 1203719f5d7fSMiklos Szeredi 1204719f5d7fSMiklos Szeredi for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) { 1205719f5d7fSMiklos Szeredi if (!p->mnt_group_id && !IS_MNT_SHARED(p)) { 1206719f5d7fSMiklos Szeredi int err = mnt_alloc_group_id(p); 1207719f5d7fSMiklos Szeredi if (err) { 1208719f5d7fSMiklos Szeredi cleanup_group_ids(mnt, p); 1209719f5d7fSMiklos Szeredi return err; 1210719f5d7fSMiklos Szeredi } 1211719f5d7fSMiklos Szeredi } 1212719f5d7fSMiklos Szeredi } 1213719f5d7fSMiklos Szeredi 1214719f5d7fSMiklos Szeredi return 0; 1215719f5d7fSMiklos Szeredi } 1216719f5d7fSMiklos Szeredi 1217b90fa9aeSRam Pai /* 1218b90fa9aeSRam Pai * @source_mnt : mount tree to be attached 1219b90fa9aeSRam Pai * @nd : place the mount tree @source_mnt is attached 122021444403SRam Pai * @parent_nd : if non-null, detach the source_mnt from its parent and 122121444403SRam Pai * store the parent mount and mountpoint dentry. 122221444403SRam Pai * (done when source_mnt is moved) 1223b90fa9aeSRam Pai * 1224b90fa9aeSRam Pai * NOTE: in the table below explains the semantics when a source mount 1225b90fa9aeSRam Pai * of a given type is attached to a destination mount of a given type. 12269676f0c6SRam Pai * --------------------------------------------------------------------------- 1227b90fa9aeSRam Pai * | BIND MOUNT OPERATION | 12289676f0c6SRam Pai * |************************************************************************** 12299676f0c6SRam Pai * | source-->| shared | private | slave | unbindable | 12309676f0c6SRam Pai * | dest | | | | | 12319676f0c6SRam Pai * | | | | | | | 12329676f0c6SRam Pai * | v | | | | | 12339676f0c6SRam Pai * |************************************************************************** 12349676f0c6SRam Pai * | shared | shared (++) | shared (+) | shared(+++)| invalid | 12355afe0022SRam Pai * | | | | | | 12369676f0c6SRam Pai * |non-shared| shared (+) | private | slave (*) | invalid | 12379676f0c6SRam Pai * *************************************************************************** 1238b90fa9aeSRam Pai * A bind operation clones the source mount and mounts the clone on the 1239b90fa9aeSRam Pai * destination mount. 1240b90fa9aeSRam Pai * 1241b90fa9aeSRam Pai * (++) the cloned mount is propagated to all the mounts in the propagation 1242b90fa9aeSRam Pai * tree of the destination mount and the cloned mount is added to 1243b90fa9aeSRam Pai * the peer group of the source mount. 1244b90fa9aeSRam Pai * (+) the cloned mount is created under the destination mount and is marked 1245b90fa9aeSRam Pai * as shared. The cloned mount is added to the peer group of the source 1246b90fa9aeSRam Pai * mount. 12475afe0022SRam Pai * (+++) the mount is propagated to all the mounts in the propagation tree 12485afe0022SRam Pai * of the destination mount and the cloned mount is made slave 12495afe0022SRam Pai * of the same master as that of the source mount. The cloned mount 12505afe0022SRam Pai * is marked as 'shared and slave'. 12515afe0022SRam Pai * (*) the cloned mount is made a slave of the same master as that of the 12525afe0022SRam Pai * source mount. 12535afe0022SRam Pai * 12549676f0c6SRam Pai * --------------------------------------------------------------------------- 125521444403SRam Pai * | MOVE MOUNT OPERATION | 12569676f0c6SRam Pai * |************************************************************************** 12579676f0c6SRam Pai * | source-->| shared | private | slave | unbindable | 12589676f0c6SRam Pai * | dest | | | | | 12599676f0c6SRam Pai * | | | | | | | 12609676f0c6SRam Pai * | v | | | | | 12619676f0c6SRam Pai * |************************************************************************** 12629676f0c6SRam Pai * | shared | shared (+) | shared (+) | shared(+++) | invalid | 12635afe0022SRam Pai * | | | | | | 12649676f0c6SRam Pai * |non-shared| shared (+*) | private | slave (*) | unbindable | 12659676f0c6SRam Pai * *************************************************************************** 12665afe0022SRam Pai * 12675afe0022SRam Pai * (+) the mount is moved to the destination. And is then propagated to 12685afe0022SRam Pai * all the mounts in the propagation tree of the destination mount. 126921444403SRam Pai * (+*) the mount is moved to the destination. 12705afe0022SRam Pai * (+++) the mount is moved to the destination and is then propagated to 12715afe0022SRam Pai * all the mounts belonging to the destination mount's propagation tree. 12725afe0022SRam Pai * the mount is marked as 'shared and slave'. 12735afe0022SRam Pai * (*) the mount continues to be a slave at the new location. 1274b90fa9aeSRam Pai * 1275b90fa9aeSRam Pai * if the source mount is a tree, the operations explained above is 1276b90fa9aeSRam Pai * applied to each mount in the tree. 1277b90fa9aeSRam Pai * Must be called without spinlocks held, since this function can sleep 1278b90fa9aeSRam Pai * in allocations. 1279b90fa9aeSRam Pai */ 1280b90fa9aeSRam Pai static int attach_recursive_mnt(struct vfsmount *source_mnt, 12811a390689SAl Viro struct path *path, struct path *parent_path) 1282b90fa9aeSRam Pai { 1283b90fa9aeSRam Pai LIST_HEAD(tree_list); 12841a390689SAl Viro struct vfsmount *dest_mnt = path->mnt; 12851a390689SAl Viro struct dentry *dest_dentry = path->dentry; 1286b90fa9aeSRam Pai struct vfsmount *child, *p; 1287719f5d7fSMiklos Szeredi int err; 1288b90fa9aeSRam Pai 1289719f5d7fSMiklos Szeredi if (IS_MNT_SHARED(dest_mnt)) { 1290719f5d7fSMiklos Szeredi err = invent_group_ids(source_mnt, true); 1291719f5d7fSMiklos Szeredi if (err) 1292719f5d7fSMiklos Szeredi goto out; 1293719f5d7fSMiklos Szeredi } 1294719f5d7fSMiklos Szeredi err = propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list); 1295719f5d7fSMiklos Szeredi if (err) 1296719f5d7fSMiklos Szeredi goto out_cleanup_ids; 1297b90fa9aeSRam Pai 1298b90fa9aeSRam Pai if (IS_MNT_SHARED(dest_mnt)) { 1299b90fa9aeSRam Pai for (p = source_mnt; p; p = next_mnt(p, source_mnt)) 1300b90fa9aeSRam Pai set_mnt_shared(p); 1301b90fa9aeSRam Pai } 1302b90fa9aeSRam Pai 1303b90fa9aeSRam Pai spin_lock(&vfsmount_lock); 13041a390689SAl Viro if (parent_path) { 13051a390689SAl Viro detach_mnt(source_mnt, parent_path); 13061a390689SAl Viro attach_mnt(source_mnt, path); 1307e5d67f07SAl Viro touch_mnt_namespace(parent_path->mnt->mnt_ns); 130821444403SRam Pai } else { 1309b90fa9aeSRam Pai mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt); 1310b90fa9aeSRam Pai commit_tree(source_mnt); 131121444403SRam Pai } 1312b90fa9aeSRam Pai 1313b90fa9aeSRam Pai list_for_each_entry_safe(child, p, &tree_list, mnt_hash) { 1314b90fa9aeSRam Pai list_del_init(&child->mnt_hash); 1315b90fa9aeSRam Pai commit_tree(child); 1316b90fa9aeSRam Pai } 1317b90fa9aeSRam Pai spin_unlock(&vfsmount_lock); 1318b90fa9aeSRam Pai return 0; 1319719f5d7fSMiklos Szeredi 1320719f5d7fSMiklos Szeredi out_cleanup_ids: 1321719f5d7fSMiklos Szeredi if (IS_MNT_SHARED(dest_mnt)) 1322719f5d7fSMiklos Szeredi cleanup_group_ids(source_mnt, NULL); 1323719f5d7fSMiklos Szeredi out: 1324719f5d7fSMiklos Szeredi return err; 1325b90fa9aeSRam Pai } 1326b90fa9aeSRam Pai 13278c3ee42eSAl Viro static int graft_tree(struct vfsmount *mnt, struct path *path) 13281da177e4SLinus Torvalds { 13291da177e4SLinus Torvalds int err; 13301da177e4SLinus Torvalds if (mnt->mnt_sb->s_flags & MS_NOUSER) 13311da177e4SLinus Torvalds return -EINVAL; 13321da177e4SLinus Torvalds 13338c3ee42eSAl Viro if (S_ISDIR(path->dentry->d_inode->i_mode) != 13341da177e4SLinus Torvalds S_ISDIR(mnt->mnt_root->d_inode->i_mode)) 13351da177e4SLinus Torvalds return -ENOTDIR; 13361da177e4SLinus Torvalds 13371da177e4SLinus Torvalds err = -ENOENT; 13388c3ee42eSAl Viro mutex_lock(&path->dentry->d_inode->i_mutex); 13398c3ee42eSAl Viro if (IS_DEADDIR(path->dentry->d_inode)) 13401da177e4SLinus Torvalds goto out_unlock; 13411da177e4SLinus Torvalds 13428c3ee42eSAl Viro err = security_sb_check_sb(mnt, path); 13431da177e4SLinus Torvalds if (err) 13441da177e4SLinus Torvalds goto out_unlock; 13451da177e4SLinus Torvalds 13461da177e4SLinus Torvalds err = -ENOENT; 13478c3ee42eSAl Viro if (IS_ROOT(path->dentry) || !d_unhashed(path->dentry)) 13488c3ee42eSAl Viro err = attach_recursive_mnt(mnt, path, NULL); 13491da177e4SLinus Torvalds out_unlock: 13508c3ee42eSAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 13511da177e4SLinus Torvalds if (!err) 13528c3ee42eSAl Viro security_sb_post_addmount(mnt, path); 13531da177e4SLinus Torvalds return err; 13541da177e4SLinus Torvalds } 13551da177e4SLinus Torvalds 13561da177e4SLinus Torvalds /* 135707b20889SRam Pai * recursively change the type of the mountpoint. 135807b20889SRam Pai */ 13590a0d8a46SAl Viro static int do_change_type(struct path *path, int flag) 136007b20889SRam Pai { 13612d92ab3cSAl Viro struct vfsmount *m, *mnt = path->mnt; 136207b20889SRam Pai int recurse = flag & MS_REC; 136307b20889SRam Pai int type = flag & ~MS_REC; 1364719f5d7fSMiklos Szeredi int err = 0; 136507b20889SRam Pai 1366ee6f9582SMiklos Szeredi if (!capable(CAP_SYS_ADMIN)) 1367ee6f9582SMiklos Szeredi return -EPERM; 1368ee6f9582SMiklos Szeredi 13692d92ab3cSAl Viro if (path->dentry != path->mnt->mnt_root) 137007b20889SRam Pai return -EINVAL; 137107b20889SRam Pai 137207b20889SRam Pai down_write(&namespace_sem); 1373719f5d7fSMiklos Szeredi if (type == MS_SHARED) { 1374719f5d7fSMiklos Szeredi err = invent_group_ids(mnt, recurse); 1375719f5d7fSMiklos Szeredi if (err) 1376719f5d7fSMiklos Szeredi goto out_unlock; 1377719f5d7fSMiklos Szeredi } 1378719f5d7fSMiklos Szeredi 137907b20889SRam Pai spin_lock(&vfsmount_lock); 138007b20889SRam Pai for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) 138107b20889SRam Pai change_mnt_propagation(m, type); 138207b20889SRam Pai spin_unlock(&vfsmount_lock); 1383719f5d7fSMiklos Szeredi 1384719f5d7fSMiklos Szeredi out_unlock: 138507b20889SRam Pai up_write(&namespace_sem); 1386719f5d7fSMiklos Szeredi return err; 138707b20889SRam Pai } 138807b20889SRam Pai 138907b20889SRam Pai /* 13901da177e4SLinus Torvalds * do loopback mount. 13911da177e4SLinus Torvalds */ 13920a0d8a46SAl Viro static int do_loopback(struct path *path, char *old_name, 13932dafe1c4SEric Sandeen int recurse) 13941da177e4SLinus Torvalds { 13952d92ab3cSAl Viro struct path old_path; 13961da177e4SLinus Torvalds struct vfsmount *mnt = NULL; 13972d92ab3cSAl Viro int err = mount_is_safe(path); 13981da177e4SLinus Torvalds if (err) 13991da177e4SLinus Torvalds return err; 14001da177e4SLinus Torvalds if (!old_name || !*old_name) 14011da177e4SLinus Torvalds return -EINVAL; 14022d92ab3cSAl Viro err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); 14031da177e4SLinus Torvalds if (err) 14041da177e4SLinus Torvalds return err; 14051da177e4SLinus Torvalds 1406390c6843SRam Pai down_write(&namespace_sem); 14071da177e4SLinus Torvalds err = -EINVAL; 14082d92ab3cSAl Viro if (IS_MNT_UNBINDABLE(old_path.mnt)) 14099676f0c6SRam Pai goto out; 14109676f0c6SRam Pai 14112d92ab3cSAl Viro if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt)) 1412ccd48bc7SAl Viro goto out; 1413ccd48bc7SAl Viro 14141da177e4SLinus Torvalds err = -ENOMEM; 14151da177e4SLinus Torvalds if (recurse) 14162d92ab3cSAl Viro mnt = copy_tree(old_path.mnt, old_path.dentry, 0); 14171da177e4SLinus Torvalds else 14182d92ab3cSAl Viro mnt = clone_mnt(old_path.mnt, old_path.dentry, 0); 14191da177e4SLinus Torvalds 1420ccd48bc7SAl Viro if (!mnt) 1421ccd48bc7SAl Viro goto out; 1422ccd48bc7SAl Viro 14232d92ab3cSAl Viro err = graft_tree(mnt, path); 14241da177e4SLinus Torvalds if (err) { 142570fbcdf4SRam Pai LIST_HEAD(umount_list); 14261da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 1427a05964f3SRam Pai umount_tree(mnt, 0, &umount_list); 14281da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 142970fbcdf4SRam Pai release_mounts(&umount_list); 14305b83d2c5SRam Pai } 14311da177e4SLinus Torvalds 1432ccd48bc7SAl Viro out: 1433390c6843SRam Pai up_write(&namespace_sem); 14342d92ab3cSAl Viro path_put(&old_path); 14351da177e4SLinus Torvalds return err; 14361da177e4SLinus Torvalds } 14371da177e4SLinus Torvalds 14382e4b7fcdSDave Hansen static int change_mount_flags(struct vfsmount *mnt, int ms_flags) 14392e4b7fcdSDave Hansen { 14402e4b7fcdSDave Hansen int error = 0; 14412e4b7fcdSDave Hansen int readonly_request = 0; 14422e4b7fcdSDave Hansen 14432e4b7fcdSDave Hansen if (ms_flags & MS_RDONLY) 14442e4b7fcdSDave Hansen readonly_request = 1; 14452e4b7fcdSDave Hansen if (readonly_request == __mnt_is_readonly(mnt)) 14462e4b7fcdSDave Hansen return 0; 14472e4b7fcdSDave Hansen 14482e4b7fcdSDave Hansen if (readonly_request) 14492e4b7fcdSDave Hansen error = mnt_make_readonly(mnt); 14502e4b7fcdSDave Hansen else 14512e4b7fcdSDave Hansen __mnt_unmake_readonly(mnt); 14522e4b7fcdSDave Hansen return error; 14532e4b7fcdSDave Hansen } 14542e4b7fcdSDave Hansen 14551da177e4SLinus Torvalds /* 14561da177e4SLinus Torvalds * change filesystem flags. dir should be a physical root of filesystem. 14571da177e4SLinus Torvalds * If you've mounted a non-root directory somewhere and want to do remount 14581da177e4SLinus Torvalds * on it - tough luck. 14591da177e4SLinus Torvalds */ 14600a0d8a46SAl Viro static int do_remount(struct path *path, int flags, int mnt_flags, 14611da177e4SLinus Torvalds void *data) 14621da177e4SLinus Torvalds { 14631da177e4SLinus Torvalds int err; 14642d92ab3cSAl Viro struct super_block *sb = path->mnt->mnt_sb; 14651da177e4SLinus Torvalds 14661da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 14671da177e4SLinus Torvalds return -EPERM; 14681da177e4SLinus Torvalds 14692d92ab3cSAl Viro if (!check_mnt(path->mnt)) 14701da177e4SLinus Torvalds return -EINVAL; 14711da177e4SLinus Torvalds 14722d92ab3cSAl Viro if (path->dentry != path->mnt->mnt_root) 14731da177e4SLinus Torvalds return -EINVAL; 14741da177e4SLinus Torvalds 14751da177e4SLinus Torvalds down_write(&sb->s_umount); 14762e4b7fcdSDave Hansen if (flags & MS_BIND) 14772d92ab3cSAl Viro err = change_mount_flags(path->mnt, flags); 14782e4b7fcdSDave Hansen else 14791da177e4SLinus Torvalds err = do_remount_sb(sb, flags, data, 0); 14801da177e4SLinus Torvalds if (!err) 14812d92ab3cSAl Viro path->mnt->mnt_flags = mnt_flags; 14821da177e4SLinus Torvalds up_write(&sb->s_umount); 14830e55a7ccSDan Williams if (!err) { 14842d92ab3cSAl Viro security_sb_post_remount(path->mnt, flags, data); 14850e55a7ccSDan Williams 14860e55a7ccSDan Williams spin_lock(&vfsmount_lock); 14870e55a7ccSDan Williams touch_mnt_namespace(path->mnt->mnt_ns); 14880e55a7ccSDan Williams spin_unlock(&vfsmount_lock); 14890e55a7ccSDan Williams } 14901da177e4SLinus Torvalds return err; 14911da177e4SLinus Torvalds } 14921da177e4SLinus Torvalds 14939676f0c6SRam Pai static inline int tree_contains_unbindable(struct vfsmount *mnt) 14949676f0c6SRam Pai { 14959676f0c6SRam Pai struct vfsmount *p; 14969676f0c6SRam Pai for (p = mnt; p; p = next_mnt(p, mnt)) { 14979676f0c6SRam Pai if (IS_MNT_UNBINDABLE(p)) 14989676f0c6SRam Pai return 1; 14999676f0c6SRam Pai } 15009676f0c6SRam Pai return 0; 15019676f0c6SRam Pai } 15029676f0c6SRam Pai 15030a0d8a46SAl Viro static int do_move_mount(struct path *path, char *old_name) 15041da177e4SLinus Torvalds { 15052d92ab3cSAl Viro struct path old_path, parent_path; 15061da177e4SLinus Torvalds struct vfsmount *p; 15071da177e4SLinus Torvalds int err = 0; 15081da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 15091da177e4SLinus Torvalds return -EPERM; 15101da177e4SLinus Torvalds if (!old_name || !*old_name) 15111da177e4SLinus Torvalds return -EINVAL; 15122d92ab3cSAl Viro err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); 15131da177e4SLinus Torvalds if (err) 15141da177e4SLinus Torvalds return err; 15151da177e4SLinus Torvalds 1516390c6843SRam Pai down_write(&namespace_sem); 15172d92ab3cSAl Viro while (d_mountpoint(path->dentry) && 15189393bd07SAl Viro follow_down(path)) 15191da177e4SLinus Torvalds ; 15201da177e4SLinus Torvalds err = -EINVAL; 15212d92ab3cSAl Viro if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt)) 15221da177e4SLinus Torvalds goto out; 15231da177e4SLinus Torvalds 15241da177e4SLinus Torvalds err = -ENOENT; 15252d92ab3cSAl Viro mutex_lock(&path->dentry->d_inode->i_mutex); 15262d92ab3cSAl Viro if (IS_DEADDIR(path->dentry->d_inode)) 15271da177e4SLinus Torvalds goto out1; 15281da177e4SLinus Torvalds 15292d92ab3cSAl Viro if (!IS_ROOT(path->dentry) && d_unhashed(path->dentry)) 153021444403SRam Pai goto out1; 15311da177e4SLinus Torvalds 15321da177e4SLinus Torvalds err = -EINVAL; 15332d92ab3cSAl Viro if (old_path.dentry != old_path.mnt->mnt_root) 153421444403SRam Pai goto out1; 15351da177e4SLinus Torvalds 15362d92ab3cSAl Viro if (old_path.mnt == old_path.mnt->mnt_parent) 153721444403SRam Pai goto out1; 15381da177e4SLinus Torvalds 15392d92ab3cSAl Viro if (S_ISDIR(path->dentry->d_inode->i_mode) != 15402d92ab3cSAl Viro S_ISDIR(old_path.dentry->d_inode->i_mode)) 154121444403SRam Pai goto out1; 154221444403SRam Pai /* 154321444403SRam Pai * Don't move a mount residing in a shared parent. 154421444403SRam Pai */ 15452d92ab3cSAl Viro if (old_path.mnt->mnt_parent && 15462d92ab3cSAl Viro IS_MNT_SHARED(old_path.mnt->mnt_parent)) 154721444403SRam Pai goto out1; 15489676f0c6SRam Pai /* 15499676f0c6SRam Pai * Don't move a mount tree containing unbindable mounts to a destination 15509676f0c6SRam Pai * mount which is shared. 15519676f0c6SRam Pai */ 15522d92ab3cSAl Viro if (IS_MNT_SHARED(path->mnt) && 15532d92ab3cSAl Viro tree_contains_unbindable(old_path.mnt)) 15549676f0c6SRam Pai goto out1; 15551da177e4SLinus Torvalds err = -ELOOP; 15562d92ab3cSAl Viro for (p = path->mnt; p->mnt_parent != p; p = p->mnt_parent) 15572d92ab3cSAl Viro if (p == old_path.mnt) 155821444403SRam Pai goto out1; 15591da177e4SLinus Torvalds 15602d92ab3cSAl Viro err = attach_recursive_mnt(old_path.mnt, path, &parent_path); 15614ac91378SJan Blunck if (err) 156221444403SRam Pai goto out1; 15631da177e4SLinus Torvalds 15641da177e4SLinus Torvalds /* if the mount is moved, it should no longer be expire 15651da177e4SLinus Torvalds * automatically */ 15662d92ab3cSAl Viro list_del_init(&old_path.mnt->mnt_expire); 15671da177e4SLinus Torvalds out1: 15682d92ab3cSAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 15691da177e4SLinus Torvalds out: 1570390c6843SRam Pai up_write(&namespace_sem); 15711da177e4SLinus Torvalds if (!err) 15721a390689SAl Viro path_put(&parent_path); 15732d92ab3cSAl Viro path_put(&old_path); 15741da177e4SLinus Torvalds return err; 15751da177e4SLinus Torvalds } 15761da177e4SLinus Torvalds 15771da177e4SLinus Torvalds /* 15781da177e4SLinus Torvalds * create a new mount for userspace and request it to be added into the 15791da177e4SLinus Torvalds * namespace's tree 15801da177e4SLinus Torvalds */ 15810a0d8a46SAl Viro static int do_new_mount(struct path *path, char *type, int flags, 15821da177e4SLinus Torvalds int mnt_flags, char *name, void *data) 15831da177e4SLinus Torvalds { 15841da177e4SLinus Torvalds struct vfsmount *mnt; 15851da177e4SLinus Torvalds 15861da177e4SLinus Torvalds if (!type || !memchr(type, 0, PAGE_SIZE)) 15871da177e4SLinus Torvalds return -EINVAL; 15881da177e4SLinus Torvalds 15891da177e4SLinus Torvalds /* we need capabilities... */ 15901da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 15911da177e4SLinus Torvalds return -EPERM; 15921da177e4SLinus Torvalds 15931da177e4SLinus Torvalds mnt = do_kern_mount(type, flags, name, data); 15941da177e4SLinus Torvalds if (IS_ERR(mnt)) 15951da177e4SLinus Torvalds return PTR_ERR(mnt); 15961da177e4SLinus Torvalds 15972d92ab3cSAl Viro return do_add_mount(mnt, path, mnt_flags, NULL); 15981da177e4SLinus Torvalds } 15991da177e4SLinus Torvalds 16001da177e4SLinus Torvalds /* 16011da177e4SLinus Torvalds * add a mount into a namespace's mount tree 16021da177e4SLinus Torvalds * - provide the option of adding the new mount to an expiration list 16031da177e4SLinus Torvalds */ 16048d66bf54SAl Viro int do_add_mount(struct vfsmount *newmnt, struct path *path, 16051da177e4SLinus Torvalds int mnt_flags, struct list_head *fslist) 16061da177e4SLinus Torvalds { 16071da177e4SLinus Torvalds int err; 16081da177e4SLinus Torvalds 1609390c6843SRam Pai down_write(&namespace_sem); 16101da177e4SLinus Torvalds /* Something was mounted here while we slept */ 16118d66bf54SAl Viro while (d_mountpoint(path->dentry) && 16129393bd07SAl Viro follow_down(path)) 16131da177e4SLinus Torvalds ; 16141da177e4SLinus Torvalds err = -EINVAL; 1615dd5cae6eSAl Viro if (!(mnt_flags & MNT_SHRINKABLE) && !check_mnt(path->mnt)) 16161da177e4SLinus Torvalds goto unlock; 16171da177e4SLinus Torvalds 16181da177e4SLinus Torvalds /* Refuse the same filesystem on the same mount point */ 16191da177e4SLinus Torvalds err = -EBUSY; 16208d66bf54SAl Viro if (path->mnt->mnt_sb == newmnt->mnt_sb && 16218d66bf54SAl Viro path->mnt->mnt_root == path->dentry) 16221da177e4SLinus Torvalds goto unlock; 16231da177e4SLinus Torvalds 16241da177e4SLinus Torvalds err = -EINVAL; 16251da177e4SLinus Torvalds if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode)) 16261da177e4SLinus Torvalds goto unlock; 16271da177e4SLinus Torvalds 16281da177e4SLinus Torvalds newmnt->mnt_flags = mnt_flags; 16298d66bf54SAl Viro if ((err = graft_tree(newmnt, path))) 16305b83d2c5SRam Pai goto unlock; 16311da177e4SLinus Torvalds 16326758f953SAl Viro if (fslist) /* add to the specified expiration list */ 163355e700b9SMiklos Szeredi list_add_tail(&newmnt->mnt_expire, fslist); 16346758f953SAl Viro 1635390c6843SRam Pai up_write(&namespace_sem); 16365b83d2c5SRam Pai return 0; 16371da177e4SLinus Torvalds 16381da177e4SLinus Torvalds unlock: 1639390c6843SRam Pai up_write(&namespace_sem); 16401da177e4SLinus Torvalds mntput(newmnt); 16411da177e4SLinus Torvalds return err; 16421da177e4SLinus Torvalds } 16431da177e4SLinus Torvalds 16441da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(do_add_mount); 16451da177e4SLinus Torvalds 16465528f911STrond Myklebust /* 16471da177e4SLinus Torvalds * process a list of expirable mountpoints with the intent of discarding any 16481da177e4SLinus Torvalds * mountpoints that aren't in use and haven't been touched since last we came 16491da177e4SLinus Torvalds * here 16501da177e4SLinus Torvalds */ 16511da177e4SLinus Torvalds void mark_mounts_for_expiry(struct list_head *mounts) 16521da177e4SLinus Torvalds { 16531da177e4SLinus Torvalds struct vfsmount *mnt, *next; 16541da177e4SLinus Torvalds LIST_HEAD(graveyard); 1655bcc5c7d2SAl Viro LIST_HEAD(umounts); 16561da177e4SLinus Torvalds 16571da177e4SLinus Torvalds if (list_empty(mounts)) 16581da177e4SLinus Torvalds return; 16591da177e4SLinus Torvalds 1660bcc5c7d2SAl Viro down_write(&namespace_sem); 16611da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 16621da177e4SLinus Torvalds 16631da177e4SLinus Torvalds /* extract from the expiration list every vfsmount that matches the 16641da177e4SLinus Torvalds * following criteria: 16651da177e4SLinus Torvalds * - only referenced by its parent vfsmount 16661da177e4SLinus Torvalds * - still marked for expiry (marked on the last call here; marks are 16671da177e4SLinus Torvalds * cleared by mntput()) 16681da177e4SLinus Torvalds */ 166955e700b9SMiklos Szeredi list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { 16701da177e4SLinus Torvalds if (!xchg(&mnt->mnt_expiry_mark, 1) || 1671bcc5c7d2SAl Viro propagate_mount_busy(mnt, 1)) 16721da177e4SLinus Torvalds continue; 167355e700b9SMiklos Szeredi list_move(&mnt->mnt_expire, &graveyard); 16741da177e4SLinus Torvalds } 1675bcc5c7d2SAl Viro while (!list_empty(&graveyard)) { 1676bcc5c7d2SAl Viro mnt = list_first_entry(&graveyard, struct vfsmount, mnt_expire); 1677bcc5c7d2SAl Viro touch_mnt_namespace(mnt->mnt_ns); 1678bcc5c7d2SAl Viro umount_tree(mnt, 1, &umounts); 1679bcc5c7d2SAl Viro } 16801da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 1681bcc5c7d2SAl Viro up_write(&namespace_sem); 1682bcc5c7d2SAl Viro 1683bcc5c7d2SAl Viro release_mounts(&umounts); 16841da177e4SLinus Torvalds } 16851da177e4SLinus Torvalds 16861da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); 16871da177e4SLinus Torvalds 16881da177e4SLinus Torvalds /* 16895528f911STrond Myklebust * Ripoff of 'select_parent()' 16905528f911STrond Myklebust * 16915528f911STrond Myklebust * search the list of submounts for a given mountpoint, and move any 16925528f911STrond Myklebust * shrinkable submounts to the 'graveyard' list. 16935528f911STrond Myklebust */ 16945528f911STrond Myklebust static int select_submounts(struct vfsmount *parent, struct list_head *graveyard) 16955528f911STrond Myklebust { 16965528f911STrond Myklebust struct vfsmount *this_parent = parent; 16975528f911STrond Myklebust struct list_head *next; 16985528f911STrond Myklebust int found = 0; 16995528f911STrond Myklebust 17005528f911STrond Myklebust repeat: 17015528f911STrond Myklebust next = this_parent->mnt_mounts.next; 17025528f911STrond Myklebust resume: 17035528f911STrond Myklebust while (next != &this_parent->mnt_mounts) { 17045528f911STrond Myklebust struct list_head *tmp = next; 17055528f911STrond Myklebust struct vfsmount *mnt = list_entry(tmp, struct vfsmount, mnt_child); 17065528f911STrond Myklebust 17075528f911STrond Myklebust next = tmp->next; 17085528f911STrond Myklebust if (!(mnt->mnt_flags & MNT_SHRINKABLE)) 17095528f911STrond Myklebust continue; 17105528f911STrond Myklebust /* 17115528f911STrond Myklebust * Descend a level if the d_mounts list is non-empty. 17125528f911STrond Myklebust */ 17135528f911STrond Myklebust if (!list_empty(&mnt->mnt_mounts)) { 17145528f911STrond Myklebust this_parent = mnt; 17155528f911STrond Myklebust goto repeat; 17165528f911STrond Myklebust } 17175528f911STrond Myklebust 17185528f911STrond Myklebust if (!propagate_mount_busy(mnt, 1)) { 17195528f911STrond Myklebust list_move_tail(&mnt->mnt_expire, graveyard); 17205528f911STrond Myklebust found++; 17215528f911STrond Myklebust } 17225528f911STrond Myklebust } 17235528f911STrond Myklebust /* 17245528f911STrond Myklebust * All done at this level ... ascend and resume the search 17255528f911STrond Myklebust */ 17265528f911STrond Myklebust if (this_parent != parent) { 17275528f911STrond Myklebust next = this_parent->mnt_child.next; 17285528f911STrond Myklebust this_parent = this_parent->mnt_parent; 17295528f911STrond Myklebust goto resume; 17305528f911STrond Myklebust } 17315528f911STrond Myklebust return found; 17325528f911STrond Myklebust } 17335528f911STrond Myklebust 17345528f911STrond Myklebust /* 17355528f911STrond Myklebust * process a list of expirable mountpoints with the intent of discarding any 17365528f911STrond Myklebust * submounts of a specific parent mountpoint 17375528f911STrond Myklebust */ 1738c35038beSAl Viro static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts) 17395528f911STrond Myklebust { 17405528f911STrond Myklebust LIST_HEAD(graveyard); 1741c35038beSAl Viro struct vfsmount *m; 17425528f911STrond Myklebust 17435528f911STrond Myklebust /* extract submounts of 'mountpoint' from the expiration list */ 1744c35038beSAl Viro while (select_submounts(mnt, &graveyard)) { 1745bcc5c7d2SAl Viro while (!list_empty(&graveyard)) { 1746c35038beSAl Viro m = list_first_entry(&graveyard, struct vfsmount, 1747bcc5c7d2SAl Viro mnt_expire); 1748afef80b3SEric W. Biederman touch_mnt_namespace(m->mnt_ns); 1749afef80b3SEric W. Biederman umount_tree(m, 1, umounts); 1750bcc5c7d2SAl Viro } 1751bcc5c7d2SAl Viro } 17525528f911STrond Myklebust } 17535528f911STrond Myklebust 17545528f911STrond Myklebust /* 17551da177e4SLinus Torvalds * Some copy_from_user() implementations do not return the exact number of 17561da177e4SLinus Torvalds * bytes remaining to copy on a fault. But copy_mount_options() requires that. 17571da177e4SLinus Torvalds * Note that this function differs from copy_from_user() in that it will oops 17581da177e4SLinus Torvalds * on bad values of `to', rather than returning a short copy. 17591da177e4SLinus Torvalds */ 1760b58fed8bSRam Pai static long exact_copy_from_user(void *to, const void __user * from, 1761b58fed8bSRam Pai unsigned long n) 17621da177e4SLinus Torvalds { 17631da177e4SLinus Torvalds char *t = to; 17641da177e4SLinus Torvalds const char __user *f = from; 17651da177e4SLinus Torvalds char c; 17661da177e4SLinus Torvalds 17671da177e4SLinus Torvalds if (!access_ok(VERIFY_READ, from, n)) 17681da177e4SLinus Torvalds return n; 17691da177e4SLinus Torvalds 17701da177e4SLinus Torvalds while (n) { 17711da177e4SLinus Torvalds if (__get_user(c, f)) { 17721da177e4SLinus Torvalds memset(t, 0, n); 17731da177e4SLinus Torvalds break; 17741da177e4SLinus Torvalds } 17751da177e4SLinus Torvalds *t++ = c; 17761da177e4SLinus Torvalds f++; 17771da177e4SLinus Torvalds n--; 17781da177e4SLinus Torvalds } 17791da177e4SLinus Torvalds return n; 17801da177e4SLinus Torvalds } 17811da177e4SLinus Torvalds 17821da177e4SLinus Torvalds int copy_mount_options(const void __user * data, unsigned long *where) 17831da177e4SLinus Torvalds { 17841da177e4SLinus Torvalds int i; 17851da177e4SLinus Torvalds unsigned long page; 17861da177e4SLinus Torvalds unsigned long size; 17871da177e4SLinus Torvalds 17881da177e4SLinus Torvalds *where = 0; 17891da177e4SLinus Torvalds if (!data) 17901da177e4SLinus Torvalds return 0; 17911da177e4SLinus Torvalds 17921da177e4SLinus Torvalds if (!(page = __get_free_page(GFP_KERNEL))) 17931da177e4SLinus Torvalds return -ENOMEM; 17941da177e4SLinus Torvalds 17951da177e4SLinus Torvalds /* We only care that *some* data at the address the user 17961da177e4SLinus Torvalds * gave us is valid. Just in case, we'll zero 17971da177e4SLinus Torvalds * the remainder of the page. 17981da177e4SLinus Torvalds */ 17991da177e4SLinus Torvalds /* copy_from_user cannot cross TASK_SIZE ! */ 18001da177e4SLinus Torvalds size = TASK_SIZE - (unsigned long)data; 18011da177e4SLinus Torvalds if (size > PAGE_SIZE) 18021da177e4SLinus Torvalds size = PAGE_SIZE; 18031da177e4SLinus Torvalds 18041da177e4SLinus Torvalds i = size - exact_copy_from_user((void *)page, data, size); 18051da177e4SLinus Torvalds if (!i) { 18061da177e4SLinus Torvalds free_page(page); 18071da177e4SLinus Torvalds return -EFAULT; 18081da177e4SLinus Torvalds } 18091da177e4SLinus Torvalds if (i != PAGE_SIZE) 18101da177e4SLinus Torvalds memset((char *)page + i, 0, PAGE_SIZE - i); 18111da177e4SLinus Torvalds *where = page; 18121da177e4SLinus Torvalds return 0; 18131da177e4SLinus Torvalds } 18141da177e4SLinus Torvalds 18151da177e4SLinus Torvalds /* 18161da177e4SLinus Torvalds * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to 18171da177e4SLinus Torvalds * be given to the mount() call (ie: read-only, no-dev, no-suid etc). 18181da177e4SLinus Torvalds * 18191da177e4SLinus Torvalds * data is a (void *) that can point to any structure up to 18201da177e4SLinus Torvalds * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent 18211da177e4SLinus Torvalds * information (or be NULL). 18221da177e4SLinus Torvalds * 18231da177e4SLinus Torvalds * Pre-0.97 versions of mount() didn't have a flags word. 18241da177e4SLinus Torvalds * When the flags word was introduced its top half was required 18251da177e4SLinus Torvalds * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. 18261da177e4SLinus Torvalds * Therefore, if this magic number is present, it carries no information 18271da177e4SLinus Torvalds * and must be discarded. 18281da177e4SLinus Torvalds */ 18291da177e4SLinus Torvalds long do_mount(char *dev_name, char *dir_name, char *type_page, 18301da177e4SLinus Torvalds unsigned long flags, void *data_page) 18311da177e4SLinus Torvalds { 18322d92ab3cSAl Viro struct path path; 18331da177e4SLinus Torvalds int retval = 0; 18341da177e4SLinus Torvalds int mnt_flags = 0; 18351da177e4SLinus Torvalds 18361da177e4SLinus Torvalds /* Discard magic */ 18371da177e4SLinus Torvalds if ((flags & MS_MGC_MSK) == MS_MGC_VAL) 18381da177e4SLinus Torvalds flags &= ~MS_MGC_MSK; 18391da177e4SLinus Torvalds 18401da177e4SLinus Torvalds /* Basic sanity checks */ 18411da177e4SLinus Torvalds 18421da177e4SLinus Torvalds if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) 18431da177e4SLinus Torvalds return -EINVAL; 18441da177e4SLinus Torvalds if (dev_name && !memchr(dev_name, 0, PAGE_SIZE)) 18451da177e4SLinus Torvalds return -EINVAL; 18461da177e4SLinus Torvalds 18471da177e4SLinus Torvalds if (data_page) 18481da177e4SLinus Torvalds ((char *)data_page)[PAGE_SIZE - 1] = 0; 18491da177e4SLinus Torvalds 1850613cbe3dSAndi Kleen /* Default to relatime unless overriden */ 1851613cbe3dSAndi Kleen if (!(flags & MS_NOATIME)) 18520a1c01c9SMatthew Garrett mnt_flags |= MNT_RELATIME; 18530a1c01c9SMatthew Garrett 18541da177e4SLinus Torvalds /* Separate the per-mountpoint flags */ 18551da177e4SLinus Torvalds if (flags & MS_NOSUID) 18561da177e4SLinus Torvalds mnt_flags |= MNT_NOSUID; 18571da177e4SLinus Torvalds if (flags & MS_NODEV) 18581da177e4SLinus Torvalds mnt_flags |= MNT_NODEV; 18591da177e4SLinus Torvalds if (flags & MS_NOEXEC) 18601da177e4SLinus Torvalds mnt_flags |= MNT_NOEXEC; 1861fc33a7bbSChristoph Hellwig if (flags & MS_NOATIME) 1862fc33a7bbSChristoph Hellwig mnt_flags |= MNT_NOATIME; 1863fc33a7bbSChristoph Hellwig if (flags & MS_NODIRATIME) 1864fc33a7bbSChristoph Hellwig mnt_flags |= MNT_NODIRATIME; 1865d0adde57SMatthew Garrett if (flags & MS_STRICTATIME) 1866d0adde57SMatthew Garrett mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME); 18672e4b7fcdSDave Hansen if (flags & MS_RDONLY) 18682e4b7fcdSDave Hansen mnt_flags |= MNT_READONLY; 1869fc33a7bbSChristoph Hellwig 1870fc33a7bbSChristoph Hellwig flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | 1871d0adde57SMatthew Garrett MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT | 1872d0adde57SMatthew Garrett MS_STRICTATIME); 18731da177e4SLinus Torvalds 18741da177e4SLinus Torvalds /* ... and get the mountpoint */ 18752d92ab3cSAl Viro retval = kern_path(dir_name, LOOKUP_FOLLOW, &path); 18761da177e4SLinus Torvalds if (retval) 18771da177e4SLinus Torvalds return retval; 18781da177e4SLinus Torvalds 18792d92ab3cSAl Viro retval = security_sb_mount(dev_name, &path, 1880b5266eb4SAl Viro type_page, flags, data_page); 18811da177e4SLinus Torvalds if (retval) 18821da177e4SLinus Torvalds goto dput_out; 18831da177e4SLinus Torvalds 18841da177e4SLinus Torvalds if (flags & MS_REMOUNT) 18852d92ab3cSAl Viro retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags, 18861da177e4SLinus Torvalds data_page); 18871da177e4SLinus Torvalds else if (flags & MS_BIND) 18882d92ab3cSAl Viro retval = do_loopback(&path, dev_name, flags & MS_REC); 18899676f0c6SRam Pai else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) 18902d92ab3cSAl Viro retval = do_change_type(&path, flags); 18911da177e4SLinus Torvalds else if (flags & MS_MOVE) 18922d92ab3cSAl Viro retval = do_move_mount(&path, dev_name); 18931da177e4SLinus Torvalds else 18942d92ab3cSAl Viro retval = do_new_mount(&path, type_page, flags, mnt_flags, 18951da177e4SLinus Torvalds dev_name, data_page); 18961da177e4SLinus Torvalds dput_out: 18972d92ab3cSAl Viro path_put(&path); 18981da177e4SLinus Torvalds return retval; 18991da177e4SLinus Torvalds } 19001da177e4SLinus Torvalds 1901741a2951SJANAK DESAI /* 1902741a2951SJANAK DESAI * Allocate a new namespace structure and populate it with contents 1903741a2951SJANAK DESAI * copied from the namespace of the passed in task structure. 1904741a2951SJANAK DESAI */ 1905e3222c4eSBadari Pulavarty static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, 19066b3286edSKirill Korotaev struct fs_struct *fs) 19071da177e4SLinus Torvalds { 19086b3286edSKirill Korotaev struct mnt_namespace *new_ns; 19097f2da1e7SAl Viro struct vfsmount *rootmnt = NULL, *pwdmnt = NULL; 19101da177e4SLinus Torvalds struct vfsmount *p, *q; 19111da177e4SLinus Torvalds 19126b3286edSKirill Korotaev new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL); 19131da177e4SLinus Torvalds if (!new_ns) 1914467e9f4bSCedric Le Goater return ERR_PTR(-ENOMEM); 19151da177e4SLinus Torvalds 19161da177e4SLinus Torvalds atomic_set(&new_ns->count, 1); 19171da177e4SLinus Torvalds INIT_LIST_HEAD(&new_ns->list); 19185addc5ddSAl Viro init_waitqueue_head(&new_ns->poll); 19195addc5ddSAl Viro new_ns->event = 0; 19201da177e4SLinus Torvalds 1921390c6843SRam Pai down_write(&namespace_sem); 19221da177e4SLinus Torvalds /* First pass: copy the tree topology */ 19236b3286edSKirill Korotaev new_ns->root = copy_tree(mnt_ns->root, mnt_ns->root->mnt_root, 19249676f0c6SRam Pai CL_COPY_ALL | CL_EXPIRE); 19251da177e4SLinus Torvalds if (!new_ns->root) { 1926390c6843SRam Pai up_write(&namespace_sem); 19271da177e4SLinus Torvalds kfree(new_ns); 19285cc4a034SJulia Lawall return ERR_PTR(-ENOMEM); 19291da177e4SLinus Torvalds } 19301da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 19311da177e4SLinus Torvalds list_add_tail(&new_ns->list, &new_ns->root->mnt_list); 19321da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 19331da177e4SLinus Torvalds 19341da177e4SLinus Torvalds /* 19351da177e4SLinus Torvalds * Second pass: switch the tsk->fs->* elements and mark new vfsmounts 19361da177e4SLinus Torvalds * as belonging to new namespace. We have already acquired a private 19371da177e4SLinus Torvalds * fs_struct, so tsk->fs->lock is not needed. 19381da177e4SLinus Torvalds */ 19396b3286edSKirill Korotaev p = mnt_ns->root; 19401da177e4SLinus Torvalds q = new_ns->root; 19411da177e4SLinus Torvalds while (p) { 19426b3286edSKirill Korotaev q->mnt_ns = new_ns; 19431da177e4SLinus Torvalds if (fs) { 19446ac08c39SJan Blunck if (p == fs->root.mnt) { 19451da177e4SLinus Torvalds rootmnt = p; 19466ac08c39SJan Blunck fs->root.mnt = mntget(q); 19471da177e4SLinus Torvalds } 19486ac08c39SJan Blunck if (p == fs->pwd.mnt) { 19491da177e4SLinus Torvalds pwdmnt = p; 19506ac08c39SJan Blunck fs->pwd.mnt = mntget(q); 19511da177e4SLinus Torvalds } 19521da177e4SLinus Torvalds } 19536b3286edSKirill Korotaev p = next_mnt(p, mnt_ns->root); 19541da177e4SLinus Torvalds q = next_mnt(q, new_ns->root); 19551da177e4SLinus Torvalds } 1956390c6843SRam Pai up_write(&namespace_sem); 19571da177e4SLinus Torvalds 19581da177e4SLinus Torvalds if (rootmnt) 19591da177e4SLinus Torvalds mntput(rootmnt); 19601da177e4SLinus Torvalds if (pwdmnt) 19611da177e4SLinus Torvalds mntput(pwdmnt); 19621da177e4SLinus Torvalds 1963741a2951SJANAK DESAI return new_ns; 1964741a2951SJANAK DESAI } 1965741a2951SJANAK DESAI 1966213dd266SEric W. Biederman struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, 1967e3222c4eSBadari Pulavarty struct fs_struct *new_fs) 1968741a2951SJANAK DESAI { 19696b3286edSKirill Korotaev struct mnt_namespace *new_ns; 1970741a2951SJANAK DESAI 1971e3222c4eSBadari Pulavarty BUG_ON(!ns); 19726b3286edSKirill Korotaev get_mnt_ns(ns); 1973741a2951SJANAK DESAI 1974741a2951SJANAK DESAI if (!(flags & CLONE_NEWNS)) 1975e3222c4eSBadari Pulavarty return ns; 1976741a2951SJANAK DESAI 1977e3222c4eSBadari Pulavarty new_ns = dup_mnt_ns(ns, new_fs); 1978741a2951SJANAK DESAI 19796b3286edSKirill Korotaev put_mnt_ns(ns); 1980e3222c4eSBadari Pulavarty return new_ns; 19811da177e4SLinus Torvalds } 19821da177e4SLinus Torvalds 1983bdc480e3SHeiko Carstens SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, 1984bdc480e3SHeiko Carstens char __user *, type, unsigned long, flags, void __user *, data) 19851da177e4SLinus Torvalds { 19861da177e4SLinus Torvalds int retval; 19871da177e4SLinus Torvalds unsigned long data_page; 19881da177e4SLinus Torvalds unsigned long type_page; 19891da177e4SLinus Torvalds unsigned long dev_page; 19901da177e4SLinus Torvalds char *dir_page; 19911da177e4SLinus Torvalds 19921da177e4SLinus Torvalds retval = copy_mount_options(type, &type_page); 19931da177e4SLinus Torvalds if (retval < 0) 19941da177e4SLinus Torvalds return retval; 19951da177e4SLinus Torvalds 19961da177e4SLinus Torvalds dir_page = getname(dir_name); 19971da177e4SLinus Torvalds retval = PTR_ERR(dir_page); 19981da177e4SLinus Torvalds if (IS_ERR(dir_page)) 19991da177e4SLinus Torvalds goto out1; 20001da177e4SLinus Torvalds 20011da177e4SLinus Torvalds retval = copy_mount_options(dev_name, &dev_page); 20021da177e4SLinus Torvalds if (retval < 0) 20031da177e4SLinus Torvalds goto out2; 20041da177e4SLinus Torvalds 20051da177e4SLinus Torvalds retval = copy_mount_options(data, &data_page); 20061da177e4SLinus Torvalds if (retval < 0) 20071da177e4SLinus Torvalds goto out3; 20081da177e4SLinus Torvalds 20091da177e4SLinus Torvalds lock_kernel(); 20101da177e4SLinus Torvalds retval = do_mount((char *)dev_page, dir_page, (char *)type_page, 20111da177e4SLinus Torvalds flags, (void *)data_page); 20121da177e4SLinus Torvalds unlock_kernel(); 20131da177e4SLinus Torvalds free_page(data_page); 20141da177e4SLinus Torvalds 20151da177e4SLinus Torvalds out3: 20161da177e4SLinus Torvalds free_page(dev_page); 20171da177e4SLinus Torvalds out2: 20181da177e4SLinus Torvalds putname(dir_page); 20191da177e4SLinus Torvalds out1: 20201da177e4SLinus Torvalds free_page(type_page); 20211da177e4SLinus Torvalds return retval; 20221da177e4SLinus Torvalds } 20231da177e4SLinus Torvalds 20241da177e4SLinus Torvalds /* 20251da177e4SLinus Torvalds * pivot_root Semantics: 20261da177e4SLinus Torvalds * Moves the root file system of the current process to the directory put_old, 20271da177e4SLinus Torvalds * makes new_root as the new root file system of the current process, and sets 20281da177e4SLinus Torvalds * root/cwd of all processes which had them on the current root to new_root. 20291da177e4SLinus Torvalds * 20301da177e4SLinus Torvalds * Restrictions: 20311da177e4SLinus Torvalds * The new_root and put_old must be directories, and must not be on the 20321da177e4SLinus Torvalds * same file system as the current process root. The put_old must be 20331da177e4SLinus Torvalds * underneath new_root, i.e. adding a non-zero number of /.. to the string 20341da177e4SLinus Torvalds * pointed to by put_old must yield the same directory as new_root. No other 20351da177e4SLinus Torvalds * file system may be mounted on put_old. After all, new_root is a mountpoint. 20361da177e4SLinus Torvalds * 20374a0d11faSNeil Brown * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. 20384a0d11faSNeil Brown * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives 20394a0d11faSNeil Brown * in this situation. 20404a0d11faSNeil Brown * 20411da177e4SLinus Torvalds * Notes: 20421da177e4SLinus Torvalds * - we don't move root/cwd if they are not at the root (reason: if something 20431da177e4SLinus Torvalds * cared enough to change them, it's probably wrong to force them elsewhere) 20441da177e4SLinus Torvalds * - it's okay to pick a root that isn't the root of a file system, e.g. 20451da177e4SLinus Torvalds * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, 20461da177e4SLinus Torvalds * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root 20471da177e4SLinus Torvalds * first. 20481da177e4SLinus Torvalds */ 20493480b257SHeiko Carstens SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, 20503480b257SHeiko Carstens const char __user *, put_old) 20511da177e4SLinus Torvalds { 20521da177e4SLinus Torvalds struct vfsmount *tmp; 20532d8f3038SAl Viro struct path new, old, parent_path, root_parent, root; 20541da177e4SLinus Torvalds int error; 20551da177e4SLinus Torvalds 20561da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 20571da177e4SLinus Torvalds return -EPERM; 20581da177e4SLinus Torvalds 20592d8f3038SAl Viro error = user_path_dir(new_root, &new); 20601da177e4SLinus Torvalds if (error) 20611da177e4SLinus Torvalds goto out0; 20621da177e4SLinus Torvalds error = -EINVAL; 20632d8f3038SAl Viro if (!check_mnt(new.mnt)) 20641da177e4SLinus Torvalds goto out1; 20651da177e4SLinus Torvalds 20662d8f3038SAl Viro error = user_path_dir(put_old, &old); 20671da177e4SLinus Torvalds if (error) 20681da177e4SLinus Torvalds goto out1; 20691da177e4SLinus Torvalds 20702d8f3038SAl Viro error = security_sb_pivotroot(&old, &new); 20711da177e4SLinus Torvalds if (error) { 20722d8f3038SAl Viro path_put(&old); 20731da177e4SLinus Torvalds goto out1; 20741da177e4SLinus Torvalds } 20751da177e4SLinus Torvalds 20761da177e4SLinus Torvalds read_lock(¤t->fs->lock); 20778c3ee42eSAl Viro root = current->fs->root; 20786ac08c39SJan Blunck path_get(¤t->fs->root); 20791da177e4SLinus Torvalds read_unlock(¤t->fs->lock); 2080390c6843SRam Pai down_write(&namespace_sem); 20812d8f3038SAl Viro mutex_lock(&old.dentry->d_inode->i_mutex); 20821da177e4SLinus Torvalds error = -EINVAL; 20832d8f3038SAl Viro if (IS_MNT_SHARED(old.mnt) || 20842d8f3038SAl Viro IS_MNT_SHARED(new.mnt->mnt_parent) || 20858c3ee42eSAl Viro IS_MNT_SHARED(root.mnt->mnt_parent)) 208621444403SRam Pai goto out2; 20878c3ee42eSAl Viro if (!check_mnt(root.mnt)) 20881da177e4SLinus Torvalds goto out2; 20891da177e4SLinus Torvalds error = -ENOENT; 20902d8f3038SAl Viro if (IS_DEADDIR(new.dentry->d_inode)) 20911da177e4SLinus Torvalds goto out2; 20922d8f3038SAl Viro if (d_unhashed(new.dentry) && !IS_ROOT(new.dentry)) 20931da177e4SLinus Torvalds goto out2; 20942d8f3038SAl Viro if (d_unhashed(old.dentry) && !IS_ROOT(old.dentry)) 20951da177e4SLinus Torvalds goto out2; 20961da177e4SLinus Torvalds error = -EBUSY; 20972d8f3038SAl Viro if (new.mnt == root.mnt || 20982d8f3038SAl Viro old.mnt == root.mnt) 20991da177e4SLinus Torvalds goto out2; /* loop, on the same file system */ 21001da177e4SLinus Torvalds error = -EINVAL; 21018c3ee42eSAl Viro if (root.mnt->mnt_root != root.dentry) 21021da177e4SLinus Torvalds goto out2; /* not a mountpoint */ 21038c3ee42eSAl Viro if (root.mnt->mnt_parent == root.mnt) 21040bb6fcc1SMiklos Szeredi goto out2; /* not attached */ 21052d8f3038SAl Viro if (new.mnt->mnt_root != new.dentry) 21061da177e4SLinus Torvalds goto out2; /* not a mountpoint */ 21072d8f3038SAl Viro if (new.mnt->mnt_parent == new.mnt) 21080bb6fcc1SMiklos Szeredi goto out2; /* not attached */ 21094ac91378SJan Blunck /* make sure we can reach put_old from new_root */ 21102d8f3038SAl Viro tmp = old.mnt; 21111da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 21122d8f3038SAl Viro if (tmp != new.mnt) { 21131da177e4SLinus Torvalds for (;;) { 21141da177e4SLinus Torvalds if (tmp->mnt_parent == tmp) 21151da177e4SLinus Torvalds goto out3; /* already mounted on put_old */ 21162d8f3038SAl Viro if (tmp->mnt_parent == new.mnt) 21171da177e4SLinus Torvalds break; 21181da177e4SLinus Torvalds tmp = tmp->mnt_parent; 21191da177e4SLinus Torvalds } 21202d8f3038SAl Viro if (!is_subdir(tmp->mnt_mountpoint, new.dentry)) 21211da177e4SLinus Torvalds goto out3; 21222d8f3038SAl Viro } else if (!is_subdir(old.dentry, new.dentry)) 21231da177e4SLinus Torvalds goto out3; 21242d8f3038SAl Viro detach_mnt(new.mnt, &parent_path); 21258c3ee42eSAl Viro detach_mnt(root.mnt, &root_parent); 21264ac91378SJan Blunck /* mount old root on put_old */ 21272d8f3038SAl Viro attach_mnt(root.mnt, &old); 21284ac91378SJan Blunck /* mount new_root on / */ 21292d8f3038SAl Viro attach_mnt(new.mnt, &root_parent); 21306b3286edSKirill Korotaev touch_mnt_namespace(current->nsproxy->mnt_ns); 21311da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 21322d8f3038SAl Viro chroot_fs_refs(&root, &new); 21332d8f3038SAl Viro security_sb_post_pivotroot(&root, &new); 21341da177e4SLinus Torvalds error = 0; 21351a390689SAl Viro path_put(&root_parent); 21361a390689SAl Viro path_put(&parent_path); 21371da177e4SLinus Torvalds out2: 21382d8f3038SAl Viro mutex_unlock(&old.dentry->d_inode->i_mutex); 2139390c6843SRam Pai up_write(&namespace_sem); 21408c3ee42eSAl Viro path_put(&root); 21412d8f3038SAl Viro path_put(&old); 21421da177e4SLinus Torvalds out1: 21432d8f3038SAl Viro path_put(&new); 21441da177e4SLinus Torvalds out0: 21451da177e4SLinus Torvalds return error; 21461da177e4SLinus Torvalds out3: 21471da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 21481da177e4SLinus Torvalds goto out2; 21491da177e4SLinus Torvalds } 21501da177e4SLinus Torvalds 21511da177e4SLinus Torvalds static void __init init_mount_tree(void) 21521da177e4SLinus Torvalds { 21531da177e4SLinus Torvalds struct vfsmount *mnt; 21546b3286edSKirill Korotaev struct mnt_namespace *ns; 2155ac748a09SJan Blunck struct path root; 21561da177e4SLinus Torvalds 21571da177e4SLinus Torvalds mnt = do_kern_mount("rootfs", 0, "rootfs", NULL); 21581da177e4SLinus Torvalds if (IS_ERR(mnt)) 21591da177e4SLinus Torvalds panic("Can't create rootfs"); 21606b3286edSKirill Korotaev ns = kmalloc(sizeof(*ns), GFP_KERNEL); 21616b3286edSKirill Korotaev if (!ns) 21621da177e4SLinus Torvalds panic("Can't allocate initial namespace"); 21636b3286edSKirill Korotaev atomic_set(&ns->count, 1); 21646b3286edSKirill Korotaev INIT_LIST_HEAD(&ns->list); 21656b3286edSKirill Korotaev init_waitqueue_head(&ns->poll); 21666b3286edSKirill Korotaev ns->event = 0; 21676b3286edSKirill Korotaev list_add(&mnt->mnt_list, &ns->list); 21686b3286edSKirill Korotaev ns->root = mnt; 21696b3286edSKirill Korotaev mnt->mnt_ns = ns; 21701da177e4SLinus Torvalds 21716b3286edSKirill Korotaev init_task.nsproxy->mnt_ns = ns; 21726b3286edSKirill Korotaev get_mnt_ns(ns); 21731da177e4SLinus Torvalds 2174ac748a09SJan Blunck root.mnt = ns->root; 2175ac748a09SJan Blunck root.dentry = ns->root->mnt_root; 2176ac748a09SJan Blunck 2177ac748a09SJan Blunck set_fs_pwd(current->fs, &root); 2178ac748a09SJan Blunck set_fs_root(current->fs, &root); 21791da177e4SLinus Torvalds } 21801da177e4SLinus Torvalds 218174bf17cfSDenis Cheng void __init mnt_init(void) 21821da177e4SLinus Torvalds { 218313f14b4dSEric Dumazet unsigned u; 218415a67dd8SRandy Dunlap int err; 21851da177e4SLinus Torvalds 2186390c6843SRam Pai init_rwsem(&namespace_sem); 2187390c6843SRam Pai 21881da177e4SLinus Torvalds mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount), 218920c2df83SPaul Mundt 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); 21901da177e4SLinus Torvalds 2191b58fed8bSRam Pai mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); 21921da177e4SLinus Torvalds 21931da177e4SLinus Torvalds if (!mount_hashtable) 21941da177e4SLinus Torvalds panic("Failed to allocate mount hash table\n"); 21951da177e4SLinus Torvalds 219613f14b4dSEric Dumazet printk("Mount-cache hash table entries: %lu\n", HASH_SIZE); 21971da177e4SLinus Torvalds 219813f14b4dSEric Dumazet for (u = 0; u < HASH_SIZE; u++) 219913f14b4dSEric Dumazet INIT_LIST_HEAD(&mount_hashtable[u]); 22001da177e4SLinus Torvalds 220115a67dd8SRandy Dunlap err = sysfs_init(); 220215a67dd8SRandy Dunlap if (err) 220315a67dd8SRandy Dunlap printk(KERN_WARNING "%s: sysfs_init error: %d\n", 22048e24eea7SHarvey Harrison __func__, err); 220500d26666SGreg Kroah-Hartman fs_kobj = kobject_create_and_add("fs", NULL); 220600d26666SGreg Kroah-Hartman if (!fs_kobj) 22078e24eea7SHarvey Harrison printk(KERN_WARNING "%s: kobj create error\n", __func__); 22081da177e4SLinus Torvalds init_rootfs(); 22091da177e4SLinus Torvalds init_mount_tree(); 22101da177e4SLinus Torvalds } 22111da177e4SLinus Torvalds 22126b3286edSKirill Korotaev void __put_mnt_ns(struct mnt_namespace *ns) 22131da177e4SLinus Torvalds { 22146b3286edSKirill Korotaev struct vfsmount *root = ns->root; 221570fbcdf4SRam Pai LIST_HEAD(umount_list); 22166b3286edSKirill Korotaev ns->root = NULL; 22171ce88cf4SMiklos Szeredi spin_unlock(&vfsmount_lock); 2218390c6843SRam Pai down_write(&namespace_sem); 22191da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 2220a05964f3SRam Pai umount_tree(root, 0, &umount_list); 22211da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 2222390c6843SRam Pai up_write(&namespace_sem); 222370fbcdf4SRam Pai release_mounts(&umount_list); 22246b3286edSKirill Korotaev kfree(ns); 22251da177e4SLinus Torvalds } 2226