13ad20fe3SChristian Brauner /* SPDX-License-Identifier: GPL-2.0 */ 23ad20fe3SChristian Brauner 33ad20fe3SChristian Brauner #include <linux/compiler_types.h> 43ad20fe3SChristian Brauner #include <linux/errno.h> 53ad20fe3SChristian Brauner #include <linux/fs.h> 63ad20fe3SChristian Brauner #include <linux/fsnotify.h> 73ad20fe3SChristian Brauner #include <linux/gfp.h> 83ad20fe3SChristian Brauner #include <linux/idr.h> 93ad20fe3SChristian Brauner #include <linux/init.h> 103ad20fe3SChristian Brauner #include <linux/ipc_namespace.h> 113ad20fe3SChristian Brauner #include <linux/kdev_t.h> 123ad20fe3SChristian Brauner #include <linux/kernel.h> 133ad20fe3SChristian Brauner #include <linux/list.h> 1401b3f1fcSChristian Brauner #include <linux/namei.h> 153ad20fe3SChristian Brauner #include <linux/magic.h> 163ad20fe3SChristian Brauner #include <linux/major.h> 173ad20fe3SChristian Brauner #include <linux/miscdevice.h> 183ad20fe3SChristian Brauner #include <linux/module.h> 193ad20fe3SChristian Brauner #include <linux/mutex.h> 203ad20fe3SChristian Brauner #include <linux/mount.h> 213ad20fe3SChristian Brauner #include <linux/parser.h> 223ad20fe3SChristian Brauner #include <linux/radix-tree.h> 233ad20fe3SChristian Brauner #include <linux/sched.h> 24849d540dSChristian Brauner #include <linux/seq_file.h> 253ad20fe3SChristian Brauner #include <linux/slab.h> 263ad20fe3SChristian Brauner #include <linux/spinlock_types.h> 273ad20fe3SChristian Brauner #include <linux/stddef.h> 283ad20fe3SChristian Brauner #include <linux/string.h> 293ad20fe3SChristian Brauner #include <linux/types.h> 303ad20fe3SChristian Brauner #include <linux/uaccess.h> 313ad20fe3SChristian Brauner #include <linux/user_namespace.h> 323ad20fe3SChristian Brauner #include <linux/xarray.h> 333ad20fe3SChristian Brauner #include <uapi/asm-generic/errno-base.h> 343ad20fe3SChristian Brauner #include <uapi/linux/android/binder.h> 35c13295adSChristian Brauner #include <uapi/linux/android/binderfs.h> 363ad20fe3SChristian Brauner 373ad20fe3SChristian Brauner #include "binder_internal.h" 383ad20fe3SChristian Brauner 393ad20fe3SChristian Brauner #define FIRST_INODE 1 403ad20fe3SChristian Brauner #define SECOND_INODE 2 413ad20fe3SChristian Brauner #define INODE_OFFSET 3 423ad20fe3SChristian Brauner #define INTSTRLEN 21 433ad20fe3SChristian Brauner #define BINDERFS_MAX_MINOR (1U << MINORBITS) 4436bdf3caSChristian Brauner /* Ensure that the initial ipc namespace always has devices available. */ 4536bdf3caSChristian Brauner #define BINDERFS_MAX_MINOR_CAPPED (BINDERFS_MAX_MINOR - 4) 463ad20fe3SChristian Brauner 473ad20fe3SChristian Brauner static dev_t binderfs_dev; 483ad20fe3SChristian Brauner static DEFINE_MUTEX(binderfs_minors_mutex); 493ad20fe3SChristian Brauner static DEFINE_IDA(binderfs_minors); 503ad20fe3SChristian Brauner 513ad20fe3SChristian Brauner /** 52849d540dSChristian Brauner * binderfs_mount_opts - mount options for binderfs 53849d540dSChristian Brauner * @max: maximum number of allocatable binderfs binder devices 54849d540dSChristian Brauner */ 55849d540dSChristian Brauner struct binderfs_mount_opts { 56849d540dSChristian Brauner int max; 57849d540dSChristian Brauner }; 58849d540dSChristian Brauner 59849d540dSChristian Brauner enum { 60849d540dSChristian Brauner Opt_max, 61849d540dSChristian Brauner Opt_err 62849d540dSChristian Brauner }; 63849d540dSChristian Brauner 64849d540dSChristian Brauner static const match_table_t tokens = { 65849d540dSChristian Brauner { Opt_max, "max=%d" }, 66849d540dSChristian Brauner { Opt_err, NULL } 67849d540dSChristian Brauner }; 68849d540dSChristian Brauner 69849d540dSChristian Brauner /** 703ad20fe3SChristian Brauner * binderfs_info - information about a binderfs mount 713ad20fe3SChristian Brauner * @ipc_ns: The ipc namespace the binderfs mount belongs to. 723ad20fe3SChristian Brauner * @control_dentry: This records the dentry of this binderfs mount 733ad20fe3SChristian Brauner * binder-control device. 743ad20fe3SChristian Brauner * @root_uid: uid that needs to be used when a new binder device is 753ad20fe3SChristian Brauner * created. 763ad20fe3SChristian Brauner * @root_gid: gid that needs to be used when a new binder device is 773ad20fe3SChristian Brauner * created. 78849d540dSChristian Brauner * @mount_opts: The mount options in use. 79849d540dSChristian Brauner * @device_count: The current number of allocated binder devices. 803ad20fe3SChristian Brauner */ 813ad20fe3SChristian Brauner struct binderfs_info { 823ad20fe3SChristian Brauner struct ipc_namespace *ipc_ns; 833ad20fe3SChristian Brauner struct dentry *control_dentry; 843ad20fe3SChristian Brauner kuid_t root_uid; 853ad20fe3SChristian Brauner kgid_t root_gid; 86849d540dSChristian Brauner struct binderfs_mount_opts mount_opts; 87849d540dSChristian Brauner int device_count; 883ad20fe3SChristian Brauner }; 893ad20fe3SChristian Brauner 903ad20fe3SChristian Brauner static inline struct binderfs_info *BINDERFS_I(const struct inode *inode) 913ad20fe3SChristian Brauner { 923ad20fe3SChristian Brauner return inode->i_sb->s_fs_info; 933ad20fe3SChristian Brauner } 943ad20fe3SChristian Brauner 953ad20fe3SChristian Brauner bool is_binderfs_device(const struct inode *inode) 963ad20fe3SChristian Brauner { 973ad20fe3SChristian Brauner if (inode->i_sb->s_magic == BINDERFS_SUPER_MAGIC) 983ad20fe3SChristian Brauner return true; 993ad20fe3SChristian Brauner 1003ad20fe3SChristian Brauner return false; 1013ad20fe3SChristian Brauner } 1023ad20fe3SChristian Brauner 1033ad20fe3SChristian Brauner /** 1043ad20fe3SChristian Brauner * binderfs_binder_device_create - allocate inode from super block of a 1053ad20fe3SChristian Brauner * binderfs mount 1063ad20fe3SChristian Brauner * @ref_inode: inode from wich the super block will be taken 1073ad20fe3SChristian Brauner * @userp: buffer to copy information about new device for userspace to 1083ad20fe3SChristian Brauner * @req: struct binderfs_device as copied from userspace 1093ad20fe3SChristian Brauner * 11001b3f1fcSChristian Brauner * This function allocates a new binder_device and reserves a new minor 1113ad20fe3SChristian Brauner * number for it. 1123ad20fe3SChristian Brauner * Minor numbers are limited and tracked globally in binderfs_minors. The 1133ad20fe3SChristian Brauner * function will stash a struct binder_device for the specific binder 1143ad20fe3SChristian Brauner * device in i_private of the inode. 1153ad20fe3SChristian Brauner * It will go on to allocate a new inode from the super block of the 1163ad20fe3SChristian Brauner * filesystem mount, stash a struct binder_device in its i_private field 1173ad20fe3SChristian Brauner * and attach a dentry to that inode. 1183ad20fe3SChristian Brauner * 1193ad20fe3SChristian Brauner * Return: 0 on success, negative errno on failure 1203ad20fe3SChristian Brauner */ 1213ad20fe3SChristian Brauner static int binderfs_binder_device_create(struct inode *ref_inode, 1223ad20fe3SChristian Brauner struct binderfs_device __user *userp, 1233ad20fe3SChristian Brauner struct binderfs_device *req) 1243ad20fe3SChristian Brauner { 1253ad20fe3SChristian Brauner int minor, ret; 12601b3f1fcSChristian Brauner struct dentry *dentry, *root; 1273ad20fe3SChristian Brauner struct binder_device *device; 1283ad20fe3SChristian Brauner char *name = NULL; 12901b3f1fcSChristian Brauner size_t name_len; 1303ad20fe3SChristian Brauner struct inode *inode = NULL; 1313ad20fe3SChristian Brauner struct super_block *sb = ref_inode->i_sb; 1323ad20fe3SChristian Brauner struct binderfs_info *info = sb->s_fs_info; 1337fefaaddSChristian Brauner #if defined(CONFIG_IPC_NS) 13436bdf3caSChristian Brauner bool use_reserve = (info->ipc_ns == &init_ipc_ns); 1357fefaaddSChristian Brauner #else 1367fefaaddSChristian Brauner bool use_reserve = true; 1377fefaaddSChristian Brauner #endif 1383ad20fe3SChristian Brauner 1393ad20fe3SChristian Brauner /* Reserve new minor number for the new device. */ 1403ad20fe3SChristian Brauner mutex_lock(&binderfs_minors_mutex); 141849d540dSChristian Brauner if (++info->device_count <= info->mount_opts.max) 14236bdf3caSChristian Brauner minor = ida_alloc_max(&binderfs_minors, 14336bdf3caSChristian Brauner use_reserve ? BINDERFS_MAX_MINOR : 14436bdf3caSChristian Brauner BINDERFS_MAX_MINOR_CAPPED, 145849d540dSChristian Brauner GFP_KERNEL); 146849d540dSChristian Brauner else 147849d540dSChristian Brauner minor = -ENOSPC; 148849d540dSChristian Brauner if (minor < 0) { 149849d540dSChristian Brauner --info->device_count; 1503ad20fe3SChristian Brauner mutex_unlock(&binderfs_minors_mutex); 1513ad20fe3SChristian Brauner return minor; 152849d540dSChristian Brauner } 153849d540dSChristian Brauner mutex_unlock(&binderfs_minors_mutex); 1543ad20fe3SChristian Brauner 1553ad20fe3SChristian Brauner ret = -ENOMEM; 1563ad20fe3SChristian Brauner device = kzalloc(sizeof(*device), GFP_KERNEL); 1573ad20fe3SChristian Brauner if (!device) 1583ad20fe3SChristian Brauner goto err; 1593ad20fe3SChristian Brauner 1603ad20fe3SChristian Brauner inode = new_inode(sb); 1613ad20fe3SChristian Brauner if (!inode) 1623ad20fe3SChristian Brauner goto err; 1633ad20fe3SChristian Brauner 1643ad20fe3SChristian Brauner inode->i_ino = minor + INODE_OFFSET; 1653ad20fe3SChristian Brauner inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 1663ad20fe3SChristian Brauner init_special_inode(inode, S_IFCHR | 0600, 1673ad20fe3SChristian Brauner MKDEV(MAJOR(binderfs_dev), minor)); 1683ad20fe3SChristian Brauner inode->i_fop = &binder_fops; 1693ad20fe3SChristian Brauner inode->i_uid = info->root_uid; 1703ad20fe3SChristian Brauner inode->i_gid = info->root_gid; 1713ad20fe3SChristian Brauner 17201b3f1fcSChristian Brauner req->name[BINDERFS_MAX_NAME] = '\0'; /* NUL-terminate */ 17301b3f1fcSChristian Brauner name_len = strlen(req->name); 17401b3f1fcSChristian Brauner /* Make sure to include terminating NUL byte */ 17501b3f1fcSChristian Brauner name = kmemdup(req->name, name_len + 1, GFP_KERNEL); 1763ad20fe3SChristian Brauner if (!name) 1773ad20fe3SChristian Brauner goto err; 1783ad20fe3SChristian Brauner 1793ad20fe3SChristian Brauner device->binderfs_inode = inode; 1803ad20fe3SChristian Brauner device->context.binder_context_mgr_uid = INVALID_UID; 1813ad20fe3SChristian Brauner device->context.name = name; 1823ad20fe3SChristian Brauner device->miscdev.name = name; 1833ad20fe3SChristian Brauner device->miscdev.minor = minor; 1843ad20fe3SChristian Brauner mutex_init(&device->context.context_mgr_node_lock); 1853ad20fe3SChristian Brauner 1863ad20fe3SChristian Brauner req->major = MAJOR(binderfs_dev); 1873ad20fe3SChristian Brauner req->minor = minor; 1883ad20fe3SChristian Brauner 189ca2864c6SHridya Valsaraju if (userp && copy_to_user(userp, req, sizeof(*req))) { 1903ad20fe3SChristian Brauner ret = -EFAULT; 1913ad20fe3SChristian Brauner goto err; 1923ad20fe3SChristian Brauner } 1933ad20fe3SChristian Brauner 1943ad20fe3SChristian Brauner root = sb->s_root; 1953ad20fe3SChristian Brauner inode_lock(d_inode(root)); 19601b3f1fcSChristian Brauner 19701b3f1fcSChristian Brauner /* look it up */ 19801b3f1fcSChristian Brauner dentry = lookup_one_len(name, root, name_len); 19901b3f1fcSChristian Brauner if (IS_ERR(dentry)) { 2003ad20fe3SChristian Brauner inode_unlock(d_inode(root)); 20101b3f1fcSChristian Brauner ret = PTR_ERR(dentry); 2023ad20fe3SChristian Brauner goto err; 2033ad20fe3SChristian Brauner } 2043ad20fe3SChristian Brauner 20501b3f1fcSChristian Brauner if (d_really_is_positive(dentry)) { 20601b3f1fcSChristian Brauner /* already exists */ 2073ad20fe3SChristian Brauner dput(dentry); 2083ad20fe3SChristian Brauner inode_unlock(d_inode(root)); 2093ad20fe3SChristian Brauner ret = -EEXIST; 2103ad20fe3SChristian Brauner goto err; 2113ad20fe3SChristian Brauner } 2123ad20fe3SChristian Brauner 2133ad20fe3SChristian Brauner inode->i_private = device; 21401684db9SChristian Brauner d_instantiate(dentry, inode); 2153ad20fe3SChristian Brauner fsnotify_create(root->d_inode, dentry); 2163ad20fe3SChristian Brauner inode_unlock(d_inode(root)); 2173ad20fe3SChristian Brauner 2183ad20fe3SChristian Brauner return 0; 2193ad20fe3SChristian Brauner 2203ad20fe3SChristian Brauner err: 2213ad20fe3SChristian Brauner kfree(name); 2223ad20fe3SChristian Brauner kfree(device); 2233ad20fe3SChristian Brauner mutex_lock(&binderfs_minors_mutex); 224849d540dSChristian Brauner --info->device_count; 2253ad20fe3SChristian Brauner ida_free(&binderfs_minors, minor); 2263ad20fe3SChristian Brauner mutex_unlock(&binderfs_minors_mutex); 2273ad20fe3SChristian Brauner iput(inode); 2283ad20fe3SChristian Brauner 2293ad20fe3SChristian Brauner return ret; 2303ad20fe3SChristian Brauner } 2313ad20fe3SChristian Brauner 2323ad20fe3SChristian Brauner /** 2333ad20fe3SChristian Brauner * binderfs_ctl_ioctl - handle binder device node allocation requests 2343ad20fe3SChristian Brauner * 2353ad20fe3SChristian Brauner * The request handler for the binder-control device. All requests operate on 2363ad20fe3SChristian Brauner * the binderfs mount the binder-control device resides in: 2373ad20fe3SChristian Brauner * - BINDER_CTL_ADD 2383ad20fe3SChristian Brauner * Allocate a new binder device. 2393ad20fe3SChristian Brauner * 2403ad20fe3SChristian Brauner * Return: 0 on success, negative errno on failure 2413ad20fe3SChristian Brauner */ 2423ad20fe3SChristian Brauner static long binder_ctl_ioctl(struct file *file, unsigned int cmd, 2433ad20fe3SChristian Brauner unsigned long arg) 2443ad20fe3SChristian Brauner { 2453ad20fe3SChristian Brauner int ret = -EINVAL; 2463ad20fe3SChristian Brauner struct inode *inode = file_inode(file); 2473ad20fe3SChristian Brauner struct binderfs_device __user *device = (struct binderfs_device __user *)arg; 2483ad20fe3SChristian Brauner struct binderfs_device device_req; 2493ad20fe3SChristian Brauner 2503ad20fe3SChristian Brauner switch (cmd) { 2513ad20fe3SChristian Brauner case BINDER_CTL_ADD: 2523ad20fe3SChristian Brauner ret = copy_from_user(&device_req, device, sizeof(device_req)); 2533ad20fe3SChristian Brauner if (ret) { 2543ad20fe3SChristian Brauner ret = -EFAULT; 2553ad20fe3SChristian Brauner break; 2563ad20fe3SChristian Brauner } 2573ad20fe3SChristian Brauner 2583ad20fe3SChristian Brauner ret = binderfs_binder_device_create(inode, device, &device_req); 2593ad20fe3SChristian Brauner break; 2603ad20fe3SChristian Brauner default: 2613ad20fe3SChristian Brauner break; 2623ad20fe3SChristian Brauner } 2633ad20fe3SChristian Brauner 2643ad20fe3SChristian Brauner return ret; 2653ad20fe3SChristian Brauner } 2663ad20fe3SChristian Brauner 2673ad20fe3SChristian Brauner static void binderfs_evict_inode(struct inode *inode) 2683ad20fe3SChristian Brauner { 2693ad20fe3SChristian Brauner struct binder_device *device = inode->i_private; 270849d540dSChristian Brauner struct binderfs_info *info = BINDERFS_I(inode); 2713ad20fe3SChristian Brauner 2723ad20fe3SChristian Brauner clear_inode(inode); 2733ad20fe3SChristian Brauner 2743ad20fe3SChristian Brauner if (!device) 2753ad20fe3SChristian Brauner return; 2763ad20fe3SChristian Brauner 2773ad20fe3SChristian Brauner mutex_lock(&binderfs_minors_mutex); 278849d540dSChristian Brauner --info->device_count; 2793ad20fe3SChristian Brauner ida_free(&binderfs_minors, device->miscdev.minor); 2803ad20fe3SChristian Brauner mutex_unlock(&binderfs_minors_mutex); 2813ad20fe3SChristian Brauner 2823ad20fe3SChristian Brauner kfree(device->context.name); 2833ad20fe3SChristian Brauner kfree(device); 2843ad20fe3SChristian Brauner } 2853ad20fe3SChristian Brauner 286849d540dSChristian Brauner /** 287849d540dSChristian Brauner * binderfs_parse_mount_opts - parse binderfs mount options 288849d540dSChristian Brauner * @data: options to set (can be NULL in which case defaults are used) 289849d540dSChristian Brauner */ 290849d540dSChristian Brauner static int binderfs_parse_mount_opts(char *data, 291849d540dSChristian Brauner struct binderfs_mount_opts *opts) 292849d540dSChristian Brauner { 293849d540dSChristian Brauner char *p; 294849d540dSChristian Brauner opts->max = BINDERFS_MAX_MINOR; 295849d540dSChristian Brauner 296849d540dSChristian Brauner while ((p = strsep(&data, ",")) != NULL) { 297849d540dSChristian Brauner substring_t args[MAX_OPT_ARGS]; 298849d540dSChristian Brauner int token; 299849d540dSChristian Brauner int max_devices; 300849d540dSChristian Brauner 301849d540dSChristian Brauner if (!*p) 302849d540dSChristian Brauner continue; 303849d540dSChristian Brauner 304849d540dSChristian Brauner token = match_token(p, tokens, args); 305849d540dSChristian Brauner switch (token) { 306849d540dSChristian Brauner case Opt_max: 307849d540dSChristian Brauner if (match_int(&args[0], &max_devices) || 308849d540dSChristian Brauner (max_devices < 0 || 309849d540dSChristian Brauner (max_devices > BINDERFS_MAX_MINOR))) 310849d540dSChristian Brauner return -EINVAL; 311849d540dSChristian Brauner 312849d540dSChristian Brauner opts->max = max_devices; 313849d540dSChristian Brauner break; 314849d540dSChristian Brauner default: 315849d540dSChristian Brauner pr_err("Invalid mount options\n"); 316849d540dSChristian Brauner return -EINVAL; 317849d540dSChristian Brauner } 318849d540dSChristian Brauner } 319849d540dSChristian Brauner 320849d540dSChristian Brauner return 0; 321849d540dSChristian Brauner } 322849d540dSChristian Brauner 323849d540dSChristian Brauner static int binderfs_remount(struct super_block *sb, int *flags, char *data) 324849d540dSChristian Brauner { 325849d540dSChristian Brauner struct binderfs_info *info = sb->s_fs_info; 326849d540dSChristian Brauner return binderfs_parse_mount_opts(data, &info->mount_opts); 327849d540dSChristian Brauner } 328849d540dSChristian Brauner 329849d540dSChristian Brauner static int binderfs_show_mount_opts(struct seq_file *seq, struct dentry *root) 330849d540dSChristian Brauner { 331849d540dSChristian Brauner struct binderfs_info *info; 332849d540dSChristian Brauner 333849d540dSChristian Brauner info = root->d_sb->s_fs_info; 334849d540dSChristian Brauner if (info->mount_opts.max <= BINDERFS_MAX_MINOR) 335849d540dSChristian Brauner seq_printf(seq, ",max=%d", info->mount_opts.max); 336849d540dSChristian Brauner 337849d540dSChristian Brauner return 0; 338849d540dSChristian Brauner } 339849d540dSChristian Brauner 3403ad20fe3SChristian Brauner static const struct super_operations binderfs_super_ops = { 3413ad20fe3SChristian Brauner .evict_inode = binderfs_evict_inode, 342849d540dSChristian Brauner .remount_fs = binderfs_remount, 343849d540dSChristian Brauner .show_options = binderfs_show_mount_opts, 344849d540dSChristian Brauner .statfs = simple_statfs, 3453ad20fe3SChristian Brauner }; 3463ad20fe3SChristian Brauner 347e98e6fa1SChristian Brauner static inline bool is_binderfs_control_device(const struct dentry *dentry) 348e98e6fa1SChristian Brauner { 349e98e6fa1SChristian Brauner struct binderfs_info *info = dentry->d_sb->s_fs_info; 350e98e6fa1SChristian Brauner return info->control_dentry == dentry; 351e98e6fa1SChristian Brauner } 352e98e6fa1SChristian Brauner 3533ad20fe3SChristian Brauner static int binderfs_rename(struct inode *old_dir, struct dentry *old_dentry, 3543ad20fe3SChristian Brauner struct inode *new_dir, struct dentry *new_dentry, 3553ad20fe3SChristian Brauner unsigned int flags) 3563ad20fe3SChristian Brauner { 357e98e6fa1SChristian Brauner if (is_binderfs_control_device(old_dentry) || 358e98e6fa1SChristian Brauner is_binderfs_control_device(new_dentry)) 3593ad20fe3SChristian Brauner return -EPERM; 3603ad20fe3SChristian Brauner 361e98e6fa1SChristian Brauner return simple_rename(old_dir, old_dentry, new_dir, new_dentry, flags); 3623ad20fe3SChristian Brauner } 3633ad20fe3SChristian Brauner 3643ad20fe3SChristian Brauner static int binderfs_unlink(struct inode *dir, struct dentry *dentry) 3653ad20fe3SChristian Brauner { 366e98e6fa1SChristian Brauner if (is_binderfs_control_device(dentry)) 3673ad20fe3SChristian Brauner return -EPERM; 3683ad20fe3SChristian Brauner 3693ad20fe3SChristian Brauner return simple_unlink(dir, dentry); 3703ad20fe3SChristian Brauner } 3713ad20fe3SChristian Brauner 3723ad20fe3SChristian Brauner static const struct file_operations binder_ctl_fops = { 3733ad20fe3SChristian Brauner .owner = THIS_MODULE, 3743ad20fe3SChristian Brauner .open = nonseekable_open, 3753ad20fe3SChristian Brauner .unlocked_ioctl = binder_ctl_ioctl, 3763ad20fe3SChristian Brauner .compat_ioctl = binder_ctl_ioctl, 3773ad20fe3SChristian Brauner .llseek = noop_llseek, 3783ad20fe3SChristian Brauner }; 3793ad20fe3SChristian Brauner 3803ad20fe3SChristian Brauner /** 3813ad20fe3SChristian Brauner * binderfs_binder_ctl_create - create a new binder-control device 3823ad20fe3SChristian Brauner * @sb: super block of the binderfs mount 3833ad20fe3SChristian Brauner * 3843ad20fe3SChristian Brauner * This function creates a new binder-control device node in the binderfs mount 3853ad20fe3SChristian Brauner * referred to by @sb. 3863ad20fe3SChristian Brauner * 3873ad20fe3SChristian Brauner * Return: 0 on success, negative errno on failure 3883ad20fe3SChristian Brauner */ 3893ad20fe3SChristian Brauner static int binderfs_binder_ctl_create(struct super_block *sb) 3903ad20fe3SChristian Brauner { 3913ad20fe3SChristian Brauner int minor, ret; 3923ad20fe3SChristian Brauner struct dentry *dentry; 3933ad20fe3SChristian Brauner struct binder_device *device; 3943ad20fe3SChristian Brauner struct inode *inode = NULL; 3953ad20fe3SChristian Brauner struct dentry *root = sb->s_root; 3963ad20fe3SChristian Brauner struct binderfs_info *info = sb->s_fs_info; 397da8ddba5SChristian Brauner #if defined(CONFIG_IPC_NS) 398da8ddba5SChristian Brauner bool use_reserve = (info->ipc_ns == &init_ipc_ns); 399da8ddba5SChristian Brauner #else 400da8ddba5SChristian Brauner bool use_reserve = true; 401da8ddba5SChristian Brauner #endif 4023ad20fe3SChristian Brauner 4033ad20fe3SChristian Brauner device = kzalloc(sizeof(*device), GFP_KERNEL); 4043ad20fe3SChristian Brauner if (!device) 4053ad20fe3SChristian Brauner return -ENOMEM; 4063ad20fe3SChristian Brauner 4073ad20fe3SChristian Brauner /* If we have already created a binder-control node, return. */ 4083ad20fe3SChristian Brauner if (info->control_dentry) { 4093ad20fe3SChristian Brauner ret = 0; 4103ad20fe3SChristian Brauner goto out; 4113ad20fe3SChristian Brauner } 4123ad20fe3SChristian Brauner 4133ad20fe3SChristian Brauner ret = -ENOMEM; 4143ad20fe3SChristian Brauner inode = new_inode(sb); 4153ad20fe3SChristian Brauner if (!inode) 4163ad20fe3SChristian Brauner goto out; 4173ad20fe3SChristian Brauner 4183ad20fe3SChristian Brauner /* Reserve a new minor number for the new device. */ 4193ad20fe3SChristian Brauner mutex_lock(&binderfs_minors_mutex); 420da8ddba5SChristian Brauner minor = ida_alloc_max(&binderfs_minors, 421da8ddba5SChristian Brauner use_reserve ? BINDERFS_MAX_MINOR : 422da8ddba5SChristian Brauner BINDERFS_MAX_MINOR_CAPPED, 423da8ddba5SChristian Brauner GFP_KERNEL); 4243ad20fe3SChristian Brauner mutex_unlock(&binderfs_minors_mutex); 4253ad20fe3SChristian Brauner if (minor < 0) { 4263ad20fe3SChristian Brauner ret = minor; 4273ad20fe3SChristian Brauner goto out; 4283ad20fe3SChristian Brauner } 4293ad20fe3SChristian Brauner 4303ad20fe3SChristian Brauner inode->i_ino = SECOND_INODE; 4313ad20fe3SChristian Brauner inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 4323ad20fe3SChristian Brauner init_special_inode(inode, S_IFCHR | 0600, 4333ad20fe3SChristian Brauner MKDEV(MAJOR(binderfs_dev), minor)); 4343ad20fe3SChristian Brauner inode->i_fop = &binder_ctl_fops; 4353ad20fe3SChristian Brauner inode->i_uid = info->root_uid; 4363ad20fe3SChristian Brauner inode->i_gid = info->root_gid; 4373ad20fe3SChristian Brauner 4383ad20fe3SChristian Brauner device->binderfs_inode = inode; 4393ad20fe3SChristian Brauner device->miscdev.minor = minor; 4403ad20fe3SChristian Brauner 4413ad20fe3SChristian Brauner dentry = d_alloc_name(root, "binder-control"); 4423ad20fe3SChristian Brauner if (!dentry) 4433ad20fe3SChristian Brauner goto out; 4443ad20fe3SChristian Brauner 4453ad20fe3SChristian Brauner inode->i_private = device; 4463ad20fe3SChristian Brauner info->control_dentry = dentry; 4473ad20fe3SChristian Brauner d_add(dentry, inode); 4483ad20fe3SChristian Brauner 4493ad20fe3SChristian Brauner return 0; 4503ad20fe3SChristian Brauner 4513ad20fe3SChristian Brauner out: 4523ad20fe3SChristian Brauner kfree(device); 4533ad20fe3SChristian Brauner iput(inode); 4543ad20fe3SChristian Brauner 4553ad20fe3SChristian Brauner return ret; 4563ad20fe3SChristian Brauner } 4573ad20fe3SChristian Brauner 4583ad20fe3SChristian Brauner static const struct inode_operations binderfs_dir_inode_operations = { 4593ad20fe3SChristian Brauner .lookup = simple_lookup, 4603ad20fe3SChristian Brauner .rename = binderfs_rename, 4613ad20fe3SChristian Brauner .unlink = binderfs_unlink, 4623ad20fe3SChristian Brauner }; 4633ad20fe3SChristian Brauner 4643ad20fe3SChristian Brauner static int binderfs_fill_super(struct super_block *sb, void *data, int silent) 4653ad20fe3SChristian Brauner { 46636975fc3SChristian Brauner int ret; 4673ad20fe3SChristian Brauner struct binderfs_info *info; 4683ad20fe3SChristian Brauner struct inode *inode = NULL; 469ca2864c6SHridya Valsaraju struct binderfs_device device_info = { 0 }; 470ca2864c6SHridya Valsaraju const char *name; 471ca2864c6SHridya Valsaraju size_t len; 4723ad20fe3SChristian Brauner 4733ad20fe3SChristian Brauner sb->s_blocksize = PAGE_SIZE; 4743ad20fe3SChristian Brauner sb->s_blocksize_bits = PAGE_SHIFT; 4753ad20fe3SChristian Brauner 4763ad20fe3SChristian Brauner /* 4773ad20fe3SChristian Brauner * The binderfs filesystem can be mounted by userns root in a 4783ad20fe3SChristian Brauner * non-initial userns. By default such mounts have the SB_I_NODEV flag 4793ad20fe3SChristian Brauner * set in s_iflags to prevent security issues where userns root can 4803ad20fe3SChristian Brauner * just create random device nodes via mknod() since it owns the 4813ad20fe3SChristian Brauner * filesystem mount. But binderfs does not allow to create any files 4823ad20fe3SChristian Brauner * including devices nodes. The only way to create binder devices nodes 4833ad20fe3SChristian Brauner * is through the binder-control device which userns root is explicitly 4843ad20fe3SChristian Brauner * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both 4853ad20fe3SChristian Brauner * necessary and safe. 4863ad20fe3SChristian Brauner */ 4873ad20fe3SChristian Brauner sb->s_iflags &= ~SB_I_NODEV; 4883ad20fe3SChristian Brauner sb->s_iflags |= SB_I_NOEXEC; 4893ad20fe3SChristian Brauner sb->s_magic = BINDERFS_SUPER_MAGIC; 4903ad20fe3SChristian Brauner sb->s_op = &binderfs_super_ops; 4913ad20fe3SChristian Brauner sb->s_time_gran = 1; 4923ad20fe3SChristian Brauner 49336975fc3SChristian Brauner sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL); 49436975fc3SChristian Brauner if (!sb->s_fs_info) 49536975fc3SChristian Brauner return -ENOMEM; 49636975fc3SChristian Brauner info = sb->s_fs_info; 49736975fc3SChristian Brauner 49836975fc3SChristian Brauner info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns); 4993ad20fe3SChristian Brauner 500849d540dSChristian Brauner ret = binderfs_parse_mount_opts(data, &info->mount_opts); 501849d540dSChristian Brauner if (ret) 50236975fc3SChristian Brauner return ret; 503849d540dSChristian Brauner 5043ad20fe3SChristian Brauner info->root_gid = make_kgid(sb->s_user_ns, 0); 5053ad20fe3SChristian Brauner if (!gid_valid(info->root_gid)) 5063ad20fe3SChristian Brauner info->root_gid = GLOBAL_ROOT_GID; 5073ad20fe3SChristian Brauner info->root_uid = make_kuid(sb->s_user_ns, 0); 5083ad20fe3SChristian Brauner if (!uid_valid(info->root_uid)) 5093ad20fe3SChristian Brauner info->root_uid = GLOBAL_ROOT_UID; 5103ad20fe3SChristian Brauner 5113ad20fe3SChristian Brauner inode = new_inode(sb); 5123ad20fe3SChristian Brauner if (!inode) 51336975fc3SChristian Brauner return -ENOMEM; 5143ad20fe3SChristian Brauner 5153ad20fe3SChristian Brauner inode->i_ino = FIRST_INODE; 5163ad20fe3SChristian Brauner inode->i_fop = &simple_dir_operations; 5173ad20fe3SChristian Brauner inode->i_mode = S_IFDIR | 0755; 5183ad20fe3SChristian Brauner inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 5193ad20fe3SChristian Brauner inode->i_op = &binderfs_dir_inode_operations; 5203ad20fe3SChristian Brauner set_nlink(inode, 2); 5213ad20fe3SChristian Brauner 5223ad20fe3SChristian Brauner sb->s_root = d_make_root(inode); 5233ad20fe3SChristian Brauner if (!sb->s_root) 52436975fc3SChristian Brauner return -ENOMEM; 5253ad20fe3SChristian Brauner 526ca2864c6SHridya Valsaraju ret = binderfs_binder_ctl_create(sb); 527ca2864c6SHridya Valsaraju if (ret) 528ca2864c6SHridya Valsaraju return ret; 529ca2864c6SHridya Valsaraju 530ca2864c6SHridya Valsaraju name = binder_devices_param; 531ca2864c6SHridya Valsaraju for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) { 532ca2864c6SHridya Valsaraju strscpy(device_info.name, name, len + 1); 533ca2864c6SHridya Valsaraju ret = binderfs_binder_device_create(inode, NULL, &device_info); 534ca2864c6SHridya Valsaraju if (ret) 535ca2864c6SHridya Valsaraju return ret; 536ca2864c6SHridya Valsaraju name += len; 537ca2864c6SHridya Valsaraju if (*name == ',') 538ca2864c6SHridya Valsaraju name++; 539ca2864c6SHridya Valsaraju } 540ca2864c6SHridya Valsaraju 541ca2864c6SHridya Valsaraju return 0; 5423ad20fe3SChristian Brauner } 5433ad20fe3SChristian Brauner 5443ad20fe3SChristian Brauner static struct dentry *binderfs_mount(struct file_system_type *fs_type, 5453ad20fe3SChristian Brauner int flags, const char *dev_name, 5463ad20fe3SChristian Brauner void *data) 5473ad20fe3SChristian Brauner { 548b6c770d7SChristian Brauner return mount_nodev(fs_type, flags, data, binderfs_fill_super); 5493ad20fe3SChristian Brauner } 5503ad20fe3SChristian Brauner 5513ad20fe3SChristian Brauner static void binderfs_kill_super(struct super_block *sb) 5523ad20fe3SChristian Brauner { 5533ad20fe3SChristian Brauner struct binderfs_info *info = sb->s_fs_info; 5543ad20fe3SChristian Brauner 55541984795SChristian Brauner kill_litter_super(sb); 55641984795SChristian Brauner 5573ad20fe3SChristian Brauner if (info && info->ipc_ns) 5583ad20fe3SChristian Brauner put_ipc_ns(info->ipc_ns); 5593ad20fe3SChristian Brauner 5603ad20fe3SChristian Brauner kfree(info); 5613ad20fe3SChristian Brauner } 5623ad20fe3SChristian Brauner 5633ad20fe3SChristian Brauner static struct file_system_type binder_fs_type = { 5643ad20fe3SChristian Brauner .name = "binder", 5653ad20fe3SChristian Brauner .mount = binderfs_mount, 5663ad20fe3SChristian Brauner .kill_sb = binderfs_kill_super, 5673ad20fe3SChristian Brauner .fs_flags = FS_USERNS_MOUNT, 5683ad20fe3SChristian Brauner }; 5693ad20fe3SChristian Brauner 5705b9633afSChristian Brauner int __init init_binderfs(void) 5713ad20fe3SChristian Brauner { 5723ad20fe3SChristian Brauner int ret; 573028fb582SHridya Valsaraju const char *name; 574028fb582SHridya Valsaraju size_t len; 575028fb582SHridya Valsaraju 576028fb582SHridya Valsaraju /* Verify that the default binderfs device names are valid. */ 577028fb582SHridya Valsaraju name = binder_devices_param; 578028fb582SHridya Valsaraju for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) { 579028fb582SHridya Valsaraju if (len > BINDERFS_MAX_NAME) 580028fb582SHridya Valsaraju return -E2BIG; 581028fb582SHridya Valsaraju name += len; 582028fb582SHridya Valsaraju if (*name == ',') 583028fb582SHridya Valsaraju name++; 584028fb582SHridya Valsaraju } 5853ad20fe3SChristian Brauner 5863ad20fe3SChristian Brauner /* Allocate new major number for binderfs. */ 5873ad20fe3SChristian Brauner ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR, 5883ad20fe3SChristian Brauner "binder"); 5893ad20fe3SChristian Brauner if (ret) 5903ad20fe3SChristian Brauner return ret; 5913ad20fe3SChristian Brauner 5923ad20fe3SChristian Brauner ret = register_filesystem(&binder_fs_type); 5933ad20fe3SChristian Brauner if (ret) { 5943ad20fe3SChristian Brauner unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR); 5953ad20fe3SChristian Brauner return ret; 5963ad20fe3SChristian Brauner } 5973ad20fe3SChristian Brauner 5983ad20fe3SChristian Brauner return ret; 5993ad20fe3SChristian Brauner } 600