1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0
2e149ed2bSAl Viro #include <linux/mount.h>
3059b20d9SDavid Howells #include <linux/pseudo_fs.h>
4e149ed2bSAl Viro #include <linux/file.h>
5e149ed2bSAl Viro #include <linux/fs.h>
67bebd69eSEric Biggers #include <linux/proc_fs.h>
7e149ed2bSAl Viro #include <linux/proc_ns.h>
8e149ed2bSAl Viro #include <linux/magic.h>
9e149ed2bSAl Viro #include <linux/ktime.h>
1075509fd8SEric W. Biederman #include <linux/seq_file.h>
116786741dSAndrey Vagin #include <linux/user_namespace.h>
126786741dSAndrey Vagin #include <linux/nsfs.h>
13d95fa3c7SMichael Kerrisk (man-pages) #include <linux/uaccess.h>
14e149ed2bSAl Viro
157bebd69eSEric Biggers #include "internal.h"
167bebd69eSEric Biggers
17e149ed2bSAl Viro static struct vfsmount *nsfs_mnt;
18e149ed2bSAl Viro
196786741dSAndrey Vagin static long ns_ioctl(struct file *filp, unsigned int ioctl,
206786741dSAndrey Vagin unsigned long arg);
21e149ed2bSAl Viro static const struct file_operations ns_file_operations = {
22e149ed2bSAl Viro .llseek = no_llseek,
236786741dSAndrey Vagin .unlocked_ioctl = ns_ioctl,
241cb925c0SThomas Weißschuh .compat_ioctl = compat_ptr_ioctl,
25e149ed2bSAl Viro };
26e149ed2bSAl Viro
ns_dname(struct dentry * dentry,char * buffer,int buflen)27e149ed2bSAl Viro static char *ns_dname(struct dentry *dentry, char *buffer, int buflen)
28e149ed2bSAl Viro {
2975c3cfa8SDavid Howells struct inode *inode = d_inode(dentry);
30e149ed2bSAl Viro const struct proc_ns_operations *ns_ops = dentry->d_fsdata;
31e149ed2bSAl Viro
320f60d288SAl Viro return dynamic_dname(buffer, buflen, "%s:[%lu]",
33e149ed2bSAl Viro ns_ops->name, inode->i_ino);
34e149ed2bSAl Viro }
35e149ed2bSAl Viro
ns_prune_dentry(struct dentry * dentry)36e149ed2bSAl Viro static void ns_prune_dentry(struct dentry *dentry)
37e149ed2bSAl Viro {
3875c3cfa8SDavid Howells struct inode *inode = d_inode(dentry);
39e149ed2bSAl Viro if (inode) {
40e149ed2bSAl Viro struct ns_common *ns = inode->i_private;
41e149ed2bSAl Viro atomic_long_set(&ns->stashed, 0);
42e149ed2bSAl Viro }
43e149ed2bSAl Viro }
44e149ed2bSAl Viro
45e149ed2bSAl Viro const struct dentry_operations ns_dentry_operations =
46e149ed2bSAl Viro {
47e149ed2bSAl Viro .d_prune = ns_prune_dentry,
48e149ed2bSAl Viro .d_delete = always_delete_dentry,
49e149ed2bSAl Viro .d_dname = ns_dname,
50e149ed2bSAl Viro };
51e149ed2bSAl Viro
nsfs_evict(struct inode * inode)52e149ed2bSAl Viro static void nsfs_evict(struct inode *inode)
53e149ed2bSAl Viro {
54e149ed2bSAl Viro struct ns_common *ns = inode->i_private;
55e149ed2bSAl Viro clear_inode(inode);
56e149ed2bSAl Viro ns->ops->put(ns);
57e149ed2bSAl Viro }
58e149ed2bSAl Viro
__ns_get_path(struct path * path,struct ns_common * ns)59ce623f89SAleksa Sarai static int __ns_get_path(struct path *path, struct ns_common *ns)
60e149ed2bSAl Viro {
61213b067cSEric W. Biederman struct vfsmount *mnt = nsfs_mnt;
62e149ed2bSAl Viro struct dentry *dentry;
63e149ed2bSAl Viro struct inode *inode;
64e149ed2bSAl Viro unsigned long d;
65e149ed2bSAl Viro
66e149ed2bSAl Viro rcu_read_lock();
67e149ed2bSAl Viro d = atomic_long_read(&ns->stashed);
68e149ed2bSAl Viro if (!d)
69e149ed2bSAl Viro goto slow;
70e149ed2bSAl Viro dentry = (struct dentry *)d;
71e149ed2bSAl Viro if (!lockref_get_not_dead(&dentry->d_lockref))
72e149ed2bSAl Viro goto slow;
73e149ed2bSAl Viro rcu_read_unlock();
746786741dSAndrey Vagin ns->ops->put(ns);
75e149ed2bSAl Viro got_it:
76213b067cSEric W. Biederman path->mnt = mntget(mnt);
77e149ed2bSAl Viro path->dentry = dentry;
78ce623f89SAleksa Sarai return 0;
79e149ed2bSAl Viro slow:
80e149ed2bSAl Viro rcu_read_unlock();
81e149ed2bSAl Viro inode = new_inode_pseudo(mnt->mnt_sb);
82e149ed2bSAl Viro if (!inode) {
836786741dSAndrey Vagin ns->ops->put(ns);
84ce623f89SAleksa Sarai return -ENOMEM;
85e149ed2bSAl Viro }
86e149ed2bSAl Viro inode->i_ino = ns->inum;
87*2276e5baSJeff Layton inode->i_mtime = inode->i_atime = inode_set_ctime_current(inode);
88e149ed2bSAl Viro inode->i_flags |= S_IMMUTABLE;
89e149ed2bSAl Viro inode->i_mode = S_IFREG | S_IRUGO;
90e149ed2bSAl Viro inode->i_fop = &ns_file_operations;
91e149ed2bSAl Viro inode->i_private = ns;
92e149ed2bSAl Viro
935467a68cSAl Viro dentry = d_alloc_anon(mnt->mnt_sb);
94e149ed2bSAl Viro if (!dentry) {
95e149ed2bSAl Viro iput(inode);
96ce623f89SAleksa Sarai return -ENOMEM;
97e149ed2bSAl Viro }
98e149ed2bSAl Viro d_instantiate(dentry, inode);
996786741dSAndrey Vagin dentry->d_fsdata = (void *)ns->ops;
100e149ed2bSAl Viro d = atomic_long_cmpxchg(&ns->stashed, 0, (unsigned long)dentry);
101e149ed2bSAl Viro if (d) {
102e149ed2bSAl Viro d_delete(dentry); /* make sure ->d_prune() does nothing */
103e149ed2bSAl Viro dput(dentry);
104e149ed2bSAl Viro cpu_relax();
105ce623f89SAleksa Sarai return -EAGAIN;
106e149ed2bSAl Viro }
107e149ed2bSAl Viro goto got_it;
108e149ed2bSAl Viro }
109e149ed2bSAl Viro
ns_get_path_cb(struct path * path,ns_get_path_helper_t * ns_get_cb,void * private_data)110ce623f89SAleksa Sarai int ns_get_path_cb(struct path *path, ns_get_path_helper_t *ns_get_cb,
111cdab6ba8SJakub Kicinski void *private_data)
1126786741dSAndrey Vagin {
113ce623f89SAleksa Sarai int ret;
1146786741dSAndrey Vagin
115357ab5b5SAl Viro do {
116357ab5b5SAl Viro struct ns_common *ns = ns_get_cb(private_data);
1176786741dSAndrey Vagin if (!ns)
118ce623f89SAleksa Sarai return -ENOENT;
1196786741dSAndrey Vagin ret = __ns_get_path(path, ns);
120ce623f89SAleksa Sarai } while (ret == -EAGAIN);
121357ab5b5SAl Viro
1226786741dSAndrey Vagin return ret;
1236786741dSAndrey Vagin }
1246786741dSAndrey Vagin
125cdab6ba8SJakub Kicinski struct ns_get_path_task_args {
126cdab6ba8SJakub Kicinski const struct proc_ns_operations *ns_ops;
127cdab6ba8SJakub Kicinski struct task_struct *task;
128cdab6ba8SJakub Kicinski };
129cdab6ba8SJakub Kicinski
ns_get_path_task(void * private_data)130cdab6ba8SJakub Kicinski static struct ns_common *ns_get_path_task(void *private_data)
131cdab6ba8SJakub Kicinski {
132cdab6ba8SJakub Kicinski struct ns_get_path_task_args *args = private_data;
133cdab6ba8SJakub Kicinski
134cdab6ba8SJakub Kicinski return args->ns_ops->get(args->task);
135cdab6ba8SJakub Kicinski }
136cdab6ba8SJakub Kicinski
ns_get_path(struct path * path,struct task_struct * task,const struct proc_ns_operations * ns_ops)137ce623f89SAleksa Sarai int ns_get_path(struct path *path, struct task_struct *task,
138cdab6ba8SJakub Kicinski const struct proc_ns_operations *ns_ops)
139cdab6ba8SJakub Kicinski {
140cdab6ba8SJakub Kicinski struct ns_get_path_task_args args = {
141cdab6ba8SJakub Kicinski .ns_ops = ns_ops,
142cdab6ba8SJakub Kicinski .task = task,
143cdab6ba8SJakub Kicinski };
144cdab6ba8SJakub Kicinski
145cdab6ba8SJakub Kicinski return ns_get_path_cb(path, ns_get_path_task, &args);
146cdab6ba8SJakub Kicinski }
147cdab6ba8SJakub Kicinski
open_related_ns(struct ns_common * ns,struct ns_common * (* get_ns)(struct ns_common * ns))148c62cce2cSAndrey Vagin int open_related_ns(struct ns_common *ns,
1496786741dSAndrey Vagin struct ns_common *(*get_ns)(struct ns_common *ns))
1506786741dSAndrey Vagin {
1516786741dSAndrey Vagin struct path path = {};
1526786741dSAndrey Vagin struct file *f;
153ce623f89SAleksa Sarai int err;
1546786741dSAndrey Vagin int fd;
1556786741dSAndrey Vagin
1566786741dSAndrey Vagin fd = get_unused_fd_flags(O_CLOEXEC);
1576786741dSAndrey Vagin if (fd < 0)
1586786741dSAndrey Vagin return fd;
1596786741dSAndrey Vagin
160357ab5b5SAl Viro do {
1616786741dSAndrey Vagin struct ns_common *relative;
1626786741dSAndrey Vagin
1636786741dSAndrey Vagin relative = get_ns(ns);
1646786741dSAndrey Vagin if (IS_ERR(relative)) {
1656786741dSAndrey Vagin put_unused_fd(fd);
1666786741dSAndrey Vagin return PTR_ERR(relative);
1676786741dSAndrey Vagin }
1686786741dSAndrey Vagin
1696786741dSAndrey Vagin err = __ns_get_path(&path, relative);
170ce623f89SAleksa Sarai } while (err == -EAGAIN);
171357ab5b5SAl Viro
172ce623f89SAleksa Sarai if (err) {
1736786741dSAndrey Vagin put_unused_fd(fd);
174ce623f89SAleksa Sarai return err;
1756786741dSAndrey Vagin }
1766786741dSAndrey Vagin
1776786741dSAndrey Vagin f = dentry_open(&path, O_RDONLY, current_cred());
1786786741dSAndrey Vagin path_put(&path);
1796786741dSAndrey Vagin if (IS_ERR(f)) {
1806786741dSAndrey Vagin put_unused_fd(fd);
1816786741dSAndrey Vagin fd = PTR_ERR(f);
1826786741dSAndrey Vagin } else
1836786741dSAndrey Vagin fd_install(fd, f);
1846786741dSAndrey Vagin
1856786741dSAndrey Vagin return fd;
1866786741dSAndrey Vagin }
18724dce080SKirill Tkhai EXPORT_SYMBOL_GPL(open_related_ns);
1886786741dSAndrey Vagin
ns_ioctl(struct file * filp,unsigned int ioctl,unsigned long arg)1896786741dSAndrey Vagin static long ns_ioctl(struct file *filp, unsigned int ioctl,
1906786741dSAndrey Vagin unsigned long arg)
1916786741dSAndrey Vagin {
192d95fa3c7SMichael Kerrisk (man-pages) struct user_namespace *user_ns;
1936786741dSAndrey Vagin struct ns_common *ns = get_proc_ns(file_inode(filp));
194d95fa3c7SMichael Kerrisk (man-pages) uid_t __user *argp;
195d95fa3c7SMichael Kerrisk (man-pages) uid_t uid;
1966786741dSAndrey Vagin
1976786741dSAndrey Vagin switch (ioctl) {
1986786741dSAndrey Vagin case NS_GET_USERNS:
1996786741dSAndrey Vagin return open_related_ns(ns, ns_get_owner);
200a7306ed8SAndrey Vagin case NS_GET_PARENT:
201a7306ed8SAndrey Vagin if (!ns->ops->get_parent)
202a7306ed8SAndrey Vagin return -EINVAL;
203a7306ed8SAndrey Vagin return open_related_ns(ns, ns->ops->get_parent);
204e5ff5ce6SMichael Kerrisk (man-pages) case NS_GET_NSTYPE:
205e5ff5ce6SMichael Kerrisk (man-pages) return ns->ops->type;
206d95fa3c7SMichael Kerrisk (man-pages) case NS_GET_OWNER_UID:
207d95fa3c7SMichael Kerrisk (man-pages) if (ns->ops->type != CLONE_NEWUSER)
208d95fa3c7SMichael Kerrisk (man-pages) return -EINVAL;
209d95fa3c7SMichael Kerrisk (man-pages) user_ns = container_of(ns, struct user_namespace, ns);
210d95fa3c7SMichael Kerrisk (man-pages) argp = (uid_t __user *) arg;
211d95fa3c7SMichael Kerrisk (man-pages) uid = from_kuid_munged(current_user_ns(), user_ns->owner);
212d95fa3c7SMichael Kerrisk (man-pages) return put_user(uid, argp);
2136786741dSAndrey Vagin default:
2146786741dSAndrey Vagin return -ENOTTY;
2156786741dSAndrey Vagin }
2166786741dSAndrey Vagin }
2176786741dSAndrey Vagin
ns_get_name(char * buf,size_t size,struct task_struct * task,const struct proc_ns_operations * ns_ops)218e149ed2bSAl Viro int ns_get_name(char *buf, size_t size, struct task_struct *task,
219e149ed2bSAl Viro const struct proc_ns_operations *ns_ops)
220e149ed2bSAl Viro {
221e149ed2bSAl Viro struct ns_common *ns;
222e149ed2bSAl Viro int res = -ENOENT;
22325b14e92SKirill Tkhai const char *name;
224e149ed2bSAl Viro ns = ns_ops->get(task);
225e149ed2bSAl Viro if (ns) {
22625b14e92SKirill Tkhai name = ns_ops->real_ns_name ? : ns_ops->name;
22725b14e92SKirill Tkhai res = snprintf(buf, size, "%s:[%u]", name, ns->inum);
228e149ed2bSAl Viro ns_ops->put(ns);
229e149ed2bSAl Viro }
230e149ed2bSAl Viro return res;
231e149ed2bSAl Viro }
232e149ed2bSAl Viro
proc_ns_file(const struct file * file)233303cc571SChristian Brauner bool proc_ns_file(const struct file *file)
234303cc571SChristian Brauner {
235303cc571SChristian Brauner return file->f_op == &ns_file_operations;
236303cc571SChristian Brauner }
237303cc571SChristian Brauner
2381e2328e7SCarlos Neira /**
2391e2328e7SCarlos Neira * ns_match() - Returns true if current namespace matches dev/ino provided.
24039ecb653SLukas Bulwahn * @ns: current namespace
2411e2328e7SCarlos Neira * @dev: dev_t from nsfs that will be matched against current nsfs
2421e2328e7SCarlos Neira * @ino: ino_t from nsfs that will be matched against current nsfs
2431e2328e7SCarlos Neira *
2441e2328e7SCarlos Neira * Return: true if dev and ino matches the current nsfs.
2451e2328e7SCarlos Neira */
ns_match(const struct ns_common * ns,dev_t dev,ino_t ino)2461e2328e7SCarlos Neira bool ns_match(const struct ns_common *ns, dev_t dev, ino_t ino)
2471e2328e7SCarlos Neira {
2481e2328e7SCarlos Neira return (ns->inum == ino) && (nsfs_mnt->mnt_sb->s_dev == dev);
2491e2328e7SCarlos Neira }
2501e2328e7SCarlos Neira
2511e2328e7SCarlos Neira
nsfs_show_path(struct seq_file * seq,struct dentry * dentry)25275509fd8SEric W. Biederman static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry)
25375509fd8SEric W. Biederman {
25475509fd8SEric W. Biederman struct inode *inode = d_inode(dentry);
25575509fd8SEric W. Biederman const struct proc_ns_operations *ns_ops = dentry->d_fsdata;
25675509fd8SEric W. Biederman
2576798a8caSJoe Perches seq_printf(seq, "%s:[%lu]", ns_ops->name, inode->i_ino);
2586798a8caSJoe Perches return 0;
25975509fd8SEric W. Biederman }
26075509fd8SEric W. Biederman
261e149ed2bSAl Viro static const struct super_operations nsfs_ops = {
262e149ed2bSAl Viro .statfs = simple_statfs,
263e149ed2bSAl Viro .evict_inode = nsfs_evict,
26475509fd8SEric W. Biederman .show_path = nsfs_show_path,
265e149ed2bSAl Viro };
266059b20d9SDavid Howells
nsfs_init_fs_context(struct fs_context * fc)267059b20d9SDavid Howells static int nsfs_init_fs_context(struct fs_context *fc)
268e149ed2bSAl Viro {
269059b20d9SDavid Howells struct pseudo_fs_context *ctx = init_pseudo(fc, NSFS_MAGIC);
270059b20d9SDavid Howells if (!ctx)
271059b20d9SDavid Howells return -ENOMEM;
272059b20d9SDavid Howells ctx->ops = &nsfs_ops;
273059b20d9SDavid Howells ctx->dops = &ns_dentry_operations;
274059b20d9SDavid Howells return 0;
275e149ed2bSAl Viro }
276059b20d9SDavid Howells
277e149ed2bSAl Viro static struct file_system_type nsfs = {
278e149ed2bSAl Viro .name = "nsfs",
279059b20d9SDavid Howells .init_fs_context = nsfs_init_fs_context,
280e149ed2bSAl Viro .kill_sb = kill_anon_super,
281e149ed2bSAl Viro };
282e149ed2bSAl Viro
nsfs_init(void)283e149ed2bSAl Viro void __init nsfs_init(void)
284e149ed2bSAl Viro {
285e149ed2bSAl Viro nsfs_mnt = kern_mount(&nsfs);
286e149ed2bSAl Viro if (IS_ERR(nsfs_mnt))
287e149ed2bSAl Viro panic("can't set nsfs up\n");
2881751e8a6SLinus Torvalds nsfs_mnt->mnt_sb->s_flags &= ~SB_NOUSER;
289e149ed2bSAl Viro }
290