1// SPDX-License-Identifier: GPL-2.0
2#include <linux/mount.h>
3#include <linux/pseudo_fs.h>
4#include <linux/file.h>
5#include <linux/fs.h>
6#include <linux/proc_fs.h>
7#include <linux/proc_ns.h>
8#include <linux/magic.h>
9#include <linux/ktime.h>
10#include <linux/seq_file.h>
11#include <linux/pid_namespace.h>
12#include <linux/user_namespace.h>
13#include <linux/nsfs.h>
14#include <linux/uaccess.h>
15#include <linux/mnt_namespace.h>
16
17#include "mount.h"
18#include "internal.h"
19
20static struct vfsmount *nsfs_mnt;
21
22static long ns_ioctl(struct file *filp, unsigned int ioctl,
23 unsigned long arg);
24static const struct file_operations ns_file_operations = {
25 .unlocked_ioctl = ns_ioctl,
26 .compat_ioctl = compat_ptr_ioctl,
27};
28
29static char *ns_dname(struct dentry *dentry, char *buffer, int buflen)
30{
31 struct inode *inode = d_inode(dentry);
32 struct ns_common *ns = inode->i_private;
33 const struct proc_ns_operations *ns_ops = ns->ops;
34
35 return dynamic_dname(buffer, buflen, "%s:[%lu]",
36 ns_ops->name, inode->i_ino);
37}
38
39const struct dentry_operations ns_dentry_operations = {
40 .d_dname = ns_dname,
41 .d_prune = stashed_dentry_prune,
42};
43
44static void nsfs_evict(struct inode *inode)
45{
46 struct ns_common *ns = inode->i_private;
47 clear_inode(inode);
48 ns->ops->put(ns);
49}
50
51int ns_get_path_cb(struct path *path, ns_get_path_helper_t *ns_get_cb,
52 void *private_data)
53{
54 struct ns_common *ns;
55
56 ns = ns_get_cb(private_data);
57 if (!ns)
58 return -ENOENT;
59
60 return path_from_stashed(stashed: &ns->stashed, mnt: nsfs_mnt, data: ns, path);
61}
62
63struct ns_get_path_task_args {
64 const struct proc_ns_operations *ns_ops;
65 struct task_struct *task;
66};
67
68static struct ns_common *ns_get_path_task(void *private_data)
69{
70 struct ns_get_path_task_args *args = private_data;
71
72 return args->ns_ops->get(args->task);
73}
74
75int ns_get_path(struct path *path, struct task_struct *task,
76 const struct proc_ns_operations *ns_ops)
77{
78 struct ns_get_path_task_args args = {
79 .ns_ops = ns_ops,
80 .task = task,
81 };
82
83 return ns_get_path_cb(path, ns_get_cb: ns_get_path_task, private_data: &args);
84}
85
86/**
87 * open_namespace - open a namespace
88 * @ns: the namespace to open
89 *
90 * This will consume a reference to @ns indendent of success or failure.
91 *
92 * Return: A file descriptor on success or a negative error code on failure.
93 */
94int open_namespace(struct ns_common *ns)
95{
96 struct path path __free(path_put) = {};
97 struct file *f;
98 int err;
99
100 /* call first to consume reference */
101 err = path_from_stashed(stashed: &ns->stashed, mnt: nsfs_mnt, data: ns, path: &path);
102 if (err < 0)
103 return err;
104
105 CLASS(get_unused_fd, fd)(O_CLOEXEC);
106 if (fd < 0)
107 return fd;
108
109 f = dentry_open(path: &path, O_RDONLY, current_cred());
110 if (IS_ERR(ptr: f))
111 return PTR_ERR(ptr: f);
112
113 fd_install(fd, file: f);
114 return take_fd(fd);
115}
116
117int open_related_ns(struct ns_common *ns,
118 struct ns_common *(*get_ns)(struct ns_common *ns))
119{
120 struct ns_common *relative;
121
122 relative = get_ns(ns);
123 if (IS_ERR(ptr: relative))
124 return PTR_ERR(ptr: relative);
125
126 return open_namespace(ns: relative);
127}
128EXPORT_SYMBOL_GPL(open_related_ns);
129
130static int copy_ns_info_to_user(const struct mnt_namespace *mnt_ns,
131 struct mnt_ns_info __user *uinfo, size_t usize,
132 struct mnt_ns_info *kinfo)
133{
134 /*
135 * If userspace and the kernel have the same struct size it can just
136 * be copied. If userspace provides an older struct, only the bits that
137 * userspace knows about will be copied. If userspace provides a new
138 * struct, only the bits that the kernel knows aobut will be copied and
139 * the size value will be set to the size the kernel knows about.
140 */
141 kinfo->size = min(usize, sizeof(*kinfo));
142 kinfo->mnt_ns_id = mnt_ns->seq;
143 kinfo->nr_mounts = READ_ONCE(mnt_ns->nr_mounts);
144 /* Subtract the root mount of the mount namespace. */
145 if (kinfo->nr_mounts)
146 kinfo->nr_mounts--;
147
148 if (copy_to_user(to: uinfo, from: kinfo, n: kinfo->size))
149 return -EFAULT;
150
151 return 0;
152}
153
154static bool nsfs_ioctl_valid(unsigned int cmd)
155{
156 switch (cmd) {
157 case NS_GET_USERNS:
158 case NS_GET_PARENT:
159 case NS_GET_NSTYPE:
160 case NS_GET_OWNER_UID:
161 case NS_GET_MNTNS_ID:
162 case NS_GET_PID_FROM_PIDNS:
163 case NS_GET_TGID_FROM_PIDNS:
164 case NS_GET_PID_IN_PIDNS:
165 case NS_GET_TGID_IN_PIDNS:
166 return (_IOC_TYPE(cmd) == _IOC_TYPE(cmd));
167 }
168
169 /* Extensible ioctls require some extra handling. */
170 switch (_IOC_NR(cmd)) {
171 case _IOC_NR(NS_MNT_GET_INFO):
172 case _IOC_NR(NS_MNT_GET_NEXT):
173 case _IOC_NR(NS_MNT_GET_PREV):
174 return (_IOC_TYPE(cmd) == _IOC_TYPE(cmd));
175 }
176
177 return false;
178}
179
180static long ns_ioctl(struct file *filp, unsigned int ioctl,
181 unsigned long arg)
182{
183 struct user_namespace *user_ns;
184 struct pid_namespace *pid_ns;
185 struct task_struct *tsk;
186 struct ns_common *ns;
187 struct mnt_namespace *mnt_ns;
188 bool previous = false;
189 uid_t __user *argp;
190 uid_t uid;
191 int ret;
192
193 if (!nsfs_ioctl_valid(cmd: ioctl))
194 return -ENOIOCTLCMD;
195
196 ns = get_proc_ns(file_inode(filp));
197 switch (ioctl) {
198 case NS_GET_USERNS:
199 return open_related_ns(ns, ns_get_owner);
200 case NS_GET_PARENT:
201 if (!ns->ops->get_parent)
202 return -EINVAL;
203 return open_related_ns(ns, ns->ops->get_parent);
204 case NS_GET_NSTYPE:
205 return ns->ops->type;
206 case NS_GET_OWNER_UID:
207 if (ns->ops->type != CLONE_NEWUSER)
208 return -EINVAL;
209 user_ns = container_of(ns, struct user_namespace, ns);
210 argp = (uid_t __user *) arg;
211 uid = from_kuid_munged(current_user_ns(), uid: user_ns->owner);
212 return put_user(uid, argp);
213 case NS_GET_MNTNS_ID: {
214 __u64 __user *idp;
215 __u64 id;
216
217 if (ns->ops->type != CLONE_NEWNS)
218 return -EINVAL;
219
220 mnt_ns = container_of(ns, struct mnt_namespace, ns);
221 idp = (__u64 __user *)arg;
222 id = mnt_ns->seq;
223 return put_user(id, idp);
224 }
225 case NS_GET_PID_FROM_PIDNS:
226 fallthrough;
227 case NS_GET_TGID_FROM_PIDNS:
228 fallthrough;
229 case NS_GET_PID_IN_PIDNS:
230 fallthrough;
231 case NS_GET_TGID_IN_PIDNS: {
232 if (ns->ops->type != CLONE_NEWPID)
233 return -EINVAL;
234
235 ret = -ESRCH;
236 pid_ns = container_of(ns, struct pid_namespace, ns);
237
238 guard(rcu)();
239
240 if (ioctl == NS_GET_PID_IN_PIDNS ||
241 ioctl == NS_GET_TGID_IN_PIDNS)
242 tsk = find_task_by_vpid(nr: arg);
243 else
244 tsk = find_task_by_pid_ns(nr: arg, ns: pid_ns);
245 if (!tsk)
246 break;
247
248 switch (ioctl) {
249 case NS_GET_PID_FROM_PIDNS:
250 ret = task_pid_vnr(tsk);
251 break;
252 case NS_GET_TGID_FROM_PIDNS:
253 ret = task_tgid_vnr(tsk);
254 break;
255 case NS_GET_PID_IN_PIDNS:
256 ret = task_pid_nr_ns(tsk, ns: pid_ns);
257 break;
258 case NS_GET_TGID_IN_PIDNS:
259 ret = task_tgid_nr_ns(tsk, ns: pid_ns);
260 break;
261 default:
262 ret = 0;
263 break;
264 }
265
266 if (!ret)
267 ret = -ESRCH;
268 return ret;
269 }
270 }
271
272 /* extensible ioctls */
273 switch (_IOC_NR(ioctl)) {
274 case _IOC_NR(NS_MNT_GET_INFO): {
275 struct mnt_ns_info kinfo = {};
276 struct mnt_ns_info __user *uinfo = (struct mnt_ns_info __user *)arg;
277 size_t usize = _IOC_SIZE(ioctl);
278
279 if (ns->ops->type != CLONE_NEWNS)
280 return -EINVAL;
281
282 if (!uinfo)
283 return -EINVAL;
284
285 if (usize < MNT_NS_INFO_SIZE_VER0)
286 return -EINVAL;
287
288 return copy_ns_info_to_user(mnt_ns: to_mnt_ns(ns), uinfo, usize, kinfo: &kinfo);
289 }
290 case _IOC_NR(NS_MNT_GET_PREV):
291 previous = true;
292 fallthrough;
293 case _IOC_NR(NS_MNT_GET_NEXT): {
294 struct mnt_ns_info kinfo = {};
295 struct mnt_ns_info __user *uinfo = (struct mnt_ns_info __user *)arg;
296 struct path path __free(path_put) = {};
297 struct file *f __free(fput) = NULL;
298 size_t usize = _IOC_SIZE(ioctl);
299
300 if (ns->ops->type != CLONE_NEWNS)
301 return -EINVAL;
302
303 if (usize < MNT_NS_INFO_SIZE_VER0)
304 return -EINVAL;
305
306 mnt_ns = get_sequential_mnt_ns(mnt_ns: to_mnt_ns(ns), previous);
307 if (IS_ERR(ptr: mnt_ns))
308 return PTR_ERR(ptr: mnt_ns);
309
310 ns = to_ns_common(mnt_ns);
311 /* Transfer ownership of @mnt_ns reference to @path. */
312 ret = path_from_stashed(stashed: &ns->stashed, mnt: nsfs_mnt, data: ns, path: &path);
313 if (ret)
314 return ret;
315
316 CLASS(get_unused_fd, fd)(O_CLOEXEC);
317 if (fd < 0)
318 return fd;
319
320 f = dentry_open(path: &path, O_RDONLY, current_cred());
321 if (IS_ERR(ptr: f))
322 return PTR_ERR(ptr: f);
323
324 if (uinfo) {
325 /*
326 * If @uinfo is passed return all information about the
327 * mount namespace as well.
328 */
329 ret = copy_ns_info_to_user(mnt_ns: to_mnt_ns(ns), uinfo, usize, kinfo: &kinfo);
330 if (ret)
331 return ret;
332 }
333
334 /* Transfer reference of @f to caller's fdtable. */
335 fd_install(fd, no_free_ptr(f));
336 /* File descriptor is live so hand it off to the caller. */
337 return take_fd(fd);
338 }
339 default:
340 ret = -ENOTTY;
341 }
342
343 return ret;
344}
345
346int ns_get_name(char *buf, size_t size, struct task_struct *task,
347 const struct proc_ns_operations *ns_ops)
348{
349 struct ns_common *ns;
350 int res = -ENOENT;
351 const char *name;
352 ns = ns_ops->get(task);
353 if (ns) {
354 name = ns_ops->real_ns_name ? : ns_ops->name;
355 res = snprintf(buf, size, fmt: "%s:[%u]", name, ns->inum);
356 ns_ops->put(ns);
357 }
358 return res;
359}
360
361bool proc_ns_file(const struct file *file)
362{
363 return file->f_op == &ns_file_operations;
364}
365
366/**
367 * ns_match() - Returns true if current namespace matches dev/ino provided.
368 * @ns: current namespace
369 * @dev: dev_t from nsfs that will be matched against current nsfs
370 * @ino: ino_t from nsfs that will be matched against current nsfs
371 *
372 * Return: true if dev and ino matches the current nsfs.
373 */
374bool ns_match(const struct ns_common *ns, dev_t dev, ino_t ino)
375{
376 return (ns->inum == ino) && (nsfs_mnt->mnt_sb->s_dev == dev);
377}
378
379
380static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry)
381{
382 struct inode *inode = d_inode(dentry);
383 const struct ns_common *ns = inode->i_private;
384 const struct proc_ns_operations *ns_ops = ns->ops;
385
386 seq_printf(m: seq, fmt: "%s:[%lu]", ns_ops->name, inode->i_ino);
387 return 0;
388}
389
390static const struct super_operations nsfs_ops = {
391 .statfs = simple_statfs,
392 .evict_inode = nsfs_evict,
393 .show_path = nsfs_show_path,
394};
395
396static int nsfs_init_inode(struct inode *inode, void *data)
397{
398 struct ns_common *ns = data;
399
400 inode->i_private = data;
401 inode->i_mode |= S_IRUGO;
402 inode->i_fop = &ns_file_operations;
403 inode->i_ino = ns->inum;
404 return 0;
405}
406
407static void nsfs_put_data(void *data)
408{
409 struct ns_common *ns = data;
410 ns->ops->put(ns);
411}
412
413static const struct stashed_operations nsfs_stashed_ops = {
414 .init_inode = nsfs_init_inode,
415 .put_data = nsfs_put_data,
416};
417
418static int nsfs_init_fs_context(struct fs_context *fc)
419{
420 struct pseudo_fs_context *ctx = init_pseudo(fc, NSFS_MAGIC);
421 if (!ctx)
422 return -ENOMEM;
423 ctx->ops = &nsfs_ops;
424 ctx->dops = &ns_dentry_operations;
425 fc->s_fs_info = (void *)&nsfs_stashed_ops;
426 return 0;
427}
428
429static struct file_system_type nsfs = {
430 .name = "nsfs",
431 .init_fs_context = nsfs_init_fs_context,
432 .kill_sb = kill_anon_super,
433};
434
435void __init nsfs_init(void)
436{
437 nsfs_mnt = kern_mount(&nsfs);
438 if (IS_ERR(ptr: nsfs_mnt))
439 panic(fmt: "can't set nsfs up\n");
440 nsfs_mnt->mnt_sb->s_flags &= ~SB_NOUSER;
441}
442

Provided by KDAB

Privacy Policy
Improve your Profiling and Debugging skills
Find out more

source code of linux/fs/nsfs.c