fs: add mount_setattr()
[linux-block.git] / fs / proc_namespace.c
CommitLineData
b2441318 1// SPDX-License-Identifier: GPL-2.0
0226f492
AV
2/*
3 * fs/proc_namespace.c - handling of /proc/<pid>/{mounts,mountinfo,mountstats}
4 *
5 * In fact, that's a piece of procfs; it's *almost* isolated from
6 * the rest of fs/proc, but has rather close relationships with
7 * fs/namespace.c, thus here instead of fs/proc
8 *
9 */
10#include <linux/mnt_namespace.h>
11#include <linux/nsproxy.h>
12#include <linux/security.h>
13#include <linux/fs_struct.h>
f719ff9b
IM
14#include <linux/sched/task.h>
15
0226f492
AV
16#include "proc/internal.h" /* only for get_proc_task() in ->open() */
17
18#include "pnode.h"
19#include "internal.h"
20
076ccb76 21static __poll_t mounts_poll(struct file *file, poll_table *wait)
0226f492 22{
ede1bf0d
YD
23 struct seq_file *m = file->private_data;
24 struct proc_mounts *p = m->private;
0226f492 25 struct mnt_namespace *ns = p->ns;
a9a08845 26 __poll_t res = EPOLLIN | EPOLLRDNORM;
aab407fc 27 int event;
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AV
28
29 poll_wait(file, &p->ns->poll, wait);
30
6aa7de05 31 event = READ_ONCE(ns->event);
ede1bf0d
YD
32 if (m->poll_event != event) {
33 m->poll_event = event;
a9a08845 34 res |= EPOLLERR | EPOLLPRI;
0226f492 35 }
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AV
36
37 return res;
38}
39
1e88c420 40struct proc_fs_opts {
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AV
41 int flag;
42 const char *str;
43};
44
45static int show_sb_opts(struct seq_file *m, struct super_block *sb)
46{
1e88c420 47 static const struct proc_fs_opts fs_opts[] = {
1751e8a6
LT
48 { SB_SYNCHRONOUS, ",sync" },
49 { SB_DIRSYNC, ",dirsync" },
50 { SB_MANDLOCK, ",mand" },
51 { SB_LAZYTIME, ",lazytime" },
0226f492
AV
52 { 0, NULL }
53 };
1e88c420 54 const struct proc_fs_opts *fs_infop;
0226f492 55
1e88c420 56 for (fs_infop = fs_opts; fs_infop->flag; fs_infop++) {
0226f492
AV
57 if (sb->s_flags & fs_infop->flag)
58 seq_puts(m, fs_infop->str);
59 }
60
61 return security_sb_show_options(m, sb);
62}
63
64static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
65{
1e88c420 66 static const struct proc_fs_opts mnt_opts[] = {
0226f492
AV
67 { MNT_NOSUID, ",nosuid" },
68 { MNT_NODEV, ",nodev" },
69 { MNT_NOEXEC, ",noexec" },
70 { MNT_NOATIME, ",noatime" },
71 { MNT_NODIRATIME, ",nodiratime" },
72 { MNT_RELATIME, ",relatime" },
dab741e0 73 { MNT_NOSYMFOLLOW, ",nosymfollow" },
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AV
74 { 0, NULL }
75 };
1e88c420 76 const struct proc_fs_opts *fs_infop;
0226f492 77
1e88c420 78 for (fs_infop = mnt_opts; fs_infop->flag; fs_infop++) {
0226f492
AV
79 if (mnt->mnt_flags & fs_infop->flag)
80 seq_puts(m, fs_infop->str);
81 }
82}
83
84static inline void mangle(struct seq_file *m, const char *s)
85{
86 seq_escape(m, s, " \t\n\\");
87}
88
89static void show_type(struct seq_file *m, struct super_block *sb)
90{
91 mangle(m, sb->s_type->name);
c7eb6869 92 if (sb->s_subtype) {
0226f492
AV
93 seq_putc(m, '.');
94 mangle(m, sb->s_subtype);
95 }
96}
97
98static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)
99{
ede1bf0d 100 struct proc_mounts *p = m->private;
0226f492 101 struct mount *r = real_mount(mnt);
0226f492 102 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
d861c630 103 struct super_block *sb = mnt_path.dentry->d_sb;
5d9f3c7b 104 int err;
0226f492 105
d861c630
AV
106 if (sb->s_op->show_devname) {
107 err = sb->s_op->show_devname(m, mnt_path.dentry);
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AV
108 if (err)
109 goto out;
110 } else {
111 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
112 }
113 seq_putc(m, ' ');
9d4d6574
DL
114 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
115 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
116 if (err)
117 goto out;
0226f492 118 seq_putc(m, ' ');
d861c630 119 show_type(m, sb);
0226f492 120 seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
d861c630 121 err = show_sb_opts(m, sb);
0226f492
AV
122 if (err)
123 goto out;
124 show_mnt_opts(m, mnt);
d861c630 125 if (sb->s_op->show_options)
34c80b1d 126 err = sb->s_op->show_options(m, mnt_path.dentry);
0226f492
AV
127 seq_puts(m, " 0 0\n");
128out:
129 return err;
130}
131
132static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
133{
ede1bf0d 134 struct proc_mounts *p = m->private;
0226f492
AV
135 struct mount *r = real_mount(mnt);
136 struct super_block *sb = mnt->mnt_sb;
137 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
6ce4bca0 138 int err;
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AV
139
140 seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id,
141 MAJOR(sb->s_dev), MINOR(sb->s_dev));
6ce4bca0 142 if (sb->s_op->show_path) {
a6322de6 143 err = sb->s_op->show_path(m, mnt->mnt_root);
6ce4bca0
DL
144 if (err)
145 goto out;
146 } else {
0226f492 147 seq_dentry(m, mnt->mnt_root, " \t\n\\");
6ce4bca0 148 }
0226f492
AV
149 seq_putc(m, ' ');
150
151 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
9ad4dc4f 152 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
0226f492
AV
153 if (err)
154 goto out;
155
156 seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
157 show_mnt_opts(m, mnt);
158
159 /* Tagged fields ("foo:X" or "bar") */
160 if (IS_MNT_SHARED(r))
161 seq_printf(m, " shared:%i", r->mnt_group_id);
162 if (IS_MNT_SLAVE(r)) {
163 int master = r->mnt_master->mnt_group_id;
164 int dom = get_dominating_id(r, &p->root);
165 seq_printf(m, " master:%i", master);
166 if (dom && dom != master)
167 seq_printf(m, " propagate_from:%i", dom);
168 }
169 if (IS_MNT_UNBINDABLE(r))
170 seq_puts(m, " unbindable");
171
172 /* Filesystem specific data */
173 seq_puts(m, " - ");
174 show_type(m, sb);
175 seq_putc(m, ' ');
6ce4bca0 176 if (sb->s_op->show_devname) {
d861c630 177 err = sb->s_op->show_devname(m, mnt->mnt_root);
6ce4bca0
DL
178 if (err)
179 goto out;
180 } else {
0226f492 181 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
6ce4bca0 182 }
bc98a42c 183 seq_puts(m, sb_rdonly(sb) ? " ro" : " rw");
0226f492
AV
184 err = show_sb_opts(m, sb);
185 if (err)
186 goto out;
187 if (sb->s_op->show_options)
34c80b1d 188 err = sb->s_op->show_options(m, mnt->mnt_root);
0226f492
AV
189 seq_putc(m, '\n');
190out:
191 return err;
192}
193
194static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt)
195{
ede1bf0d 196 struct proc_mounts *p = m->private;
0226f492
AV
197 struct mount *r = real_mount(mnt);
198 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
64132379 199 struct super_block *sb = mnt_path.dentry->d_sb;
b896fb35 200 int err;
0226f492
AV
201
202 /* device */
64132379 203 if (sb->s_op->show_devname) {
0226f492 204 seq_puts(m, "device ");
d861c630 205 err = sb->s_op->show_devname(m, mnt_path.dentry);
5f8d498d
DL
206 if (err)
207 goto out;
0226f492
AV
208 } else {
209 if (r->mnt_devname) {
210 seq_puts(m, "device ");
211 mangle(m, r->mnt_devname);
212 } else
213 seq_puts(m, "no device");
214 }
215
216 /* mount point */
217 seq_puts(m, " mounted on ");
9d4d6574
DL
218 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
219 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
220 if (err)
221 goto out;
0226f492
AV
222 seq_putc(m, ' ');
223
224 /* file system type */
225 seq_puts(m, "with fstype ");
64132379 226 show_type(m, sb);
0226f492
AV
227
228 /* optional statistics */
64132379 229 if (sb->s_op->show_stats) {
0226f492 230 seq_putc(m, ' ');
b896fb35 231 err = sb->s_op->show_stats(m, mnt_path.dentry);
0226f492
AV
232 }
233
234 seq_putc(m, '\n');
9d4d6574 235out:
0226f492
AV
236 return err;
237}
238
239static int mounts_open_common(struct inode *inode, struct file *file,
240 int (*show)(struct seq_file *, struct vfsmount *))
241{
242 struct task_struct *task = get_proc_task(inode);
243 struct nsproxy *nsp;
244 struct mnt_namespace *ns = NULL;
245 struct path root;
246 struct proc_mounts *p;
ede1bf0d 247 struct seq_file *m;
0226f492
AV
248 int ret = -EINVAL;
249
250 if (!task)
251 goto err;
252
728dba3a
EB
253 task_lock(task);
254 nsp = task->nsproxy;
3d93116c 255 if (!nsp || !nsp->mnt_ns) {
728dba3a 256 task_unlock(task);
0226f492
AV
257 put_task_struct(task);
258 goto err;
259 }
260 ns = nsp->mnt_ns;
0226f492 261 get_mnt_ns(ns);
0226f492
AV
262 if (!task->fs) {
263 task_unlock(task);
264 put_task_struct(task);
265 ret = -ENOENT;
266 goto err_put_ns;
267 }
268 get_fs_root(task->fs, &root);
269 task_unlock(task);
270 put_task_struct(task);
271
ede1bf0d
YD
272 ret = seq_open_private(file, &mounts_op, sizeof(struct proc_mounts));
273 if (ret)
0226f492
AV
274 goto err_put_path;
275
ede1bf0d
YD
276 m = file->private_data;
277 m->poll_event = ns->event;
0226f492 278
ede1bf0d 279 p = m->private;
0226f492
AV
280 p->ns = ns;
281 p->root = root;
0226f492 282 p->show = show;
9f6c61f9
MS
283 INIT_LIST_HEAD(&p->cursor.mnt_list);
284 p->cursor.mnt.mnt_flags = MNT_CURSOR;
0226f492
AV
285
286 return 0;
287
0226f492
AV
288 err_put_path:
289 path_put(&root);
290 err_put_ns:
291 put_mnt_ns(ns);
292 err:
293 return ret;
294}
295
296static int mounts_release(struct inode *inode, struct file *file)
297{
ede1bf0d
YD
298 struct seq_file *m = file->private_data;
299 struct proc_mounts *p = m->private;
0226f492 300 path_put(&p->root);
9f6c61f9 301 mnt_cursor_del(p->ns, &p->cursor);
0226f492 302 put_mnt_ns(p->ns);
ede1bf0d 303 return seq_release_private(inode, file);
0226f492
AV
304}
305
306static int mounts_open(struct inode *inode, struct file *file)
307{
308 return mounts_open_common(inode, file, show_vfsmnt);
309}
310
311static int mountinfo_open(struct inode *inode, struct file *file)
312{
313 return mounts_open_common(inode, file, show_mountinfo);
314}
315
316static int mountstats_open(struct inode *inode, struct file *file)
317{
318 return mounts_open_common(inode, file, show_vfsstat);
319}
320
321const struct file_operations proc_mounts_operations = {
322 .open = mounts_open,
14e3e989
LT
323 .read_iter = seq_read_iter,
324 .splice_read = generic_file_splice_read,
0226f492
AV
325 .llseek = seq_lseek,
326 .release = mounts_release,
327 .poll = mounts_poll,
328};
329
330const struct file_operations proc_mountinfo_operations = {
331 .open = mountinfo_open,
14e3e989
LT
332 .read_iter = seq_read_iter,
333 .splice_read = generic_file_splice_read,
0226f492
AV
334 .llseek = seq_lseek,
335 .release = mounts_release,
336 .poll = mounts_poll,
337};
338
339const struct file_operations proc_mountstats_operations = {
340 .open = mountstats_open,
14e3e989
LT
341 .read_iter = seq_read_iter,
342 .splice_read = generic_file_splice_read,
0226f492
AV
343 .llseek = seq_lseek,
344 .release = mounts_release,
345};