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337 lines · 7.8 KiB

1// SPDX-License-Identifier: GPL-2.0
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>
14#include <linux/sched/task.h>
15
16#include "proc/internal.h" /* only for get_proc_task() in ->open() */
17
18#include "pnode.h"
19#include "internal.h"
20
21static __poll_t mounts_poll(struct file *file, poll_table *wait)
22{
23 struct seq_file *m = file->private_data;
24 struct proc_mounts *p = m->private;
25 struct mnt_namespace *ns = p->ns;
26 __poll_t res = EPOLLIN | EPOLLRDNORM;
27 int event;
28
29 poll_wait(file, &p->ns->poll, wait);
30
31 event = READ_ONCE(ns->event);
32 if (m->poll_event != event) {
33 m->poll_event = event;
34 res |= EPOLLERR | EPOLLPRI;
35 }
36
37 return res;
38}
39
40struct proc_fs_opts {
41 int flag;
42 const char *str;
43};
44
45static int show_sb_opts(struct seq_file *m, struct super_block *sb)
46{
47 static const struct proc_fs_opts fs_opts[] = {
48 { SB_SYNCHRONOUS, ",sync" },
49 { SB_DIRSYNC, ",dirsync" },
50 { SB_MANDLOCK, ",mand" },
51 { SB_LAZYTIME, ",lazytime" },
52 { 0, NULL }
53 };
54 const struct proc_fs_opts *fs_infop;
55
56 for (fs_infop = fs_opts; fs_infop->flag; fs_infop++) {
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_vfsmnt_opts(struct seq_file *m, struct vfsmount *mnt)
65{
66 static const struct proc_fs_opts mnt_opts[] = {
67 { MNT_NOSUID, ",nosuid" },
68 { MNT_NODEV, ",nodev" },
69 { MNT_NOEXEC, ",noexec" },
70 { MNT_NOATIME, ",noatime" },
71 { MNT_NODIRATIME, ",nodiratime" },
72 { MNT_RELATIME, ",relatime" },
73 { MNT_NOSYMFOLLOW, ",nosymfollow" },
74 { 0, NULL }
75 };
76 const struct proc_fs_opts *fs_infop;
77
78 for (fs_infop = mnt_opts; fs_infop->flag; fs_infop++) {
79 if (mnt->mnt_flags & fs_infop->flag)
80 seq_puts(m, fs_infop->str);
81 }
82
83 if (is_idmapped_mnt(mnt))
84 seq_puts(m, ",idmapped");
85}
86
87static inline void mangle(struct seq_file *m, const char *s)
88{
89 seq_escape(m, s, " \t\n\\#");
90}
91
92static void show_type(struct seq_file *m, struct super_block *sb)
93{
94 mangle(m, sb->s_type->name);
95 if (sb->s_subtype) {
96 seq_putc(m, '.');
97 mangle(m, sb->s_subtype);
98 }
99}
100
101static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)
102{
103 struct proc_mounts *p = m->private;
104 struct mount *r = real_mount(mnt);
105 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
106 struct super_block *sb = mnt_path.dentry->d_sb;
107 int err;
108
109 if (sb->s_op->show_devname) {
110 err = sb->s_op->show_devname(m, mnt_path.dentry);
111 if (err)
112 goto out;
113 } else {
114 mangle(m, r->mnt_devname);
115 }
116 seq_putc(m, ' ');
117 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
118 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
119 if (err)
120 goto out;
121 seq_putc(m, ' ');
122 show_type(m, sb);
123 seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
124 err = show_sb_opts(m, sb);
125 if (err)
126 goto out;
127 show_vfsmnt_opts(m, mnt);
128 if (sb->s_op->show_options)
129 err = sb->s_op->show_options(m, mnt_path.dentry);
130 seq_puts(m, " 0 0\n");
131out:
132 return err;
133}
134
135static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
136{
137 struct proc_mounts *p = m->private;
138 struct mount *r = real_mount(mnt);
139 struct super_block *sb = mnt->mnt_sb;
140 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
141 int err;
142
143 seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id,
144 MAJOR(sb->s_dev), MINOR(sb->s_dev));
145 err = show_path(m, mnt->mnt_root);
146 if (err)
147 goto out;
148 seq_putc(m, ' ');
149
150 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
151 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
152 if (err)
153 goto out;
154
155 seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
156 show_vfsmnt_opts(m, mnt);
157
158 /* Tagged fields ("foo:X" or "bar") */
159 if (IS_MNT_SHARED(r))
160 seq_printf(m, " shared:%i", r->mnt_group_id);
161 if (IS_MNT_SLAVE(r)) {
162 int master = r->mnt_master->mnt_group_id;
163 int dom = get_dominating_id(r, &p->root);
164 seq_printf(m, " master:%i", master);
165 if (dom && dom != master)
166 seq_printf(m, " propagate_from:%i", dom);
167 }
168 if (IS_MNT_UNBINDABLE(r))
169 seq_puts(m, " unbindable");
170
171 /* Filesystem specific data */
172 seq_puts(m, " - ");
173 show_type(m, sb);
174 seq_putc(m, ' ');
175 if (sb->s_op->show_devname) {
176 err = sb->s_op->show_devname(m, mnt->mnt_root);
177 if (err)
178 goto out;
179 } else {
180 mangle(m, r->mnt_devname);
181 }
182 seq_puts(m, sb_rdonly(sb) ? " ro" : " rw");
183 err = show_sb_opts(m, sb);
184 if (err)
185 goto out;
186 if (sb->s_op->show_options)
187 err = sb->s_op->show_options(m, mnt->mnt_root);
188 seq_putc(m, '\n');
189out:
190 return err;
191}
192
193static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt)
194{
195 struct proc_mounts *p = m->private;
196 struct mount *r = real_mount(mnt);
197 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
198 struct super_block *sb = mnt_path.dentry->d_sb;
199 int err;
200
201 /* device */
202 seq_puts(m, "device ");
203 if (sb->s_op->show_devname) {
204 err = sb->s_op->show_devname(m, mnt_path.dentry);
205 if (err)
206 goto out;
207 } else {
208 mangle(m, r->mnt_devname);
209 }
210
211 /* mount point */
212 seq_puts(m, " mounted on ");
213 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
214 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
215 if (err)
216 goto out;
217 seq_putc(m, ' ');
218
219 /* file system type */
220 seq_puts(m, "with fstype ");
221 show_type(m, sb);
222
223 /* optional statistics */
224 if (sb->s_op->show_stats) {
225 seq_putc(m, ' ');
226 err = sb->s_op->show_stats(m, mnt_path.dentry);
227 }
228
229 seq_putc(m, '\n');
230out:
231 return err;
232}
233
234static int mounts_open_common(struct inode *inode, struct file *file,
235 int (*show)(struct seq_file *, struct vfsmount *))
236{
237 struct task_struct *task = get_proc_task(inode);
238 struct nsproxy *nsp;
239 struct mnt_namespace *ns = NULL;
240 struct path root;
241 struct proc_mounts *p;
242 struct seq_file *m;
243 int ret = -EINVAL;
244
245 if (!task)
246 goto err;
247
248 task_lock(task);
249 nsp = task->nsproxy;
250 if (!nsp || !nsp->mnt_ns) {
251 task_unlock(task);
252 put_task_struct(task);
253 goto err;
254 }
255 ns = nsp->mnt_ns;
256 get_mnt_ns(ns);
257 if (!task->real_fs) {
258 task_unlock(task);
259 put_task_struct(task);
260 ret = -ENOENT;
261 goto err_put_ns;
262 }
263 get_fs_root(task->real_fs, &root);
264 task_unlock(task);
265 put_task_struct(task);
266
267 ret = seq_open_private(file, &mounts_op, sizeof(struct proc_mounts));
268 if (ret)
269 goto err_put_path;
270
271 m = file->private_data;
272 m->poll_event = ns->event;
273
274 p = m->private;
275 p->ns = ns;
276 p->root = root;
277 p->show = show;
278
279 return 0;
280
281 err_put_path:
282 path_put(&root);
283 err_put_ns:
284 put_mnt_ns(ns);
285 err:
286 return ret;
287}
288
289static int mounts_release(struct inode *inode, struct file *file)
290{
291 struct seq_file *m = file->private_data;
292 struct proc_mounts *p = m->private;
293 path_put(&p->root);
294 put_mnt_ns(p->ns);
295 return seq_release_private(inode, file);
296}
297
298static int mounts_open(struct inode *inode, struct file *file)
299{
300 return mounts_open_common(inode, file, show_vfsmnt);
301}
302
303static int mountinfo_open(struct inode *inode, struct file *file)
304{
305 return mounts_open_common(inode, file, show_mountinfo);
306}
307
308static int mountstats_open(struct inode *inode, struct file *file)
309{
310 return mounts_open_common(inode, file, show_vfsstat);
311}
312
313const struct file_operations proc_mounts_operations = {
314 .open = mounts_open,
315 .read_iter = seq_read_iter,
316 .splice_read = copy_splice_read,
317 .llseek = seq_lseek,
318 .release = mounts_release,
319 .poll = mounts_poll,
320};
321
322const struct file_operations proc_mountinfo_operations = {
323 .open = mountinfo_open,
324 .read_iter = seq_read_iter,
325 .splice_read = copy_splice_read,
326 .llseek = seq_lseek,
327 .release = mounts_release,
328 .poll = mounts_poll,
329};
330
331const struct file_operations proc_mountstats_operations = {
332 .open = mountstats_open,
333 .read_iter = seq_read_iter,
334 .splice_read = copy_splice_read,
335 .llseek = seq_lseek,
336 .release = mounts_release,
337};