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
mounts_poll(struct file * file,poll_table * wait)21 static __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
40 struct proc_fs_info {
41 int flag;
42 const char *str;
43 };
44
show_sb_opts(struct seq_file * m,struct super_block * sb)45 static int show_sb_opts(struct seq_file *m, struct super_block *sb)
46 {
47 static const struct proc_fs_info fs_info[] = {
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_info *fs_infop;
55
56 for (fs_infop = fs_info; 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
show_mnt_opts(struct seq_file * m,struct vfsmount * mnt)64 static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
65 {
66 static const struct proc_fs_info mnt_info[] = {
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 { 0, NULL }
74 };
75 const struct proc_fs_info *fs_infop;
76
77 for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
78 if (mnt->mnt_flags & fs_infop->flag)
79 seq_puts(m, fs_infop->str);
80 }
81 }
82
mangle(struct seq_file * m,const char * s)83 static inline void mangle(struct seq_file *m, const char *s)
84 {
85 seq_escape(m, s, " \t\n\\");
86 }
87
show_type(struct seq_file * m,struct super_block * sb)88 static void show_type(struct seq_file *m, struct super_block *sb)
89 {
90 mangle(m, sb->s_type->name);
91 if (sb->s_subtype) {
92 seq_putc(m, '.');
93 mangle(m, sb->s_subtype);
94 }
95 }
96
show_vfsmnt(struct seq_file * m,struct vfsmount * mnt)97 static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)
98 {
99 struct proc_mounts *p = m->private;
100 struct mount *r = real_mount(mnt);
101 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
102 struct super_block *sb = mnt_path.dentry->d_sb;
103 int err;
104
105 if (sb->s_op->show_devname) {
106 err = sb->s_op->show_devname(m, mnt_path.dentry);
107 if (err)
108 goto out;
109 } else {
110 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
111 }
112 seq_putc(m, ' ');
113 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
114 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
115 if (err)
116 goto out;
117 seq_putc(m, ' ');
118 show_type(m, sb);
119 seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
120 err = show_sb_opts(m, sb);
121 if (err)
122 goto out;
123 show_mnt_opts(m, mnt);
124 if (sb->s_op->show_options2)
125 err = sb->s_op->show_options2(mnt, m, mnt_path.dentry);
126 else if (sb->s_op->show_options)
127 err = sb->s_op->show_options(m, mnt_path.dentry);
128 seq_puts(m, " 0 0\n");
129 out:
130 return err;
131 }
132
show_mountinfo(struct seq_file * m,struct vfsmount * mnt)133 static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
134 {
135 struct proc_mounts *p = m->private;
136 struct mount *r = real_mount(mnt);
137 struct super_block *sb = mnt->mnt_sb;
138 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
139 int err;
140
141 seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id,
142 MAJOR(sb->s_dev), MINOR(sb->s_dev));
143 if (sb->s_op->show_path) {
144 err = sb->s_op->show_path(m, mnt->mnt_root);
145 if (err)
146 goto out;
147 } else {
148 seq_dentry(m, mnt->mnt_root, " \t\n\\");
149 }
150 seq_putc(m, ' ');
151
152 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
153 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
154 if (err)
155 goto out;
156
157 seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
158 show_mnt_opts(m, mnt);
159
160 /* Tagged fields ("foo:X" or "bar") */
161 if (IS_MNT_SHARED(r))
162 seq_printf(m, " shared:%i", r->mnt_group_id);
163 if (IS_MNT_SLAVE(r)) {
164 int master = r->mnt_master->mnt_group_id;
165 int dom = get_dominating_id(r, &p->root);
166 seq_printf(m, " master:%i", master);
167 if (dom && dom != master)
168 seq_printf(m, " propagate_from:%i", dom);
169 }
170 if (IS_MNT_UNBINDABLE(r))
171 seq_puts(m, " unbindable");
172
173 /* Filesystem specific data */
174 seq_puts(m, " - ");
175 show_type(m, sb);
176 seq_putc(m, ' ');
177 if (sb->s_op->show_devname) {
178 err = sb->s_op->show_devname(m, mnt->mnt_root);
179 if (err)
180 goto out;
181 } else {
182 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
183 }
184 seq_puts(m, sb_rdonly(sb) ? " ro" : " rw");
185 err = show_sb_opts(m, sb);
186 if (err)
187 goto out;
188 if (sb->s_op->show_options2) {
189 err = sb->s_op->show_options2(mnt, m, mnt->mnt_root);
190 } else if (sb->s_op->show_options)
191 err = sb->s_op->show_options(m, mnt->mnt_root);
192 seq_putc(m, '\n');
193 out:
194 return err;
195 }
196
show_vfsstat(struct seq_file * m,struct vfsmount * mnt)197 static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt)
198 {
199 struct proc_mounts *p = m->private;
200 struct mount *r = real_mount(mnt);
201 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
202 struct super_block *sb = mnt_path.dentry->d_sb;
203 int err;
204
205 /* device */
206 if (sb->s_op->show_devname) {
207 seq_puts(m, "device ");
208 err = sb->s_op->show_devname(m, mnt_path.dentry);
209 if (err)
210 goto out;
211 } else {
212 if (r->mnt_devname) {
213 seq_puts(m, "device ");
214 mangle(m, r->mnt_devname);
215 } else
216 seq_puts(m, "no device");
217 }
218
219 /* mount point */
220 seq_puts(m, " mounted on ");
221 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
222 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
223 if (err)
224 goto out;
225 seq_putc(m, ' ');
226
227 /* file system type */
228 seq_puts(m, "with fstype ");
229 show_type(m, sb);
230
231 /* optional statistics */
232 if (sb->s_op->show_stats) {
233 seq_putc(m, ' ');
234 err = sb->s_op->show_stats(m, mnt_path.dentry);
235 }
236
237 seq_putc(m, '\n');
238 out:
239 return err;
240 }
241
mounts_open_common(struct inode * inode,struct file * file,int (* show)(struct seq_file *,struct vfsmount *))242 static int mounts_open_common(struct inode *inode, struct file *file,
243 int (*show)(struct seq_file *, struct vfsmount *))
244 {
245 struct task_struct *task = get_proc_task(inode);
246 struct nsproxy *nsp;
247 struct mnt_namespace *ns = NULL;
248 struct path root;
249 struct proc_mounts *p;
250 struct seq_file *m;
251 int ret = -EINVAL;
252
253 if (!task)
254 goto err;
255
256 task_lock(task);
257 nsp = task->nsproxy;
258 if (!nsp || !nsp->mnt_ns) {
259 task_unlock(task);
260 put_task_struct(task);
261 goto err;
262 }
263 ns = nsp->mnt_ns;
264 get_mnt_ns(ns);
265 if (!task->fs) {
266 task_unlock(task);
267 put_task_struct(task);
268 ret = -ENOENT;
269 goto err_put_ns;
270 }
271 get_fs_root(task->fs, &root);
272 task_unlock(task);
273 put_task_struct(task);
274
275 ret = seq_open_private(file, &mounts_op, sizeof(struct proc_mounts));
276 if (ret)
277 goto err_put_path;
278
279 m = file->private_data;
280 m->poll_event = ns->event;
281
282 p = m->private;
283 p->ns = ns;
284 p->root = root;
285 p->show = show;
286 p->cached_event = ~0ULL;
287
288 return 0;
289
290 err_put_path:
291 path_put(&root);
292 err_put_ns:
293 put_mnt_ns(ns);
294 err:
295 return ret;
296 }
297
mounts_release(struct inode * inode,struct file * file)298 static int mounts_release(struct inode *inode, struct file *file)
299 {
300 struct seq_file *m = file->private_data;
301 struct proc_mounts *p = m->private;
302 path_put(&p->root);
303 put_mnt_ns(p->ns);
304 return seq_release_private(inode, file);
305 }
306
mounts_open(struct inode * inode,struct file * file)307 static int mounts_open(struct inode *inode, struct file *file)
308 {
309 return mounts_open_common(inode, file, show_vfsmnt);
310 }
311
mountinfo_open(struct inode * inode,struct file * file)312 static int mountinfo_open(struct inode *inode, struct file *file)
313 {
314 return mounts_open_common(inode, file, show_mountinfo);
315 }
316
mountstats_open(struct inode * inode,struct file * file)317 static int mountstats_open(struct inode *inode, struct file *file)
318 {
319 return mounts_open_common(inode, file, show_vfsstat);
320 }
321
322 const struct file_operations proc_mounts_operations = {
323 .open = mounts_open,
324 .read = seq_read,
325 .llseek = seq_lseek,
326 .release = mounts_release,
327 .poll = mounts_poll,
328 };
329
330 const struct file_operations proc_mountinfo_operations = {
331 .open = mountinfo_open,
332 .read = seq_read,
333 .llseek = seq_lseek,
334 .release = mounts_release,
335 .poll = mounts_poll,
336 };
337
338 const struct file_operations proc_mountstats_operations = {
339 .open = mountstats_open,
340 .read = seq_read,
341 .llseek = seq_lseek,
342 .release = mounts_release,
343 };
344