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_opts {
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_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
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_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
mangle(struct seq_file * m,const char * s)87 static inline void mangle(struct seq_file *m, const char *s)
88 {
89 seq_escape(m, s, " \t\n\\#");
90 }
91
show_type(struct seq_file * m,struct super_block * sb)92 static 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
show_vfsmnt(struct seq_file * m,struct vfsmount * mnt)101 static 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 ? r->mnt_devname : "none");
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_mnt_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");
131 out:
132 return err;
133 }
134
show_mountinfo(struct seq_file * m,struct vfsmount * mnt)135 static 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 if (sb->s_op->show_path) {
146 err = sb->s_op->show_path(m, mnt->mnt_root);
147 if (err)
148 goto out;
149 } else {
150 seq_dentry(m, mnt->mnt_root, " \t\n\\");
151 }
152 seq_putc(m, ' ');
153
154 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
155 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
156 if (err)
157 goto out;
158
159 seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
160 show_mnt_opts(m, mnt);
161
162 /* Tagged fields ("foo:X" or "bar") */
163 if (IS_MNT_SHARED(r))
164 seq_printf(m, " shared:%i", r->mnt_group_id);
165 if (IS_MNT_SLAVE(r)) {
166 int master = r->mnt_master->mnt_group_id;
167 int dom = get_dominating_id(r, &p->root);
168 seq_printf(m, " master:%i", master);
169 if (dom && dom != master)
170 seq_printf(m, " propagate_from:%i", dom);
171 }
172 if (IS_MNT_UNBINDABLE(r))
173 seq_puts(m, " unbindable");
174
175 /* Filesystem specific data */
176 seq_puts(m, " - ");
177 show_type(m, sb);
178 seq_putc(m, ' ');
179 if (sb->s_op->show_devname) {
180 err = sb->s_op->show_devname(m, mnt->mnt_root);
181 if (err)
182 goto out;
183 } else {
184 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
185 }
186 seq_puts(m, sb_rdonly(sb) ? " ro" : " rw");
187 err = show_sb_opts(m, sb);
188 if (err)
189 goto out;
190 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 INIT_LIST_HEAD(&p->cursor.mnt_list);
287 p->cursor.mnt.mnt_flags = MNT_CURSOR;
288
289 return 0;
290
291 err_put_path:
292 path_put(&root);
293 err_put_ns:
294 put_mnt_ns(ns);
295 err:
296 return ret;
297 }
298
mounts_release(struct inode * inode,struct file * file)299 static int mounts_release(struct inode *inode, struct file *file)
300 {
301 struct seq_file *m = file->private_data;
302 struct proc_mounts *p = m->private;
303 path_put(&p->root);
304 mnt_cursor_del(p->ns, &p->cursor);
305 put_mnt_ns(p->ns);
306 return seq_release_private(inode, file);
307 }
308
mounts_open(struct inode * inode,struct file * file)309 static int mounts_open(struct inode *inode, struct file *file)
310 {
311 return mounts_open_common(inode, file, show_vfsmnt);
312 }
313
mountinfo_open(struct inode * inode,struct file * file)314 static int mountinfo_open(struct inode *inode, struct file *file)
315 {
316 return mounts_open_common(inode, file, show_mountinfo);
317 }
318
mountstats_open(struct inode * inode,struct file * file)319 static int mountstats_open(struct inode *inode, struct file *file)
320 {
321 return mounts_open_common(inode, file, show_vfsstat);
322 }
323
324 const struct file_operations proc_mounts_operations = {
325 .open = mounts_open,
326 .read_iter = seq_read_iter,
327 .splice_read = copy_splice_read,
328 .llseek = seq_lseek,
329 .release = mounts_release,
330 .poll = mounts_poll,
331 };
332
333 const struct file_operations proc_mountinfo_operations = {
334 .open = mountinfo_open,
335 .read_iter = seq_read_iter,
336 .splice_read = copy_splice_read,
337 .llseek = seq_lseek,
338 .release = mounts_release,
339 .poll = mounts_poll,
340 };
341
342 const struct file_operations proc_mountstats_operations = {
343 .open = mountstats_open,
344 .read_iter = seq_read_iter,
345 .splice_read = copy_splice_read,
346 .llseek = seq_lseek,
347 .release = mounts_release,
348 };
349