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_options)
125 err = sb->s_op->show_options(m, mnt_path.dentry);
126 seq_puts(m, " 0 0\n");
127 out:
128 return err;
129 }
130
show_mountinfo(struct seq_file * m,struct vfsmount * mnt)131 static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
132 {
133 struct proc_mounts *p = m->private;
134 struct mount *r = real_mount(mnt);
135 struct super_block *sb = mnt->mnt_sb;
136 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
137 int err;
138
139 seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id,
140 MAJOR(sb->s_dev), MINOR(sb->s_dev));
141 if (sb->s_op->show_path) {
142 err = sb->s_op->show_path(m, mnt->mnt_root);
143 if (err)
144 goto out;
145 } else {
146 seq_dentry(m, mnt->mnt_root, " \t\n\\");
147 }
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_mnt_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 ? r->mnt_devname : "none");
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');
189 out:
190 return err;
191 }
192
show_vfsstat(struct seq_file * m,struct vfsmount * mnt)193 static 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 if (sb->s_op->show_devname) {
203 seq_puts(m, "device ");
204 err = sb->s_op->show_devname(m, mnt_path.dentry);
205 if (err)
206 goto out;
207 } else {
208 if (r->mnt_devname) {
209 seq_puts(m, "device ");
210 mangle(m, r->mnt_devname);
211 } else
212 seq_puts(m, "no device");
213 }
214
215 /* mount point */
216 seq_puts(m, " mounted on ");
217 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
218 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
219 if (err)
220 goto out;
221 seq_putc(m, ' ');
222
223 /* file system type */
224 seq_puts(m, "with fstype ");
225 show_type(m, sb);
226
227 /* optional statistics */
228 if (sb->s_op->show_stats) {
229 seq_putc(m, ' ');
230 err = sb->s_op->show_stats(m, mnt_path.dentry);
231 }
232
233 seq_putc(m, '\n');
234 out:
235 return err;
236 }
237
mounts_open_common(struct inode * inode,struct file * file,int (* show)(struct seq_file *,struct vfsmount *))238 static int mounts_open_common(struct inode *inode, struct file *file,
239 int (*show)(struct seq_file *, struct vfsmount *))
240 {
241 struct task_struct *task = get_proc_task(inode);
242 struct nsproxy *nsp;
243 struct mnt_namespace *ns = NULL;
244 struct path root;
245 struct proc_mounts *p;
246 struct seq_file *m;
247 int ret = -EINVAL;
248
249 if (!task)
250 goto err;
251
252 task_lock(task);
253 nsp = task->nsproxy;
254 if (!nsp || !nsp->mnt_ns) {
255 task_unlock(task);
256 put_task_struct(task);
257 goto err;
258 }
259 ns = nsp->mnt_ns;
260 get_mnt_ns(ns);
261 if (!task->fs) {
262 task_unlock(task);
263 put_task_struct(task);
264 ret = -ENOENT;
265 goto err_put_ns;
266 }
267 get_fs_root(task->fs, &root);
268 task_unlock(task);
269 put_task_struct(task);
270
271 ret = seq_open_private(file, &mounts_op, sizeof(struct proc_mounts));
272 if (ret)
273 goto err_put_path;
274
275 m = file->private_data;
276 m->poll_event = ns->event;
277
278 p = m->private;
279 p->ns = ns;
280 p->root = root;
281 p->show = show;
282 p->cached_event = ~0ULL;
283
284 return 0;
285
286 err_put_path:
287 path_put(&root);
288 err_put_ns:
289 put_mnt_ns(ns);
290 err:
291 return ret;
292 }
293
mounts_release(struct inode * inode,struct file * file)294 static int mounts_release(struct inode *inode, struct file *file)
295 {
296 struct seq_file *m = file->private_data;
297 struct proc_mounts *p = m->private;
298 path_put(&p->root);
299 put_mnt_ns(p->ns);
300 return seq_release_private(inode, file);
301 }
302
mounts_open(struct inode * inode,struct file * file)303 static int mounts_open(struct inode *inode, struct file *file)
304 {
305 return mounts_open_common(inode, file, show_vfsmnt);
306 }
307
mountinfo_open(struct inode * inode,struct file * file)308 static int mountinfo_open(struct inode *inode, struct file *file)
309 {
310 return mounts_open_common(inode, file, show_mountinfo);
311 }
312
mountstats_open(struct inode * inode,struct file * file)313 static int mountstats_open(struct inode *inode, struct file *file)
314 {
315 return mounts_open_common(inode, file, show_vfsstat);
316 }
317
318 const struct file_operations proc_mounts_operations = {
319 .open = mounts_open,
320 .read = seq_read,
321 .llseek = seq_lseek,
322 .release = mounts_release,
323 .poll = mounts_poll,
324 };
325
326 const struct file_operations proc_mountinfo_operations = {
327 .open = mountinfo_open,
328 .read = seq_read,
329 .llseek = seq_lseek,
330 .release = mounts_release,
331 .poll = mounts_poll,
332 };
333
334 const struct file_operations proc_mountstats_operations = {
335 .open = mountstats_open,
336 .read = seq_read,
337 .llseek = seq_lseek,
338 .release = mounts_release,
339 };
340
