Line data Source code
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 :
21 0 : static __poll_t mounts_poll(struct file *file, poll_table *wait)
22 : {
23 0 : struct seq_file *m = file->private_data;
24 0 : struct proc_mounts *p = m->private;
25 0 : struct mnt_namespace *ns = p->ns;
26 0 : __poll_t res = EPOLLIN | EPOLLRDNORM;
27 : int event;
28 :
29 0 : poll_wait(file, &p->ns->poll, wait);
30 :
31 0 : event = READ_ONCE(ns->event);
32 0 : if (m->poll_event != event) {
33 0 : m->poll_event = event;
34 0 : res |= EPOLLERR | EPOLLPRI;
35 : }
36 :
37 0 : return res;
38 : }
39 :
40 : struct proc_fs_opts {
41 : int flag;
42 : const char *str;
43 : };
44 :
45 0 : 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 0 : for (fs_infop = fs_opts; fs_infop->flag; fs_infop++) {
57 0 : if (sb->s_flags & fs_infop->flag)
58 0 : seq_puts(m, fs_infop->str);
59 : }
60 :
61 0 : return security_sb_show_options(m, sb);
62 : }
63 :
64 0 : 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 0 : for (fs_infop = mnt_opts; fs_infop->flag; fs_infop++) {
79 0 : if (mnt->mnt_flags & fs_infop->flag)
80 0 : seq_puts(m, fs_infop->str);
81 : }
82 :
83 0 : if (is_idmapped_mnt(mnt))
84 0 : seq_puts(m, ",idmapped");
85 0 : }
86 :
87 : static inline void mangle(struct seq_file *m, const char *s)
88 : {
89 0 : seq_escape(m, s, " \t\n\\#");
90 : }
91 :
92 0 : static void show_type(struct seq_file *m, struct super_block *sb)
93 : {
94 0 : mangle(m, sb->s_type->name);
95 0 : if (sb->s_subtype) {
96 0 : seq_putc(m, '.');
97 0 : mangle(m, sb->s_subtype);
98 : }
99 0 : }
100 :
101 0 : static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)
102 : {
103 0 : struct proc_mounts *p = m->private;
104 0 : struct mount *r = real_mount(mnt);
105 0 : struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
106 0 : struct super_block *sb = mnt_path.dentry->d_sb;
107 : int err;
108 :
109 0 : if (sb->s_op->show_devname) {
110 0 : err = sb->s_op->show_devname(m, mnt_path.dentry);
111 0 : if (err)
112 : goto out;
113 : } else {
114 0 : mangle(m, r->mnt_devname ? r->mnt_devname : "none");
115 : }
116 0 : seq_putc(m, ' ');
117 : /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
118 0 : err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
119 0 : if (err)
120 : goto out;
121 0 : seq_putc(m, ' ');
122 0 : show_type(m, sb);
123 0 : seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
124 0 : err = show_sb_opts(m, sb);
125 0 : if (err)
126 : goto out;
127 0 : show_mnt_opts(m, mnt);
128 0 : if (sb->s_op->show_options)
129 0 : err = sb->s_op->show_options(m, mnt_path.dentry);
130 0 : seq_puts(m, " 0 0\n");
131 : out:
132 0 : return err;
133 : }
134 :
135 0 : static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
136 : {
137 0 : struct proc_mounts *p = m->private;
138 0 : struct mount *r = real_mount(mnt);
139 0 : struct super_block *sb = mnt->mnt_sb;
140 0 : struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
141 : int err;
142 :
143 0 : seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id,
144 0 : MAJOR(sb->s_dev), MINOR(sb->s_dev));
145 0 : if (sb->s_op->show_path) {
146 0 : err = sb->s_op->show_path(m, mnt->mnt_root);
147 0 : if (err)
148 : goto out;
149 : } else {
150 0 : seq_dentry(m, mnt->mnt_root, " \t\n\\");
151 : }
152 0 : seq_putc(m, ' ');
153 :
154 : /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
155 0 : err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
156 0 : if (err)
157 : goto out;
158 :
159 0 : seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
160 0 : show_mnt_opts(m, mnt);
161 :
162 : /* Tagged fields ("foo:X" or "bar") */
163 0 : if (IS_MNT_SHARED(r))
164 0 : seq_printf(m, " shared:%i", r->mnt_group_id);
165 0 : if (IS_MNT_SLAVE(r)) {
166 0 : int master = r->mnt_master->mnt_group_id;
167 0 : int dom = get_dominating_id(r, &p->root);
168 0 : seq_printf(m, " master:%i", master);
169 0 : if (dom && dom != master)
170 0 : seq_printf(m, " propagate_from:%i", dom);
171 : }
172 0 : if (IS_MNT_UNBINDABLE(r))
173 0 : seq_puts(m, " unbindable");
174 :
175 : /* Filesystem specific data */
176 0 : seq_puts(m, " - ");
177 0 : show_type(m, sb);
178 0 : seq_putc(m, ' ');
179 0 : if (sb->s_op->show_devname) {
180 0 : err = sb->s_op->show_devname(m, mnt->mnt_root);
181 0 : if (err)
182 : goto out;
183 : } else {
184 0 : mangle(m, r->mnt_devname ? r->mnt_devname : "none");
185 : }
186 0 : seq_puts(m, sb_rdonly(sb) ? " ro" : " rw");
187 0 : err = show_sb_opts(m, sb);
188 0 : if (err)
189 : goto out;
190 0 : if (sb->s_op->show_options)
191 0 : err = sb->s_op->show_options(m, mnt->mnt_root);
192 0 : seq_putc(m, '\n');
193 : out:
194 0 : return err;
195 : }
196 :
197 0 : static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt)
198 : {
199 0 : struct proc_mounts *p = m->private;
200 0 : struct mount *r = real_mount(mnt);
201 0 : struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
202 0 : struct super_block *sb = mnt_path.dentry->d_sb;
203 : int err;
204 :
205 : /* device */
206 0 : if (sb->s_op->show_devname) {
207 0 : seq_puts(m, "device ");
208 0 : err = sb->s_op->show_devname(m, mnt_path.dentry);
209 0 : if (err)
210 : goto out;
211 : } else {
212 0 : if (r->mnt_devname) {
213 0 : seq_puts(m, "device ");
214 0 : mangle(m, r->mnt_devname);
215 : } else
216 0 : seq_puts(m, "no device");
217 : }
218 :
219 : /* mount point */
220 0 : seq_puts(m, " mounted on ");
221 : /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
222 0 : err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
223 0 : if (err)
224 : goto out;
225 0 : seq_putc(m, ' ');
226 :
227 : /* file system type */
228 0 : seq_puts(m, "with fstype ");
229 0 : show_type(m, sb);
230 :
231 : /* optional statistics */
232 0 : if (sb->s_op->show_stats) {
233 0 : seq_putc(m, ' ');
234 0 : err = sb->s_op->show_stats(m, mnt_path.dentry);
235 : }
236 :
237 0 : seq_putc(m, '\n');
238 : out:
239 0 : return err;
240 : }
241 :
242 0 : static int mounts_open_common(struct inode *inode, struct file *file,
243 : int (*show)(struct seq_file *, struct vfsmount *))
244 : {
245 0 : struct task_struct *task = get_proc_task(inode);
246 : struct nsproxy *nsp;
247 0 : struct mnt_namespace *ns = NULL;
248 : struct path root;
249 : struct proc_mounts *p;
250 : struct seq_file *m;
251 0 : int ret = -EINVAL;
252 :
253 0 : if (!task)
254 : goto err;
255 :
256 : task_lock(task);
257 0 : nsp = task->nsproxy;
258 0 : if (!nsp || !nsp->mnt_ns) {
259 : task_unlock(task);
260 0 : put_task_struct(task);
261 0 : goto err;
262 : }
263 0 : ns = nsp->mnt_ns;
264 0 : get_mnt_ns(ns);
265 0 : if (!task->fs) {
266 : task_unlock(task);
267 0 : put_task_struct(task);
268 0 : ret = -ENOENT;
269 0 : goto err_put_ns;
270 : }
271 0 : get_fs_root(task->fs, &root);
272 : task_unlock(task);
273 0 : put_task_struct(task);
274 :
275 0 : ret = seq_open_private(file, &mounts_op, sizeof(struct proc_mounts));
276 0 : if (ret)
277 : goto err_put_path;
278 :
279 0 : m = file->private_data;
280 0 : m->poll_event = ns->event;
281 :
282 0 : p = m->private;
283 0 : p->ns = ns;
284 0 : p->root = root;
285 0 : p->show = show;
286 0 : INIT_LIST_HEAD(&p->cursor.mnt_list);
287 0 : p->cursor.mnt.mnt_flags = MNT_CURSOR;
288 :
289 0 : return 0;
290 :
291 : err_put_path:
292 0 : path_put(&root);
293 : err_put_ns:
294 0 : put_mnt_ns(ns);
295 : err:
296 : return ret;
297 : }
298 :
299 0 : static int mounts_release(struct inode *inode, struct file *file)
300 : {
301 0 : struct seq_file *m = file->private_data;
302 0 : struct proc_mounts *p = m->private;
303 0 : path_put(&p->root);
304 0 : mnt_cursor_del(p->ns, &p->cursor);
305 0 : put_mnt_ns(p->ns);
306 0 : return seq_release_private(inode, file);
307 : }
308 :
309 0 : static int mounts_open(struct inode *inode, struct file *file)
310 : {
311 0 : return mounts_open_common(inode, file, show_vfsmnt);
312 : }
313 :
314 0 : static int mountinfo_open(struct inode *inode, struct file *file)
315 : {
316 0 : return mounts_open_common(inode, file, show_mountinfo);
317 : }
318 :
319 0 : static int mountstats_open(struct inode *inode, struct file *file)
320 : {
321 0 : 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 = generic_file_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 = generic_file_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 = generic_file_splice_read,
346 : .llseek = seq_lseek,
347 : .release = mounts_release,
348 : };
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