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 | 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(filp: file, wait_address: &p->ns->poll, p: 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 | |
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, s: fs_infop->str); |
59 | } |
60 | |
61 | return security_sb_show_options(m, sb); |
62 | } |
63 | |
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, s: fs_infop->str); |
81 | } |
82 | |
83 | if (is_idmapped_mnt(mnt)) |
84 | seq_puts(m, s: ",idmapped" ); |
85 | } |
86 | |
87 | static inline void mangle(struct seq_file *m, const char *s) |
88 | { |
89 | seq_escape(m, s, esc: " \t\n\\#" ); |
90 | } |
91 | |
92 | static void show_type(struct seq_file *m, struct super_block *sb) |
93 | { |
94 | mangle(m, s: sb->s_type->name); |
95 | if (sb->s_subtype) { |
96 | seq_putc(m, c: '.'); |
97 | mangle(m, s: sb->s_subtype); |
98 | } |
99 | } |
100 | |
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, s: r->mnt_devname ? r->mnt_devname : "none" ); |
115 | } |
116 | seq_putc(m, c: ' '); |
117 | /* mountpoints outside of chroot jail will give SEQ_SKIP on this */ |
118 | err = seq_path_root(m, path: &mnt_path, root: &p->root, esc: " \t\n\\" ); |
119 | if (err) |
120 | goto out; |
121 | seq_putc(m, c: ' '); |
122 | show_type(m, sb); |
123 | seq_puts(m, s: __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, s: " 0 0\n" ); |
131 | out: |
132 | return err; |
133 | } |
134 | |
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, fmt: "%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, c: ' '); |
153 | |
154 | /* mountpoints outside of chroot jail will give SEQ_SKIP on this */ |
155 | err = seq_path_root(m, path: &mnt_path, root: &p->root, esc: " \t\n\\" ); |
156 | if (err) |
157 | goto out; |
158 | |
159 | seq_puts(m, s: 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, fmt: " 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(mnt: r, root: &p->root); |
168 | seq_printf(m, fmt: " master:%i" , master); |
169 | if (dom && dom != master) |
170 | seq_printf(m, fmt: " propagate_from:%i" , dom); |
171 | } |
172 | if (IS_MNT_UNBINDABLE(r)) |
173 | seq_puts(m, s: " unbindable" ); |
174 | |
175 | /* Filesystem specific data */ |
176 | seq_puts(m, s: " - " ); |
177 | show_type(m, sb); |
178 | seq_putc(m, c: ' '); |
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, s: r->mnt_devname ? r->mnt_devname : "none" ); |
185 | } |
186 | seq_puts(m, s: 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, c: '\n'); |
193 | out: |
194 | return err; |
195 | } |
196 | |
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, s: "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, s: "device " ); |
214 | mangle(m, s: r->mnt_devname); |
215 | } else |
216 | seq_puts(m, s: "no device" ); |
217 | } |
218 | |
219 | /* mount point */ |
220 | seq_puts(m, s: " mounted on " ); |
221 | /* mountpoints outside of chroot jail will give SEQ_SKIP on this */ |
222 | err = seq_path_root(m, path: &mnt_path, root: &p->root, esc: " \t\n\\" ); |
223 | if (err) |
224 | goto out; |
225 | seq_putc(m, c: ' '); |
226 | |
227 | /* file system type */ |
228 | seq_puts(m, s: "with fstype " ); |
229 | show_type(m, sb); |
230 | |
231 | /* optional statistics */ |
232 | if (sb->s_op->show_stats) { |
233 | seq_putc(m, c: ' '); |
234 | err = sb->s_op->show_stats(m, mnt_path.dentry); |
235 | } |
236 | |
237 | seq_putc(m, c: '\n'); |
238 | out: |
239 | return err; |
240 | } |
241 | |
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(p: task); |
257 | nsp = task->nsproxy; |
258 | if (!nsp || !nsp->mnt_ns) { |
259 | task_unlock(p: task); |
260 | put_task_struct(t: task); |
261 | goto err; |
262 | } |
263 | ns = nsp->mnt_ns; |
264 | get_mnt_ns(ns); |
265 | if (!task->fs) { |
266 | task_unlock(p: task); |
267 | put_task_struct(t: task); |
268 | ret = -ENOENT; |
269 | goto err_put_ns; |
270 | } |
271 | get_fs_root(fs: task->fs, root: &root); |
272 | task_unlock(p: task); |
273 | put_task_struct(t: 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(list: &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 | |
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(ns: p->ns, cursor: &p->cursor); |
305 | put_mnt_ns(ns: p->ns); |
306 | return seq_release_private(inode, file); |
307 | } |
308 | |
309 | static int mounts_open(struct inode *inode, struct file *file) |
310 | { |
311 | return mounts_open_common(inode, file, show: show_vfsmnt); |
312 | } |
313 | |
314 | static int mountinfo_open(struct inode *inode, struct file *file) |
315 | { |
316 | return mounts_open_common(inode, file, show: show_mountinfo); |
317 | } |
318 | |
319 | static int mountstats_open(struct inode *inode, struct file *file) |
320 | { |
321 | return mounts_open_common(inode, file, show: 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 | |