1 /*
2 * fs/proc_namespace.c - handling of /proc/<pid>/{mounts,mountinfo,mountstats}
3 *
4 * In fact, that's a piece of procfs; it's *almost* isolated from
5 * the rest of fs/proc, but has rather close relationships with
6 * fs/namespace.c, thus here instead of fs/proc
7 *
8 */
9 #include <linux/mnt_namespace.h>
10 #include <linux/nsproxy.h>
11 #include <linux/security.h>
12 #include <linux/fs_struct.h>
13 #include "proc/internal.h" /* only for get_proc_task() in ->open() */
14
15 #include "pnode.h"
16 #include "internal.h"
17
mounts_poll(struct file * file,poll_table * wait)18 static unsigned mounts_poll(struct file *file, poll_table *wait)
19 {
20 struct seq_file *m = file->private_data;
21 struct proc_mounts *p = m->private;
22 struct mnt_namespace *ns = p->ns;
23 unsigned res = POLLIN | POLLRDNORM;
24 int event;
25
26 poll_wait(file, &p->ns->poll, wait);
27
28 event = ACCESS_ONCE(ns->event);
29 if (m->poll_event != event) {
30 m->poll_event = event;
31 res |= POLLERR | POLLPRI;
32 }
33
34 return res;
35 }
36
37 struct proc_fs_info {
38 int flag;
39 const char *str;
40 };
41
show_sb_opts(struct seq_file * m,struct super_block * sb)42 static int show_sb_opts(struct seq_file *m, struct super_block *sb)
43 {
44 static const struct proc_fs_info fs_info[] = {
45 { MS_SYNCHRONOUS, ",sync" },
46 { MS_DIRSYNC, ",dirsync" },
47 { MS_MANDLOCK, ",mand" },
48 { MS_LAZYTIME, ",lazytime" },
49 { 0, NULL }
50 };
51 const struct proc_fs_info *fs_infop;
52
53 for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
54 if (sb->s_flags & fs_infop->flag)
55 seq_puts(m, fs_infop->str);
56 }
57
58 return security_sb_show_options(m, sb);
59 }
60
show_mnt_opts(struct seq_file * m,struct vfsmount * mnt)61 static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
62 {
63 static const struct proc_fs_info mnt_info[] = {
64 { MNT_NOSUID, ",nosuid" },
65 { MNT_NODEV, ",nodev" },
66 { MNT_NOEXEC, ",noexec" },
67 { MNT_NOATIME, ",noatime" },
68 { MNT_NODIRATIME, ",nodiratime" },
69 { MNT_RELATIME, ",relatime" },
70 { 0, NULL }
71 };
72 const struct proc_fs_info *fs_infop;
73
74 for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
75 if (mnt->mnt_flags & fs_infop->flag)
76 seq_puts(m, fs_infop->str);
77 }
78 }
79
mangle(struct seq_file * m,const char * s)80 static inline void mangle(struct seq_file *m, const char *s)
81 {
82 seq_escape(m, s, " \t\n\\");
83 }
84
show_type(struct seq_file * m,struct super_block * sb)85 static void show_type(struct seq_file *m, struct super_block *sb)
86 {
87 mangle(m, sb->s_type->name);
88 if (sb->s_subtype && sb->s_subtype[0]) {
89 seq_putc(m, '.');
90 mangle(m, sb->s_subtype);
91 }
92 }
93
show_vfsmnt(struct seq_file * m,struct vfsmount * mnt)94 static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)
95 {
96 struct proc_mounts *p = m->private;
97 struct mount *r = real_mount(mnt);
98 int err = 0;
99 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
100 struct super_block *sb = mnt_path.dentry->d_sb;
101
102 if (sb->s_op->show_devname) {
103 err = sb->s_op->show_devname(m, mnt_path.dentry);
104 if (err)
105 goto out;
106 } else {
107 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
108 }
109 seq_putc(m, ' ');
110 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
111 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
112 if (err)
113 goto out;
114 seq_putc(m, ' ');
115 show_type(m, sb);
116 seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
117 err = show_sb_opts(m, sb);
118 if (err)
119 goto out;
120 show_mnt_opts(m, mnt);
121 if (sb->s_op->show_options2)
122 err = sb->s_op->show_options2(mnt, m, mnt_path.dentry);
123 else if (sb->s_op->show_options)
124 err = sb->s_op->show_options(m, mnt_path.dentry);
125 seq_puts(m, " 0 0\n");
126 out:
127 return err;
128 }
129
show_mountinfo(struct seq_file * m,struct vfsmount * mnt)130 static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
131 {
132 struct proc_mounts *p = m->private;
133 struct mount *r = real_mount(mnt);
134 struct super_block *sb = mnt->mnt_sb;
135 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
136 int err = 0;
137
138 seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id,
139 MAJOR(sb->s_dev), MINOR(sb->s_dev));
140 if (sb->s_op->show_path)
141 err = sb->s_op->show_path(m, mnt->mnt_root);
142 else
143 seq_dentry(m, mnt->mnt_root, " \t\n\\");
144 if (err)
145 goto out;
146 seq_putc(m, ' ');
147
148 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
149 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
150 if (err)
151 goto out;
152
153 seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
154 show_mnt_opts(m, mnt);
155
156 /* Tagged fields ("foo:X" or "bar") */
157 if (IS_MNT_SHARED(r))
158 seq_printf(m, " shared:%i", r->mnt_group_id);
159 if (IS_MNT_SLAVE(r)) {
160 int master = r->mnt_master->mnt_group_id;
161 int dom = get_dominating_id(r, &p->root);
162 seq_printf(m, " master:%i", master);
163 if (dom && dom != master)
164 seq_printf(m, " propagate_from:%i", dom);
165 }
166 if (IS_MNT_UNBINDABLE(r))
167 seq_puts(m, " unbindable");
168
169 /* Filesystem specific data */
170 seq_puts(m, " - ");
171 show_type(m, sb);
172 seq_putc(m, ' ');
173 if (sb->s_op->show_devname)
174 err = sb->s_op->show_devname(m, mnt->mnt_root);
175 else
176 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
177 if (err)
178 goto out;
179 seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw");
180 err = show_sb_opts(m, sb);
181 if (err)
182 goto out;
183 if (sb->s_op->show_options2) {
184 err = sb->s_op->show_options2(mnt, m, mnt->mnt_root);
185 } else if (sb->s_op->show_options)
186 err = sb->s_op->show_options(m, mnt->mnt_root);
187 seq_putc(m, '\n');
188 out:
189 return err;
190 }
191
show_vfsstat(struct seq_file * m,struct vfsmount * mnt)192 static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt)
193 {
194 struct proc_mounts *p = m->private;
195 struct mount *r = real_mount(mnt);
196 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
197 struct super_block *sb = mnt_path.dentry->d_sb;
198 int err = 0;
199
200 /* device */
201 if (sb->s_op->show_devname) {
202 seq_puts(m, "device ");
203 err = sb->s_op->show_devname(m, mnt_path.dentry);
204 if (err)
205 goto out;
206 } else {
207 if (r->mnt_devname) {
208 seq_puts(m, "device ");
209 mangle(m, r->mnt_devname);
210 } else
211 seq_puts(m, "no device");
212 }
213
214 /* mount point */
215 seq_puts(m, " mounted on ");
216 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
217 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
218 if (err)
219 goto out;
220 seq_putc(m, ' ');
221
222 /* file system type */
223 seq_puts(m, "with fstype ");
224 show_type(m, sb);
225
226 /* optional statistics */
227 if (sb->s_op->show_stats) {
228 seq_putc(m, ' ');
229 if (!err)
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