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 proc_mounts *p = proc_mounts(file->private_data);
21 struct mnt_namespace *ns = p->ns;
22 unsigned res = POLLIN | POLLRDNORM;
23
24 poll_wait(file, &p->ns->poll, wait);
25
26 br_read_lock(&vfsmount_lock);
27 if (p->m.poll_event != ns->event) {
28 p->m.poll_event = ns->event;
29 res |= POLLERR | POLLPRI;
30 }
31 br_read_unlock(&vfsmount_lock);
32
33 return res;
34 }
35
36 struct proc_fs_info {
37 int flag;
38 const char *str;
39 };
40
show_sb_opts(struct seq_file * m,struct super_block * sb)41 static int show_sb_opts(struct seq_file *m, struct super_block *sb)
42 {
43 static const struct proc_fs_info fs_info[] = {
44 { MS_SYNCHRONOUS, ",sync" },
45 { MS_DIRSYNC, ",dirsync" },
46 { MS_MANDLOCK, ",mand" },
47 { 0, NULL }
48 };
49 const struct proc_fs_info *fs_infop;
50
51 for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
52 if (sb->s_flags & fs_infop->flag)
53 seq_puts(m, fs_infop->str);
54 }
55
56 return security_sb_show_options(m, sb);
57 }
58
show_mnt_opts(struct seq_file * m,struct vfsmount * mnt)59 static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
60 {
61 static const struct proc_fs_info mnt_info[] = {
62 { MNT_NOSUID, ",nosuid" },
63 { MNT_NODEV, ",nodev" },
64 { MNT_NOEXEC, ",noexec" },
65 { MNT_NOATIME, ",noatime" },
66 { MNT_NODIRATIME, ",nodiratime" },
67 { MNT_RELATIME, ",relatime" },
68 { 0, NULL }
69 };
70 const struct proc_fs_info *fs_infop;
71
72 for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
73 if (mnt->mnt_flags & fs_infop->flag)
74 seq_puts(m, fs_infop->str);
75 }
76 }
77
mangle(struct seq_file * m,const char * s)78 static inline void mangle(struct seq_file *m, const char *s)
79 {
80 seq_escape(m, s, " \t\n\\");
81 }
82
show_type(struct seq_file * m,struct super_block * sb)83 static void show_type(struct seq_file *m, struct super_block *sb)
84 {
85 mangle(m, sb->s_type->name);
86 if (sb->s_subtype && sb->s_subtype[0]) {
87 seq_putc(m, '.');
88 mangle(m, sb->s_subtype);
89 }
90 }
91
show_vfsmnt(struct seq_file * m,struct vfsmount * mnt)92 static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)
93 {
94 struct mount *r = real_mount(mnt);
95 int err = 0;
96 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
97 struct super_block *sb = mnt_path.dentry->d_sb;
98
99 if (sb->s_op->show_devname) {
100 err = sb->s_op->show_devname(m, mnt_path.dentry);
101 if (err)
102 goto out;
103 } else {
104 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
105 }
106 seq_putc(m, ' ');
107 seq_path(m, &mnt_path, " \t\n\\");
108 seq_putc(m, ' ');
109 show_type(m, sb);
110 seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
111 err = show_sb_opts(m, sb);
112 if (err)
113 goto out;
114 show_mnt_opts(m, mnt);
115 if (sb->s_op->show_options2)
116 err = sb->s_op->show_options2(mnt, m, mnt_path.dentry);
117 else if (sb->s_op->show_options)
118 err = sb->s_op->show_options(m, mnt_path.dentry);
119 seq_puts(m, " 0 0\n");
120 out:
121 return err;
122 }
123
show_mountinfo(struct seq_file * m,struct vfsmount * mnt)124 static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
125 {
126 struct proc_mounts *p = proc_mounts(m);
127 struct mount *r = real_mount(mnt);
128 struct super_block *sb = mnt->mnt_sb;
129 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
130 struct path root = p->root;
131 int err = 0;
132
133 seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id,
134 MAJOR(sb->s_dev), MINOR(sb->s_dev));
135 if (sb->s_op->show_path)
136 err = sb->s_op->show_path(m, mnt->mnt_root);
137 else
138 seq_dentry(m, mnt->mnt_root, " \t\n\\");
139 if (err)
140 goto out;
141 seq_putc(m, ' ');
142
143 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
144 err = seq_path_root(m, &mnt_path, &root, " \t\n\\");
145 if (err)
146 goto out;
147
148 seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
149 show_mnt_opts(m, mnt);
150
151 /* Tagged fields ("foo:X" or "bar") */
152 if (IS_MNT_SHARED(r))
153 seq_printf(m, " shared:%i", r->mnt_group_id);
154 if (IS_MNT_SLAVE(r)) {
155 int master = r->mnt_master->mnt_group_id;
156 int dom = get_dominating_id(r, &p->root);
157 seq_printf(m, " master:%i", master);
158 if (dom && dom != master)
159 seq_printf(m, " propagate_from:%i", dom);
160 }
161 if (IS_MNT_UNBINDABLE(r))
162 seq_puts(m, " unbindable");
163
164 /* Filesystem specific data */
165 seq_puts(m, " - ");
166 show_type(m, sb);
167 seq_putc(m, ' ');
168 if (sb->s_op->show_devname)
169 err = sb->s_op->show_devname(m, mnt->mnt_root);
170 else
171 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
172 if (err)
173 goto out;
174 seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw");
175 err = show_sb_opts(m, sb);
176 if (err)
177 goto out;
178 if (sb->s_op->show_options2) {
179 err = sb->s_op->show_options2(mnt, m, mnt->mnt_root);
180 } else if (sb->s_op->show_options)
181 err = sb->s_op->show_options(m, mnt->mnt_root);
182 seq_putc(m, '\n');
183 out:
184 return err;
185 }
186
show_vfsstat(struct seq_file * m,struct vfsmount * mnt)187 static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt)
188 {
189 struct mount *r = real_mount(mnt);
190 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
191 struct super_block *sb = mnt_path.dentry->d_sb;
192 int err = 0;
193
194 /* device */
195 if (sb->s_op->show_devname) {
196 seq_puts(m, "device ");
197 err = sb->s_op->show_devname(m, mnt_path.dentry);
198 } else {
199 if (r->mnt_devname) {
200 seq_puts(m, "device ");
201 mangle(m, r->mnt_devname);
202 } else
203 seq_puts(m, "no device");
204 }
205
206 /* mount point */
207 seq_puts(m, " mounted on ");
208 seq_path(m, &mnt_path, " \t\n\\");
209 seq_putc(m, ' ');
210
211 /* file system type */
212 seq_puts(m, "with fstype ");
213 show_type(m, sb);
214
215 /* optional statistics */
216 if (sb->s_op->show_stats) {
217 seq_putc(m, ' ');
218 if (!err)
219 err = sb->s_op->show_stats(m, mnt_path.dentry);
220 }
221
222 seq_putc(m, '\n');
223 return err;
224 }
225
mounts_open_common(struct inode * inode,struct file * file,int (* show)(struct seq_file *,struct vfsmount *))226 static int mounts_open_common(struct inode *inode, struct file *file,
227 int (*show)(struct seq_file *, struct vfsmount *))
228 {
229 struct task_struct *task = get_proc_task(inode);
230 struct nsproxy *nsp;
231 struct mnt_namespace *ns = NULL;
232 struct path root;
233 struct proc_mounts *p;
234 int ret = -EINVAL;
235
236 if (!task)
237 goto err;
238
239 rcu_read_lock();
240 nsp = task_nsproxy(task);
241 if (!nsp) {
242 rcu_read_unlock();
243 put_task_struct(task);
244 goto err;
245 }
246 ns = nsp->mnt_ns;
247 if (!ns) {
248 rcu_read_unlock();
249 put_task_struct(task);
250 goto err;
251 }
252 get_mnt_ns(ns);
253 rcu_read_unlock();
254 task_lock(task);
255 if (!task->fs) {
256 task_unlock(task);
257 put_task_struct(task);
258 ret = -ENOENT;
259 goto err_put_ns;
260 }
261 get_fs_root(task->fs, &root);
262 task_unlock(task);
263 put_task_struct(task);
264
265 ret = -ENOMEM;
266 p = kmalloc(sizeof(struct proc_mounts), GFP_KERNEL);
267 if (!p)
268 goto err_put_path;
269
270 file->private_data = &p->m;
271 ret = seq_open(file, &mounts_op);
272 if (ret)
273 goto err_free;
274
275 p->ns = ns;
276 p->root = root;
277 p->m.poll_event = ns->event;
278 p->show = show;
279
280 return 0;
281
282 err_free:
283 kfree(p);
284 err_put_path:
285 path_put(&root);
286 err_put_ns:
287 put_mnt_ns(ns);
288 err:
289 return ret;
290 }
291
mounts_release(struct inode * inode,struct file * file)292 static int mounts_release(struct inode *inode, struct file *file)
293 {
294 struct proc_mounts *p = proc_mounts(file->private_data);
295 path_put(&p->root);
296 put_mnt_ns(p->ns);
297 return seq_release(inode, file);
298 }
299
mounts_open(struct inode * inode,struct file * file)300 static int mounts_open(struct inode *inode, struct file *file)
301 {
302 return mounts_open_common(inode, file, show_vfsmnt);
303 }
304
mountinfo_open(struct inode * inode,struct file * file)305 static int mountinfo_open(struct inode *inode, struct file *file)
306 {
307 return mounts_open_common(inode, file, show_mountinfo);
308 }
309
mountstats_open(struct inode * inode,struct file * file)310 static int mountstats_open(struct inode *inode, struct file *file)
311 {
312 return mounts_open_common(inode, file, show_vfsstat);
313 }
314
315 const struct file_operations proc_mounts_operations = {
316 .open = mounts_open,
317 .read = seq_read,
318 .llseek = seq_lseek,
319 .release = mounts_release,
320 .poll = mounts_poll,
321 };
322
323 const struct file_operations proc_mountinfo_operations = {
324 .open = mountinfo_open,
325 .read = seq_read,
326 .llseek = seq_lseek,
327 .release = mounts_release,
328 .poll = mounts_poll,
329 };
330
331 const struct file_operations proc_mountstats_operations = {
332 .open = mountstats_open,
333 .read = seq_read,
334 .llseek = seq_lseek,
335 .release = mounts_release,
336 };
337