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
18static 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
37struct proc_fs_info {
38	int flag;
39	const char *str;
40};
41
42static 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
61static 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
80static inline void mangle(struct seq_file *m, const char *s)
81{
82	seq_escape(m, s, " \t\n\\");
83}
84
85static 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
94static 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_options)
122		err = sb->s_op->show_options(m, mnt_path.dentry);
123	seq_puts(m, " 0 0\n");
124out:
125	return err;
126}
127
128static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
129{
130	struct proc_mounts *p = m->private;
131	struct mount *r = real_mount(mnt);
132	struct super_block *sb = mnt->mnt_sb;
133	struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
134	int err = 0;
135
136	seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id,
137		   MAJOR(sb->s_dev), MINOR(sb->s_dev));
138	if (sb->s_op->show_path)
139		err = sb->s_op->show_path(m, mnt->mnt_root);
140	else
141		seq_dentry(m, mnt->mnt_root, " \t\n\\");
142	if (err)
143		goto out;
144	seq_putc(m, ' ');
145
146	/* mountpoints outside of chroot jail will give SEQ_SKIP on this */
147	err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
148	if (err)
149		goto out;
150
151	seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
152	show_mnt_opts(m, mnt);
153
154	/* Tagged fields ("foo:X" or "bar") */
155	if (IS_MNT_SHARED(r))
156		seq_printf(m, " shared:%i", r->mnt_group_id);
157	if (IS_MNT_SLAVE(r)) {
158		int master = r->mnt_master->mnt_group_id;
159		int dom = get_dominating_id(r, &p->root);
160		seq_printf(m, " master:%i", master);
161		if (dom && dom != master)
162			seq_printf(m, " propagate_from:%i", dom);
163	}
164	if (IS_MNT_UNBINDABLE(r))
165		seq_puts(m, " unbindable");
166
167	/* Filesystem specific data */
168	seq_puts(m, " - ");
169	show_type(m, sb);
170	seq_putc(m, ' ');
171	if (sb->s_op->show_devname)
172		err = sb->s_op->show_devname(m, mnt->mnt_root);
173	else
174		mangle(m, r->mnt_devname ? r->mnt_devname : "none");
175	if (err)
176		goto out;
177	seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw");
178	err = show_sb_opts(m, sb);
179	if (err)
180		goto out;
181	if (sb->s_op->show_options)
182		err = sb->s_op->show_options(m, mnt->mnt_root);
183	seq_putc(m, '\n');
184out:
185	return err;
186}
187
188static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt)
189{
190	struct proc_mounts *p = m->private;
191	struct mount *r = real_mount(mnt);
192	struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
193	struct super_block *sb = mnt_path.dentry->d_sb;
194	int err = 0;
195
196	/* device */
197	if (sb->s_op->show_devname) {
198		seq_puts(m, "device ");
199		err = sb->s_op->show_devname(m, mnt_path.dentry);
200		if (err)
201			goto out;
202	} else {
203		if (r->mnt_devname) {
204			seq_puts(m, "device ");
205			mangle(m, r->mnt_devname);
206		} else
207			seq_puts(m, "no device");
208	}
209
210	/* mount point */
211	seq_puts(m, " mounted on ");
212	/* mountpoints outside of chroot jail will give SEQ_SKIP on this */
213	err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
214	if (err)
215		goto out;
216	seq_putc(m, ' ');
217
218	/* file system type */
219	seq_puts(m, "with fstype ");
220	show_type(m, sb);
221
222	/* optional statistics */
223	if (sb->s_op->show_stats) {
224		seq_putc(m, ' ');
225		if (!err)
226			err = sb->s_op->show_stats(m, mnt_path.dentry);
227	}
228
229	seq_putc(m, '\n');
230out:
231	return err;
232}
233
234static int mounts_open_common(struct inode *inode, struct file *file,
235			      int (*show)(struct seq_file *, struct vfsmount *))
236{
237	struct task_struct *task = get_proc_task(inode);
238	struct nsproxy *nsp;
239	struct mnt_namespace *ns = NULL;
240	struct path root;
241	struct proc_mounts *p;
242	struct seq_file *m;
243	int ret = -EINVAL;
244
245	if (!task)
246		goto err;
247
248	task_lock(task);
249	nsp = task->nsproxy;
250	if (!nsp || !nsp->mnt_ns) {
251		task_unlock(task);
252		put_task_struct(task);
253		goto err;
254	}
255	ns = nsp->mnt_ns;
256	get_mnt_ns(ns);
257	if (!task->fs) {
258		task_unlock(task);
259		put_task_struct(task);
260		ret = -ENOENT;
261		goto err_put_ns;
262	}
263	get_fs_root(task->fs, &root);
264	task_unlock(task);
265	put_task_struct(task);
266
267	ret = seq_open_private(file, &mounts_op, sizeof(struct proc_mounts));
268	if (ret)
269		goto err_put_path;
270
271	m = file->private_data;
272	m->poll_event = ns->event;
273
274	p = m->private;
275	p->ns = ns;
276	p->root = root;
277	p->show = show;
278	p->cached_event = ~0ULL;
279
280	return 0;
281
282 err_put_path:
283	path_put(&root);
284 err_put_ns:
285	put_mnt_ns(ns);
286 err:
287	return ret;
288}
289
290static int mounts_release(struct inode *inode, struct file *file)
291{
292	struct seq_file *m = file->private_data;
293	struct proc_mounts *p = m->private;
294	path_put(&p->root);
295	put_mnt_ns(p->ns);
296	return seq_release_private(inode, file);
297}
298
299static int mounts_open(struct inode *inode, struct file *file)
300{
301	return mounts_open_common(inode, file, show_vfsmnt);
302}
303
304static int mountinfo_open(struct inode *inode, struct file *file)
305{
306	return mounts_open_common(inode, file, show_mountinfo);
307}
308
309static int mountstats_open(struct inode *inode, struct file *file)
310{
311	return mounts_open_common(inode, file, show_vfsstat);
312}
313
314const struct file_operations proc_mounts_operations = {
315	.open		= mounts_open,
316	.read		= seq_read,
317	.llseek		= seq_lseek,
318	.release	= mounts_release,
319	.poll		= mounts_poll,
320};
321
322const struct file_operations proc_mountinfo_operations = {
323	.open		= mountinfo_open,
324	.read		= seq_read,
325	.llseek		= seq_lseek,
326	.release	= mounts_release,
327	.poll		= mounts_poll,
328};
329
330const struct file_operations proc_mountstats_operations = {
331	.open		= mountstats_open,
332	.read		= seq_read,
333	.llseek		= seq_lseek,
334	.release	= mounts_release,
335};
336