1 // SPDX-License-Identifier: GPL-2.0
3 * fs/proc_namespace.c - handling of /proc/<pid>/{mounts,mountinfo,mountstats}
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
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>
16 #include "proc/internal.h" /* only for get_proc_task() in ->open() */
21 static __poll_t mounts_poll(struct file *file, poll_table *wait)
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;
29 poll_wait(file, &p->ns->poll, wait);
31 event = READ_ONCE(ns->event);
32 if (m->poll_event != event) {
33 m->poll_event = event;
34 res |= EPOLLERR | EPOLLPRI;
45 static int show_sb_opts(struct seq_file *m, struct super_block *sb)
47 static const struct proc_fs_info fs_info[] = {
48 { SB_SYNCHRONOUS, ",sync" },
49 { SB_DIRSYNC, ",dirsync" },
50 { SB_MANDLOCK, ",mand" },
51 { SB_LAZYTIME, ",lazytime" },
54 const struct proc_fs_info *fs_infop;
56 for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
57 if (sb->s_flags & fs_infop->flag)
58 seq_puts(m, fs_infop->str);
61 return security_sb_show_options(m, sb);
64 static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
66 static const struct proc_fs_info mnt_info[] = {
67 { MNT_NOSUID, ",nosuid" },
68 { MNT_NODEV, ",nodev" },
69 { MNT_NOEXEC, ",noexec" },
70 { MNT_NOATIME, ",noatime" },
71 { MNT_NODIRATIME, ",nodiratime" },
72 { MNT_RELATIME, ",relatime" },
75 const struct proc_fs_info *fs_infop;
77 for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
78 if (mnt->mnt_flags & fs_infop->flag)
79 seq_puts(m, fs_infop->str);
83 static inline void mangle(struct seq_file *m, const char *s)
85 seq_escape(m, s, " \t\n\\");
88 static void show_type(struct seq_file *m, struct super_block *sb)
90 mangle(m, sb->s_type->name);
91 if (sb->s_subtype && sb->s_subtype[0]) {
93 mangle(m, sb->s_subtype);
97 static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)
99 struct proc_mounts *p = m->private;
100 struct mount *r = real_mount(mnt);
101 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
102 struct super_block *sb = mnt_path.dentry->d_sb;
105 if (sb->s_op->show_devname) {
106 err = sb->s_op->show_devname(m, mnt_path.dentry);
110 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
113 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
114 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
119 seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
120 err = show_sb_opts(m, sb);
123 show_mnt_opts(m, mnt);
124 if (sb->s_op->show_options2)
125 err = sb->s_op->show_options2(mnt, m, mnt_path.dentry);
126 else if (sb->s_op->show_options)
127 err = sb->s_op->show_options(m, mnt_path.dentry);
128 seq_puts(m, " 0 0\n");
133 static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
135 struct proc_mounts *p = m->private;
136 struct mount *r = real_mount(mnt);
137 struct super_block *sb = mnt->mnt_sb;
138 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
141 seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id,
142 MAJOR(sb->s_dev), MINOR(sb->s_dev));
143 if (sb->s_op->show_path) {
144 err = sb->s_op->show_path(m, mnt->mnt_root);
148 seq_dentry(m, mnt->mnt_root, " \t\n\\");
152 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
153 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
157 seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
158 show_mnt_opts(m, mnt);
160 /* Tagged fields ("foo:X" or "bar") */
161 if (IS_MNT_SHARED(r))
162 seq_printf(m, " shared:%i", r->mnt_group_id);
163 if (IS_MNT_SLAVE(r)) {
164 int master = r->mnt_master->mnt_group_id;
165 int dom = get_dominating_id(r, &p->root);
166 seq_printf(m, " master:%i", master);
167 if (dom && dom != master)
168 seq_printf(m, " propagate_from:%i", dom);
170 if (IS_MNT_UNBINDABLE(r))
171 seq_puts(m, " unbindable");
173 /* Filesystem specific data */
177 if (sb->s_op->show_devname) {
178 err = sb->s_op->show_devname(m, mnt->mnt_root);
182 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
184 seq_puts(m, sb_rdonly(sb) ? " ro" : " rw");
185 err = show_sb_opts(m, sb);
188 if (sb->s_op->show_options2) {
189 err = sb->s_op->show_options2(mnt, m, mnt->mnt_root);
190 } else if (sb->s_op->show_options)
191 err = sb->s_op->show_options(m, mnt->mnt_root);
197 static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt)
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;
206 if (sb->s_op->show_devname) {
207 seq_puts(m, "device ");
208 err = sb->s_op->show_devname(m, mnt_path.dentry);
212 if (r->mnt_devname) {
213 seq_puts(m, "device ");
214 mangle(m, r->mnt_devname);
216 seq_puts(m, "no device");
220 seq_puts(m, " mounted on ");
221 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
222 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
227 /* file system type */
228 seq_puts(m, "with fstype ");
231 /* optional statistics */
232 if (sb->s_op->show_stats) {
234 err = sb->s_op->show_stats(m, mnt_path.dentry);
242 static int mounts_open_common(struct inode *inode, struct file *file,
243 int (*show)(struct seq_file *, struct vfsmount *))
245 struct task_struct *task = get_proc_task(inode);
247 struct mnt_namespace *ns = NULL;
249 struct proc_mounts *p;
258 if (!nsp || !nsp->mnt_ns) {
260 put_task_struct(task);
267 put_task_struct(task);
271 get_fs_root(task->fs, &root);
273 put_task_struct(task);
275 ret = seq_open_private(file, &mounts_op, sizeof(struct proc_mounts));
279 m = file->private_data;
280 m->poll_event = ns->event;
286 p->cached_event = ~0ULL;
298 static int mounts_release(struct inode *inode, struct file *file)
300 struct seq_file *m = file->private_data;
301 struct proc_mounts *p = m->private;
304 return seq_release_private(inode, file);
307 static int mounts_open(struct inode *inode, struct file *file)
309 return mounts_open_common(inode, file, show_vfsmnt);
312 static int mountinfo_open(struct inode *inode, struct file *file)
314 return mounts_open_common(inode, file, show_mountinfo);
317 static int mountstats_open(struct inode *inode, struct file *file)
319 return mounts_open_common(inode, file, show_vfsstat);
322 const struct file_operations proc_mounts_operations = {
326 .release = mounts_release,
330 const struct file_operations proc_mountinfo_operations = {
331 .open = mountinfo_open,
334 .release = mounts_release,
338 const struct file_operations proc_mountstats_operations = {
339 .open = mountstats_open,
342 .release = mounts_release,