[mirror_ubuntu-bionic-kernel.git] / fs / proc_namespace.c

// SPDX-License-Identifier: GPL-2.0
/*
 * fs/proc_namespace.c - handling of /proc/<pid>/{mounts,mountinfo,mountstats}
 *
 * In fact, that's a piece of procfs; it's *almost* isolated from
 * the rest of fs/proc, but has rather close relationships with
 * fs/namespace.c, thus here instead of fs/proc
 *
 */
#include <linux/mnt_namespace.h>
#include <linux/nsproxy.h>
#include <linux/security.h>
#include <linux/fs_struct.h>
#include <linux/sched/task.h>

#include "proc/internal.h" /* only for get_proc_task() in ->open() */

#include "pnode.h"
#include "internal.h"

static unsigned mounts_poll(struct file *file, poll_table *wait)
{
	struct seq_file *m = file->private_data;
	struct proc_mounts *p = m->private;
	struct mnt_namespace *ns = p->ns;
	unsigned res = POLLIN | POLLRDNORM;
	int event;

	poll_wait(file, &p->ns->poll, wait);

	event = READ_ONCE(ns->event);
	if (m->poll_event != event) {
		m->poll_event = event;
		res |= POLLERR | POLLPRI;
	}

	return res;
}

struct proc_fs_info {
	int flag;
	const char *str;
};

static int show_sb_opts(struct seq_file *m, struct super_block *sb)
{
	static const struct proc_fs_info fs_info[] = {
		{ SB_SYNCHRONOUS, ",sync" },
		{ SB_DIRSYNC, ",dirsync" },
		{ SB_MANDLOCK, ",mand" },
		{ SB_LAZYTIME, ",lazytime" },
		{ 0, NULL }
	};
	const struct proc_fs_info *fs_infop;

	for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
		if (sb->s_flags & fs_infop->flag)
			seq_puts(m, fs_infop->str);
	}

	return security_sb_show_options(m, sb);
}

static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
{
	static const struct proc_fs_info mnt_info[] = {
		{ MNT_NOSUID, ",nosuid" },
		{ MNT_NODEV, ",nodev" },
		{ MNT_NOEXEC, ",noexec" },
		{ MNT_NOATIME, ",noatime" },
		{ MNT_NODIRATIME, ",nodiratime" },
		{ MNT_RELATIME, ",relatime" },
		{ 0, NULL }
	};
	const struct proc_fs_info *fs_infop;

	for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
		if (mnt->mnt_flags & fs_infop->flag)
			seq_puts(m, fs_infop->str);
	}
}

static inline void mangle(struct seq_file *m, const char *s)
{
	seq_escape(m, s, " \t\n\\");
}

static void show_type(struct seq_file *m, struct super_block *sb)
{
	mangle(m, sb->s_type->name);
	if (sb->s_subtype && sb->s_subtype[0]) {
		seq_putc(m, '.');
		mangle(m, sb->s_subtype);
	}
}

static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)
{
	struct proc_mounts *p = m->private;
	struct mount *r = real_mount(mnt);
	struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
	struct super_block *sb = mnt_path.dentry->d_sb;
	int err;

	if (sb->s_op->show_devname) {
		err = sb->s_op->show_devname(m, mnt_path.dentry);
		if (err)
			goto out;
	} else {
		mangle(m, r->mnt_devname ? r->mnt_devname : "none");
	}
	seq_putc(m, ' ');
	/* mountpoints outside of chroot jail will give SEQ_SKIP on this */
	err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
	if (err)
		goto out;
	seq_putc(m, ' ');
	show_type(m, sb);
	seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
	err = show_sb_opts(m, sb);
	if (err)
		goto out;
	show_mnt_opts(m, mnt);
	if (sb->s_op->show_options)
		err = sb->s_op->show_options(m, mnt_path.dentry);
	seq_puts(m, " 0 0\n");
out:
	return err;
}

static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
{
	struct proc_mounts *p = m->private;
	struct mount *r = real_mount(mnt);
	struct super_block *sb = mnt->mnt_sb;
	struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
	int err;

	seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id,
		   MAJOR(sb->s_dev), MINOR(sb->s_dev));
	if (sb->s_op->show_path) {
		err = sb->s_op->show_path(m, mnt->mnt_root);
		if (err)
			goto out;
	} else {
		seq_dentry(m, mnt->mnt_root, " \t\n\\");
	}
	seq_putc(m, ' ');

	/* mountpoints outside of chroot jail will give SEQ_SKIP on this */
	err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
	if (err)
		goto out;

	seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
	show_mnt_opts(m, mnt);

	/* Tagged fields ("foo:X" or "bar") */
	if (IS_MNT_SHARED(r))
		seq_printf(m, " shared:%i", r->mnt_group_id);
	if (IS_MNT_SLAVE(r)) {
		int master = r->mnt_master->mnt_group_id;
		int dom = get_dominating_id(r, &p->root);
		seq_printf(m, " master:%i", master);
		if (dom && dom != master)
			seq_printf(m, " propagate_from:%i", dom);
	}
	if (IS_MNT_UNBINDABLE(r))
		seq_puts(m, " unbindable");

	/* Filesystem specific data */
	seq_puts(m, " - ");
	show_type(m, sb);
	seq_putc(m, ' ');
	if (sb->s_op->show_devname) {
		err = sb->s_op->show_devname(m, mnt->mnt_root);
		if (err)
			goto out;
	} else {
		mangle(m, r->mnt_devname ? r->mnt_devname : "none");
	}
	seq_puts(m, sb_rdonly(sb) ? " ro" : " rw");
	err = show_sb_opts(m, sb);
	if (err)
		goto out;
	if (sb->s_op->show_options)
		err = sb->s_op->show_options(m, mnt->mnt_root);
	seq_putc(m, '\n');
out:
	return err;
}

static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt)
{
	struct proc_mounts *p = m->private;
	struct mount *r = real_mount(mnt);
	struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
	struct super_block *sb = mnt_path.dentry->d_sb;
	int err;

	/* device */
	if (sb->s_op->show_devname) {
		seq_puts(m, "device ");
		err = sb->s_op->show_devname(m, mnt_path.dentry);
		if (err)
			goto out;
	} else {
		if (r->mnt_devname) {
			seq_puts(m, "device ");
			mangle(m, r->mnt_devname);
		} else
			seq_puts(m, "no device");
	}

	/* mount point */
	seq_puts(m, " mounted on ");
	/* mountpoints outside of chroot jail will give SEQ_SKIP on this */
	err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
	if (err)
		goto out;
	seq_putc(m, ' ');

	/* file system type */
	seq_puts(m, "with fstype ");
	show_type(m, sb);

	/* optional statistics */
	if (sb->s_op->show_stats) {
		seq_putc(m, ' ');
		err = sb->s_op->show_stats(m, mnt_path.dentry);
	}

	seq_putc(m, '\n');
out:
	return err;
}

static int mounts_open_common(struct inode *inode, struct file *file,
			      int (*show)(struct seq_file *, struct vfsmount *))
{
	struct task_struct *task = get_proc_task(inode);
	struct nsproxy *nsp;
	struct mnt_namespace *ns = NULL;
	struct path root;
	struct proc_mounts *p;
	struct seq_file *m;
	int ret = -EINVAL;

	if (!task)
		goto err;

	task_lock(task);
	nsp = task->nsproxy;
	if (!nsp || !nsp->mnt_ns) {
		task_unlock(task);
		put_task_struct(task);
		goto err;
	}
	ns = nsp->mnt_ns;
	get_mnt_ns(ns);
	if (!task->fs) {
		task_unlock(task);
		put_task_struct(task);
		ret = -ENOENT;
		goto err_put_ns;
	}
	get_fs_root(task->fs, &root);
	task_unlock(task);
	put_task_struct(task);

	ret = seq_open_private(file, &mounts_op, sizeof(struct proc_mounts));
	if (ret)
		goto err_put_path;

	m = file->private_data;
	m->poll_event = ns->event;

	p = m->private;
	p->ns = ns;
	p->root = root;
	p->show = show;
	p->cached_event = ~0ULL;

	return 0;

 err_put_path:
	path_put(&root);
 err_put_ns:
	put_mnt_ns(ns);
 err:
	return ret;
}

static int mounts_release(struct inode *inode, struct file *file)
{
	struct seq_file *m = file->private_data;
	struct proc_mounts *p = m->private;
	path_put(&p->root);
	put_mnt_ns(p->ns);
	return seq_release_private(inode, file);
}

static int mounts_open(struct inode *inode, struct file *file)
{
	return mounts_open_common(inode, file, show_vfsmnt);
}

static int mountinfo_open(struct inode *inode, struct file *file)
{
	return mounts_open_common(inode, file, show_mountinfo);
}

static int mountstats_open(struct inode *inode, struct file *file)
{
	return mounts_open_common(inode, file, show_vfsstat);
}

const struct file_operations proc_mounts_operations = {
	.open		= mounts_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= mounts_release,
	.poll		= mounts_poll,
};

const struct file_operations proc_mountinfo_operations = {
	.open		= mountinfo_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= mounts_release,
	.poll		= mounts_poll,
};

const struct file_operations proc_mountstats_operations = {
	.open		= mountstats_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= mounts_release,
};
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
0226f492 AV	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>
f719ff9b IM	14	#include <linux/sched/task.h>
f719ff9b IM	15
0226f492 AV	16	#include "proc/internal.h" /* only for get_proc_task() in ->open() */
	17
	18	#include "pnode.h"
	19	#include "internal.h"
	20
	21	static unsigned mounts_poll(struct file file, poll_table wait)
	22	{
ede1bf0d YD	23	struct seq_file *m = file->private_data;
ede1bf0d YD	24	struct proc_mounts *p = m->private;
0226f492 AV	25	struct mnt_namespace *ns = p->ns;
0226f492 AV	26	unsigned res = POLLIN \| POLLRDNORM;
aab407fc	27	int event;
0226f492 AV	28
	29	poll_wait(file, &p->ns->poll, wait);
	30
6aa7de05	31	event = READ_ONCE(ns->event);
ede1bf0d YD	32	if (m->poll_event != event) {
ede1bf0d YD	33	m->poll_event = event;
0226f492 AV	34	res \|= POLLERR \| POLLPRI;
0226f492 AV	35	}
0226f492 AV	36
	37	return res;
	38	}
	39
	40	struct proc_fs_info {
	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_info fs_info[] = {
1751e8a6 LT	48	{ SB_SYNCHRONOUS, ",sync" },
	49	{ SB_DIRSYNC, ",dirsync" },
	50	{ SB_MANDLOCK, ",mand" },
	51	{ SB_LAZYTIME, ",lazytime" },
0226f492 AV	52	{ 0, NULL }
	53	};
	54	const struct proc_fs_info *fs_infop;
	55
	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);
	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_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" },
	73	{ 0, NULL }
	74	};
	75	const struct proc_fs_info *fs_infop;
	76
	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);
	80	}
	81	}
	82
	83	static inline void mangle(struct seq_file m, const char s)
	84	{
	85	seq_escape(m, s, " \t\n\\");
	86	}
	87
	88	static void show_type(struct seq_file m, struct super_block sb)
	89	{
	90	mangle(m, sb->s_type->name);
	91	if (sb->s_subtype && sb->s_subtype[0]) {
	92	seq_putc(m, '.');
	93	mangle(m, sb->s_subtype);
	94	}
	95	}
	96
	97	static int show_vfsmnt(struct seq_file m, struct vfsmount mnt)
	98	{
ede1bf0d	99	struct proc_mounts *p = m->private;
0226f492	100	struct mount *r = real_mount(mnt);
0226f492	101	struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
d861c630	102	struct super_block *sb = mnt_path.dentry->d_sb;
5d9f3c7b	103	int err;
0226f492	104
d861c630 AV	105	if (sb->s_op->show_devname) {
d861c630 AV	106	err = sb->s_op->show_devname(m, mnt_path.dentry);
0226f492 AV	107	if (err)
	108	goto out;
	109	} else {
	110	mangle(m, r->mnt_devname ? r->mnt_devname : "none");
	111	}
	112	seq_putc(m, ' ');
9d4d6574 DL	113	/* mountpoints outside of chroot jail will give SEQ_SKIP on this */
	114	err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
	115	if (err)
	116	goto out;
0226f492	117	seq_putc(m, ' ');
d861c630	118	show_type(m, sb);
0226f492	119	seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
d861c630	120	err = show_sb_opts(m, sb);
0226f492 AV	121	if (err)
	122	goto out;
	123	show_mnt_opts(m, mnt);
d861c630	124	if (sb->s_op->show_options)
34c80b1d	125	err = sb->s_op->show_options(m, mnt_path.dentry);
0226f492 AV	126	seq_puts(m, " 0 0\n");
	127	out:
	128	return err;
	129	}
	130
	131	static int show_mountinfo(struct seq_file m, struct vfsmount mnt)
	132	{
ede1bf0d	133	struct proc_mounts *p = m->private;
0226f492 AV	134	struct mount *r = real_mount(mnt);
	135	struct super_block *sb = mnt->mnt_sb;
	136	struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
6ce4bca0	137	int err;
0226f492 AV	138
	139	seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id,
	140	MAJOR(sb->s_dev), MINOR(sb->s_dev));
6ce4bca0	141	if (sb->s_op->show_path) {
a6322de6	142	err = sb->s_op->show_path(m, mnt->mnt_root);
6ce4bca0 DL	143	if (err)
	144	goto out;
	145	} else {
0226f492	146	seq_dentry(m, mnt->mnt_root, " \t\n\\");
6ce4bca0	147	}
0226f492 AV	148	seq_putc(m, ' ');
	149
	150	/* mountpoints outside of chroot jail will give SEQ_SKIP on this */
9ad4dc4f	151	err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
0226f492 AV	152	if (err)
	153	goto out;
	154
	155	seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
	156	show_mnt_opts(m, mnt);
	157
	158	/* Tagged fields ("foo:X" or "bar") */
	159	if (IS_MNT_SHARED(r))
	160	seq_printf(m, " shared:%i", r->mnt_group_id);
	161	if (IS_MNT_SLAVE(r)) {
	162	int master = r->mnt_master->mnt_group_id;
	163	int dom = get_dominating_id(r, &p->root);
	164	seq_printf(m, " master:%i", master);
	165	if (dom && dom != master)
	166	seq_printf(m, " propagate_from:%i", dom);
	167	}
	168	if (IS_MNT_UNBINDABLE(r))
	169	seq_puts(m, " unbindable");
	170
	171	/* Filesystem specific data */
	172	seq_puts(m, " - ");
	173	show_type(m, sb);
	174	seq_putc(m, ' ');
6ce4bca0	175	if (sb->s_op->show_devname) {
d861c630	176	err = sb->s_op->show_devname(m, mnt->mnt_root);
6ce4bca0 DL	177	if (err)
	178	goto out;
	179	} else {
0226f492	180	mangle(m, r->mnt_devname ? r->mnt_devname : "none");
6ce4bca0	181	}
bc98a42c	182	seq_puts(m, sb_rdonly(sb) ? " ro" : " rw");
0226f492 AV	183	err = show_sb_opts(m, sb);
	184	if (err)
	185	goto out;
	186	if (sb->s_op->show_options)
34c80b1d	187	err = sb->s_op->show_options(m, mnt->mnt_root);
0226f492 AV	188	seq_putc(m, '\n');
	189	out:
	190	return err;
	191	}
	192
	193	static int show_vfsstat(struct seq_file m, struct vfsmount mnt)
	194	{
ede1bf0d	195	struct proc_mounts *p = m->private;
0226f492 AV	196	struct mount *r = real_mount(mnt);
0226f492 AV	197	struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
64132379	198	struct super_block *sb = mnt_path.dentry->d_sb;
b896fb35	199	int err;
0226f492 AV	200
0226f492 AV	201	/* device */
64132379	202	if (sb->s_op->show_devname) {
0226f492	203	seq_puts(m, "device ");
d861c630	204	err = sb->s_op->show_devname(m, mnt_path.dentry);
5f8d498d DL	205	if (err)
5f8d498d DL	206	goto out;
0226f492 AV	207	} else {
	208	if (r->mnt_devname) {
	209	seq_puts(m, "device ");
	210	mangle(m, r->mnt_devname);
	211	} else
	212	seq_puts(m, "no device");
	213	}
	214
	215	/* mount point */
	216	seq_puts(m, " mounted on ");
9d4d6574 DL	217	/* mountpoints outside of chroot jail will give SEQ_SKIP on this */
	218	err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
	219	if (err)
	220	goto out;
0226f492 AV	221	seq_putc(m, ' ');
	222
	223	/* file system type */
	224	seq_puts(m, "with fstype ");
64132379	225	show_type(m, sb);
0226f492 AV	226
0226f492 AV	227	/* optional statistics */
64132379	228	if (sb->s_op->show_stats) {
0226f492	229	seq_putc(m, ' ');
b896fb35	230	err = sb->s_op->show_stats(m, mnt_path.dentry);
0226f492 AV	231	}
	232
	233	seq_putc(m, '\n');
9d4d6574	234	out:
0226f492 AV	235	return err;
	236	}
	237
	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;
ede1bf0d	246	struct seq_file *m;
0226f492 AV	247	int ret = -EINVAL;
	248
	249	if (!task)
	250	goto err;
	251
728dba3a EB	252	task_lock(task);
728dba3a EB	253	nsp = task->nsproxy;
3d93116c	254	if (!nsp \|\| !nsp->mnt_ns) {
728dba3a	255	task_unlock(task);
0226f492 AV	256	put_task_struct(task);
	257	goto err;
	258	}
	259	ns = nsp->mnt_ns;
0226f492	260	get_mnt_ns(ns);
0226f492 AV	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
ede1bf0d YD	271	ret = seq_open_private(file, &mounts_op, sizeof(struct proc_mounts));
ede1bf0d YD	272	if (ret)
0226f492 AV	273	goto err_put_path;
0226f492 AV	274
ede1bf0d YD	275	m = file->private_data;
ede1bf0d YD	276	m->poll_event = ns->event;
0226f492	277
ede1bf0d	278	p = m->private;
0226f492 AV	279	p->ns = ns;
0226f492 AV	280	p->root = root;
0226f492	281	p->show = show;
c7999c36	282	p->cached_event = ~0ULL;
0226f492 AV	283
	284	return 0;
	285
0226f492 AV	286	err_put_path:
	287	path_put(&root);
	288	err_put_ns:
	289	put_mnt_ns(ns);
	290	err:
	291	return ret;
	292	}
	293
	294	static int mounts_release(struct inode inode, struct file file)
	295	{
ede1bf0d YD	296	struct seq_file *m = file->private_data;
ede1bf0d YD	297	struct proc_mounts *p = m->private;
0226f492 AV	298	path_put(&p->root);
0226f492 AV	299	put_mnt_ns(p->ns);
ede1bf0d	300	return seq_release_private(inode, file);
0226f492 AV	301	}
	302
	303	static int mounts_open(struct inode inode, struct file file)
	304	{
	305	return mounts_open_common(inode, file, show_vfsmnt);
	306	}
	307
	308	static int mountinfo_open(struct inode inode, struct file file)
	309	{
	310	return mounts_open_common(inode, file, show_mountinfo);
	311	}
	312
	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	};