1 files changed, 348 insertions, 0 deletions
diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c
new file mode 100644
index 000000000..846f9455a
--- /dev/null
+++ b/fs/proc_namespace.c
@@ -0,0 +1,348 @@
+// 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 __poll_t 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;
+	__poll_t res = EPOLLIN | EPOLLRDNORM;
+	int event;
+
+	poll_wait(file, &p->ns->poll, wait);
+
+	event = READ_ONCE(ns->event);
+	if (m->poll_event != event) {
+		m->poll_event = event;
+		res |= EPOLLERR | EPOLLPRI;
+	}
+
+	return res;
+}
+
+struct proc_fs_opts {
+	int flag;
+	const char *str;
+};
+
+static int show_sb_opts(struct seq_file *m, struct super_block *sb)
+{
+	static const struct proc_fs_opts fs_opts[] = {
+		{ SB_SYNCHRONOUS, ",sync" },
+		{ SB_DIRSYNC, ",dirsync" },
+		{ SB_MANDLOCK, ",mand" },
+		{ SB_LAZYTIME, ",lazytime" },
+		{ 0, NULL }
+	};
+	const struct proc_fs_opts *fs_infop;
+
+	for (fs_infop = fs_opts; 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_opts mnt_opts[] = {
+		{ MNT_NOSUID, ",nosuid" },
+		{ MNT_NODEV, ",nodev" },
+		{ MNT_NOEXEC, ",noexec" },
+		{ MNT_NOATIME, ",noatime" },
+		{ MNT_NODIRATIME, ",nodiratime" },
+		{ MNT_RELATIME, ",relatime" },
+		{ MNT_NOSYMFOLLOW, ",nosymfollow" },
+		{ 0, NULL }
+	};
+	const struct proc_fs_opts *fs_infop;
+
+	for (fs_infop = mnt_opts; fs_infop->flag; fs_infop++) {
+		if (mnt->mnt_flags & fs_infop->flag)
+			seq_puts(m, fs_infop->str);
+	}
+
+	if (is_idmapped_mnt(mnt))
+		seq_puts(m, ",idmapped");
+}
+
+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) {
+		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;
+	INIT_LIST_HEAD(&p->cursor.mnt_list);
+	p->cursor.mnt.mnt_flags = MNT_CURSOR;
+
+	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);
+	mnt_cursor_del(p->ns, &p->cursor);
+	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_iter	= seq_read_iter,
+	.splice_read	= generic_file_splice_read,
+	.llseek		= seq_lseek,
+	.release	= mounts_release,
+	.poll		= mounts_poll,
+};
+
+const struct file_operations proc_mountinfo_operations = {
+	.open		= mountinfo_open,
+	.read_iter	= seq_read_iter,
+	.splice_read	= generic_file_splice_read,
+	.llseek		= seq_lseek,
+	.release	= mounts_release,
+	.poll		= mounts_poll,
+};
+
+const struct file_operations proc_mountstats_operations = {
+	.open		= mountstats_open,
+	.read_iter	= seq_read_iter,
+	.splice_read	= generic_file_splice_read,
+	.llseek		= seq_lseek,
+	.release	= mounts_release,
+};