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-rw-r--r--fs/namei.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/fs/namei.c b/fs/namei.c
index 629823f19a6a..ef573df3297f 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -36,6 +36,7 @@
#include <linux/posix_acl.h>
#include <linux/hash.h>
#include <linux/bitops.h>
+#include <linux/init_task.h>
#include <asm/uaccess.h>
#include "internal.h"
@@ -1099,6 +1100,7 @@ static int follow_automount(struct path *path, struct nameidata *nd,
bool *need_mntput)
{
struct vfsmount *mnt;
+ const struct cred *old_cred;
int err;
if (!path->dentry->d_op || !path->dentry->d_op->d_automount)
@@ -1120,11 +1122,16 @@ static int follow_automount(struct path *path, struct nameidata *nd,
path->dentry->d_inode)
return -EISDIR;
+ if (path->dentry->d_sb->s_user_ns != &init_user_ns)
+ return -EACCES;
+
nd->total_link_count++;
if (nd->total_link_count >= 40)
return -ELOOP;
+ old_cred = override_creds(&init_cred);
mnt = path->dentry->d_op->d_automount(path);
+ revert_creds(old_cred);
if (IS_ERR(mnt)) {
/*
* The filesystem is allowed to return -EISDIR here to indicate