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authorSeth Forshee <seth.forshee@canonical.com>2016-04-26 22:36:23 +0300
committerEric W. Biederman <ebiederm@xmission.com>2016-07-01 02:05:09 +0300
commit2d7f9e2ad35e4e7a3086231f19bfab33c6a8a64a (patch)
tree120e1da5af655549c3a918c4c4e6afcb744e1527 /fs/namei.c
parent0d4d717f25834134bb6f43284f84c8ccee5bbf2a (diff)
downloadlinux-2d7f9e2ad35e4e7a3086231f19bfab33c6a8a64a.tar.xz
fs: Check for invalid i_uid in may_follow_link()
Filesystem uids which don't map into a user namespace may result in inode->i_uid being INVALID_UID. A symlink and its parent could have different owners in the filesystem can both get mapped to INVALID_UID, which may result in following a symlink when this would not have otherwise been permitted when protected symlinks are enabled. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'fs/namei.c')
-rw-r--r--fs/namei.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/namei.c b/fs/namei.c
index 757a32725d92..8701bd9a5270 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -901,6 +901,7 @@ static inline int may_follow_link(struct nameidata *nd)
{
const struct inode *inode;
const struct inode *parent;
+ kuid_t puid;
if (!sysctl_protected_symlinks)
return 0;
@@ -916,7 +917,8 @@ static inline int may_follow_link(struct nameidata *nd)
return 0;
/* Allowed if parent directory and link owner match. */
- if (uid_eq(parent->i_uid, inode->i_uid))
+ puid = parent->i_uid;
+ if (uid_valid(puid) && uid_eq(puid, inode->i_uid))
return 0;
if (nd->flags & LOOKUP_RCU)