diff options
| author | Seth Forshee <seth.forshee@canonical.com> | 2016-08-30 00:35:00 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-09-15 08:27:49 +0200 |
| commit | 6a90aa44065afb34ad4f37676b734c0e3eeafe6a (patch) | |
| tree | a005b33130c7b9652455fb2efcafd90fe022ce11 | |
| parent | 917f84b8df10b6959f0fb8e5019cdffb670c0362 (diff) | |
fs: Check for invalid i_uid in may_follow_link()
[ Upstream commit 2d7f9e2ad35e4e7a3086231f19bfab33c6a8a64a ]
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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/namei.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/namei.c b/fs/namei.c index 209ca7737cb2..0b0acba72a71 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -887,6 +887,7 @@ 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; @@ -902,7 +903,8 @@ 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) |