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| author | Seth Forshee <seth.forshee@canonical.com> | 2016-04-26 14:36:23 -0500 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2016-06-30 18:05:09 -0500 |
| commit | 2d7f9e2ad35e4e7a3086231f19bfab33c6a8a64a (patch) | |
| tree | 120e1da5af655549c3a918c4c4e6afcb744e1527 /fs/namei.c | |
| parent | 0d4d717f25834134bb6f43284f84c8ccee5bbf2a (diff) | |
| download | lwn-2d7f9e2ad35e4e7a3086231f19bfab33c6a8a64a.tar.gz lwn-2d7f9e2ad35e4e7a3086231f19bfab33c6a8a64a.zip | |
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.c | 4 |
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) |