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authorLinus Torvalds <torvalds@linux-foundation.org>2015-11-05 15:20:56 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-11-05 15:20:56 -0800
commit6de29ccb50f2caef07cdd888efc8cb933497b6a4 (patch)
treec08336d487fb8f275e9ded66b4a648abbac7d39e /fs
parent69234acee54407962a20bedf90ef9c96326994b5 (diff)
parentf2ca379642d7a843be972ea4167abdd3c8c9e5d1 (diff)
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull userns hardlink capability check fix from Eric Biederman: "This round just contains a single patch. There has been a lot of other work this period but it is not quite ready yet, so I am pushing it until 4.5. The remaining change by Dirk Steinmetz wich fixes both Gentoo and Ubuntu containers allows hardlinks if we have the appropriate capabilities in the user namespace. Security wise it is really a gimme as the user namespace root can already call setuid become that user and create the hardlink" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: namei: permit linking with CAP_FOWNER in userns
Diffstat (limited to 'fs')
-rw-r--r--fs/namei.c7
1 files changed, 2 insertions, 5 deletions
diff --git a/fs/namei.c b/fs/namei.c
index 33e9495a3129..0d3340b32e14 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -955,26 +955,23 @@ static bool safe_hardlink_source(struct inode *inode)
* - sysctl_protected_hardlinks enabled
* - fsuid does not match inode
* - hardlink source is unsafe (see safe_hardlink_source() above)
- * - not CAP_FOWNER
+ * - not CAP_FOWNER in a namespace with the inode owner uid mapped
*
* Returns 0 if successful, -ve on error.
*/
static int may_linkat(struct path *link)
{
- const struct cred *cred;
struct inode *inode;
if (!sysctl_protected_hardlinks)
return 0;
- cred = current_cred();
inode = link->dentry->d_inode;
/* Source inode owner (or CAP_FOWNER) can hardlink all they like,
* otherwise, it must be a safe source.
*/
- if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) ||
- capable(CAP_FOWNER))
+ if (inode_owner_or_capable(inode) || safe_hardlink_source(inode))
return 0;
audit_log_link_denied("linkat", link);