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author | Andy Lutomirski <luto@amacapital.net> | 2014-06-10 12:45:42 -0700 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-06-16 13:42:52 -0700 |
commit | 4f80c6c1825a91cecf3b3bd19c824e768d98fe48 (patch) | |
tree | cdb4e44336c2a34d559d3a609784d74a37c7301a /fs/inode.c | |
parent | 853771148c5aa5998c423ed4dddd7605d4b4c949 (diff) | |
download | lwn-4f80c6c1825a91cecf3b3bd19c824e768d98fe48.tar.gz lwn-4f80c6c1825a91cecf3b3bd19c824e768d98fe48.zip |
fs,userns: Change inode_capable to capable_wrt_inode_uidgid
commit 23adbe12ef7d3d4195e80800ab36b37bee28cd03 upstream.
The kernel has no concept of capabilities with respect to inodes; inodes
exist independently of namespaces. For example, inode_capable(inode,
CAP_LINUX_IMMUTABLE) would be nonsense.
This patch changes inode_capable to check for uid and gid mappings and
renames it to capable_wrt_inode_uidgid, which should make it more
obvious what it does.
Fixes CVE-2014-4014.
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Serge Hallyn <serge.hallyn@ubuntu.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/inode.c')
-rw-r--r-- | fs/inode.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/fs/inode.c b/fs/inode.c index 00d5fc3b86e1..1b300a06b8be 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -1837,14 +1837,18 @@ EXPORT_SYMBOL(inode_init_owner); * inode_owner_or_capable - check current task permissions to inode * @inode: inode being checked * - * Return true if current either has CAP_FOWNER to the inode, or - * owns the file. + * Return true if current either has CAP_FOWNER in a namespace with the + * inode owner uid mapped, or owns the file. */ bool inode_owner_or_capable(const struct inode *inode) { + struct user_namespace *ns; + if (uid_eq(current_fsuid(), inode->i_uid)) return true; - if (inode_capable(inode, CAP_FOWNER)) + + ns = current_user_ns(); + if (ns_capable(ns, CAP_FOWNER) && kuid_has_mapping(ns, inode->i_uid)) return true; return false; } |