The DNS resolution functionality in the CIFS implementation in the Linux
kernel before 2.6.35, when CONFIG_CIFS_DFS_UPCALL is enabled, relies on a
user's keyring for the dns_resolver upcall in the cifs.upcall userspace
helper, which allows local users to spoof the results of DNS queries and
perform arbitrary CIFS mounts via vectors involving an add_key call,
related to a "cache stuffing" issue and MS-DFS referrals.
David Howells discovered that DNS resolution in CIFS could be spoofed. A
local attacker could exploit this to control DNS replies, leading to a loss
of privacy and possible privilege escalation.
sbeattie> according to oss-security discussion, git commit 6103335de8afa5d780dcd512abe85c696af7b040
introduced the problem, so 2.6.25-rc1 onwards.
smb> Jaunty *may* be affected, but the problem is that there is no infra-
smb> structure for thread credentials, so even if it is possible to back-
smb> port the whole thing it would be completely different and prone to
smb> be incorrect. That together with the fact that Jaunty is EOL more or
smb> less I don't think we should put in much effort there.
Updated: 2016-01-26 17:36:38 UTC (commit 10507)