The extended IPv4 L4 header mode in act_pedit can select TCP or UDP
header fields without confirming that the IPv4 protocol field matches
the selected transport header.
That lets a rule written for TCP or UDP modify unrelated payload bytes
in a packet carrying a different protocol.
Verify that the IPv4 header is long enough, that the protocol matches
the selected TCP or UDP header, and that the packet is not a non-initial
fragment before applying TCP or UDP extended header edits.
Cc: stable+noautosel@kernel.org # in real rule sets the match confirms this before calling the action
Signed-off-by: Samuel Moelius <sam.moelius@trailofbits.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
d504a97857