tree 736ba574091e9959f0e47fa2be122b46f26e372d
parent 9531ab65f4ec066a6e6617a08a293c60397a161b
author Willem de Bruijn <willemb@google.com> 1457578712 -0500
committer David S. Miller <davem@davemloft.net> 1457579581 -0500

net: validate variable length ll headers

Netdevice parameter hard_header_len is variously interpreted both as
an upper and lower bound on link layer header length. The field is
used as upper bound when reserving room at allocation, as lower bound
when validating user input in PF_PACKET.

Clarify the definition to be maximum header length. For validation
of untrusted headers, add an optional validate member to header_ops.

Allow bypassing of validation by passing CAP_SYS_RAWIO, for instance
for deliberate testing of corrupt input. In this case, pad trailing
bytes, as some device drivers expect completely initialized headers.

See also http://comments.gmane.org/gmane.linux.network/401064

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>