From: Nick Bowler commit 8ee4f391831cb96916a8e8a05f04b1c1d7dd30d8 in mainline. In testing our ESP/AH offload hardware, I discovered an issue with how AH handles mutable fields in IPv4. RFC 4302 (AH) states the following on the subject: For IPv4, the entire option is viewed as a unit; so even though the type and length fields within most options are immutable in transit, if an option is classified as mutable, the entire option is zeroed for ICV computation purposes. The current implementation does not zero the type and length fields, resulting in authentication failures when communicating with hosts that do (i.e. FreeBSD). I have tested record route and timestamp options (ping -R and ping -T) on a small network involving Windows XP, FreeBSD 6.2, and Linux hosts, with one router. In the presence of these options, the FreeBSD and Linux hosts (with the patch or with the hardware) can communicate. The Windows XP host simply fails to accept these packets with or without the patch. I have also been trying to test source routing options (using traceroute -g), but haven't had much luck getting this option to work *without* AH, let alone with. Signed-off-by: Nick Bowler Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/ah4.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/ipv4/ah4.c +++ b/net/ipv4/ah4.c @@ -46,7 +46,7 @@ static int ip_clear_mutable_options(stru memcpy(daddr, optptr+optlen-4, 4); /* Fall through */ default: - memset(optptr+2, 0, optlen-2); + memset(optptr, 0, optlen); } l -= optlen; optptr += optlen; -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/