On Sun, Aug 05, 2018 at 04:28:11PM +0100, Al Viro wrote: > On little-endian host those do yield the right values - e.g. 0x1100 is > {0, 17, 0, 0}, etc. On big-endian, though, these will end up checking > in IPv4 case the octet at offset 10 (i.e. upper 16 bits of checksum) and for > IPv6 > - the octet at offset 5 (i.e. the lower 8 bits of payload length). > > Unless I'm misreading that code, it needs the following to do the right > thing both on l-e and b-e. Comments?
... and it looks like the same story with ->mask - it's compared to ->offmask, which is __be16. For little-endian hosts the values make sense (htons(0x0f00), with offoff 0 and shift 6, i.e. "take the first two octets, treat them as net-endian, clear everything except IHL bits and shift down by 6, which'd yield IHL*4"), for big-endian they don't - you'd get TOS * 4 instead...