On Mon, Feb 18, 2019 at 1:50 PM Sasha Levin <sas...@kernel.org> wrote: > > On Thu, Jan 17, 2019 at 03:55:27PM -0800, David Miller wrote: > >From: Nicolas Dichtel <nicolas.dich...@6wind.com> > >Date: Thu, 17 Jan 2019 11:27:22 +0100 > > > >> Since commit cb9f1b783850, scapy (which uses an AF_PACKET socket in > >> SOCK_RAW mode) is unable to send a basic icmp packet over a sit tunnel: > >> > >> Here is a example of the setup: > >> $ ip link set ntfp2 up > >> $ ip addr add 10.125.0.1/24 dev ntfp2 > >> $ ip tunnel add tun1 mode sit ttl 64 local 10.125.0.1 remote 10.125.0.2 > >> dev ntfp2 > >> $ ip addr add fd00:cafe:cafe::1/128 dev tun1 > >> $ ip link set dev tun1 up > >> $ ip route add fd00:200::/64 dev tun1 > >> $ scapy > >>>>> p = [] > >>>>> p += IPv6(src='fd00:100::1', dst='fd00:200::1')/ICMPv6EchoRequest() > >>>>> send(p, count=1, inter=0.1) > >>>>> quit() > >> $ ip -s link ls dev tun1 | grep -A1 "TX.*errors" > >> TX: bytes packets errors dropped carrier collsns > >> 0 0 1 0 0 0 > >> > >> The problem is that the network offset is set to the hard_header_len of the > >> output device (tun1, ie 14 + 20) and in our case, because the packet is > >> small (48 bytes) the pskb_inet_may_pull() fails (it tries to pull 40 bytes > >> (ipv6 header) starting from the network offset). > >> > >> This problem is more generally related to device with variable hard header > >> length. To avoid a too intrusive patch in the current release, a (ugly) > >> workaround is proposed in this patch. It has to be cleaned up in net-next. > >> > >> Link: > >> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=993675a3100b1 > >> Link: http://patchwork.ozlabs.org/patch/1024489/ > >> Fixes: cb9f1b783850 ("ip: validate header length on virtual device xmit") > >> CC: Willem de Bruijn <will...@google.com> > >> CC: Maxim Mikityanskiy <maxi...@mellanox.com> > >> Signed-off-by: Nicolas Dichtel <nicolas.dich...@6wind.com> > >> --- > >> > >> v1 -> v2: > >> reset nh offset only for small packets sent on a variable hard hdr len > >> device > > > >Applied. > > Should this go to -stable as well? The patch it fixes is in 4.20.
I believe so. It was also backported to 4.19 stable.
