Jianlin reported a panic when running sctp gso over gre over vlan device:
[ 84.772930] RIP: 0010:do_csum+0x6d/0x170
[ 84.790605] Call Trace:
[ 84.791054] csum_partial+0xd/0x20
[ 84.791657] gre_gso_segment+0x2c3/0x390
[ 84.792364] inet_gso_segment+0x161/0x3e0
[ 84.793071] skb_mac_gso_segment+0xb8/0x120
[ 84.793846] __skb_gso_segment+0x7e/0x180
[ 84.794581] validate_xmit_skb+0x141/0x2e0
[ 84.795297] __dev_queue_xmit+0x258/0x8f0
[ 84.795949] ? eth_header+0x26/0xc0
[ 84.796581] ip_finish_output2+0x196/0x430
[ 84.797295] ? skb_gso_validate_network_len+0x11/0x80
[ 84.798183] ? ip_finish_output+0x169/0x270
[ 84.798875] ip_output+0x6c/0xe0
[ 84.799413] ? ip_append_data.part.50+0xc0/0xc0
[ 84.800145] iptunnel_xmit+0x144/0x1c0
[ 84.800814] ip_tunnel_xmit+0x62d/0x930 [ip_tunnel]
[ 84.801699] gre_tap_xmit+0xac/0xf0 [ip_gre]
[ 84.802395] dev_hard_start_xmit+0xa5/0x210
[ 84.803086] sch_direct_xmit+0x14f/0x340
[ 84.803733] __dev_queue_xmit+0x799/0x8f0
[ 84.804472] ip_finish_output2+0x2e0/0x430
[ 84.805255] ? skb_gso_validate_network_len+0x11/0x80
[ 84.806154] ip_output+0x6c/0xe0
[ 84.806721] ? ip_append_data.part.50+0xc0/0xc0
[ 84.807516] sctp_packet_transmit+0x716/0xa10 [sctp]
[ 84.808337] sctp_outq_flush+0xd7/0x880 [sctp]
It was caused by SKB_GSO_CB(skb)->csum_start not set in sctp_gso_segment.
sctp_gso_segment() calls skb_segment() with 'feature | NETIF_F_HW_CSUM',
which causes SKB_GSO_CB(skb)->csum_start not to be set in skb_segment().
For TCP/UDP, when feature supports HW_CSUM, CHECKSUM_PARTIAL will be set
and gso_reset_checksum will be called to set SKB_GSO_CB(skb)->csum_start.
So SCTP should do the same as TCP/UDP, to call gso_reset_checksum() when
computing checksum in sctp_gso_segment.
Reported-by: Jianlin Shi <jishi@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
As well as the basic conversion, I noticed that a lot of the
SCTP code checks gso_type without first checking skb_is_gso()
so I have added that where appropriate.
Also, document the helper.
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Validate gso_type during segmentation as SKB_GSO_DODGY sources
may pass packets where the gso_type does not match the contents.
Syzkaller was able to enter the SCTP gso handler with a packet of
gso_type SKB_GSO_TCPV4.
On entry of transport layer gso handlers, verify that the gso_type
matches the transport protocol.
Fixes: 90017accff ("sctp: Add GSO support")
Link: http://lkml.kernel.org/r/<001a1137452496ffc305617e5fe0@google.com>
Reported-by: syzbot+fee64147a25aecd48055@syzkaller.appspotmail.com
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
skb->csum_not_inet carries the indication on which algorithm is needed to
compute checksum on skb in the transmit path, when skb->ip_summed is equal
to CHECKSUM_PARTIAL. If skb carries a SCTP packet and crc32c hasn't been
yet written in L4 header, skb->csum_not_inet is assigned to 1; otherwise,
assume Internet Checksum is needed and thus set skb->csum_not_inet to 0.
Suggested-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Acked-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
sctp_compute_checksum requires crc32c symbol (provided by libcrc32c), so
it can't be used in net core. Like it has been done previously with other
symbols (e.g. ipv6_dst_lookup), introduce a stub struct skb_checksum_ops
to allow computation of crc32c checksum in net core after sctp.ko (and thus
libcrc32c) has been loaded.
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Now sctp gso puts segments into skb's frag_list, then processes these
segments in skb_segment. But skb_segment handles them only when gs is
enabled, as it's in the same branch with skb's frags.
Although almost all the NICs support sg other than some old ones, but
since commit 1e16aa3ddf ("net: gso: use feature flag argument in all
protocol gso handlers"), features &= skb->dev->hw_enc_features, and
xfrm_output_gso call skb_segment with features = 0, which means sctp
gso would call skb_segment with sg = 0, and skb_segment would not work
as expected.
This patch is to fix it by setting features param with NETIF_F_SG when
calling skb_segment so that it can go the right branch to process the
skb's frag_list.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
commit 90017accff ("sctp: Add GSO support") didn't register SCTP GSO
offloading for IPv6 and yet didn't put any restrictions on generating
GSO packets while in IPv6, which causes all IPv6 GSO'ed packets to be
silently dropped.
The fix is to properly register the offload this time.
Fixes: 90017accff ("sctp: Add GSO support")
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
SCTP has this pecualiarity that its packets cannot be just segmented to
(P)MTU. Its chunks must be contained in IP segments, padding respected.
So we can't just generate a big skb, set gso_size to the fragmentation
point and deliver it to IP layer.
This patch takes a different approach. SCTP will now build a skb as it
would be if it was received using GRO. That is, there will be a cover
skb with protocol headers and children ones containing the actual
segments, already segmented to a way that respects SCTP RFCs.
With that, we can tell skb_segment() to just split based on frag_list,
trusting its sizes are already in accordance.
This way SCTP can benefit from GSO and instead of passing several
packets through the stack, it can pass a single large packet.
v2:
- Added support for receiving GSO frames, as requested by Dave Miller.
- Clear skb->cb if packet is GSO (otherwise it's not used by SCTP)
- Added heuristics similar to what we have in TCP for not generating
single GSO packets that fills cwnd.
v3:
- consider sctphdr size in skb_gso_transport_seglen()
- rebased due to 5c7cdf339a ("gso: Remove arbitrary checks for
unsupported GSO")
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Tested-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Xin Long