From: Cosmin Ratiu <cratiu@nvidia.com> mainline inclusion from mainline-v7.1-rc3 commit fa90a3145c0340c3f624206a81637c542254ea1d category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/15794 CVE: CVE-2026-53091 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- On VXLAN over IPsec egress, xfrm{4,6}_transport_output() blindly overwrite inner_transport_header (== the inner TCP header saved in VXLAN iptunnel_handle_offloads() -> skb_reset_inner_headers()) with the current transport_header (== the VXLAN outer UDP header set by udp_tunnel_xmit_skb()). This was a latent bug, harmless until commit [1] added a doff validation check in qdisc_pkt_len_segs_init() for encapsulated GSO packets. With the wrong inner_transport_header set by xfrm, qdisc_pkt_len_segs_init() interprets inner_transport_header as a TCP header, reads doff=0 from the upper byte of the VNI and drops the packet with DROP_REASON_SKB_BAD_GSO. Besides the use in GSO to determine the header size of segmented packets, inner_transport_header might be used by drivers to set up inner checksum offloading by pointing the HW to the inner transport header. A quick browse through available drivers shows that mlx5 uses skb->csum_start specifically for this scenario, while others either don't support VXLAN over IPsec crypto offload (ixgbe) or the HW is capable of parsing the packets itself (nfp, Chelsio). But in all cases, it is more correct to let the inner_transport_header point to the innermost header instead of overwriting it in xfrm. So fix this by guarding all four inner header save sites in xfrm_output.c (xfrm{4,6}_transport_output, xfrm{4,6}_tunnel_encap_add) with a check for skb->inner_protocol. When inner_protocol is set, a tunnel layer (VXLAN, Geneve, GRE, etc.) has already saved the correct inner header offsets and they must not be overwritten. When inner_protocol is zero, no prior tunnel encapsulation exists and xfrm must save the inner headers itself. The tunnel mode checks are only added for completion, since they aren't strictly required, as xfrm_output() forces software GSO in tunnel mode before encap. This makes the previously added test pass: # ./tools/testing/selftests/drivers/net/hw/ipsec_vxlan.py TAP version 13 1..4 ok 1 ipsec_vxlan.test_vxlan_ipsec_crypto_offload.outer_v4_inner_v4 ok 2 ipsec_vxlan.test_vxlan_ipsec_crypto_offload.outer_v4_inner_v6 ok 3 ipsec_vxlan.test_vxlan_ipsec_crypto_offload.outer_v6_inner_v4 ok 4 ipsec_vxlan.test_vxlan_ipsec_crypto_offload.outer_v6_inner_v6 # Totals: pass:4 fail:0 xfail:0 xpass:0 skip:0 error:0 [1] commit 7fb4c1967011 ("net: pull headers in qdisc_pkt_len_segs_init()") Fixes: f1bd7d659ef0 ("xfrm: Add encapsulation header offsets while SKB is not encrypted") Signed-off-by: Cosmin Ratiu <cratiu@nvidia.com> Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com> Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- net/xfrm/xfrm_output.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c index a5b5d82bd755..3f71bd425b2c 100644 --- a/net/xfrm/xfrm_output.c +++ b/net/xfrm/xfrm_output.c @@ -67,7 +67,9 @@ static int xfrm4_transport_output(struct xfrm_state *x, struct sk_buff *skb) struct iphdr *iph = ip_hdr(skb); int ihl = iph->ihl * 4; - skb_set_inner_transport_header(skb, skb_transport_offset(skb)); + if (!skb->inner_protocol) + skb_set_inner_transport_header(skb, + skb_transport_offset(skb)); skb_set_network_header(skb, -x->props.header_len); skb->mac_header = skb->network_header + @@ -168,7 +170,9 @@ static int xfrm6_transport_output(struct xfrm_state *x, struct sk_buff *skb) int hdr_len; iph = ipv6_hdr(skb); - skb_set_inner_transport_header(skb, skb_transport_offset(skb)); + if (!skb->inner_protocol) + skb_set_inner_transport_header(skb, + skb_transport_offset(skb)); hdr_len = xfrm6_hdr_offset(x, skb, &prevhdr); if (hdr_len < 0) @@ -277,8 +281,10 @@ static int xfrm4_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb) struct iphdr *top_iph; int flags; - skb_set_inner_network_header(skb, skb_network_offset(skb)); - skb_set_inner_transport_header(skb, skb_transport_offset(skb)); + if (!skb->inner_protocol) { + skb_set_inner_network_header(skb, skb_network_offset(skb)); + skb_set_inner_transport_header(skb, skb_transport_offset(skb)); + } skb_set_network_header(skb, -x->props.header_len); skb->mac_header = skb->network_header + @@ -322,8 +328,10 @@ static int xfrm6_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb) struct ipv6hdr *top_iph; int dsfield; - skb_set_inner_network_header(skb, skb_network_offset(skb)); - skb_set_inner_transport_header(skb, skb_transport_offset(skb)); + if (!skb->inner_protocol) { + skb_set_inner_network_header(skb, skb_network_offset(skb)); + skb_set_inner_transport_header(skb, skb_transport_offset(skb)); + } skb_set_network_header(skb, -x->props.header_len); skb->mac_header = skb->network_header + -- 2.25.1