From 06a0afcfe2f551ff755849ea2549b0d8409fd9a0 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Fri, 10 Apr 2020 17:06:31 +0800 Subject: [PATCH] xfrm: do pskb_pull properly in __xfrm_transport_prep For transport mode, when ipv6 nexthdr is set, the packet format might be like: ---------------------------------------------------- | | dest | | | | ESP | ESP | | IP6 hdr| opts.| ESP | TCP | Data | Trailer | ICV | ---------------------------------------------------- and in __xfrm_transport_prep(): pskb_pull(skb, skb->mac_len + sizeof(ip6hdr) + x->props.header_len); it will pull the data pointer to the wrong position, as it missed the nexthdrs/dest opts. This patch is to fix it by using: pskb_pull(skb, skb_transport_offset(skb) + x->props.header_len); as we can be sure transport_header points to ESP header at that moment. It also fixes a panic when packets with ipv6 nexthdr are sent over esp6 transport mode: [ 100.473845] kernel BUG at net/core/skbuff.c:4325! [ 100.478517] RIP: 0010:__skb_to_sgvec+0x252/0x260 [ 100.494355] Call Trace: [ 100.494829] skb_to_sgvec+0x11/0x40 [ 100.495492] esp6_output_tail+0x12e/0x550 [esp6] [ 100.496358] esp6_xmit+0x1d5/0x260 [esp6_offload] [ 100.498029] validate_xmit_xfrm+0x22f/0x2e0 [ 100.499604] __dev_queue_xmit+0x589/0x910 [ 100.502928] ip6_finish_output2+0x2a5/0x5a0 [ 100.503718] ip6_output+0x6c/0x120 [ 100.505198] xfrm_output_resume+0x4bf/0x530 [ 100.508683] xfrm6_output+0x3a/0xc0 [ 100.513446] inet6_csk_xmit+0xa1/0xf0 [ 100.517335] tcp_sendmsg+0x27/0x40 [ 100.517977] sock_sendmsg+0x3e/0x60 [ 100.518648] __sys_sendto+0xee/0x160 Fixes: c35fe4106b92 ("xfrm: Add mode handlers for IPsec on layer 2") Signed-off-by: Xin Long Signed-off-by: Steffen Klassert --- net/xfrm/xfrm_device.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/net/xfrm/xfrm_device.c b/net/xfrm/xfrm_device.c index 6cc7f7f1dd68..f50d1f97cf8e 100644 --- a/net/xfrm/xfrm_device.c +++ b/net/xfrm/xfrm_device.c @@ -25,12 +25,10 @@ static void __xfrm_transport_prep(struct xfrm_state *x, struct sk_buff *skb, struct xfrm_offload *xo = xfrm_offload(skb); skb_reset_mac_len(skb); - pskb_pull(skb, skb->mac_len + hsize + x->props.header_len); - - if (xo->flags & XFRM_GSO_SEGMENT) { - skb_reset_transport_header(skb); + if (xo->flags & XFRM_GSO_SEGMENT) skb->transport_header -= x->props.header_len; - } + + pskb_pull(skb, skb_transport_offset(skb) + x->props.header_len); } static void __xfrm_mode_tunnel_prep(struct xfrm_state *x, struct sk_buff *skb,