From: Steffen Klassert Subject: [PATCH] esp4: Fix udpencap for local TCP packets. Locally generated TCP packets are usually cloned, so we do skb_cow_data() on this packets. After that we need to reload the pointer to the esp header. On udpencap this header has an offset to skb_transport_header, so take this offset into account. Fixes: commit cac2661c53f ("esp4: Avoid skb_cow_data whenever possible") Signed-off-by: Steffen Klassert --- net/ipv4/esp4.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c index b1e2444..ab71fbb 100644 --- a/net/ipv4/esp4.c +++ b/net/ipv4/esp4.c @@ -223,6 +223,7 @@ static int esp_output(struct xfrm_state *x, struct sk_buff *skb) int extralen; int tailen; __be64 seqno; + int esp_offset = 0; __u8 proto = *skb_mac_header(skb); /* skb is pure payload to encrypt */ @@ -288,6 +289,8 @@ static int esp_output(struct xfrm_state *x, struct sk_buff *skb) break; } + esp_offset = (unsigned char *)esph - (unsigned char *)uh; + *skb_mac_header(skb) = IPPROTO_UDP; } @@ -397,7 +400,7 @@ static int esp_output(struct xfrm_state *x, struct sk_buff *skb) goto error; nfrags = err; tail = skb_tail_pointer(trailer); - esph = ip_esp_hdr(skb); + esph = (struct ip_esp_hdr *)(skb_transport_header(skb) + esp_offset); skip_cow: esp_output_fill_trailer(tail, tfclen, plen, proto);