From 82a01ab35bd02ba4b0b4e12bc95c5b69240eb7b0 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 5 Jun 2023 16:16:47 +0000 Subject: [PATCH] tcp: gso: really support BIG TCP We missed that tcp_gso_segment() was assuming skb->len was smaller than 65535 : oldlen = (u16)~skb->len; This part came with commit 0718bcc09b35 ("[NET]: Fix CHECKSUM_HW GSO problems.") This leads to wrong TCP checksum. Adapt the code to accept arbitrary packet length. v2: - use two csum_add() instead of csum_fold() (Alexander Duyck) - Change delta type to __wsum to reduce casts (Alexander Duyck) Fixes: 09f3d1a3a52c ("ipv6/gso: remove temporary HBH/jumbo header") Signed-off-by: Eric Dumazet Reviewed-by: Alexander Duyck Reviewed-by: Simon Horman Link: https://lore.kernel.org/r/20230605161647.3624428-1-edumazet@google.com Signed-off-by: Jakub Kicinski --- net/ipv4/tcp_offload.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c index 45dda7889387..4851211aa60d 100644 --- a/net/ipv4/tcp_offload.c +++ b/net/ipv4/tcp_offload.c @@ -60,12 +60,12 @@ struct sk_buff *tcp_gso_segment(struct sk_buff *skb, struct tcphdr *th; unsigned int thlen; unsigned int seq; - __be32 delta; unsigned int oldlen; unsigned int mss; struct sk_buff *gso_skb = skb; __sum16 newcheck; bool ooo_okay, copy_destructor; + __wsum delta; th = tcp_hdr(skb); thlen = th->doff * 4; @@ -75,7 +75,7 @@ struct sk_buff *tcp_gso_segment(struct sk_buff *skb, if (!pskb_may_pull(skb, thlen)) goto out; - oldlen = (u16)~skb->len; + oldlen = ~skb->len; __skb_pull(skb, thlen); mss = skb_shinfo(skb)->gso_size; @@ -110,7 +110,7 @@ struct sk_buff *tcp_gso_segment(struct sk_buff *skb, if (skb_is_gso(segs)) mss *= skb_shinfo(segs)->gso_segs; - delta = htonl(oldlen + (thlen + mss)); + delta = (__force __wsum)htonl(oldlen + thlen + mss); skb = segs; th = tcp_hdr(skb); @@ -119,8 +119,7 @@ struct sk_buff *tcp_gso_segment(struct sk_buff *skb, if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP)) tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss); - newcheck = ~csum_fold((__force __wsum)((__force u32)th->check + - (__force u32)delta)); + newcheck = ~csum_fold(csum_add(csum_unfold(th->check), delta)); while (skb->next) { th->fin = th->psh = 0; @@ -165,11 +164,11 @@ struct sk_buff *tcp_gso_segment(struct sk_buff *skb, WARN_ON_ONCE(refcount_sub_and_test(-delta, &skb->sk->sk_wmem_alloc)); } - delta = htonl(oldlen + (skb_tail_pointer(skb) - - skb_transport_header(skb)) + - skb->data_len); - th->check = ~csum_fold((__force __wsum)((__force u32)th->check + - (__force u32)delta)); + delta = (__force __wsum)htonl(oldlen + + (skb_tail_pointer(skb) - + skb_transport_header(skb)) + + skb->data_len); + th->check = ~csum_fold(csum_add(csum_unfold(th->check), delta)); if (skb->ip_summed == CHECKSUM_PARTIAL) gso_reset_checksum(skb, ~th->check); else