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tcp: gso: really support BIG TCP

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We missed that tcp_gso_segment() was assuming skb->len was smaller than 65535 :

oldlen = (u16)~skb->len;

This part came with commit 0718bcc09b ("[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: 09f3d1a3a5 ("ipv6/gso: remove temporary HBH/jumbo header")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230605161647.3624428-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2023-06-05 16:16:47 +00:00 committed by Jakub Kicinski
parent a2f4c143d7
commit 82a01ab35b
1 changed files with 9 additions and 10 deletions
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19
net/ipv4/tcp_offload.c
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@ -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