diff mbox series

[v2,net] tcp: gso: really support BIG TCP

Message ID 20230605161647.3624428-1-edumazet@google.com (mailing list archive)
State Accepted
Commit 82a01ab35bd02ba4b0b4e12bc95c5b69240eb7b0
Delegated to: Netdev Maintainers
Headers show
Series [v2,net] tcp: gso: really support BIG TCP | expand

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Context Check Description
netdev/series_format success Single patches do not need cover letters
netdev/tree_selection success Clearly marked for net
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 14 this patch: 14
netdev/cc_maintainers warning 1 maintainers not CCed: dsahern@kernel.org
netdev/build_clang success Errors and warnings before: 8 this patch: 8
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 14 this patch: 14
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 54 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Eric Dumazet June 5, 2023, 4:16 p.m. UTC 
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 <edumazet@google.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
---
 net/ipv4/tcp_offload.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

Comments

Simon Horman June 6, 2023, 8:12 a.m. UTC | #1 
On Mon, Jun 05, 2023 at 04:16:47PM +0000, Eric Dumazet wrote:
> 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 <edumazet@google.com>
> Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>

Reviewed-by: Simon Horman <simon.horman@corigine.com>
patchwork-bot+netdevbpf@kernel.org June 7, 2023, 4:10 a.m. UTC | #2 
Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Mon,  5 Jun 2023 16:16:47 +0000 you wrote:
> 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.
> 
> [...]

Here is the summary with links:
  - [v2,net] tcp: gso: really support BIG TCP
    https://git.kernel.org/netdev/net/c/82a01ab35bd0

You are awesome, thank you!
diff mbox series

Patch

diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index 45dda788938704c3f762256266d9ea29b6ded4a5..4851211aa60d6eaf7d1c5e4f90bbcf621ee4c69b 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