From: Herbert Xu on
tcp: Handle CHECKSUM_PARTIAL for SYNACK packets for IPv6

This patch moves the common code between tcp_v6_send_check and
tcp_v6_gso_send_check into a new function __tcp_v6_send_check.

It then uses the new function in tcp_v6_send_synack as well as
tcp_v6_send_response so that they handle CHECKSUM_PARTIAL properly.

Signed-off-by: Herbert Xu <herbert(a)gondor.apana.org.au>
---

net/ipv6/tcp_ipv6.c | 37 +++++++++++++++++++------------------
1 file changed, 19 insertions(+), 18 deletions(-)

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index c92ebe8..f84c506 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -75,6 +75,9 @@ static void tcp_v6_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
struct request_sock *req);

static int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb);
+static void __tcp_v6_send_check(struct sk_buff *skb,
+ struct in6_addr *saddr,
+ struct in6_addr *daddr);

static const struct inet_connection_sock_af_ops ipv6_mapped;
static const struct inet_connection_sock_af_ops ipv6_specific;
@@ -503,11 +506,7 @@ static int tcp_v6_send_synack(struct sock *sk, struct request_sock *req,

skb = tcp_make_synack(sk, dst, req, rvp);
if (skb) {
- struct tcphdr *th = tcp_hdr(skb);
-
- th->check = tcp_v6_check(skb->len,
- &treq->loc_addr, &treq->rmt_addr,
- csum_partial(th, skb->len, skb->csum));
+ __tcp_v6_send_check(skb, &treq->loc_addr, &treq->rmt_addr);

ipv6_addr_copy(&fl.fl6_dst, &treq->rmt_addr);
err = ip6_xmit(sk, skb, &fl, opt, 0);
@@ -918,22 +917,29 @@ static struct timewait_sock_ops tcp6_timewait_sock_ops = {
.twsk_destructor= tcp_twsk_destructor,
};

-static void tcp_v6_send_check(struct sock *sk, int len, struct sk_buff *skb)
+static void __tcp_v6_send_check(struct sk_buff *skb,
+ struct in6_addr *saddr, struct in6_addr *daddr)
{
- struct ipv6_pinfo *np = inet6_sk(sk);
struct tcphdr *th = tcp_hdr(skb);

if (skb->ip_summed == CHECKSUM_PARTIAL) {
- th->check = ~csum_ipv6_magic(&np->saddr, &np->daddr, len, IPPROTO_TCP, 0);
+ th->check = ~tcp_v6_check(skb->len, saddr, daddr, 0);
skb->csum_start = skb_transport_header(skb) - skb->head;
skb->csum_offset = offsetof(struct tcphdr, check);
} else {
- th->check = csum_ipv6_magic(&np->saddr, &np->daddr, len, IPPROTO_TCP,
- csum_partial(th, th->doff<<2,
- skb->csum));
+ th->check = tcp_v6_check(skb->len, saddr, daddr,
+ csum_partial(th, th->doff << 2,
+ skb->csum));
}
}

+static void tcp_v6_send_check(struct sock *sk, int len, struct sk_buff *skb)
+{
+ struct ipv6_pinfo *np = inet6_sk(sk);
+
+ __tcp_v6_send_check(skb, &np->saddr, &np->daddr);
+}
+
static int tcp_v6_gso_send_check(struct sk_buff *skb)
{
struct ipv6hdr *ipv6h;
@@ -946,11 +952,8 @@ static int tcp_v6_gso_send_check(struct sk_buff *skb)
th = tcp_hdr(skb);

th->check = 0;
- th->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr, skb->len,
- IPPROTO_TCP, 0);
- skb->csum_start = skb_transport_header(skb) - skb->head;
- skb->csum_offset = offsetof(struct tcphdr, check);
skb->ip_summed = CHECKSUM_PARTIAL;
+ __tcp_v6_send_check(skb, &ipv6h->saddr, &ipv6h->daddr);
return 0;
}

@@ -1053,9 +1056,7 @@ static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win,
ipv6_addr_copy(&fl.fl6_dst, &ipv6_hdr(skb)->saddr);
ipv6_addr_copy(&fl.fl6_src, &ipv6_hdr(skb)->daddr);

- t1->check = csum_ipv6_magic(&fl.fl6_src, &fl.fl6_dst,
- tot_len, IPPROTO_TCP,
- buff->csum);
+ __tcp_v6_send_check(buff, &fl.fl6_src, &fl.fl6_dst);

fl.proto = IPPROTO_TCP;
fl.oif = inet6_iif(skb);
--
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