Don't get reserve mtu when user sepcifies the mss through
set-mss.
Signed-off-by: Gao feng <gaofeng@xxxxxxxxxxxxxx>
---
net/netfilter/xt_TCPMSS.c | 70 ++++++++++++++++++++++++-----------------------
1 file changed, 36 insertions(+), 34 deletions(-)
diff --git a/net/netfilter/xt_TCPMSS.c b/net/netfilter/xt_TCPMSS.c
index cd24290..62776de 100644
--- a/net/netfilter/xt_TCPMSS.c
+++ b/net/netfilter/xt_TCPMSS.c
@@ -43,10 +43,41 @@ optlen(const u_int8_t *opt, unsigned int offset)
return opt[offset+1];
}
+static u_int32_t tcpmss_reverse_mtu(const struct sk_buff *skb,
+ unsigned int family)
+{
+ struct flowi fl;
+ const struct nf_afinfo *ai;
+ struct rtable *rt = NULL;
+ u_int32_t mtu = ~0U;
+
+ if (family == PF_INET) {
+ struct flowi4 *fl4 = &fl.u.ip4;
+ memset(fl4, 0, sizeof(*fl4));
+ fl4->daddr = ip_hdr(skb)->saddr;
+ } else {
+ struct flowi6 *fl6 = &fl.u.ip6;
+
+ memset(fl6, 0, sizeof(*fl6));
+ fl6->daddr = ipv6_hdr(skb)->saddr;
+ }
+ rcu_read_lock();
+ ai = nf_get_afinfo(family);
+ if (ai != NULL)
+ ai->route(&init_net, (struct dst_entry **)&rt, &fl, false);
+ rcu_read_unlock();
+
+ if (rt != NULL) {
+ mtu = dst_mtu(&rt->dst);
+ dst_release(&rt->dst);
+ }
+ return mtu;
+}
+
static int
tcpmss_mangle_packet(struct sk_buff *skb,
const struct xt_action_param *par,
- unsigned int in_mtu,
+ unsigned int family,
unsigned int tcphoff,
unsigned int minlen)
{
@@ -76,6 +107,8 @@ tcpmss_mangle_packet(struct sk_buff *skb,
return -1;
if (info->mss == XT_TCPMSS_CLAMP_PMTU) {
+ unsigned int in_mtu = tcpmss_reverse_mtu(skb, family);
+
if (dst_mtu(skb_dst(skb)) <= minlen) {
net_err_ratelimited("unknown or invalid path-MTU (%u)\n",
dst_mtu(skb_dst(skb)));
@@ -165,37 +198,6 @@ tcpmss_mangle_packet(struct sk_buff *skb,
return TCPOLEN_MSS;
}
-static u_int32_t tcpmss_reverse_mtu(const struct sk_buff *skb,
- unsigned int family)
-{
- struct flowi fl;
- const struct nf_afinfo *ai;
- struct rtable *rt = NULL;
- u_int32_t mtu = ~0U;
-
- if (family == PF_INET) {
- struct flowi4 *fl4 = &fl.u.ip4;
- memset(fl4, 0, sizeof(*fl4));
- fl4->daddr = ip_hdr(skb)->saddr;
- } else {
- struct flowi6 *fl6 = &fl.u.ip6;
-
- memset(fl6, 0, sizeof(*fl6));
- fl6->daddr = ipv6_hdr(skb)->saddr;
- }
- rcu_read_lock();
- ai = nf_get_afinfo(family);
- if (ai != NULL)
- ai->route(&init_net, (struct dst_entry **)&rt, &fl, false);
- rcu_read_unlock();
-
- if (rt != NULL) {
- mtu = dst_mtu(&rt->dst);
- dst_release(&rt->dst);
- }
- return mtu;
-}
-
static unsigned int
tcpmss_tg4(struct sk_buff *skb, const struct xt_action_param *par)
{
@@ -204,7 +206,7 @@ tcpmss_tg4(struct sk_buff *skb, const struct xt_action_param *par)
int ret;
ret = tcpmss_mangle_packet(skb, par,
- tcpmss_reverse_mtu(skb, PF_INET),
+ PF_INET,
iph->ihl * 4,
sizeof(*iph) + sizeof(struct tcphdr));
if (ret < 0)
@@ -233,7 +235,7 @@ tcpmss_tg6(struct sk_buff *skb, const struct xt_action_param *par)
if (tcphoff < 0)
return NF_DROP;
ret = tcpmss_mangle_packet(skb, par,
- tcpmss_reverse_mtu(skb, PF_INET6),
+ PF_INET6,
tcphoff,
sizeof(*ipv6h) + sizeof(struct tcphdr));
if (ret < 0)
--
1.8.3.1
--
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