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netfilter: xt_TCPMSS: Get mtu only if clamp-mss-to-pmtu is specified 

This patch refactors the code to skip tcpmss_reverse_mtu if no
clamp-mss-to-pmtu is specified.

Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Gao feng 2013-09-26 15:00:30 +08:00 committed by Pablo Neira Ayuso
parent b21613aeb6
commit de1389b116
1 changed files with 36 additions and 34 deletions
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70
net/netfilter/xt_TCPMSS.c
View File

@ -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)