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netfilter: x_tables: don't extract flow keys on early demuxed sks in socket match 

Currently in xt_socket, we take advantage of early demuxed sockets
since commit 00028aa370 ("netfilter: xt_socket: use IP early demux")
in order to avoid a second socket lookup in the fast path, but we
only make partial use of this:

We still unnecessarily parse headers, extract proto, {s,d}addr and
{s,d}ports from the skb data, accessing possible conntrack information,
etc even though we were not even calling into the socket lookup via
xt_socket_get_sock_{v4,v6}() due to skb->sk hit, meaning those cycles
can be spared.

After this patch, we only proceed the slower, manual lookup path
when we have a skb->sk miss, thus time to match verdict for early
demuxed sockets will improve further, which might be i.e. interesting
for use cases such as mentioned in 681f130f39 ("netfilter: xt_socket:
add XT_SOCKET_NOWILDCARD flag").

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Daniel Borkmann 2015-04-02 14:28:30 +02:00 committed by Pablo Neira Ayuso
parent 0b67c43ce3
commit d64d80a2cd
1 changed files with 50 additions and 45 deletions
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95
net/netfilter/xt_socket.c
View File

@ -143,13 +143,10 @@ static bool xt_socket_sk_is_transparent(struct sock *sk)
}
}
static bool
socket_match(const struct sk_buff *skb, struct xt_action_param *par,
const struct xt_socket_mtinfo1 *info)
static struct sock *xt_socket_lookup_slow_v4(const struct sk_buff *skb,
const struct net_device *indev)
{
const struct iphdr *iph = ip_hdr(skb);
struct udphdr _hdr, *hp = NULL;
struct sock *sk = skb->sk;
__be32 uninitialized_var(daddr), uninitialized_var(saddr);
__be16 uninitialized_var(dport), uninitialized_var(sport);
u8 uninitialized_var(protocol);
@ -159,10 +156,12 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par,
#endif
if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) {
struct udphdr _hdr, *hp;
hp = skb_header_pointer(skb, ip_hdrlen(skb),
sizeof(_hdr), &_hdr);
if (hp == NULL)
return false;
return NULL;
protocol = iph->protocol;
saddr = iph->saddr;
@ -172,16 +171,17 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par,
} else if (iph->protocol == IPPROTO_ICMP) {
if (extract_icmp4_fields(skb, &protocol, &saddr, &daddr,
&sport, &dport))
return false;
&sport, &dport))
return NULL;
} else {
return false;
return NULL;
}
#ifdef XT_SOCKET_HAVE_CONNTRACK
/* Do the lookup with the original socket address in case this is a
* reply packet of an established SNAT-ted connection. */
/* Do the lookup with the original socket address in
* case this is a reply packet of an established
* SNAT-ted connection.
*/
ct = nf_ct_get(skb, &ctinfo);
if (ct && !nf_ct_is_untracked(ct) &&
((iph->protocol != IPPROTO_ICMP &&
@ -197,10 +197,18 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par,
}
#endif
return xt_socket_get_sock_v4(dev_net(skb->dev), protocol, saddr, daddr,
sport, dport, indev);
}
static bool
socket_match(const struct sk_buff *skb, struct xt_action_param *par,
const struct xt_socket_mtinfo1 *info)
{
struct sock *sk = skb->sk;
if (!sk)
sk = xt_socket_get_sock_v4(dev_net(skb->dev), protocol,
saddr, daddr, sport, dport,
par->in);
sk = xt_socket_lookup_slow_v4(skb, par->in);
if (sk) {
bool wildcard;
bool transparent = true;
@ -225,12 +233,7 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par,
sk = NULL;
}
pr_debug("proto %hhu %pI4:%hu -> %pI4:%hu (orig %pI4:%hu) sock %p\n",
protocol, &saddr, ntohs(sport),
&daddr, ntohs(dport),
&iph->daddr, hp ? ntohs(hp->dest) : 0, sk);
return (sk != NULL);
return sk != NULL;
}
static bool
@ -327,28 +330,26 @@ xt_socket_get_sock_v6(struct net *net, const u8 protocol,
return NULL;
}
static bool
socket_mt6_v1_v2(const struct sk_buff *skb, struct xt_action_param *par)
static struct sock *xt_socket_lookup_slow_v6(const struct sk_buff *skb,
const struct net_device *indev)
{
struct ipv6hdr ipv6_var, *iph = ipv6_hdr(skb);
struct udphdr _hdr, *hp = NULL;
struct sock *sk = skb->sk;
const struct in6_addr *daddr = NULL, *saddr = NULL;
__be16 uninitialized_var(dport), uninitialized_var(sport);
int thoff = 0, uninitialized_var(tproto);
const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo;
const struct in6_addr *daddr = NULL, *saddr = NULL;
struct ipv6hdr *iph = ipv6_hdr(skb);
int thoff = 0, tproto;
tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL);
if (tproto < 0) {
pr_debug("unable to find transport header in IPv6 packet, dropping\n");
return NF_DROP;
return NULL;
}
if (tproto == IPPROTO_UDP || tproto == IPPROTO_TCP) {
hp = skb_header_pointer(skb, thoff,
sizeof(_hdr), &_hdr);
struct udphdr _hdr, *hp;
hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr);
if (hp == NULL)
return false;
return NULL;
saddr = &iph->saddr;
sport = hp->source;
@ -356,17 +357,27 @@ socket_mt6_v1_v2(const struct sk_buff *skb, struct xt_action_param *par)
dport = hp->dest;
} else if (tproto == IPPROTO_ICMPV6) {
struct ipv6hdr ipv6_var;
if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr,
&sport, &dport, &ipv6_var))
return false;
return NULL;
} else {
return false;
return NULL;
}
return xt_socket_get_sock_v6(dev_net(skb->dev), tproto, saddr, daddr,
sport, dport, indev);
}
static bool
socket_mt6_v1_v2(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo;
struct sock *sk = skb->sk;
if (!sk)
sk = xt_socket_get_sock_v6(dev_net(skb->dev), tproto,
saddr, daddr, sport, dport,
par->in);
sk = xt_socket_lookup_slow_v6(skb, par->in);
if (sk) {
bool wildcard;
bool transparent = true;
@ -391,13 +402,7 @@ socket_mt6_v1_v2(const struct sk_buff *skb, struct xt_action_param *par)
sk = NULL;
}
pr_debug("proto %hhd %pI6:%hu -> %pI6:%hu "
"(orig %pI6:%hu) sock %p\n",
tproto, saddr, ntohs(sport),
daddr, ntohs(dport),
&iph->daddr, hp ? ntohs(hp->dest) : 0, sk);
return (sk != NULL);
return sk != NULL;
}
#endif