Currently in xt_socket, we take advantage of early demuxed sockets
since commit 00028aa37098 ("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 681f130f39e1 ("netfilter: xt_socket:
add XT_SOCKET_NOWILDCARD flag").
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
---
[ Ripped that part out of the original xt_cgroup/xt_socket set, as
I think it's useful as is. Thanks! ]
net/netfilter/xt_socket.c | 96 +++++++++++++++++++++++++----------------------
1 file changed, 51 insertions(+), 45 deletions(-)
diff --git a/net/netfilter/xt_socket.c b/net/netfilter/xt_socket.c
index 895534e..5838cc1 100644
--- a/net/netfilter/xt_socket.c
+++ b/net/netfilter/xt_socket.c
@@ -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);
@@ -159,12 +156,15 @@ 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;
sport = hp->source;
daddr = iph->daddr;
@@ -172,16 +172,17 @@ 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 +198,18 @@ 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 +234,7 @@ 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 +331,26 @@ 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 +358,27 @@ 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 +403,7 @@ 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
--
1.9.3
--
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