[tproxy] [PATCH 02/11] TProxy: add lookup type checks for UDP in nf_tproxy_get_sock_v4()
Balazs Scheidler
bazsi at balabit.hu
Sat Aug 15 14:01:51 CEST 2009
Also, inline this function as the lookup_type is always a literal
and inlineing removes branches performed at runtime.
Signed-off-by: Balazs Scheidler <bazsi at balabit.hu>
---
include/net/netfilter/nf_tproxy_core.h | 116 +++++++++++++++++++++++++++++++-
net/netfilter/nf_tproxy_core.c | 48 -------------
2 files changed, 114 insertions(+), 50 deletions(-)
diff --git a/include/net/netfilter/nf_tproxy_core.h b/include/net/netfilter/nf_tproxy_core.h
index b3a8942..4064f35 100644
--- a/include/net/netfilter/nf_tproxy_core.h
+++ b/include/net/netfilter/nf_tproxy_core.h
@@ -13,11 +13,123 @@
#define NFT_LOOKUP_ESTABLISHED 2
/* look up and get a reference to a matching socket */
-extern struct sock *
+
+
+/* This function is used by the 'TPROXY' target and the 'socket'
+ * match. The following lookups are supported:
+ *
+ * Explicit TProxy target rule
+ * ===========================
+ *
+ * This is used when the user wants to intercept a connection matching
+ * an explicit iptables rule. In this case the sockets are assumed
+ * matching in preference order:
+ *
+ * - match: if there's a fully established connection matching the
+ * _packet_ tuple, it is returned, assuming the redirection
+ * already took place and we process a packet belonging to an
+ * established connection
+ *
+ * - match: if there's a listening socket matching the redirection
+ * (e.g. on-port & on-ip of the connection), it is returned,
+ * regardless if it was bound to 0.0.0.0 or an explicit
+ * address. The reasoning is that if there's an explicit rule, it
+ * does not really matter if the listener is bound to an interface
+ * or to 0. The user already stated that he wants redirection
+ * (since he added the rule).
+ *
+ * "socket" match based redirection (no specific rule)
+ * ===================================================
+ *
+ * There are connections with dynamic endpoints (e.g. FTP data
+ * connection) that the user is unable to add explicit rules
+ * for. These are taken care of by a generic "socket" rule. It is
+ * assumed that the proxy application is trusted to open such
+ * connections without explicit iptables rule (except of course the
+ * generic 'socket' rule). In this case the following sockets are
+ * matched in preference order:
+ *
+ * - match: if there's a fully established connection matching the
+ * _packet_ tuple
+ *
+ * - match: if there's a non-zero bound listener (possibly with a
+ * non-local address) We don't accept zero-bound listeners, since
+ * then local services could intercept traffic going through the
+ * box.
+ *
+ * Please note that there's an overlap between what a TPROXY target
+ * and a socket match will match. Normally if you have both rules the
+ * "socket" match will be the first one, effectively all packets
+ * belonging to established connections going through that one.
+ */
+static inline struct sock *
nf_tproxy_get_sock_v4(struct net *net, const u8 protocol,
const __be32 saddr, const __be32 daddr,
const __be16 sport, const __be16 dport,
- const struct net_device *in, int lookup_type);
+ const struct net_device *in, int lookup_type)
+{
+ struct sock *sk;
+
+ /* look up socket */
+ switch (protocol) {
+ case IPPROTO_TCP:
+ switch (lookup_type) {
+ case NFT_LOOKUP_ANY:
+ sk = __inet_lookup(net, &tcp_hashinfo,
+ saddr, sport, daddr, dport,
+ in->ifindex);
+ break;
+ case NFT_LOOKUP_LISTENER:
+ sk = inet_lookup_listener(net, &tcp_hashinfo,
+ daddr, dport,
+ in->ifindex);
+
+ /* NOTE: we return listeners even if bound to
+ * 0.0.0.0, those are filtered out in
+ * xt_socket, since xt_TPROXY needs 0 bound
+ * listeners too */
+
+ break;
+ case NFT_LOOKUP_ESTABLISHED:
+ sk = inet_lookup_established(net, &tcp_hashinfo,
+ saddr, sport, daddr, dport,
+ in->ifindex);
+ break;
+ default:
+ WARN_ON(1);
+ sk = NULL;
+ break;
+ }
+ break;
+ case IPPROTO_UDP:
+ sk = udp4_lib_lookup(net, saddr, sport, daddr, dport,
+ in->ifindex);
+ if (sk && lookup_type != NFT_LOOKUP_ANY) {
+ int connected = (sk->sk_state == TCP_ESTABLISHED);
+ int wildcard = (inet_sk(sk)->rcv_saddr == 0);
+
+ /* NOTE: we return listeners even if bound to
+ * 0.0.0.0, those are filtered out in
+ * xt_socket, since xt_TPROXY needs 0 bound
+ * listeners too */
+ if ((lookup_type == NFT_LOOKUP_ESTABLISHED && (!connected || wildcard)) ||
+ (lookup_type == NFT_LOOKUP_LISTENER && connected)) {
+ sock_put(sk);
+ sk = NULL;
+ }
+ }
+ break;
+ default:
+ WARN_ON(1);
+ sk = NULL;
+ }
+
+ pr_debug("tproxy socket lookup: proto %u %08x:%u -> %08x:%u, lookup type: %d, sock %p\n",
+ protocol, ntohl(saddr), ntohs(sport), ntohl(daddr), ntohs(dport), lookup_type, sk);
+
+ return sk;
+}
+
static inline void
nf_tproxy_put_sock(struct sock *sk)
diff --git a/net/netfilter/nf_tproxy_core.c b/net/netfilter/nf_tproxy_core.c
index 8589e5e..db65563 100644
--- a/net/netfilter/nf_tproxy_core.c
+++ b/net/netfilter/nf_tproxy_core.c
@@ -18,54 +18,6 @@
#include <net/udp.h>
#include <net/netfilter/nf_tproxy_core.h>
-struct sock *
-nf_tproxy_get_sock_v4(struct net *net, const u8 protocol,
- const __be32 saddr, const __be32 daddr,
- const __be16 sport, const __be16 dport,
- const struct net_device *in, int lookup_type)
-{
- struct sock *sk;
-
- /* look up socket */
- switch (protocol) {
- case IPPROTO_TCP:
- switch (lookup_type) {
- case NFT_LOOKUP_ANY:
- sk = __inet_lookup(net, &tcp_hashinfo,
- saddr, sport, daddr, dport,
- in->ifindex);
- break;
- case NFT_LOOKUP_LISTENER:
- sk = inet_lookup_listener(net, &tcp_hashinfo,
- daddr, dport,
- in->ifindex);
- break;
- case NFT_LOOKUP_ESTABLISHED:
- sk = inet_lookup_established(net, &tcp_hashinfo,
- saddr, sport, daddr, dport,
- in->ifindex);
- break;
- default:
- WARN_ON(1);
- sk = NULL;
- break;
- }
- break;
- case IPPROTO_UDP:
- sk = udp4_lib_lookup(net, saddr, sport, daddr, dport,
- in->ifindex);
- break;
- default:
- WARN_ON(1);
- sk = NULL;
- }
-
- pr_debug("tproxy socket lookup: proto %u %08x:%u -> %08x:%u, lookup type: %d, sock %p\n",
- protocol, ntohl(saddr), ntohs(sport), ntohl(daddr), ntohs(dport), lookup_type, sk);
-
- return sk;
-}
-EXPORT_SYMBOL_GPL(nf_tproxy_get_sock_v4);
static void
nf_tproxy_destructor(struct sk_buff *skb)
--
1.6.0.4
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