netfilter: nf_conntrack_sip: pass data offset to NAT functions

When using TCP multiple SIP messages might be present in a single packet.
A following patch will parse them by setting the dptr to the beginning of
each message. The NAT helper needs to reload the dptr value after mangling
the packet however, so it needs to know the offset of the message to the
beginning of the packet.

Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 44 insertions, 38 deletions

diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
index 0ca2f2b..0ec37d6 100644
--- a/net/netfilter/nf_conntrack_sip.c
+++ b/net/netfilter/nf_conntrack_sip.c
@@ -50,12 +50,13 @@ module_param(sip_direct_media, int, 0600);
 MODULE_PARM_DESC(sip_direct_media, "Expect Media streams between signalling "
 				   "endpoints only (default 1)");
 
-unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb,
+unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb, unsigned int dataoff,
 				const char **dptr,
 				unsigned int *datalen) __read_mostly;
 EXPORT_SYMBOL_GPL(nf_nat_sip_hook);
 
 unsigned int (*nf_nat_sip_expect_hook)(struct sk_buff *skb,
+				       unsigned int dataoff,
 				       const char **dptr,
 				       unsigned int *datalen,
 				       struct nf_conntrack_expect *exp,
@@ -63,17 +64,17 @@ unsigned int (*nf_nat_sip_expect_hook)(struct sk_buff *skb,
 				       unsigned int matchlen) __read_mostly;
 EXPORT_SYMBOL_GPL(nf_nat_sip_expect_hook);
 
-unsigned int (*nf_nat_sdp_addr_hook)(struct sk_buff *skb,
+unsigned int (*nf_nat_sdp_addr_hook)(struct sk_buff *skb, unsigned int dataoff,
 				     const char **dptr,
-				     unsigned int dataoff,
 				     unsigned int *datalen,
+				     unsigned int sdpoff,
 				     enum sdp_header_types type,
 				     enum sdp_header_types term,
 				     const union nf_inet_addr *addr)
 				     __read_mostly;
 EXPORT_SYMBOL_GPL(nf_nat_sdp_addr_hook);
 
-unsigned int (*nf_nat_sdp_port_hook)(struct sk_buff *skb,
+unsigned int (*nf_nat_sdp_port_hook)(struct sk_buff *skb, unsigned int dataoff,
 				     const char **dptr,
 				     unsigned int *datalen,
 				     unsigned int matchoff,
@@ -82,14 +83,15 @@ unsigned int (*nf_nat_sdp_port_hook)(struct sk_buff *skb,
 EXPORT_SYMBOL_GPL(nf_nat_sdp_port_hook);
 
 unsigned int (*nf_nat_sdp_session_hook)(struct sk_buff *skb,
-					const char **dptr,
 					unsigned int dataoff,
+					const char **dptr,
 					unsigned int *datalen,
+					unsigned int sdpoff,
 					const union nf_inet_addr *addr)
 					__read_mostly;
 EXPORT_SYMBOL_GPL(nf_nat_sdp_session_hook);
 
-unsigned int (*nf_nat_sdp_media_hook)(struct sk_buff *skb,
+unsigned int (*nf_nat_sdp_media_hook)(struct sk_buff *skb, unsigned int dataoff,
 				      const char **dptr,
 				      unsigned int *datalen,
 				      struct nf_conntrack_expect *rtp_exp,
@@ -729,7 +731,7 @@ static void flush_expectations(struct nf_conn *ct, bool media)
 	spin_unlock_bh(&nf_conntrack_lock);
 }
 
-static int set_expected_rtp_rtcp(struct sk_buff *skb,
+static int set_expected_rtp_rtcp(struct sk_buff *skb, unsigned int dataoff,
 				 const char **dptr, unsigned int *datalen,
 				 union nf_inet_addr *daddr, __be16 port,
 				 enum sip_expectation_classes class,
@@ -806,7 +808,7 @@ static int set_expected_rtp_rtcp(struct sk_buff *skb,
 	if (direct_rtp) {
 		nf_nat_sdp_port = rcu_dereference(nf_nat_sdp_port_hook);
 		if (nf_nat_sdp_port &&
-		    !nf_nat_sdp_port(skb, dptr, datalen,
+		    !nf_nat_sdp_port(skb, dataoff, dptr, datalen,
 				     mediaoff, medialen, ntohs(rtp_port)))
 			goto err1;
 	}
@@ -828,7 +830,8 @@ static int set_expected_rtp_rtcp(struct sk_buff *skb,
 
 	nf_nat_sdp_media = rcu_dereference(nf_nat_sdp_media_hook);
 	if (nf_nat_sdp_media && ct->status & IPS_NAT_MASK && !direct_rtp)
-		ret = nf_nat_sdp_media(skb, dptr, datalen, rtp_exp, rtcp_exp,
+		ret = nf_nat_sdp_media(skb, dataoff, dptr, datalen,
+				       rtp_exp, rtcp_exp,
 				       mediaoff, medialen, daddr);
 	else {
 		if (nf_ct_expect_related(rtp_exp) == 0) {
@@ -867,7 +870,7 @@ static const struct sdp_media_type *sdp_media_type(const char *dptr,
 	return NULL;
 }
 
-static int process_sdp(struct sk_buff *skb,
+static int process_sdp(struct sk_buff *skb, unsigned int dataoff,
 		       const char **dptr, unsigned int *datalen,
 		       unsigned int cseq)
 {
@@ -942,7 +945,7 @@ static int process_sdp(struct sk_buff *skb,
 		else
 			return NF_DROP;
 
-		ret = set_expected_rtp_rtcp(skb, dptr, datalen,
+		ret = set_expected_rtp_rtcp(skb, dataoff, dptr, datalen,
 					    &rtp_addr, htons(port), t->class,
 					    mediaoff, medialen);
 		if (ret != NF_ACCEPT)
@@ -950,8 +953,9 @@ static int process_sdp(struct sk_buff *skb,
 
 		/* Update media connection address if present */
 		if (maddr_len && nf_nat_sdp_addr && ct->status & IPS_NAT_MASK) {
-			ret = nf_nat_sdp_addr(skb, dptr, mediaoff, datalen,
-					      c_hdr, SDP_HDR_MEDIA, &rtp_addr);
+			ret = nf_nat_sdp_addr(skb, dataoff, dptr, datalen,
+					      mediaoff, c_hdr, SDP_HDR_MEDIA,
+					      &rtp_addr);
 			if (ret != NF_ACCEPT)
 				return ret;
 		}
@@ -961,14 +965,15 @@ static int process_sdp(struct sk_buff *skb,
 	/* Update session connection and owner addresses */
 	nf_nat_sdp_session = rcu_dereference(nf_nat_sdp_session_hook);
 	if (nf_nat_sdp_session && ct->status & IPS_NAT_MASK)
-		ret = nf_nat_sdp_session(skb, dptr, sdpoff, datalen, &rtp_addr);
+		ret = nf_nat_sdp_session(skb, dataoff, dptr, datalen, sdpoff,
+					 &rtp_addr);
 
 	if (ret == NF_ACCEPT && i > 0)
 		help->help.ct_sip_info.invite_cseq = cseq;
 
 	return ret;
 }
-static int process_invite_response(struct sk_buff *skb,
+static int process_invite_response(struct sk_buff *skb, unsigned int dataoff,
 				   const char **dptr, unsigned int *datalen,
 				   unsigned int cseq, unsigned int code)
 {
@@ -978,13 +983,13 @@ static int process_invite_response(struct sk_buff *skb,
 
 	if ((code >= 100 && code <= 199) ||
 	    (code >= 200 && code <= 299))
-		return process_sdp(skb, dptr, datalen, cseq);
+		return process_sdp(skb, dataoff, dptr, datalen, cseq);
 	else if (help->help.ct_sip_info.invite_cseq == cseq)
 		flush_expectations(ct, true);
 	return NF_ACCEPT;
 }
 
-static int process_update_response(struct sk_buff *skb,
+static int process_update_response(struct sk_buff *skb, unsigned int dataoff,
 				   const char **dptr, unsigned int *datalen,
 				   unsigned int cseq, unsigned int code)
 {
@@ -994,13 +999,13 @@ static int process_update_response(struct sk_buff *skb,
 
 	if ((code >= 100 && code <= 199) ||
 	    (code >= 200 && code <= 299))
-		return process_sdp(skb, dptr, datalen, cseq);
+		return process_sdp(skb, dataoff, dptr, datalen, cseq);
 	else if (help->help.ct_sip_info.invite_cseq == cseq)
 		flush_expectations(ct, true);
 	return NF_ACCEPT;
 }
 
-static int process_prack_response(struct sk_buff *skb,
+static int process_prack_response(struct sk_buff *skb, unsigned int dataoff,
 				  const char **dptr, unsigned int *datalen,
 				  unsigned int cseq, unsigned int code)
 {
@@ -1010,13 +1015,13 @@ static int process_prack_response(struct sk_buff *skb,
 
 	if ((code >= 100 && code <= 199) ||
 	    (code >= 200 && code <= 299))
-		return process_sdp(skb, dptr, datalen, cseq);
+		return process_sdp(skb, dataoff, dptr, datalen, cseq);
 	else if (help->help.ct_sip_info.invite_cseq == cseq)
 		flush_expectations(ct, true);
 	return NF_ACCEPT;
 }
 
-static int process_bye_request(struct sk_buff *skb,
+static int process_bye_request(struct sk_buff *skb, unsigned int dataoff,
 			       const char **dptr, unsigned int *datalen,
 			       unsigned int cseq)
 {
@@ -1031,7 +1036,7 @@ static int process_bye_request(struct sk_buff *skb,
  * signalling connections. The expectation is marked inactive and is activated
  * when receiving a response indicating success from the registrar.
  */
-static int process_register_request(struct sk_buff *skb,
+static int process_register_request(struct sk_buff *skb, unsigned int dataoff,
 				    const char **dptr, unsigned int *datalen,
 				    unsigned int cseq)
 {
@@ -1101,7 +1106,7 @@ static int process_register_request(struct sk_buff *skb,
 
 	nf_nat_sip_expect = rcu_dereference(nf_nat_sip_expect_hook);
 	if (nf_nat_sip_expect && ct->status & IPS_NAT_MASK)
-		ret = nf_nat_sip_expect(skb, dptr, datalen, exp,
+		ret = nf_nat_sip_expect(skb, dataoff, dptr, datalen, exp,
 					matchoff, matchlen);
 	else {
 		if (nf_ct_expect_related(exp) != 0)
@@ -1117,7 +1122,7 @@ store_cseq:
 	return ret;
 }
 
-static int process_register_response(struct sk_buff *skb,
+static int process_register_response(struct sk_buff *skb, unsigned int dataoff,
 				     const char **dptr, unsigned int *datalen,
 				     unsigned int cseq, unsigned int code)
 {
@@ -1127,7 +1132,7 @@ static int process_register_response(struct sk_buff *skb,
 	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 	union nf_inet_addr addr;
 	__be16 port;
-	unsigned int matchoff, matchlen, dataoff = 0;
+	unsigned int matchoff, matchlen, coff = 0;
 	unsigned int expires = 0;
 	int in_contact = 0, ret;
 
@@ -1154,7 +1159,7 @@ static int process_register_response(struct sk_buff *skb,
 	while (1) {
 		unsigned int c_expires = expires;
 
-		ret = ct_sip_parse_header_uri(ct, *dptr, &dataoff, *datalen,
+		ret = ct_sip_parse_header_uri(ct, *dptr, &coff, *datalen,
 					      SIP_HDR_CONTACT, &in_contact,
 					      &matchoff, &matchlen,
 					      &addr, &port);
@@ -1193,13 +1198,13 @@ static const struct sip_handler sip_handlers[] = {
 	SIP_HANDLER("REGISTER", process_register_request, process_register_response),
 };
 
-static int process_sip_response(struct sk_buff *skb,
+static int process_sip_response(struct sk_buff *skb, unsigned int dataoff,
 				const char **dptr, unsigned int *datalen)
 {
 	enum ip_conntrack_info ctinfo;
 	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
-	unsigned int matchoff, matchlen;
-	unsigned int code, cseq, dataoff, i;
+	unsigned int matchoff, matchlen, matchend;
+	unsigned int code, cseq, i;
 
 	if (*datalen < strlen("SIP/2.0 200"))
 		return NF_ACCEPT;
@@ -1213,7 +1218,7 @@ static int process_sip_response(struct sk_buff *skb,
 	cseq = simple_strtoul(*dptr + matchoff, NULL, 10);
 	if (!cseq)
 		return NF_DROP;
-	dataoff = matchoff + matchlen + 1;
+	matchend = matchoff + matchlen + 1;
 
 	for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) {
 		const struct sip_handler *handler;
@@ -1221,15 +1226,16 @@ static int process_sip_response(struct sk_buff *skb,
 		handler = &sip_handlers[i];
 		if (handler->response == NULL)
 			continue;
-		if (*datalen < dataoff + handler->len ||
-		    strnicmp(*dptr + dataoff, handler->method, handler->len))
+		if (*datalen < matchend + handler->len ||
+		    strnicmp(*dptr + matchend, handler->method, handler->len))
 			continue;
-		return handler->response(skb, dptr, datalen, cseq, code);
+		return handler->response(skb, dataoff, dptr, datalen,
+					 cseq, code);
 	}
 	return NF_ACCEPT;
 }
 
-static int process_sip_request(struct sk_buff *skb,
+static int process_sip_request(struct sk_buff *skb, unsigned int dataoff,
 			       const char **dptr, unsigned int *datalen)
 {
 	enum ip_conntrack_info ctinfo;
@@ -1254,7 +1260,7 @@ static int process_sip_request(struct sk_buff *skb,
 		if (!cseq)
 			return NF_DROP;
 
-		return handler->request(skb, dptr, datalen, cseq);
+		return handler->request(skb, dataoff, dptr, datalen, cseq);
 	}
 	return NF_ACCEPT;
 }
@@ -1288,13 +1294,13 @@ static int sip_help(struct sk_buff *skb,
 		return NF_ACCEPT;
 
 	if (strnicmp(dptr, "SIP/2.0 ", strlen("SIP/2.0 ")) != 0)
-		ret = process_sip_request(skb, &dptr, &datalen);
+		ret = process_sip_request(skb, dataoff, &dptr, &datalen);
 	else
-		ret = process_sip_response(skb, &dptr, &datalen);
+		ret = process_sip_response(skb, dataoff, &dptr, &datalen);
 
 	if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
 		nf_nat_sip = rcu_dereference(nf_nat_sip_hook);
-		if (nf_nat_sip && !nf_nat_sip(skb, &dptr, &datalen))
+		if (nf_nat_sip && !nf_nat_sip(skb, dataoff, &dptr, &datalen))
 			ret = NF_DROP;
 	}