netfilter: nf_conntrack_sip: add TCP support
Add TCP support, which is mandated by RFC3261 for all SIP elements. SIP over TCP is similar to UDP, except that messages are delimited by Content-Length: headers and multiple messages may appear in one packet. Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
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3b6b9fab42
commit
f5b321bd37
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@ -84,7 +84,8 @@ enum sip_header_types {
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SIP_HDR_FROM,
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SIP_HDR_TO,
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SIP_HDR_CONTACT,
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SIP_HDR_VIA,
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SIP_HDR_VIA_UDP,
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SIP_HDR_VIA_TCP,
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SIP_HDR_EXPIRES,
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SIP_HDR_CONTENT_LENGTH,
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};
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@ -122,7 +122,7 @@ static unsigned int ip_nat_sip(struct sk_buff *skb, unsigned int dataoff,
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/* Translate topmost Via header and parameters */
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if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
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SIP_HDR_VIA, NULL, &matchoff, &matchlen,
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SIP_HDR_VIA_UDP, NULL, &matchoff, &matchlen,
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&addr, &port) > 0) {
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unsigned int matchend, poff, plen, buflen, n;
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char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
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@ -16,6 +16,7 @@
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#include <linux/inet.h>
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#include <linux/in.h>
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#include <linux/udp.h>
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#include <linux/tcp.h>
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#include <linux/netfilter.h>
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#include <net/netfilter/nf_conntrack.h>
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@ -287,7 +288,8 @@ static const struct sip_header ct_sip_hdrs[] = {
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[SIP_HDR_FROM] = SIP_HDR("From", "f", "sip:", skp_epaddr_len),
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[SIP_HDR_TO] = SIP_HDR("To", "t", "sip:", skp_epaddr_len),
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[SIP_HDR_CONTACT] = SIP_HDR("Contact", "m", "sip:", skp_epaddr_len),
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[SIP_HDR_VIA] = SIP_HDR("Via", "v", "UDP ", epaddr_len),
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[SIP_HDR_VIA_UDP] = SIP_HDR("Via", "v", "UDP ", epaddr_len),
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[SIP_HDR_VIA_TCP] = SIP_HDR("Via", "v", "TCP ", epaddr_len),
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[SIP_HDR_EXPIRES] = SIP_HDR("Expires", NULL, NULL, digits_len),
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[SIP_HDR_CONTENT_LENGTH] = SIP_HDR("Content-Length", "l", NULL, digits_len),
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};
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@ -519,6 +521,33 @@ int ct_sip_parse_header_uri(const struct nf_conn *ct, const char *dptr,
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}
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EXPORT_SYMBOL_GPL(ct_sip_parse_header_uri);
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static int ct_sip_parse_param(const struct nf_conn *ct, const char *dptr,
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unsigned int dataoff, unsigned int datalen,
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const char *name,
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unsigned int *matchoff, unsigned int *matchlen)
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{
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const char *limit = dptr + datalen;
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const char *start;
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const char *end;
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limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(","));
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if (!limit)
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limit = dptr + datalen;
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start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name));
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if (!start)
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return 0;
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start += strlen(name);
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end = ct_sip_header_search(start, limit, ";", strlen(";"));
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if (!end)
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end = limit;
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*matchoff = start - dptr;
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*matchlen = end - start;
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return 1;
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}
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/* Parse address from header parameter and return address, offset and length */
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int ct_sip_parse_address_param(const struct nf_conn *ct, const char *dptr,
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unsigned int dataoff, unsigned int datalen,
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@ -577,6 +606,29 @@ int ct_sip_parse_numerical_param(const struct nf_conn *ct, const char *dptr,
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}
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EXPORT_SYMBOL_GPL(ct_sip_parse_numerical_param);
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static int ct_sip_parse_transport(struct nf_conn *ct, const char *dptr,
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unsigned int dataoff, unsigned int datalen,
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u8 *proto)
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{
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unsigned int matchoff, matchlen;
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if (ct_sip_parse_param(ct, dptr, dataoff, datalen, "transport=",
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&matchoff, &matchlen)) {
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if (!strnicmp(dptr + matchoff, "TCP", strlen("TCP")))
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*proto = IPPROTO_TCP;
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else if (!strnicmp(dptr + matchoff, "UDP", strlen("UDP")))
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*proto = IPPROTO_UDP;
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else
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return 0;
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if (*proto != nf_ct_protonum(ct))
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return 0;
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} else
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*proto = nf_ct_protonum(ct);
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return 1;
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}
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/* SDP header parsing: a SDP session description contains an ordered set of
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* headers, starting with a section containing general session parameters,
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* optionally followed by multiple media descriptions.
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@ -685,7 +737,7 @@ static int ct_sip_parse_sdp_addr(const struct nf_conn *ct, const char *dptr,
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static int refresh_signalling_expectation(struct nf_conn *ct,
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union nf_inet_addr *addr,
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__be16 port,
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u8 proto, __be16 port,
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unsigned int expires)
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{
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struct nf_conn_help *help = nfct_help(ct);
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@ -697,6 +749,7 @@ static int refresh_signalling_expectation(struct nf_conn *ct,
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hlist_for_each_entry_safe(exp, n, next, &help->expectations, lnode) {
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if (exp->class != SIP_EXPECT_SIGNALLING ||
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!nf_inet_addr_cmp(&exp->tuple.dst.u3, addr) ||
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exp->tuple.dst.protonum != proto ||
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exp->tuple.dst.u.udp.port != port)
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continue;
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if (!del_timer(&exp->timeout))
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@ -1048,6 +1101,7 @@ static int process_register_request(struct sk_buff *skb, unsigned int dataoff,
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struct nf_conntrack_expect *exp;
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union nf_inet_addr *saddr, daddr;
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__be16 port;
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u8 proto;
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unsigned int expires = 0;
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int ret;
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typeof(nf_nat_sip_expect_hook) nf_nat_sip_expect;
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@ -1080,6 +1134,10 @@ static int process_register_request(struct sk_buff *skb, unsigned int dataoff,
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if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, &daddr))
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return NF_ACCEPT;
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if (ct_sip_parse_transport(ct, *dptr, matchoff + matchlen, *datalen,
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&proto) == 0)
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return NF_ACCEPT;
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if (ct_sip_parse_numerical_param(ct, *dptr,
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matchoff + matchlen, *datalen,
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"expires=", NULL, NULL, &expires) < 0)
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@ -1099,7 +1157,7 @@ static int process_register_request(struct sk_buff *skb, unsigned int dataoff,
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saddr = &ct->tuplehash[!dir].tuple.src.u3;
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nf_ct_expect_init(exp, SIP_EXPECT_SIGNALLING, nf_ct_l3num(ct),
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saddr, &daddr, IPPROTO_UDP, NULL, &port);
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saddr, &daddr, proto, NULL, &port);
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exp->timeout.expires = sip_timeout * HZ;
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exp->helper = nfct_help(ct)->helper;
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exp->flags = NF_CT_EXPECT_PERMANENT | NF_CT_EXPECT_INACTIVE;
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@ -1132,6 +1190,7 @@ static int process_register_response(struct sk_buff *skb, unsigned int dataoff,
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enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
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union nf_inet_addr addr;
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__be16 port;
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u8 proto;
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unsigned int matchoff, matchlen, coff = 0;
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unsigned int expires = 0;
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int in_contact = 0, ret;
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@ -1172,6 +1231,10 @@ static int process_register_response(struct sk_buff *skb, unsigned int dataoff,
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if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, &addr))
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continue;
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if (ct_sip_parse_transport(ct, *dptr, matchoff + matchlen,
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*datalen, &proto) == 0)
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continue;
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ret = ct_sip_parse_numerical_param(ct, *dptr,
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matchoff + matchlen,
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*datalen, "expires=",
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@ -1180,7 +1243,8 @@ static int process_register_response(struct sk_buff *skb, unsigned int dataoff,
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return NF_DROP;
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if (c_expires == 0)
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break;
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if (refresh_signalling_expectation(ct, &addr, port, c_expires))
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if (refresh_signalling_expectation(ct, &addr, proto, port,
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c_expires))
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return NF_ACCEPT;
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}
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@ -1265,15 +1329,100 @@ static int process_sip_request(struct sk_buff *skb, unsigned int dataoff,
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return NF_ACCEPT;
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}
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static int sip_help(struct sk_buff *skb,
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unsigned int protoff,
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struct nf_conn *ct,
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enum ip_conntrack_info ctinfo)
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static int process_sip_msg(struct sk_buff *skb, struct nf_conn *ct,
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unsigned int dataoff, const char **dptr,
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unsigned int *datalen)
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{
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typeof(nf_nat_sip_hook) nf_nat_sip;
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int ret;
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if (strnicmp(*dptr, "SIP/2.0 ", strlen("SIP/2.0 ")) != 0)
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ret = process_sip_request(skb, dataoff, dptr, datalen);
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else
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ret = process_sip_response(skb, dataoff, dptr, datalen);
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if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
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nf_nat_sip = rcu_dereference(nf_nat_sip_hook);
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if (nf_nat_sip && !nf_nat_sip(skb, dataoff, dptr, datalen))
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ret = NF_DROP;
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}
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return ret;
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}
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static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff,
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struct nf_conn *ct, enum ip_conntrack_info ctinfo)
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{
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struct tcphdr *th, _tcph;
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unsigned int dataoff, datalen;
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unsigned int matchoff, matchlen, clen;
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unsigned int msglen, origlen;
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const char *dptr, *end;
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s16 diff, tdiff = 0;
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int ret;
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if (ctinfo != IP_CT_ESTABLISHED &&
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ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY)
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return NF_ACCEPT;
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/* No Data ? */
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th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
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if (th == NULL)
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return NF_ACCEPT;
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dataoff = protoff + th->doff * 4;
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if (dataoff >= skb->len)
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return NF_ACCEPT;
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nf_ct_refresh(ct, skb, sip_timeout * HZ);
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if (skb_is_nonlinear(skb)) {
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pr_debug("Copy of skbuff not supported yet.\n");
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return NF_ACCEPT;
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}
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dptr = skb->data + dataoff;
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datalen = skb->len - dataoff;
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if (datalen < strlen("SIP/2.0 200"))
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return NF_ACCEPT;
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while (1) {
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if (ct_sip_get_header(ct, dptr, 0, datalen,
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SIP_HDR_CONTENT_LENGTH,
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&matchoff, &matchlen) <= 0)
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break;
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clen = simple_strtoul(dptr + matchoff, (char **)&end, 10);
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if (dptr + matchoff == end)
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break;
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if (end + strlen("\r\n\r\n") > dptr + datalen)
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break;
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if (end[0] != '\r' || end[1] != '\n' ||
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end[2] != '\r' || end[3] != '\n')
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break;
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end += strlen("\r\n\r\n") + clen;
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msglen = origlen = end - dptr;
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ret = process_sip_msg(skb, ct, dataoff, &dptr, &msglen);
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if (ret != NF_ACCEPT)
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break;
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diff = msglen - origlen;
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tdiff += diff;
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dataoff += msglen;
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dptr += msglen;
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datalen = datalen + diff - msglen;
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}
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return ret;
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}
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static int sip_help_udp(struct sk_buff *skb, unsigned int protoff,
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struct nf_conn *ct, enum ip_conntrack_info ctinfo)
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{
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unsigned int dataoff, datalen;
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const char *dptr;
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int ret;
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typeof(nf_nat_sip_hook) nf_nat_sip;
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/* No Data ? */
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dataoff = protoff + sizeof(struct udphdr);
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@ -1282,33 +1431,21 @@ static int sip_help(struct sk_buff *skb,
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nf_ct_refresh(ct, skb, sip_timeout * HZ);
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if (!skb_is_nonlinear(skb))
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dptr = skb->data + dataoff;
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else {
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if (skb_is_nonlinear(skb)) {
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pr_debug("Copy of skbuff not supported yet.\n");
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return NF_ACCEPT;
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}
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dptr = skb->data + dataoff;
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datalen = skb->len - dataoff;
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if (datalen < strlen("SIP/2.0 200"))
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return NF_ACCEPT;
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if (strnicmp(dptr, "SIP/2.0 ", strlen("SIP/2.0 ")) != 0)
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ret = process_sip_request(skb, dataoff, &dptr, &datalen);
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else
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ret = process_sip_response(skb, dataoff, &dptr, &datalen);
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if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
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nf_nat_sip = rcu_dereference(nf_nat_sip_hook);
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if (nf_nat_sip && !nf_nat_sip(skb, dataoff, &dptr, &datalen))
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ret = NF_DROP;
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}
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return ret;
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return process_sip_msg(skb, ct, dataoff, &dptr, &datalen);
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}
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static struct nf_conntrack_helper sip[MAX_PORTS][2] __read_mostly;
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static char sip_names[MAX_PORTS][2][sizeof("sip-65535")] __read_mostly;
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static struct nf_conntrack_helper sip[MAX_PORTS][4] __read_mostly;
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static char sip_names[MAX_PORTS][4][sizeof("sip-65535")] __read_mostly;
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static const struct nf_conntrack_expect_policy sip_exp_policy[SIP_EXPECT_MAX + 1] = {
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[SIP_EXPECT_SIGNALLING] = {
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@ -1333,7 +1470,7 @@ static void nf_conntrack_sip_fini(void)
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int i, j;
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for (i = 0; i < ports_c; i++) {
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for (j = 0; j < 2; j++) {
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for (j = 0; j < ARRAY_SIZE(sip[i]); j++) {
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if (sip[i][j].me == NULL)
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continue;
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nf_conntrack_helper_unregister(&sip[i][j]);
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@ -1353,14 +1490,24 @@ static int __init nf_conntrack_sip_init(void)
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memset(&sip[i], 0, sizeof(sip[i]));
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sip[i][0].tuple.src.l3num = AF_INET;
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sip[i][1].tuple.src.l3num = AF_INET6;
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for (j = 0; j < 2; j++) {
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sip[i][j].tuple.dst.protonum = IPPROTO_UDP;
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sip[i][0].tuple.dst.protonum = IPPROTO_UDP;
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sip[i][0].help = sip_help_udp;
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sip[i][1].tuple.src.l3num = AF_INET;
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sip[i][1].tuple.dst.protonum = IPPROTO_TCP;
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sip[i][1].help = sip_help_tcp;
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sip[i][2].tuple.src.l3num = AF_INET6;
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sip[i][2].tuple.dst.protonum = IPPROTO_UDP;
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sip[i][2].help = sip_help_udp;
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sip[i][3].tuple.src.l3num = AF_INET6;
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sip[i][3].tuple.dst.protonum = IPPROTO_TCP;
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sip[i][3].help = sip_help_tcp;
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for (j = 0; j < ARRAY_SIZE(sip[i]); j++) {
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sip[i][j].tuple.src.u.udp.port = htons(ports[i]);
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sip[i][j].expect_policy = sip_exp_policy;
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sip[i][j].expect_class_max = SIP_EXPECT_MAX;
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sip[i][j].me = THIS_MODULE;
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sip[i][j].help = sip_help;
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tmpname = &sip_names[i][j][0];
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if (ports[i] == SIP_PORT)
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