| // SPDX-License-Identifier: GPL-2.0-only |
| /* SIP extension for NAT alteration. |
| * |
| * (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar> |
| * based on RR's ip_nat_ftp.c and other modules. |
| * (C) 2007 United Security Providers |
| * (C) 2007, 2008, 2011, 2012 Patrick McHardy <kaber@trash.net> |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/skbuff.h> |
| #include <linux/inet.h> |
| #include <linux/udp.h> |
| #include <linux/tcp.h> |
| |
| #include <net/netfilter/nf_nat.h> |
| #include <net/netfilter/nf_nat_helper.h> |
| #include <net/netfilter/nf_conntrack_core.h> |
| #include <net/netfilter/nf_conntrack_helper.h> |
| #include <net/netfilter/nf_conntrack_expect.h> |
| #include <net/netfilter/nf_conntrack_seqadj.h> |
| #include <linux/netfilter/nf_conntrack_sip.h> |
| |
| #define NAT_HELPER_NAME "sip" |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>"); |
| MODULE_DESCRIPTION("SIP NAT helper"); |
| MODULE_ALIAS_NF_NAT_HELPER(NAT_HELPER_NAME); |
| |
| static struct nf_conntrack_nat_helper nat_helper_sip = |
| NF_CT_NAT_HELPER_INIT(NAT_HELPER_NAME); |
| |
| static unsigned int mangle_packet(struct sk_buff *skb, unsigned int protoff, |
| unsigned int dataoff, |
| const char **dptr, unsigned int *datalen, |
| unsigned int matchoff, unsigned int matchlen, |
| const char *buffer, unsigned int buflen) |
| { |
| enum ip_conntrack_info ctinfo; |
| struct nf_conn *ct = nf_ct_get(skb, &ctinfo); |
| struct tcphdr *th; |
| unsigned int baseoff; |
| |
| if (nf_ct_protonum(ct) == IPPROTO_TCP) { |
| th = (struct tcphdr *)(skb->data + protoff); |
| baseoff = protoff + th->doff * 4; |
| matchoff += dataoff - baseoff; |
| |
| if (!__nf_nat_mangle_tcp_packet(skb, ct, ctinfo, |
| protoff, matchoff, matchlen, |
| buffer, buflen, false)) |
| return 0; |
| } else { |
| baseoff = protoff + sizeof(struct udphdr); |
| matchoff += dataoff - baseoff; |
| |
| if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, |
| protoff, matchoff, matchlen, |
| buffer, buflen)) |
| return 0; |
| } |
| |
| /* Reload data pointer and adjust datalen value */ |
| *dptr = skb->data + dataoff; |
| *datalen += buflen - matchlen; |
| return 1; |
| } |
| |
| static int sip_sprintf_addr(const struct nf_conn *ct, char *buffer, |
| const union nf_inet_addr *addr, bool delim) |
| { |
| if (nf_ct_l3num(ct) == NFPROTO_IPV4) |
| return sprintf(buffer, "%pI4", &addr->ip); |
| else { |
| if (delim) |
| return sprintf(buffer, "[%pI6c]", &addr->ip6); |
| else |
| return sprintf(buffer, "%pI6c", &addr->ip6); |
| } |
| } |
| |
| static int sip_sprintf_addr_port(const struct nf_conn *ct, char *buffer, |
| const union nf_inet_addr *addr, u16 port) |
| { |
| if (nf_ct_l3num(ct) == NFPROTO_IPV4) |
| return sprintf(buffer, "%pI4:%u", &addr->ip, port); |
| else |
| return sprintf(buffer, "[%pI6c]:%u", &addr->ip6, port); |
| } |
| |
| static int map_addr(struct sk_buff *skb, unsigned int protoff, |
| unsigned int dataoff, |
| const char **dptr, unsigned int *datalen, |
| unsigned int matchoff, unsigned int matchlen, |
| union nf_inet_addr *addr, __be16 port) |
| { |
| enum ip_conntrack_info ctinfo; |
| struct nf_conn *ct = nf_ct_get(skb, &ctinfo); |
| enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
| struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct); |
| char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")]; |
| unsigned int buflen; |
| union nf_inet_addr newaddr; |
| __be16 newport; |
| |
| if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, addr) && |
| ct->tuplehash[dir].tuple.src.u.udp.port == port) { |
| newaddr = ct->tuplehash[!dir].tuple.dst.u3; |
| newport = ct->tuplehash[!dir].tuple.dst.u.udp.port; |
| } else if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, addr) && |
| ct->tuplehash[dir].tuple.dst.u.udp.port == port) { |
| newaddr = ct->tuplehash[!dir].tuple.src.u3; |
| newport = ct_sip_info->forced_dport ? : |
| ct->tuplehash[!dir].tuple.src.u.udp.port; |
| } else |
| return 1; |
| |
| if (nf_inet_addr_cmp(&newaddr, addr) && newport == port) |
| return 1; |
| |
| buflen = sip_sprintf_addr_port(ct, buffer, &newaddr, ntohs(newport)); |
| return mangle_packet(skb, protoff, dataoff, dptr, datalen, |
| matchoff, matchlen, buffer, buflen); |
| } |
| |
| static int map_sip_addr(struct sk_buff *skb, unsigned int protoff, |
| unsigned int dataoff, |
| const char **dptr, unsigned int *datalen, |
| enum sip_header_types type) |
| { |
| enum ip_conntrack_info ctinfo; |
| struct nf_conn *ct = nf_ct_get(skb, &ctinfo); |
| unsigned int matchlen, matchoff; |
| union nf_inet_addr addr; |
| __be16 port; |
| |
| if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen, type, NULL, |
| &matchoff, &matchlen, &addr, &port) <= 0) |
| return 1; |
| return map_addr(skb, protoff, dataoff, dptr, datalen, |
| matchoff, matchlen, &addr, port); |
| } |
| |
| static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff, |
| unsigned int dataoff, |
| const char **dptr, unsigned int *datalen) |
| { |
| enum ip_conntrack_info ctinfo; |
| struct nf_conn *ct = nf_ct_get(skb, &ctinfo); |
| enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
| struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct); |
| unsigned int coff, matchoff, matchlen; |
| enum sip_header_types hdr; |
| union nf_inet_addr addr; |
| __be16 port; |
| int request, in_header; |
| |
| /* Basic rules: requests and responses. */ |
| if (strncasecmp(*dptr, "SIP/2.0", strlen("SIP/2.0")) != 0) { |
| if (ct_sip_parse_request(ct, *dptr, *datalen, |
| &matchoff, &matchlen, |
| &addr, &port) > 0 && |
| !map_addr(skb, protoff, dataoff, dptr, datalen, |
| matchoff, matchlen, &addr, port)) { |
| nf_ct_helper_log(skb, ct, "cannot mangle SIP message"); |
| return NF_DROP; |
| } |
| request = 1; |
| } else |
| request = 0; |
| |
| if (nf_ct_protonum(ct) == IPPROTO_TCP) |
| hdr = SIP_HDR_VIA_TCP; |
| else |
| hdr = SIP_HDR_VIA_UDP; |
| |
| /* Translate topmost Via header and parameters */ |
| if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen, |
| hdr, NULL, &matchoff, &matchlen, |
| &addr, &port) > 0) { |
| unsigned int olen, matchend, poff, plen, buflen, n; |
| char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")]; |
| |
| /* We're only interested in headers related to this |
| * connection */ |
| if (request) { |
| if (!nf_inet_addr_cmp(&addr, |
| &ct->tuplehash[dir].tuple.src.u3) || |
| port != ct->tuplehash[dir].tuple.src.u.udp.port) |
| goto next; |
| } else { |
| if (!nf_inet_addr_cmp(&addr, |
| &ct->tuplehash[dir].tuple.dst.u3) || |
| port != ct->tuplehash[dir].tuple.dst.u.udp.port) |
| goto next; |
| } |
| |
| olen = *datalen; |
| if (!map_addr(skb, protoff, dataoff, dptr, datalen, |
| matchoff, matchlen, &addr, port)) { |
| nf_ct_helper_log(skb, ct, "cannot mangle Via header"); |
| return NF_DROP; |
| } |
| |
| matchend = matchoff + matchlen + *datalen - olen; |
| |
| /* The maddr= parameter (RFC 2361) specifies where to send |
| * the reply. */ |
| if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen, |
| "maddr=", &poff, &plen, |
| &addr, true) > 0 && |
| nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.src.u3) && |
| !nf_inet_addr_cmp(&addr, &ct->tuplehash[!dir].tuple.dst.u3)) { |
| buflen = sip_sprintf_addr(ct, buffer, |
| &ct->tuplehash[!dir].tuple.dst.u3, |
| true); |
| if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, |
| poff, plen, buffer, buflen)) { |
| nf_ct_helper_log(skb, ct, "cannot mangle maddr"); |
| return NF_DROP; |
| } |
| } |
| |
| /* The received= parameter (RFC 2361) contains the address |
| * from which the server received the request. */ |
| if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen, |
| "received=", &poff, &plen, |
| &addr, false) > 0 && |
| nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.dst.u3) && |
| !nf_inet_addr_cmp(&addr, &ct->tuplehash[!dir].tuple.src.u3)) { |
| buflen = sip_sprintf_addr(ct, buffer, |
| &ct->tuplehash[!dir].tuple.src.u3, |
| false); |
| if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, |
| poff, plen, buffer, buflen)) { |
| nf_ct_helper_log(skb, ct, "cannot mangle received"); |
| return NF_DROP; |
| } |
| } |
| |
| /* The rport= parameter (RFC 3581) contains the port number |
| * from which the server received the request. */ |
| if (ct_sip_parse_numerical_param(ct, *dptr, matchend, *datalen, |
| "rport=", &poff, &plen, |
| &n) > 0 && |
| htons(n) == ct->tuplehash[dir].tuple.dst.u.udp.port && |
| htons(n) != ct->tuplehash[!dir].tuple.src.u.udp.port) { |
| __be16 p = ct->tuplehash[!dir].tuple.src.u.udp.port; |
| buflen = sprintf(buffer, "%u", ntohs(p)); |
| if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, |
| poff, plen, buffer, buflen)) { |
| nf_ct_helper_log(skb, ct, "cannot mangle rport"); |
| return NF_DROP; |
| } |
| } |
| } |
| |
| next: |
| /* Translate Contact headers */ |
| coff = 0; |
| in_header = 0; |
| while (ct_sip_parse_header_uri(ct, *dptr, &coff, *datalen, |
| SIP_HDR_CONTACT, &in_header, |
| &matchoff, &matchlen, |
| &addr, &port) > 0) { |
| if (!map_addr(skb, protoff, dataoff, dptr, datalen, |
| matchoff, matchlen, |
| &addr, port)) { |
| nf_ct_helper_log(skb, ct, "cannot mangle contact"); |
| return NF_DROP; |
| } |
| } |
| |
| if (!map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_FROM) || |
| !map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_TO)) { |
| nf_ct_helper_log(skb, ct, "cannot mangle SIP from/to"); |
| return NF_DROP; |
| } |
| |
| /* Mangle destination port for Cisco phones, then fix up checksums */ |
| if (dir == IP_CT_DIR_REPLY && ct_sip_info->forced_dport) { |
| struct udphdr *uh; |
| |
| if (skb_ensure_writable(skb, skb->len)) { |
| nf_ct_helper_log(skb, ct, "cannot mangle packet"); |
| return NF_DROP; |
| } |
| |
| uh = (void *)skb->data + protoff; |
| uh->dest = ct_sip_info->forced_dport; |
| |
| if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, protoff, |
| 0, 0, NULL, 0)) { |
| nf_ct_helper_log(skb, ct, "cannot mangle packet"); |
| return NF_DROP; |
| } |
| } |
| |
| return NF_ACCEPT; |
| } |
| |
| static void nf_nat_sip_seq_adjust(struct sk_buff *skb, unsigned int protoff, |
| s16 off) |
| { |
| enum ip_conntrack_info ctinfo; |
| struct nf_conn *ct = nf_ct_get(skb, &ctinfo); |
| const struct tcphdr *th; |
| |
| if (nf_ct_protonum(ct) != IPPROTO_TCP || off == 0) |
| return; |
| |
| th = (struct tcphdr *)(skb->data + protoff); |
| nf_ct_seqadj_set(ct, ctinfo, th->seq, off); |
| } |
| |
| /* Handles expected signalling connections and media streams */ |
| static void nf_nat_sip_expected(struct nf_conn *ct, |
| struct nf_conntrack_expect *exp) |
| { |
| struct nf_conn_help *help = nfct_help(ct->master); |
| struct nf_conntrack_expect *pair_exp; |
| int range_set_for_snat = 0; |
| struct nf_nat_range2 range; |
| |
| /* This must be a fresh one. */ |
| BUG_ON(ct->status & IPS_NAT_DONE_MASK); |
| |
| /* For DST manip, map port here to where it's expected. */ |
| range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED); |
| range.min_proto = range.max_proto = exp->saved_proto; |
| range.min_addr = range.max_addr = exp->saved_addr; |
| nf_nat_setup_info(ct, &range, NF_NAT_MANIP_DST); |
| |
| /* Do media streams SRC manip according with the parameters |
| * found in the paired expectation. |
| */ |
| if (exp->class != SIP_EXPECT_SIGNALLING) { |
| spin_lock_bh(&nf_conntrack_expect_lock); |
| hlist_for_each_entry(pair_exp, &help->expectations, lnode) { |
| if (pair_exp->tuple.src.l3num == nf_ct_l3num(ct) && |
| pair_exp->tuple.dst.protonum == ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum && |
| nf_inet_addr_cmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3, &pair_exp->saved_addr) && |
| ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.all == pair_exp->saved_proto.all) { |
| range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED); |
| range.min_proto.all = range.max_proto.all = pair_exp->tuple.dst.u.all; |
| range.min_addr = range.max_addr = pair_exp->tuple.dst.u3; |
| range_set_for_snat = 1; |
| break; |
| } |
| } |
| spin_unlock_bh(&nf_conntrack_expect_lock); |
| } |
| |
| /* When no paired expectation has been found, change src to |
| * where master sends to, but only if the connection actually came |
| * from the same source. |
| */ |
| if (!range_set_for_snat && |
| nf_inet_addr_cmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3, |
| &ct->master->tuplehash[exp->dir].tuple.src.u3)) { |
| range.flags = NF_NAT_RANGE_MAP_IPS; |
| range.min_addr = range.max_addr |
| = ct->master->tuplehash[!exp->dir].tuple.dst.u3; |
| range_set_for_snat = 1; |
| } |
| |
| /* Perform SRC manip. */ |
| if (range_set_for_snat) |
| nf_nat_setup_info(ct, &range, NF_NAT_MANIP_SRC); |
| } |
| |
| static unsigned int nf_nat_sip_expect(struct sk_buff *skb, unsigned int protoff, |
| unsigned int dataoff, |
| const char **dptr, unsigned int *datalen, |
| struct nf_conntrack_expect *exp, |
| unsigned int matchoff, |
| unsigned int matchlen) |
| { |
| enum ip_conntrack_info ctinfo; |
| struct nf_conn *ct = nf_ct_get(skb, &ctinfo); |
| enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
| struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct); |
| union nf_inet_addr newaddr; |
| u_int16_t port; |
| __be16 srcport; |
| char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")]; |
| unsigned int buflen; |
| |
| /* Connection will come from reply */ |
| if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, |
| &ct->tuplehash[!dir].tuple.dst.u3)) |
| newaddr = exp->tuple.dst.u3; |
| else |
| newaddr = ct->tuplehash[!dir].tuple.dst.u3; |
| |
| /* If the signalling port matches the connection's source port in the |
| * original direction, try to use the destination port in the opposite |
| * direction. */ |
| srcport = ct_sip_info->forced_dport ? : |
| ct->tuplehash[dir].tuple.src.u.udp.port; |
| if (exp->tuple.dst.u.udp.port == srcport) |
| port = ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port); |
| else |
| port = ntohs(exp->tuple.dst.u.udp.port); |
| |
| exp->saved_addr = exp->tuple.dst.u3; |
| exp->tuple.dst.u3 = newaddr; |
| exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port; |
| exp->dir = !dir; |
| exp->expectfn = nf_nat_sip_expected; |
| |
| port = nf_nat_exp_find_port(exp, port); |
| if (port == 0) { |
| nf_ct_helper_log(skb, ct, "all ports in use for SIP"); |
| return NF_DROP; |
| } |
| |
| if (!nf_inet_addr_cmp(&exp->tuple.dst.u3, &exp->saved_addr) || |
| exp->tuple.dst.u.udp.port != exp->saved_proto.udp.port) { |
| buflen = sip_sprintf_addr_port(ct, buffer, &newaddr, port); |
| if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, |
| matchoff, matchlen, buffer, buflen)) { |
| nf_ct_helper_log(skb, ct, "cannot mangle packet"); |
| goto err; |
| } |
| } |
| return NF_ACCEPT; |
| |
| err: |
| nf_ct_unexpect_related(exp); |
| return NF_DROP; |
| } |
| |
| static int mangle_content_len(struct sk_buff *skb, unsigned int protoff, |
| 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; |
| char buffer[sizeof("65536")]; |
| int buflen, c_len; |
| |
| /* Get actual SDP length */ |
| if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen, |
| SDP_HDR_VERSION, SDP_HDR_UNSPEC, |
| &matchoff, &matchlen) <= 0) |
| return 0; |
| c_len = *datalen - matchoff + strlen("v="); |
| |
| /* Now, update SDP length */ |
| if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CONTENT_LENGTH, |
| &matchoff, &matchlen) <= 0) |
| return 0; |
| |
| buflen = sprintf(buffer, "%u", c_len); |
| return mangle_packet(skb, protoff, dataoff, dptr, datalen, |
| matchoff, matchlen, buffer, buflen); |
| } |
| |
| static int mangle_sdp_packet(struct sk_buff *skb, unsigned int protoff, |
| unsigned int dataoff, |
| const char **dptr, unsigned int *datalen, |
| unsigned int sdpoff, |
| enum sdp_header_types type, |
| enum sdp_header_types term, |
| char *buffer, int buflen) |
| { |
| enum ip_conntrack_info ctinfo; |
| struct nf_conn *ct = nf_ct_get(skb, &ctinfo); |
| unsigned int matchlen, matchoff; |
| |
| if (ct_sip_get_sdp_header(ct, *dptr, sdpoff, *datalen, type, term, |
| &matchoff, &matchlen) <= 0) |
| return -ENOENT; |
| return mangle_packet(skb, protoff, dataoff, dptr, datalen, |
| matchoff, matchlen, buffer, buflen) ? 0 : -EINVAL; |
| } |
| |
| static unsigned int nf_nat_sdp_addr(struct sk_buff *skb, unsigned int protoff, |
| unsigned int dataoff, |
| const char **dptr, unsigned int *datalen, |
| unsigned int sdpoff, |
| enum sdp_header_types type, |
| enum sdp_header_types term, |
| const union nf_inet_addr *addr) |
| { |
| enum ip_conntrack_info ctinfo; |
| struct nf_conn *ct = nf_ct_get(skb, &ctinfo); |
| char buffer[INET6_ADDRSTRLEN]; |
| unsigned int buflen; |
| |
| buflen = sip_sprintf_addr(ct, buffer, addr, false); |
| if (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen, |
| sdpoff, type, term, buffer, buflen)) |
| return 0; |
| |
| return mangle_content_len(skb, protoff, dataoff, dptr, datalen); |
| } |
| |
| static unsigned int nf_nat_sdp_port(struct sk_buff *skb, unsigned int protoff, |
| unsigned int dataoff, |
| const char **dptr, unsigned int *datalen, |
| unsigned int matchoff, |
| unsigned int matchlen, |
| u_int16_t port) |
| { |
| char buffer[sizeof("nnnnn")]; |
| unsigned int buflen; |
| |
| buflen = sprintf(buffer, "%u", port); |
| if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, |
| matchoff, matchlen, buffer, buflen)) |
| return 0; |
| |
| return mangle_content_len(skb, protoff, dataoff, dptr, datalen); |
| } |
| |
| static unsigned int nf_nat_sdp_session(struct sk_buff *skb, unsigned int protoff, |
| unsigned int dataoff, |
| const char **dptr, unsigned int *datalen, |
| unsigned int sdpoff, |
| const union nf_inet_addr *addr) |
| { |
| enum ip_conntrack_info ctinfo; |
| struct nf_conn *ct = nf_ct_get(skb, &ctinfo); |
| char buffer[INET6_ADDRSTRLEN]; |
| unsigned int buflen; |
| |
| /* Mangle session description owner and contact addresses */ |
| buflen = sip_sprintf_addr(ct, buffer, addr, false); |
| if (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen, sdpoff, |
| SDP_HDR_OWNER, SDP_HDR_MEDIA, buffer, buflen)) |
| return 0; |
| |
| switch (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen, sdpoff, |
| SDP_HDR_CONNECTION, SDP_HDR_MEDIA, |
| buffer, buflen)) { |
| case 0: |
| /* |
| * RFC 2327: |
| * |
| * Session description |
| * |
| * c=* (connection information - not required if included in all media) |
| */ |
| case -ENOENT: |
| break; |
| default: |
| return 0; |
| } |
| |
| return mangle_content_len(skb, protoff, dataoff, dptr, datalen); |
| } |
| |
| /* So, this packet has hit the connection tracking matching code. |
| Mangle it, and change the expectation to match the new version. */ |
| static unsigned int nf_nat_sdp_media(struct sk_buff *skb, unsigned int protoff, |
| unsigned int dataoff, |
| const char **dptr, unsigned int *datalen, |
| struct nf_conntrack_expect *rtp_exp, |
| struct nf_conntrack_expect *rtcp_exp, |
| unsigned int mediaoff, |
| unsigned int medialen, |
| union nf_inet_addr *rtp_addr) |
| { |
| enum ip_conntrack_info ctinfo; |
| struct nf_conn *ct = nf_ct_get(skb, &ctinfo); |
| enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
| u_int16_t port; |
| |
| /* Connection will come from reply */ |
| if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, |
| &ct->tuplehash[!dir].tuple.dst.u3)) |
| *rtp_addr = rtp_exp->tuple.dst.u3; |
| else |
| *rtp_addr = ct->tuplehash[!dir].tuple.dst.u3; |
| |
| rtp_exp->saved_addr = rtp_exp->tuple.dst.u3; |
| rtp_exp->tuple.dst.u3 = *rtp_addr; |
| rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port; |
| rtp_exp->dir = !dir; |
| rtp_exp->expectfn = nf_nat_sip_expected; |
| |
| rtcp_exp->saved_addr = rtcp_exp->tuple.dst.u3; |
| rtcp_exp->tuple.dst.u3 = *rtp_addr; |
| rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port; |
| rtcp_exp->dir = !dir; |
| rtcp_exp->expectfn = nf_nat_sip_expected; |
| |
| /* Try to get same pair of ports: if not, try to change them. */ |
| for (port = ntohs(rtp_exp->tuple.dst.u.udp.port); |
| port != 0; port += 2) { |
| int ret; |
| |
| rtp_exp->tuple.dst.u.udp.port = htons(port); |
| ret = nf_ct_expect_related(rtp_exp, |
| NF_CT_EXP_F_SKIP_MASTER); |
| if (ret == -EBUSY) |
| continue; |
| else if (ret < 0) { |
| port = 0; |
| break; |
| } |
| rtcp_exp->tuple.dst.u.udp.port = htons(port + 1); |
| ret = nf_ct_expect_related(rtcp_exp, |
| NF_CT_EXP_F_SKIP_MASTER); |
| if (ret == 0) |
| break; |
| else if (ret == -EBUSY) { |
| nf_ct_unexpect_related(rtp_exp); |
| continue; |
| } else if (ret < 0) { |
| nf_ct_unexpect_related(rtp_exp); |
| port = 0; |
| break; |
| } |
| } |
| |
| if (port == 0) { |
| nf_ct_helper_log(skb, ct, "all ports in use for SDP media"); |
| goto err1; |
| } |
| |
| /* Update media port. */ |
| if (rtp_exp->tuple.dst.u.udp.port != rtp_exp->saved_proto.udp.port && |
| !nf_nat_sdp_port(skb, protoff, dataoff, dptr, datalen, |
| mediaoff, medialen, port)) { |
| nf_ct_helper_log(skb, ct, "cannot mangle SDP message"); |
| goto err2; |
| } |
| |
| return NF_ACCEPT; |
| |
| err2: |
| nf_ct_unexpect_related(rtp_exp); |
| nf_ct_unexpect_related(rtcp_exp); |
| err1: |
| return NF_DROP; |
| } |
| |
| static struct nf_ct_helper_expectfn sip_nat = { |
| .name = "sip", |
| .expectfn = nf_nat_sip_expected, |
| }; |
| |
| static void __exit nf_nat_sip_fini(void) |
| { |
| nf_nat_helper_unregister(&nat_helper_sip); |
| RCU_INIT_POINTER(nf_nat_sip_hooks, NULL); |
| nf_ct_helper_expectfn_unregister(&sip_nat); |
| synchronize_rcu(); |
| } |
| |
| static const struct nf_nat_sip_hooks sip_hooks = { |
| .msg = nf_nat_sip, |
| .seq_adjust = nf_nat_sip_seq_adjust, |
| .expect = nf_nat_sip_expect, |
| .sdp_addr = nf_nat_sdp_addr, |
| .sdp_port = nf_nat_sdp_port, |
| .sdp_session = nf_nat_sdp_session, |
| .sdp_media = nf_nat_sdp_media, |
| }; |
| |
| static int __init nf_nat_sip_init(void) |
| { |
| BUG_ON(nf_nat_sip_hooks != NULL); |
| nf_nat_helper_register(&nat_helper_sip); |
| RCU_INIT_POINTER(nf_nat_sip_hooks, &sip_hooks); |
| nf_ct_helper_expectfn_register(&sip_nat); |
| return 0; |
| } |
| |
| module_init(nf_nat_sip_init); |
| module_exit(nf_nat_sip_fini); |