diff options
Diffstat (limited to 'package/rtsp/src/nf_conntrack_rtsp.c')
-rw-r--r-- | package/rtsp/src/nf_conntrack_rtsp.c | 519 |
1 files changed, 519 insertions, 0 deletions
diff --git a/package/rtsp/src/nf_conntrack_rtsp.c b/package/rtsp/src/nf_conntrack_rtsp.c new file mode 100644 index 000000000..c1002aca9 --- /dev/null +++ b/package/rtsp/src/nf_conntrack_rtsp.c @@ -0,0 +1,519 @@ +/* + * RTSP extension for IP connection tracking + * (C) 2003 by Tom Marshall <tmarshall at real.com> + * based on ip_conntrack_irc.c + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + * + * Module load syntax: + * insmod nf_conntrack_rtsp.o ports=port1,port2,...port<MAX_PORTS> + * max_outstanding=n setup_timeout=secs + * + * If no ports are specified, the default will be port 554. + * + * With max_outstanding you can define the maximum number of not yet + * answered SETUP requests per RTSP session (default 8). + * With setup_timeout you can specify how long the system waits for + * an expected data channel (default 300 seconds). + * + * 2005-02-13: Harald Welte <laforge at netfilter.org> + * - port to 2.6 + * - update to recent post-2.6.11 api changes + * 2006-09-14: Steven Van Acker <deepstar at singularity.be> + * - removed calls to NAT code from conntrack helper: NAT no longer needed to use rtsp-conntrack + * 2007-04-18: Michael Guntsche <mike at it-loops.com> + * - Port to new NF API + */ + +#include <linux/module.h> +#include <linux/netfilter.h> +#include <linux/ip.h> +#include <linux/inet.h> +#include <net/tcp.h> + +#include <net/netfilter/nf_conntrack.h> +#include <net/netfilter/nf_conntrack_expect.h> +#include <net/netfilter/nf_conntrack_helper.h> +#include "nf_conntrack_rtsp.h" + +#define NF_NEED_STRNCASECMP +#define NF_NEED_STRTOU16 +#define NF_NEED_STRTOU32 +#define NF_NEED_NEXTLINE +#include "netfilter_helpers.h" +#define NF_NEED_MIME_NEXTLINE +#include "netfilter_mime.h" + +#include <linux/ctype.h> +#define MAX_SIMUL_SETUP 8 /* XXX: use max_outstanding */ + +#define MAX_PORTS 8 +static int ports[MAX_PORTS]; +static int num_ports = 0; +static int max_outstanding = 8; +static unsigned int setup_timeout = 300; + +MODULE_AUTHOR("Tom Marshall <tmarshall at real.com>"); +MODULE_DESCRIPTION("RTSP connection tracking module"); +MODULE_LICENSE("GPL"); +module_param_array(ports, int, &num_ports, 0400); +MODULE_PARM_DESC(ports, "port numbers of RTSP servers"); +module_param(max_outstanding, int, 0400); +MODULE_PARM_DESC(max_outstanding, "max number of outstanding SETUP requests per RTSP session"); +module_param(setup_timeout, int, 0400); +MODULE_PARM_DESC(setup_timeout, "timeout on for unestablished data channels"); + +static char *rtsp_buffer; +static DEFINE_SPINLOCK(rtsp_buffer_lock); + +static struct nf_conntrack_expect_policy rtsp_exp_policy; + +unsigned int (*nf_nat_rtsp_hook)(struct sk_buff *skb, + enum ip_conntrack_info ctinfo, + unsigned int matchoff, unsigned int matchlen,struct ip_ct_rtsp_expect* prtspexp, + struct nf_conntrack_expect *exp); +void (*nf_nat_rtsp_hook_expectfn)(struct nf_conn *ct, struct nf_conntrack_expect *exp); + +EXPORT_SYMBOL_GPL(nf_nat_rtsp_hook); + +/* + * Max mappings we will allow for one RTSP connection (for RTP, the number + * of allocated ports is twice this value). Note that SMIL burns a lot of + * ports so keep this reasonably high. If this is too low, you will see a + * lot of "no free client map entries" messages. + */ +#define MAX_PORT_MAPS 16 + +/*** default port list was here in the masq code: 554, 3030, 4040 ***/ + +#define SKIP_WSPACE(ptr,len,off) while(off < len && isspace(*(ptr+off))) { off++; } + +/* + * Parse an RTSP packet. + * + * Returns zero if parsing failed. + * + * Parameters: + * IN ptcp tcp data pointer + * IN tcplen tcp data len + * IN/OUT ptcpoff points to current tcp offset + * OUT phdrsoff set to offset of rtsp headers + * OUT phdrslen set to length of rtsp headers + * OUT pcseqoff set to offset of CSeq header + * OUT pcseqlen set to length of CSeq header + */ +static int +rtsp_parse_message(char* ptcp, uint tcplen, uint* ptcpoff, + uint* phdrsoff, uint* phdrslen, + uint* pcseqoff, uint* pcseqlen, + uint* transoff, uint* translen) +{ + uint entitylen = 0; + uint lineoff; + uint linelen; + + if (!nf_nextline(ptcp, tcplen, ptcpoff, &lineoff, &linelen)) + return 0; + + *phdrsoff = *ptcpoff; + while (nf_mime_nextline(ptcp, tcplen, ptcpoff, &lineoff, &linelen)) { + if (linelen == 0) { + if (entitylen > 0) + *ptcpoff += min(entitylen, tcplen - *ptcpoff); + break; + } + if (lineoff+linelen > tcplen) { + pr_info("!! overrun !!\n"); + break; + } + + if (nf_strncasecmp(ptcp+lineoff, "CSeq:", 5) == 0) { + *pcseqoff = lineoff; + *pcseqlen = linelen; + } + + if (nf_strncasecmp(ptcp+lineoff, "Transport:", 10) == 0) { + *transoff = lineoff; + *translen = linelen; + } + + if (nf_strncasecmp(ptcp+lineoff, "Content-Length:", 15) == 0) { + uint off = lineoff+15; + SKIP_WSPACE(ptcp+lineoff, linelen, off); + nf_strtou32(ptcp+off, &entitylen); + } + } + *phdrslen = (*ptcpoff) - (*phdrsoff); + + return 1; +} + +/* + * Find lo/hi client ports (if any) in transport header + * In: + * ptcp, tcplen = packet + * tranoff, tranlen = buffer to search + * + * Out: + * pport_lo, pport_hi = lo/hi ports (host endian) + * + * Returns nonzero if any client ports found + * + * Note: it is valid (and expected) for the client to request multiple + * transports, so we need to parse the entire line. + */ +static int +rtsp_parse_transport(char* ptran, uint tranlen, + struct ip_ct_rtsp_expect* prtspexp) +{ + int rc = 0; + uint off = 0; + + if (tranlen < 10 || !iseol(ptran[tranlen-1]) || + nf_strncasecmp(ptran, "Transport:", 10) != 0) { + pr_info("sanity check failed\n"); + return 0; + } + + pr_debug("tran='%.*s'\n", (int)tranlen, ptran); + off += 10; + SKIP_WSPACE(ptran, tranlen, off); + + /* Transport: tran;field;field=val,tran;field;field=val,... */ + while (off < tranlen) { + const char* pparamend; + uint nextparamoff; + + pparamend = memchr(ptran+off, ',', tranlen-off); + pparamend = (pparamend == NULL) ? ptran+tranlen : pparamend+1; + nextparamoff = pparamend-ptran; + + while (off < nextparamoff) { + const char* pfieldend; + uint nextfieldoff; + + pfieldend = memchr(ptran+off, ';', nextparamoff-off); + nextfieldoff = (pfieldend == NULL) ? nextparamoff : pfieldend-ptran+1; + + if (strncmp(ptran+off, "client_port=", 12) == 0) { + u_int16_t port; + uint numlen; + + off += 12; + numlen = nf_strtou16(ptran+off, &port); + off += numlen; + if (prtspexp->loport != 0 && prtspexp->loport != port) + pr_debug("multiple ports found, port %hu ignored\n", port); + else { + pr_debug("lo port found : %hu\n", port); + prtspexp->loport = prtspexp->hiport = port; + if (ptran[off] == '-') { + off++; + numlen = nf_strtou16(ptran+off, &port); + off += numlen; + prtspexp->pbtype = pb_range; + prtspexp->hiport = port; + + // If we have a range, assume rtp: + // loport must be even, hiport must be loport+1 + if ((prtspexp->loport & 0x0001) != 0 || + prtspexp->hiport != prtspexp->loport+1) { + pr_debug("incorrect range: %hu-%hu, correcting\n", + prtspexp->loport, prtspexp->hiport); + prtspexp->loport &= 0xfffe; + prtspexp->hiport = prtspexp->loport+1; + } + } else if (ptran[off] == '/') { + off++; + numlen = nf_strtou16(ptran+off, &port); + off += numlen; + prtspexp->pbtype = pb_discon; + prtspexp->hiport = port; + } + rc = 1; + } + } + + /* + * Note we don't look for the destination parameter here. + * If we are using NAT, the NAT module will handle it. If not, + * and the client is sending packets elsewhere, the expectation + * will quietly time out. + */ + + off = nextfieldoff; + } + + off = nextparamoff; + } + + return rc; +} + +void expected(struct nf_conn *ct, struct nf_conntrack_expect *exp) +{ + typeof(nf_nat_rtsp_hook_expectfn) nf_nat_rtsp_expectfn; + nf_nat_rtsp_expectfn = rcu_dereference(nf_nat_rtsp_hook_expectfn); + if(nf_nat_rtsp_expectfn && ct->master->status & IPS_NAT_MASK) { + nf_nat_rtsp_expectfn(ct,exp); + } +} + +/*** conntrack functions ***/ + +/* outbound packet: client->server */ + +static inline int +help_out(struct sk_buff *skb, unsigned char *rb_ptr, unsigned int datalen, + struct nf_conn *ct, enum ip_conntrack_info ctinfo) +{ + struct ip_ct_rtsp_expect expinfo; + + int dir = CTINFO2DIR(ctinfo); /* = IP_CT_DIR_ORIGINAL */ + //struct tcphdr* tcph = (void*)iph + iph->ihl * 4; + //uint tcplen = pktlen - iph->ihl * 4; + char* pdata = rb_ptr; + //uint datalen = tcplen - tcph->doff * 4; + uint dataoff = 0; + int ret = NF_ACCEPT; + + struct nf_conntrack_expect *exp; + + __be16 be_loport; + + typeof(nf_nat_rtsp_hook) nf_nat_rtsp; + + memset(&expinfo, 0, sizeof(expinfo)); + + while (dataoff < datalen) { + uint cmdoff = dataoff; + uint hdrsoff = 0; + uint hdrslen = 0; + uint cseqoff = 0; + uint cseqlen = 0; + uint transoff = 0; + uint translen = 0; + uint off; + + if (!rtsp_parse_message(pdata, datalen, &dataoff, + &hdrsoff, &hdrslen, + &cseqoff, &cseqlen, + &transoff, &translen)) + break; /* not a valid message */ + + if (strncmp(pdata+cmdoff, "SETUP ", 6) != 0) + continue; /* not a SETUP message */ + pr_debug("found a setup message\n"); + + off = 0; + if(translen) { + rtsp_parse_transport(pdata+transoff, translen, &expinfo); + } + + if (expinfo.loport == 0) { + pr_debug("no udp transports found\n"); + continue; /* no udp transports found */ + } + + pr_debug("udp transport found, ports=(%d,%hu,%hu)\n", + (int)expinfo.pbtype, expinfo.loport, expinfo.hiport); + + exp = nf_ct_expect_alloc(ct); + if (!exp) { + ret = NF_DROP; + goto out; + } + + be_loport = htons(expinfo.loport); + + nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct), + &ct->tuplehash[!dir].tuple.src.u3, &ct->tuplehash[!dir].tuple.dst.u3, + IPPROTO_UDP, NULL, &be_loport); + + exp->master = ct; + + exp->expectfn = expected; + exp->flags = 0; + + if (expinfo.pbtype == pb_range) { + pr_debug("Changing expectation mask to handle multiple ports\n"); + //exp->mask.dst.u.udp.port = 0xfffe; + } + + pr_debug("expect_related %u.%u.%u.%u:%u-%u.%u.%u.%u:%u\n", + NIPQUAD(exp->tuple.src.u3.ip), + ntohs(exp->tuple.src.u.udp.port), + NIPQUAD(exp->tuple.dst.u3.ip), + ntohs(exp->tuple.dst.u.udp.port)); + + nf_nat_rtsp = rcu_dereference(nf_nat_rtsp_hook); + if (nf_nat_rtsp && ct->status & IPS_NAT_MASK) + /* pass the request off to the nat helper */ + ret = nf_nat_rtsp(skb, ctinfo, hdrsoff, hdrslen, &expinfo, exp); + else if (nf_ct_expect_related(exp) != 0) { + pr_info("nf_conntrack_expect_related failed\n"); + ret = NF_DROP; + } + nf_ct_expect_put(exp); + goto out; + } +out: + + return ret; +} + + +static inline int +help_in(struct sk_buff *skb, size_t pktlen, + struct nf_conn* ct, enum ip_conntrack_info ctinfo) +{ + return NF_ACCEPT; +} + +static int help(struct sk_buff *skb, unsigned int protoff, + struct nf_conn *ct, enum ip_conntrack_info ctinfo) +{ + struct tcphdr _tcph, *th; + unsigned int dataoff, datalen; + char *rb_ptr; + int ret = NF_DROP; + + /* Until there's been traffic both ways, don't look in packets. */ + if (ctinfo != IP_CT_ESTABLISHED && + ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) { + pr_debug("conntrackinfo = %u\n", ctinfo); + return NF_ACCEPT; + } + + /* Not whole TCP header? */ + th = skb_header_pointer(skb,protoff, sizeof(_tcph), &_tcph); + + if (!th) + return NF_ACCEPT; + + /* No data ? */ + dataoff = protoff + th->doff*4; + datalen = skb->len - dataoff; + if (dataoff >= skb->len) + return NF_ACCEPT; + + spin_lock_bh(&rtsp_buffer_lock); + rb_ptr = skb_header_pointer(skb, dataoff, + skb->len - dataoff, rtsp_buffer); + BUG_ON(rb_ptr == NULL); + +#if 0 + /* Checksum invalid? Ignore. */ + /* FIXME: Source route IP option packets --RR */ + if (tcp_v4_check(tcph, tcplen, iph->saddr, iph->daddr, + csum_partial((char*)tcph, tcplen, 0))) + { + DEBUGP("bad csum: %p %u %u.%u.%u.%u %u.%u.%u.%u\n", + tcph, tcplen, NIPQUAD(iph->saddr), NIPQUAD(iph->daddr)); + return NF_ACCEPT; + } +#endif + + switch (CTINFO2DIR(ctinfo)) { + case IP_CT_DIR_ORIGINAL: + ret = help_out(skb, rb_ptr, datalen, ct, ctinfo); + break; + case IP_CT_DIR_REPLY: + pr_debug("IP_CT_DIR_REPLY\n"); + /* inbound packet: server->client */ + ret = NF_ACCEPT; + break; + } + + spin_unlock_bh(&rtsp_buffer_lock); + + return ret; +} + +static struct nf_conntrack_helper rtsp_helpers[MAX_PORTS]; +static char rtsp_names[MAX_PORTS][10]; + +/* This function is intentionally _NOT_ defined as __exit */ +static void +fini(void) +{ + int i; + for (i = 0; i < num_ports; i++) { + pr_debug("unregistering port %d\n", ports[i]); + nf_conntrack_helper_unregister(&rtsp_helpers[i]); + } + kfree(rtsp_buffer); +} + +static int __init +init(void) +{ + int i, ret; + struct nf_conntrack_helper *hlpr; + char *tmpname; + + printk("nf_conntrack_rtsp v" IP_NF_RTSP_VERSION " loading\n"); + + if (max_outstanding < 1) { + printk("nf_conntrack_rtsp: max_outstanding must be a positive integer\n"); + return -EBUSY; + } + if (setup_timeout < 0) { + printk("nf_conntrack_rtsp: setup_timeout must be a positive integer\n"); + return -EBUSY; + } + + rtsp_exp_policy.max_expected = max_outstanding; + rtsp_exp_policy.timeout = setup_timeout; + + rtsp_buffer = kmalloc(65536, GFP_KERNEL); + if (!rtsp_buffer) + return -ENOMEM; + + /* If no port given, default to standard rtsp port */ + if (ports[0] == 0) { + ports[0] = RTSP_PORT; + } + + for (i = 0; (i < MAX_PORTS) && ports[i]; i++) { + hlpr = &rtsp_helpers[i]; + memset(hlpr, 0, sizeof(struct nf_conntrack_helper)); + hlpr->tuple.src.l3num = AF_INET; + hlpr->tuple.src.u.tcp.port = htons(ports[i]); + hlpr->tuple.dst.protonum = IPPROTO_TCP; + //hlpr->mask.src.u.tcp.port = 0xFFFF; + //hlpr->mask.dst.protonum = 0xFF; + hlpr->expect_policy = &rtsp_exp_policy; + hlpr->me = THIS_MODULE; + hlpr->help = help; + + tmpname = &rtsp_names[i][0]; + if (ports[i] == RTSP_PORT) { + sprintf(tmpname, "rtsp"); + } else { + sprintf(tmpname, "rtsp-%d", i); + } + hlpr->name = tmpname; + + pr_debug("port #%d: %d\n", i, ports[i]); + + ret = nf_conntrack_helper_register(hlpr); + + if (ret) { + printk("nf_conntrack_rtsp: ERROR registering port %d\n", ports[i]); + fini(); + return -EBUSY; + } + num_ports++; + } + return 0; +} + +module_init(init); +module_exit(fini); + +EXPORT_SYMBOL(nf_nat_rtsp_hook_expectfn); + |