[net-next-2.6.git] / net / netfilter / nf_conntrack_sip.c

/* SIP extension for IP connection tracking.
 *
 * (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar>
 * based on RR's ip_conntrack_ftp.c and other modules.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/ctype.h>
#include <linux/skbuff.h>
#include <linux/inet.h>
#include <linux/in.h>
#include <linux/udp.h>
#include <linux/netfilter.h>

#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <linux/netfilter/nf_conntrack_sip.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
MODULE_DESCRIPTION("SIP connection tracking helper");
MODULE_ALIAS("ip_conntrack_sip");

#define MAX_PORTS	8
static unsigned short ports[MAX_PORTS];
static int ports_c;
module_param_array(ports, ushort, &ports_c, 0400);
MODULE_PARM_DESC(ports, "port numbers of SIP servers");

static unsigned int sip_timeout __read_mostly = SIP_TIMEOUT;
module_param(sip_timeout, uint, 0600);
MODULE_PARM_DESC(sip_timeout, "timeout for the master SIP session");

unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb,
				enum ip_conntrack_info ctinfo,
				struct nf_conn *ct,
				const char **dptr) __read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_sip_hook);

unsigned int (*nf_nat_sdp_hook)(struct sk_buff *skb,
				enum ip_conntrack_info ctinfo,
				struct nf_conntrack_expect *exp,
				const char *dptr) __read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_sdp_hook);

static int digits_len(struct nf_conn *, const char *, const char *, int *);
static int epaddr_len(struct nf_conn *, const char *, const char *, int *);
static int skp_digits_len(struct nf_conn *, const char *, const char *, int *);
static int skp_epaddr_len(struct nf_conn *, const char *, const char *, int *);

struct sip_header_nfo {
	const char	*lname;
	const char	*sname;
	const char	*ln_str;
	size_t		lnlen;
	size_t		snlen;
	size_t		ln_strlen;
	int		case_sensitive;
	int		(*match_len)(struct nf_conn *, const char *,
				     const char *, int *);
};

static const struct sip_header_nfo ct_sip_hdrs[] = {
	[POS_REG_REQ_URI] = { 	/* SIP REGISTER request URI */
		.lname		= "sip:",
		.lnlen		= sizeof("sip:") - 1,
		.ln_str		= ":",
		.ln_strlen	= sizeof(":") - 1,
		.match_len	= epaddr_len,
	},
	[POS_REQ_URI] = { 	/* SIP request URI */
		.lname		= "sip:",
		.lnlen		= sizeof("sip:") - 1,
		.ln_str		= "@",
		.ln_strlen	= sizeof("@") - 1,
		.match_len	= epaddr_len,
	},
	[POS_FROM] = {		/* SIP From header */
		.lname		= "From:",
		.lnlen		= sizeof("From:") - 1,
		.sname		= "\r\nf:",
		.snlen		= sizeof("\r\nf:") - 1,
		.ln_str		= "sip:",
		.ln_strlen	= sizeof("sip:") - 1,
		.match_len	= skp_epaddr_len,
	},
	[POS_TO] = {		/* SIP To header */
		.lname		= "To:",
		.lnlen		= sizeof("To:") - 1,
		.sname		= "\r\nt:",
		.snlen		= sizeof("\r\nt:") - 1,
		.ln_str		= "sip:",
		.ln_strlen	= sizeof("sip:") - 1,
		.match_len	= skp_epaddr_len
	},
	[POS_VIA] = { 		/* SIP Via header */
		.lname		= "Via:",
		.lnlen		= sizeof("Via:") - 1,
		.sname		= "\r\nv:",
		.snlen		= sizeof("\r\nv:") - 1, /* rfc3261 "\r\n" */
		.ln_str		= "UDP ",
		.ln_strlen	= sizeof("UDP ") - 1,
		.match_len	= epaddr_len,
	},
	[POS_CONTACT] = { 	/* SIP Contact header */
		.lname		= "Contact:",
		.lnlen		= sizeof("Contact:") - 1,
		.sname		= "\r\nm:",
		.snlen		= sizeof("\r\nm:") - 1,
		.ln_str		= "sip:",
		.ln_strlen	= sizeof("sip:") - 1,
		.match_len	= skp_epaddr_len
	},
	[POS_CONTENT] = { 	/* SIP Content length header */
		.lname		= "Content-Length:",
		.lnlen		= sizeof("Content-Length:") - 1,
		.sname		= "\r\nl:",
		.snlen		= sizeof("\r\nl:") - 1,
		.ln_str		= ":",
		.ln_strlen	= sizeof(":") - 1,
		.match_len	= skp_digits_len
	},
	[POS_MEDIA] = {		/* SDP media info */
		.case_sensitive	= 1,
		.lname		= "\nm=",
		.lnlen		= sizeof("\nm=") - 1,
		.sname		= "\rm=",
		.snlen		= sizeof("\rm=") - 1,
		.ln_str		= "audio ",
		.ln_strlen	= sizeof("audio ") - 1,
		.match_len	= digits_len
	},
	[POS_OWNER_IP4] = {	/* SDP owner address*/
		.case_sensitive	= 1,
		.lname		= "\no=",
		.lnlen		= sizeof("\no=") - 1,
		.sname		= "\ro=",
		.snlen		= sizeof("\ro=") - 1,
		.ln_str		= "IN IP4 ",
		.ln_strlen	= sizeof("IN IP4 ") - 1,
		.match_len	= epaddr_len
	},
	[POS_CONNECTION_IP4] = {/* SDP connection info */
		.case_sensitive	= 1,
		.lname		= "\nc=",
		.lnlen		= sizeof("\nc=") - 1,
		.sname		= "\rc=",
		.snlen		= sizeof("\rc=") - 1,
		.ln_str		= "IN IP4 ",
		.ln_strlen	= sizeof("IN IP4 ") - 1,
		.match_len	= epaddr_len
	},
	[POS_OWNER_IP6] = {	/* SDP owner address*/
		.case_sensitive	= 1,
		.lname		= "\no=",
		.lnlen		= sizeof("\no=") - 1,
		.sname		= "\ro=",
		.snlen		= sizeof("\ro=") - 1,
		.ln_str		= "IN IP6 ",
		.ln_strlen	= sizeof("IN IP6 ") - 1,
		.match_len	= epaddr_len
	},
	[POS_CONNECTION_IP6] = {/* SDP connection info */
		.case_sensitive	= 1,
		.lname		= "\nc=",
		.lnlen		= sizeof("\nc=") - 1,
		.sname		= "\rc=",
		.snlen		= sizeof("\rc=") - 1,
		.ln_str		= "IN IP6 ",
		.ln_strlen	= sizeof("IN IP6 ") - 1,
		.match_len	= epaddr_len
	},
	[POS_SDP_HEADER] = { 	/* SDP version header */
		.case_sensitive	= 1,
		.lname		= "\nv=",
		.lnlen		= sizeof("\nv=") - 1,
		.sname		= "\rv=",
		.snlen		= sizeof("\rv=") - 1,
		.ln_str		= "=",
		.ln_strlen	= sizeof("=") - 1,
		.match_len	= digits_len
	}
};

/* get line length until first CR or LF seen. */
int ct_sip_lnlen(const char *line, const char *limit)
{
	const char *k = line;

	while ((line <= limit) && (*line == '\r' || *line == '\n'))
		line++;

	while (line <= limit) {
		if (*line == '\r' || *line == '\n')
			break;
		line++;
	}
	return line - k;
}
EXPORT_SYMBOL_GPL(ct_sip_lnlen);

/* Linear string search, case sensitive. */
const char *ct_sip_search(const char *needle, const char *haystack,
			  size_t needle_len, size_t haystack_len,
			  int case_sensitive)
{
	const char *limit = haystack + (haystack_len - needle_len);

	while (haystack <= limit) {
		if (case_sensitive) {
			if (strncmp(haystack, needle, needle_len) == 0)
				return haystack;
		} else {
			if (strnicmp(haystack, needle, needle_len) == 0)
				return haystack;
		}
		haystack++;
	}
	return NULL;
}
EXPORT_SYMBOL_GPL(ct_sip_search);

static int digits_len(struct nf_conn *ct, const char *dptr,
		      const char *limit, int *shift)
{
	int len = 0;
	while (dptr <= limit && isdigit(*dptr)) {
		dptr++;
		len++;
	}
	return len;
}

/* get digits length, skipping blank spaces. */
static int skp_digits_len(struct nf_conn *ct, const char *dptr,
			  const char *limit, int *shift)
{
	for (; dptr <= limit && *dptr == ' '; dptr++)
		(*shift)++;

	return digits_len(ct, dptr, limit, shift);
}

static int parse_addr(struct nf_conn *ct, const char *cp, const char **endp,
		      union nf_inet_addr *addr, const char *limit)
{
	const char *end;
	int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
	int ret = 0;

	switch (family) {
	case AF_INET:
		ret = in4_pton(cp, limit - cp, (u8 *)&addr->ip, -1, &end);
		break;
	case AF_INET6:
		ret = in6_pton(cp, limit - cp, (u8 *)&addr->ip6, -1, &end);
		break;
	default:
		BUG();
	}

	if (ret == 0 || end == cp)
		return 0;
	if (endp)
		*endp = end;
	return 1;
}

/* skip ip address. returns its length. */
static int epaddr_len(struct nf_conn *ct, const char *dptr,
		      const char *limit, int *shift)
{
	union nf_inet_addr addr;
	const char *aux = dptr;

	if (!parse_addr(ct, dptr, &dptr, &addr, limit)) {
		pr_debug("ip: %s parse failed.!\n", dptr);
		return 0;
	}

	/* Port number */
	if (*dptr == ':') {
		dptr++;
		dptr += digits_len(ct, dptr, limit, shift);
	}
	return dptr - aux;
}

/* get address length, skiping user info. */
static int skp_epaddr_len(struct nf_conn *ct, const char *dptr,
			  const char *limit, int *shift)
{
	const char *start = dptr;
	int s = *shift;

	/* Search for @, but stop at the end of the line.
	 * We are inside a sip: URI, so we don't need to worry about
	 * continuation lines. */
	while (dptr <= limit &&
	       *dptr != '@' && *dptr != '\r' && *dptr != '\n') {
		(*shift)++;
		dptr++;
	}

	if (dptr <= limit && *dptr == '@') {
		dptr++;
		(*shift)++;
	} else {
		dptr = start;
		*shift = s;
	}

	return epaddr_len(ct, dptr, limit, shift);
}

/* Returns 0 if not found, -1 error parsing. */
int ct_sip_get_info(struct nf_conn *ct,
		    const char *dptr, size_t dlen,
		    unsigned int *matchoff,
		    unsigned int *matchlen,
		    enum sip_header_pos pos)
{
	const struct sip_header_nfo *hnfo = &ct_sip_hdrs[pos];
	const char *limit, *aux, *k = dptr;
	int shift = 0;

	limit = dptr + (dlen - hnfo->lnlen);

	while (dptr <= limit) {
		if ((strncmp(dptr, hnfo->lname, hnfo->lnlen) != 0) &&
		    (hnfo->sname == NULL ||
		     strncmp(dptr, hnfo->sname, hnfo->snlen) != 0)) {
			dptr++;
			continue;
		}
		aux = ct_sip_search(hnfo->ln_str, dptr, hnfo->ln_strlen,
				    ct_sip_lnlen(dptr, limit),
				    hnfo->case_sensitive);
		if (!aux) {
			pr_debug("'%s' not found in '%s'.\n", hnfo->ln_str,
				 hnfo->lname);
			return -1;
		}
		aux += hnfo->ln_strlen;

		*matchlen = hnfo->match_len(ct, aux, limit, &shift);
		if (!*matchlen)
			return -1;

		*matchoff = (aux - k) + shift;

		pr_debug("%s match succeeded! - len: %u\n", hnfo->lname,
			 *matchlen);
		return 1;
	}
	pr_debug("%s header not found.\n", hnfo->lname);
	return 0;
}
EXPORT_SYMBOL_GPL(ct_sip_get_info);

static int set_expected_rtp(struct sk_buff *skb,
			    struct nf_conn *ct,
			    enum ip_conntrack_info ctinfo,
			    union nf_inet_addr *addr,
			    __be16 port,
			    const char *dptr)
{
	struct nf_conntrack_expect *exp;
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	int family = ct->tuplehash[!dir].tuple.src.l3num;
	int ret;
	typeof(nf_nat_sdp_hook) nf_nat_sdp;

	exp = nf_ct_expect_alloc(ct);
	if (exp == NULL)
		return NF_DROP;
	nf_ct_expect_init(exp, family,
			  &ct->tuplehash[!dir].tuple.src.u3, addr,
			  IPPROTO_UDP, NULL, &port);

	nf_nat_sdp = rcu_dereference(nf_nat_sdp_hook);
	if (nf_nat_sdp && ct->status & IPS_NAT_MASK)
		ret = nf_nat_sdp(skb, ctinfo, exp, dptr);
	else {
		if (nf_ct_expect_related(exp) != 0)
			ret = NF_DROP;
		else
			ret = NF_ACCEPT;
	}
	nf_ct_expect_put(exp);

	return ret;
}

static int sip_help(struct sk_buff *skb,
		    unsigned int protoff,
		    struct nf_conn *ct,
		    enum ip_conntrack_info ctinfo)
{
	int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
	union nf_inet_addr addr;
	unsigned int dataoff, datalen;
	const char *dptr;
	int ret = NF_ACCEPT;
	int matchoff, matchlen;
	u_int16_t port;
	enum sip_header_pos pos;
	typeof(nf_nat_sip_hook) nf_nat_sip;

	/* No Data ? */
	dataoff = protoff + sizeof(struct udphdr);
	if (dataoff >= skb->len)
		return NF_ACCEPT;

	nf_ct_refresh(ct, skb, sip_timeout * HZ);

	if (!skb_is_nonlinear(skb))
		dptr = skb->data + dataoff;
	else {
		pr_debug("Copy of skbuff not supported yet.\n");
		goto out;
	}

	nf_nat_sip = rcu_dereference(nf_nat_sip_hook);
	if (nf_nat_sip && ct->status & IPS_NAT_MASK) {
		if (!nf_nat_sip(skb, ctinfo, ct, &dptr)) {
			ret = NF_DROP;
			goto out;
		}
	}

	datalen = skb->len - dataoff;
	if (datalen < sizeof("SIP/2.0 200") - 1)
		goto out;

	/* RTP info only in some SDP pkts */
	if (memcmp(dptr, "INVITE", sizeof("INVITE") - 1) != 0 &&
	    memcmp(dptr, "UPDATE", sizeof("UPDATE") - 1) != 0 &&
	    memcmp(dptr, "SIP/2.0 180", sizeof("SIP/2.0 180") - 1) != 0 &&
	    memcmp(dptr, "SIP/2.0 183", sizeof("SIP/2.0 183") - 1) != 0 &&
	    memcmp(dptr, "SIP/2.0 200", sizeof("SIP/2.0 200") - 1) != 0) {
		goto out;
	}
	/* Get address and port from SDP packet. */
	pos = family == AF_INET ? POS_CONNECTION_IP4 : POS_CONNECTION_IP6;
	if (ct_sip_get_info(ct, dptr, datalen, &matchoff, &matchlen, pos) > 0) {

		/* We'll drop only if there are parse problems. */
		if (!parse_addr(ct, dptr + matchoff, NULL, &addr,
				dptr + datalen)) {
			ret = NF_DROP;
			goto out;
		}
		if (ct_sip_get_info(ct, dptr, datalen, &matchoff, &matchlen,
				    POS_MEDIA) > 0) {

			port = simple_strtoul(dptr + matchoff, NULL, 10);
			if (port < 1024) {
				ret = NF_DROP;
				goto out;
			}
			ret = set_expected_rtp(skb, ct, ctinfo, &addr,
					       htons(port), dptr);
		}
	}
out:
	return ret;
}

static struct nf_conntrack_helper sip[MAX_PORTS][2] __read_mostly;
static char sip_names[MAX_PORTS][2][sizeof("sip-65535")] __read_mostly;

static void nf_conntrack_sip_fini(void)
{
	int i, j;

	for (i = 0; i < ports_c; i++) {
		for (j = 0; j < 2; j++) {
			if (sip[i][j].me == NULL)
				continue;
			nf_conntrack_helper_unregister(&sip[i][j]);
		}
	}
}

static int __init nf_conntrack_sip_init(void)
{
	int i, j, ret;
	char *tmpname;

	if (ports_c == 0)
		ports[ports_c++] = SIP_PORT;

	for (i = 0; i < ports_c; i++) {
		memset(&sip[i], 0, sizeof(sip[i]));

		sip[i][0].tuple.src.l3num = AF_INET;
		sip[i][1].tuple.src.l3num = AF_INET6;
		for (j = 0; j < 2; j++) {
			sip[i][j].tuple.dst.protonum = IPPROTO_UDP;
			sip[i][j].tuple.src.u.udp.port = htons(ports[i]);
			sip[i][j].max_expected = 2;
			sip[i][j].timeout = 3 * 60; /* 3 minutes */
			sip[i][j].me = THIS_MODULE;
			sip[i][j].help = sip_help;

			tmpname = &sip_names[i][j][0];
			if (ports[i] == SIP_PORT)
				sprintf(tmpname, "sip");
			else
				sprintf(tmpname, "sip-%u", i);
			sip[i][j].name = tmpname;

			pr_debug("port #%u: %u\n", i, ports[i]);

			ret = nf_conntrack_helper_register(&sip[i][j]);
			if (ret) {
				printk("nf_ct_sip: failed to register helper "
				       "for pf: %u port: %u\n",
				       sip[i][j].tuple.src.l3num, ports[i]);
				nf_conntrack_sip_fini();
				return ret;
			}
		}
	}
	return 0;
}

module_init(nf_conntrack_sip_init);
module_exit(nf_conntrack_sip_fini);
Commit	Line	Data
9fafcd7b PM	1	/* SIP extension for IP connection tracking.
	2	*
	3	* (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar>
	4	* based on RR's ip_conntrack_ftp.c and other modules.
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License version 2 as
	8	* published by the Free Software Foundation.
	9	*/
	10
	11	#include <linux/module.h>
	12	#include <linux/ctype.h>
	13	#include <linux/skbuff.h>
	14	#include <linux/inet.h>
	15	#include <linux/in.h>
	16	#include <linux/udp.h>
1863f096	17	#include <linux/netfilter.h>
9fafcd7b PM	18
	19	#include <net/netfilter/nf_conntrack.h>
	20	#include <net/netfilter/nf_conntrack_expect.h>
	21	#include <net/netfilter/nf_conntrack_helper.h>
	22	#include <linux/netfilter/nf_conntrack_sip.h>
	23
9fafcd7b PM	24	MODULE_LICENSE("GPL");
	25	MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
	26	MODULE_DESCRIPTION("SIP connection tracking helper");
	27	MODULE_ALIAS("ip_conntrack_sip");
	28
	29	#define MAX_PORTS 8
	30	static unsigned short ports[MAX_PORTS];
	31	static int ports_c;
	32	module_param_array(ports, ushort, &ports_c, 0400);
	33	MODULE_PARM_DESC(ports, "port numbers of SIP servers");
	34
	35	static unsigned int sip_timeout __read_mostly = SIP_TIMEOUT;
	36	module_param(sip_timeout, uint, 0600);
	37	MODULE_PARM_DESC(sip_timeout, "timeout for the master SIP session");
	38
3db05fea	39	unsigned int (nf_nat_sip_hook)(struct sk_buff skb,
9fafcd7b PM	40	enum ip_conntrack_info ctinfo,
	41	struct nf_conn *ct,
	42	const char **dptr) __read_mostly;
	43	EXPORT_SYMBOL_GPL(nf_nat_sip_hook);
	44
3db05fea	45	unsigned int (nf_nat_sdp_hook)(struct sk_buff skb,
9fafcd7b PM	46	enum ip_conntrack_info ctinfo,
	47	struct nf_conntrack_expect *exp,
	48	const char *dptr) __read_mostly;
	49	EXPORT_SYMBOL_GPL(nf_nat_sdp_hook);
	50
	51	static int digits_len(struct nf_conn , const char , const char , int );
	52	static int epaddr_len(struct nf_conn , const char , const char , int );
	53	static int skp_digits_len(struct nf_conn , const char , const char , int );
	54	static int skp_epaddr_len(struct nf_conn , const char , const char , int );
	55
	56	struct sip_header_nfo {
	57	const char *lname;
	58	const char *sname;
	59	const char *ln_str;
	60	size_t lnlen;
	61	size_t snlen;
	62	size_t ln_strlen;
	63	int case_sensitive;
	64	int (match_len)(struct nf_conn , const char *,
	65	const char , int );
	66	};
	67
	68	static const struct sip_header_nfo ct_sip_hdrs[] = {
	69	[POS_REG_REQ_URI] = { /* SIP REGISTER request URI */
	70	.lname = "sip:",
	71	.lnlen = sizeof("sip:") - 1,
	72	.ln_str = ":",
	73	.ln_strlen = sizeof(":") - 1,
	74	.match_len = epaddr_len,
	75	},
	76	[POS_REQ_URI] = { /* SIP request URI */
	77	.lname = "sip:",
	78	.lnlen = sizeof("sip:") - 1,
	79	.ln_str = "@",
	80	.ln_strlen = sizeof("@") - 1,
	81	.match_len = epaddr_len,
	82	},
	83	[POS_FROM] = { /* SIP From header */
	84	.lname = "From:",
	85	.lnlen = sizeof("From:") - 1,
	86	.sname = "\r\nf:",
	87	.snlen = sizeof("\r\nf:") - 1,
	88	.ln_str = "sip:",
	89	.ln_strlen = sizeof("sip:") - 1,
	90	.match_len = skp_epaddr_len,
	91	},
	92	[POS_TO] = { /* SIP To header */
	93	.lname = "To:",
	94	.lnlen = sizeof("To:") - 1,
	95	.sname = "\r\nt:",
	96	.snlen = sizeof("\r\nt:") - 1,
	97	.ln_str = "sip:",
	98	.ln_strlen = sizeof("sip:") - 1,
	99	.match_len = skp_epaddr_len
	100	},
	101	[POS_VIA] = { /* SIP Via header */
	102	.lname = "Via:",
	103	.lnlen = sizeof("Via:") - 1,
	104	.sname = "\r\nv:",
	105	.snlen = sizeof("\r\nv:") - 1, /* rfc3261 "\r\n" */
	106	.ln_str = "UDP ",
	107	.ln_strlen = sizeof("UDP ") - 1,
	108	.match_len = epaddr_len,
	109	},
110	[POS_CONTACT] = { /* SIP Contact header */
111	.lname = "Contact:",
112	.lnlen = sizeof("Contact:") - 1,
113	.sname = "\r\nm:",
114	.snlen = sizeof("\r\nm:") - 1,
115	.ln_str = "sip:",
116	.ln_strlen = sizeof("sip:") - 1,
117	.match_len = skp_epaddr_len
118	},
119	[POS_CONTENT] = { /* SIP Content length header */
120	.lname = "Content-Length:",
121	.lnlen = sizeof("Content-Length:") - 1,
122	.sname = "\r\nl:",
123	.snlen = sizeof("\r\nl:") - 1,
124	.ln_str = ":",
125	.ln_strlen = sizeof(":") - 1,
126	.match_len = skp_digits_len
127	},
128	[POS_MEDIA] = { /* SDP media info */
129	.case_sensitive = 1,
130	.lname = "\nm=",
131	.lnlen = sizeof("\nm=") - 1,
132	.sname = "\rm=",
133	.snlen = sizeof("\rm=") - 1,
134	.ln_str = "audio ",
135	.ln_strlen = sizeof("audio ") - 1,
136	.match_len = digits_len
137	},
138	[POS_OWNER_IP4] = { /* SDP owner address*/
139	.case_sensitive = 1,
140	.lname = "\no=",
141	.lnlen = sizeof("\no=") - 1,
142	.sname = "\ro=",
143	.snlen = sizeof("\ro=") - 1,
144	.ln_str = "IN IP4 ",
145	.ln_strlen = sizeof("IN IP4 ") - 1,
146	.match_len = epaddr_len
147	},
148	[POS_CONNECTION_IP4] = {/* SDP connection info */
149	.case_sensitive = 1,
150	.lname = "\nc=",
151	.lnlen = sizeof("\nc=") - 1,
152	.sname = "\rc=",
153	.snlen = sizeof("\rc=") - 1,
154	.ln_str = "IN IP4 ",
155	.ln_strlen = sizeof("IN IP4 ") - 1,
156	.match_len = epaddr_len
157	},
158	[POS_OWNER_IP6] = { /* SDP owner address*/
159	.case_sensitive = 1,
160	.lname = "\no=",
161	.lnlen = sizeof("\no=") - 1,
162	.sname = "\ro=",
163	.snlen = sizeof("\ro=") - 1,
164	.ln_str = "IN IP6 ",
165	.ln_strlen = sizeof("IN IP6 ") - 1,
166	.match_len = epaddr_len
167	},
168	[POS_CONNECTION_IP6] = {/* SDP connection info */
169	.case_sensitive = 1,
170	.lname = "\nc=",
171	.lnlen = sizeof("\nc=") - 1,
172	.sname = "\rc=",
173	.snlen = sizeof("\rc=") - 1,
174	.ln_str = "IN IP6 ",
175	.ln_strlen = sizeof("IN IP6 ") - 1,
176	.match_len = epaddr_len
177	},
178	[POS_SDP_HEADER] = { /* SDP version header */
179	.case_sensitive = 1,
180	.lname = "\nv=",
181	.lnlen = sizeof("\nv=") - 1,
182	.sname = "\rv=",
183	.snlen = sizeof("\rv=") - 1,
184	.ln_str = "=",
185	.ln_strlen = sizeof("=") - 1,
186	.match_len = digits_len
187	}
188	};
189
c8238177	190	/* get line length until first CR or LF seen. */
9fafcd7b PM	191	int ct_sip_lnlen(const char line, const char limit)
	192	{
	193	const char *k = line;
	194
	195	while ((line <= limit) && (line == '\r' \|\| line == '\n'))
	196	line++;
	197
	198	while (line <= limit) {
	199	if (line == '\r' \|\| line == '\n')
	200	break;
	201	line++;
	202	}
	203	return line - k;
	204	}
	205	EXPORT_SYMBOL_GPL(ct_sip_lnlen);
	206
	207	/* Linear string search, case sensitive. */
	208	const char ct_sip_search(const char needle, const char *haystack,
	209	size_t needle_len, size_t haystack_len,
	210	int case_sensitive)
	211	{
	212	const char *limit = haystack + (haystack_len - needle_len);
	213
	214	while (haystack <= limit) {
	215	if (case_sensitive) {
	216	if (strncmp(haystack, needle, needle_len) == 0)
	217	return haystack;
	218	} else {
	219	if (strnicmp(haystack, needle, needle_len) == 0)
	220	return haystack;
	221	}
	222	haystack++;
	223	}
	224	return NULL;
	225	}
	226	EXPORT_SYMBOL_GPL(ct_sip_search);
	227
	228	static int digits_len(struct nf_conn ct, const char dptr,
	229	const char limit, int shift)
	230	{
	231	int len = 0;
	232	while (dptr <= limit && isdigit(*dptr)) {
	233	dptr++;
	234	len++;
	235	}
	236	return len;
	237	}
	238
c8238177	239	/* get digits length, skipping blank spaces. */
9fafcd7b PM	240	static int skp_digits_len(struct nf_conn ct, const char dptr,
	241	const char limit, int shift)
	242	{
	243	for (; dptr <= limit && *dptr == ' '; dptr++)
	244	(*shift)++;
	245
	246	return digits_len(ct, dptr, limit, shift);
	247	}
	248
	249	static int parse_addr(struct nf_conn ct, const char cp, const char **endp,
643a2c15	250	union nf_inet_addr addr, const char limit)
9fafcd7b PM	251	{
	252	const char *end;
	253	int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
	254	int ret = 0;
	255
	256	switch (family) {
	257	case AF_INET:
	258	ret = in4_pton(cp, limit - cp, (u8 *)&addr->ip, -1, &end);
	259	break;
	260	case AF_INET6:
	261	ret = in6_pton(cp, limit - cp, (u8 *)&addr->ip6, -1, &end);
	262	break;
	263	default:
	264	BUG();
	265	}
	266
	267	if (ret == 0 \|\| end == cp)
	268	return 0;
	269	if (endp)
	270	*endp = end;
	271	return 1;
	272	}
	273
	274	/* skip ip address. returns its length. */
	275	static int epaddr_len(struct nf_conn ct, const char dptr,
	276	const char limit, int shift)
	277	{
643a2c15	278	union nf_inet_addr addr;
9fafcd7b PM	279	const char *aux = dptr;
	280
	281	if (!parse_addr(ct, dptr, &dptr, &addr, limit)) {
0d53778e	282	pr_debug("ip: %s parse failed.!\n", dptr);
9fafcd7b PM	283	return 0;
	284	}
	285
	286	/* Port number */
	287	if (*dptr == ':') {
	288	dptr++;
	289	dptr += digits_len(ct, dptr, limit, shift);
	290	}
	291	return dptr - aux;
	292	}
	293
	294	/* get address length, skiping user info. */
	295	static int skp_epaddr_len(struct nf_conn ct, const char dptr,
	296	const char limit, int shift)
	297	{
aa584eda	298	const char *start = dptr;
9fafcd7b PM	299	int s = *shift;
9fafcd7b PM	300
7da5bfbb LI	301	/* Search for @, but stop at the end of the line.
	302	* We are inside a sip: URI, so we don't need to worry about
	303	* continuation lines. */
	304	while (dptr <= limit &&
	305	dptr != '@' && dptr != '\r' && *dptr != '\n') {
9fafcd7b	306	(*shift)++;
7da5bfbb LI	307	dptr++;
7da5bfbb LI	308	}
9fafcd7b	309
adcb4711	310	if (dptr <= limit && *dptr == '@') {
9fafcd7b PM	311	dptr++;
9fafcd7b PM	312	(*shift)++;
aa584eda PM	313	} else {
aa584eda PM	314	dptr = start;
9fafcd7b	315	*shift = s;
aa584eda	316	}
9fafcd7b PM	317
	318	return epaddr_len(ct, dptr, limit, shift);
	319	}
	320
	321	/* Returns 0 if not found, -1 error parsing. */
	322	int ct_sip_get_info(struct nf_conn *ct,
	323	const char *dptr, size_t dlen,
	324	unsigned int *matchoff,
	325	unsigned int *matchlen,
	326	enum sip_header_pos pos)
	327	{
	328	const struct sip_header_nfo *hnfo = &ct_sip_hdrs[pos];
	329	const char limit, aux, *k = dptr;
	330	int shift = 0;
	331
	332	limit = dptr + (dlen - hnfo->lnlen);
	333
	334	while (dptr <= limit) {
	335	if ((strncmp(dptr, hnfo->lname, hnfo->lnlen) != 0) &&
465f90a4 PM	336	(hnfo->sname == NULL \|\|
465f90a4 PM	337	strncmp(dptr, hnfo->sname, hnfo->snlen) != 0)) {
9fafcd7b PM	338	dptr++;
	339	continue;
	340	}
	341	aux = ct_sip_search(hnfo->ln_str, dptr, hnfo->ln_strlen,
601e68e1	342	ct_sip_lnlen(dptr, limit),
9fafcd7b PM	343	hnfo->case_sensitive);
9fafcd7b PM	344	if (!aux) {
0d53778e PM	345	pr_debug("'%s' not found in '%s'.\n", hnfo->ln_str,
0d53778e PM	346	hnfo->lname);
9fafcd7b PM	347	return -1;
	348	}
	349	aux += hnfo->ln_strlen;
	350
	351	*matchlen = hnfo->match_len(ct, aux, limit, &shift);
	352	if (!*matchlen)
	353	return -1;
	354
	355	*matchoff = (aux - k) + shift;
	356
0d53778e PM	357	pr_debug("%s match succeeded! - len: %u\n", hnfo->lname,
0d53778e PM	358	*matchlen);
9fafcd7b PM	359	return 1;
9fafcd7b PM	360	}
0d53778e	361	pr_debug("%s header not found.\n", hnfo->lname);
9fafcd7b PM	362	return 0;
	363	}
	364	EXPORT_SYMBOL_GPL(ct_sip_get_info);
	365
3db05fea	366	static int set_expected_rtp(struct sk_buff *skb,
9fafcd7b PM	367	struct nf_conn *ct,
9fafcd7b PM	368	enum ip_conntrack_info ctinfo,
643a2c15	369	union nf_inet_addr *addr,
9fafcd7b PM	370	__be16 port,
	371	const char *dptr)
	372	{
	373	struct nf_conntrack_expect *exp;
	374	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	375	int family = ct->tuplehash[!dir].tuple.src.l3num;
	376	int ret;
	377	typeof(nf_nat_sdp_hook) nf_nat_sdp;
	378
6823645d	379	exp = nf_ct_expect_alloc(ct);
9fafcd7b PM	380	if (exp == NULL)
9fafcd7b PM	381	return NF_DROP;
6823645d PM	382	nf_ct_expect_init(exp, family,
	383	&ct->tuplehash[!dir].tuple.src.u3, addr,
	384	IPPROTO_UDP, NULL, &port);
9fafcd7b PM	385
	386	nf_nat_sdp = rcu_dereference(nf_nat_sdp_hook);
	387	if (nf_nat_sdp && ct->status & IPS_NAT_MASK)
3db05fea	388	ret = nf_nat_sdp(skb, ctinfo, exp, dptr);
9fafcd7b	389	else {
6823645d	390	if (nf_ct_expect_related(exp) != 0)
9fafcd7b PM	391	ret = NF_DROP;
	392	else
	393	ret = NF_ACCEPT;
	394	}
6823645d	395	nf_ct_expect_put(exp);
9fafcd7b PM	396
	397	return ret;
	398	}
	399
3db05fea	400	static int sip_help(struct sk_buff *skb,
9fafcd7b PM	401	unsigned int protoff,
	402	struct nf_conn *ct,
	403	enum ip_conntrack_info ctinfo)
	404	{
	405	int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
643a2c15	406	union nf_inet_addr addr;
9fafcd7b PM	407	unsigned int dataoff, datalen;
	408	const char *dptr;
	409	int ret = NF_ACCEPT;
	410	int matchoff, matchlen;
	411	u_int16_t port;
	412	enum sip_header_pos pos;
	413	typeof(nf_nat_sip_hook) nf_nat_sip;
	414
	415	/* No Data ? */
	416	dataoff = protoff + sizeof(struct udphdr);
3db05fea	417	if (dataoff >= skb->len)
9fafcd7b PM	418	return NF_ACCEPT;
9fafcd7b PM	419
3db05fea	420	nf_ct_refresh(ct, skb, sip_timeout * HZ);
9fafcd7b	421
3db05fea HX	422	if (!skb_is_nonlinear(skb))
3db05fea HX	423	dptr = skb->data + dataoff;
9fafcd7b	424	else {
0d53778e	425	pr_debug("Copy of skbuff not supported yet.\n");
9fafcd7b PM	426	goto out;
	427	}
	428
	429	nf_nat_sip = rcu_dereference(nf_nat_sip_hook);
	430	if (nf_nat_sip && ct->status & IPS_NAT_MASK) {
3db05fea	431	if (!nf_nat_sip(skb, ctinfo, ct, &dptr)) {
9fafcd7b PM	432	ret = NF_DROP;
	433	goto out;
	434	}
	435	}
	436
3db05fea	437	datalen = skb->len - dataoff;
9fafcd7b PM	438	if (datalen < sizeof("SIP/2.0 200") - 1)
	439	goto out;
	440
	441	/* RTP info only in some SDP pkts */
	442	if (memcmp(dptr, "INVITE", sizeof("INVITE") - 1) != 0 &&
d258131a JB	443	memcmp(dptr, "UPDATE", sizeof("UPDATE") - 1) != 0 &&
	444	memcmp(dptr, "SIP/2.0 180", sizeof("SIP/2.0 180") - 1) != 0 &&
	445	memcmp(dptr, "SIP/2.0 183", sizeof("SIP/2.0 183") - 1) != 0 &&
9fafcd7b PM	446	memcmp(dptr, "SIP/2.0 200", sizeof("SIP/2.0 200") - 1) != 0) {
	447	goto out;
	448	}
	449	/* Get address and port from SDP packet. */
	450	pos = family == AF_INET ? POS_CONNECTION_IP4 : POS_CONNECTION_IP6;
	451	if (ct_sip_get_info(ct, dptr, datalen, &matchoff, &matchlen, pos) > 0) {
	452
	453	/* We'll drop only if there are parse problems. */
	454	if (!parse_addr(ct, dptr + matchoff, NULL, &addr,
601e68e1	455	dptr + datalen)) {
9fafcd7b PM	456	ret = NF_DROP;
	457	goto out;
	458	}
	459	if (ct_sip_get_info(ct, dptr, datalen, &matchoff, &matchlen,
601e68e1	460	POS_MEDIA) > 0) {
9fafcd7b PM	461
	462	port = simple_strtoul(dptr + matchoff, NULL, 10);
	463	if (port < 1024) {
	464	ret = NF_DROP;
	465	goto out;
	466	}
3db05fea	467	ret = set_expected_rtp(skb, ct, ctinfo, &addr,
9fafcd7b PM	468	htons(port), dptr);
	469	}
	470	}
	471	out:
	472	return ret;
	473	}
	474
	475	static struct nf_conntrack_helper sip[MAX_PORTS][2] __read_mostly;
	476	static char sip_names[MAX_PORTS][2][sizeof("sip-65535")] __read_mostly;
	477
	478	static void nf_conntrack_sip_fini(void)
	479	{
	480	int i, j;
	481
	482	for (i = 0; i < ports_c; i++) {
	483	for (j = 0; j < 2; j++) {
	484	if (sip[i][j].me == NULL)
	485	continue;
	486	nf_conntrack_helper_unregister(&sip[i][j]);
	487	}
	488	}
	489	}
	490
	491	static int __init nf_conntrack_sip_init(void)
	492	{
	493	int i, j, ret;
	494	char *tmpname;
	495
	496	if (ports_c == 0)
	497	ports[ports_c++] = SIP_PORT;
	498
	499	for (i = 0; i < ports_c; i++) {
	500	memset(&sip[i], 0, sizeof(sip[i]));
	501
	502	sip[i][0].tuple.src.l3num = AF_INET;
	503	sip[i][1].tuple.src.l3num = AF_INET6;
	504	for (j = 0; j < 2; j++) {
	505	sip[i][j].tuple.dst.protonum = IPPROTO_UDP;
	506	sip[i][j].tuple.src.u.udp.port = htons(ports[i]);
9fafcd7b PM	507	sip[i][j].max_expected = 2;
	508	sip[i][j].timeout = 3 * 60; /* 3 minutes */
	509	sip[i][j].me = THIS_MODULE;
	510	sip[i][j].help = sip_help;
	511
	512	tmpname = &sip_names[i][j][0];
	513	if (ports[i] == SIP_PORT)
	514	sprintf(tmpname, "sip");
	515	else
	516	sprintf(tmpname, "sip-%u", i);
	517	sip[i][j].name = tmpname;
	518
0d53778e	519	pr_debug("port #%u: %u\n", i, ports[i]);
9fafcd7b PM	520
	521	ret = nf_conntrack_helper_register(&sip[i][j]);
	522	if (ret) {
	523	printk("nf_ct_sip: failed to register helper "
	524	"for pf: %u port: %u\n",
	525	sip[i][j].tuple.src.l3num, ports[i]);
	526	nf_conntrack_sip_fini();
	527	return ret;
	528	}
	529	}
	530	}
	531	return 0;
	532	}
	533
	534	module_init(nf_conntrack_sip_init);
	535	module_exit(nf_conntrack_sip_fini);