cregit-Linux how code gets into the kernel

Release 4.11 net/netfilter/nf_conntrack_sip.c

Directory: net/netfilter
/* 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.
 * (C) 2007 United Security Providers
 * (C) 2007, 2008 Patrick McHardy <kaber@trash.net>
 *
 * 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.
 */


#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#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/tcp.h>
#include <linux/netfilter.h>

#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_zones.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");
MODULE_ALIAS_NFCT_HELPER("sip");


#define MAX_PORTS	8

static unsigned short ports[MAX_PORTS];

static unsigned 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");


static int sip_direct_signalling __read_mostly = 1;
module_param(sip_direct_signalling, int, 0600);
MODULE_PARM_DESC(sip_direct_signalling, "expect incoming calls from registrar "
					"only (default 1)");


static int sip_direct_media __read_mostly = 1;
module_param(sip_direct_media, int, 0600);
MODULE_PARM_DESC(sip_direct_media, "Expect Media streams between signalling "
				   "endpoints only (default 1)");


const struct nf_nat_sip_hooks *nf_nat_sip_hooks;

EXPORT_SYMBOL_GPL(nf_nat_sip_hooks);




static int string_len(const struct nf_conn *ct, const char *dptr,
		      const char *limit, int *shift)
{
	int len = 0;

	while (dptr < limit && isalpha(*dptr)) {
		dptr++;
		len++;
	}
	return len;
}


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Patrick McHardy5398.15%266.67%


Jan Engelhardt11.85%133.33%


Total54100.00%3100.00%






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


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Patrick McHardy5398.15%266.67%


Jan Engelhardt11.85%133.33%


Total54100.00%3100.00%






static int iswordc(const char c)
{
	if (isalnum(c) || c == '!' || c == '"' || c == '%' ||
	    (c >= '(' && c <= '+') || c == ':' || c == '<' || c == '>' ||
	    c == '?' || (c >= '[' && c <= ']') || c == '_' || c == '`' ||
	    c == '{' || c == '}' || c == '~' || (c >= '-' && c <= '/') ||
	    c == '\'')
		return 1;
	return 0;
}


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Simon Horman9085.71%150.00%


Marco Angaroni1514.29%150.00%


Total105100.00%2100.00%






static int word_len(const char *dptr, const char *limit)
{
	int len = 0;
	while (dptr < limit && iswordc(*dptr)) {
		dptr++;
		len++;
	}
	return len;
}


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Simon Horman44100.00%1100.00%


Total44100.00%1100.00%






static int callid_len(const struct nf_conn *ct, const char *dptr,
		      const char *limit, int *shift)
{
	int len, domain_len;

	len = word_len(dptr, limit);
	dptr += len;
	if (!len || dptr == limit || *dptr != '@')
		return len;
	dptr++;
	len++;

	domain_len = word_len(dptr, limit);
	if (!domain_len)
		return 0;
	return len + domain_len;
}


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Simon Horman89100.00%1100.00%


Total89100.00%1100.00%



/* get media type + port length */



static int media_len(const struct nf_conn *ct, const char *dptr,
		     const char *limit, int *shift)
{
	int len = string_len(ct, dptr, limit, shift);

	dptr += len;
	if (dptr >= limit || *dptr != ' ')
		return 0;
	len++;
	dptr++;

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


Contributors
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Patrick McHardy78100.00%1100.00%


Total78100.00%1100.00%






static int sip_parse_addr(const struct nf_conn *ct, const char *cp,
			  const char **endp, union nf_inet_addr *addr,
			  const char *limit, bool delim)
{
	const char *end;
	int ret;

	if (!ct)
		return 0;

	memset(addr, 0, sizeof(*addr));
	switch (nf_ct_l3num(ct)) {
	case AF_INET:
		ret = in4_pton(cp, limit - cp, (u8 *)&addr->ip, -1, &end);
		if (ret == 0)
			return 0;
		break;
	case AF_INET6:
		if (cp < limit && *cp == '[')
			cp++;
		else if (delim)
			return 0;

		ret = in6_pton(cp, limit - cp, (u8 *)&addr->ip6, -1, &end);
		if (ret == 0)
			return 0;

		if (end < limit && *end == ']')
			end++;
		else if (delim)
			return 0;
		break;
	default:
		BUG();
	}

	if (endp)
		*endp = end;
	return 1;
}


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Patrick McHardy20395.75%571.43%


Simon Horman83.77%114.29%


Jan Engelhardt10.47%114.29%


Total212100.00%7100.00%



/* skip ip address. returns its length. */



static int epaddr_len(const struct nf_conn *ct, const char *dptr,
		      const char *limit, int *shift)
{
	union nf_inet_addr addr;
	const char *aux = dptr;

	if (!sip_parse_addr(ct, dptr, &dptr, &addr, limit, true)) {
		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;
}


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Patrick McHardy9999.00%480.00%


Jan Engelhardt11.00%120.00%


Total100100.00%5100.00%



/* get address length, skiping user info. */



static int skp_epaddr_len(const 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);
}


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Patrick McHardy11799.15%375.00%


Jan Engelhardt10.85%125.00%


Total118100.00%4100.00%



/* Parse a SIP request line of the form:
 *
 * Request-Line = Method SP Request-URI SP SIP-Version CRLF
 *
 * and return the offset and length of the address contained in the Request-URI.
 */



int ct_sip_parse_request(const struct nf_conn *ct,
			 const char *dptr, unsigned int datalen,
			 unsigned int *matchoff, unsigned int *matchlen,
			 union nf_inet_addr *addr, __be16 *port)
{
	const char *start = dptr, *limit = dptr + datalen, *end;
	unsigned int mlen;
	unsigned int p;
	int shift = 0;

	/* Skip method and following whitespace */
	mlen = string_len(ct, dptr, limit, NULL);
	if (!mlen)
		return 0;
	dptr += mlen;
	if (++dptr >= limit)
		return 0;

	/* Find SIP URI */
	for (; dptr < limit - strlen("sip:"); dptr++) {
		if (*dptr == '\r' || *dptr == '\n')
			return -1;
		if (strncasecmp(dptr, "sip:", strlen("sip:")) == 0) {
			dptr += strlen("sip:");
			break;
		}
	}
	if (!skp_epaddr_len(ct, dptr, limit, &shift))
		return 0;
	dptr += shift;

	if (!sip_parse_addr(ct, dptr, &end, addr, limit, true))
		return -1;
	if (end < limit && *end == ':') {
		end++;
		p = simple_strtoul(end, (char **)&end, 10);
		if (p < 1024 || p > 65535)
			return -1;
		*port = htons(p);
	} else
		*port = htons(SIP_PORT);

	if (end == dptr)
		return 0;
	*matchoff = dptr - start;
	*matchlen = end - dptr;
	return 1;
}

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Patrick McHardy29899.33%675.00%


Jan Engelhardt10.33%112.50%


Rasmus Villemoes10.33%112.50%


Total300100.00%8100.00%




EXPORT_SYMBOL_GPL(ct_sip_parse_request);

/* SIP header parsing: SIP headers are located at the beginning of a line, but
 * may span several lines, in which case the continuation lines begin with a
 * whitespace character. RFC 2543 allows lines to be terminated with CR, LF or
 * CRLF, RFC 3261 allows only CRLF, we support both.
 *
 * Headers are followed by (optionally) whitespace, a colon, again (optionally)
 * whitespace and the values. Whitespace in this context means any amount of
 * tabs, spaces and continuation lines, which are treated as a single whitespace
 * character.
 *
 * Some headers may appear multiple times. A comma separated list of values is
 * equivalent to multiple headers.
 */

static const struct sip_header ct_sip_hdrs[] = {
	[SIP_HDR_CSEQ]			= SIP_HDR("CSeq", NULL, NULL, digits_len),
	[SIP_HDR_FROM]			= SIP_HDR("From", "f", "sip:", skp_epaddr_len),
	[SIP_HDR_TO]			= SIP_HDR("To", "t", "sip:", skp_epaddr_len),
	[SIP_HDR_CONTACT]		= SIP_HDR("Contact", "m", "sip:", skp_epaddr_len),
	[SIP_HDR_VIA_UDP]		= SIP_HDR("Via", "v", "UDP ", epaddr_len),
	[SIP_HDR_VIA_TCP]		= SIP_HDR("Via", "v", "TCP ", epaddr_len),
	[SIP_HDR_EXPIRES]		= SIP_HDR("Expires", NULL, NULL, digits_len),
	[SIP_HDR_CONTENT_LENGTH]	= SIP_HDR("Content-Length", "l", NULL, digits_len),
	[SIP_HDR_CALL_ID]		= SIP_HDR("Call-Id", "i", NULL, callid_len),
};




static const char *sip_follow_continuation(const char *dptr, const char *limit)
{
	/* Walk past newline */
	if (++dptr >= limit)
		return NULL;

	/* Skip '\n' in CR LF */
	if (*(dptr - 1) == '\r' && *dptr == '\n') {
		if (++dptr >= limit)
			return NULL;
	}

	/* Continuation line? */
	if (*dptr != ' ' && *dptr != '\t')
		return NULL;

	/* skip leading whitespace */
	for (; dptr < limit; dptr++) {
		if (*dptr != ' ' && *dptr != '\t')
			break;
	}
	return dptr;
}


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Patrick McHardy103100.00%2100.00%


Total103100.00%2100.00%






static const char *sip_skip_whitespace(const char *dptr, const char *limit)
{
	for (; dptr < limit; dptr++) {
		if (*dptr == ' ' || *dptr == '\t')
			continue;
		if (*dptr != '\r' && *dptr != '\n')
			break;
		dptr = sip_follow_continuation(dptr, limit);
		break;
	}
	return dptr;
}


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Patrick McHardy6391.30%360.00%


Marco Angaroni68.70%240.00%


Total69100.00%5100.00%



/* Search within a SIP header value, dealing with continuation lines */



static const char *ct_sip_header_search(const char *dptr, const char *limit,
					const char *needle, unsigned int len)
{
	for (limit -= len; dptr < limit; dptr++) {
		if (*dptr == '\r' || *dptr == '\n') {
			dptr = sip_follow_continuation(dptr, limit);
			if (dptr == NULL)
				break;
			continue;
		}

		if (strncasecmp(dptr, needle, len) == 0)
			return dptr;
	}
	return NULL;
}


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Patrick McHardy9198.91%266.67%


Rasmus Villemoes11.09%133.33%


Total92100.00%3100.00%






int ct_sip_get_header(const struct nf_conn *ct, const char *dptr,
		      unsigned int dataoff, unsigned int datalen,
		      enum sip_header_types type,
		      unsigned int *matchoff, unsigned int *matchlen)
{
	const struct sip_header *hdr = &ct_sip_hdrs[type];
	const char *start = dptr, *limit = dptr + datalen;
	int shift = 0;

	for (dptr += dataoff; dptr < limit; dptr++) {
		/* Find beginning of line */
		if (*dptr != '\r' && *dptr != '\n')
			continue;
		if (++dptr >= limit)
			break;
		if (*(dptr - 1) == '\r' && *dptr == '\n') {
			if (++dptr >= limit)
				break;
		}

		/* Skip continuation lines */
		if (*dptr == ' ' || *dptr == '\t')
			continue;

		/* Find header. Compact headers must be followed by a
                 * non-alphabetic character to avoid mismatches. */
		if (limit - dptr >= hdr->len &&
		    strncasecmp(dptr, hdr->name, hdr->len) == 0)
			dptr += hdr->len;
		else if (hdr->cname && limit - dptr >= hdr->clen + 1 &&
			 strncasecmp(dptr, hdr->cname, hdr->clen) == 0 &&
			 !isalpha(*(dptr + hdr->clen)))
			dptr += hdr->clen;
		else
			continue;

		/* Find and skip colon */
		dptr = sip_skip_whitespace(dptr, limit);
		if (dptr == NULL)
			break;
		if (*dptr != ':' || ++dptr >= limit)
			break;

		/* Skip whitespace after colon */
		dptr = sip_skip_whitespace(dptr, limit);
		if (dptr == NULL)
			break;

		*matchoff = dptr - start;
		if (hdr->search) {
			dptr = ct_sip_header_search(dptr, limit, hdr->search,
						    hdr->slen);
			if (!dptr)
				return -1;
			dptr += hdr->slen;
		}

		*matchlen = hdr->match_len(ct, dptr, limit, &shift);
		if (!*matchlen)
			return -1;
		*matchoff = dptr - start + shift;
		return 1;
	}
	return 0;
}

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Patrick McHardy36499.18%360.00%


Rasmus Villemoes20.54%120.00%


Jan Engelhardt10.27%120.00%


Total367100.00%5100.00%




EXPORT_SYMBOL_GPL(ct_sip_get_header);

/* Get next header field in a list of comma separated values */



static int ct_sip_next_header(const struct nf_conn *ct, const char *dptr,
			      unsigned int dataoff, unsigned int datalen,
			      enum sip_header_types type,
			      unsigned int *matchoff, unsigned int *matchlen)
{
	const struct sip_header *hdr = &ct_sip_hdrs[type];
	const char *start = dptr, *limit = dptr + datalen;
	int shift = 0;

	dptr += dataoff;

	dptr = ct_sip_header_search(dptr, limit, ",", strlen(","));
	if (!dptr)
		return 0;

	dptr = ct_sip_header_search(dptr, limit, hdr->search, hdr->slen);
	if (!dptr)
		return 0;
	dptr += hdr->slen;

	*matchoff = dptr - start;
	*matchlen = hdr->match_len(ct, dptr, limit, &shift);
	if (!*matchlen)
		return -1;
	*matchoff += shift;
	return 1;
}


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Patrick McHardy171100.00%1100.00%


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/* Walk through headers until a parsable one is found or no header of the
 * given type is left. */



static int ct_sip_walk_headers(const struct nf_conn *ct, const char *dptr,
			       unsigned int dataoff, unsigned int datalen,
			       enum sip_header_types type, int *in_header,
			       unsigned int *matchoff, unsigned int *matchlen)
{
	int ret;

	if (in_header && *in_header) {
		while (1) {
			ret = ct_sip_next_header(ct, dptr, dataoff, datalen,
						 type, matchoff, matchlen);
			if (ret > 0)
				return ret;
			if (ret == 0)
				break;
			dataoff += *matchoff;
		}
		*in_header = 0;
	}

	while (1) {
		ret = ct_sip_get_header(ct, dptr, dataoff, datalen,
					type, matchoff, matchlen);
		if (ret > 0)
			break;
		if (ret == 0)
			return ret;
		dataoff += *matchoff;
	}

	if (in_header)
		*in_header = 1;
	return 1;
}


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Patrick McHardy164100.00%1100.00%


Total164100.00%1100.00%



/* Locate a SIP header, parse the URI and return the offset and length of
 * the address as well as the address and port themselves. A stream of
 * headers can be parsed by handing in a non-NULL datalen and in_header
 * pointer.
 */



int ct_sip_parse_header_uri(const struct nf_conn *ct, const char *dptr,
			    unsigned int *dataoff, unsigned int datalen,
			    enum sip_header_types type, int *in_header,
			    unsigned int *matchoff, unsigned int *matchlen,
			    union nf_inet_addr *addr, __be16 *port)
{
	const char *c, *limit = dptr + datalen;
	unsigned int p;
	int ret;

	ret = ct_sip_walk_headers(ct, dptr, dataoff ? *dataoff : 0, datalen,
				  type, in_header, matchoff, matchlen);
	WARN_ON(ret < 0);
	if (ret == 0)
		return ret;

	if (!sip_parse_addr(ct, dptr + *matchoff, &c, addr, limit, true))
		return -1;
	if (*c == ':') {
		c++;
		p = simple_strtoul(c, (char **)&c, 10);
		if (p < 1024 || p > 65535)
			return -1;
		*port = htons(p);
	} else
		*port = htons(SIP_PORT);

	if (dataoff)
		*dataoff = c - dptr;
	return 1;
}

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EXPORT_SYMBOL_GPL(ct_sip_parse_header_uri);




static int ct_sip_parse_param(const struct nf_conn *ct, const char *dptr,
			      unsigned int dataoff, unsigned int datalen,
			      const char *name,
			      unsigned int *matchoff, unsigned int *matchlen)
{
	const char *limit = dptr + datalen;
	const char *start;
	const char *end;

	limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(","));
	if (!limit)
		limit = dptr + datalen;

	start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name));
	if (!start)
		return 0;
	start += strlen(name);

	end = ct_sip_header_search(start, limit, ";", strlen(";"));
	if (!end)
		end = limit;

	*matchoff = start - dptr;
	*matchlen = end - start;
	return 1;
}


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/* Parse address from header parameter and return address, offset and length */



int ct_sip_parse_address_param(const struct nf_conn *ct, const char *dptr,
			       unsigned int dataoff, unsigned int datalen,
			       const char *name,
			       unsigned int *matchoff, unsigned int *matchlen,
			       union nf_inet_addr *addr, bool delim)
{
	const char *limit =