Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org> Signed-off-by: David S. Miller <davem@davemloft.net>
521 lines
12 KiB
C
521 lines
12 KiB
C
/* SIP extension for IP connection tracking.
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*
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* (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar>
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* based on RR's ip_conntrack_ftp.c and other modules.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/ctype.h>
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#include <linux/skbuff.h>
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#include <linux/in.h>
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#include <linux/ip.h>
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#include <linux/udp.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
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#include <linux/netfilter_ipv4/ip_conntrack_sip.h>
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#if 0
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#define DEBUGP printk
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#else
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#define DEBUGP(format, args...)
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#endif
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
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MODULE_DESCRIPTION("SIP connection tracking helper");
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#define MAX_PORTS 8
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static unsigned short ports[MAX_PORTS];
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static int ports_c;
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module_param_array(ports, ushort, &ports_c, 0400);
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MODULE_PARM_DESC(ports, "port numbers of sip servers");
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static unsigned int sip_timeout = SIP_TIMEOUT;
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module_param(sip_timeout, uint, 0600);
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MODULE_PARM_DESC(sip_timeout, "timeout for the master SIP session");
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unsigned int (*ip_nat_sip_hook)(struct sk_buff **pskb,
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enum ip_conntrack_info ctinfo,
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struct ip_conntrack *ct,
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const char **dptr);
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EXPORT_SYMBOL_GPL(ip_nat_sip_hook);
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unsigned int (*ip_nat_sdp_hook)(struct sk_buff **pskb,
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enum ip_conntrack_info ctinfo,
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struct ip_conntrack_expect *exp,
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const char *dptr);
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EXPORT_SYMBOL_GPL(ip_nat_sdp_hook);
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static int digits_len(const char *dptr, const char *limit, int *shift);
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static int epaddr_len(const char *dptr, const char *limit, int *shift);
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static int skp_digits_len(const char *dptr, const char *limit, int *shift);
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static int skp_epaddr_len(const char *dptr, const char *limit, int *shift);
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struct sip_header_nfo {
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const char *lname;
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const char *sname;
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const char *ln_str;
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size_t lnlen;
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size_t snlen;
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size_t ln_strlen;
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int case_sensitive;
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int (*match_len)(const char *, const char *, int *);
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};
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static struct sip_header_nfo ct_sip_hdrs[] = {
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[POS_REG_REQ_URI] = { /* SIP REGISTER request URI */
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.lname = "sip:",
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.lnlen = sizeof("sip:") - 1,
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.ln_str = ":",
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.ln_strlen = sizeof(":") - 1,
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.match_len = epaddr_len
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},
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[POS_REQ_URI] = { /* SIP request URI */
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.lname = "sip:",
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.lnlen = sizeof("sip:") - 1,
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.ln_str = "@",
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.ln_strlen = sizeof("@") - 1,
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.match_len = epaddr_len
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},
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[POS_FROM] = { /* SIP From header */
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.lname = "From:",
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.lnlen = sizeof("From:") - 1,
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.sname = "\r\nf:",
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.snlen = sizeof("\r\nf:") - 1,
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.ln_str = "sip:",
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.ln_strlen = sizeof("sip:") - 1,
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.match_len = skp_epaddr_len,
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},
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[POS_TO] = { /* SIP To header */
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.lname = "To:",
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.lnlen = sizeof("To:") - 1,
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.sname = "\r\nt:",
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.snlen = sizeof("\r\nt:") - 1,
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.ln_str = "sip:",
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.ln_strlen = sizeof("sip:") - 1,
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.match_len = skp_epaddr_len,
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},
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[POS_VIA] = { /* SIP Via header */
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.lname = "Via:",
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.lnlen = sizeof("Via:") - 1,
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.sname = "\r\nv:",
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.snlen = sizeof("\r\nv:") - 1, /* rfc3261 "\r\n" */
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.ln_str = "UDP ",
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.ln_strlen = sizeof("UDP ") - 1,
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.match_len = epaddr_len,
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},
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[POS_CONTACT] = { /* SIP Contact header */
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.lname = "Contact:",
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.lnlen = sizeof("Contact:") - 1,
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.sname = "\r\nm:",
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.snlen = sizeof("\r\nm:") - 1,
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.ln_str = "sip:",
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.ln_strlen = sizeof("sip:") - 1,
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.match_len = skp_epaddr_len
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},
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[POS_CONTENT] = { /* SIP Content length header */
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.lname = "Content-Length:",
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.lnlen = sizeof("Content-Length:") - 1,
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.sname = "\r\nl:",
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.snlen = sizeof("\r\nl:") - 1,
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.ln_str = ":",
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.ln_strlen = sizeof(":") - 1,
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.match_len = skp_digits_len
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},
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[POS_MEDIA] = { /* SDP media info */
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.case_sensitive = 1,
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.lname = "\nm=",
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.lnlen = sizeof("\nm=") - 1,
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.sname = "\rm=",
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.snlen = sizeof("\rm=") - 1,
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.ln_str = "audio ",
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.ln_strlen = sizeof("audio ") - 1,
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.match_len = digits_len
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},
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[POS_OWNER] = { /* SDP owner address*/
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.case_sensitive = 1,
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.lname = "\no=",
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.lnlen = sizeof("\no=") - 1,
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.sname = "\ro=",
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.snlen = sizeof("\ro=") - 1,
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.ln_str = "IN IP4 ",
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.ln_strlen = sizeof("IN IP4 ") - 1,
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.match_len = epaddr_len
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},
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[POS_CONNECTION] = { /* SDP connection info */
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.case_sensitive = 1,
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.lname = "\nc=",
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.lnlen = sizeof("\nc=") - 1,
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.sname = "\rc=",
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.snlen = sizeof("\rc=") - 1,
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.ln_str = "IN IP4 ",
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.ln_strlen = sizeof("IN IP4 ") - 1,
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.match_len = epaddr_len
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},
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[POS_SDP_HEADER] = { /* SDP version header */
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.case_sensitive = 1,
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.lname = "\nv=",
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.lnlen = sizeof("\nv=") - 1,
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.sname = "\rv=",
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.snlen = sizeof("\rv=") - 1,
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.ln_str = "=",
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.ln_strlen = sizeof("=") - 1,
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.match_len = digits_len
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}
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};
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/* get line lenght until first CR or LF seen. */
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int ct_sip_lnlen(const char *line, const char *limit)
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{
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const char *k = line;
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while ((line <= limit) && (*line == '\r' || *line == '\n'))
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line++;
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while (line <= limit) {
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if (*line == '\r' || *line == '\n')
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break;
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line++;
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}
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return line - k;
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}
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EXPORT_SYMBOL_GPL(ct_sip_lnlen);
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/* Linear string search, case sensitive. */
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const char *ct_sip_search(const char *needle, const char *haystack,
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size_t needle_len, size_t haystack_len,
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int case_sensitive)
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{
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const char *limit = haystack + (haystack_len - needle_len);
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while (haystack <= limit) {
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if (case_sensitive) {
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if (strncmp(haystack, needle, needle_len) == 0)
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return haystack;
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} else {
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if (strnicmp(haystack, needle, needle_len) == 0)
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return haystack;
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}
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haystack++;
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}
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return NULL;
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}
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EXPORT_SYMBOL_GPL(ct_sip_search);
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static int digits_len(const char *dptr, const char *limit, int *shift)
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{
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int len = 0;
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while (dptr <= limit && isdigit(*dptr)) {
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dptr++;
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len++;
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}
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return len;
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}
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/* get digits lenght, skiping blank spaces. */
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static int skp_digits_len(const char *dptr, const char *limit, int *shift)
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{
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for (; dptr <= limit && *dptr == ' '; dptr++)
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(*shift)++;
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return digits_len(dptr, limit, shift);
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}
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/* Simple ipaddr parser.. */
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static int parse_ipaddr(const char *cp, const char **endp,
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__be32 *ipaddr, const char *limit)
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{
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unsigned long int val;
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int i, digit = 0;
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for (i = 0, *ipaddr = 0; cp <= limit && i < 4; i++) {
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digit = 0;
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if (!isdigit(*cp))
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break;
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val = simple_strtoul(cp, (char **)&cp, 10);
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if (val > 0xFF)
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return -1;
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((u_int8_t *)ipaddr)[i] = val;
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digit = 1;
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if (*cp != '.')
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break;
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cp++;
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}
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if (!digit)
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return -1;
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if (endp)
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*endp = cp;
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return 0;
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}
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/* skip ip address. returns it lenght. */
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static int epaddr_len(const char *dptr, const char *limit, int *shift)
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{
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const char *aux = dptr;
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__be32 ip;
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if (parse_ipaddr(dptr, &dptr, &ip, limit) < 0) {
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DEBUGP("ip: %s parse failed.!\n", dptr);
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return 0;
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}
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/* Port number */
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if (*dptr == ':') {
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dptr++;
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dptr += digits_len(dptr, limit, shift);
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}
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return dptr - aux;
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}
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/* get address length, skiping user info. */
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static int skp_epaddr_len(const char *dptr, const char *limit, int *shift)
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{
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int s = *shift;
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/* Search for @, but stop at the end of the line.
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* We are inside a sip: URI, so we don't need to worry about
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* continuation lines. */
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while (dptr <= limit &&
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*dptr != '@' && *dptr != '\r' && *dptr != '\n') {
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(*shift)++;
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dptr++;
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}
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if (dptr <= limit && *dptr == '@') {
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dptr++;
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(*shift)++;
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} else
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*shift = s;
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return epaddr_len(dptr, limit, shift);
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}
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/* Returns 0 if not found, -1 error parsing. */
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int ct_sip_get_info(const char *dptr, size_t dlen,
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unsigned int *matchoff,
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unsigned int *matchlen,
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enum sip_header_pos pos)
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{
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struct sip_header_nfo *hnfo = &ct_sip_hdrs[pos];
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const char *limit, *aux, *k = dptr;
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int shift = 0;
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limit = dptr + (dlen - hnfo->lnlen);
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while (dptr <= limit) {
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if ((strncmp(dptr, hnfo->lname, hnfo->lnlen) != 0) &&
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(hnfo->sname == NULL ||
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strncmp(dptr, hnfo->sname, hnfo->snlen) != 0)) {
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dptr++;
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continue;
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}
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aux = ct_sip_search(hnfo->ln_str, dptr, hnfo->ln_strlen,
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ct_sip_lnlen(dptr, limit),
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hnfo->case_sensitive);
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if (!aux) {
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DEBUGP("'%s' not found in '%s'.\n", hnfo->ln_str,
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hnfo->lname);
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return -1;
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}
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aux += hnfo->ln_strlen;
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*matchlen = hnfo->match_len(aux, limit, &shift);
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if (!*matchlen)
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return -1;
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*matchoff = (aux - k) + shift;
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DEBUGP("%s match succeeded! - len: %u\n", hnfo->lname,
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*matchlen);
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return 1;
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}
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DEBUGP("%s header not found.\n", hnfo->lname);
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return 0;
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}
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EXPORT_SYMBOL_GPL(ct_sip_get_info);
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static int set_expected_rtp(struct sk_buff **pskb,
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struct ip_conntrack *ct,
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enum ip_conntrack_info ctinfo,
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__be32 ipaddr, u_int16_t port,
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const char *dptr)
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{
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struct ip_conntrack_expect *exp;
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enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
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int ret;
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typeof(ip_nat_sdp_hook) ip_nat_sdp;
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exp = ip_conntrack_expect_alloc(ct);
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if (exp == NULL)
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return NF_DROP;
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exp->tuple.src.ip = ct->tuplehash[!dir].tuple.src.ip;
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exp->tuple.src.u.udp.port = 0;
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exp->tuple.dst.ip = ipaddr;
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exp->tuple.dst.u.udp.port = htons(port);
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exp->tuple.dst.protonum = IPPROTO_UDP;
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exp->mask.src.ip = htonl(0xFFFFFFFF);
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exp->mask.src.u.udp.port = 0;
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exp->mask.dst.ip = htonl(0xFFFFFFFF);
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exp->mask.dst.u.udp.port = htons(0xFFFF);
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exp->mask.dst.protonum = 0xFF;
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exp->expectfn = NULL;
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exp->flags = 0;
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ip_nat_sdp = rcu_dereference(ip_nat_sdp_hook);
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if (ip_nat_sdp)
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ret = ip_nat_sdp(pskb, ctinfo, exp, dptr);
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else {
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if (ip_conntrack_expect_related(exp) != 0)
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ret = NF_DROP;
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else
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ret = NF_ACCEPT;
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}
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ip_conntrack_expect_put(exp);
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return ret;
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}
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static int sip_help(struct sk_buff **pskb,
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struct ip_conntrack *ct,
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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 = NF_ACCEPT;
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int matchoff, matchlen;
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__be32 ipaddr;
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u_int16_t port;
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typeof(ip_nat_sip_hook) ip_nat_sip;
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/* No Data ? */
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dataoff = (*pskb)->nh.iph->ihl*4 + sizeof(struct udphdr);
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if (dataoff >= (*pskb)->len) {
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DEBUGP("skb->len = %u\n", (*pskb)->len);
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return NF_ACCEPT;
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}
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ip_ct_refresh(ct, *pskb, sip_timeout * HZ);
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if (!skb_is_nonlinear(*pskb))
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dptr = (*pskb)->data + dataoff;
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else {
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DEBUGP("Copy of skbuff not supported yet.\n");
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goto out;
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}
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ip_nat_sip = rcu_dereference(ip_nat_sip_hook);
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if (ip_nat_sip) {
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if (!ip_nat_sip(pskb, ctinfo, ct, &dptr)) {
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ret = NF_DROP;
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goto out;
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}
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}
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/* After this point NAT, could have mangled skb, so
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we need to recalculate payload lenght. */
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datalen = (*pskb)->len - dataoff;
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if (datalen < (sizeof("SIP/2.0 200") - 1))
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goto out;
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/* RTP info only in some SDP pkts */
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if (memcmp(dptr, "INVITE", sizeof("INVITE") - 1) != 0 &&
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memcmp(dptr, "SIP/2.0 200", sizeof("SIP/2.0 200") - 1) != 0) {
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goto out;
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}
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/* Get ip and port address from SDP packet. */
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if (ct_sip_get_info(dptr, datalen, &matchoff, &matchlen,
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POS_CONNECTION) > 0) {
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/* We'll drop only if there are parse problems. */
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if (parse_ipaddr(dptr + matchoff, NULL, &ipaddr,
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dptr + datalen) < 0) {
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ret = NF_DROP;
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goto out;
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}
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if (ct_sip_get_info(dptr, datalen, &matchoff, &matchlen,
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POS_MEDIA) > 0) {
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port = simple_strtoul(dptr + matchoff, NULL, 10);
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if (port < 1024) {
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ret = NF_DROP;
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goto out;
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}
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ret = set_expected_rtp(pskb, ct, ctinfo,
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ipaddr, port, dptr);
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}
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}
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out:
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return ret;
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}
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static struct ip_conntrack_helper sip[MAX_PORTS];
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static char sip_names[MAX_PORTS][10];
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static void fini(void)
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{
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int i;
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for (i = 0; i < ports_c; i++) {
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DEBUGP("unregistering helper for port %d\n", ports[i]);
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ip_conntrack_helper_unregister(&sip[i]);
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}
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}
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static int __init init(void)
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{
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int i, ret;
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char *tmpname;
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if (ports_c == 0)
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ports[ports_c++] = SIP_PORT;
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for (i = 0; i < ports_c; i++) {
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/* Create helper structure */
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memset(&sip[i], 0, sizeof(struct ip_conntrack_helper));
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sip[i].tuple.dst.protonum = IPPROTO_UDP;
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sip[i].tuple.src.u.udp.port = htons(ports[i]);
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sip[i].mask.src.u.udp.port = htons(0xFFFF);
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sip[i].mask.dst.protonum = 0xFF;
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sip[i].max_expected = 2;
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sip[i].timeout = 3 * 60; /* 3 minutes */
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sip[i].me = THIS_MODULE;
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sip[i].help = sip_help;
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tmpname = &sip_names[i][0];
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if (ports[i] == SIP_PORT)
|
|
sprintf(tmpname, "sip");
|
|
else
|
|
sprintf(tmpname, "sip-%d", i);
|
|
sip[i].name = tmpname;
|
|
|
|
DEBUGP("port #%d: %d\n", i, ports[i]);
|
|
|
|
ret = ip_conntrack_helper_register(&sip[i]);
|
|
if (ret) {
|
|
printk("ERROR registering helper for port %d\n",
|
|
ports[i]);
|
|
fini();
|
|
return ret;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
module_init(init);
|
|
module_exit(fini);
|