diff options
| -rw-r--r-- | include/linux/netfilter/nf_conntrack_sip.h | 49 | ||||
| -rw-r--r-- | net/ipv4/netfilter/nf_nat_sip.c | 69 | ||||
| -rw-r--r-- | net/netfilter/nf_conntrack_sip.c | 159 |
3 files changed, 169 insertions, 108 deletions
diff --git a/include/linux/netfilter/nf_conntrack_sip.h b/include/linux/netfilter/nf_conntrack_sip.h index b94de3d60303..9131cbc9b9de 100644 --- a/include/linux/netfilter/nf_conntrack_sip.h +++ b/include/linux/netfilter/nf_conntrack_sip.h @@ -13,12 +13,42 @@ enum sip_header_pos { POS_VIA, POS_CONTACT, POS_CONTENT, - POS_MEDIA, - POS_OWNER_IP4, - POS_CONNECTION_IP4, - POS_OWNER_IP6, - POS_CONNECTION_IP6, - POS_SDP_HEADER, +}; + +struct sip_header { + const char *name; + const char *cname; + const char *search; + unsigned int len; + unsigned int clen; + unsigned int slen; + int (*match_len)(const struct nf_conn *ct, + const char *dptr, const char *limit, + int *shift); +}; + +#define __SIP_HDR(__name, __cname, __search, __match) \ +{ \ + .name = (__name), \ + .len = sizeof(__name) - 1, \ + .cname = (__cname), \ + .clen = (__cname) ? sizeof(__cname) - 1 : 0, \ + .search = (__search), \ + .slen = (__search) ? sizeof(__search) - 1 : 0, \ + .match_len = (__match), \ +} + +#define SDP_HDR(__name, __search, __match) \ + __SIP_HDR(__name, NULL, __search, __match) + +enum sdp_header_types { + SDP_HDR_UNSPEC, + SDP_HDR_VERSION, + SDP_HDR_OWNER_IP4, + SDP_HDR_CONNECTION_IP4, + SDP_HDR_OWNER_IP6, + SDP_HDR_CONNECTION_IP6, + SDP_HDR_MEDIA, }; extern unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb, @@ -36,5 +66,12 @@ extern int ct_sip_lnlen(const char *line, const char *limit); extern const char *ct_sip_search(const char *needle, const char *haystack, size_t needle_len, size_t haystack_len, int case_sensitive); + +extern int ct_sip_get_sdp_header(const struct nf_conn *ct, const char *dptr, + unsigned int dataoff, unsigned int datalen, + enum sdp_header_types type, + enum sdp_header_types term, + unsigned int *matchoff, unsigned int *matchlen); + #endif /* __KERNEL__ */ #endif /* __NF_CONNTRACK_SIP_H__ */ diff --git a/net/ipv4/netfilter/nf_nat_sip.c b/net/ipv4/netfilter/nf_nat_sip.c index dd1b2d86deee..aa8a4f492baf 100644 --- a/net/ipv4/netfilter/nf_nat_sip.c +++ b/net/ipv4/netfilter/nf_nat_sip.c @@ -147,51 +147,46 @@ static unsigned int ip_nat_sip(struct sk_buff *skb, return NF_ACCEPT; } -static unsigned int mangle_sip_packet(struct sk_buff *skb, - const char **dptr, unsigned int *datalen, - char *buffer, int bufflen, - enum sip_header_pos pos) +static int mangle_content_len(struct sk_buff *skb, + const char **dptr, unsigned int *datalen) { enum ip_conntrack_info ctinfo; struct nf_conn *ct = nf_ct_get(skb, &ctinfo); - unsigned int matchlen, matchoff; + unsigned int matchoff, matchlen; + char buffer[sizeof("65536")]; + int buflen, c_len; + /* Get actual SDP length */ + if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen, + SDP_HDR_VERSION, SDP_HDR_UNSPEC, + &matchoff, &matchlen) <= 0) + return 0; + c_len = *datalen - matchoff + strlen("v="); + + /* Now, update SDP length */ if (ct_sip_get_info(ct, *dptr, *datalen, &matchoff, &matchlen, - pos) <= 0) + POS_CONTENT) <= 0) return 0; + buflen = sprintf(buffer, "%u", c_len); return mangle_packet(skb, dptr, datalen, matchoff, matchlen, - buffer, bufflen); + buffer, buflen); } -static int mangle_content_len(struct sk_buff *skb, - const char **dptr, unsigned int *datalen) +static unsigned mangle_sdp_packet(struct sk_buff *skb, + const char **dptr, unsigned int *datalen, + enum sdp_header_types type, + char *buffer, int buflen) { enum ip_conntrack_info ctinfo; struct nf_conn *ct = nf_ct_get(skb, &ctinfo); - unsigned int matchoff, matchlen; - char buffer[sizeof("65536")]; - int bufflen; + unsigned int matchlen, matchoff; - /* Get actual SDP length */ - if (ct_sip_get_info(ct, *dptr, *datalen, &matchoff, - &matchlen, POS_SDP_HEADER) > 0) { - - /* since ct_sip_get_info() give us a pointer passing 'v=' - we need to add 2 bytes in this count. */ - int c_len = *datalen - matchoff + 2; - - /* Now, update SDP length */ - if (ct_sip_get_info(ct, *dptr, *datalen, &matchoff, - &matchlen, POS_CONTENT) > 0) { - - bufflen = sprintf(buffer, "%u", c_len); - return mangle_packet(skb, dptr, datalen, - matchoff, matchlen, - buffer, bufflen); - } - } - return 0; + if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen, type, SDP_HDR_UNSPEC, + &matchoff, &matchlen) <= 0) + return 0; + return mangle_packet(skb, dptr, datalen, matchoff, matchlen, + buffer, buflen); } static unsigned int mangle_sdp(struct sk_buff *skb, @@ -205,18 +200,18 @@ static unsigned int mangle_sdp(struct sk_buff *skb, /* Mangle owner and contact info. */ bufflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(newip)); - if (!mangle_sip_packet(skb, dptr, datalen, buffer, bufflen, - POS_OWNER_IP4)) + if (!mangle_sdp_packet(skb, dptr, datalen, SDP_HDR_OWNER_IP4, + buffer, bufflen)) return 0; - if (!mangle_sip_packet(skb, dptr, datalen, buffer, bufflen, - POS_CONNECTION_IP4)) + if (!mangle_sdp_packet(skb, dptr, datalen, SDP_HDR_CONNECTION_IP4, + buffer, bufflen)) return 0; /* Mangle media port. */ bufflen = sprintf(buffer, "%u", port); - if (!mangle_sip_packet(skb, dptr, datalen, buffer, bufflen, - POS_MEDIA)) + if (!mangle_sdp_packet(skb, dptr, datalen, SDP_HDR_MEDIA, + buffer, bufflen)) return 0; return mangle_content_len(skb, dptr, datalen); diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c index cf19a7082a75..801fcb3c749f 100644 --- a/net/netfilter/nf_conntrack_sip.c +++ b/net/netfilter/nf_conntrack_sip.c @@ -124,66 +124,6 @@ static const struct sip_header_nfo ct_sip_hdrs[] = { .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. */ @@ -363,6 +303,92 @@ int ct_sip_get_info(const struct nf_conn *ct, } EXPORT_SYMBOL_GPL(ct_sip_get_info); +/* SDP header parsing: a SDP session description contains an ordered set of + * headers, starting with a section containing general session parameters, + * optionally followed by multiple media descriptions. + * + * SDP headers always start at the beginning of a line. According to RFC 2327: + * "The sequence CRLF (0x0d0a) is used to end a record, although parsers should + * be tolerant and also accept records terminated with a single newline + * character". We handle both cases. + */ +static const struct sip_header ct_sdp_hdrs[] = { + [SDP_HDR_VERSION] = SDP_HDR("v=", NULL, digits_len), + [SDP_HDR_OWNER_IP4] = SDP_HDR("o=", "IN IP4 ", epaddr_len), + [SDP_HDR_CONNECTION_IP4] = SDP_HDR("c=", "IN IP4 ", epaddr_len), + [SDP_HDR_OWNER_IP6] = SDP_HDR("o=", "IN IP6 ", epaddr_len), + [SDP_HDR_CONNECTION_IP6] = SDP_HDR("c=", "IN IP6 ", epaddr_len), + [SDP_HDR_MEDIA] = SDP_HDR("m=", "audio ", digits_len), +}; + +/* Linear string search within SDP header values */ +static const char *ct_sdp_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') + break; + if (strncmp(dptr, needle, len) == 0) + return dptr; + } + return NULL; +} + +/* Locate a SDP header (optionally a substring within the header value), + * optionally stopping at the first occurence of the term header, parse + * it and return the offset and length of the data we're interested in. + */ +int ct_sip_get_sdp_header(const struct nf_conn *ct, const char *dptr, + unsigned int dataoff, unsigned int datalen, + enum sdp_header_types type, + enum sdp_header_types term, + unsigned int *matchoff, unsigned int *matchlen) +{ + const struct sip_header *hdr = &ct_sdp_hdrs[type]; + const struct sip_header *thdr = &ct_sdp_hdrs[term]; + 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; + } + + if (term != SDP_HDR_UNSPEC && + limit - dptr >= thdr->len && + strnicmp(dptr, thdr->name, thdr->len) == 0) + break; + else if (limit - dptr >= hdr->len && + strnicmp(dptr, hdr->name, hdr->len) == 0) + dptr += hdr->len; + else + continue; + + *matchoff = dptr - start; + if (hdr->search) { + dptr = ct_sdp_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; +} +EXPORT_SYMBOL_GPL(ct_sip_get_sdp_header); + static int set_expected_rtp(struct sk_buff *skb, const char **dptr, unsigned int *datalen, union nf_inet_addr *addr, __be16 port) @@ -408,7 +434,7 @@ static int sip_help(struct sk_buff *skb, int ret = NF_ACCEPT; unsigned int matchoff, matchlen; u_int16_t port; - enum sip_header_pos pos; + enum sdp_header_types type; typeof(nf_nat_sip_hook) nf_nat_sip; /* No Data ? */ @@ -446,8 +472,10 @@ static int sip_help(struct sk_buff *skb, 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) { + type = family == AF_INET ? SDP_HDR_CONNECTION_IP4 : + SDP_HDR_CONNECTION_IP6; + if (ct_sip_get_sdp_header(ct, dptr, 0, datalen, type, SDP_HDR_UNSPEC, + &matchoff, &matchlen) > 0) { /* We'll drop only if there are parse problems. */ if (!parse_addr(ct, dptr + matchoff, NULL, &addr, @@ -455,8 +483,9 @@ static int sip_help(struct sk_buff *skb, ret = NF_DROP; goto out; } - if (ct_sip_get_info(ct, dptr, datalen, &matchoff, &matchlen, - POS_MEDIA) > 0) { + if (ct_sip_get_sdp_header(ct, dptr, 0, datalen, + SDP_HDR_MEDIA, SDP_HDR_UNSPEC, + &matchoff, &matchlen) > 0) { port = simple_strtoul(dptr + matchoff, NULL, 10); if (port < 1024) { |