static int map_addr(struct sk_buff *skb, unsigned int protoff,
unsigned int dataoff,
const char **dptr, unsigned int *datalen,
unsigned int matchoff, unsigned int matchlen,
union nf_inet_addr *addr, __be16 port)
{
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")];
unsigned int buflen;
union nf_inet_addr newaddr;
__be16 newport;
if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, addr) &&
ct->tuplehash[dir].tuple.src.u.udp.port == port) {
newaddr = ct->tuplehash[!dir].tuple.dst.u3;
newport = ct->tuplehash[!dir].tuple.dst.u.udp.port;
} else if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, addr) &&
ct->tuplehash[dir].tuple.dst.u.udp.port == port) {
newaddr = ct->tuplehash[!dir].tuple.src.u3;
newport = ct_sip_info->forced_dport ? :
ct->tuplehash[!dir].tuple.src.u.udp.port;
} else
static int map_addr(struct sk_buff *skb, unsigned int protoff,
unsigned int dataoff,
const char **dptr, unsigned int *datalen,
unsigned int matchoff, unsigned int matchlen,
union nf_inet_addr *addr, __be16 port)
{
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")];
unsigned int buflen;
union nf_inet_addr newaddr;
__be16 newport;
if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, addr) &&
ct->tuplehash[dir].tuple.src.u.udp.port == port) {
newaddr = ct->tuplehash[!dir].tuple.dst.u3;
newport = ct->tuplehash[!dir].tuple.dst.u.udp.port;
} else if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, addr) &&
ct->tuplehash[dir].tuple.dst.u.udp.port == port) {
newaddr = ct->tuplehash[!dir].tuple.src.u3;
newport = ct->tuplehash[!dir].tuple.src.u.udp.port;
} else
return 1;
if (nf_inet_addr_cmp(&newaddr, addr) && newport == port)
return 1;
buflen = sip_sprintf_addr_port(ct, buffer, &newaddr, ntohs(newport));
return mangle_packet(skb, protoff, dataoff, dptr, datalen,
matchoff, matchlen, buffer, buflen);
}
static unsigned int
nf_nat_ipv6_out(unsigned int hooknum,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
#ifdef CONFIG_XFRM
const struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
#endif
unsigned int ret;
/* root is playing with raw sockets. */
if (skb->len < sizeof(struct ipv6hdr))
return NF_ACCEPT;
ret = nf_nat_ipv6_fn(hooknum, skb, in, out, okfn);
#ifdef CONFIG_XFRM
if (ret != NF_DROP && ret != NF_STOLEN &&
!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
(ct = nf_ct_get(skb, &ctinfo)) != NULL) {
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3,
&ct->tuplehash[!dir].tuple.dst.u3) ||
(ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMPV6 &&
ct->tuplehash[dir].tuple.src.u.all !=
ct->tuplehash[!dir].tuple.dst.u.all))
if (nf_xfrm_me_harder(skb, AF_INET6) < 0)
ret = NF_DROP;
}
#endif
return ret;
}
static inline int
same_src(const struct nf_conn *ct,
const struct nf_conntrack_tuple *tuple)
{
const struct nf_conntrack_tuple *t;
t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
return (t->dst.protonum == tuple->dst.protonum &&
nf_inet_addr_cmp(&t->src.u3, &tuple->src.u3) &&
t->src.u.all == tuple->src.u.all);
}
unsigned int
nf_nat_ipv6_local_fn(const struct nf_hook_ops *ops, struct sk_buff *skb,
const struct net_device *in, const struct net_device *out,
unsigned int (*do_chain)(const struct nf_hook_ops *ops,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
struct nf_conn *ct))
{
const struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
unsigned int ret;
int err;
/* root is playing with raw sockets. */
if (skb->len < sizeof(struct ipv6hdr))
return NF_ACCEPT;
ret = nf_nat_ipv6_fn(ops, skb, in, out, do_chain);
if (ret != NF_DROP && ret != NF_STOLEN &&
(ct = nf_ct_get(skb, &ctinfo)) != NULL) {
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3,
&ct->tuplehash[!dir].tuple.src.u3)) {
err = ip6_route_me_harder(skb);
if (err < 0)
ret = NF_DROP_ERR(err);
}
#ifdef CONFIG_XFRM
else if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMPV6 &&
ct->tuplehash[dir].tuple.dst.u.all !=
ct->tuplehash[!dir].tuple.src.u.all) {
err = nf_xfrm_me_harder(skb, AF_INET6);
if (err < 0)
ret = NF_DROP_ERR(err);
}
#endif
}
return ret;
}
unsigned int
nf_nat_ipv6_out(void *priv, struct sk_buff *skb,
const struct nf_hook_state *state,
unsigned int (*do_chain)(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state,
struct nf_conn *ct))
{
#ifdef CONFIG_XFRM
const struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
int err;
#endif
unsigned int ret;
/* root is playing with raw sockets. */
if (skb->len < sizeof(struct ipv6hdr))
return NF_ACCEPT;
ret = nf_nat_ipv6_fn(priv, skb, state, do_chain);
#ifdef CONFIG_XFRM
if (ret != NF_DROP && ret != NF_STOLEN &&
!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
(ct = nf_ct_get(skb, &ctinfo)) != NULL) {
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3,
&ct->tuplehash[!dir].tuple.dst.u3) ||
(ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMPV6 &&
ct->tuplehash[dir].tuple.src.u.all !=
ct->tuplehash[!dir].tuple.dst.u.all)) {
err = nf_xfrm_me_harder(state->net, skb, AF_INET6);
if (err < 0)
ret = NF_DROP_ERR(err);
}
}
#endif
return ret;
}
/* Handles expected signalling connections and media streams */
static void nf_nat_sip_expected(struct nf_conn *ct,
struct nf_conntrack_expect *exp)
{
struct nf_nat_range range;
/* This must be a fresh one. */
BUG_ON(ct->status & IPS_NAT_DONE_MASK);
/* For DST manip, map port here to where it's expected. */
range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED);
range.min_proto = range.max_proto = exp->saved_proto;
range.min_addr = range.max_addr = exp->saved_addr;
nf_nat_setup_info(ct, &range, NF_NAT_MANIP_DST);
/* Change src to where master sends to, but only if the connection
* actually came from the same source. */
if (nf_inet_addr_cmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3,
&ct->master->tuplehash[exp->dir].tuple.src.u3)) {
range.flags = NF_NAT_RANGE_MAP_IPS;
range.min_addr = range.max_addr
= ct->master->tuplehash[!exp->dir].tuple.dst.u3;
nf_nat_setup_info(ct, &range, NF_NAT_MANIP_SRC);
}
}
/* For [FUTURE] fragmentation handling, we want the least-used
* src-ip/dst-ip/proto triple. Fairness doesn't come into it. Thus
* if the range specifies 1.2.3.4 ports 10000-10005 and 1.2.3.5 ports
* 1-65535, we don't do pro-rata allocation based on ports; we choose
* the ip with the lowest src-ip/dst-ip/proto usage.
*/
static void
find_best_ips_proto(const struct nf_conntrack_zone *zone,
struct nf_conntrack_tuple *tuple,
const struct nf_nat_range *range,
const struct nf_conn *ct,
enum nf_nat_manip_type maniptype)
{
union nf_inet_addr *var_ipp;
unsigned int i, max;
/* Host order */
u32 minip, maxip, j, dist;
bool full_range;
/* No IP mapping? Do nothing. */
if (!(range->flags & NF_NAT_RANGE_MAP_IPS))
return;
if (maniptype == NF_NAT_MANIP_SRC)
var_ipp = &tuple->src.u3;
else
var_ipp = &tuple->dst.u3;
/* Fast path: only one choice. */
if (nf_inet_addr_cmp(&range->min_addr, &range->max_addr)) {
*var_ipp = range->min_addr;
return;
}
if (nf_ct_l3num(ct) == NFPROTO_IPV4)
max = sizeof(var_ipp->ip) / sizeof(u32) - 1;
else
max = sizeof(var_ipp->ip6) / sizeof(u32) - 1;
/* Hashing source and destination IPs gives a fairly even
* spread in practice (if there are a small number of IPs
* involved, there usually aren't that many connections
* anyway). The consistency means that servers see the same
* client coming from the same IP (some Internet Banking sites
* like this), even across reboots.
*/
j = jhash2((u32 *)&tuple->src.u3, sizeof(tuple->src.u3) / sizeof(u32),
range->flags & NF_NAT_RANGE_PERSISTENT ?
0 : (__force u32)tuple->dst.u3.all[max] ^ zone->id);
full_range = false;
for (i = 0; i <= max; i++) {
/* If first bytes of the address are at the maximum, use the
* distance. Otherwise use the full range.
*/
if (!full_range) {
minip = ntohl((__force __be32)range->min_addr.all[i]);
maxip = ntohl((__force __be32)range->max_addr.all[i]);
dist = maxip - minip + 1;
} else {
minip = 0;
dist = ~0;
}
var_ipp->all[i] = (__force __u32)
htonl(minip + reciprocal_scale(j, dist));
if (var_ipp->all[i] != range->max_addr.all[i])
full_range = true;
if (!(range->flags & NF_NAT_RANGE_PERSISTENT))
j ^= (__force u32)tuple->dst.u3.all[i];
}
}
/* So, this packet has hit the connection tracking matching code.
Mangle it, and change the expectation to match the new version. */
static unsigned int nf_nat_sdp_media(struct sk_buff *skb, unsigned int protoff,
unsigned int dataoff,
const char **dptr, unsigned int *datalen,
struct nf_conntrack_expect *rtp_exp,
struct nf_conntrack_expect *rtcp_exp,
unsigned int mediaoff,
unsigned int medialen,
union nf_inet_addr *rtp_addr)
{
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
u_int16_t port;
/* Connection will come from reply */
if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3,
&ct->tuplehash[!dir].tuple.dst.u3))
*rtp_addr = rtp_exp->tuple.dst.u3;
else
*rtp_addr = ct->tuplehash[!dir].tuple.dst.u3;
rtp_exp->saved_addr = rtp_exp->tuple.dst.u3;
rtp_exp->tuple.dst.u3 = *rtp_addr;
rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port;
rtp_exp->dir = !dir;
rtp_exp->expectfn = nf_nat_sip_expected;
rtcp_exp->saved_addr = rtcp_exp->tuple.dst.u3;
rtcp_exp->tuple.dst.u3 = *rtp_addr;
rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port;
rtcp_exp->dir = !dir;
rtcp_exp->expectfn = nf_nat_sip_expected;
/* Try to get same pair of ports: if not, try to change them. */
for (port = ntohs(rtp_exp->tuple.dst.u.udp.port);
port != 0; port += 2) {
int ret;
rtp_exp->tuple.dst.u.udp.port = htons(port);
ret = nf_ct_expect_related(rtp_exp);
if (ret == -EBUSY)
continue;
else if (ret < 0) {
port = 0;
break;
}
rtcp_exp->tuple.dst.u.udp.port = htons(port + 1);
ret = nf_ct_expect_related(rtcp_exp);
if (ret == 0)
break;
else if (ret == -EBUSY) {
nf_ct_unexpect_related(rtp_exp);
continue;
} else if (ret < 0) {
nf_ct_unexpect_related(rtp_exp);
port = 0;
break;
}
}
if (port == 0)
goto err1;
/* Update media port. */
if (rtp_exp->tuple.dst.u.udp.port != rtp_exp->saved_proto.udp.port &&
!nf_nat_sdp_port(skb, protoff, dataoff, dptr, datalen,
mediaoff, medialen, port))
goto err2;
return NF_ACCEPT;
err2:
nf_ct_unexpect_related(rtp_exp);
nf_ct_unexpect_related(rtcp_exp);
err1:
return NF_DROP;
}
static unsigned int nf_nat_sip_expect(struct sk_buff *skb, unsigned int protoff,
unsigned int dataoff,
const char **dptr, unsigned int *datalen,
struct nf_conntrack_expect *exp,
unsigned int matchoff,
unsigned int matchlen)
{
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
union nf_inet_addr newaddr;
u_int16_t port;
char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")];
unsigned int buflen;
/* Connection will come from reply */
if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3,
&ct->tuplehash[!dir].tuple.dst.u3))
newaddr = exp->tuple.dst.u3;
else
newaddr = ct->tuplehash[!dir].tuple.dst.u3;
/* If the signalling port matches the connection's source port in the
* original direction, try to use the destination port in the opposite
* direction. */
if (exp->tuple.dst.u.udp.port ==
ct->tuplehash[dir].tuple.src.u.udp.port)
port = ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port);
else
port = ntohs(exp->tuple.dst.u.udp.port);
exp->saved_addr = exp->tuple.dst.u3;
exp->tuple.dst.u3 = newaddr;
exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port;
exp->dir = !dir;
exp->expectfn = nf_nat_sip_expected;
for (; port != 0; port++) {
int ret;
exp->tuple.dst.u.udp.port = htons(port);
ret = nf_ct_expect_related(exp);
if (ret == 0)
break;
else if (ret != -EBUSY) {
port = 0;
break;
}
}
if (port == 0)
return NF_DROP;
if (!nf_inet_addr_cmp(&exp->tuple.dst.u3, &exp->saved_addr) ||
exp->tuple.dst.u.udp.port != exp->saved_proto.udp.port) {
buflen = sip_sprintf_addr_port(ct, buffer, &newaddr, port);
if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
matchoff, matchlen, buffer, buflen))
goto err;
}
return NF_ACCEPT;
err:
nf_ct_unexpect_related(exp);
return NF_DROP;
}
static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff,
unsigned int dataoff,
const char **dptr, unsigned int *datalen)
{
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
unsigned int coff, matchoff, matchlen;
enum sip_header_types hdr;
union nf_inet_addr addr;
__be16 port;
int request, in_header;
/* Basic rules: requests and responses. */
if (strnicmp(*dptr, "SIP/2.0", strlen("SIP/2.0")) != 0) {
if (ct_sip_parse_request(ct, *dptr, *datalen,
&matchoff, &matchlen,
&addr, &port) > 0 &&
!map_addr(skb, protoff, dataoff, dptr, datalen,
matchoff, matchlen, &addr, port))
return NF_DROP;
request = 1;
} else
request = 0;
if (nf_ct_protonum(ct) == IPPROTO_TCP)
hdr = SIP_HDR_VIA_TCP;
else
hdr = SIP_HDR_VIA_UDP;
/* Translate topmost Via header and parameters */
if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
hdr, NULL, &matchoff, &matchlen,
&addr, &port) > 0) {
unsigned int olen, matchend, poff, plen, buflen, n;
char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")];
/* We're only interested in headers related to this
* connection */
if (request) {
if (!nf_inet_addr_cmp(&addr,
&ct->tuplehash[dir].tuple.src.u3) ||
port != ct->tuplehash[dir].tuple.src.u.udp.port)
goto next;
} else {
if (!nf_inet_addr_cmp(&addr,
&ct->tuplehash[dir].tuple.dst.u3) ||
port != ct->tuplehash[dir].tuple.dst.u.udp.port)
goto next;
}
olen = *datalen;
if (!map_addr(skb, protoff, dataoff, dptr, datalen,
matchoff, matchlen, &addr, port))
return NF_DROP;
matchend = matchoff + matchlen + *datalen - olen;
/* The maddr= parameter (RFC 2361) specifies where to send
* the reply. */
if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen,
"maddr=", &poff, &plen,
&addr, true) > 0 &&
nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.src.u3) &&
!nf_inet_addr_cmp(&addr, &ct->tuplehash[!dir].tuple.dst.u3)) {
buflen = sip_sprintf_addr(ct, buffer,
&ct->tuplehash[!dir].tuple.dst.u3,
true);
if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
poff, plen, buffer, buflen))
return NF_DROP;
}
/* The received= parameter (RFC 2361) contains the address
* from which the server received the request. */
if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen,
"received=", &poff, &plen,
&addr, false) > 0 &&
nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.dst.u3) &&
!nf_inet_addr_cmp(&addr, &ct->tuplehash[!dir].tuple.src.u3)) {
buflen = sip_sprintf_addr(ct, buffer,
&ct->tuplehash[!dir].tuple.src.u3,
false);
if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
poff, plen, buffer, buflen))
return NF_DROP;
}
/* The rport= parameter (RFC 3581) contains the port number
* from which the server received the request. */
if (ct_sip_parse_numerical_param(ct, *dptr, matchend, *datalen,
"rport=", &poff, &plen,
&n) > 0 &&
htons(n) == ct->tuplehash[dir].tuple.dst.u.udp.port &&
htons(n) != ct->tuplehash[!dir].tuple.src.u.udp.port) {
__be16 p = ct->tuplehash[!dir].tuple.src.u.udp.port;
buflen = sprintf(buffer, "%u", ntohs(p));
if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
poff, plen, buffer, buflen))
return NF_DROP;
}
}
next:
/* Translate Contact headers */
coff = 0;
in_header = 0;
while (ct_sip_parse_header_uri(ct, *dptr, &coff, *datalen,
SIP_HDR_CONTACT, &in_header,
&matchoff, &matchlen,
&addr, &port) > 0) {
if (!map_addr(skb, protoff, dataoff, dptr, datalen,
matchoff, matchlen,
&addr, port))
return NF_DROP;
}
if (!map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_FROM) ||
!map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_TO))
return NF_DROP;
return NF_ACCEPT;
}
/*
* Mangle the "Transport:" header:
* - Replace all occurences of "client_port=<spec>"
* - Handle destination parameter
*
* In:
* ct, ctinfo = conntrack context
* skb = packet
* tranoff = Transport header offset from TCP data
* tranlen = Transport header length (incl. CRLF)
* rport_lo = replacement low port (host endian)
* rport_hi = replacement high port (host endian)
*
* Returns packet size difference.
*
* Assumes that a complete transport header is present, ending with CR or LF
*/
static int
rtsp_mangle_tran(enum ip_conntrack_info ctinfo,
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,7,0)
unsigned int protoff,
#endif
struct nf_conntrack_expect* rtp_exp,
struct nf_conntrack_expect* rtcp_exp,
struct ip_ct_rtsp_expect* prtspexp,
struct sk_buff* skb, uint tranoff, uint tranlen)
{
char* ptcp;
uint tcplen;
char* ptran;
char rbuf1[16]; /* Replacement buffer (one port) */
uint rbuf1len; /* Replacement len (one port) */
char rbufa[16]; /* Replacement buffer (all ports) */
uint rbufalen; /* Replacement len (all ports) */
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,7,0)
union nf_inet_addr newip;
#else
u_int32_t newip;
#endif
u_int16_t loport, hiport;
uint off = 0;
uint diff; /* Number of bytes we removed */
struct nf_conn *ct = rtp_exp->master;
/* struct nf_conn *ct = nf_ct_get(skb, &ctinfo); */
struct nf_conntrack_tuple *rtp_t;
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,7,0)
char szextaddr[INET6_ADDRSTRLEN];
#else
char szextaddr[INET_ADDRSTRLEN];
#endif
uint extaddrlen;
int is_stun;
get_skb_tcpdata(skb, &ptcp, &tcplen);
ptran = ptcp+tranoff;
if (tranoff+tranlen > tcplen || tcplen-tranoff < tranlen ||
tranlen < 10 || !iseol(ptran[tranlen-1]) ||
nf_strncasecmp(ptran, "Transport:", 10) != 0) {
pr_info("sanity check failed\n");
return 0;
}
off += 10;
SKIP_WSPACE(ptcp+tranoff, tranlen, off);
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,7,0)
newip = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3;
rtp_t = &rtp_exp->tuple;
rtp_t->dst.u3 = newip;
if (rtcp_exp) {
rtcp_exp->tuple.dst.u3 = newip;
}
extaddrlen = rtsp_sprintf_addr(ct, szextaddr, &newip, true); // FIXME handle extip
pr_debug("stunaddr=%s (auto)\n", szextaddr);
#else
newip = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip;
rtp_t = &rtp_exp->tuple;
rtp_t->dst.u3.ip = newip;
if (rtcp_exp) {
rtcp_exp->tuple.dst.u3.ip = newip;
}
extaddrlen = extip ? sprintf(szextaddr, "%pI4", &extip)
: sprintf(szextaddr, "%pI4", &newip);
pr_debug("stunaddr=%s (%s)\n", szextaddr, (extip?"forced":"auto"));
#endif
hiport = 0;
rbuf1len = rbufalen = 0;
switch (prtspexp->pbtype) {
case pb_single:
for (loport = prtspexp->loport; loport != 0; loport++) { /* XXX: improper wrap? */
rtp_t->dst.u.udp.port = htons(loport);
if (nf_ct_expect_related(rtp_exp) == 0) {
pr_debug("using port %hu\n", loport);
break;
}
}
if (loport != 0) {
rbuf1len = sprintf(rbuf1, "%hu", loport);
rbufalen = sprintf(rbufa, "%hu", loport);
}
break;
case pb_range:
for (loport = prtspexp->loport; loport != 0; loport += 2) { /* XXX: improper wrap? */
rtp_t->dst.u.udp.port = htons(loport);
if (nf_ct_expect_related(rtp_exp) != 0) {
continue;
}
hiport = loport + 1;
rtcp_exp->tuple.dst.u.udp.port = htons(hiport);
if (nf_ct_expect_related(rtcp_exp) != 0) {
nf_ct_unexpect_related(rtp_exp);
continue;
}
/* FIXME: invalid print in case of ipv6 */
pr_debug("nat expect_related %pI4:%u-%u-%pI4:%u-%u\n",
&rtp_exp->tuple.src.u3.ip,
ntohs(rtp_exp->tuple.src.u.udp.port),
ntohs(rtcp_exp->tuple.src.u.udp.port),
&rtp_exp->tuple.dst.u3.ip,
ntohs(rtp_exp->tuple.dst.u.udp.port),
ntohs(rtcp_exp->tuple.dst.u.udp.port));
break;
}
if (loport != 0) {
rbuf1len = sprintf(rbuf1, "%hu", loport);
rbufalen = sprintf(rbufa, "%hu-%hu", loport, hiport);
}
break;
case pb_discon:
for (loport = prtspexp->loport; loport != 0; loport++) { /* XXX: improper wrap? */
rtp_t->dst.u.udp.port = htons(loport);
if (nf_ct_expect_related(rtp_exp) == 0) {
pr_debug("using port %hu (1 of 2)\n", loport);
break;
}
}
for (hiport = prtspexp->hiport; hiport != 0; hiport++) { /* XXX: improper wrap? */
rtp_t->dst.u.udp.port = htons(hiport);
if (nf_ct_expect_related(rtp_exp) == 0) {
pr_debug("using port %hu (2 of 2)\n", hiport);
break;
}
}
if (loport != 0 && hiport != 0) {
rbuf1len = sprintf(rbuf1, "%hu", loport);
rbufalen = sprintf(rbufa, hiport == loport+1 ?
"%hu-%hu":"%hu/%hu", loport, hiport);
}
break;
}
if (rbuf1len == 0)
return 0; /* cannot get replacement port(s) */
/* Transport: tran;field;field=val,tran;field;field=val,...
`off` is set to the start of Transport value from start of line
*/
while (off < tranlen) {
uint saveoff;
const char* pparamend;
uint nextparamoff;
pparamend = memchr(ptran+off, ',', tranlen-off);
pparamend = (pparamend == NULL) ? ptran+tranlen : pparamend+1;
nextparamoff = pparamend-ptran;
/*
* We pass over each param twice. On the first pass, we look for a
* destination= field. It is handled by the security policy. If it
* is present, allowed, and equal to our external address, we assume
* that STUN is being used and we leave the client_port= field alone.
*/
is_stun = 0;
saveoff = off;
while (off < nextparamoff) {
const char* pfieldend;
uint nextfieldoff;
pfieldend = memchr(ptran+off, ';', nextparamoff-off);
nextfieldoff = (pfieldend == NULL) ? nextparamoff : pfieldend-ptran+1;
if (dstact != DSTACT_NONE && strncmp(ptran+off, "destination=", 12) == 0) {
if (strncmp(ptran+off+12, szextaddr, extaddrlen) == 0)
is_stun = 1;
if (dstact == DSTACT_STRIP || (dstact == DSTACT_AUTO && !is_stun)) {
uint dstoff = (ptran-ptcp)+off;
uint dstlen = nextfieldoff-off;
char* pdstrep = NULL;
uint dstreplen = 0;
diff = dstlen;
if (dstact == DSTACT_AUTO && !is_stun) {
pr_debug("RTSP: replace dst addr\n");
dstoff += 12;
dstlen -= 13;
pdstrep = szextaddr;
dstreplen = extaddrlen;
diff = nextfieldoff-off-13-extaddrlen;
}
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,7,0)
if (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo, protoff,
dstoff, dstlen, pdstrep, dstreplen)) {
#else
if (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo,
dstoff, dstlen, pdstrep, dstreplen)) {
#endif
/* mangle failed, all we can do is bail */
nf_ct_unexpect_related(rtp_exp);
if (rtcp_exp)
nf_ct_unexpect_related(rtcp_exp);
return 0;
}
get_skb_tcpdata(skb, &ptcp, &tcplen);
ptran = ptcp+tranoff;
tranlen -= diff;
nextparamoff -= diff;
nextfieldoff -= diff;
}
}
off = nextfieldoff;
}
if (is_stun)
continue;
off = saveoff;
while (off < nextparamoff) {
const char* pfieldend;
uint nextfieldoff;
pfieldend = memchr(ptran+off, ';', nextparamoff-off);
nextfieldoff = (pfieldend == NULL) ? nextparamoff : pfieldend-ptran+1;
if (strncmp(ptran+off, "client_port=", 12) == 0) {
u_int16_t port;
uint numlen;
uint origoff;
uint origlen;
char* rbuf = rbuf1;
uint rbuflen = rbuf1len;
off += 12;
origoff = (ptran-ptcp)+off;
origlen = 0;
numlen = nf_strtou16(ptran+off, &port);
off += numlen;
origlen += numlen;
if (port != prtspexp->loport) {
pr_debug("multiple ports found, port %hu ignored\n", port);
} else {
if (ptran[off] == '-' || ptran[off] == '/') {
off++;
origlen++;
numlen = nf_strtou16(ptran+off, &port);
off += numlen;
origlen += numlen;
rbuf = rbufa;
rbuflen = rbufalen;
}
/*
* note we cannot just memcpy() if the sizes are the same.
* the mangle function does skb resizing, checks for a
* cloned skb, and updates the checksums.
*
* parameter 4 below is offset from start of tcp data.
*/
diff = origlen-rbuflen;
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,7,0)
if (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo, protoff,
origoff, origlen, rbuf, rbuflen)) {
#else
if (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo,
origoff, origlen, rbuf, rbuflen)) {
#endif
/* mangle failed, all we can do is bail */
nf_ct_unexpect_related(rtp_exp);
if (rtcp_exp)
nf_ct_unexpect_related(rtcp_exp);
return 0;
}
get_skb_tcpdata(skb, &ptcp, &tcplen);
ptran = ptcp+tranoff;
tranlen -= diff;
nextparamoff -= diff;
nextfieldoff -= diff;
}
}
off = nextfieldoff;
}
off = nextparamoff;
}
return 1;
}
static uint
help_out(struct sk_buff *skb, enum ip_conntrack_info ctinfo,
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,7,0)
unsigned int protoff,
#endif
unsigned int matchoff, unsigned int matchlen,
struct ip_ct_rtsp_expect* prtspexp,
struct nf_conntrack_expect* rtp_exp,
struct nf_conntrack_expect* rtcp_exp)
{
char* ptcp;
uint tcplen;
uint hdrsoff;
uint hdrslen;
uint lineoff;
uint linelen;
uint off;
int dir = CTINFO2DIR(ctinfo);
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,7,0)
union nf_inet_addr saddr = rtp_exp->master->tuplehash[dir].tuple.src.u3;
#else
__be32 saddr = rtp_exp->master->tuplehash[dir].tuple.src.u3.ip;
#endif
//struct iphdr* iph = (struct iphdr*)(*pskb)->nh.iph;
//struct tcphdr* tcph = (struct tcphdr*)((void*)iph + iph->ihl*4);
get_skb_tcpdata(skb, &ptcp, &tcplen);
hdrsoff = matchoff;//exp->seq - ntohl(tcph->seq);
hdrslen = matchlen;
off = hdrsoff;
pr_debug("NAT rtsp help_out\n");
while (nf_mime_nextline(ptcp, hdrsoff+hdrslen, &off, &lineoff, &linelen)) {
if (linelen == 0)
break;
if (off > hdrsoff+hdrslen) {
pr_info("!! overrun !!");
break;
}
pr_debug("hdr: len=%u, %.*s", linelen, (int)linelen, ptcp+lineoff);
if (nf_strncasecmp(ptcp+lineoff, "Transport:", 10) == 0) {
uint oldtcplen = tcplen;
pr_debug("hdr: Transport\n");
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,7,0)
if (!rtsp_mangle_tran(ctinfo, protoff, rtp_exp, rtcp_exp,
prtspexp, skb, lineoff, linelen)) {
#else
if (!rtsp_mangle_tran(ctinfo, rtp_exp, rtcp_exp, prtspexp,
skb, lineoff, linelen)) {
#endif
pr_debug("hdr: Transport mangle failed");
break;
}
rtp_exp->expectfn = nf_nat_rtsp_expected;
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,7,0)
rtp_exp->saved_addr = saddr;
#else
rtp_exp->saved_ip = saddr;
#endif
rtp_exp->saved_proto.udp.port = htons(prtspexp->loport);
rtp_exp->dir = !dir;
if (rtcp_exp) {
rtcp_exp->expectfn = nf_nat_rtsp_expected;
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,7,0)
rtcp_exp->saved_addr = saddr;
#else
rtcp_exp->saved_ip = saddr;
#endif
rtcp_exp->saved_proto.udp.port = htons(prtspexp->hiport);
rtcp_exp->dir = !dir;
}
get_skb_tcpdata(skb, &ptcp, &tcplen);
hdrslen -= (oldtcplen-tcplen);
off -= (oldtcplen-tcplen);
lineoff -= (oldtcplen-tcplen);
linelen -= (oldtcplen-tcplen);
pr_debug("rep: len=%u, %.*s", linelen, (int)linelen, ptcp+lineoff);
}
}
return NF_ACCEPT;
}
static unsigned int
nf_nat_rtsp(struct sk_buff *skb, enum ip_conntrack_info ctinfo,
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,7,0)
unsigned int protoff,
#endif
unsigned int matchoff, unsigned int matchlen,
struct ip_ct_rtsp_expect* prtspexp,
struct nf_conntrack_expect* rtp_exp,
struct nf_conntrack_expect* rtcp_exp)
{
int dir = CTINFO2DIR(ctinfo);
int rc = NF_ACCEPT;
switch (dir) {
case IP_CT_DIR_ORIGINAL:
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,7,0)
rc = help_out(skb, ctinfo, protoff, matchoff, matchlen, prtspexp,
rtp_exp, rtcp_exp);
#else
rc = help_out(skb, ctinfo, matchoff, matchlen, prtspexp,
rtp_exp, rtcp_exp);
#endif
break;
case IP_CT_DIR_REPLY:
pr_debug("unmangle ! %u\n", ctinfo);
/* XXX: unmangle */
rc = NF_ACCEPT;
break;
}
//UNLOCK_BH(&ip_rtsp_lock);
return rc;
}
static void nf_nat_rtsp_expected(struct nf_conn* ct, struct nf_conntrack_expect *exp)
{
#if LINUX_VERSION_CODE < KERNEL_VERSION(3,3,0) || LINUX_VERSION_CODE >= KERNEL_VERSION(3,7,0)
struct nf_nat_range range;
#else
struct nf_nat_ipv4_range range;
#endif
/* This must be a fresh one. */
BUG_ON(ct->status & IPS_NAT_DONE_MASK);
/* For DST manip, map port here to where it's expected. */
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,7,0)
range.min_proto = range.max_proto = exp->saved_proto;
range.min_addr = range.max_addr = exp->saved_addr;
#else
range.min = range.max = exp->saved_proto;
range.min_ip = range.max_ip = exp->saved_ip;
#endif
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,3,0)
range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED);
nf_nat_setup_info(ct, &range, NF_NAT_MANIP_DST);
#else
range.flags = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED);
nf_nat_setup_info(ct, &range, IP_NAT_MANIP_DST);
#endif
/* Change src to where master sends to, but only if the connection
* actually came from the same source. */
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,7,0)
if (nf_inet_addr_cmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3,
&ct->master->tuplehash[exp->dir].tuple.src.u3)) {
range.min_addr = range.max_addr
= ct->master->tuplehash[!exp->dir].tuple.dst.u3;
#else
if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip ==
ct->master->tuplehash[exp->dir].tuple.src.u3.ip) {
range.min_ip = range.max_ip
= ct->master->tuplehash[!exp->dir].tuple.dst.u3.ip;
#endif
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,3,0)
range.flags = NF_NAT_RANGE_MAP_IPS;
nf_nat_setup_info(ct, &range, NF_NAT_MANIP_SRC);
#else
range.flags = IP_NAT_RANGE_MAP_IPS;
nf_nat_setup_info(ct, &range, IP_NAT_MANIP_SRC);
#endif
}
}
static void __exit fini(void)
{
rcu_assign_pointer(nf_nat_rtsp_hook, NULL);
synchronize_net();
}
static int __init init(void)
{
printk("nf_nat_rtsp v" IP_NF_RTSP_VERSION " loading\n");
BUG_ON(nf_nat_rtsp_hook);
rcu_assign_pointer(nf_nat_rtsp_hook, nf_nat_rtsp);
if (stunaddr != NULL)
extip = in_aton(stunaddr);
if (destaction != NULL) {
if (strcmp(destaction, "auto") == 0)
dstact = DSTACT_AUTO;
if (strcmp(destaction, "strip") == 0)
dstact = DSTACT_STRIP;
if (strcmp(destaction, "none") == 0)
dstact = DSTACT_NONE;
}
return 0;
}
