[PATCH 3.16 173/306] netfilter: nf_conntrack_sip: extend request line validation

[Ben Hutchings]

3.16.40-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ulrich Weber <ulrich.weber@xxxxxxxxxxxx>

commit 444f901742d054a4cd5ff045871eac5131646cfb upstream.

on SIP requests, so a fragmented TCP SIP packet from an allow header starting with
 INVITE,NOTIFY,OPTIONS,REFER,REGISTER,UPDATE,SUBSCRIBE
 Content-Length: 0

will not bet interpreted as an INVITE request. Also Request-URI must start with an alphabetic character.

Confirm with RFC 3261
 Request-Line   =  Method SP Request-URI SP SIP-Version CRLF

Fixes: 30f33e6dee80 ("[NETFILTER]: nf_conntrack_sip: support method specific request/response handling")
Signed-off-by: Ulrich Weber <ulrich.weber@xxxxxxxxxxxx>
Acked-by: Marco Angaroni <marcoangaroni@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 net/netfilter/nf_conntrack_sip.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/net/netfilter/nf_conntrack_sip.c
+++ b/net/netfilter/nf_conntrack_sip.c
@@ -1434,9 +1434,12 @@ static int process_sip_request(struct sk
 		handler = &sip_handlers[i];
 		if (handler->request == NULL)
 			continue;
-		if (*datalen < handler->len ||
+		if (*datalen < handler->len + 2 ||
 		    strnicmp(*dptr, handler->method, handler->len))
 			continue;
+		if ((*dptr)[handler->len] != ' ' ||
+		    !isalpha((*dptr)[handler->len+1]))
+			continue;
 
 		if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ,
 				      &matchoff, &matchlen) <= 0) {