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

Ben Hutchings
2017-02-15T23:50:42Z

From: Ulrich Weber <ulrich.weber@riverbed.com>

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@riverbed.com>
Acked-by: Marco Angaroni <marcoangaroni@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
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) {