github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-09-22 12:44:03 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

netfilter: nf_nat_sip: rewind offset when NAT shrinks the packet

Browse Source 
sashiko says:
 If map_addr() changes the packet length, such as when the public NAT IP
 string is shorter or longer than the internal IP, coff will still point to
 the offset relative to the pre-mangled packet.
 If the packet shrinks, coff could overshoot the correct position,
 potentially causing the next ct_sip_parse_header_uri() call to silently
 skip bytes and miss subsequent Contact headers. Could this lead to a
 failure to NAT those subsequent headers and leak internal network details?

Fixes: c978cd3a93 ("[NETFILTER]: nf_nat_sip: translate all Contact headers")
Assisted-by: Claude:claude-sonnet-4-6
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2026-07-06 14:30:55 +02:00 committed by Pablo Neira Ayuso
parent 4172fd3697
commit 16aecbe303
1 changed files with 5 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
net/netfilter/nf_nat_sip.c
View File

@ -273,12 +273,17 @@ static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff,
SIP_HDR_CONTACT, &in_header,
&matchoff, &matchlen,
&addr, &port) > 0) {
int old_len = skb->len, delta;
if (!map_addr(skb, protoff, dataoff, dptr, datalen,
matchoff, matchlen,
&addr, port)) {
nf_ct_helper_log(skb, ct, "cannot mangle contact");
return NF_DROP;
}
delta = (int)skb->len - old_len;
coff += delta;
}
if (!map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_FROM) ||