Commit f2ad52c9 authored by Holger Eitzenberger's avatar Holger Eitzenberger Committed by David S. Miller
Browse files

[NETFILTER]: Fix CID offset bug in PPTP NAT helper debug message

The recent (kernel fix for PPTP NAT helper introduced a
bug - which only appears if DEBUGP is enabled though.

The calculation of the CID offset into a PPTP request struct is
not correct, so that at least not the correct CID is displayed
if DEBUGP is enabled.

This patch corrects CID offset calculation and introduces a #define
for that.

Signed-off-by: default avatarHolger Eitzenberger <>
Signed-off-by: default avatarPatrick McHardy <>
Signed-off-by: default avatarDavid S. Miller <>
parent 77ff72d5
......@@ -52,6 +52,8 @@
#define IP_NAT_PPTP_VERSION "3.0"
#define REQ_CID(req, off) (*(u_int16_t *)((char *)(req) + (off)))
MODULE_AUTHOR("Harald Welte <>");
MODULE_DESCRIPTION("Netfilter NAT helper module for PPTP");
......@@ -198,7 +200,7 @@ pptp_outbound_pkt(struct sk_buff **pskb,
* down to here */
DEBUGP("altering call id from 0x%04x to 0x%04x\n",
ntohs(*(u_int16_t *)pptpReq + cid_off), ntohs(new_callid));
ntohs(REQ_CID(pptpReq, cid_off)), ntohs(new_callid));
/* mangle packet */
if (ip_nat_mangle_tcp_packet(pskb, ct, ctinfo,
......@@ -342,7 +344,7 @@ pptp_inbound_pkt(struct sk_buff **pskb,
/* mangle packet */
DEBUGP("altering peer call id from 0x%04x to 0x%04x\n",
ntohs(*(u_int16_t *)pptpReq + pcid_off), ntohs(new_pcid));
ntohs(REQ_CID(pptpReq, pcid_off)), ntohs(new_pcid));
if (ip_nat_mangle_tcp_packet(pskb, ct, ctinfo,
pcid_off + sizeof(struct pptp_pkt_hdr) +
......@@ -353,7 +355,7 @@ pptp_inbound_pkt(struct sk_buff **pskb,
if (new_cid) {
DEBUGP("altering call id from 0x%04x to 0x%04x\n",
ntohs(*(u_int16_t *)pptpReq + cid_off), ntohs(new_cid));
ntohs(REQ_CID(pptpReq, cid_off)), ntohs(new_cid));
if (ip_nat_mangle_tcp_packet(pskb, ct, ctinfo,
cid_off + sizeof(struct pptp_pkt_hdr) +
sizeof(struct PptpControlHeader),
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