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[NETFILTER]: PPTP conntrack: consolidate header size checks
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Also make sure not to pass undersized messages to the NAT helper.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Patrick McHardy authored and David S. Miller committed Sep 22, 2006
1 parent cf9f815 commit a107340
Showing 1 changed file with 22 additions and 43 deletions.
65 changes: 22 additions & 43 deletions net/ipv4/netfilter/ip_conntrack_helper_pptp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -291,6 +291,22 @@ exp_gre(struct ip_conntrack *ct,
goto out_put_both;
}

static const unsigned int pptp_msg_size[] = {
[PPTP_START_SESSION_REQUEST] = sizeof(struct PptpStartSessionRequest),
[PPTP_START_SESSION_REPLY] = sizeof(struct PptpStartSessionReply),
[PPTP_STOP_SESSION_REQUEST] = sizeof(struct PptpStopSessionRequest),
[PPTP_STOP_SESSION_REPLY] = sizeof(struct PptpStopSessionReply),
[PPTP_OUT_CALL_REQUEST] = sizeof(struct PptpOutCallRequest),
[PPTP_OUT_CALL_REPLY] = sizeof(struct PptpOutCallReply),
[PPTP_IN_CALL_REQUEST] = sizeof(struct PptpInCallRequest),
[PPTP_IN_CALL_REPLY] = sizeof(struct PptpInCallReply),
[PPTP_IN_CALL_CONNECT] = sizeof(struct PptpInCallConnected),
[PPTP_CALL_CLEAR_REQUEST] = sizeof(struct PptpClearCallRequest),
[PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify),
[PPTP_WAN_ERROR_NOTIFY] = sizeof(struct PptpWanErrorNotify),
[PPTP_SET_LINK_INFO] = sizeof(struct PptpSetLinkInfo),
};

static inline int
pptp_inbound_pkt(struct sk_buff **pskb,
struct tcphdr *tcph,
Expand Down Expand Up @@ -326,13 +342,11 @@ pptp_inbound_pkt(struct sk_buff **pskb,
msg = ntohs(ctlh->messageType);
DEBUGP("inbound control message %s\n", pptp_msg_name[msg]);

if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg])
return NF_ACCEPT;

switch (msg) {
case PPTP_START_SESSION_REPLY:
if (reqlen < sizeof(_pptpReq.srep)) {
DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
break;
}

/* server confirms new control session */
if (info->sstate < PPTP_SESSION_REQUESTED) {
DEBUGP("%s without START_SESS_REQUEST\n",
Expand All @@ -346,11 +360,6 @@ pptp_inbound_pkt(struct sk_buff **pskb,
break;

case PPTP_STOP_SESSION_REPLY:
if (reqlen < sizeof(_pptpReq.strep)) {
DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
break;
}

/* server confirms end of control session */
if (info->sstate > PPTP_SESSION_STOPREQ) {
DEBUGP("%s without STOP_SESS_REQUEST\n",
Expand All @@ -364,11 +373,6 @@ pptp_inbound_pkt(struct sk_buff **pskb,
break;

case PPTP_OUT_CALL_REPLY:
if (reqlen < sizeof(_pptpReq.ocack)) {
DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
break;
}

/* server accepted call, we now expect GRE frames */
if (info->sstate != PPTP_SESSION_CONFIRMED) {
DEBUGP("%s but no session\n", pptp_msg_name[msg]);
Expand Down Expand Up @@ -404,11 +408,6 @@ pptp_inbound_pkt(struct sk_buff **pskb,
break;

case PPTP_IN_CALL_REQUEST:
if (reqlen < sizeof(_pptpReq.icack)) {
DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
break;
}

/* server tells us about incoming call request */
if (info->sstate != PPTP_SESSION_CONFIRMED) {
DEBUGP("%s but no session\n", pptp_msg_name[msg]);
Expand All @@ -421,11 +420,6 @@ pptp_inbound_pkt(struct sk_buff **pskb,
break;

case PPTP_IN_CALL_CONNECT:
if (reqlen < sizeof(_pptpReq.iccon)) {
DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
break;
}

/* server tells us about incoming call established */
if (info->sstate != PPTP_SESSION_CONFIRMED) {
DEBUGP("%s but no session\n", pptp_msg_name[msg]);
Expand Down Expand Up @@ -455,11 +449,6 @@ pptp_inbound_pkt(struct sk_buff **pskb,
break;

case PPTP_CALL_DISCONNECT_NOTIFY:
if (reqlen < sizeof(_pptpReq.disc)) {
DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
break;
}

/* server confirms disconnect */
cid = pptpReq->disc.callID;
DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
Expand All @@ -470,8 +459,6 @@ pptp_inbound_pkt(struct sk_buff **pskb,
break;

case PPTP_WAN_ERROR_NOTIFY:
break;

case PPTP_ECHO_REQUEST:
case PPTP_ECHO_REPLY:
/* I don't have to explain these ;) */
Expand Down Expand Up @@ -522,6 +509,9 @@ pptp_outbound_pkt(struct sk_buff **pskb,
msg = ntohs(ctlh->messageType);
DEBUGP("outbound control message %s\n", pptp_msg_name[msg]);

if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg])
return NF_ACCEPT;

switch (msg) {
case PPTP_START_SESSION_REQUEST:
/* client requests for new control session */
Expand All @@ -537,11 +527,6 @@ pptp_outbound_pkt(struct sk_buff **pskb,
break;

case PPTP_OUT_CALL_REQUEST:
if (reqlen < sizeof(_pptpReq.ocreq)) {
DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
break;
}

/* client initiating connection to server */
if (info->sstate != PPTP_SESSION_CONFIRMED) {
DEBUGP("%s but no session\n",
Expand All @@ -555,11 +540,6 @@ pptp_outbound_pkt(struct sk_buff **pskb,
info->pns_call_id = cid;
break;
case PPTP_IN_CALL_REPLY:
if (reqlen < sizeof(_pptpReq.icack)) {
DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
break;
}

/* client answers incoming call */
if (info->cstate != PPTP_CALL_IN_REQ
&& info->cstate != PPTP_CALL_IN_REP) {
Expand Down Expand Up @@ -595,7 +575,6 @@ pptp_outbound_pkt(struct sk_buff **pskb,
info->cstate = PPTP_CALL_CLEAR_REQ;
break;
case PPTP_SET_LINK_INFO:
break;
case PPTP_ECHO_REQUEST:
case PPTP_ECHO_REPLY:
/* I don't have to explain these ;) */
Expand Down

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