Commit 4c559f15 authored by Pablo Neira Ayuso's avatar Pablo Neira Ayuso
Browse files

netfilter: nf_conntrack_pptp: prevent buffer overflows in debug code 



Dan Carpenter says: "Smatch complains that the value for "cmd" comes
from the network and can't be trusted."

Add pptp_msg_name() helper function that checks for the array boundary.

Fixes: f09943fe ("[NETFILTER]: nf_conntrack/nf_nat: add PPTP helper port")
Reported-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent a164b95a

include/linux/netfilter/nf_conntrack_pptp.h

+1 −1
Original line number Diff line number Diff line
@@ -10,7 +10,7 @@ 
#include <net/netfilter/nf_conntrack_expect.h>

#include <uapi/linux/netfilter/nf_conntrack_tuple_common.h>



extern const char *const pptp_msg_name[];

extern const char *const pptp_msg_name(u_int16_t msg);



/* state of the control session */

enum pptp_ctrlsess_state {

net/ipv4/netfilter/nf_nat_pptp.c

+2 −5
Original line number Diff line number Diff line
@@ -166,8 +166,7 @@ pptp_outbound_pkt(struct sk_buff *skb, 
		break;

	default:

		pr_debug("unknown outbound packet 0x%04x:%s\n", msg,

			 msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] :

					       pptp_msg_name[0]);

			 pptp_msg_name(msg));

		fallthrough;

	case PPTP_SET_LINK_INFO:

		/* only need to NAT in case PAC is behind NAT box */
@@ -268,9 +267,7 @@ pptp_inbound_pkt(struct sk_buff *skb, 
		pcid_off = offsetof(union pptp_ctrl_union, setlink.peersCallID);

		break;

	default:

		pr_debug("unknown inbound packet %s\n",

			 msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] :

					       pptp_msg_name[0]);

		pr_debug("unknown inbound packet %s\n", pptp_msg_name(msg));

		fallthrough;

	case PPTP_START_SESSION_REQUEST:

	case PPTP_START_SESSION_REPLY:

net/netfilter/nf_conntrack_pptp.c

+35 −27
Original line number Diff line number Diff line
@@ -72,24 +72,32 @@ EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_expectfn); 


#if defined(DEBUG) || defined(CONFIG_DYNAMIC_DEBUG)

/* PptpControlMessageType names */

const char *const pptp_msg_name[] = {

	"UNKNOWN_MESSAGE",

	"START_SESSION_REQUEST",

	"START_SESSION_REPLY",

	"STOP_SESSION_REQUEST",

	"STOP_SESSION_REPLY",

	"ECHO_REQUEST",

	"ECHO_REPLY",

	"OUT_CALL_REQUEST",

	"OUT_CALL_REPLY",

	"IN_CALL_REQUEST",

	"IN_CALL_REPLY",

	"IN_CALL_CONNECT",

	"CALL_CLEAR_REQUEST",

	"CALL_DISCONNECT_NOTIFY",

	"WAN_ERROR_NOTIFY",

	"SET_LINK_INFO"

static const char *const pptp_msg_name_array[PPTP_MSG_MAX + 1] = {

	[0]				= "UNKNOWN_MESSAGE",

	[PPTP_START_SESSION_REQUEST]	= "START_SESSION_REQUEST",

	[PPTP_START_SESSION_REPLY]	= "START_SESSION_REPLY",

	[PPTP_STOP_SESSION_REQUEST]	= "STOP_SESSION_REQUEST",

	[PPTP_STOP_SESSION_REPLY]	= "STOP_SESSION_REPLY",

	[PPTP_ECHO_REQUEST]		= "ECHO_REQUEST",

	[PPTP_ECHO_REPLY]		= "ECHO_REPLY",

	[PPTP_OUT_CALL_REQUEST]		= "OUT_CALL_REQUEST",

	[PPTP_OUT_CALL_REPLY]		= "OUT_CALL_REPLY",

	[PPTP_IN_CALL_REQUEST]		= "IN_CALL_REQUEST",

	[PPTP_IN_CALL_REPLY]		= "IN_CALL_REPLY",

	[PPTP_IN_CALL_CONNECT]		= "IN_CALL_CONNECT",

	[PPTP_CALL_CLEAR_REQUEST]	= "CALL_CLEAR_REQUEST",

	[PPTP_CALL_DISCONNECT_NOTIFY]	= "CALL_DISCONNECT_NOTIFY",

	[PPTP_WAN_ERROR_NOTIFY]		= "WAN_ERROR_NOTIFY",

	[PPTP_SET_LINK_INFO]		= "SET_LINK_INFO"

};



const char *const pptp_msg_name(u_int16_t msg)

{

	if (msg > PPTP_MSG_MAX)

		return pptp_msg_name_array[0];



	return pptp_msg_name_array[msg];

}

EXPORT_SYMBOL(pptp_msg_name);

#endif
@@ -276,7 +284,7 @@ pptp_inbound_pkt(struct sk_buff *skb, unsigned int protoff, 
	typeof(nf_nat_pptp_hook_inbound) nf_nat_pptp_inbound;



	msg = ntohs(ctlh->messageType);

	pr_debug("inbound control message %s\n", pptp_msg_name[msg]);

	pr_debug("inbound control message %s\n", pptp_msg_name(msg));



	switch (msg) {

	case PPTP_START_SESSION_REPLY:
@@ -311,7 +319,7 @@ pptp_inbound_pkt(struct sk_buff *skb, unsigned int protoff, 
		pcid = pptpReq->ocack.peersCallID;

		if (info->pns_call_id != pcid)

			goto invalid;

		pr_debug("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg],

		pr_debug("%s, CID=%X, PCID=%X\n", pptp_msg_name(msg),

			 ntohs(cid), ntohs(pcid));



		if (pptpReq->ocack.resultCode == PPTP_OUTCALL_CONNECT) {
@@ -328,7 +336,7 @@ pptp_inbound_pkt(struct sk_buff *skb, unsigned int protoff, 
			goto invalid;



		cid = pptpReq->icreq.callID;

		pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));

		pr_debug("%s, CID=%X\n", pptp_msg_name(msg), ntohs(cid));

		info->cstate = PPTP_CALL_IN_REQ;

		info->pac_call_id = cid;

		break;
@@ -347,7 +355,7 @@ pptp_inbound_pkt(struct sk_buff *skb, unsigned int protoff, 
		if (info->pns_call_id != pcid)

			goto invalid;



		pr_debug("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid));

		pr_debug("%s, PCID=%X\n", pptp_msg_name(msg), ntohs(pcid));

		info->cstate = PPTP_CALL_IN_CONF;



		/* we expect a GRE connection from PAC to PNS */
@@ -357,7 +365,7 @@ pptp_inbound_pkt(struct sk_buff *skb, unsigned int protoff, 
	case PPTP_CALL_DISCONNECT_NOTIFY:

		/* server confirms disconnect */

		cid = pptpReq->disc.callID;

		pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));

		pr_debug("%s, CID=%X\n", pptp_msg_name(msg), ntohs(cid));

		info->cstate = PPTP_CALL_NONE;



		/* untrack this call id, unexpect GRE packets */
@@ -384,7 +392,7 @@ pptp_inbound_pkt(struct sk_buff *skb, unsigned int protoff, 
invalid:

	pr_debug("invalid %s: type=%d cid=%u pcid=%u "

		 "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",

		 msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0],

		 pptp_msg_name(msg),

		 msg, ntohs(cid), ntohs(pcid),  info->cstate, info->sstate,

		 ntohs(info->pns_call_id), ntohs(info->pac_call_id));

	return NF_ACCEPT;
@@ -404,7 +412,7 @@ pptp_outbound_pkt(struct sk_buff *skb, unsigned int protoff, 
	typeof(nf_nat_pptp_hook_outbound) nf_nat_pptp_outbound;



	msg = ntohs(ctlh->messageType);

	pr_debug("outbound control message %s\n", pptp_msg_name[msg]);

	pr_debug("outbound control message %s\n", pptp_msg_name(msg));



	switch (msg) {

	case PPTP_START_SESSION_REQUEST:
@@ -426,7 +434,7 @@ pptp_outbound_pkt(struct sk_buff *skb, unsigned int protoff, 
		info->cstate = PPTP_CALL_OUT_REQ;

		/* track PNS call id */

		cid = pptpReq->ocreq.callID;

		pr_debug("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));

		pr_debug("%s, CID=%X\n", pptp_msg_name(msg), ntohs(cid));

		info->pns_call_id = cid;

		break;
@@ -440,7 +448,7 @@ pptp_outbound_pkt(struct sk_buff *skb, unsigned int protoff, 
		pcid = pptpReq->icack.peersCallID;

		if (info->pac_call_id != pcid)

			goto invalid;

		pr_debug("%s, CID=%X PCID=%X\n", pptp_msg_name[msg],

		pr_debug("%s, CID=%X PCID=%X\n", pptp_msg_name(msg),

			 ntohs(cid), ntohs(pcid));



		if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) {
@@ -480,7 +488,7 @@ pptp_outbound_pkt(struct sk_buff *skb, unsigned int protoff, 
invalid:

	pr_debug("invalid %s: type=%d cid=%u pcid=%u "

		 "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",

		 msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0],

		 pptp_msg_name(msg),

		 msg, ntohs(cid), ntohs(pcid),  info->cstate, info->sstate,

		 ntohs(info->pns_call_id), ntohs(info->pac_call_id));

	return NF_ACCEPT;

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