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Message-Id: <20200525215420.2290-4-pablo@netfilter.org>
Date: Mon, 25 May 2020 23:54:18 +0200
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net, netdev@...r.kernel.org, kuba@...nel.org
Subject: [PATCH 3/5] 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: f09943fefe6b ("[NETFILTER]: nf_conntrack/nf_nat: add PPTP helper port")
Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
include/linux/netfilter/nf_conntrack_pptp.h | 2 +-
net/ipv4/netfilter/nf_nat_pptp.c | 7 +--
net/netfilter/nf_conntrack_pptp.c | 62 ++++++++++++---------
3 files changed, 38 insertions(+), 33 deletions(-)
diff --git a/include/linux/netfilter/nf_conntrack_pptp.h b/include/linux/netfilter/nf_conntrack_pptp.h
index fcc409de31a4..6a4ff6d5ebc2 100644
--- a/include/linux/netfilter/nf_conntrack_pptp.h
+++ b/include/linux/netfilter/nf_conntrack_pptp.h
@@ -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 {
diff --git a/net/ipv4/netfilter/nf_nat_pptp.c b/net/ipv4/netfilter/nf_nat_pptp.c
index 3c25a467b3ef..7afde8828b4c 100644
--- a/net/ipv4/netfilter/nf_nat_pptp.c
+++ b/net/ipv4/netfilter/nf_nat_pptp.c
@@ -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:
diff --git a/net/netfilter/nf_conntrack_pptp.c b/net/netfilter/nf_conntrack_pptp.c
index a971183f11af..7ad247784cfa 100644
--- a/net/netfilter/nf_conntrack_pptp.c
+++ b/net/netfilter/nf_conntrack_pptp.c
@@ -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;
--
2.20.1
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