Author: emaste
Date: Tue May 12 16:33:04 2020
New Revision: 360967
URL: https://svnweb.freebsd.org/changeset/base/360967
Log:
libalias: validate packet lengths before accessing headers
admbugs: 956
Submitted by: ae
Reported by: Lucas Leong (@_wmliang_) of Trend Micro Zero Day Initiative
Reported by: Vishnu working with Trend Micro Zero Day Initiative
Security: FreeBSD-SA-20:12.libalias
Modified:
head/sys/netinet/libalias/alias.c
Modified: head/sys/netinet/libalias/alias.c
==============================================================================
--- head/sys/netinet/libalias/alias.c Tue May 12 16:10:07 2020
(r360966)
+++ head/sys/netinet/libalias/alias.c Tue May 12 16:33:04 2020
(r360967)
@@ -442,10 +442,15 @@ fragment contained in ICMP data section */
static int
IcmpAliasIn(struct libalias *la, struct ip *pip)
{
- int iresult;
struct icmp *ic;
+ int dlen, iresult;
LIBALIAS_LOCK_ASSERT(la);
+
+ dlen = ntohs(pip->ip_len) - (pip->ip_hl << 2);
+ if (dlen < ICMP_MINLEN)
+ return (PKT_ALIAS_IGNORED);
+
/* Return if proxy-only mode is enabled */
if (la->packetAliasMode & PKT_ALIAS_PROXY_ONLY)
return (PKT_ALIAS_OK);
@@ -464,6 +469,9 @@ IcmpAliasIn(struct libalias *la, struct ip *pip)
case ICMP_SOURCEQUENCH:
case ICMP_TIMXCEED:
case ICMP_PARAMPROB:
+ if (dlen < ICMP_ADVLENMIN ||
+ dlen < ICMP_ADVLEN(ic))
+ return (PKT_ALIAS_IGNORED);
iresult = IcmpAliasIn2(la, pip);
break;
case ICMP_ECHO:
@@ -732,10 +740,17 @@ UdpAliasIn(struct libalias *la, struct ip *pip)
{
struct udphdr *ud;
struct alias_link *lnk;
+ int dlen;
LIBALIAS_LOCK_ASSERT(la);
+ dlen = ntohs(pip->ip_len) - (pip->ip_hl << 2);
+ if (dlen < sizeof(struct udphdr))
+ return (PKT_ALIAS_IGNORED);
+
ud = (struct udphdr *)ip_next(pip);
+ if (dlen < ntohs(ud->uh_ulen))
+ return (PKT_ALIAS_IGNORED);
lnk = FindUdpTcpIn(la, pip->ip_src, pip->ip_dst,
ud->uh_sport, ud->uh_dport,
@@ -824,12 +839,19 @@ UdpAliasOut(struct libalias *la, struct ip *pip, int m
u_short dest_port;
u_short proxy_server_port;
int proxy_type;
- int error;
+ int dlen, error;
LIBALIAS_LOCK_ASSERT(la);
/* Return if proxy-only mode is enabled and not proxyrule found.*/
+ dlen = ntohs(pip->ip_len) - (pip->ip_hl << 2);
+ if (dlen < sizeof(struct udphdr))
+ return (PKT_ALIAS_IGNORED);
+
ud = (struct udphdr *)ip_next(pip);
+ if (dlen < ntohs(ud->uh_ulen))
+ return (PKT_ALIAS_IGNORED);
+
proxy_type = ProxyCheck(la, &proxy_server_address,
&proxy_server_port, pip->ip_src, pip->ip_dst,
ud->uh_dport, pip->ip_p);
@@ -922,8 +944,13 @@ TcpAliasIn(struct libalias *la, struct ip *pip)
{
struct tcphdr *tc;
struct alias_link *lnk;
+ int dlen;
LIBALIAS_LOCK_ASSERT(la);
+
+ dlen = ntohs(pip->ip_len) - (pip->ip_hl << 2);
+ if (dlen < sizeof(struct tcphdr))
+ return (PKT_ALIAS_IGNORED);
tc = (struct tcphdr *)ip_next(pip);
lnk = FindUdpTcpIn(la, pip->ip_src, pip->ip_dst,
@@ -1042,7 +1069,7 @@ TcpAliasIn(struct libalias *la, struct ip *pip)
static int
TcpAliasOut(struct libalias *la, struct ip *pip, int maxpacketsize, int create)
{
- int proxy_type, error;
+ int dlen, proxy_type, error;
u_short dest_port;
u_short proxy_server_port;
struct in_addr dest_address;
@@ -1051,6 +1078,10 @@ TcpAliasOut(struct libalias *la, struct ip *pip, int m
struct alias_link *lnk;
LIBALIAS_LOCK_ASSERT(la);
+
+ dlen = ntohs(pip->ip_len) - (pip->ip_hl << 2);
+ if (dlen < sizeof(struct tcphdr))
+ return (PKT_ALIAS_IGNORED);
tc = (struct tcphdr *)ip_next(pip);
if (create)
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