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libalias: validate packet lengths before accessing headers

Browse Source 
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
This commit is contained in:
Ed Maste 2020-05-12 16:33:04 +00:00
parent 318825636c
commit 6461c83e09
1 changed files with 34 additions and 3 deletions
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37
sys/netinet/libalias/alias.c
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@ -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 maxpacketsize, int create)
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 maxpacketsize, int create)
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)