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netfilter: nf_tproxy: fix possible non-linear access to transport header

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This patch fixes a silent out-of-bound read possibility that was present
because of the misuse of this function.

Mostly it was called with a struct udphdr *hp which had only the udphdr
part linearized by the skb_header_pointer, however
nf_tproxy_get_sock_v{4,6} uses it as a tcphdr pointer, so some reads for
tcp specific attributes may be invalid.

Fixes: a583636a83 ("inet: refactor inet[6]_lookup functions to take skb")
Signed-off-by: Máté Eckl <ecklm94@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Máté Eckl 2018-07-05 12:01:53 +02:00 committed by Pablo Neira Ayuso
parent d376bef9c2
commit 5711b4e893
4 changed files with 30 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/net/netfilter/nf_tproxy.h
View File

@ -64,7 +64,7 @@ nf_tproxy_handle_time_wait4(struct net *net, struct sk_buff *skb,
* belonging to established connections going through that one.
*/
struct sock *
nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb, void *hp,
nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb,
const u8 protocol,
const __be32 saddr, const __be32 daddr,
const __be16 sport, const __be16 dport,
@ -103,7 +103,7 @@ nf_tproxy_handle_time_wait6(struct sk_buff *skb, int tproto, int thoff,
struct sock *sk);
struct sock *
nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff, void *hp,
nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff,
const u8 protocol,
const struct in6_addr *saddr, const struct in6_addr *daddr,
const __be16 sport, const __be16 dport,

18
net/ipv4/netfilter/nf_tproxy_ipv4.c
View File

@ -37,7 +37,7 @@ nf_tproxy_handle_time_wait4(struct net *net, struct sk_buff *skb,
* to a listener socket if there's one */
struct sock *sk2;
sk2 = nf_tproxy_get_sock_v4(net, skb, hp, iph->protocol,
sk2 = nf_tproxy_get_sock_v4(net, skb, iph->protocol,
iph->saddr, laddr ? laddr : iph->daddr,
hp->source, lport ? lport : hp->dest,
skb->dev, NF_TPROXY_LOOKUP_LISTENER);
@ -71,7 +71,7 @@ __be32 nf_tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr)
EXPORT_SYMBOL_GPL(nf_tproxy_laddr4);
struct sock *
nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb, void *hp,
nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb,
const u8 protocol,
const __be32 saddr, const __be32 daddr,
const __be16 sport, const __be16 dport,
@ -79,16 +79,21 @@ nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb, void *hp,
const enum nf_tproxy_lookup_t lookup_type)
{
struct sock *sk;
struct tcphdr *tcph;
switch (protocol) {
case IPPROTO_TCP:
case IPPROTO_TCP: {
struct tcphdr _hdr, *hp;
hp = skb_header_pointer(skb, ip_hdrlen(skb),
sizeof(struct tcphdr), &_hdr);
if (hp == NULL)
return NULL;
switch (lookup_type) {
case NF_TPROXY_LOOKUP_LISTENER:
tcph = hp;
sk = inet_lookup_listener(net, &tcp_hashinfo, skb,
ip_hdrlen(skb) +
__tcp_hdrlen(tcph),
__tcp_hdrlen(hp),
saddr, sport,
daddr, dport,
in->ifindex, 0);
@ -110,6 +115,7 @@ nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb, void *hp,
BUG();
}
break;
}
case IPPROTO_UDP:
sk = udp4_lib_lookup(net, saddr, sport, daddr, dport,
in->ifindex);

18
net/ipv6/netfilter/nf_tproxy_ipv6.c
View File

@ -55,7 +55,7 @@ nf_tproxy_handle_time_wait6(struct sk_buff *skb, int tproto, int thoff,
* to a listener socket if there's one */
struct sock *sk2;
sk2 = nf_tproxy_get_sock_v6(net, skb, thoff, hp, tproto,
sk2 = nf_tproxy_get_sock_v6(net, skb, thoff, tproto,
&iph->saddr,
nf_tproxy_laddr6(skb, laddr, &iph->daddr),
hp->source,
@ -72,7 +72,7 @@ nf_tproxy_handle_time_wait6(struct sk_buff *skb, int tproto, int thoff,
EXPORT_SYMBOL_GPL(nf_tproxy_handle_time_wait6);
struct sock *
nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff, void *hp,
nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff,
const u8 protocol,
const struct in6_addr *saddr, const struct in6_addr *daddr,
const __be16 sport, const __be16 dport,
@ -80,15 +80,20 @@ nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff, void *hp,
const enum nf_tproxy_lookup_t lookup_type)
{
struct sock *sk;
struct tcphdr *tcph;
switch (protocol) {
case IPPROTO_TCP:
case IPPROTO_TCP: {
struct tcphdr _hdr, *hp;
hp = skb_header_pointer(skb, thoff,
sizeof(struct tcphdr), &_hdr);
if (hp == NULL)
return NULL;
switch (lookup_type) {
case NF_TPROXY_LOOKUP_LISTENER:
tcph = hp;
sk = inet6_lookup_listener(net, &tcp_hashinfo, skb,
thoff + __tcp_hdrlen(tcph),
thoff + __tcp_hdrlen(hp),
saddr, sport,
daddr, ntohs(dport),
in->ifindex, 0);
@ -110,6 +115,7 @@ nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff, void *hp,
BUG();
}
break;
}
case IPPROTO_UDP:
sk = udp6_lib_lookup(net, saddr, sport, daddr, dport,
in->ifindex);

8
net/netfilter/xt_TPROXY.c
View File

@ -61,7 +61,7 @@ tproxy_tg4(struct net *net, struct sk_buff *skb, __be32 laddr, __be16 lport,
* addresses, this happens if the redirect already happened
* and the current packet belongs to an already established
* connection */
sk = nf_tproxy_get_sock_v4(net, skb, hp, iph->protocol,
sk = nf_tproxy_get_sock_v4(net, skb, iph->protocol,
iph->saddr, iph->daddr,
hp->source, hp->dest,
skb->dev, NF_TPROXY_LOOKUP_ESTABLISHED);
@ -77,7 +77,7 @@ tproxy_tg4(struct net *net, struct sk_buff *skb, __be32 laddr, __be16 lport,
else if (!sk)
/* no, there's no established connection, check if
* there's a listener on the redirected addr/port */
sk = nf_tproxy_get_sock_v4(net, skb, hp, iph->protocol,
sk = nf_tproxy_get_sock_v4(net, skb, iph->protocol,
iph->saddr, laddr,
hp->source, lport,
skb->dev, NF_TPROXY_LOOKUP_LISTENER);
@ -150,7 +150,7 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
* addresses, this happens if the redirect already happened
* and the current packet belongs to an already established
* connection */
sk = nf_tproxy_get_sock_v6(xt_net(par), skb, thoff, hp, tproto,
sk = nf_tproxy_get_sock_v6(xt_net(par), skb, thoff, tproto,
&iph->saddr, &iph->daddr,
hp->source, hp->dest,
xt_in(par), NF_TPROXY_LOOKUP_ESTABLISHED);
@ -171,7 +171,7 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
else if (!sk)
/* no there's no established connection, check if
* there's a listener on the redirected addr/port */
sk = nf_tproxy_get_sock_v6(xt_net(par), skb, thoff, hp,
sk = nf_tproxy_get_sock_v6(xt_net(par), skb, thoff,
tproto, &iph->saddr, laddr,
hp->source, lport,
xt_in(par), NF_TPROXY_LOOKUP_LISTENER);