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netfilter: flowtable: validate pppoe header

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[ Upstream commit 87b3593bed ]

Ensure there is sufficient room to access the protocol field of the
PPPoe header. Validate it once before the flowtable lookup, then use a
helper function to access protocol field.

Reported-by: syzbot+b6f07e1c07ef40199081@syzkaller.appspotmail.com
Fixes: 72efd585f7 ("netfilter: flowtable: add pppoe support")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Pablo Neira Ayuso 2024-04-09 13:47:33 +02:00 committed by Greg Kroah-Hartman
parent ebf7c9746f
commit a2471d2710
3 changed files with 18 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
include/net/netfilter/nf_flow_table.h
View File

@ -335,7 +335,7 @@ int nf_flow_rule_route_ipv6(struct net *net, struct flow_offload *flow,
int nf_flow_table_offload_init(void);
void nf_flow_table_offload_exit(void);
static inline __be16 nf_flow_pppoe_proto(const struct sk_buff *skb)
static inline __be16 __nf_flow_pppoe_proto(const struct sk_buff *skb)
{
__be16 proto;
@ -351,6 +351,16 @@ static inline __be16 nf_flow_pppoe_proto(const struct sk_buff *skb)
return 0;
}
static inline bool nf_flow_pppoe_proto(struct sk_buff *skb, __be16 *inner_proto)
{
if (!pskb_may_pull(skb, PPPOE_SES_HLEN))
return false;
*inner_proto = __nf_flow_pppoe_proto(skb);
return true;
}
#define NF_FLOW_TABLE_STAT_INC(net, count) __this_cpu_inc((net)->ft.stat->count)
#define NF_FLOW_TABLE_STAT_DEC(net, count) __this_cpu_dec((net)->ft.stat->count)
#define NF_FLOW_TABLE_STAT_INC_ATOMIC(net, count) \

3
net/netfilter/nf_flow_table_inet.c
View File

@ -21,7 +21,8 @@ nf_flow_offload_inet_hook(void *priv, struct sk_buff *skb,
proto = veth->h_vlan_encapsulated_proto;
break;
case htons(ETH_P_PPP_SES):
proto = nf_flow_pppoe_proto(skb);
if (!nf_flow_pppoe_proto(skb, &proto))
return NF_ACCEPT;
break;
default:
proto = skb->protocol;

8
net/netfilter/nf_flow_table_ip.c
View File

@ -273,10 +273,11 @@ static unsigned int nf_flow_xmit_xfrm(struct sk_buff *skb,
return NF_STOLEN;
}
static bool nf_flow_skb_encap_protocol(const struct sk_buff *skb, __be16 proto,
static bool nf_flow_skb_encap_protocol(struct sk_buff *skb, __be16 proto,
u32 *offset)
{
struct vlan_ethhdr *veth;
__be16 inner_proto;
switch (skb->protocol) {
case htons(ETH_P_8021Q):
@ -287,7 +288,8 @@ static bool nf_flow_skb_encap_protocol(const struct sk_buff *skb, __be16 proto,
}
break;
case htons(ETH_P_PPP_SES):
if (nf_flow_pppoe_proto(skb) == proto) {
if (nf_flow_pppoe_proto(skb, &inner_proto) &&
inner_proto == proto) {
*offset += PPPOE_SES_HLEN;
return true;
}
@ -316,7 +318,7 @@ static void nf_flow_encap_pop(struct sk_buff *skb,
skb_reset_network_header(skb);
break;
case htons(ETH_P_PPP_SES):
skb->protocol = nf_flow_pppoe_proto(skb);
skb->protocol = __nf_flow_pppoe_proto(skb);
skb_pull(skb, PPPOE_SES_HLEN);
skb_reset_network_header(skb);
break;