kernel: backport flow offload pppoe fix

[openwrt/openwrt.git] / target / linux / generic / backport-6.6 / 740-v6.9-01-netfilter-flowtable-validate-pppoe-header.patch

diff --git a/target/linux/generic/backport-6.6/740-v6.9-01-netfilter-flowtable-validate-pppoe-header.patch b/target/linux/generic/backport-6.6/740-v6.9-01-netfilter-flowtable-validate-pppoe-header.patch
new file mode 100644 (file)
index 0000000..8a8773b
--- /dev/null
+++ b/target/linux/generic/backport-6.6/740-v6.9-01-netfilter-flowtable-validate-pppoe-header.patch
@@ -0,0 +1,87 @@
+From: Pablo Neira Ayuso <pablo@netfilter.org>
+Date: Thu, 11 Apr 2024 13:28:59 +0200
+Subject: [PATCH] netfilter: flowtable: validate pppoe header
+
+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: 72efd585f714 ("netfilter: flowtable: add pppoe support")
+Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
+---
+
+--- a/include/net/netfilter/nf_flow_table.h
++++ b/include/net/netfilter/nf_flow_table.h
+@@ -335,7 +335,7 @@ int nf_flow_rule_route_ipv6(struct net *
+ 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
+       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)     \
+--- a/net/netfilter/nf_flow_table_inet.c
++++ b/net/netfilter/nf_flow_table_inet.c
+@@ -21,7 +21,8 @@ nf_flow_offload_inet_hook(void *priv, st
+               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;
+--- a/net/netfilter/nf_flow_table_ip.c
++++ b/net/netfilter/nf_flow_table_ip.c
+@@ -273,10 +273,11 @@ static unsigned int nf_flow_xmit_xfrm(st
+       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(c
+               }
+               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_
+                       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;