86 lines
2.6 KiB
Diff
86 lines
2.6 KiB
Diff
From: Pablo Neira Ayuso <pablo@netfilter.org>
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Date: Thu, 11 Apr 2024 13:28:59 +0200
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Subject: [PATCH] netfilter: flowtable: validate pppoe header
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Ensure there is sufficient room to access the protocol field of the
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PPPoe header. Validate it once before the flowtable lookup, then use a
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helper function to access protocol field.
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Reported-by: syzbot+b6f07e1c07ef40199081@syzkaller.appspotmail.com
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Fixes: 72efd585f714 ("netfilter: flowtable: add pppoe support")
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Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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---
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--- a/include/net/netfilter/nf_flow_table.h
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+++ b/include/net/netfilter/nf_flow_table.h
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@@ -318,7 +318,7 @@ int nf_flow_rule_route_ipv6(struct net *
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int nf_flow_table_offload_init(void);
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void nf_flow_table_offload_exit(void);
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-static inline __be16 nf_flow_pppoe_proto(const struct sk_buff *skb)
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+static inline __be16 __nf_flow_pppoe_proto(const struct sk_buff *skb)
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{
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__be16 proto;
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@@ -334,4 +334,14 @@ static inline __be16 nf_flow_pppoe_proto
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return 0;
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}
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+static inline bool nf_flow_pppoe_proto(struct sk_buff *skb, __be16 *inner_proto)
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+{
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+ if (!pskb_may_pull(skb, PPPOE_SES_HLEN))
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+ return false;
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+
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+ *inner_proto = __nf_flow_pppoe_proto(skb);
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+
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+ return true;
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+}
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+
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#endif /* _NF_FLOW_TABLE_H */
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--- a/net/netfilter/nf_flow_table_inet.c
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+++ b/net/netfilter/nf_flow_table_inet.c
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@@ -21,7 +21,8 @@ nf_flow_offload_inet_hook(void *priv, st
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proto = veth->h_vlan_encapsulated_proto;
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break;
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case htons(ETH_P_PPP_SES):
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- proto = nf_flow_pppoe_proto(skb);
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+ if (!nf_flow_pppoe_proto(skb, &proto))
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+ return NF_ACCEPT;
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break;
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default:
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proto = skb->protocol;
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--- a/net/netfilter/nf_flow_table_ip.c
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+++ b/net/netfilter/nf_flow_table_ip.c
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@@ -246,10 +246,11 @@ static unsigned int nf_flow_xmit_xfrm(st
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return NF_STOLEN;
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}
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-static bool nf_flow_skb_encap_protocol(const struct sk_buff *skb, __be16 proto,
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+static bool nf_flow_skb_encap_protocol(struct sk_buff *skb, __be16 proto,
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u32 *offset)
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{
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struct vlan_ethhdr *veth;
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+ __be16 inner_proto;
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switch (skb->protocol) {
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case htons(ETH_P_8021Q):
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@@ -260,7 +261,8 @@ static bool nf_flow_skb_encap_protocol(c
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}
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break;
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case htons(ETH_P_PPP_SES):
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- if (nf_flow_pppoe_proto(skb) == proto) {
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+ if (nf_flow_pppoe_proto(skb, &inner_proto) &&
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+ inner_proto == proto) {
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*offset += PPPOE_SES_HLEN;
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return true;
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}
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@@ -289,7 +291,7 @@ static void nf_flow_encap_pop(struct sk_
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skb_reset_network_header(skb);
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break;
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case htons(ETH_P_PPP_SES):
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- skb->protocol = nf_flow_pppoe_proto(skb);
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+ skb->protocol = __nf_flow_pppoe_proto(skb);
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skb_pull(skb, PPPOE_SES_HLEN);
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skb_reset_network_header(skb);
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break;
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