From 1eacdd71b3436b54d5fc8218c4bb0187d92a6892 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Tue, 20 Aug 2024 09:54:30 +0200 Subject: [PATCH 1/3] netfilter: nft_counter: Disable BH in nft_counter_offload_stats(). The sequence counter nft_counter_seq is a per-CPU counter. There is no lock associated with it. nft_counter_do_eval() is using the same counter and disables BH which suggest that it can be invoked from a softirq. This in turn means that nft_counter_offload_stats(), which disables only preemption, can be interrupted by nft_counter_do_eval() leading to two writer for one seqcount_t. This can lead to loosing stats or reading statistics while they are updated. Disable BH during stats update in nft_counter_offload_stats() to ensure one writer at a time. Fixes: b72920f6e4a9d ("netfilter: nftables: counter hardware offload support") Signed-off-by: Sebastian Andrzej Siewior Reviewed-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nft_counter.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/netfilter/nft_counter.c b/net/netfilter/nft_counter.c index 291ed2026367ec..16f40b503d3798 100644 --- a/net/netfilter/nft_counter.c +++ b/net/netfilter/nft_counter.c @@ -265,7 +265,7 @@ static void nft_counter_offload_stats(struct nft_expr *expr, struct nft_counter *this_cpu; seqcount_t *myseq; - preempt_disable(); + local_bh_disable(); this_cpu = this_cpu_ptr(priv->counter); myseq = this_cpu_ptr(&nft_counter_seq); @@ -273,7 +273,7 @@ static void nft_counter_offload_stats(struct nft_expr *expr, this_cpu->packets += stats->pkts; this_cpu->bytes += stats->bytes; write_seqcount_end(myseq); - preempt_enable(); + local_bh_enable(); } void nft_counter_init_seqcount(void) From a0b39e2dc7017ac667b70bdeee5293e410fab2fb Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Tue, 20 Aug 2024 09:54:31 +0200 Subject: [PATCH 2/3] netfilter: nft_counter: Synchronize nft_counter_reset() against reader. nft_counter_reset() resets the counter by subtracting the previously retrieved value from the counter. This is a write operation on the counter and as such it requires to be performed with a write sequence of nft_counter_seq to serialize against its possible reader. Update the packets/ bytes within write-sequence of nft_counter_seq. Fixes: d84701ecbcd6a ("netfilter: nft_counter: rework atomic dump and reset") Signed-off-by: Sebastian Andrzej Siewior Reviewed-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nft_counter.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/netfilter/nft_counter.c b/net/netfilter/nft_counter.c index 16f40b503d3798..eab0dc66bee6bd 100644 --- a/net/netfilter/nft_counter.c +++ b/net/netfilter/nft_counter.c @@ -107,11 +107,16 @@ static void nft_counter_reset(struct nft_counter_percpu_priv *priv, struct nft_counter *total) { struct nft_counter *this_cpu; + seqcount_t *myseq; local_bh_disable(); this_cpu = this_cpu_ptr(priv->counter); + myseq = this_cpu_ptr(&nft_counter_seq); + + write_seqcount_begin(myseq); this_cpu->packets -= total->packets; this_cpu->bytes -= total->bytes; + write_seqcount_end(myseq); local_bh_enable(); } From 6ea14ccb60c8ab829349979b22b58a941ec4a3ee Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Tue, 13 Aug 2024 12:39:46 +0200 Subject: [PATCH 3/3] netfilter: flowtable: validate vlan header Ensure there is sufficient room to access the protocol field of the VLAN header, validate it once before the flowtable lookup. ===================================================== BUG: KMSAN: uninit-value in nf_flow_offload_inet_hook+0x45a/0x5f0 net/netfilter/nf_flow_table_inet.c:32 nf_flow_offload_inet_hook+0x45a/0x5f0 net/netfilter/nf_flow_table_inet.c:32 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline] nf_hook_slow+0xf4/0x400 net/netfilter/core.c:626 nf_hook_ingress include/linux/netfilter_netdev.h:34 [inline] nf_ingress net/core/dev.c:5440 [inline] Fixes: 4cd91f7c290f ("netfilter: flowtable: add vlan support") Reported-by: syzbot+8407d9bb88cd4c6bf61a@syzkaller.appspotmail.com Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_flow_table_inet.c | 3 +++ net/netfilter/nf_flow_table_ip.c | 3 +++ 2 files changed, 6 insertions(+) diff --git a/net/netfilter/nf_flow_table_inet.c b/net/netfilter/nf_flow_table_inet.c index 88787b45e30d6b..8b541a08034206 100644 --- a/net/netfilter/nf_flow_table_inet.c +++ b/net/netfilter/nf_flow_table_inet.c @@ -17,6 +17,9 @@ nf_flow_offload_inet_hook(void *priv, struct sk_buff *skb, switch (skb->protocol) { case htons(ETH_P_8021Q): + if (!pskb_may_pull(skb, skb_mac_offset(skb) + sizeof(*veth))) + return NF_ACCEPT; + veth = (struct vlan_ethhdr *)skb_mac_header(skb); proto = veth->h_vlan_encapsulated_proto; break; diff --git a/net/netfilter/nf_flow_table_ip.c b/net/netfilter/nf_flow_table_ip.c index c2c005234dcd38..98edcaa37b38d4 100644 --- a/net/netfilter/nf_flow_table_ip.c +++ b/net/netfilter/nf_flow_table_ip.c @@ -281,6 +281,9 @@ static bool nf_flow_skb_encap_protocol(struct sk_buff *skb, __be16 proto, switch (skb->protocol) { case htons(ETH_P_8021Q): + if (!pskb_may_pull(skb, skb_mac_offset(skb) + sizeof(*veth))) + return false; + veth = (struct vlan_ethhdr *)skb_mac_header(skb); if (veth->h_vlan_encapsulated_proto == proto) { *offset += VLAN_HLEN;