From c7aab4f17021b636a0ee75bcf28e06fb7c94ab48 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Mon, 25 Apr 2022 11:47:11 +0200 Subject: netfilter: nf_conntrack_tcp: re-init for syn packets only Jaco Kroon reported tcp problems that Eric Dumazet and Neal Cardwell pinpointed to nf_conntrack tcp_in_window() bug. tcp trace shows following sequence: I > R Flags [S], seq 3451342529, win 62580, options [.. tfo [|tcp]> R > I Flags [S.], seq 2699962254, ack 3451342530, win 65535, options [..] R > I Flags [P.], seq 1:89, ack 1, [..] Note 3rd ACK is from responder to initiator so following branch is taken: } else if (((state->state == TCP_CONNTRACK_SYN_SENT && dir == IP_CT_DIR_ORIGINAL) || (state->state == TCP_CONNTRACK_SYN_RECV && dir == IP_CT_DIR_REPLY)) && after(end, sender->td_end)) { ... because state == TCP_CONNTRACK_SYN_RECV and dir is REPLY. This causes the scaling factor to be reset to 0: window scale option is only present in syn(ack) packets. This in turn makes nf_conntrack mark valid packets as out-of-window. This was always broken, it exists even in original commit where window tracking was added to ip_conntrack (nf_conntrack predecessor) in 2.6.9-rc1 kernel. Restrict to 'tcph->syn', just like the 3rd condtional added in commit 82b72cb94666 ("netfilter: conntrack: re-init state for retransmitted syn-ack"). Upon closer look, those conditionals/branches can be merged: Because earlier checks prevent syn-ack from showing up in original direction, the 'dir' checks in the conditional quoted above are redundant, remove them. Return early for pure syn retransmitted in reply direction (simultaneous open). Fixes: 9fb9cbb1082d ("[NETFILTER]: Add nf_conntrack subsystem.") Reported-by: Jaco Kroon Signed-off-by: Florian Westphal Acked-by: Jozsef Kadlecsik Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_proto_tcp.c | 21 ++++++--------------- 1 file changed, 6 insertions(+), 15 deletions(-) diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c index 8ec55cd72572..204a5cdff5b1 100644 --- a/net/netfilter/nf_conntrack_proto_tcp.c +++ b/net/netfilter/nf_conntrack_proto_tcp.c @@ -556,24 +556,14 @@ static bool tcp_in_window(struct nf_conn *ct, } } - } else if (((state->state == TCP_CONNTRACK_SYN_SENT - && dir == IP_CT_DIR_ORIGINAL) - || (state->state == TCP_CONNTRACK_SYN_RECV - && dir == IP_CT_DIR_REPLY)) - && after(end, sender->td_end)) { + } else if (tcph->syn && + after(end, sender->td_end) && + (state->state == TCP_CONNTRACK_SYN_SENT || + state->state == TCP_CONNTRACK_SYN_RECV)) { /* * RFC 793: "if a TCP is reinitialized ... then it need * not wait at all; it must only be sure to use sequence * numbers larger than those recently used." - */ - sender->td_end = - sender->td_maxend = end; - sender->td_maxwin = (win == 0 ? 1 : win); - - tcp_options(skb, dataoff, tcph, sender); - } else if (tcph->syn && dir == IP_CT_DIR_REPLY && - state->state == TCP_CONNTRACK_SYN_SENT) { - /* Retransmitted syn-ack, or syn (simultaneous open). * * Re-init state for this direction, just like for the first * syn(-ack) reply, it might differ in seq, ack or tcp options. @@ -581,7 +571,8 @@ static bool tcp_in_window(struct nf_conn *ct, tcp_init_sender(sender, receiver, skb, dataoff, tcph, end, win); - if (!tcph->ack) + + if (dir == IP_CT_DIR_REPLY && !tcph->ack) return true; } -- cgit v1.2.3 From 626873c446f7559d5af8b48cefad903ffd85cf4e Mon Sep 17 00:00:00 2001 From: Volodymyr Mytnyk Date: Wed, 27 Apr 2022 14:09:00 +0300 Subject: netfilter: conntrack: fix udp offload timeout sysctl `nf_flowtable_udp_timeout` sysctl option is available only if CONFIG_NFT_FLOW_OFFLOAD enabled. But infra for this flow offload UDP timeout was added under CONFIG_NF_FLOW_TABLE config option. So, if you have CONFIG_NFT_FLOW_OFFLOAD disabled and CONFIG_NF_FLOW_TABLE enabled, the `nf_flowtable_udp_timeout` is not present in sysfs. Please note, that TCP flow offload timeout sysctl option is present even CONFIG_NFT_FLOW_OFFLOAD is disabled. I suppose it was a typo in commit that adds UDP flow offload timeout and CONFIG_NF_FLOW_TABLE should be used instead. Fixes: 975c57504da1 ("netfilter: conntrack: Introduce udp offload timeout configuration") Signed-off-by: Volodymyr Mytnyk Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_standalone.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c index 3e1afd10a9b6..55aa55b252b2 100644 --- a/net/netfilter/nf_conntrack_standalone.c +++ b/net/netfilter/nf_conntrack_standalone.c @@ -823,7 +823,7 @@ static struct ctl_table nf_ct_sysctl_table[] = { .mode = 0644, .proc_handler = proc_dointvec_jiffies, }, -#if IS_ENABLED(CONFIG_NFT_FLOW_OFFLOAD) +#if IS_ENABLED(CONFIG_NF_FLOW_TABLE) [NF_SYSCTL_CT_PROTO_TIMEOUT_UDP_OFFLOAD] = { .procname = "nf_flowtable_udp_timeout", .maxlen = sizeof(unsigned int), -- cgit v1.2.3 From 743b83f15d4069ea57c3e40996bf4a1077e0cdc1 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Thu, 28 Apr 2022 09:39:21 +0200 Subject: netfilter: nft_socket: only do sk lookups when indev is available Check if the incoming interface is available and NFT_BREAK in case neither skb->sk nor input device are set. Because nf_sk_lookup_slow*() assume packet headers are in the 'in' direction, use in postrouting is not going to yield a meaningful result. Same is true for the forward chain, so restrict the use to prerouting, input and output. Use in output work if a socket is already attached to the skb. Fixes: 554ced0a6e29 ("netfilter: nf_tables: add support for native socket matching") Reported-and-tested-by: Topi Miettinen Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nft_socket.c | 52 +++++++++++++++++++++++++++++++++------------- 1 file changed, 38 insertions(+), 14 deletions(-) diff --git a/net/netfilter/nft_socket.c b/net/netfilter/nft_socket.c index 6d9e8e0a3a7d..05ae5a338b6f 100644 --- a/net/netfilter/nft_socket.c +++ b/net/netfilter/nft_socket.c @@ -54,6 +54,32 @@ nft_sock_get_eval_cgroupv2(u32 *dest, struct sock *sk, const struct nft_pktinfo } #endif +static struct sock *nft_socket_do_lookup(const struct nft_pktinfo *pkt) +{ + const struct net_device *indev = nft_in(pkt); + const struct sk_buff *skb = pkt->skb; + struct sock *sk = NULL; + + if (!indev) + return NULL; + + switch (nft_pf(pkt)) { + case NFPROTO_IPV4: + sk = nf_sk_lookup_slow_v4(nft_net(pkt), skb, indev); + break; +#if IS_ENABLED(CONFIG_NF_TABLES_IPV6) + case NFPROTO_IPV6: + sk = nf_sk_lookup_slow_v6(nft_net(pkt), skb, indev); + break; +#endif + default: + WARN_ON_ONCE(1); + break; + } + + return sk; +} + static void nft_socket_eval(const struct nft_expr *expr, struct nft_regs *regs, const struct nft_pktinfo *pkt) @@ -67,20 +93,7 @@ static void nft_socket_eval(const struct nft_expr *expr, sk = NULL; if (!sk) - switch(nft_pf(pkt)) { - case NFPROTO_IPV4: - sk = nf_sk_lookup_slow_v4(nft_net(pkt), skb, nft_in(pkt)); - break; -#if IS_ENABLED(CONFIG_NF_TABLES_IPV6) - case NFPROTO_IPV6: - sk = nf_sk_lookup_slow_v6(nft_net(pkt), skb, nft_in(pkt)); - break; -#endif - default: - WARN_ON_ONCE(1); - regs->verdict.code = NFT_BREAK; - return; - } + sk = nft_socket_do_lookup(pkt); if (!sk) { regs->verdict.code = NFT_BREAK; @@ -224,6 +237,16 @@ static bool nft_socket_reduce(struct nft_regs_track *track, return nft_expr_reduce_bitwise(track, expr); } +static int nft_socket_validate(const struct nft_ctx *ctx, + const struct nft_expr *expr, + const struct nft_data **data) +{ + return nft_chain_validate_hooks(ctx->chain, + (1 << NF_INET_PRE_ROUTING) | + (1 << NF_INET_LOCAL_IN) | + (1 << NF_INET_LOCAL_OUT)); +} + static struct nft_expr_type nft_socket_type; static const struct nft_expr_ops nft_socket_ops = { .type = &nft_socket_type, @@ -231,6 +254,7 @@ static const struct nft_expr_ops nft_socket_ops = { .eval = nft_socket_eval, .init = nft_socket_init, .dump = nft_socket_dump, + .validate = nft_socket_validate, .reduce = nft_socket_reduce, }; -- cgit v1.2.3