From a10fa0b489d627911895b64c6530636748dd7911 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Thu, 11 May 2023 07:35:34 +0200 Subject: [PATCH] netfilter: flowtable: split IPv4 datapath in helper functions Add context structure and helper functions to look up for a matching IPv4 entry in the flowtable and to forward packets. No functional changes are intended. Signed-off-by: Pablo Neira Ayuso Signed-off-by: Florian Westphal --- net/netfilter/nf_flow_table_ip.c | 119 +++++++++++++++++++++++++-------------- 1 file changed, 77 insertions(+), 42 deletions(-) diff --git a/net/netfilter/nf_flow_table_ip.c b/net/netfilter/nf_flow_table_ip.c index 19efba1..3fb4761 100644 --- a/net/netfilter/nf_flow_table_ip.c +++ b/net/netfilter/nf_flow_table_ip.c @@ -163,38 +163,43 @@ static void nf_flow_tuple_encap(struct sk_buff *skb, } } -static int nf_flow_tuple_ip(struct sk_buff *skb, const struct net_device *dev, - struct flow_offload_tuple *tuple, u32 *hdrsize, - u32 offset) +struct nf_flowtable_ctx { + const struct net_device *in; + u32 offset; + u32 hdrsize; +}; + +static int nf_flow_tuple_ip(struct nf_flowtable_ctx *ctx, struct sk_buff *skb, + struct flow_offload_tuple *tuple) { struct flow_ports *ports; unsigned int thoff; struct iphdr *iph; u8 ipproto; - if (!pskb_may_pull(skb, sizeof(*iph) + offset)) + if (!pskb_may_pull(skb, sizeof(*iph) + ctx->offset)) return -1; - iph = (struct iphdr *)(skb_network_header(skb) + offset); + iph = (struct iphdr *)(skb_network_header(skb) + ctx->offset); thoff = (iph->ihl * 4); if (ip_is_fragment(iph) || unlikely(ip_has_options(thoff))) return -1; - thoff += offset; + thoff += ctx->offset; ipproto = iph->protocol; switch (ipproto) { case IPPROTO_TCP: - *hdrsize = sizeof(struct tcphdr); + ctx->hdrsize = sizeof(struct tcphdr); break; case IPPROTO_UDP: - *hdrsize = sizeof(struct udphdr); + ctx->hdrsize = sizeof(struct udphdr); break; #ifdef CONFIG_NF_CT_PROTO_GRE case IPPROTO_GRE: - *hdrsize = sizeof(struct gre_base_hdr); + ctx->hdrsize = sizeof(struct gre_base_hdr); break; #endif default: @@ -204,7 +209,7 @@ static int nf_flow_tuple_ip(struct sk_buff *skb, const struct net_device *dev, if (iph->ttl <= 1) return -1; - if (!pskb_may_pull(skb, thoff + *hdrsize)) + if (!pskb_may_pull(skb, thoff + ctx->hdrsize)) return -1; switch (ipproto) { @@ -224,13 +229,13 @@ static int nf_flow_tuple_ip(struct sk_buff *skb, const struct net_device *dev, } } - iph = (struct iphdr *)(skb_network_header(skb) + offset); + iph = (struct iphdr *)(skb_network_header(skb) + ctx->offset); tuple->src_v4.s_addr = iph->saddr; tuple->dst_v4.s_addr = iph->daddr; tuple->l3proto = AF_INET; tuple->l4proto = ipproto; - tuple->iifidx = dev->ifindex; + tuple->iifidx = ctx->in->ifindex; nf_flow_tuple_encap(skb, tuple); return 0; @@ -336,58 +341,56 @@ static unsigned int nf_flow_queue_xmit(struct net *net, struct sk_buff *skb, return NF_STOLEN; } -unsigned int -nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb, - const struct nf_hook_state *state) +static struct flow_offload_tuple_rhash * +nf_flow_offload_lookup(struct nf_flowtable_ctx *ctx, + struct nf_flowtable *flow_table, struct sk_buff *skb) { - struct flow_offload_tuple_rhash *tuplehash; - struct nf_flowtable *flow_table = priv; struct flow_offload_tuple tuple = {}; - enum flow_offload_tuple_dir dir; - struct flow_offload *flow; - struct net_device *outdev; - u32 hdrsize, offset = 0; - unsigned int thoff, mtu; - struct rtable *rt; - struct iphdr *iph; - __be32 nexthop; - int ret; if (skb->protocol != htons(ETH_P_IP) && - !nf_flow_skb_encap_protocol(skb, htons(ETH_P_IP), &offset)) - return NF_ACCEPT; + !nf_flow_skb_encap_protocol(skb, htons(ETH_P_IP), &ctx->offset)) + return NULL; - if (nf_flow_tuple_ip(skb, state->in, &tuple, &hdrsize, offset) < 0) - return NF_ACCEPT; + if (nf_flow_tuple_ip(ctx, skb, &tuple) < 0) + return NULL; - tuplehash = flow_offload_lookup(flow_table, &tuple); - if (tuplehash == NULL) - return NF_ACCEPT; + return flow_offload_lookup(flow_table, &tuple); +} + +static int nf_flow_offload_forward(struct nf_flowtable_ctx *ctx, + struct nf_flowtable *flow_table, + struct flow_offload_tuple_rhash *tuplehash, + struct sk_buff *skb) +{ + enum flow_offload_tuple_dir dir; + struct flow_offload *flow; + unsigned int thoff, mtu; + struct iphdr *iph; dir = tuplehash->tuple.dir; flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]); - mtu = flow->tuplehash[dir].tuple.mtu + offset; + mtu = flow->tuplehash[dir].tuple.mtu + ctx->offset; if (unlikely(nf_flow_exceeds_mtu(skb, mtu))) - return NF_ACCEPT; + return 0; - iph = (struct iphdr *)(skb_network_header(skb) + offset); - thoff = (iph->ihl * 4) + offset; + iph = (struct iphdr *)(skb_network_header(skb) + ctx->offset); + thoff = (iph->ihl * 4) + ctx->offset; if (nf_flow_state_check(flow, iph->protocol, skb, thoff)) - return NF_ACCEPT; + return 0; if (!nf_flow_dst_check(&tuplehash->tuple)) { flow_offload_teardown(flow); - return NF_ACCEPT; + return 0; } - if (skb_try_make_writable(skb, thoff + hdrsize)) - return NF_DROP; + if (skb_try_make_writable(skb, thoff + ctx->hdrsize)) + return -1; flow_offload_refresh(flow_table, flow); nf_flow_encap_pop(skb, tuplehash); - thoff -= offset; + thoff -= ctx->offset; iph = ip_hdr(skb); nf_flow_nat_ip(flow, skb, thoff, dir, iph); @@ -398,6 +401,35 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb, if (flow_table->flags & NF_FLOWTABLE_COUNTER) nf_ct_acct_update(flow->ct, tuplehash->tuple.dir, skb->len); + return 1; +} + +unsigned int +nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb, + const struct nf_hook_state *state) +{ + struct flow_offload_tuple_rhash *tuplehash; + struct nf_flowtable *flow_table = priv; + enum flow_offload_tuple_dir dir; + struct nf_flowtable_ctx ctx = { + .in = state->in, + }; + struct flow_offload *flow; + struct net_device *outdev; + struct rtable *rt; + __be32 nexthop; + int ret; + + tuplehash = nf_flow_offload_lookup(&ctx, flow_table, skb); + if (!tuplehash) + return NF_ACCEPT; + + ret = nf_flow_offload_forward(&ctx, flow_table, tuplehash, skb); + if (ret < 0) + return NF_DROP; + else if (ret == 0) + return NF_ACCEPT; + if (unlikely(tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM)) { rt = (struct rtable *)tuplehash->tuple.dst_cache; memset(skb->cb, 0, sizeof(struct inet_skb_parm)); @@ -406,6 +438,9 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb, return nf_flow_xmit_xfrm(skb, state, &rt->dst); } + dir = tuplehash->tuple.dir; + flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]); + switch (tuplehash->tuple.xmit_type) { case FLOW_OFFLOAD_XMIT_NEIGH: rt = (struct rtable *)tuplehash->tuple.dst_cache; -- 2.7.4