ramips: add support for mqmaker witi 512mb version
[openwrt/openwrt.git] / target / linux / generic / backport-4.14 / 323-netfilter-flow-table-support-for-IPv4.patch
1 From: Pablo Neira Ayuso <pablo@netfilter.org>
2 Date: Sun, 7 Jan 2018 01:04:15 +0100
3 Subject: [PATCH] netfilter: flow table support for IPv4
4
5 This patch adds the IPv4 flow table type, that implements the datapath
6 flow table to forward IPv4 traffic. Rationale is:
7
8 1) Look up for the packet in the flow table, from the ingress hook.
9 2) If there's a hit, decrement ttl and pass it on to the neighbour layer
10 for transmission.
11 3) If there's a miss, packet is passed up to the classic forwarding
12 path.
13
14 This patch also supports layer 3 source and destination NAT.
15
16 Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
17 ---
18 create mode 100644 net/ipv4/netfilter/nf_flow_table_ipv4.c
19
20 --- a/net/ipv4/netfilter/Kconfig
21 +++ b/net/ipv4/netfilter/Kconfig
22 @@ -77,6 +77,14 @@ config NF_TABLES_ARP
23
24 endif # NF_TABLES
25
26 +config NF_FLOW_TABLE_IPV4
27 + select NF_FLOW_TABLE
28 + tristate "Netfilter flow table IPv4 module"
29 + help
30 + This option adds the flow table IPv4 support.
31 +
32 + To compile it as a module, choose M here.
33 +
34 config NF_DUP_IPV4
35 tristate "Netfilter IPv4 packet duplication to alternate destination"
36 depends on !NF_CONNTRACK || NF_CONNTRACK
37 --- a/net/ipv4/netfilter/Makefile
38 +++ b/net/ipv4/netfilter/Makefile
39 @@ -43,6 +43,9 @@ obj-$(CONFIG_NFT_REDIR_IPV4) += nft_redi
40 obj-$(CONFIG_NFT_DUP_IPV4) += nft_dup_ipv4.o
41 obj-$(CONFIG_NF_TABLES_ARP) += nf_tables_arp.o
42
43 +# flow table support
44 +obj-$(CONFIG_NF_FLOW_TABLE_IPV4) += nf_flow_table_ipv4.o
45 +
46 # generic IP tables
47 obj-$(CONFIG_IP_NF_IPTABLES) += ip_tables.o
48
49 --- /dev/null
50 +++ b/net/ipv4/netfilter/nf_flow_table_ipv4.c
51 @@ -0,0 +1,283 @@
52 +#include <linux/kernel.h>
53 +#include <linux/init.h>
54 +#include <linux/module.h>
55 +#include <linux/netfilter.h>
56 +#include <linux/rhashtable.h>
57 +#include <linux/ip.h>
58 +#include <linux/netdevice.h>
59 +#include <net/ip.h>
60 +#include <net/neighbour.h>
61 +#include <net/netfilter/nf_flow_table.h>
62 +#include <net/netfilter/nf_tables.h>
63 +/* For layer 4 checksum field offset. */
64 +#include <linux/tcp.h>
65 +#include <linux/udp.h>
66 +
67 +static int nf_flow_nat_ip_tcp(struct sk_buff *skb, unsigned int thoff,
68 + __be32 addr, __be32 new_addr)
69 +{
70 + struct tcphdr *tcph;
71 +
72 + if (!pskb_may_pull(skb, thoff + sizeof(*tcph)) ||
73 + skb_try_make_writable(skb, thoff + sizeof(*tcph)))
74 + return -1;
75 +
76 + tcph = (void *)(skb_network_header(skb) + thoff);
77 + inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr, true);
78 +
79 + return 0;
80 +}
81 +
82 +static int nf_flow_nat_ip_udp(struct sk_buff *skb, unsigned int thoff,
83 + __be32 addr, __be32 new_addr)
84 +{
85 + struct udphdr *udph;
86 +
87 + if (!pskb_may_pull(skb, thoff + sizeof(*udph)) ||
88 + skb_try_make_writable(skb, thoff + sizeof(*udph)))
89 + return -1;
90 +
91 + udph = (void *)(skb_network_header(skb) + thoff);
92 + if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
93 + inet_proto_csum_replace4(&udph->check, skb, addr,
94 + new_addr, true);
95 + if (!udph->check)
96 + udph->check = CSUM_MANGLED_0;
97 + }
98 +
99 + return 0;
100 +}
101 +
102 +static int nf_flow_nat_ip_l4proto(struct sk_buff *skb, struct iphdr *iph,
103 + unsigned int thoff, __be32 addr,
104 + __be32 new_addr)
105 +{
106 + switch (iph->protocol) {
107 + case IPPROTO_TCP:
108 + if (nf_flow_nat_ip_tcp(skb, thoff, addr, new_addr) < 0)
109 + return NF_DROP;
110 + break;
111 + case IPPROTO_UDP:
112 + if (nf_flow_nat_ip_udp(skb, thoff, addr, new_addr) < 0)
113 + return NF_DROP;
114 + break;
115 + }
116 +
117 + return 0;
118 +}
119 +
120 +static int nf_flow_snat_ip(const struct flow_offload *flow, struct sk_buff *skb,
121 + struct iphdr *iph, unsigned int thoff,
122 + enum flow_offload_tuple_dir dir)
123 +{
124 + __be32 addr, new_addr;
125 +
126 + switch (dir) {
127 + case FLOW_OFFLOAD_DIR_ORIGINAL:
128 + addr = iph->saddr;
129 + new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_v4.s_addr;
130 + iph->saddr = new_addr;
131 + break;
132 + case FLOW_OFFLOAD_DIR_REPLY:
133 + addr = iph->daddr;
134 + new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_v4.s_addr;
135 + iph->daddr = new_addr;
136 + break;
137 + default:
138 + return -1;
139 + }
140 + csum_replace4(&iph->check, addr, new_addr);
141 +
142 + return nf_flow_nat_ip_l4proto(skb, iph, thoff, addr, new_addr);
143 +}
144 +
145 +static int nf_flow_dnat_ip(const struct flow_offload *flow, struct sk_buff *skb,
146 + struct iphdr *iph, unsigned int thoff,
147 + enum flow_offload_tuple_dir dir)
148 +{
149 + __be32 addr, new_addr;
150 +
151 + switch (dir) {
152 + case FLOW_OFFLOAD_DIR_ORIGINAL:
153 + addr = iph->daddr;
154 + new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_v4.s_addr;
155 + iph->daddr = new_addr;
156 + break;
157 + case FLOW_OFFLOAD_DIR_REPLY:
158 + addr = iph->saddr;
159 + new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_v4.s_addr;
160 + iph->saddr = new_addr;
161 + break;
162 + default:
163 + return -1;
164 + }
165 +
166 + return nf_flow_nat_ip_l4proto(skb, iph, thoff, addr, new_addr);
167 +}
168 +
169 +static int nf_flow_nat_ip(const struct flow_offload *flow, struct sk_buff *skb,
170 + enum flow_offload_tuple_dir dir)
171 +{
172 + struct iphdr *iph = ip_hdr(skb);
173 + unsigned int thoff = iph->ihl * 4;
174 +
175 + if (flow->flags & FLOW_OFFLOAD_SNAT &&
176 + (nf_flow_snat_port(flow, skb, thoff, iph->protocol, dir) < 0 ||
177 + nf_flow_snat_ip(flow, skb, iph, thoff, dir) < 0))
178 + return -1;
179 + if (flow->flags & FLOW_OFFLOAD_DNAT &&
180 + (nf_flow_dnat_port(flow, skb, thoff, iph->protocol, dir) < 0 ||
181 + nf_flow_dnat_ip(flow, skb, iph, thoff, dir) < 0))
182 + return -1;
183 +
184 + return 0;
185 +}
186 +
187 +static bool ip_has_options(unsigned int thoff)
188 +{
189 + return thoff != sizeof(struct iphdr);
190 +}
191 +
192 +static int nf_flow_tuple_ip(struct sk_buff *skb, const struct net_device *dev,
193 + struct flow_offload_tuple *tuple)
194 +{
195 + struct flow_ports *ports;
196 + unsigned int thoff;
197 + struct iphdr *iph;
198 +
199 + if (!pskb_may_pull(skb, sizeof(*iph)))
200 + return -1;
201 +
202 + iph = ip_hdr(skb);
203 + thoff = iph->ihl * 4;
204 +
205 + if (ip_is_fragment(iph) ||
206 + unlikely(ip_has_options(thoff)))
207 + return -1;
208 +
209 + if (iph->protocol != IPPROTO_TCP &&
210 + iph->protocol != IPPROTO_UDP)
211 + return -1;
212 +
213 + thoff = iph->ihl * 4;
214 + if (!pskb_may_pull(skb, thoff + sizeof(*ports)))
215 + return -1;
216 +
217 + ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
218 +
219 + tuple->src_v4.s_addr = iph->saddr;
220 + tuple->dst_v4.s_addr = iph->daddr;
221 + tuple->src_port = ports->source;
222 + tuple->dst_port = ports->dest;
223 + tuple->l3proto = AF_INET;
224 + tuple->l4proto = iph->protocol;
225 + tuple->iifidx = dev->ifindex;
226 +
227 + return 0;
228 +}
229 +
230 +/* Based on ip_exceeds_mtu(). */
231 +static bool __nf_flow_exceeds_mtu(const struct sk_buff *skb, unsigned int mtu)
232 +{
233 + if (skb->len <= mtu)
234 + return false;
235 +
236 + if ((ip_hdr(skb)->frag_off & htons(IP_DF)) == 0)
237 + return false;
238 +
239 + if (skb_is_gso(skb) && skb_gso_validate_mtu(skb, mtu))
240 + return false;
241 +
242 + return true;
243 +}
244 +
245 +static bool nf_flow_exceeds_mtu(struct sk_buff *skb, const struct rtable *rt)
246 +{
247 + u32 mtu;
248 +
249 + mtu = ip_dst_mtu_maybe_forward(&rt->dst, true);
250 + if (__nf_flow_exceeds_mtu(skb, mtu))
251 + return true;
252 +
253 + return false;
254 +}
255 +
256 +static unsigned int
257 +nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
258 + const struct nf_hook_state *state)
259 +{
260 + struct flow_offload_tuple_rhash *tuplehash;
261 + struct nf_flowtable *flow_table = priv;
262 + struct flow_offload_tuple tuple = {};
263 + enum flow_offload_tuple_dir dir;
264 + struct flow_offload *flow;
265 + struct net_device *outdev;
266 + const struct rtable *rt;
267 + struct iphdr *iph;
268 + __be32 nexthop;
269 +
270 + if (skb->protocol != htons(ETH_P_IP))
271 + return NF_ACCEPT;
272 +
273 + if (nf_flow_tuple_ip(skb, state->in, &tuple) < 0)
274 + return NF_ACCEPT;
275 +
276 + tuplehash = flow_offload_lookup(flow_table, &tuple);
277 + if (tuplehash == NULL)
278 + return NF_ACCEPT;
279 +
280 + outdev = dev_get_by_index_rcu(state->net, tuplehash->tuple.oifidx);
281 + if (!outdev)
282 + return NF_ACCEPT;
283 +
284 + dir = tuplehash->tuple.dir;
285 + flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
286 +
287 + rt = (const struct rtable *)flow->tuplehash[dir].tuple.dst_cache;
288 + if (unlikely(nf_flow_exceeds_mtu(skb, rt)))
289 + return NF_ACCEPT;
290 +
291 + if (skb_try_make_writable(skb, sizeof(*iph)))
292 + return NF_DROP;
293 +
294 + if (flow->flags & (FLOW_OFFLOAD_SNAT | FLOW_OFFLOAD_DNAT) &&
295 + nf_flow_nat_ip(flow, skb, dir) < 0)
296 + return NF_DROP;
297 +
298 + flow->timeout = (u32)jiffies + NF_FLOW_TIMEOUT;
299 + iph = ip_hdr(skb);
300 + ip_decrease_ttl(iph);
301 +
302 + skb->dev = outdev;
303 + nexthop = rt_nexthop(rt, flow->tuplehash[!dir].tuple.src_v4.s_addr);
304 + neigh_xmit(NEIGH_ARP_TABLE, outdev, &nexthop, skb);
305 +
306 + return NF_STOLEN;
307 +}
308 +
309 +static struct nf_flowtable_type flowtable_ipv4 = {
310 + .family = NFPROTO_IPV4,
311 + .params = &nf_flow_offload_rhash_params,
312 + .gc = nf_flow_offload_work_gc,
313 + .hook = nf_flow_offload_ip_hook,
314 + .owner = THIS_MODULE,
315 +};
316 +
317 +static int __init nf_flow_ipv4_module_init(void)
318 +{
319 + nft_register_flowtable_type(&flowtable_ipv4);
320 +
321 + return 0;
322 +}
323 +
324 +static void __exit nf_flow_ipv4_module_exit(void)
325 +{
326 + nft_unregister_flowtable_type(&flowtable_ipv4);
327 +}
328 +
329 +module_init(nf_flow_ipv4_module_init);
330 +module_exit(nf_flow_ipv4_module_exit);
331 +
332 +MODULE_LICENSE("GPL");
333 +MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
334 +MODULE_ALIAS_NF_FLOWTABLE(AF_INET);