1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * Stateless NAT actions |
4 | * |
5 | * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au> |
6 | */ |
7 | |
8 | #include <linux/errno.h> |
9 | #include <linux/init.h> |
10 | #include <linux/kernel.h> |
11 | #include <linux/module.h> |
12 | #include <linux/netfilter.h> |
13 | #include <linux/rtnetlink.h> |
14 | #include <linux/skbuff.h> |
15 | #include <linux/slab.h> |
16 | #include <linux/spinlock.h> |
17 | #include <linux/string.h> |
18 | #include <linux/tc_act/tc_nat.h> |
19 | #include <net/act_api.h> |
20 | #include <net/pkt_cls.h> |
21 | #include <net/icmp.h> |
22 | #include <net/ip.h> |
23 | #include <net/netlink.h> |
24 | #include <net/tc_act/tc_nat.h> |
25 | #include <net/tcp.h> |
26 | #include <net/udp.h> |
27 | #include <net/tc_wrapper.h> |
28 | |
29 | static struct tc_action_ops act_nat_ops; |
30 | |
31 | static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = { |
32 | [TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) }, |
33 | }; |
34 | |
35 | static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est, |
36 | struct tc_action **a, struct tcf_proto *tp, |
37 | u32 flags, struct netlink_ext_ack *extack) |
38 | { |
39 | struct tc_action_net *tn = net_generic(net, id: act_nat_ops.net_id); |
40 | bool bind = flags & TCA_ACT_FLAGS_BIND; |
41 | struct tcf_nat_parms *nparm, *oparm; |
42 | struct nlattr *tb[TCA_NAT_MAX + 1]; |
43 | struct tcf_chain *goto_ch = NULL; |
44 | struct tc_nat *parm; |
45 | int ret = 0, err; |
46 | struct tcf_nat *p; |
47 | u32 index; |
48 | |
49 | if (nla == NULL) |
50 | return -EINVAL; |
51 | |
52 | err = nla_parse_nested_deprecated(tb, TCA_NAT_MAX, nla, policy: nat_policy, |
53 | NULL); |
54 | if (err < 0) |
55 | return err; |
56 | |
57 | if (tb[TCA_NAT_PARMS] == NULL) |
58 | return -EINVAL; |
59 | parm = nla_data(nla: tb[TCA_NAT_PARMS]); |
60 | index = parm->index; |
61 | err = tcf_idr_check_alloc(tn, index: &index, a, bind); |
62 | if (!err) { |
63 | ret = tcf_idr_create_from_flags(tn, index, est, a, ops: &act_nat_ops, |
64 | bind, flags); |
65 | if (ret) { |
66 | tcf_idr_cleanup(tn, index); |
67 | return ret; |
68 | } |
69 | ret = ACT_P_CREATED; |
70 | } else if (err > 0) { |
71 | if (bind) |
72 | return 0; |
73 | if (!(flags & TCA_ACT_FLAGS_REPLACE)) { |
74 | tcf_idr_release(a: *a, bind); |
75 | return -EEXIST; |
76 | } |
77 | } else { |
78 | return err; |
79 | } |
80 | err = tcf_action_check_ctrlact(action: parm->action, tp, handle: &goto_ch, newchain: extack); |
81 | if (err < 0) |
82 | goto release_idr; |
83 | |
84 | nparm = kzalloc(size: sizeof(*nparm), GFP_KERNEL); |
85 | if (!nparm) { |
86 | err = -ENOMEM; |
87 | goto release_idr; |
88 | } |
89 | |
90 | nparm->old_addr = parm->old_addr; |
91 | nparm->new_addr = parm->new_addr; |
92 | nparm->mask = parm->mask; |
93 | nparm->flags = parm->flags; |
94 | |
95 | p = to_tcf_nat(*a); |
96 | |
97 | spin_lock_bh(lock: &p->tcf_lock); |
98 | goto_ch = tcf_action_set_ctrlact(a: *a, action: parm->action, newchain: goto_ch); |
99 | oparm = rcu_replace_pointer(p->parms, nparm, lockdep_is_held(&p->tcf_lock)); |
100 | spin_unlock_bh(lock: &p->tcf_lock); |
101 | |
102 | if (goto_ch) |
103 | tcf_chain_put_by_act(chain: goto_ch); |
104 | |
105 | if (oparm) |
106 | kfree_rcu(oparm, rcu); |
107 | |
108 | return ret; |
109 | release_idr: |
110 | tcf_idr_release(a: *a, bind); |
111 | return err; |
112 | } |
113 | |
114 | TC_INDIRECT_SCOPE int tcf_nat_act(struct sk_buff *skb, |
115 | const struct tc_action *a, |
116 | struct tcf_result *res) |
117 | { |
118 | struct tcf_nat *p = to_tcf_nat(a); |
119 | struct tcf_nat_parms *parms; |
120 | struct iphdr *iph; |
121 | __be32 old_addr; |
122 | __be32 new_addr; |
123 | __be32 mask; |
124 | __be32 addr; |
125 | int egress; |
126 | int action; |
127 | int ihl; |
128 | int noff; |
129 | |
130 | tcf_lastuse_update(tm: &p->tcf_tm); |
131 | tcf_action_update_bstats(a: &p->common, skb); |
132 | |
133 | action = READ_ONCE(p->tcf_action); |
134 | |
135 | parms = rcu_dereference_bh(p->parms); |
136 | old_addr = parms->old_addr; |
137 | new_addr = parms->new_addr; |
138 | mask = parms->mask; |
139 | egress = parms->flags & TCA_NAT_FLAG_EGRESS; |
140 | |
141 | if (unlikely(action == TC_ACT_SHOT)) |
142 | goto drop; |
143 | |
144 | noff = skb_network_offset(skb); |
145 | if (!pskb_may_pull(skb, len: sizeof(*iph) + noff)) |
146 | goto drop; |
147 | |
148 | iph = ip_hdr(skb); |
149 | |
150 | if (egress) |
151 | addr = iph->saddr; |
152 | else |
153 | addr = iph->daddr; |
154 | |
155 | if (!((old_addr ^ addr) & mask)) { |
156 | if (skb_try_make_writable(skb, write_len: sizeof(*iph) + noff)) |
157 | goto drop; |
158 | |
159 | new_addr &= mask; |
160 | new_addr |= addr & ~mask; |
161 | |
162 | /* Rewrite IP header */ |
163 | iph = ip_hdr(skb); |
164 | if (egress) |
165 | iph->saddr = new_addr; |
166 | else |
167 | iph->daddr = new_addr; |
168 | |
169 | csum_replace4(sum: &iph->check, from: addr, to: new_addr); |
170 | } else if ((iph->frag_off & htons(IP_OFFSET)) || |
171 | iph->protocol != IPPROTO_ICMP) { |
172 | goto out; |
173 | } |
174 | |
175 | ihl = iph->ihl * 4; |
176 | |
177 | /* It would be nice to share code with stateful NAT. */ |
178 | switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) { |
179 | case IPPROTO_TCP: |
180 | { |
181 | struct tcphdr *tcph; |
182 | |
183 | if (!pskb_may_pull(skb, len: ihl + sizeof(*tcph) + noff) || |
184 | skb_try_make_writable(skb, write_len: ihl + sizeof(*tcph) + noff)) |
185 | goto drop; |
186 | |
187 | tcph = (void *)(skb_network_header(skb) + ihl); |
188 | inet_proto_csum_replace4(sum: &tcph->check, skb, from: addr, to: new_addr, |
189 | pseudohdr: true); |
190 | break; |
191 | } |
192 | case IPPROTO_UDP: |
193 | { |
194 | struct udphdr *udph; |
195 | |
196 | if (!pskb_may_pull(skb, len: ihl + sizeof(*udph) + noff) || |
197 | skb_try_make_writable(skb, write_len: ihl + sizeof(*udph) + noff)) |
198 | goto drop; |
199 | |
200 | udph = (void *)(skb_network_header(skb) + ihl); |
201 | if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) { |
202 | inet_proto_csum_replace4(sum: &udph->check, skb, from: addr, |
203 | to: new_addr, pseudohdr: true); |
204 | if (!udph->check) |
205 | udph->check = CSUM_MANGLED_0; |
206 | } |
207 | break; |
208 | } |
209 | case IPPROTO_ICMP: |
210 | { |
211 | struct icmphdr *icmph; |
212 | |
213 | if (!pskb_may_pull(skb, len: ihl + sizeof(*icmph) + noff)) |
214 | goto drop; |
215 | |
216 | icmph = (void *)(skb_network_header(skb) + ihl); |
217 | |
218 | if (!icmp_is_err(type: icmph->type)) |
219 | break; |
220 | |
221 | if (!pskb_may_pull(skb, len: ihl + sizeof(*icmph) + sizeof(*iph) + |
222 | noff)) |
223 | goto drop; |
224 | |
225 | icmph = (void *)(skb_network_header(skb) + ihl); |
226 | iph = (void *)(icmph + 1); |
227 | if (egress) |
228 | addr = iph->daddr; |
229 | else |
230 | addr = iph->saddr; |
231 | |
232 | if ((old_addr ^ addr) & mask) |
233 | break; |
234 | |
235 | if (skb_try_make_writable(skb, write_len: ihl + sizeof(*icmph) + |
236 | sizeof(*iph) + noff)) |
237 | goto drop; |
238 | |
239 | icmph = (void *)(skb_network_header(skb) + ihl); |
240 | iph = (void *)(icmph + 1); |
241 | |
242 | new_addr &= mask; |
243 | new_addr |= addr & ~mask; |
244 | |
245 | /* XXX Fix up the inner checksums. */ |
246 | if (egress) |
247 | iph->daddr = new_addr; |
248 | else |
249 | iph->saddr = new_addr; |
250 | |
251 | inet_proto_csum_replace4(sum: &icmph->checksum, skb, from: addr, to: new_addr, |
252 | pseudohdr: false); |
253 | break; |
254 | } |
255 | default: |
256 | break; |
257 | } |
258 | |
259 | out: |
260 | return action; |
261 | |
262 | drop: |
263 | tcf_action_inc_drop_qstats(a: &p->common); |
264 | return TC_ACT_SHOT; |
265 | } |
266 | |
267 | static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a, |
268 | int bind, int ref) |
269 | { |
270 | unsigned char *b = skb_tail_pointer(skb); |
271 | struct tcf_nat *p = to_tcf_nat(a); |
272 | struct tc_nat opt = { |
273 | .index = p->tcf_index, |
274 | .refcnt = refcount_read(r: &p->tcf_refcnt) - ref, |
275 | .bindcnt = atomic_read(v: &p->tcf_bindcnt) - bind, |
276 | }; |
277 | struct tcf_nat_parms *parms; |
278 | struct tcf_t t; |
279 | |
280 | spin_lock_bh(lock: &p->tcf_lock); |
281 | |
282 | opt.action = p->tcf_action; |
283 | |
284 | parms = rcu_dereference_protected(p->parms, lockdep_is_held(&p->tcf_lock)); |
285 | |
286 | opt.old_addr = parms->old_addr; |
287 | opt.new_addr = parms->new_addr; |
288 | opt.mask = parms->mask; |
289 | opt.flags = parms->flags; |
290 | |
291 | if (nla_put(skb, attrtype: TCA_NAT_PARMS, attrlen: sizeof(opt), data: &opt)) |
292 | goto nla_put_failure; |
293 | |
294 | tcf_tm_dump(dtm: &t, stm: &p->tcf_tm); |
295 | if (nla_put_64bit(skb, attrtype: TCA_NAT_TM, attrlen: sizeof(t), data: &t, padattr: TCA_NAT_PAD)) |
296 | goto nla_put_failure; |
297 | spin_unlock_bh(lock: &p->tcf_lock); |
298 | |
299 | return skb->len; |
300 | |
301 | nla_put_failure: |
302 | spin_unlock_bh(lock: &p->tcf_lock); |
303 | nlmsg_trim(skb, mark: b); |
304 | return -1; |
305 | } |
306 | |
307 | static void tcf_nat_cleanup(struct tc_action *a) |
308 | { |
309 | struct tcf_nat *p = to_tcf_nat(a); |
310 | struct tcf_nat_parms *parms; |
311 | |
312 | parms = rcu_dereference_protected(p->parms, 1); |
313 | if (parms) |
314 | kfree_rcu(parms, rcu); |
315 | } |
316 | |
317 | static struct tc_action_ops act_nat_ops = { |
318 | .kind = "nat" , |
319 | .id = TCA_ID_NAT, |
320 | .owner = THIS_MODULE, |
321 | .act = tcf_nat_act, |
322 | .dump = tcf_nat_dump, |
323 | .init = tcf_nat_init, |
324 | .cleanup = tcf_nat_cleanup, |
325 | .size = sizeof(struct tcf_nat), |
326 | }; |
327 | |
328 | static __net_init int nat_init_net(struct net *net) |
329 | { |
330 | struct tc_action_net *tn = net_generic(net, id: act_nat_ops.net_id); |
331 | |
332 | return tc_action_net_init(net, tn, ops: &act_nat_ops); |
333 | } |
334 | |
335 | static void __net_exit nat_exit_net(struct list_head *net_list) |
336 | { |
337 | tc_action_net_exit(net_list, id: act_nat_ops.net_id); |
338 | } |
339 | |
340 | static struct pernet_operations nat_net_ops = { |
341 | .init = nat_init_net, |
342 | .exit_batch = nat_exit_net, |
343 | .id = &act_nat_ops.net_id, |
344 | .size = sizeof(struct tc_action_net), |
345 | }; |
346 | |
347 | MODULE_DESCRIPTION("Stateless NAT actions" ); |
348 | MODULE_LICENSE("GPL" ); |
349 | |
350 | static int __init nat_init_module(void) |
351 | { |
352 | return tcf_register_action(a: &act_nat_ops, ops: &nat_net_ops); |
353 | } |
354 | |
355 | static void __exit nat_cleanup_module(void) |
356 | { |
357 | tcf_unregister_action(a: &act_nat_ops, ops: &nat_net_ops); |
358 | } |
359 | |
360 | module_init(nat_init_module); |
361 | module_exit(nat_cleanup_module); |
362 | |