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e2cf17d3 FW |
1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* | |
3 | * Copyright (c) 2021 Red Hat GmbH | |
4 | * | |
5 | * Author: Florian Westphal <fw@strlen.de> | |
6 | */ | |
7 | ||
506a74db | 8 | #include <linux/bpf.h> |
e2cf17d3 | 9 | #include <linux/module.h> |
b6459415 | 10 | #include <linux/kallsyms.h> |
e2cf17d3 FW |
11 | #include <linux/kernel.h> |
12 | #include <linux/types.h> | |
13 | #include <linux/skbuff.h> | |
14 | #include <linux/errno.h> | |
15 | #include <linux/netlink.h> | |
16 | #include <linux/slab.h> | |
17 | ||
18 | #include <linux/netfilter.h> | |
19 | ||
20 | #include <linux/netfilter/nfnetlink.h> | |
21 | #include <linux/netfilter/nfnetlink_hook.h> | |
22 | ||
23 | #include <net/netfilter/nf_tables.h> | |
24 | #include <net/sock.h> | |
25 | ||
26 | static const struct nla_policy nfnl_hook_nla_policy[NFNLA_HOOK_MAX + 1] = { | |
27 | [NFNLA_HOOK_HOOKNUM] = { .type = NLA_U32 }, | |
28 | [NFNLA_HOOK_PRIORITY] = { .type = NLA_U32 }, | |
29 | [NFNLA_HOOK_DEV] = { .type = NLA_STRING, | |
30 | .len = IFNAMSIZ - 1 }, | |
31 | [NFNLA_HOOK_FUNCTION_NAME] = { .type = NLA_NUL_STRING, | |
32 | .len = KSYM_NAME_LEN, }, | |
33 | [NFNLA_HOOK_MODULE_NAME] = { .type = NLA_NUL_STRING, | |
34 | .len = MODULE_NAME_LEN, }, | |
35 | [NFNLA_HOOK_CHAIN_INFO] = { .type = NLA_NESTED, }, | |
36 | }; | |
37 | ||
38 | static int nf_netlink_dump_start_rcu(struct sock *nlsk, struct sk_buff *skb, | |
39 | const struct nlmsghdr *nlh, | |
40 | struct netlink_dump_control *c) | |
41 | { | |
42 | int err; | |
43 | ||
44 | if (!try_module_get(THIS_MODULE)) | |
45 | return -EINVAL; | |
46 | ||
47 | rcu_read_unlock(); | |
48 | err = netlink_dump_start(nlsk, skb, nlh, c); | |
49 | rcu_read_lock(); | |
50 | module_put(THIS_MODULE); | |
51 | ||
52 | return err; | |
53 | } | |
54 | ||
55 | struct nfnl_dump_hook_data { | |
56 | char devname[IFNAMSIZ]; | |
57 | unsigned long headv; | |
58 | u8 hook; | |
59 | }; | |
60 | ||
506a74db FW |
61 | static struct nlattr *nfnl_start_info_type(struct sk_buff *nlskb, enum nfnl_hook_chaintype t) |
62 | { | |
63 | struct nlattr *nest = nla_nest_start(nlskb, NFNLA_HOOK_CHAIN_INFO); | |
64 | int ret; | |
65 | ||
66 | if (!nest) | |
67 | return NULL; | |
68 | ||
69 | ret = nla_put_be32(nlskb, NFNLA_HOOK_INFO_TYPE, htonl(t)); | |
70 | if (ret == 0) | |
71 | return nest; | |
72 | ||
73 | nla_nest_cancel(nlskb, nest); | |
74 | return NULL; | |
75 | } | |
76 | ||
77 | static int nfnl_hook_put_bpf_prog_info(struct sk_buff *nlskb, | |
78 | const struct nfnl_dump_hook_data *ctx, | |
79 | unsigned int seq, | |
80 | const struct bpf_prog *prog) | |
81 | { | |
82 | struct nlattr *nest, *nest2; | |
83 | int ret; | |
84 | ||
85 | if (!IS_ENABLED(CONFIG_NETFILTER_BPF_LINK)) | |
86 | return 0; | |
87 | ||
88 | if (WARN_ON_ONCE(!prog)) | |
89 | return 0; | |
90 | ||
91 | nest = nfnl_start_info_type(nlskb, NFNL_HOOK_TYPE_BPF); | |
92 | if (!nest) | |
93 | return -EMSGSIZE; | |
94 | ||
95 | nest2 = nla_nest_start(nlskb, NFNLA_HOOK_INFO_DESC); | |
96 | if (!nest2) | |
97 | goto cancel_nest; | |
98 | ||
99 | ret = nla_put_be32(nlskb, NFNLA_HOOK_BPF_ID, htonl(prog->aux->id)); | |
100 | if (ret) | |
101 | goto cancel_nest; | |
102 | ||
103 | nla_nest_end(nlskb, nest2); | |
104 | nla_nest_end(nlskb, nest); | |
105 | return 0; | |
106 | ||
107 | cancel_nest: | |
108 | nla_nest_cancel(nlskb, nest); | |
109 | return -EMSGSIZE; | |
110 | } | |
111 | ||
e2cf17d3 FW |
112 | static int nfnl_hook_put_nft_chain_info(struct sk_buff *nlskb, |
113 | const struct nfnl_dump_hook_data *ctx, | |
114 | unsigned int seq, | |
506a74db | 115 | struct nft_chain *chain) |
e2cf17d3 FW |
116 | { |
117 | struct net *net = sock_net(nlskb->sk); | |
118 | struct nlattr *nest, *nest2; | |
e2cf17d3 FW |
119 | int ret = 0; |
120 | ||
e2cf17d3 FW |
121 | if (WARN_ON_ONCE(!chain)) |
122 | return 0; | |
123 | ||
124 | if (!nft_is_active(net, chain)) | |
125 | return 0; | |
126 | ||
506a74db | 127 | nest = nfnl_start_info_type(nlskb, NFNL_HOOK_TYPE_NFTABLES); |
e2cf17d3 FW |
128 | if (!nest) |
129 | return -EMSGSIZE; | |
130 | ||
e2cf17d3 FW |
131 | nest2 = nla_nest_start(nlskb, NFNLA_HOOK_INFO_DESC); |
132 | if (!nest2) | |
133 | goto cancel_nest; | |
134 | ||
a6e57c4a | 135 | ret = nla_put_string(nlskb, NFNLA_CHAIN_TABLE, chain->table->name); |
e2cf17d3 FW |
136 | if (ret) |
137 | goto cancel_nest; | |
138 | ||
a6e57c4a PNA |
139 | ret = nla_put_string(nlskb, NFNLA_CHAIN_NAME, chain->name); |
140 | if (ret) | |
141 | goto cancel_nest; | |
142 | ||
143 | ret = nla_put_u8(nlskb, NFNLA_CHAIN_FAMILY, chain->table->family); | |
e2cf17d3 FW |
144 | if (ret) |
145 | goto cancel_nest; | |
146 | ||
147 | nla_nest_end(nlskb, nest2); | |
148 | nla_nest_end(nlskb, nest); | |
149 | return ret; | |
150 | ||
151 | cancel_nest: | |
152 | nla_nest_cancel(nlskb, nest); | |
153 | return -EMSGSIZE; | |
154 | } | |
155 | ||
156 | static int nfnl_hook_dump_one(struct sk_buff *nlskb, | |
157 | const struct nfnl_dump_hook_data *ctx, | |
158 | const struct nf_hook_ops *ops, | |
69311e7c | 159 | int family, unsigned int seq) |
e2cf17d3 FW |
160 | { |
161 | u16 event = nfnl_msg_type(NFNL_SUBSYS_HOOK, NFNL_MSG_HOOK_GET); | |
162 | unsigned int portid = NETLINK_CB(nlskb).portid; | |
163 | struct nlmsghdr *nlh; | |
164 | int ret = -EMSGSIZE; | |
269fc695 | 165 | u32 hooknum; |
e2cf17d3 FW |
166 | #ifdef CONFIG_KALLSYMS |
167 | char sym[KSYM_SYMBOL_LEN]; | |
168 | char *module_name; | |
169 | #endif | |
170 | nlh = nfnl_msg_put(nlskb, portid, seq, event, | |
69311e7c | 171 | NLM_F_MULTI, family, NFNETLINK_V0, 0); |
e2cf17d3 FW |
172 | if (!nlh) |
173 | goto nla_put_failure; | |
174 | ||
175 | #ifdef CONFIG_KALLSYMS | |
176 | ret = snprintf(sym, sizeof(sym), "%ps", ops->hook); | |
24610ed8 DC |
177 | if (ret >= sizeof(sym)) { |
178 | ret = -EINVAL; | |
e2cf17d3 | 179 | goto nla_put_failure; |
24610ed8 | 180 | } |
e2cf17d3 FW |
181 | |
182 | module_name = strstr(sym, " ["); | |
183 | if (module_name) { | |
184 | char *end; | |
185 | ||
61e0c2bc | 186 | *module_name = '\0'; |
e2cf17d3 FW |
187 | module_name += 2; |
188 | end = strchr(module_name, ']'); | |
189 | if (end) { | |
190 | *end = 0; | |
191 | ||
192 | ret = nla_put_string(nlskb, NFNLA_HOOK_MODULE_NAME, module_name); | |
193 | if (ret) | |
194 | goto nla_put_failure; | |
195 | } | |
196 | } | |
197 | ||
198 | ret = nla_put_string(nlskb, NFNLA_HOOK_FUNCTION_NAME, sym); | |
199 | if (ret) | |
200 | goto nla_put_failure; | |
201 | #endif | |
202 | ||
269fc695 PNA |
203 | if (ops->pf == NFPROTO_INET && ops->hooknum == NF_INET_INGRESS) |
204 | hooknum = NF_NETDEV_INGRESS; | |
205 | else | |
206 | hooknum = ops->hooknum; | |
207 | ||
208 | ret = nla_put_be32(nlskb, NFNLA_HOOK_HOOKNUM, htonl(hooknum)); | |
e2cf17d3 FW |
209 | if (ret) |
210 | goto nla_put_failure; | |
211 | ||
212 | ret = nla_put_be32(nlskb, NFNLA_HOOK_PRIORITY, htonl(ops->priority)); | |
213 | if (ret) | |
214 | goto nla_put_failure; | |
215 | ||
506a74db FW |
216 | switch (ops->hook_ops_type) { |
217 | case NF_HOOK_OP_NF_TABLES: | |
218 | ret = nfnl_hook_put_nft_chain_info(nlskb, ctx, seq, ops->priv); | |
219 | break; | |
220 | case NF_HOOK_OP_BPF: | |
221 | ret = nfnl_hook_put_bpf_prog_info(nlskb, ctx, seq, ops->priv); | |
222 | break; | |
223 | case NF_HOOK_OP_UNDEFINED: | |
224 | break; | |
225 | default: | |
226 | WARN_ON_ONCE(1); | |
227 | break; | |
228 | } | |
229 | ||
e2cf17d3 FW |
230 | if (ret) |
231 | goto nla_put_failure; | |
232 | ||
233 | nlmsg_end(nlskb, nlh); | |
234 | return 0; | |
235 | nla_put_failure: | |
236 | nlmsg_trim(nlskb, nlh); | |
237 | return ret; | |
238 | } | |
239 | ||
240 | static const struct nf_hook_entries * | |
241 | nfnl_hook_entries_head(u8 pf, unsigned int hook, struct net *net, const char *dev) | |
242 | { | |
243 | const struct nf_hook_entries *hook_head = NULL; | |
42df6e1d | 244 | #if defined(CONFIG_NETFILTER_INGRESS) || defined(CONFIG_NETFILTER_EGRESS) |
e2cf17d3 | 245 | struct net_device *netdev; |
217e26bd | 246 | #endif |
e2cf17d3 FW |
247 | |
248 | switch (pf) { | |
249 | case NFPROTO_IPV4: | |
250 | if (hook >= ARRAY_SIZE(net->nf.hooks_ipv4)) | |
251 | return ERR_PTR(-EINVAL); | |
252 | hook_head = rcu_dereference(net->nf.hooks_ipv4[hook]); | |
253 | break; | |
254 | case NFPROTO_IPV6: | |
e2cf17d3 FW |
255 | if (hook >= ARRAY_SIZE(net->nf.hooks_ipv6)) |
256 | return ERR_PTR(-EINVAL); | |
5302560b | 257 | hook_head = rcu_dereference(net->nf.hooks_ipv6[hook]); |
e2cf17d3 FW |
258 | break; |
259 | case NFPROTO_ARP: | |
260 | #ifdef CONFIG_NETFILTER_FAMILY_ARP | |
261 | if (hook >= ARRAY_SIZE(net->nf.hooks_arp)) | |
262 | return ERR_PTR(-EINVAL); | |
263 | hook_head = rcu_dereference(net->nf.hooks_arp[hook]); | |
264 | #endif | |
265 | break; | |
266 | case NFPROTO_BRIDGE: | |
267 | #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE | |
268 | if (hook >= ARRAY_SIZE(net->nf.hooks_bridge)) | |
269 | return ERR_PTR(-EINVAL); | |
270 | hook_head = rcu_dereference(net->nf.hooks_bridge[hook]); | |
271 | #endif | |
272 | break; | |
42df6e1d | 273 | #if defined(CONFIG_NETFILTER_INGRESS) || defined(CONFIG_NETFILTER_EGRESS) |
e2cf17d3 | 274 | case NFPROTO_NETDEV: |
42df6e1d | 275 | if (hook >= NF_NETDEV_NUMHOOKS) |
e2cf17d3 FW |
276 | return ERR_PTR(-EOPNOTSUPP); |
277 | ||
278 | if (!dev) | |
279 | return ERR_PTR(-ENODEV); | |
280 | ||
281 | netdev = dev_get_by_name_rcu(net, dev); | |
282 | if (!netdev) | |
283 | return ERR_PTR(-ENODEV); | |
284 | ||
42df6e1d LW |
285 | #ifdef CONFIG_NETFILTER_INGRESS |
286 | if (hook == NF_NETDEV_INGRESS) | |
287 | return rcu_dereference(netdev->nf_hooks_ingress); | |
288 | #endif | |
289 | #ifdef CONFIG_NETFILTER_EGRESS | |
290 | if (hook == NF_NETDEV_EGRESS) | |
291 | return rcu_dereference(netdev->nf_hooks_egress); | |
292 | #endif | |
293 | fallthrough; | |
e2cf17d3 FW |
294 | #endif |
295 | default: | |
296 | return ERR_PTR(-EPROTONOSUPPORT); | |
297 | } | |
298 | ||
299 | return hook_head; | |
300 | } | |
301 | ||
302 | static int nfnl_hook_dump(struct sk_buff *nlskb, | |
303 | struct netlink_callback *cb) | |
304 | { | |
305 | struct nfgenmsg *nfmsg = nlmsg_data(cb->nlh); | |
306 | struct nfnl_dump_hook_data *ctx = cb->data; | |
307 | int err, family = nfmsg->nfgen_family; | |
308 | struct net *net = sock_net(nlskb->sk); | |
309 | struct nf_hook_ops * const *ops; | |
310 | const struct nf_hook_entries *e; | |
311 | unsigned int i = cb->args[0]; | |
312 | ||
313 | rcu_read_lock(); | |
314 | ||
315 | e = nfnl_hook_entries_head(family, ctx->hook, net, ctx->devname); | |
316 | if (!e) | |
317 | goto done; | |
318 | ||
319 | if (IS_ERR(e)) { | |
320 | cb->seq++; | |
321 | goto done; | |
322 | } | |
323 | ||
324 | if ((unsigned long)e != ctx->headv || i >= e->num_hook_entries) | |
325 | cb->seq++; | |
326 | ||
327 | ops = nf_hook_entries_get_hook_ops(e); | |
328 | ||
329 | for (; i < e->num_hook_entries; i++) { | |
69311e7c | 330 | err = nfnl_hook_dump_one(nlskb, ctx, ops[i], family, |
3d9bbaf6 | 331 | cb->nlh->nlmsg_seq); |
e2cf17d3 FW |
332 | if (err) |
333 | break; | |
334 | } | |
335 | ||
336 | done: | |
337 | nl_dump_check_consistent(cb, nlmsg_hdr(nlskb)); | |
338 | rcu_read_unlock(); | |
339 | cb->args[0] = i; | |
340 | return nlskb->len; | |
341 | } | |
342 | ||
343 | static int nfnl_hook_dump_start(struct netlink_callback *cb) | |
344 | { | |
345 | const struct nfgenmsg *nfmsg = nlmsg_data(cb->nlh); | |
346 | const struct nlattr * const *nla = cb->data; | |
347 | struct nfnl_dump_hook_data *ctx = NULL; | |
348 | struct net *net = sock_net(cb->skb->sk); | |
349 | u8 family = nfmsg->nfgen_family; | |
350 | char name[IFNAMSIZ] = ""; | |
351 | const void *head; | |
352 | u32 hooknum; | |
353 | ||
354 | hooknum = ntohl(nla_get_be32(nla[NFNLA_HOOK_HOOKNUM])); | |
355 | if (hooknum > 255) | |
356 | return -EINVAL; | |
357 | ||
358 | if (family == NFPROTO_NETDEV) { | |
359 | if (!nla[NFNLA_HOOK_DEV]) | |
360 | return -EINVAL; | |
361 | ||
362 | nla_strscpy(name, nla[NFNLA_HOOK_DEV], sizeof(name)); | |
363 | } | |
364 | ||
365 | rcu_read_lock(); | |
366 | /* Not dereferenced; for consistency check only */ | |
367 | head = nfnl_hook_entries_head(family, hooknum, net, name); | |
368 | rcu_read_unlock(); | |
369 | ||
370 | if (head && IS_ERR(head)) | |
371 | return PTR_ERR(head); | |
372 | ||
373 | ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); | |
374 | if (!ctx) | |
375 | return -ENOMEM; | |
376 | ||
377 | strscpy(ctx->devname, name, sizeof(ctx->devname)); | |
378 | ctx->headv = (unsigned long)head; | |
379 | ctx->hook = hooknum; | |
380 | ||
381 | cb->seq = 1; | |
382 | cb->data = ctx; | |
383 | ||
384 | return 0; | |
385 | } | |
386 | ||
387 | static int nfnl_hook_dump_stop(struct netlink_callback *cb) | |
388 | { | |
389 | kfree(cb->data); | |
390 | return 0; | |
391 | } | |
392 | ||
393 | static int nfnl_hook_get(struct sk_buff *skb, | |
394 | const struct nfnl_info *info, | |
395 | const struct nlattr * const nla[]) | |
396 | { | |
397 | if (!nla[NFNLA_HOOK_HOOKNUM]) | |
398 | return -EINVAL; | |
399 | ||
400 | if (info->nlh->nlmsg_flags & NLM_F_DUMP) { | |
401 | struct netlink_dump_control c = { | |
402 | .start = nfnl_hook_dump_start, | |
403 | .done = nfnl_hook_dump_stop, | |
404 | .dump = nfnl_hook_dump, | |
405 | .module = THIS_MODULE, | |
406 | .data = (void *)nla, | |
407 | }; | |
408 | ||
409 | return nf_netlink_dump_start_rcu(info->sk, skb, info->nlh, &c); | |
410 | } | |
411 | ||
412 | return -EOPNOTSUPP; | |
413 | } | |
414 | ||
415 | static const struct nfnl_callback nfnl_hook_cb[NFNL_MSG_HOOK_MAX] = { | |
416 | [NFNL_MSG_HOOK_GET] = { | |
417 | .call = nfnl_hook_get, | |
418 | .type = NFNL_CB_RCU, | |
419 | .attr_count = NFNLA_HOOK_MAX, | |
420 | .policy = nfnl_hook_nla_policy | |
421 | }, | |
422 | }; | |
423 | ||
424 | static const struct nfnetlink_subsystem nfhook_subsys = { | |
425 | .name = "nfhook", | |
426 | .subsys_id = NFNL_SUBSYS_HOOK, | |
427 | .cb_count = NFNL_MSG_HOOK_MAX, | |
428 | .cb = nfnl_hook_cb, | |
429 | }; | |
430 | ||
431 | MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_HOOK); | |
432 | ||
433 | static int __init nfnetlink_hook_init(void) | |
434 | { | |
435 | return nfnetlink_subsys_register(&nfhook_subsys); | |
436 | } | |
437 | ||
438 | static void __exit nfnetlink_hook_exit(void) | |
439 | { | |
440 | nfnetlink_subsys_unregister(&nfhook_subsys); | |
441 | } | |
442 | ||
443 | module_init(nfnetlink_hook_init); | |
444 | module_exit(nfnetlink_hook_exit); | |
445 | ||
446 | MODULE_LICENSE("GPL"); | |
447 | MODULE_AUTHOR("Florian Westphal <fw@strlen.de>"); | |
448 | MODULE_DESCRIPTION("nfnetlink_hook: list registered netfilter hooks"); |