1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
4  *
5  * Development of this code funded by Astaro AG (http://www.astaro.com/)
6  */
7 
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/init.h>
11 #include <linux/list.h>
12 #include <linux/rculist.h>
13 #include <linux/skbuff.h>
14 #include <linux/netlink.h>
15 #include <linux/netfilter.h>
16 #include <linux/static_key.h>
17 #include <linux/netfilter/nfnetlink.h>
18 #include <linux/netfilter/nf_tables.h>
19 #include <net/netfilter/nf_tables_core.h>
20 #include <net/netfilter/nf_tables.h>
21 #include <net/netfilter/nf_log.h>
22 #include <net/netfilter/nft_meta.h>
23 
24 static noinline void __nft_trace_packet(struct nft_traceinfo *info,
25 					const struct nft_chain *chain,
26 					enum nft_trace_types type)
27 {
28 	if (!info->trace || !info->nf_trace)
29 		return;
30 
31 	info->chain = chain;
32 	info->type = type;
33 
34 	nft_trace_notify(info);
35 }
36 
37 static inline void nft_trace_packet(const struct nft_pktinfo *pkt,
38 				    struct nft_traceinfo *info,
39 				    const struct nft_chain *chain,
40 				    const struct nft_rule_dp *rule,
41 				    enum nft_trace_types type)
42 {
43 	if (static_branch_unlikely(&nft_trace_enabled)) {
44 		info->nf_trace = pkt->skb->nf_trace;
45 		info->rule = rule;
46 		__nft_trace_packet(info, chain, type);
47 	}
48 }
49 
50 static inline void nft_trace_copy_nftrace(const struct nft_pktinfo *pkt,
51 					  struct nft_traceinfo *info)
52 {
53 	if (static_branch_unlikely(&nft_trace_enabled)) {
54 		if (info->trace)
55 			info->nf_trace = pkt->skb->nf_trace;
56 	}
57 }
58 
59 static void nft_bitwise_fast_eval(const struct nft_expr *expr,
60 				  struct nft_regs *regs)
61 {
62 	const struct nft_bitwise_fast_expr *priv = nft_expr_priv(expr);
63 	u32 *src = &regs->data[priv->sreg];
64 	u32 *dst = &regs->data[priv->dreg];
65 
66 	*dst = (*src & priv->mask) ^ priv->xor;
67 }
68 
69 static void nft_cmp_fast_eval(const struct nft_expr *expr,
70 			      struct nft_regs *regs)
71 {
72 	const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
73 
74 	if (((regs->data[priv->sreg] & priv->mask) == priv->data) ^ priv->inv)
75 		return;
76 	regs->verdict.code = NFT_BREAK;
77 }
78 
79 static void nft_cmp16_fast_eval(const struct nft_expr *expr,
80 				struct nft_regs *regs)
81 {
82 	const struct nft_cmp16_fast_expr *priv = nft_expr_priv(expr);
83 	const u64 *reg_data = (const u64 *)&regs->data[priv->sreg];
84 	const u64 *mask = (const u64 *)&priv->mask;
85 	const u64 *data = (const u64 *)&priv->data;
86 
87 	if (((reg_data[0] & mask[0]) == data[0] &&
88 	    ((reg_data[1] & mask[1]) == data[1])) ^ priv->inv)
89 		return;
90 	regs->verdict.code = NFT_BREAK;
91 }
92 
93 static noinline void __nft_trace_verdict(struct nft_traceinfo *info,
94 					 const struct nft_chain *chain,
95 					 const struct nft_regs *regs)
96 {
97 	enum nft_trace_types type;
98 
99 	switch (regs->verdict.code) {
100 	case NFT_CONTINUE:
101 	case NFT_RETURN:
102 		type = NFT_TRACETYPE_RETURN;
103 		break;
104 	case NF_STOLEN:
105 		type = NFT_TRACETYPE_RULE;
106 		/* can't access skb->nf_trace; use copy */
107 		break;
108 	default:
109 		type = NFT_TRACETYPE_RULE;
110 
111 		if (info->trace)
112 			info->nf_trace = info->pkt->skb->nf_trace;
113 		break;
114 	}
115 
116 	__nft_trace_packet(info, chain, type);
117 }
118 
119 static inline void nft_trace_verdict(struct nft_traceinfo *info,
120 				     const struct nft_chain *chain,
121 				     const struct nft_rule_dp *rule,
122 				     const struct nft_regs *regs)
123 {
124 	if (static_branch_unlikely(&nft_trace_enabled)) {
125 		info->rule = rule;
126 		__nft_trace_verdict(info, chain, regs);
127 	}
128 }
129 
130 static bool nft_payload_fast_eval(const struct nft_expr *expr,
131 				  struct nft_regs *regs,
132 				  const struct nft_pktinfo *pkt)
133 {
134 	const struct nft_payload *priv = nft_expr_priv(expr);
135 	const struct sk_buff *skb = pkt->skb;
136 	u32 *dest = &regs->data[priv->dreg];
137 	unsigned char *ptr;
138 
139 	if (priv->base == NFT_PAYLOAD_NETWORK_HEADER)
140 		ptr = skb_network_header(skb);
141 	else {
142 		if (!(pkt->flags & NFT_PKTINFO_L4PROTO))
143 			return false;
144 		ptr = skb_network_header(skb) + nft_thoff(pkt);
145 	}
146 
147 	ptr += priv->offset;
148 
149 	if (unlikely(ptr + priv->len > skb_tail_pointer(skb)))
150 		return false;
151 
152 	*dest = 0;
153 	if (priv->len == 2)
154 		*(u16 *)dest = *(u16 *)ptr;
155 	else if (priv->len == 4)
156 		*(u32 *)dest = *(u32 *)ptr;
157 	else
158 		*(u8 *)dest = *(u8 *)ptr;
159 	return true;
160 }
161 
162 DEFINE_STATIC_KEY_FALSE(nft_counters_enabled);
163 
164 static noinline void nft_update_chain_stats(const struct nft_chain *chain,
165 					    const struct nft_pktinfo *pkt)
166 {
167 	struct nft_base_chain *base_chain;
168 	struct nft_stats __percpu *pstats;
169 	struct nft_stats *stats;
170 
171 	base_chain = nft_base_chain(chain);
172 
173 	pstats = READ_ONCE(base_chain->stats);
174 	if (pstats) {
175 		local_bh_disable();
176 		stats = this_cpu_ptr(pstats);
177 		u64_stats_update_begin(&stats->syncp);
178 		stats->pkts++;
179 		stats->bytes += pkt->skb->len;
180 		u64_stats_update_end(&stats->syncp);
181 		local_bh_enable();
182 	}
183 }
184 
185 struct nft_jumpstack {
186 	const struct nft_chain *chain;
187 	const struct nft_rule_dp *rule;
188 	const struct nft_rule_dp *last_rule;
189 };
190 
191 static void expr_call_ops_eval(const struct nft_expr *expr,
192 			       struct nft_regs *regs,
193 			       struct nft_pktinfo *pkt)
194 {
195 #ifdef CONFIG_RETPOLINE
196 	unsigned long e = (unsigned long)expr->ops->eval;
197 #define X(e, fun) \
198 	do { if ((e) == (unsigned long)(fun)) \
199 		return fun(expr, regs, pkt); } while (0)
200 
201 	X(e, nft_payload_eval);
202 	X(e, nft_cmp_eval);
203 	X(e, nft_counter_eval);
204 	X(e, nft_meta_get_eval);
205 	X(e, nft_lookup_eval);
206 	X(e, nft_range_eval);
207 	X(e, nft_immediate_eval);
208 	X(e, nft_byteorder_eval);
209 	X(e, nft_dynset_eval);
210 	X(e, nft_rt_get_eval);
211 	X(e, nft_bitwise_eval);
212 #undef  X
213 #endif /* CONFIG_RETPOLINE */
214 	expr->ops->eval(expr, regs, pkt);
215 }
216 
217 #define nft_rule_expr_first(rule)	(struct nft_expr *)&rule->data[0]
218 #define nft_rule_expr_next(expr)	((void *)expr) + expr->ops->size
219 #define nft_rule_expr_last(rule)	(struct nft_expr *)&rule->data[rule->dlen]
220 #define nft_rule_next(rule)		(void *)rule + sizeof(*rule) + rule->dlen
221 
222 #define nft_rule_dp_for_each_expr(expr, last, rule) \
223         for ((expr) = nft_rule_expr_first(rule), (last) = nft_rule_expr_last(rule); \
224              (expr) != (last); \
225              (expr) = nft_rule_expr_next(expr))
226 
227 unsigned int
228 nft_do_chain(struct nft_pktinfo *pkt, void *priv)
229 {
230 	const struct nft_chain *chain = priv, *basechain = chain;
231 	const struct nft_rule_dp *rule, *last_rule;
232 	const struct net *net = nft_net(pkt);
233 	const struct nft_expr *expr, *last;
234 	struct nft_regs regs = {};
235 	unsigned int stackptr = 0;
236 	struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
237 	bool genbit = READ_ONCE(net->nft.gencursor);
238 	struct nft_rule_blob *blob;
239 	struct nft_traceinfo info;
240 
241 	info.trace = false;
242 	if (static_branch_unlikely(&nft_trace_enabled))
243 		nft_trace_init(&info, pkt, &regs.verdict, basechain);
244 do_chain:
245 	if (genbit)
246 		blob = rcu_dereference(chain->blob_gen_1);
247 	else
248 		blob = rcu_dereference(chain->blob_gen_0);
249 
250 	rule = (struct nft_rule_dp *)blob->data;
251 	last_rule = (void *)blob->data + blob->size;
252 next_rule:
253 	regs.verdict.code = NFT_CONTINUE;
254 	for (; rule < last_rule; rule = nft_rule_next(rule)) {
255 		nft_rule_dp_for_each_expr(expr, last, rule) {
256 			if (expr->ops == &nft_cmp_fast_ops)
257 				nft_cmp_fast_eval(expr, &regs);
258 			else if (expr->ops == &nft_cmp16_fast_ops)
259 				nft_cmp16_fast_eval(expr, &regs);
260 			else if (expr->ops == &nft_bitwise_fast_ops)
261 				nft_bitwise_fast_eval(expr, &regs);
262 			else if (expr->ops != &nft_payload_fast_ops ||
263 				 !nft_payload_fast_eval(expr, &regs, pkt))
264 				expr_call_ops_eval(expr, &regs, pkt);
265 
266 			if (regs.verdict.code != NFT_CONTINUE)
267 				break;
268 		}
269 
270 		switch (regs.verdict.code) {
271 		case NFT_BREAK:
272 			regs.verdict.code = NFT_CONTINUE;
273 			nft_trace_copy_nftrace(pkt, &info);
274 			continue;
275 		case NFT_CONTINUE:
276 			nft_trace_packet(pkt, &info, chain, rule,
277 					 NFT_TRACETYPE_RULE);
278 			continue;
279 		}
280 		break;
281 	}
282 
283 	nft_trace_verdict(&info, chain, rule, &regs);
284 
285 	switch (regs.verdict.code & NF_VERDICT_MASK) {
286 	case NF_ACCEPT:
287 	case NF_DROP:
288 	case NF_QUEUE:
289 	case NF_STOLEN:
290 		return regs.verdict.code;
291 	}
292 
293 	switch (regs.verdict.code) {
294 	case NFT_JUMP:
295 		if (WARN_ON_ONCE(stackptr >= NFT_JUMP_STACK_SIZE))
296 			return NF_DROP;
297 		jumpstack[stackptr].chain = chain;
298 		jumpstack[stackptr].rule = nft_rule_next(rule);
299 		jumpstack[stackptr].last_rule = last_rule;
300 		stackptr++;
301 		fallthrough;
302 	case NFT_GOTO:
303 		chain = regs.verdict.chain;
304 		goto do_chain;
305 	case NFT_CONTINUE:
306 	case NFT_RETURN:
307 		break;
308 	default:
309 		WARN_ON_ONCE(1);
310 	}
311 
312 	if (stackptr > 0) {
313 		stackptr--;
314 		chain = jumpstack[stackptr].chain;
315 		rule = jumpstack[stackptr].rule;
316 		last_rule = jumpstack[stackptr].last_rule;
317 		goto next_rule;
318 	}
319 
320 	nft_trace_packet(pkt, &info, basechain, NULL, NFT_TRACETYPE_POLICY);
321 
322 	if (static_branch_unlikely(&nft_counters_enabled))
323 		nft_update_chain_stats(basechain, pkt);
324 
325 	return nft_base_chain(basechain)->policy;
326 }
327 EXPORT_SYMBOL_GPL(nft_do_chain);
328 
329 static struct nft_expr_type *nft_basic_types[] = {
330 	&nft_imm_type,
331 	&nft_cmp_type,
332 	&nft_lookup_type,
333 	&nft_bitwise_type,
334 	&nft_byteorder_type,
335 	&nft_payload_type,
336 	&nft_dynset_type,
337 	&nft_range_type,
338 	&nft_meta_type,
339 	&nft_rt_type,
340 	&nft_exthdr_type,
341 	&nft_last_type,
342 	&nft_counter_type,
343 	&nft_objref_type,
344 	&nft_inner_type,
345 };
346 
347 static struct nft_object_type *nft_basic_objects[] = {
348 #ifdef CONFIG_NETWORK_SECMARK
349 	&nft_secmark_obj_type,
350 #endif
351 	&nft_counter_obj_type,
352 };
353 
354 int __init nf_tables_core_module_init(void)
355 {
356 	int err, i, j = 0;
357 
358 	nft_counter_init_seqcount();
359 
360 	for (i = 0; i < ARRAY_SIZE(nft_basic_objects); i++) {
361 		err = nft_register_obj(nft_basic_objects[i]);
362 		if (err)
363 			goto err;
364 	}
365 
366 	for (j = 0; j < ARRAY_SIZE(nft_basic_types); j++) {
367 		err = nft_register_expr(nft_basic_types[j]);
368 		if (err)
369 			goto err;
370 	}
371 
372 	return 0;
373 
374 err:
375 	while (j-- > 0)
376 		nft_unregister_expr(nft_basic_types[j]);
377 
378 	while (i-- > 0)
379 		nft_unregister_obj(nft_basic_objects[i]);
380 
381 	return err;
382 }
383 
384 void nf_tables_core_module_exit(void)
385 {
386 	int i;
387 
388 	i = ARRAY_SIZE(nft_basic_types);
389 	while (i-- > 0)
390 		nft_unregister_expr(nft_basic_types[i]);
391 
392 	i = ARRAY_SIZE(nft_basic_objects);
393 	while (i-- > 0)
394 		nft_unregister_obj(nft_basic_objects[i]);
395 }
396