1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
4 * Copyright (c) 2012-2014 Pablo Neira Ayuso <pablo@netfilter.org>
5 *
6 * Development of this code funded by Astaro AG (http://www.astaro.com/)
7 */
8
9#include <linux/audit.h>
10#include <linux/kernel.h>
11#include <linux/init.h>
12#include <linux/module.h>
13#include <linux/netlink.h>
14#include <linux/netfilter.h>
15#include <linux/netfilter/nf_tables.h>
16#include <net/ipv6.h>
17#include <net/ip.h>
18#include <net/netfilter/nf_tables.h>
19#include <net/netfilter/nf_log.h>
20#include <linux/netdevice.h>
21
22static const char *nft_log_null_prefix = "";
23
24struct nft_log {
25	struct nf_loginfo	loginfo;
26	char			*prefix;
27};
28
29static bool audit_ip4(struct audit_buffer *ab, struct sk_buff *skb)
30{
31	struct iphdr _iph;
32	const struct iphdr *ih;
33
34	ih = skb_header_pointer(skb, skb_network_offset(skb), sizeof(_iph), &_iph);
35	if (!ih)
36		return false;
37
38	audit_log_format(ab, " saddr=%pI4 daddr=%pI4 proto=%hhu",
39			 &ih->saddr, &ih->daddr, ih->protocol);
40
41	return true;
42}
43
44static bool audit_ip6(struct audit_buffer *ab, struct sk_buff *skb)
45{
46	struct ipv6hdr _ip6h;
47	const struct ipv6hdr *ih;
48	u8 nexthdr;
49	__be16 frag_off;
50
51	ih = skb_header_pointer(skb, skb_network_offset(skb), sizeof(_ip6h), &_ip6h);
52	if (!ih)
53		return false;
54
55	nexthdr = ih->nexthdr;
56	ipv6_skip_exthdr(skb, skb_network_offset(skb) + sizeof(_ip6h), &nexthdr, &frag_off);
57
58	audit_log_format(ab, " saddr=%pI6c daddr=%pI6c proto=%hhu",
59			 &ih->saddr, &ih->daddr, nexthdr);
60
61	return true;
62}
63
64static void nft_log_eval_audit(const struct nft_pktinfo *pkt)
65{
66	struct sk_buff *skb = pkt->skb;
67	struct audit_buffer *ab;
68	int fam = -1;
69
70	if (!audit_enabled)
71		return;
72
73	ab = audit_log_start(NULL, GFP_ATOMIC, AUDIT_NETFILTER_PKT);
74	if (!ab)
75		return;
76
77	audit_log_format(ab, "mark=%#x", skb->mark);
78
79	switch (nft_pf(pkt)) {
80	case NFPROTO_BRIDGE:
81		switch (eth_hdr(skb)->h_proto) {
82		case htons(ETH_P_IP):
83			fam = audit_ip4(ab, skb) ? NFPROTO_IPV4 : -1;
84			break;
85		case htons(ETH_P_IPV6):
86			fam = audit_ip6(ab, skb) ? NFPROTO_IPV6 : -1;
87			break;
88		}
89		break;
90	case NFPROTO_IPV4:
91		fam = audit_ip4(ab, skb) ? NFPROTO_IPV4 : -1;
92		break;
93	case NFPROTO_IPV6:
94		fam = audit_ip6(ab, skb) ? NFPROTO_IPV6 : -1;
95		break;
96	}
97
98	if (fam == -1)
99		audit_log_format(ab, " saddr=? daddr=? proto=-1");
100
101	audit_log_end(ab);
102}
103
104static void nft_log_eval(const struct nft_expr *expr,
105			 struct nft_regs *regs,
106			 const struct nft_pktinfo *pkt)
107{
108	const struct nft_log *priv = nft_expr_priv(expr);
109
110	if (priv->loginfo.type == NF_LOG_TYPE_LOG &&
111	    priv->loginfo.u.log.level == NFT_LOGLEVEL_AUDIT) {
112		nft_log_eval_audit(pkt);
113		return;
114	}
115
116	nf_log_packet(nft_net(pkt), nft_pf(pkt), nft_hook(pkt), pkt->skb,
117		      nft_in(pkt), nft_out(pkt), &priv->loginfo, "%s",
118		      priv->prefix);
119}
120
121static const struct nla_policy nft_log_policy[NFTA_LOG_MAX + 1] = {
122	[NFTA_LOG_GROUP]	= { .type = NLA_U16 },
123	[NFTA_LOG_PREFIX]	= { .type = NLA_STRING,
124				    .len = NF_LOG_PREFIXLEN - 1 },
125	[NFTA_LOG_SNAPLEN]	= { .type = NLA_U32 },
126	[NFTA_LOG_QTHRESHOLD]	= { .type = NLA_U16 },
127	[NFTA_LOG_LEVEL]	= { .type = NLA_U32 },
128	[NFTA_LOG_FLAGS]	= { .type = NLA_U32 },
129};
130
131static int nft_log_modprobe(struct net *net, enum nf_log_type t)
132{
133	switch (t) {
134	case NF_LOG_TYPE_LOG:
135		return nft_request_module(net, "%s", "nf_log_syslog");
136	case NF_LOG_TYPE_ULOG:
137		return nft_request_module(net, "%s", "nfnetlink_log");
138	case NF_LOG_TYPE_MAX:
139		break;
140	}
141
142	return -ENOENT;
143}
144
145static int nft_log_init(const struct nft_ctx *ctx,
146			const struct nft_expr *expr,
147			const struct nlattr * const tb[])
148{
149	struct nft_log *priv = nft_expr_priv(expr);
150	struct nf_loginfo *li = &priv->loginfo;
151	const struct nlattr *nla;
152	int err;
153
154	li->type = NF_LOG_TYPE_LOG;
155	if (tb[NFTA_LOG_LEVEL] != NULL &&
156	    tb[NFTA_LOG_GROUP] != NULL)
157		return -EINVAL;
158	if (tb[NFTA_LOG_GROUP] != NULL) {
159		li->type = NF_LOG_TYPE_ULOG;
160		if (tb[NFTA_LOG_FLAGS] != NULL)
161			return -EINVAL;
162	}
163
164	nla = tb[NFTA_LOG_PREFIX];
165	if (nla != NULL) {
166		priv->prefix = kmalloc(nla_len(nla) + 1, GFP_KERNEL);
167		if (priv->prefix == NULL)
168			return -ENOMEM;
169		nla_strscpy(priv->prefix, nla, nla_len(nla) + 1);
170	} else {
171		priv->prefix = (char *)nft_log_null_prefix;
172	}
173
174	switch (li->type) {
175	case NF_LOG_TYPE_LOG:
176		if (tb[NFTA_LOG_LEVEL] != NULL) {
177			li->u.log.level =
178				ntohl(nla_get_be32(tb[NFTA_LOG_LEVEL]));
179		} else {
180			li->u.log.level = NFT_LOGLEVEL_WARNING;
181		}
182		if (li->u.log.level > NFT_LOGLEVEL_AUDIT) {
183			err = -EINVAL;
184			goto err1;
185		}
186
187		if (tb[NFTA_LOG_FLAGS] != NULL) {
188			li->u.log.logflags =
189				ntohl(nla_get_be32(tb[NFTA_LOG_FLAGS]));
190			if (li->u.log.logflags & ~NF_LOG_MASK) {
191				err = -EINVAL;
192				goto err1;
193			}
194		}
195		break;
196	case NF_LOG_TYPE_ULOG:
197		li->u.ulog.group = ntohs(nla_get_be16(tb[NFTA_LOG_GROUP]));
198		if (tb[NFTA_LOG_SNAPLEN] != NULL) {
199			li->u.ulog.flags |= NF_LOG_F_COPY_LEN;
200			li->u.ulog.copy_len =
201				ntohl(nla_get_be32(tb[NFTA_LOG_SNAPLEN]));
202		}
203		if (tb[NFTA_LOG_QTHRESHOLD] != NULL) {
204			li->u.ulog.qthreshold =
205				ntohs(nla_get_be16(tb[NFTA_LOG_QTHRESHOLD]));
206		}
207		break;
208	}
209
210	if (li->u.log.level == NFT_LOGLEVEL_AUDIT)
211		return 0;
212
213	err = nf_logger_find_get(ctx->family, li->type);
214	if (err < 0) {
215		if (nft_log_modprobe(ctx->net, li->type) == -EAGAIN)
216			err = -EAGAIN;
217
218		goto err1;
219	}
220
221	return 0;
222
223err1:
224	if (priv->prefix != nft_log_null_prefix)
225		kfree(priv->prefix);
226	return err;
227}
228
229static void nft_log_destroy(const struct nft_ctx *ctx,
230			    const struct nft_expr *expr)
231{
232	struct nft_log *priv = nft_expr_priv(expr);
233	struct nf_loginfo *li = &priv->loginfo;
234
235	if (priv->prefix != nft_log_null_prefix)
236		kfree(priv->prefix);
237
238	if (li->u.log.level == NFT_LOGLEVEL_AUDIT)
239		return;
240
241	nf_logger_put(ctx->family, li->type);
242}
243
244static int nft_log_dump(struct sk_buff *skb,
245			const struct nft_expr *expr, bool reset)
246{
247	const struct nft_log *priv = nft_expr_priv(expr);
248	const struct nf_loginfo *li = &priv->loginfo;
249
250	if (priv->prefix != nft_log_null_prefix)
251		if (nla_put_string(skb, NFTA_LOG_PREFIX, priv->prefix))
252			goto nla_put_failure;
253	switch (li->type) {
254	case NF_LOG_TYPE_LOG:
255		if (nla_put_be32(skb, NFTA_LOG_LEVEL, htonl(li->u.log.level)))
256			goto nla_put_failure;
257
258		if (li->u.log.logflags) {
259			if (nla_put_be32(skb, NFTA_LOG_FLAGS,
260					 htonl(li->u.log.logflags)))
261				goto nla_put_failure;
262		}
263		break;
264	case NF_LOG_TYPE_ULOG:
265		if (nla_put_be16(skb, NFTA_LOG_GROUP, htons(li->u.ulog.group)))
266			goto nla_put_failure;
267
268		if (li->u.ulog.flags & NF_LOG_F_COPY_LEN) {
269			if (nla_put_be32(skb, NFTA_LOG_SNAPLEN,
270					 htonl(li->u.ulog.copy_len)))
271				goto nla_put_failure;
272		}
273		if (li->u.ulog.qthreshold) {
274			if (nla_put_be16(skb, NFTA_LOG_QTHRESHOLD,
275					 htons(li->u.ulog.qthreshold)))
276				goto nla_put_failure;
277		}
278		break;
279	}
280	return 0;
281
282nla_put_failure:
283	return -1;
284}
285
286static struct nft_expr_type nft_log_type;
287static const struct nft_expr_ops nft_log_ops = {
288	.type		= &nft_log_type,
289	.size		= NFT_EXPR_SIZE(sizeof(struct nft_log)),
290	.eval		= nft_log_eval,
291	.init		= nft_log_init,
292	.destroy	= nft_log_destroy,
293	.dump		= nft_log_dump,
294	.reduce		= NFT_REDUCE_READONLY,
295};
296
297static struct nft_expr_type nft_log_type __read_mostly = {
298	.name		= "log",
299	.ops		= &nft_log_ops,
300	.policy		= nft_log_policy,
301	.maxattr	= NFTA_LOG_MAX,
302	.owner		= THIS_MODULE,
303};
304
305static int __init nft_log_module_init(void)
306{
307	return nft_register_expr(&nft_log_type);
308}
309
310static void __exit nft_log_module_exit(void)
311{
312	nft_unregister_expr(&nft_log_type);
313}
314
315module_init(nft_log_module_init);
316module_exit(nft_log_module_exit);
317
318MODULE_LICENSE("GPL");
319MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
320MODULE_ALIAS_NFT_EXPR("log");
321MODULE_DESCRIPTION("Netfilter nf_tables log module");
322