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Linux/net/netfilter/nft_log.c

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  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 
 22 static const char *nft_log_null_prefix = "";
 23 
 24 struct nft_log {
 25         struct nf_loginfo       loginfo;
 26         char                    *prefix;
 27 };
 28 
 29 static 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 
 44 static 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 
 64 static 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 
104 static 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 
121 static 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 
131 static int nft_log_init(const struct nft_ctx *ctx,
132                         const struct nft_expr *expr,
133                         const struct nlattr * const tb[])
134 {
135         struct nft_log *priv = nft_expr_priv(expr);
136         struct nf_loginfo *li = &priv->loginfo;
137         const struct nlattr *nla;
138         int err;
139 
140         li->type = NF_LOG_TYPE_LOG;
141         if (tb[NFTA_LOG_LEVEL] != NULL &&
142             tb[NFTA_LOG_GROUP] != NULL)
143                 return -EINVAL;
144         if (tb[NFTA_LOG_GROUP] != NULL) {
145                 li->type = NF_LOG_TYPE_ULOG;
146                 if (tb[NFTA_LOG_FLAGS] != NULL)
147                         return -EINVAL;
148         }
149 
150         nla = tb[NFTA_LOG_PREFIX];
151         if (nla != NULL) {
152                 priv->prefix = kmalloc(nla_len(nla) + 1, GFP_KERNEL);
153                 if (priv->prefix == NULL)
154                         return -ENOMEM;
155                 nla_strlcpy(priv->prefix, nla, nla_len(nla) + 1);
156         } else {
157                 priv->prefix = (char *)nft_log_null_prefix;
158         }
159 
160         switch (li->type) {
161         case NF_LOG_TYPE_LOG:
162                 if (tb[NFTA_LOG_LEVEL] != NULL) {
163                         li->u.log.level =
164                                 ntohl(nla_get_be32(tb[NFTA_LOG_LEVEL]));
165                 } else {
166                         li->u.log.level = NFT_LOGLEVEL_WARNING;
167                 }
168                 if (li->u.log.level > NFT_LOGLEVEL_AUDIT) {
169                         err = -EINVAL;
170                         goto err1;
171                 }
172 
173                 if (tb[NFTA_LOG_FLAGS] != NULL) {
174                         li->u.log.logflags =
175                                 ntohl(nla_get_be32(tb[NFTA_LOG_FLAGS]));
176                         if (li->u.log.logflags & ~NF_LOG_MASK) {
177                                 err = -EINVAL;
178                                 goto err1;
179                         }
180                 }
181                 break;
182         case NF_LOG_TYPE_ULOG:
183                 li->u.ulog.group = ntohs(nla_get_be16(tb[NFTA_LOG_GROUP]));
184                 if (tb[NFTA_LOG_SNAPLEN] != NULL) {
185                         li->u.ulog.flags |= NF_LOG_F_COPY_LEN;
186                         li->u.ulog.copy_len =
187                                 ntohl(nla_get_be32(tb[NFTA_LOG_SNAPLEN]));
188                 }
189                 if (tb[NFTA_LOG_QTHRESHOLD] != NULL) {
190                         li->u.ulog.qthreshold =
191                                 ntohs(nla_get_be16(tb[NFTA_LOG_QTHRESHOLD]));
192                 }
193                 break;
194         }
195 
196         if (li->u.log.level == NFT_LOGLEVEL_AUDIT)
197                 return 0;
198 
199         err = nf_logger_find_get(ctx->family, li->type);
200         if (err < 0)
201                 goto err1;
202 
203         return 0;
204 
205 err1:
206         if (priv->prefix != nft_log_null_prefix)
207                 kfree(priv->prefix);
208         return err;
209 }
210 
211 static void nft_log_destroy(const struct nft_ctx *ctx,
212                             const struct nft_expr *expr)
213 {
214         struct nft_log *priv = nft_expr_priv(expr);
215         struct nf_loginfo *li = &priv->loginfo;
216 
217         if (priv->prefix != nft_log_null_prefix)
218                 kfree(priv->prefix);
219 
220         if (li->u.log.level == NFT_LOGLEVEL_AUDIT)
221                 return;
222 
223         nf_logger_put(ctx->family, li->type);
224 }
225 
226 static int nft_log_dump(struct sk_buff *skb, const struct nft_expr *expr)
227 {
228         const struct nft_log *priv = nft_expr_priv(expr);
229         const struct nf_loginfo *li = &priv->loginfo;
230 
231         if (priv->prefix != nft_log_null_prefix)
232                 if (nla_put_string(skb, NFTA_LOG_PREFIX, priv->prefix))
233                         goto nla_put_failure;
234         switch (li->type) {
235         case NF_LOG_TYPE_LOG:
236                 if (nla_put_be32(skb, NFTA_LOG_LEVEL, htonl(li->u.log.level)))
237                         goto nla_put_failure;
238 
239                 if (li->u.log.logflags) {
240                         if (nla_put_be32(skb, NFTA_LOG_FLAGS,
241                                          htonl(li->u.log.logflags)))
242                                 goto nla_put_failure;
243                 }
244                 break;
245         case NF_LOG_TYPE_ULOG:
246                 if (nla_put_be16(skb, NFTA_LOG_GROUP, htons(li->u.ulog.group)))
247                         goto nla_put_failure;
248 
249                 if (li->u.ulog.flags & NF_LOG_F_COPY_LEN) {
250                         if (nla_put_be32(skb, NFTA_LOG_SNAPLEN,
251                                          htonl(li->u.ulog.copy_len)))
252                                 goto nla_put_failure;
253                 }
254                 if (li->u.ulog.qthreshold) {
255                         if (nla_put_be16(skb, NFTA_LOG_QTHRESHOLD,
256                                          htons(li->u.ulog.qthreshold)))
257                                 goto nla_put_failure;
258                 }
259                 break;
260         }
261         return 0;
262 
263 nla_put_failure:
264         return -1;
265 }
266 
267 static struct nft_expr_type nft_log_type;
268 static const struct nft_expr_ops nft_log_ops = {
269         .type           = &nft_log_type,
270         .size           = NFT_EXPR_SIZE(sizeof(struct nft_log)),
271         .eval           = nft_log_eval,
272         .init           = nft_log_init,
273         .destroy        = nft_log_destroy,
274         .dump           = nft_log_dump,
275 };
276 
277 static struct nft_expr_type nft_log_type __read_mostly = {
278         .name           = "log",
279         .ops            = &nft_log_ops,
280         .policy         = nft_log_policy,
281         .maxattr        = NFTA_LOG_MAX,
282         .owner          = THIS_MODULE,
283 };
284 
285 static int __init nft_log_module_init(void)
286 {
287         return nft_register_expr(&nft_log_type);
288 }
289 
290 static void __exit nft_log_module_exit(void)
291 {
292         nft_unregister_expr(&nft_log_type);
293 }
294 
295 module_init(nft_log_module_init);
296 module_exit(nft_log_module_exit);
297 
298 MODULE_LICENSE("GPL");
299 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
300 MODULE_ALIAS_NFT_EXPR("log");
301 

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