1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * (C) 2015 Red Hat GmbH
4 * Author: Florian Westphal <fw@strlen.de>
5 */
6
7 #include <linux/module.h>
8 #include <linux/static_key.h>
9 #include <linux/hash.h>
10 #include <linux/siphash.h>
11 #include <linux/if_vlan.h>
12 #include <linux/init.h>
13 #include <linux/skbuff.h>
14 #include <linux/netlink.h>
15 #include <linux/netfilter.h>
16 #include <linux/netfilter/nfnetlink.h>
17 #include <linux/netfilter/nf_tables.h>
18 #include <net/netfilter/nf_tables_core.h>
19 #include <net/netfilter/nf_tables.h>
20
21 #define NFT_TRACETYPE_LL_HSIZE 20
22 #define NFT_TRACETYPE_NETWORK_HSIZE 40
23 #define NFT_TRACETYPE_TRANSPORT_HSIZE 20
24
25 DEFINE_STATIC_KEY_FALSE(nft_trace_enabled);
26 EXPORT_SYMBOL_GPL(nft_trace_enabled);
27
trace_fill_header(struct sk_buff * nlskb,u16 type,const struct sk_buff * skb,int off,unsigned int len)28 static int trace_fill_header(struct sk_buff *nlskb, u16 type,
29 const struct sk_buff *skb,
30 int off, unsigned int len)
31 {
32 struct nlattr *nla;
33
34 if (len == 0)
35 return 0;
36
37 nla = nla_reserve(nlskb, type, len);
38 if (!nla || skb_copy_bits(skb, off, nla_data(nla), len))
39 return -1;
40
41 return 0;
42 }
43
nf_trace_fill_ll_header(struct sk_buff * nlskb,const struct sk_buff * skb)44 static int nf_trace_fill_ll_header(struct sk_buff *nlskb,
45 const struct sk_buff *skb)
46 {
47 struct vlan_ethhdr veth;
48 int off;
49
50 BUILD_BUG_ON(sizeof(veth) > NFT_TRACETYPE_LL_HSIZE);
51
52 off = skb_mac_header(skb) - skb->data;
53 if (off != -ETH_HLEN)
54 return -1;
55
56 if (skb_copy_bits(skb, off, &veth, ETH_HLEN))
57 return -1;
58
59 veth.h_vlan_proto = skb->vlan_proto;
60 veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
61 veth.h_vlan_encapsulated_proto = skb->protocol;
62
63 return nla_put(nlskb, NFTA_TRACE_LL_HEADER, sizeof(veth), &veth);
64 }
65
nf_trace_fill_dev_info(struct sk_buff * nlskb,const struct net_device * indev,const struct net_device * outdev)66 static int nf_trace_fill_dev_info(struct sk_buff *nlskb,
67 const struct net_device *indev,
68 const struct net_device *outdev)
69 {
70 if (indev) {
71 if (nla_put_be32(nlskb, NFTA_TRACE_IIF,
72 htonl(indev->ifindex)))
73 return -1;
74
75 if (nla_put_be16(nlskb, NFTA_TRACE_IIFTYPE,
76 htons(indev->type)))
77 return -1;
78 }
79
80 if (outdev) {
81 if (nla_put_be32(nlskb, NFTA_TRACE_OIF,
82 htonl(outdev->ifindex)))
83 return -1;
84
85 if (nla_put_be16(nlskb, NFTA_TRACE_OIFTYPE,
86 htons(outdev->type)))
87 return -1;
88 }
89
90 return 0;
91 }
92
nf_trace_fill_pkt_info(struct sk_buff * nlskb,const struct nft_pktinfo * pkt)93 static int nf_trace_fill_pkt_info(struct sk_buff *nlskb,
94 const struct nft_pktinfo *pkt)
95 {
96 const struct sk_buff *skb = pkt->skb;
97 int off = skb_network_offset(skb);
98 unsigned int len, nh_end;
99
100 nh_end = pkt->flags & NFT_PKTINFO_L4PROTO ? nft_thoff(pkt) : skb->len;
101 len = min_t(unsigned int, nh_end - skb_network_offset(skb),
102 NFT_TRACETYPE_NETWORK_HSIZE);
103 if (trace_fill_header(nlskb, NFTA_TRACE_NETWORK_HEADER, skb, off, len))
104 return -1;
105
106 if (pkt->flags & NFT_PKTINFO_L4PROTO) {
107 len = min_t(unsigned int, skb->len - nft_thoff(pkt),
108 NFT_TRACETYPE_TRANSPORT_HSIZE);
109 if (trace_fill_header(nlskb, NFTA_TRACE_TRANSPORT_HEADER, skb,
110 nft_thoff(pkt), len))
111 return -1;
112 }
113
114 if (!skb_mac_header_was_set(skb))
115 return 0;
116
117 if (skb_vlan_tag_get(skb))
118 return nf_trace_fill_ll_header(nlskb, skb);
119
120 off = skb_mac_header(skb) - skb->data;
121 len = min_t(unsigned int, -off, NFT_TRACETYPE_LL_HSIZE);
122 return trace_fill_header(nlskb, NFTA_TRACE_LL_HEADER,
123 skb, off, len);
124 }
125
nf_trace_fill_rule_info(struct sk_buff * nlskb,const struct nft_verdict * verdict,const struct nft_rule_dp * rule,const struct nft_traceinfo * info)126 static int nf_trace_fill_rule_info(struct sk_buff *nlskb,
127 const struct nft_verdict *verdict,
128 const struct nft_rule_dp *rule,
129 const struct nft_traceinfo *info)
130 {
131 if (!rule || rule->is_last)
132 return 0;
133
134 /* a continue verdict with ->type == RETURN means that this is
135 * an implicit return (end of chain reached).
136 *
137 * Since no rule matched, the ->rule pointer is invalid.
138 */
139 if (info->type == NFT_TRACETYPE_RETURN &&
140 verdict->code == NFT_CONTINUE)
141 return 0;
142
143 return nla_put_be64(nlskb, NFTA_TRACE_RULE_HANDLE,
144 cpu_to_be64(rule->handle),
145 NFTA_TRACE_PAD);
146 }
147
nft_trace_have_verdict_chain(const struct nft_verdict * verdict,struct nft_traceinfo * info)148 static bool nft_trace_have_verdict_chain(const struct nft_verdict *verdict,
149 struct nft_traceinfo *info)
150 {
151 switch (info->type) {
152 case NFT_TRACETYPE_RETURN:
153 case NFT_TRACETYPE_RULE:
154 break;
155 default:
156 return false;
157 }
158
159 switch (verdict->code) {
160 case NFT_JUMP:
161 case NFT_GOTO:
162 break;
163 default:
164 return false;
165 }
166
167 return true;
168 }
169
nft_trace_get_chain(const struct nft_rule_dp * rule,const struct nft_traceinfo * info)170 static const struct nft_chain *nft_trace_get_chain(const struct nft_rule_dp *rule,
171 const struct nft_traceinfo *info)
172 {
173 const struct nft_rule_dp_last *last;
174
175 if (!rule)
176 return &info->basechain->chain;
177
178 while (!rule->is_last)
179 rule = nft_rule_next(rule);
180
181 last = (const struct nft_rule_dp_last *)rule;
182
183 if (WARN_ON_ONCE(!last->chain))
184 return &info->basechain->chain;
185
186 return last->chain;
187 }
188
nft_trace_notify(const struct nft_pktinfo * pkt,const struct nft_verdict * verdict,const struct nft_rule_dp * rule,struct nft_traceinfo * info)189 void nft_trace_notify(const struct nft_pktinfo *pkt,
190 const struct nft_verdict *verdict,
191 const struct nft_rule_dp *rule,
192 struct nft_traceinfo *info)
193 {
194 const struct nft_chain *chain;
195 struct nlmsghdr *nlh;
196 struct sk_buff *skb;
197 unsigned int size;
198 u32 mark = 0;
199 u16 event;
200
201 if (!nfnetlink_has_listeners(nft_net(pkt), NFNLGRP_NFTRACE))
202 return;
203
204 chain = nft_trace_get_chain(rule, info);
205
206 size = nlmsg_total_size(sizeof(struct nfgenmsg)) +
207 nla_total_size(strlen(chain->table->name)) +
208 nla_total_size(strlen(chain->name)) +
209 nla_total_size_64bit(sizeof(__be64)) + /* rule handle */
210 nla_total_size(sizeof(__be32)) + /* trace type */
211 nla_total_size(0) + /* VERDICT, nested */
212 nla_total_size(sizeof(u32)) + /* verdict code */
213 nla_total_size(sizeof(u32)) + /* id */
214 nla_total_size(NFT_TRACETYPE_LL_HSIZE) +
215 nla_total_size(NFT_TRACETYPE_NETWORK_HSIZE) +
216 nla_total_size(NFT_TRACETYPE_TRANSPORT_HSIZE) +
217 nla_total_size(sizeof(u32)) + /* iif */
218 nla_total_size(sizeof(__be16)) + /* iiftype */
219 nla_total_size(sizeof(u32)) + /* oif */
220 nla_total_size(sizeof(__be16)) + /* oiftype */
221 nla_total_size(sizeof(u32)) + /* mark */
222 nla_total_size(sizeof(u32)) + /* nfproto */
223 nla_total_size(sizeof(u32)); /* policy */
224
225 if (nft_trace_have_verdict_chain(verdict, info))
226 size += nla_total_size(strlen(verdict->chain->name)); /* jump target */
227
228 skb = nlmsg_new(size, GFP_ATOMIC);
229 if (!skb)
230 return;
231
232 event = nfnl_msg_type(NFNL_SUBSYS_NFTABLES, NFT_MSG_TRACE);
233 nlh = nfnl_msg_put(skb, 0, 0, event, 0, info->basechain->type->family,
234 NFNETLINK_V0, 0);
235 if (!nlh)
236 goto nla_put_failure;
237
238 if (nla_put_be32(skb, NFTA_TRACE_NFPROTO, htonl(nft_pf(pkt))))
239 goto nla_put_failure;
240
241 if (nla_put_be32(skb, NFTA_TRACE_TYPE, htonl(info->type)))
242 goto nla_put_failure;
243
244 if (nla_put_u32(skb, NFTA_TRACE_ID, info->skbid))
245 goto nla_put_failure;
246
247 if (nla_put_string(skb, NFTA_TRACE_CHAIN, chain->name))
248 goto nla_put_failure;
249
250 if (nla_put_string(skb, NFTA_TRACE_TABLE, chain->table->name))
251 goto nla_put_failure;
252
253 if (nf_trace_fill_rule_info(skb, verdict, rule, info))
254 goto nla_put_failure;
255
256 switch (info->type) {
257 case NFT_TRACETYPE_UNSPEC:
258 case __NFT_TRACETYPE_MAX:
259 break;
260 case NFT_TRACETYPE_RETURN:
261 case NFT_TRACETYPE_RULE: {
262 unsigned int v;
263
264 if (nft_verdict_dump(skb, NFTA_TRACE_VERDICT, verdict))
265 goto nla_put_failure;
266
267 /* pkt->skb undefined iff NF_STOLEN, disable dump */
268 v = verdict->code & NF_VERDICT_MASK;
269 if (v == NF_STOLEN)
270 info->packet_dumped = true;
271 else
272 mark = pkt->skb->mark;
273
274 break;
275 }
276 case NFT_TRACETYPE_POLICY:
277 mark = pkt->skb->mark;
278
279 if (nla_put_be32(skb, NFTA_TRACE_POLICY,
280 htonl(info->basechain->policy)))
281 goto nla_put_failure;
282 break;
283 }
284
285 if (mark && nla_put_be32(skb, NFTA_TRACE_MARK, htonl(mark)))
286 goto nla_put_failure;
287
288 if (!info->packet_dumped) {
289 if (nf_trace_fill_dev_info(skb, nft_in(pkt), nft_out(pkt)))
290 goto nla_put_failure;
291
292 if (nf_trace_fill_pkt_info(skb, pkt))
293 goto nla_put_failure;
294 info->packet_dumped = true;
295 }
296
297 nlmsg_end(skb, nlh);
298 nfnetlink_send(skb, nft_net(pkt), 0, NFNLGRP_NFTRACE, 0, GFP_ATOMIC);
299 return;
300
301 nla_put_failure:
302 WARN_ON_ONCE(1);
303 kfree_skb(skb);
304 }
305
nft_trace_init(struct nft_traceinfo * info,const struct nft_pktinfo * pkt,const struct nft_chain * chain)306 void nft_trace_init(struct nft_traceinfo *info, const struct nft_pktinfo *pkt,
307 const struct nft_chain *chain)
308 {
309 static siphash_key_t trace_key __read_mostly;
310 struct sk_buff *skb = pkt->skb;
311
312 info->basechain = nft_base_chain(chain);
313 info->trace = true;
314 info->nf_trace = pkt->skb->nf_trace;
315 info->packet_dumped = false;
316
317 net_get_random_once(&trace_key, sizeof(trace_key));
318
319 info->skbid = (u32)siphash_3u32(hash32_ptr(skb),
320 skb_get_hash(skb),
321 skb->skb_iif,
322 &trace_key);
323 }
324