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1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * common LSM auditing functions
4  *
5  * Based on code written for SELinux by :
6  *			Stephen Smalley, <sds@tycho.nsa.gov>
7  * 			James Morris <jmorris@redhat.com>
8  * Author : Etienne Basset, <etienne.basset@ensta.org>
9  */
10 
11 #include <linux/types.h>
12 #include <linux/stddef.h>
13 #include <linux/kernel.h>
14 #include <linux/gfp.h>
15 #include <linux/fs.h>
16 #include <linux/init.h>
17 #include <net/sock.h>
18 #include <linux/un.h>
19 #include <net/af_unix.h>
20 #include <linux/audit.h>
21 #include <linux/ipv6.h>
22 #include <linux/ip.h>
23 #include <net/ip.h>
24 #include <net/ipv6.h>
25 #include <linux/tcp.h>
26 #include <linux/udp.h>
27 #include <linux/dccp.h>
28 #include <linux/sctp.h>
29 #include <linux/lsm_audit.h>
30 #include <linux/security.h>
31 
32 /**
33  * ipv4_skb_to_auditdata : fill auditdata from skb
34  * @skb : the skb
35  * @ad : the audit data to fill
36  * @proto : the layer 4 protocol
37  *
38  * return  0 on success
39  */
ipv4_skb_to_auditdata(struct sk_buff * skb,struct common_audit_data * ad,u8 * proto)40 int ipv4_skb_to_auditdata(struct sk_buff *skb,
41 		struct common_audit_data *ad, u8 *proto)
42 {
43 	int ret = 0;
44 	struct iphdr *ih;
45 
46 	ih = ip_hdr(skb);
47 	if (ih == NULL)
48 		return -EINVAL;
49 
50 	ad->u.net->v4info.saddr = ih->saddr;
51 	ad->u.net->v4info.daddr = ih->daddr;
52 
53 	if (proto)
54 		*proto = ih->protocol;
55 	/* non initial fragment */
56 	if (ntohs(ih->frag_off) & IP_OFFSET)
57 		return 0;
58 
59 	switch (ih->protocol) {
60 	case IPPROTO_TCP: {
61 		struct tcphdr *th = tcp_hdr(skb);
62 		if (th == NULL)
63 			break;
64 
65 		ad->u.net->sport = th->source;
66 		ad->u.net->dport = th->dest;
67 		break;
68 	}
69 	case IPPROTO_UDP: {
70 		struct udphdr *uh = udp_hdr(skb);
71 		if (uh == NULL)
72 			break;
73 
74 		ad->u.net->sport = uh->source;
75 		ad->u.net->dport = uh->dest;
76 		break;
77 	}
78 	case IPPROTO_DCCP: {
79 		struct dccp_hdr *dh = dccp_hdr(skb);
80 		if (dh == NULL)
81 			break;
82 
83 		ad->u.net->sport = dh->dccph_sport;
84 		ad->u.net->dport = dh->dccph_dport;
85 		break;
86 	}
87 	case IPPROTO_SCTP: {
88 		struct sctphdr *sh = sctp_hdr(skb);
89 		if (sh == NULL)
90 			break;
91 		ad->u.net->sport = sh->source;
92 		ad->u.net->dport = sh->dest;
93 		break;
94 	}
95 	default:
96 		ret = -EINVAL;
97 	}
98 	return ret;
99 }
100 #if IS_ENABLED(CONFIG_IPV6)
101 /**
102  * ipv6_skb_to_auditdata : fill auditdata from skb
103  * @skb : the skb
104  * @ad : the audit data to fill
105  * @proto : the layer 4 protocol
106  *
107  * return  0 on success
108  */
ipv6_skb_to_auditdata(struct sk_buff * skb,struct common_audit_data * ad,u8 * proto)109 int ipv6_skb_to_auditdata(struct sk_buff *skb,
110 		struct common_audit_data *ad, u8 *proto)
111 {
112 	int offset, ret = 0;
113 	struct ipv6hdr *ip6;
114 	u8 nexthdr;
115 	__be16 frag_off;
116 
117 	ip6 = ipv6_hdr(skb);
118 	if (ip6 == NULL)
119 		return -EINVAL;
120 	ad->u.net->v6info.saddr = ip6->saddr;
121 	ad->u.net->v6info.daddr = ip6->daddr;
122 	ret = 0;
123 	/* IPv6 can have several extension header before the Transport header
124 	 * skip them */
125 	offset = skb_network_offset(skb);
126 	offset += sizeof(*ip6);
127 	nexthdr = ip6->nexthdr;
128 	offset = ipv6_skip_exthdr(skb, offset, &nexthdr, &frag_off);
129 	if (offset < 0)
130 		return 0;
131 	if (proto)
132 		*proto = nexthdr;
133 	switch (nexthdr) {
134 	case IPPROTO_TCP: {
135 		struct tcphdr _tcph, *th;
136 
137 		th = skb_header_pointer(skb, offset, sizeof(_tcph), &_tcph);
138 		if (th == NULL)
139 			break;
140 
141 		ad->u.net->sport = th->source;
142 		ad->u.net->dport = th->dest;
143 		break;
144 	}
145 	case IPPROTO_UDP: {
146 		struct udphdr _udph, *uh;
147 
148 		uh = skb_header_pointer(skb, offset, sizeof(_udph), &_udph);
149 		if (uh == NULL)
150 			break;
151 
152 		ad->u.net->sport = uh->source;
153 		ad->u.net->dport = uh->dest;
154 		break;
155 	}
156 	case IPPROTO_DCCP: {
157 		struct dccp_hdr _dccph, *dh;
158 
159 		dh = skb_header_pointer(skb, offset, sizeof(_dccph), &_dccph);
160 		if (dh == NULL)
161 			break;
162 
163 		ad->u.net->sport = dh->dccph_sport;
164 		ad->u.net->dport = dh->dccph_dport;
165 		break;
166 	}
167 	case IPPROTO_SCTP: {
168 		struct sctphdr _sctph, *sh;
169 
170 		sh = skb_header_pointer(skb, offset, sizeof(_sctph), &_sctph);
171 		if (sh == NULL)
172 			break;
173 		ad->u.net->sport = sh->source;
174 		ad->u.net->dport = sh->dest;
175 		break;
176 	}
177 	default:
178 		ret = -EINVAL;
179 	}
180 	return ret;
181 }
182 #endif
183 
184 
print_ipv6_addr(struct audit_buffer * ab,struct in6_addr * addr,__be16 port,char * name1,char * name2)185 static inline void print_ipv6_addr(struct audit_buffer *ab,
186 				   struct in6_addr *addr, __be16 port,
187 				   char *name1, char *name2)
188 {
189 	if (!ipv6_addr_any(addr))
190 		audit_log_format(ab, " %s=%pI6c", name1, addr);
191 	if (port)
192 		audit_log_format(ab, " %s=%d", name2, ntohs(port));
193 }
194 
print_ipv4_addr(struct audit_buffer * ab,__be32 addr,__be16 port,char * name1,char * name2)195 static inline void print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
196 				   __be16 port, char *name1, char *name2)
197 {
198 	if (addr)
199 		audit_log_format(ab, " %s=%pI4", name1, &addr);
200 	if (port)
201 		audit_log_format(ab, " %s=%d", name2, ntohs(port));
202 }
203 
204 /**
205  * dump_common_audit_data - helper to dump common audit data
206  * @a : common audit data
207  *
208  */
dump_common_audit_data(struct audit_buffer * ab,struct common_audit_data * a)209 static void dump_common_audit_data(struct audit_buffer *ab,
210 				   struct common_audit_data *a)
211 {
212 	char comm[sizeof(current->comm)];
213 
214 	/*
215 	 * To keep stack sizes in check force programers to notice if they
216 	 * start making this union too large!  See struct lsm_network_audit
217 	 * as an example of how to deal with large data.
218 	 */
219 	BUILD_BUG_ON(sizeof(a->u) > sizeof(void *)*2);
220 
221 	audit_log_format(ab, " pid=%d comm=", task_tgid_nr(current));
222 	audit_log_untrustedstring(ab, memcpy(comm, current->comm, sizeof(comm)));
223 
224 	switch (a->type) {
225 	case LSM_AUDIT_DATA_NONE:
226 		return;
227 	case LSM_AUDIT_DATA_IPC:
228 		audit_log_format(ab, " key=%d ", a->u.ipc_id);
229 		break;
230 	case LSM_AUDIT_DATA_CAP:
231 		audit_log_format(ab, " capability=%d ", a->u.cap);
232 		break;
233 	case LSM_AUDIT_DATA_PATH: {
234 		struct inode *inode;
235 
236 		audit_log_d_path(ab, " path=", &a->u.path);
237 
238 		inode = d_backing_inode(a->u.path.dentry);
239 		if (inode) {
240 			audit_log_format(ab, " dev=");
241 			audit_log_untrustedstring(ab, inode->i_sb->s_id);
242 			audit_log_format(ab, " ino=%lu", inode->i_ino);
243 		}
244 		audit_getcwd();
245 		break;
246 	}
247 	case LSM_AUDIT_DATA_FILE: {
248 		struct inode *inode;
249 
250 		audit_log_d_path(ab, " path=", &a->u.file->f_path);
251 
252 		inode = file_inode(a->u.file);
253 		if (inode) {
254 			audit_log_format(ab, " dev=");
255 			audit_log_untrustedstring(ab, inode->i_sb->s_id);
256 			audit_log_format(ab, " ino=%lu", inode->i_ino);
257 		}
258 		audit_getcwd();
259 		break;
260 	}
261 	case LSM_AUDIT_DATA_IOCTL_OP: {
262 		struct inode *inode;
263 
264 		audit_log_d_path(ab, " path=", &a->u.op->path);
265 
266 		inode = a->u.op->path.dentry->d_inode;
267 		if (inode) {
268 			audit_log_format(ab, " dev=");
269 			audit_log_untrustedstring(ab, inode->i_sb->s_id);
270 			audit_log_format(ab, " ino=%lu", inode->i_ino);
271 		}
272 
273 		audit_log_format(ab, " ioctlcmd=0x%hx", a->u.op->cmd);
274 		audit_getcwd();
275 		break;
276 	}
277 	case LSM_AUDIT_DATA_DENTRY: {
278 		struct inode *inode;
279 
280 		audit_log_format(ab, " name=");
281 		spin_lock(&a->u.dentry->d_lock);
282 		audit_log_untrustedstring(ab, a->u.dentry->d_name.name);
283 		spin_unlock(&a->u.dentry->d_lock);
284 
285 		inode = d_backing_inode(a->u.dentry);
286 		if (inode) {
287 			audit_log_format(ab, " dev=");
288 			audit_log_untrustedstring(ab, inode->i_sb->s_id);
289 			audit_log_format(ab, " ino=%lu", inode->i_ino);
290 		}
291 		audit_getcwd();
292 		break;
293 	}
294 	case LSM_AUDIT_DATA_INODE: {
295 		struct dentry *dentry;
296 		struct inode *inode;
297 
298 		inode = a->u.inode;
299 		dentry = d_find_alias(inode);
300 		if (dentry) {
301 			audit_log_format(ab, " name=");
302 			spin_lock(&dentry->d_lock);
303 			audit_log_untrustedstring(ab, dentry->d_name.name);
304 			spin_unlock(&dentry->d_lock);
305 			dput(dentry);
306 		}
307 		audit_log_format(ab, " dev=");
308 		audit_log_untrustedstring(ab, inode->i_sb->s_id);
309 		audit_log_format(ab, " ino=%lu", inode->i_ino);
310 		audit_getcwd();
311 		break;
312 	}
313 	case LSM_AUDIT_DATA_TASK: {
314 		struct task_struct *tsk = a->u.tsk;
315 		if (tsk) {
316 			pid_t pid = task_tgid_nr(tsk);
317 			if (pid) {
318 				char comm[sizeof(tsk->comm)];
319 				audit_log_format(ab, " opid=%d ocomm=", pid);
320 				audit_log_untrustedstring(ab,
321 				    memcpy(comm, tsk->comm, sizeof(comm)));
322 			}
323 		}
324 		break;
325 	}
326 	case LSM_AUDIT_DATA_NET:
327 		if (a->u.net->sk) {
328 			struct sock *sk = a->u.net->sk;
329 			struct unix_sock *u;
330 			struct unix_address *addr;
331 			int len = 0;
332 			char *p = NULL;
333 
334 			switch (sk->sk_family) {
335 			case AF_INET: {
336 				struct inet_sock *inet = inet_sk(sk);
337 
338 				print_ipv4_addr(ab, inet->inet_rcv_saddr,
339 						inet->inet_sport,
340 						"laddr", "lport");
341 				print_ipv4_addr(ab, inet->inet_daddr,
342 						inet->inet_dport,
343 						"faddr", "fport");
344 				break;
345 			}
346 #if IS_ENABLED(CONFIG_IPV6)
347 			case AF_INET6: {
348 				struct inet_sock *inet = inet_sk(sk);
349 
350 				print_ipv6_addr(ab, &sk->sk_v6_rcv_saddr,
351 						inet->inet_sport,
352 						"laddr", "lport");
353 				print_ipv6_addr(ab, &sk->sk_v6_daddr,
354 						inet->inet_dport,
355 						"faddr", "fport");
356 				break;
357 			}
358 #endif
359 			case AF_UNIX:
360 				u = unix_sk(sk);
361 				addr = smp_load_acquire(&u->addr);
362 				if (!addr)
363 					break;
364 				if (u->path.dentry) {
365 					audit_log_d_path(ab, " path=", &u->path);
366 					break;
367 				}
368 				len = addr->len-sizeof(short);
369 				p = &addr->name->sun_path[0];
370 				audit_log_format(ab, " path=");
371 				if (*p)
372 					audit_log_untrustedstring(ab, p);
373 				else
374 					audit_log_n_hex(ab, p, len);
375 				break;
376 			}
377 		}
378 
379 		switch (a->u.net->family) {
380 		case AF_INET:
381 			print_ipv4_addr(ab, a->u.net->v4info.saddr,
382 					a->u.net->sport,
383 					"saddr", "src");
384 			print_ipv4_addr(ab, a->u.net->v4info.daddr,
385 					a->u.net->dport,
386 					"daddr", "dest");
387 			break;
388 		case AF_INET6:
389 			print_ipv6_addr(ab, &a->u.net->v6info.saddr,
390 					a->u.net->sport,
391 					"saddr", "src");
392 			print_ipv6_addr(ab, &a->u.net->v6info.daddr,
393 					a->u.net->dport,
394 					"daddr", "dest");
395 			break;
396 		}
397 		if (a->u.net->netif > 0) {
398 			struct net_device *dev;
399 
400 			/* NOTE: we always use init's namespace */
401 			dev = dev_get_by_index(&init_net, a->u.net->netif);
402 			if (dev) {
403 				audit_log_format(ab, " netif=%s", dev->name);
404 				dev_put(dev);
405 			}
406 		}
407 		break;
408 #ifdef CONFIG_KEYS
409 	case LSM_AUDIT_DATA_KEY:
410 		audit_log_format(ab, " key_serial=%u", a->u.key_struct.key);
411 		if (a->u.key_struct.key_desc) {
412 			audit_log_format(ab, " key_desc=");
413 			audit_log_untrustedstring(ab, a->u.key_struct.key_desc);
414 		}
415 		break;
416 #endif
417 	case LSM_AUDIT_DATA_KMOD:
418 		audit_log_format(ab, " kmod=");
419 		audit_log_untrustedstring(ab, a->u.kmod_name);
420 		break;
421 	case LSM_AUDIT_DATA_IBPKEY: {
422 		struct in6_addr sbn_pfx;
423 
424 		memset(&sbn_pfx.s6_addr, 0,
425 		       sizeof(sbn_pfx.s6_addr));
426 		memcpy(&sbn_pfx.s6_addr, &a->u.ibpkey->subnet_prefix,
427 		       sizeof(a->u.ibpkey->subnet_prefix));
428 		audit_log_format(ab, " pkey=0x%x subnet_prefix=%pI6c",
429 				 a->u.ibpkey->pkey, &sbn_pfx);
430 		break;
431 	}
432 	case LSM_AUDIT_DATA_IBENDPORT:
433 		audit_log_format(ab, " device=%s port_num=%u",
434 				 a->u.ibendport->dev_name,
435 				 a->u.ibendport->port);
436 		break;
437 	case LSM_AUDIT_DATA_LOCKDOWN:
438 		audit_log_format(ab, " lockdown_reason=\"%s\"",
439 				 lockdown_reasons[a->u.reason]);
440 		break;
441 	} /* switch (a->type) */
442 }
443 
444 /**
445  * common_lsm_audit - generic LSM auditing function
446  * @a:  auxiliary audit data
447  * @pre_audit: lsm-specific pre-audit callback
448  * @post_audit: lsm-specific post-audit callback
449  *
450  * setup the audit buffer for common security information
451  * uses callback to print LSM specific information
452  */
common_lsm_audit(struct common_audit_data * a,void (* pre_audit)(struct audit_buffer *,void *),void (* post_audit)(struct audit_buffer *,void *))453 void common_lsm_audit(struct common_audit_data *a,
454 	void (*pre_audit)(struct audit_buffer *, void *),
455 	void (*post_audit)(struct audit_buffer *, void *))
456 {
457 	struct audit_buffer *ab;
458 
459 	if (a == NULL)
460 		return;
461 	/* we use GFP_ATOMIC so we won't sleep */
462 	ab = audit_log_start(audit_context(), GFP_ATOMIC | __GFP_NOWARN,
463 			     AUDIT_AVC);
464 
465 	if (ab == NULL)
466 		return;
467 
468 	if (pre_audit)
469 		pre_audit(ab, a);
470 
471 	dump_common_audit_data(ab, a);
472 
473 	if (post_audit)
474 		post_audit(ab, a);
475 
476 	audit_log_end(ab);
477 }
478