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