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