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TOMOYO Linux Cross Reference
Linux/security/lsm_audit.c

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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  */
 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  */
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 
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 
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  */
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                 audit_log_untrustedstring(ab, a->u.dentry->d_name.name);
282 
283                 inode = d_backing_inode(a->u.dentry);
284                 if (inode) {
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                 }
289                 audit_getcwd();
290                 break;
291         }
292         case LSM_AUDIT_DATA_INODE: {
293                 struct dentry *dentry;
294                 struct inode *inode;
295 
296                 inode = a->u.inode;
297                 dentry = d_find_alias(inode);
298                 if (dentry) {
299                         audit_log_format(ab, " name=");
300                         audit_log_untrustedstring(ab,
301                                          dentry->d_name.name);
302                         dput(dentry);
303                 }
304                 audit_log_format(ab, " dev=");
305                 audit_log_untrustedstring(ab, inode->i_sb->s_id);
306                 audit_log_format(ab, " ino=%lu", inode->i_ino);
307                 audit_getcwd();
308                 break;
309         }
310         case LSM_AUDIT_DATA_TASK: {
311                 struct task_struct *tsk = a->u.tsk;
312                 if (tsk) {
313                         pid_t pid = task_tgid_nr(tsk);
314                         if (pid) {
315                                 char comm[sizeof(tsk->comm)];
316                                 audit_log_format(ab, " opid=%d ocomm=", pid);
317                                 audit_log_untrustedstring(ab,
318                                     memcpy(comm, tsk->comm, sizeof(comm)));
319                         }
320                 }
321                 break;
322         }
323         case LSM_AUDIT_DATA_NET:
324                 if (a->u.net->sk) {
325                         struct sock *sk = a->u.net->sk;
326                         struct unix_sock *u;
327                         struct unix_address *addr;
328                         int len = 0;
329                         char *p = NULL;
330 
331                         switch (sk->sk_family) {
332                         case AF_INET: {
333                                 struct inet_sock *inet = inet_sk(sk);
334 
335                                 print_ipv4_addr(ab, inet->inet_rcv_saddr,
336                                                 inet->inet_sport,
337                                                 "laddr", "lport");
338                                 print_ipv4_addr(ab, inet->inet_daddr,
339                                                 inet->inet_dport,
340                                                 "faddr", "fport");
341                                 break;
342                         }
343 #if IS_ENABLED(CONFIG_IPV6)
344                         case AF_INET6: {
345                                 struct inet_sock *inet = inet_sk(sk);
346 
347                                 print_ipv6_addr(ab, &sk->sk_v6_rcv_saddr,
348                                                 inet->inet_sport,
349                                                 "laddr", "lport");
350                                 print_ipv6_addr(ab, &sk->sk_v6_daddr,
351                                                 inet->inet_dport,
352                                                 "faddr", "fport");
353                                 break;
354                         }
355 #endif
356                         case AF_UNIX:
357                                 u = unix_sk(sk);
358                                 addr = smp_load_acquire(&u->addr);
359                                 if (!addr)
360                                         break;
361                                 if (u->path.dentry) {
362                                         audit_log_d_path(ab, " path=", &u->path);
363                                         break;
364                                 }
365                                 len = addr->len-sizeof(short);
366                                 p = &addr->name->sun_path[0];
367                                 audit_log_format(ab, " path=");
368                                 if (*p)
369                                         audit_log_untrustedstring(ab, p);
370                                 else
371                                         audit_log_n_hex(ab, p, len);
372                                 break;
373                         }
374                 }
375 
376                 switch (a->u.net->family) {
377                 case AF_INET:
378                         print_ipv4_addr(ab, a->u.net->v4info.saddr,
379                                         a->u.net->sport,
380                                         "saddr", "src");
381                         print_ipv4_addr(ab, a->u.net->v4info.daddr,
382                                         a->u.net->dport,
383                                         "daddr", "dest");
384                         break;
385                 case AF_INET6:
386                         print_ipv6_addr(ab, &a->u.net->v6info.saddr,
387                                         a->u.net->sport,
388                                         "saddr", "src");
389                         print_ipv6_addr(ab, &a->u.net->v6info.daddr,
390                                         a->u.net->dport,
391                                         "daddr", "dest");
392                         break;
393                 }
394                 if (a->u.net->netif > 0) {
395                         struct net_device *dev;
396 
397                         /* NOTE: we always use init's namespace */
398                         dev = dev_get_by_index(&init_net, a->u.net->netif);
399                         if (dev) {
400                                 audit_log_format(ab, " netif=%s", dev->name);
401                                 dev_put(dev);
402                         }
403                 }
404                 break;
405 #ifdef CONFIG_KEYS
406         case LSM_AUDIT_DATA_KEY:
407                 audit_log_format(ab, " key_serial=%u", a->u.key_struct.key);
408                 if (a->u.key_struct.key_desc) {
409                         audit_log_format(ab, " key_desc=");
410                         audit_log_untrustedstring(ab, a->u.key_struct.key_desc);
411                 }
412                 break;
413 #endif
414         case LSM_AUDIT_DATA_KMOD:
415                 audit_log_format(ab, " kmod=");
416                 audit_log_untrustedstring(ab, a->u.kmod_name);
417                 break;
418         case LSM_AUDIT_DATA_IBPKEY: {
419                 struct in6_addr sbn_pfx;
420 
421                 memset(&sbn_pfx.s6_addr, 0,
422                        sizeof(sbn_pfx.s6_addr));
423                 memcpy(&sbn_pfx.s6_addr, &a->u.ibpkey->subnet_prefix,
424                        sizeof(a->u.ibpkey->subnet_prefix));
425                 audit_log_format(ab, " pkey=0x%x subnet_prefix=%pI6c",
426                                  a->u.ibpkey->pkey, &sbn_pfx);
427                 break;
428         }
429         case LSM_AUDIT_DATA_IBENDPORT:
430                 audit_log_format(ab, " device=%s port_num=%u",
431                                  a->u.ibendport->dev_name,
432                                  a->u.ibendport->port);
433                 break;
434         case LSM_AUDIT_DATA_LOCKDOWN:
435                 audit_log_format(ab, " lockdown_reason=\"%s\"",
436                                  lockdown_reasons[a->u.reason]);
437                 break;
438         } /* switch (a->type) */
439 }
440 
441 /**
442  * common_lsm_audit - generic LSM auditing function
443  * @a:  auxiliary audit data
444  * @pre_audit: lsm-specific pre-audit callback
445  * @post_audit: lsm-specific post-audit callback
446  *
447  * setup the audit buffer for common security information
448  * uses callback to print LSM specific information
449  */
450 void common_lsm_audit(struct common_audit_data *a,
451         void (*pre_audit)(struct audit_buffer *, void *),
452         void (*post_audit)(struct audit_buffer *, void *))
453 {
454         struct audit_buffer *ab;
455 
456         if (a == NULL)
457                 return;
458         /* we use GFP_ATOMIC so we won't sleep */
459         ab = audit_log_start(audit_context(), GFP_ATOMIC | __GFP_NOWARN,
460                              AUDIT_AVC);
461 
462         if (ab == NULL)
463                 return;
464 
465         if (pre_audit)
466                 pre_audit(ab, a);
467 
468         dump_common_audit_data(ab, a);
469 
470         if (post_audit)
471                 post_audit(ab, a);
472 
473         audit_log_end(ab);
474 }
475 

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