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Linux/security/lsm_audit.c

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  1 /*
  2  * common LSM auditing functions
  3  *
  4  * Based on code written for SELinux by :
  5  *                      Stephen Smalley, <sds@epoch.ncsc.mil>
  6  *                      James Morris <jmorris@redhat.com>
  7  * Author : Etienne Basset, <etienne.basset@ensta.org>
  8  *
  9  * This program is free software; you can redistribute it and/or modify
 10  * it under the terms of the GNU General Public License version 2,
 11  * as published by the Free Software Foundation.
 12  */
 13 
 14 #include <linux/types.h>
 15 #include <linux/stddef.h>
 16 #include <linux/kernel.h>
 17 #include <linux/gfp.h>
 18 #include <linux/fs.h>
 19 #include <linux/init.h>
 20 #include <net/sock.h>
 21 #include <linux/un.h>
 22 #include <net/af_unix.h>
 23 #include <linux/audit.h>
 24 #include <linux/ipv6.h>
 25 #include <linux/ip.h>
 26 #include <net/ip.h>
 27 #include <net/ipv6.h>
 28 #include <linux/tcp.h>
 29 #include <linux/udp.h>
 30 #include <linux/dccp.h>
 31 #include <linux/sctp.h>
 32 #include <linux/lsm_audit.h>
 33 
 34 /**
 35  * ipv4_skb_to_auditdata : fill auditdata from skb
 36  * @skb : the skb
 37  * @ad : the audit data to fill
 38  * @proto : the layer 4 protocol
 39  *
 40  * return  0 on success
 41  */
 42 int ipv4_skb_to_auditdata(struct sk_buff *skb,
 43                 struct common_audit_data *ad, u8 *proto)
 44 {
 45         int ret = 0;
 46         struct iphdr *ih;
 47 
 48         ih = ip_hdr(skb);
 49         if (ih == NULL)
 50                 return -EINVAL;
 51 
 52         ad->u.net->v4info.saddr = ih->saddr;
 53         ad->u.net->v4info.daddr = ih->daddr;
 54 
 55         if (proto)
 56                 *proto = ih->protocol;
 57         /* non initial fragment */
 58         if (ntohs(ih->frag_off) & IP_OFFSET)
 59                 return 0;
 60 
 61         switch (ih->protocol) {
 62         case IPPROTO_TCP: {
 63                 struct tcphdr *th = tcp_hdr(skb);
 64                 if (th == NULL)
 65                         break;
 66 
 67                 ad->u.net->sport = th->source;
 68                 ad->u.net->dport = th->dest;
 69                 break;
 70         }
 71         case IPPROTO_UDP: {
 72                 struct udphdr *uh = udp_hdr(skb);
 73                 if (uh == NULL)
 74                         break;
 75 
 76                 ad->u.net->sport = uh->source;
 77                 ad->u.net->dport = uh->dest;
 78                 break;
 79         }
 80         case IPPROTO_DCCP: {
 81                 struct dccp_hdr *dh = dccp_hdr(skb);
 82                 if (dh == NULL)
 83                         break;
 84 
 85                 ad->u.net->sport = dh->dccph_sport;
 86                 ad->u.net->dport = dh->dccph_dport;
 87                 break;
 88         }
 89         case IPPROTO_SCTP: {
 90                 struct sctphdr *sh = sctp_hdr(skb);
 91                 if (sh == NULL)
 92                         break;
 93                 ad->u.net->sport = sh->source;
 94                 ad->u.net->dport = sh->dest;
 95                 break;
 96         }
 97         default:
 98                 ret = -EINVAL;
 99         }
100         return ret;
101 }
102 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
103 /**
104  * ipv6_skb_to_auditdata : fill auditdata from skb
105  * @skb : the skb
106  * @ad : the audit data to fill
107  * @proto : the layer 4 protocol
108  *
109  * return  0 on success
110  */
111 int ipv6_skb_to_auditdata(struct sk_buff *skb,
112                 struct common_audit_data *ad, u8 *proto)
113 {
114         int offset, ret = 0;
115         struct ipv6hdr *ip6;
116         u8 nexthdr;
117         __be16 frag_off;
118 
119         ip6 = ipv6_hdr(skb);
120         if (ip6 == NULL)
121                 return -EINVAL;
122         ad->u.net->v6info.saddr = ip6->saddr;
123         ad->u.net->v6info.daddr = ip6->daddr;
124         ret = 0;
125         /* IPv6 can have several extension header before the Transport header
126          * skip them */
127         offset = skb_network_offset(skb);
128         offset += sizeof(*ip6);
129         nexthdr = ip6->nexthdr;
130         offset = ipv6_skip_exthdr(skb, offset, &nexthdr, &frag_off);
131         if (offset < 0)
132                 return 0;
133         if (proto)
134                 *proto = nexthdr;
135         switch (nexthdr) {
136         case IPPROTO_TCP: {
137                 struct tcphdr _tcph, *th;
138 
139                 th = skb_header_pointer(skb, offset, sizeof(_tcph), &_tcph);
140                 if (th == NULL)
141                         break;
142 
143                 ad->u.net->sport = th->source;
144                 ad->u.net->dport = th->dest;
145                 break;
146         }
147         case IPPROTO_UDP: {
148                 struct udphdr _udph, *uh;
149 
150                 uh = skb_header_pointer(skb, offset, sizeof(_udph), &_udph);
151                 if (uh == NULL)
152                         break;
153 
154                 ad->u.net->sport = uh->source;
155                 ad->u.net->dport = uh->dest;
156                 break;
157         }
158         case IPPROTO_DCCP: {
159                 struct dccp_hdr _dccph, *dh;
160 
161                 dh = skb_header_pointer(skb, offset, sizeof(_dccph), &_dccph);
162                 if (dh == NULL)
163                         break;
164 
165                 ad->u.net->sport = dh->dccph_sport;
166                 ad->u.net->dport = dh->dccph_dport;
167                 break;
168         }
169         case IPPROTO_SCTP: {
170                 struct sctphdr _sctph, *sh;
171 
172                 sh = skb_header_pointer(skb, offset, sizeof(_sctph), &_sctph);
173                 if (sh == NULL)
174                         break;
175                 ad->u.net->sport = sh->source;
176                 ad->u.net->dport = sh->dest;
177                 break;
178         }
179         default:
180                 ret = -EINVAL;
181         }
182         return ret;
183 }
184 #endif
185 
186 
187 static inline void print_ipv6_addr(struct audit_buffer *ab,
188                                    struct in6_addr *addr, __be16 port,
189                                    char *name1, char *name2)
190 {
191         if (!ipv6_addr_any(addr))
192                 audit_log_format(ab, " %s=%pI6c", name1, addr);
193         if (port)
194                 audit_log_format(ab, " %s=%d", name2, ntohs(port));
195 }
196 
197 static inline void print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
198                                    __be16 port, char *name1, char *name2)
199 {
200         if (addr)
201                 audit_log_format(ab, " %s=%pI4", name1, &addr);
202         if (port)
203                 audit_log_format(ab, " %s=%d", name2, ntohs(port));
204 }
205 
206 /**
207  * dump_common_audit_data - helper to dump common audit data
208  * @a : common audit data
209  *
210  */
211 static void dump_common_audit_data(struct audit_buffer *ab,
212                                    struct common_audit_data *a)
213 {
214         char comm[sizeof(current->comm)];
215 
216         /*
217          * To keep stack sizes in check force programers to notice if they
218          * start making this union too large!  See struct lsm_network_audit
219          * as an example of how to deal with large data.
220          */
221         BUILD_BUG_ON(sizeof(a->u) > sizeof(void *)*2);
222 
223         audit_log_format(ab, " pid=%d comm=", task_pid_nr(current));
224         audit_log_untrustedstring(ab, memcpy(comm, current->comm, sizeof(comm)));
225 
226         switch (a->type) {
227         case LSM_AUDIT_DATA_NONE:
228                 return;
229         case LSM_AUDIT_DATA_IPC:
230                 audit_log_format(ab, " key=%d ", a->u.ipc_id);
231                 break;
232         case LSM_AUDIT_DATA_CAP:
233                 audit_log_format(ab, " capability=%d ", a->u.cap);
234                 break;
235         case LSM_AUDIT_DATA_PATH: {
236                 struct inode *inode;
237 
238                 audit_log_d_path(ab, " path=", &a->u.path);
239 
240                 inode = d_backing_inode(a->u.path.dentry);
241                 if (inode) {
242                         audit_log_format(ab, " dev=");
243                         audit_log_untrustedstring(ab, inode->i_sb->s_id);
244                         audit_log_format(ab, " ino=%lu", inode->i_ino);
245                 }
246                 break;
247         }
248         case LSM_AUDIT_DATA_IOCTL_OP: {
249                 struct inode *inode;
250 
251                 audit_log_d_path(ab, " path=", &a->u.op->path);
252 
253                 inode = a->u.op->path.dentry->d_inode;
254                 if (inode) {
255                         audit_log_format(ab, " dev=");
256                         audit_log_untrustedstring(ab, inode->i_sb->s_id);
257                         audit_log_format(ab, " ino=%lu", inode->i_ino);
258                 }
259 
260                 audit_log_format(ab, " ioctlcmd=%hx", a->u.op->cmd);
261                 break;
262         }
263         case LSM_AUDIT_DATA_DENTRY: {
264                 struct inode *inode;
265 
266                 audit_log_format(ab, " name=");
267                 audit_log_untrustedstring(ab, a->u.dentry->d_name.name);
268 
269                 inode = d_backing_inode(a->u.dentry);
270                 if (inode) {
271                         audit_log_format(ab, " dev=");
272                         audit_log_untrustedstring(ab, inode->i_sb->s_id);
273                         audit_log_format(ab, " ino=%lu", inode->i_ino);
274                 }
275                 break;
276         }
277         case LSM_AUDIT_DATA_INODE: {
278                 struct dentry *dentry;
279                 struct inode *inode;
280 
281                 inode = a->u.inode;
282                 dentry = d_find_alias(inode);
283                 if (dentry) {
284                         audit_log_format(ab, " name=");
285                         audit_log_untrustedstring(ab,
286                                          dentry->d_name.name);
287                         dput(dentry);
288                 }
289                 audit_log_format(ab, " dev=");
290                 audit_log_untrustedstring(ab, inode->i_sb->s_id);
291                 audit_log_format(ab, " ino=%lu", inode->i_ino);
292                 break;
293         }
294         case LSM_AUDIT_DATA_TASK: {
295                 struct task_struct *tsk = a->u.tsk;
296                 if (tsk) {
297                         pid_t pid = task_pid_nr(tsk);
298                         if (pid) {
299                                 char comm[sizeof(tsk->comm)];
300                                 audit_log_format(ab, " opid=%d ocomm=", pid);
301                                 audit_log_untrustedstring(ab,
302                                     memcpy(comm, tsk->comm, sizeof(comm)));
303                         }
304                 }
305                 break;
306         }
307         case LSM_AUDIT_DATA_NET:
308                 if (a->u.net->sk) {
309                         struct sock *sk = a->u.net->sk;
310                         struct unix_sock *u;
311                         int len = 0;
312                         char *p = NULL;
313 
314                         switch (sk->sk_family) {
315                         case AF_INET: {
316                                 struct inet_sock *inet = inet_sk(sk);
317 
318                                 print_ipv4_addr(ab, inet->inet_rcv_saddr,
319                                                 inet->inet_sport,
320                                                 "laddr", "lport");
321                                 print_ipv4_addr(ab, inet->inet_daddr,
322                                                 inet->inet_dport,
323                                                 "faddr", "fport");
324                                 break;
325                         }
326 #if IS_ENABLED(CONFIG_IPV6)
327                         case AF_INET6: {
328                                 struct inet_sock *inet = inet_sk(sk);
329 
330                                 print_ipv6_addr(ab, &sk->sk_v6_rcv_saddr,
331                                                 inet->inet_sport,
332                                                 "laddr", "lport");
333                                 print_ipv6_addr(ab, &sk->sk_v6_daddr,
334                                                 inet->inet_dport,
335                                                 "faddr", "fport");
336                                 break;
337                         }
338 #endif
339                         case AF_UNIX:
340                                 u = unix_sk(sk);
341                                 if (u->path.dentry) {
342                                         audit_log_d_path(ab, " path=", &u->path);
343                                         break;
344                                 }
345                                 if (!u->addr)
346                                         break;
347                                 len = u->addr->len-sizeof(short);
348                                 p = &u->addr->name->sun_path[0];
349                                 audit_log_format(ab, " path=");
350                                 if (*p)
351                                         audit_log_untrustedstring(ab, p);
352                                 else
353                                         audit_log_n_hex(ab, p, len);
354                                 break;
355                         }
356                 }
357 
358                 switch (a->u.net->family) {
359                 case AF_INET:
360                         print_ipv4_addr(ab, a->u.net->v4info.saddr,
361                                         a->u.net->sport,
362                                         "saddr", "src");
363                         print_ipv4_addr(ab, a->u.net->v4info.daddr,
364                                         a->u.net->dport,
365                                         "daddr", "dest");
366                         break;
367                 case AF_INET6:
368                         print_ipv6_addr(ab, &a->u.net->v6info.saddr,
369                                         a->u.net->sport,
370                                         "saddr", "src");
371                         print_ipv6_addr(ab, &a->u.net->v6info.daddr,
372                                         a->u.net->dport,
373                                         "daddr", "dest");
374                         break;
375                 }
376                 if (a->u.net->netif > 0) {
377                         struct net_device *dev;
378 
379                         /* NOTE: we always use init's namespace */
380                         dev = dev_get_by_index(&init_net, a->u.net->netif);
381                         if (dev) {
382                                 audit_log_format(ab, " netif=%s", dev->name);
383                                 dev_put(dev);
384                         }
385                 }
386                 break;
387 #ifdef CONFIG_KEYS
388         case LSM_AUDIT_DATA_KEY:
389                 audit_log_format(ab, " key_serial=%u", a->u.key_struct.key);
390                 if (a->u.key_struct.key_desc) {
391                         audit_log_format(ab, " key_desc=");
392                         audit_log_untrustedstring(ab, a->u.key_struct.key_desc);
393                 }
394                 break;
395 #endif
396         case LSM_AUDIT_DATA_KMOD:
397                 audit_log_format(ab, " kmod=");
398                 audit_log_untrustedstring(ab, a->u.kmod_name);
399                 break;
400         } /* switch (a->type) */
401 }
402 
403 /**
404  * common_lsm_audit - generic LSM auditing function
405  * @a:  auxiliary audit data
406  * @pre_audit: lsm-specific pre-audit callback
407  * @post_audit: lsm-specific post-audit callback
408  *
409  * setup the audit buffer for common security information
410  * uses callback to print LSM specific information
411  */
412 void common_lsm_audit(struct common_audit_data *a,
413         void (*pre_audit)(struct audit_buffer *, void *),
414         void (*post_audit)(struct audit_buffer *, void *))
415 {
416         struct audit_buffer *ab;
417 
418         if (a == NULL)
419                 return;
420         /* we use GFP_ATOMIC so we won't sleep */
421         ab = audit_log_start(current->audit_context, GFP_ATOMIC | __GFP_NOWARN,
422                              AUDIT_AVC);
423 
424         if (ab == NULL)
425                 return;
426 
427         if (pre_audit)
428                 pre_audit(ab, a);
429 
430         dump_common_audit_data(ab, a);
431 
432         if (post_audit)
433                 post_audit(ab, a);
434 
435         audit_log_end(ab);
436 }
437 

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