lsm_audit.c 11 KB

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