security/lsm_audit.c

   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_DENTRY: {
 249                 struct inode *inode;
 250
 251                 audit_log_format(ab, " name=");
 252                 audit_log_untrustedstring(ab, a->u.dentry->d_name.name);
 253
 254                 inode = d_backing_inode(a->u.dentry);
 255                 if (inode) {
 256                         audit_log_format(ab, " dev=");
 257                         audit_log_untrustedstring(ab, inode->i_sb->s_id);
 258                         audit_log_format(ab, " ino=%lu", inode->i_ino);
 259                 }
 260                 break;
 261         }
 262         case LSM_AUDIT_DATA_INODE: {
 263                 struct dentry *dentry;
 264                 struct inode *inode;
 265
 266                 inode = a->u.inode;
 267                 dentry = d_find_alias(inode);
 268                 if (dentry) {
 269                         audit_log_format(ab, " name=");
 270                         audit_log_untrustedstring(ab,
 271                                          dentry->d_name.name);
 272                         dput(dentry);
 273                 }
 274                 audit_log_format(ab, " dev=");
 275                 audit_log_untrustedstring(ab, inode->i_sb->s_id);
 276                 audit_log_format(ab, " ino=%lu", inode->i_ino);
 277                 break;
 278         }
 279         case LSM_AUDIT_DATA_TASK: {
 280                 struct task_struct *tsk = a->u.tsk;
 281                 if (tsk) {
 282                         pid_t pid = task_pid_nr(tsk);
 283                         if (pid) {
 284                                 char comm[sizeof(tsk->comm)];
 285                                 audit_log_format(ab, " pid=%d comm=", pid);
 286                                 audit_log_untrustedstring(ab,
 287                                     memcpy(comm, tsk->comm, sizeof(comm)));
 288                         }
 289                 }
 290                 break;
 291         }
 292         case LSM_AUDIT_DATA_NET:
 293                 if (a->u.net->sk) {
 294                         struct sock *sk = a->u.net->sk;
 295                         struct unix_sock *u;
 296                         int len = 0;
 297                         char *p = NULL;
 298
 299                         switch (sk->sk_family) {
 300                         case AF_INET: {
 301                                 struct inet_sock *inet = inet_sk(sk);
 302
 303                                 print_ipv4_addr(ab, inet->inet_rcv_saddr,
 304                                                 inet->inet_sport,
 305                                                 "laddr", "lport");
 306                                 print_ipv4_addr(ab, inet->inet_daddr,
 307                                                 inet->inet_dport,
 308                                                 "faddr", "fport");
 309                                 break;
 310                         }
 311 #if IS_ENABLED(CONFIG_IPV6)
 312                         case AF_INET6: {
 313                                 struct inet_sock *inet = inet_sk(sk);
 314
 315                                 print_ipv6_addr(ab, &sk->sk_v6_rcv_saddr,
 316                                                 inet->inet_sport,
 317                                                 "laddr", "lport");
 318                                 print_ipv6_addr(ab, &sk->sk_v6_daddr,
 319                                                 inet->inet_dport,
 320                                                 "faddr", "fport");
 321                                 break;
 322                         }
 323 #endif
 324                         case AF_UNIX:
 325                                 u = unix_sk(sk);
 326                                 if (u->path.dentry) {
 327                                         audit_log_d_path(ab, " path=", &u->path);
 328                                         break;
 329                                 }
 330                                 if (!u->addr)
 331                                         break;
 332                                 len = u->addr->len-sizeof(short);
 333                                 p = &u->addr->name->sun_path[0];
 334                                 audit_log_format(ab, " path=");
 335                                 if (*p)
 336                                         audit_log_untrustedstring(ab, p);
 337                                 else
 338                                         audit_log_n_hex(ab, p, len);
 339                                 break;
 340                         }
 341                 }
 342
 343                 switch (a->u.net->family) {
 344                 case AF_INET:
 345                         print_ipv4_addr(ab, a->u.net->v4info.saddr,
 346                                         a->u.net->sport,
 347                                         "saddr", "src");
 348                         print_ipv4_addr(ab, a->u.net->v4info.daddr,
 349                                         a->u.net->dport,
 350                                         "daddr", "dest");
 351                         break;
 352                 case AF_INET6:
 353                         print_ipv6_addr(ab, &a->u.net->v6info.saddr,
 354                                         a->u.net->sport,
 355                                         "saddr", "src");
 356                         print_ipv6_addr(ab, &a->u.net->v6info.daddr,
 357                                         a->u.net->dport,
 358                                         "daddr", "dest");
 359                         break;
 360                 }
 361                 if (a->u.net->netif > 0) {
 362                         struct net_device *dev;
 363
 364                         /* NOTE: we always use init's namespace */
 365                         dev = dev_get_by_index(&init_net, a->u.net->netif);
 366                         if (dev) {
 367                                 audit_log_format(ab, " netif=%s", dev->name);
 368                                 dev_put(dev);
 369                         }
 370                 }
 371                 break;
 372 #ifdef CONFIG_KEYS
 373         case LSM_AUDIT_DATA_KEY:
 374                 audit_log_format(ab, " key_serial=%u", a->u.key_struct.key);
 375                 if (a->u.key_struct.key_desc) {
 376                         audit_log_format(ab, " key_desc=");
 377                         audit_log_untrustedstring(ab, a->u.key_struct.key_desc);
 378                 }
 379                 break;
 380 #endif
 381         case LSM_AUDIT_DATA_KMOD:
 382                 audit_log_format(ab, " kmod=");
 383                 audit_log_untrustedstring(ab, a->u.kmod_name);
 384                 break;
 385         } /* switch (a->type) */
 386 }
 387
 388 /**
 389  * common_lsm_audit - generic LSM auditing function
 390  * @a:  auxiliary audit data
 391  * @pre_audit: lsm-specific pre-audit callback
 392  * @post_audit: lsm-specific post-audit callback
 393  *
 394  * setup the audit buffer for common security information
 395  * uses callback to print LSM specific information
 396  */
 397 void common_lsm_audit(struct common_audit_data *a,
 398         void (*pre_audit)(struct audit_buffer *, void *),
 399         void (*post_audit)(struct audit_buffer *, void *))
 400 {
 401         struct audit_buffer *ab;
 402
 403         if (a == NULL)
 404                 return;
 405         /* we use GFP_ATOMIC so we won't sleep */
 406         ab = audit_log_start(current->audit_context, GFP_ATOMIC | __GFP_NOWARN,
 407                              AUDIT_AVC);
 408
 409         if (ab == NULL)
 410                 return;
 411
 412         if (pre_audit)
 413                 pre_audit(ab, a);
 414
 415         dump_common_audit_data(ab, a);
 416
 417         if (post_audit)
 418                 post_audit(ab, a);
 419
 420         audit_log_end(ab);
 421 }