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
 118         ip6 = ipv6_hdr(skb);
 119         if (ip6 == NULL)
 120                 return -EINVAL;
 121         ipv6_addr_copy(&ad->u.net.v6info.saddr, &ip6->saddr);
 122         ipv6_addr_copy(&ad->u.net.v6info.daddr, &ip6->daddr);
 123         ret = 0;
 124         /* IPv6 can have several extension header before the Transport header
 125          * skip them */
 126         offset = skb_network_offset(skb);
 127         offset += sizeof(*ip6);
 128         nexthdr = ip6->nexthdr;
 129         offset = ipv6_skip_exthdr(skb, offset, &nexthdr);
 130         if (offset < 0)
 131                 return 0;
 132         if (proto)
 133                 *proto = nexthdr;
 134         switch (nexthdr) {
 135         case IPPROTO_TCP: {
 136                 struct tcphdr _tcph, *th;
 137
 138                 th = skb_header_pointer(skb, offset, sizeof(_tcph), &_tcph);
 139                 if (th == NULL)
 140                         break;
 141
 142                 ad->u.net.sport = th->source;
 143                 ad->u.net.dport = th->dest;
 144                 break;
 145         }
 146         case IPPROTO_UDP: {
 147                 struct udphdr _udph, *uh;
 148
 149                 uh = skb_header_pointer(skb, offset, sizeof(_udph), &_udph);
 150                 if (uh == NULL)
 151                         break;
 152
 153                 ad->u.net.sport = uh->source;
 154                 ad->u.net.dport = uh->dest;
 155                 break;
 156         }
 157         case IPPROTO_DCCP: {
 158                 struct dccp_hdr _dccph, *dh;
 159
 160                 dh = skb_header_pointer(skb, offset, sizeof(_dccph), &_dccph);
 161                 if (dh == NULL)
 162                         break;
 163
 164                 ad->u.net.sport = dh->dccph_sport;
 165                 ad->u.net.dport = dh->dccph_dport;
 166                 break;
 167         }
 168         case IPPROTO_SCTP: {
 169                 struct sctphdr _sctph, *sh;
 170
 171                 sh = skb_header_pointer(skb, offset, sizeof(_sctph), &_sctph);
 172                 if (sh == NULL)
 173                         break;
 174                 ad->u.net.sport = sh->source;
 175                 ad->u.net.dport = sh->dest;
 176                 break;
 177         }
 178         default:
 179                 ret = -EINVAL;
 180         }
 181         return ret;
 182 }
 183 #endif
 184
 185
 186 static inline void print_ipv6_addr(struct audit_buffer *ab,
 187                                    struct in6_addr *addr, __be16 port,
 188                                    char *name1, char *name2)
 189 {
 190         if (!ipv6_addr_any(addr))
 191                 audit_log_format(ab, " %s=%pI6c", name1, addr);
 192         if (port)
 193                 audit_log_format(ab, " %s=%d", name2, ntohs(port));
 194 }
 195
 196 static inline void print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
 197                                    __be16 port, char *name1, char *name2)
 198 {
 199         if (addr)
 200                 audit_log_format(ab, " %s=%pI4", name1, &addr);
 201         if (port)
 202                 audit_log_format(ab, " %s=%d", name2, ntohs(port));
 203 }
 204
 205 /**
 206  * dump_common_audit_data - helper to dump common audit data
 207  * @a : common audit data
 208  *
 209  */
 210 static void dump_common_audit_data(struct audit_buffer *ab,
 211                                    struct common_audit_data *a)
 212 {
 213         struct task_struct *tsk = current;
 214
 215         if (a->tsk)
 216                 tsk = a->tsk;
 217         if (tsk && tsk->pid) {
 218                 audit_log_format(ab, " pid=%d comm=", tsk->pid);
 219                 audit_log_untrustedstring(ab, tsk->comm);
 220         }
 221
 222         switch (a->type) {
 223         case LSM_AUDIT_DATA_NONE:
 224                 return;
 225         case LSM_AUDIT_DATA_IPC:
 226                 audit_log_format(ab, " key=%d ", a->u.ipc_id);
 227                 break;
 228         case LSM_AUDIT_DATA_CAP:
 229                 audit_log_format(ab, " capability=%d ", a->u.cap);
 230                 break;
 231         case LSM_AUDIT_DATA_PATH: {
 232                 struct inode *inode;
 233
 234                 audit_log_d_path(ab, "path=", &a->u.path);
 235
 236                 inode = a->u.path.dentry->d_inode;
 237                 if (inode)
 238                         audit_log_format(ab, " dev=%s ino=%lu",
 239                                         inode->i_sb->s_id,
 240                                         inode->i_ino);
 241                 break;
 242         }
 243         case LSM_AUDIT_DATA_DENTRY: {
 244                 struct inode *inode;
 245
 246                 audit_log_format(ab, " name=");
 247                 audit_log_untrustedstring(ab, a->u.dentry->d_name.name);
 248
 249                 inode = a->u.dentry->d_inode;
 250                 if (inode)
 251                         audit_log_format(ab, " dev=%s ino=%lu",
 252                                         inode->i_sb->s_id,
 253                                         inode->i_ino);
 254                 break;
 255         }
 256         case LSM_AUDIT_DATA_INODE: {
 257                 struct dentry *dentry;
 258                 struct inode *inode;
 259
 260                 inode = a->u.inode;
 261                 dentry = d_find_alias(inode);
 262                 if (dentry) {
 263                         audit_log_format(ab, " name=");
 264                         audit_log_untrustedstring(ab,
 265                                          dentry->d_name.name);
 266                         dput(dentry);
 267                 }
 268                 audit_log_format(ab, " dev=%s ino=%lu", inode->i_sb->s_id,
 269                                  inode->i_ino);
 270                 break;
 271         }
 272         case LSM_AUDIT_DATA_TASK:
 273                 tsk = a->u.tsk;
 274                 if (tsk && tsk->pid) {
 275                         audit_log_format(ab, " pid=%d comm=", tsk->pid);
 276                         audit_log_untrustedstring(ab, tsk->comm);
 277                 }
 278                 break;
 279         case LSM_AUDIT_DATA_NET:
 280                 if (a->u.net.sk) {
 281                         struct sock *sk = a->u.net.sk;
 282                         struct unix_sock *u;
 283                         int len = 0;
 284                         char *p = NULL;
 285
 286                         switch (sk->sk_family) {
 287                         case AF_INET: {
 288                                 struct inet_sock *inet = inet_sk(sk);
 289
 290                                 print_ipv4_addr(ab, inet->inet_rcv_saddr,
 291                                                 inet->inet_sport,
 292                                                 "laddr", "lport");
 293                                 print_ipv4_addr(ab, inet->inet_daddr,
 294                                                 inet->inet_dport,
 295                                                 "faddr", "fport");
 296                                 break;
 297                         }
 298                         case AF_INET6: {
 299                                 struct inet_sock *inet = inet_sk(sk);
 300                                 struct ipv6_pinfo *inet6 = inet6_sk(sk);
 301
 302                                 print_ipv6_addr(ab, &inet6->rcv_saddr,
 303                                                 inet->inet_sport,
 304                                                 "laddr", "lport");
 305                                 print_ipv6_addr(ab, &inet6->daddr,
 306                                                 inet->inet_dport,
 307                                                 "faddr", "fport");
 308                                 break;
 309                         }
 310                         case AF_UNIX:
 311                                 u = unix_sk(sk);
 312                                 if (u->dentry) {
 313                                         struct path path = {
 314                                                 .dentry = u->dentry,
 315                                                 .mnt = u->mnt
 316                                         };
 317                                         audit_log_d_path(ab, "path=", &path);
 318                                         break;
 319                                 }
 320                                 if (!u->addr)
 321                                         break;
 322                                 len = u->addr->len-sizeof(short);
 323                                 p = &u->addr->name->sun_path[0];
 324                                 audit_log_format(ab, " path=");
 325                                 if (*p)
 326                                         audit_log_untrustedstring(ab, p);
 327                                 else
 328                                         audit_log_n_hex(ab, p, len);
 329                                 break;
 330                         }
 331                 }
 332
 333                 switch (a->u.net.family) {
 334                 case AF_INET:
 335                         print_ipv4_addr(ab, a->u.net.v4info.saddr,
 336                                         a->u.net.sport,
 337                                         "saddr", "src");
 338                         print_ipv4_addr(ab, a->u.net.v4info.daddr,
 339                                         a->u.net.dport,
 340                                         "daddr", "dest");
 341                         break;
 342                 case AF_INET6:
 343                         print_ipv6_addr(ab, &a->u.net.v6info.saddr,
 344                                         a->u.net.sport,
 345                                         "saddr", "src");
 346                         print_ipv6_addr(ab, &a->u.net.v6info.daddr,
 347                                         a->u.net.dport,
 348                                         "daddr", "dest");
 349                         break;
 350                 }
 351                 if (a->u.net.netif > 0) {
 352                         struct net_device *dev;
 353
 354                         /* NOTE: we always use init's namespace */
 355                         dev = dev_get_by_index(&init_net, a->u.net.netif);
 356                         if (dev) {
 357                                 audit_log_format(ab, " netif=%s", dev->name);
 358                                 dev_put(dev);
 359                         }
 360                 }
 361                 break;
 362 #ifdef CONFIG_KEYS
 363         case LSM_AUDIT_DATA_KEY:
 364                 audit_log_format(ab, " key_serial=%u", a->u.key_struct.key);
 365                 if (a->u.key_struct.key_desc) {
 366                         audit_log_format(ab, " key_desc=");
 367                         audit_log_untrustedstring(ab, a->u.key_struct.key_desc);
 368                 }
 369                 break;
 370 #endif
 371         case LSM_AUDIT_DATA_KMOD:
 372                 audit_log_format(ab, " kmod=");
 373                 audit_log_untrustedstring(ab, a->u.kmod_name);
 374                 break;
 375         } /* switch (a->type) */
 376 }
 377
 378 /**
 379  * common_lsm_audit - generic LSM auditing function
 380  * @a:  auxiliary audit data
 381  *
 382  * setup the audit buffer for common security information
 383  * uses callback to print LSM specific information
 384  */
 385 void common_lsm_audit(struct common_audit_data *a)
 386 {
 387         struct audit_buffer *ab;
 388
 389         if (a == NULL)
 390                 return;
 391         /* we use GFP_ATOMIC so we won't sleep */
 392         ab = audit_log_start(current->audit_context, GFP_ATOMIC, AUDIT_AVC);
 393
 394         if (ab == NULL)
 395                 return;
 396
 397         if (a->lsm_pre_audit)
 398                 a->lsm_pre_audit(ab, a);
 399
 400         dump_common_audit_data(ab, a);
 401
 402         if (a->lsm_post_audit)
 403                 a->lsm_post_audit(ab, a);
 404
 405         audit_log_end(ab);
 406 }