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/fs.h>
  18 #include <linux/init.h>
  19 #include <net/sock.h>
  20 #include <linux/un.h>
  21 #include <net/af_unix.h>
  22 #include <linux/audit.h>
  23 #include <linux/ipv6.h>
  24 #include <linux/ip.h>
  25 #include <net/ip.h>
  26 #include <net/ipv6.h>
  27 #include <linux/tcp.h>
  28 #include <linux/udp.h>
  29 #include <linux/dccp.h>
  30 #include <linux/sctp.h>
  31 #include <linux/lsm_audit.h>
  32
  33 /**
  34  * ipv4_skb_to_auditdata : fill auditdata from skb
  35  * @skb : the skb
  36  * @ad : the audit data to fill
  37  * @proto : the layer 4 protocol
  38  *
  39  * return  0 on success
  40  */
  41 int ipv4_skb_to_auditdata(struct sk_buff *skb,
  42                 struct common_audit_data *ad, u8 *proto)
  43 {
  44         int ret = 0;
  45         struct iphdr *ih;
  46
  47         ih = ip_hdr(skb);
  48         if (ih == NULL)
  49                 return -EINVAL;
  50
  51         ad->u.net.v4info.saddr = ih->saddr;
  52         ad->u.net.v4info.daddr = ih->daddr;
  53
  54         if (proto)
  55                 *proto = ih->protocol;
  56         /* non initial fragment */
  57         if (ntohs(ih->frag_off) & IP_OFFSET)
  58                 return 0;
  59
  60         switch (ih->protocol) {
  61         case IPPROTO_TCP: {
  62                 struct tcphdr *th = tcp_hdr(skb);
  63                 if (th == NULL)
  64                         break;
  65
  66                 ad->u.net.sport = th->source;
  67                 ad->u.net.dport = th->dest;
  68                 break;
  69         }
  70         case IPPROTO_UDP: {
  71                 struct udphdr *uh = udp_hdr(skb);
  72                 if (uh == NULL)
  73                         break;
  74
  75                 ad->u.net.sport = uh->source;
  76                 ad->u.net.dport = uh->dest;
  77                 break;
  78         }
  79         case IPPROTO_DCCP: {
  80                 struct dccp_hdr *dh = dccp_hdr(skb);
  81                 if (dh == NULL)
  82                         break;
  83
  84                 ad->u.net.sport = dh->dccph_sport;
  85                 ad->u.net.dport = dh->dccph_dport;
  86                 break;
  87         }
  88         case IPPROTO_SCTP: {
  89                 struct sctphdr *sh = sctp_hdr(skb);
  90                 if (sh == NULL)
  91                         break;
  92                 ad->u.net.sport = sh->source;
  93                 ad->u.net.dport = sh->dest;
  94                 break;
  95         }
  96         default:
  97                 ret = -EINVAL;
  98         }
  99         return ret;
 100 }
 101 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
 102 /**
 103  * ipv6_skb_to_auditdata : fill auditdata from skb
 104  * @skb : the skb
 105  * @ad : the audit data to fill
 106  * @proto : the layer 4 protocol
 107  *
 108  * return  0 on success
 109  */
 110 int ipv6_skb_to_auditdata(struct sk_buff *skb,
 111                 struct common_audit_data *ad, u8 *proto)
 112 {
 113         int offset, ret = 0;
 114         struct ipv6hdr *ip6;
 115         u8 nexthdr;
 116
 117         ip6 = ipv6_hdr(skb);
 118         if (ip6 == NULL)
 119                 return -EINVAL;
 120         ipv6_addr_copy(&ad->u.net.v6info.saddr, &ip6->saddr);
 121         ipv6_addr_copy(&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);
 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         struct inode *inode = NULL;
 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_NO_AUDIT:
 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_FS:
 232                 if (a->u.fs.path.dentry) {
 233                         struct dentry *dentry = a->u.fs.path.dentry;
 234                         if (a->u.fs.path.mnt) {
 235                                 audit_log_d_path(ab, "path=", &a->u.fs.path);
 236                         } else {
 237                                 audit_log_format(ab, " name=");
 238                                 audit_log_untrustedstring(ab,
 239                                                  dentry->d_name.name);
 240                         }
 241                         inode = dentry->d_inode;
 242                 } else if (a->u.fs.inode) {
 243                         struct dentry *dentry;
 244                         inode = a->u.fs.inode;
 245                         dentry = d_find_alias(inode);
 246                         if (dentry) {
 247                                 audit_log_format(ab, " name=");
 248                                 audit_log_untrustedstring(ab,
 249                                                  dentry->d_name.name);
 250                                 dput(dentry);
 251                         }
 252                 }
 253                 if (inode)
 254                         audit_log_format(ab, " dev=%s ino=%lu",
 255                                         inode->i_sb->s_id,
 256                                         inode->i_ino);
 257                 break;
 258         case LSM_AUDIT_DATA_TASK:
 259                 tsk = a->u.tsk;
 260                 if (tsk && tsk->pid) {
 261                         audit_log_format(ab, " pid=%d comm=", tsk->pid);
 262                         audit_log_untrustedstring(ab, tsk->comm);
 263                 }
 264                 break;
 265         case LSM_AUDIT_DATA_NET:
 266                 if (a->u.net.sk) {
 267                         struct sock *sk = a->u.net.sk;
 268                         struct unix_sock *u;
 269                         int len = 0;
 270                         char *p = NULL;
 271
 272                         switch (sk->sk_family) {
 273                         case AF_INET: {
 274                                 struct inet_sock *inet = inet_sk(sk);
 275
 276                                 print_ipv4_addr(ab, inet->rcv_saddr,
 277                                                 inet->sport,
 278                                                 "laddr", "lport");
 279                                 print_ipv4_addr(ab, inet->daddr,
 280                                                 inet->dport,
 281                                                 "faddr", "fport");
 282                                 break;
 283                         }
 284                         case AF_INET6: {
 285                                 struct inet_sock *inet = inet_sk(sk);
 286                                 struct ipv6_pinfo *inet6 = inet6_sk(sk);
 287
 288                                 print_ipv6_addr(ab, &inet6->rcv_saddr,
 289                                                 inet->sport,
 290                                                 "laddr", "lport");
 291                                 print_ipv6_addr(ab, &inet6->daddr,
 292                                                 inet->dport,
 293                                                 "faddr", "fport");
 294                                 break;
 295                         }
 296                         case AF_UNIX:
 297                                 u = unix_sk(sk);
 298                                 if (u->dentry) {
 299                                         struct path path = {
 300                                                 .dentry = u->dentry,
 301                                                 .mnt = u->mnt
 302                                         };
 303                                         audit_log_d_path(ab, "path=", &path);
 304                                         break;
 305                                 }
 306                                 if (!u->addr)
 307                                         break;
 308                                 len = u->addr->len-sizeof(short);
 309                                 p = &u->addr->name->sun_path[0];
 310                                 audit_log_format(ab, " path=");
 311                                 if (*p)
 312                                         audit_log_untrustedstring(ab, p);
 313                                 else
 314                                         audit_log_n_hex(ab, p, len);
 315                                 break;
 316                         }
 317                 }
 318
 319                 switch (a->u.net.family) {
 320                 case AF_INET:
 321                         print_ipv4_addr(ab, a->u.net.v4info.saddr,
 322                                         a->u.net.sport,
 323                                         "saddr", "src");
 324                         print_ipv4_addr(ab, a->u.net.v4info.daddr,
 325                                         a->u.net.dport,
 326                                         "daddr", "dest");
 327                         break;
 328                 case AF_INET6:
 329                         print_ipv6_addr(ab, &a->u.net.v6info.saddr,
 330                                         a->u.net.sport,
 331                                         "saddr", "src");
 332                         print_ipv6_addr(ab, &a->u.net.v6info.daddr,
 333                                         a->u.net.dport,
 334                                         "daddr", "dest");
 335                         break;
 336                 }
 337                 if (a->u.net.netif > 0) {
 338                         struct net_device *dev;
 339
 340                         /* NOTE: we always use init's namespace */
 341                         dev = dev_get_by_index(&init_net, a->u.net.netif);
 342                         if (dev) {
 343                                 audit_log_format(ab, " netif=%s", dev->name);
 344                                 dev_put(dev);
 345                         }
 346                 }
 347                 break;
 348 #ifdef CONFIG_KEYS
 349         case LSM_AUDIT_DATA_KEY:
 350                 audit_log_format(ab, " key_serial=%u", a->u.key_struct.key);
 351                 if (a->u.key_struct.key_desc) {
 352                         audit_log_format(ab, " key_desc=");
 353                         audit_log_untrustedstring(ab, a->u.key_struct.key_desc);
 354                 }
 355                 break;
 356 #endif
 357         } /* switch (a->type) */
 358 }
 359
 360 /**
 361  * common_lsm_audit - generic LSM auditing function
 362  * @a:  auxiliary audit data
 363  *
 364  * setup the audit buffer for common security information
 365  * uses callback to print LSM specific information
 366  */
 367 void common_lsm_audit(struct common_audit_data *a)
 368 {
 369         struct audit_buffer *ab;
 370
 371         if (a == NULL)
 372                 return;
 373         /* we use GFP_ATOMIC so we won't sleep */
 374         ab = audit_log_start(current->audit_context, GFP_ATOMIC, AUDIT_AVC);
 375
 376         if (ab == NULL)
 377                 return;
 378
 379         if (a->lsm_pre_audit)
 380                 a->lsm_pre_audit(ab, a);
 381
 382         dump_common_audit_data(ab, a);
 383
 384         if (a->lsm_post_audit)
 385                 a->lsm_post_audit(ab, a);
 386
 387         audit_log_end(ab);
 388 }