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_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                 spin_lock(&a->u.dentry->d_lock);
 268                 audit_log_untrustedstring(ab, a->u.dentry->d_name.name);
 269                 spin_unlock(&a->u.dentry->d_lock);
 270
 271                 inode = d_backing_inode(a->u.dentry);
 272                 if (inode) {
 273                         audit_log_format(ab, " dev=");
 274                         audit_log_untrustedstring(ab, inode->i_sb->s_id);
 275                         audit_log_format(ab, " ino=%lu", inode->i_ino);
 276                 }
 277                 break;
 278         }
 279         case LSM_AUDIT_DATA_INODE: {
 280                 struct dentry *dentry;
 281                 struct inode *inode;
 282
 283                 inode = a->u.inode;
 284                 dentry = d_find_alias(inode);
 285                 if (dentry) {
 286                         audit_log_format(ab, " name=");
 287                         spin_lock(&dentry->d_lock);
 288                         audit_log_untrustedstring(ab, dentry->d_name.name);
 289                         spin_unlock(&dentry->d_lock);
 290                         dput(dentry);
 291                 }
 292                 audit_log_format(ab, " dev=");
 293                 audit_log_untrustedstring(ab, inode->i_sb->s_id);
 294                 audit_log_format(ab, " ino=%lu", inode->i_ino);
 295                 break;
 296         }
 297         case LSM_AUDIT_DATA_TASK: {
 298                 struct task_struct *tsk = a->u.tsk;
 299                 if (tsk) {
 300                         pid_t pid = task_pid_nr(tsk);
 301                         if (pid) {
 302                                 char comm[sizeof(tsk->comm)];
 303                                 audit_log_format(ab, " opid=%d ocomm=", pid);
 304                                 audit_log_untrustedstring(ab,
 305                                     memcpy(comm, tsk->comm, sizeof(comm)));
 306                         }
 307                 }
 308                 break;
 309         }
 310         case LSM_AUDIT_DATA_NET:
 311                 if (a->u.net->sk) {
 312                         struct sock *sk = a->u.net->sk;
 313                         struct unix_sock *u;
 314                         struct unix_address *addr;
 315                         int len = 0;
 316                         char *p = NULL;
 317
 318                         switch (sk->sk_family) {
 319                         case AF_INET: {
 320                                 struct inet_sock *inet = inet_sk(sk);
 321
 322                                 print_ipv4_addr(ab, inet->inet_rcv_saddr,
 323                                                 inet->inet_sport,
 324                                                 "laddr", "lport");
 325                                 print_ipv4_addr(ab, inet->inet_daddr,
 326                                                 inet->inet_dport,
 327                                                 "faddr", "fport");
 328                                 break;
 329                         }
 330 #if IS_ENABLED(CONFIG_IPV6)
 331                         case AF_INET6: {
 332                                 struct inet_sock *inet = inet_sk(sk);
 333
 334                                 print_ipv6_addr(ab, &sk->sk_v6_rcv_saddr,
 335                                                 inet->inet_sport,
 336                                                 "laddr", "lport");
 337                                 print_ipv6_addr(ab, &sk->sk_v6_daddr,
 338                                                 inet->inet_dport,
 339                                                 "faddr", "fport");
 340                                 break;
 341                         }
 342 #endif
 343                         case AF_UNIX:
 344                                 u = unix_sk(sk);
 345                                 addr = smp_load_acquire(&u->addr);
 346                                 if (!addr)
 347                                         break;
 348                                 if (u->path.dentry) {
 349                                         audit_log_d_path(ab, " path=", &u->path);
 350                                         break;
 351                                 }
 352                                 len = addr->len-sizeof(short);
 353                                 p = &addr->name->sun_path[0];
 354                                 audit_log_format(ab, " path=");
 355                                 if (*p)
 356                                         audit_log_untrustedstring(ab, p);
 357                                 else
 358                                         audit_log_n_hex(ab, p, len);
 359                                 break;
 360                         }
 361                 }
 362
 363                 switch (a->u.net->family) {
 364                 case AF_INET:
 365                         print_ipv4_addr(ab, a->u.net->v4info.saddr,
 366                                         a->u.net->sport,
 367                                         "saddr", "src");
 368                         print_ipv4_addr(ab, a->u.net->v4info.daddr,
 369                                         a->u.net->dport,
 370                                         "daddr", "dest");
 371                         break;
 372                 case AF_INET6:
 373                         print_ipv6_addr(ab, &a->u.net->v6info.saddr,
 374                                         a->u.net->sport,
 375                                         "saddr", "src");
 376                         print_ipv6_addr(ab, &a->u.net->v6info.daddr,
 377                                         a->u.net->dport,
 378                                         "daddr", "dest");
 379                         break;
 380                 }
 381                 if (a->u.net->netif > 0) {
 382                         struct net_device *dev;
 383
 384                         /* NOTE: we always use init's namespace */
 385                         dev = dev_get_by_index(&init_net, a->u.net->netif);
 386                         if (dev) {
 387                                 audit_log_format(ab, " netif=%s", dev->name);
 388                                 dev_put(dev);
 389                         }
 390                 }
 391                 break;
 392 #ifdef CONFIG_KEYS
 393         case LSM_AUDIT_DATA_KEY:
 394                 audit_log_format(ab, " key_serial=%u", a->u.key_struct.key);
 395                 if (a->u.key_struct.key_desc) {
 396                         audit_log_format(ab, " key_desc=");
 397                         audit_log_untrustedstring(ab, a->u.key_struct.key_desc);
 398                 }
 399                 break;
 400 #endif
 401         case LSM_AUDIT_DATA_KMOD:
 402                 audit_log_format(ab, " kmod=");
 403                 audit_log_untrustedstring(ab, a->u.kmod_name);
 404                 break;
 405         } /* switch (a->type) */
 406 }
 407
 408 /**
 409  * common_lsm_audit - generic LSM auditing function
 410  * @a:  auxiliary audit data
 411  * @pre_audit: lsm-specific pre-audit callback
 412  * @post_audit: lsm-specific post-audit callback
 413  *
 414  * setup the audit buffer for common security information
 415  * uses callback to print LSM specific information
 416  */
 417 void common_lsm_audit(struct common_audit_data *a,
 418         void (*pre_audit)(struct audit_buffer *, void *),
 419         void (*post_audit)(struct audit_buffer *, void *))
 420 {
 421         struct audit_buffer *ab;
 422
 423         if (a == NULL)
 424                 return;
 425         /* we use GFP_ATOMIC so we won't sleep */
 426         ab = audit_log_start(current->audit_context, GFP_ATOMIC | __GFP_NOWARN,
 427                              AUDIT_AVC);
 428
 429         if (ab == NULL)
 430                 return;
 431
 432         if (pre_audit)
 433                 pre_audit(ab, a);
 434
 435         dump_common_audit_data(ab, a);
 436
 437         if (post_audit)
 438                 post_audit(ab, a);
 439
 440         audit_log_end(ab);
 441 }