security/lsm_audit.c

   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
  11 #include <linux/types.h>
  12 #include <linux/stddef.h>
  13 #include <linux/kernel.h>
  14 #include <linux/gfp.h>
  15 #include <linux/fs.h>
  16 #include <linux/init.h>
  17 #include <net/sock.h>
  18 #include <linux/un.h>
  19 #include <net/af_unix.h>
  20 #include <linux/audit.h>
  21 #include <linux/ipv6.h>
  22 #include <linux/ip.h>
  23 #include <net/ip.h>
  24 #include <net/ipv6.h>
  25 #include <linux/tcp.h>
  26 #include <linux/udp.h>
  27 #include <linux/dccp.h>
  28 #include <linux/sctp.h>
  29 #include <linux/lsm_audit.h>
  30 #include <linux/security.h>
  31
  32 /**
  33  * ipv4_skb_to_auditdata : fill auditdata from skb
  34  * @skb : the skb
  35  * @ad : the audit data to fill
  36  * @proto : the layer 4 protocol
  37  *
  38  * return  0 on success
  39  */
  40 int ipv4_skb_to_auditdata(struct sk_buff *skb,
  41                 struct common_audit_data *ad, u8 *proto)
  42 {
  43         int ret = 0;
  44         struct iphdr *ih;
  45
  46         ih = ip_hdr(skb);
  47         if (ih == NULL)
  48                 return -EINVAL;
  49
  50         ad->u.net->v4info.saddr = ih->saddr;
  51         ad->u.net->v4info.daddr = ih->daddr;
  52
  53         if (proto)
  54                 *proto = ih->protocol;
  55         /* non initial fragment */
  56         if (ntohs(ih->frag_off) & IP_OFFSET)
  57                 return 0;
  58
  59         switch (ih->protocol) {
  60         case IPPROTO_TCP: {
  61                 struct tcphdr *th = tcp_hdr(skb);
  62                 if (th == NULL)
  63                         break;
  64
  65                 ad->u.net->sport = th->source;
  66                 ad->u.net->dport = th->dest;
  67                 break;
  68         }
  69         case IPPROTO_UDP: {
  70                 struct udphdr *uh = udp_hdr(skb);
  71                 if (uh == NULL)
  72                         break;
  73
  74                 ad->u.net->sport = uh->source;
  75                 ad->u.net->dport = uh->dest;
  76                 break;
  77         }
  78         case IPPROTO_DCCP: {
  79                 struct dccp_hdr *dh = dccp_hdr(skb);
  80                 if (dh == NULL)
  81                         break;
  82
  83                 ad->u.net->sport = dh->dccph_sport;
  84                 ad->u.net->dport = dh->dccph_dport;
  85                 break;
  86         }
  87         case IPPROTO_SCTP: {
  88                 struct sctphdr *sh = sctp_hdr(skb);
  89                 if (sh == NULL)
  90                         break;
  91                 ad->u.net->sport = sh->source;
  92                 ad->u.net->dport = sh->dest;
  93                 break;
  94         }
  95         default:
  96                 ret = -EINVAL;
  97         }
  98         return ret;
  99 }
 100 #if IS_ENABLED(CONFIG_IPV6)
 101 /**
 102  * ipv6_skb_to_auditdata : fill auditdata from skb
 103  * @skb : the skb
 104  * @ad : the audit data to fill
 105  * @proto : the layer 4 protocol
 106  *
 107  * return  0 on success
 108  */
 109 int ipv6_skb_to_auditdata(struct sk_buff *skb,
 110                 struct common_audit_data *ad, u8 *proto)
 111 {
 112         int offset, ret = 0;
 113         struct ipv6hdr *ip6;
 114         u8 nexthdr;
 115         __be16 frag_off;
 116
 117         ip6 = ipv6_hdr(skb);
 118         if (ip6 == NULL)
 119                 return -EINVAL;
 120         ad->u.net->v6info.saddr = ip6->saddr;
 121         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, &frag_off);
 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         char comm[sizeof(current->comm)];
 213
 214         /*
 215          * To keep stack sizes in check force programers to notice if they
 216          * start making this union too large!  See struct lsm_network_audit
 217          * as an example of how to deal with large data.
 218          */
 219         BUILD_BUG_ON(sizeof(a->u) > sizeof(void *)*2);
 220
 221         audit_log_format(ab, " pid=%d comm=", task_tgid_nr(current));
 222         audit_log_untrustedstring(ab, memcpy(comm, current->comm, sizeof(comm)));
 223
 224         switch (a->type) {
 225         case LSM_AUDIT_DATA_NONE:
 226                 return;
 227         case LSM_AUDIT_DATA_IPC:
 228                 audit_log_format(ab, " key=%d ", a->u.ipc_id);
 229                 break;
 230         case LSM_AUDIT_DATA_CAP:
 231                 audit_log_format(ab, " capability=%d ", a->u.cap);
 232                 break;
 233         case LSM_AUDIT_DATA_PATH: {
 234                 struct inode *inode;
 235
 236                 audit_log_d_path(ab, " path=", &a->u.path);
 237
 238                 inode = d_backing_inode(a->u.path.dentry);
 239                 if (inode) {
 240                         audit_log_format(ab, " dev=");
 241                         audit_log_untrustedstring(ab, inode->i_sb->s_id);
 242                         audit_log_format(ab, " ino=%lu", inode->i_ino);
 243                 }
 244                 break;
 245         }
 246         case LSM_AUDIT_DATA_FILE: {
 247                 struct inode *inode;
 248
 249                 audit_log_d_path(ab, " path=", &a->u.file->f_path);
 250
 251                 inode = file_inode(a->u.file);
 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                 break;
 258         }
 259         case LSM_AUDIT_DATA_IOCTL_OP: {
 260                 struct inode *inode;
 261
 262                 audit_log_d_path(ab, " path=", &a->u.op->path);
 263
 264                 inode = a->u.op->path.dentry->d_inode;
 265                 if (inode) {
 266                         audit_log_format(ab, " dev=");
 267                         audit_log_untrustedstring(ab, inode->i_sb->s_id);
 268                         audit_log_format(ab, " ino=%lu", inode->i_ino);
 269                 }
 270
 271                 audit_log_format(ab, " ioctlcmd=0x%hx", a->u.op->cmd);
 272                 break;
 273         }
 274         case LSM_AUDIT_DATA_DENTRY: {
 275                 struct inode *inode;
 276
 277                 audit_log_format(ab, " name=");
 278                 audit_log_untrustedstring(ab, a->u.dentry->d_name.name);
 279
 280                 inode = d_backing_inode(a->u.dentry);
 281                 if (inode) {
 282                         audit_log_format(ab, " dev=");
 283                         audit_log_untrustedstring(ab, inode->i_sb->s_id);
 284                         audit_log_format(ab, " ino=%lu", inode->i_ino);
 285                 }
 286                 break;
 287         }
 288         case LSM_AUDIT_DATA_INODE: {
 289                 struct dentry *dentry;
 290                 struct inode *inode;
 291
 292                 inode = a->u.inode;
 293                 dentry = d_find_alias(inode);
 294                 if (dentry) {
 295                         audit_log_format(ab, " name=");
 296                         audit_log_untrustedstring(ab,
 297                                          dentry->d_name.name);
 298                         dput(dentry);
 299                 }
 300                 audit_log_format(ab, " dev=");
 301                 audit_log_untrustedstring(ab, inode->i_sb->s_id);
 302                 audit_log_format(ab, " ino=%lu", inode->i_ino);
 303                 break;
 304         }
 305         case LSM_AUDIT_DATA_TASK: {
 306                 struct task_struct *tsk = a->u.tsk;
 307                 if (tsk) {
 308                         pid_t pid = task_tgid_nr(tsk);
 309                         if (pid) {
 310                                 char comm[sizeof(tsk->comm)];
 311                                 audit_log_format(ab, " opid=%d ocomm=", pid);
 312                                 audit_log_untrustedstring(ab,
 313                                     memcpy(comm, tsk->comm, sizeof(comm)));
 314                         }
 315                 }
 316                 break;
 317         }
 318         case LSM_AUDIT_DATA_NET:
 319                 if (a->u.net->sk) {
 320                         struct sock *sk = a->u.net->sk;
 321                         struct unix_sock *u;
 322                         struct unix_address *addr;
 323                         int len = 0;
 324                         char *p = NULL;
 325
 326                         switch (sk->sk_family) {
 327                         case AF_INET: {
 328                                 struct inet_sock *inet = inet_sk(sk);
 329
 330                                 print_ipv4_addr(ab, inet->inet_rcv_saddr,
 331                                                 inet->inet_sport,
 332                                                 "laddr", "lport");
 333                                 print_ipv4_addr(ab, inet->inet_daddr,
 334                                                 inet->inet_dport,
 335                                                 "faddr", "fport");
 336                                 break;
 337                         }
 338 #if IS_ENABLED(CONFIG_IPV6)
 339                         case AF_INET6: {
 340                                 struct inet_sock *inet = inet_sk(sk);
 341
 342                                 print_ipv6_addr(ab, &sk->sk_v6_rcv_saddr,
 343                                                 inet->inet_sport,
 344                                                 "laddr", "lport");
 345                                 print_ipv6_addr(ab, &sk->sk_v6_daddr,
 346                                                 inet->inet_dport,
 347                                                 "faddr", "fport");
 348                                 break;
 349                         }
 350 #endif
 351                         case AF_UNIX:
 352                                 u = unix_sk(sk);
 353                                 addr = smp_load_acquire(&u->addr);
 354                                 if (!addr)
 355                                         break;
 356                                 if (u->path.dentry) {
 357                                         audit_log_d_path(ab, " path=", &u->path);
 358                                         break;
 359                                 }
 360                                 len = addr->len-sizeof(short);
 361                                 p = &addr->name->sun_path[0];
 362                                 audit_log_format(ab, " path=");
 363                                 if (*p)
 364                                         audit_log_untrustedstring(ab, p);
 365                                 else
 366                                         audit_log_n_hex(ab, p, len);
 367                                 break;
 368                         }
 369                 }
 370
 371                 switch (a->u.net->family) {
 372                 case AF_INET:
 373                         print_ipv4_addr(ab, a->u.net->v4info.saddr,
 374                                         a->u.net->sport,
 375                                         "saddr", "src");
 376                         print_ipv4_addr(ab, a->u.net->v4info.daddr,
 377                                         a->u.net->dport,
 378                                         "daddr", "dest");
 379                         break;
 380                 case AF_INET6:
 381                         print_ipv6_addr(ab, &a->u.net->v6info.saddr,
 382                                         a->u.net->sport,
 383                                         "saddr", "src");
 384                         print_ipv6_addr(ab, &a->u.net->v6info.daddr,
 385                                         a->u.net->dport,
 386                                         "daddr", "dest");
 387                         break;
 388                 }
 389                 if (a->u.net->netif > 0) {
 390                         struct net_device *dev;
 391
 392                         /* NOTE: we always use init's namespace */
 393                         dev = dev_get_by_index(&init_net, a->u.net->netif);
 394                         if (dev) {
 395                                 audit_log_format(ab, " netif=%s", dev->name);
 396                                 dev_put(dev);
 397                         }
 398                 }
 399                 break;
 400 #ifdef CONFIG_KEYS
 401         case LSM_AUDIT_DATA_KEY:
 402                 audit_log_format(ab, " key_serial=%u", a->u.key_struct.key);
 403                 if (a->u.key_struct.key_desc) {
 404                         audit_log_format(ab, " key_desc=");
 405                         audit_log_untrustedstring(ab, a->u.key_struct.key_desc);
 406                 }
 407                 break;
 408 #endif
 409         case LSM_AUDIT_DATA_KMOD:
 410                 audit_log_format(ab, " kmod=");
 411                 audit_log_untrustedstring(ab, a->u.kmod_name);
 412                 break;
 413         case LSM_AUDIT_DATA_IBPKEY: {
 414                 struct in6_addr sbn_pfx;
 415
 416                 memset(&sbn_pfx.s6_addr, 0,
 417                        sizeof(sbn_pfx.s6_addr));
 418                 memcpy(&sbn_pfx.s6_addr, &a->u.ibpkey->subnet_prefix,
 419                        sizeof(a->u.ibpkey->subnet_prefix));
 420                 audit_log_format(ab, " pkey=0x%x subnet_prefix=%pI6c",
 421                                  a->u.ibpkey->pkey, &sbn_pfx);
 422                 break;
 423         }
 424         case LSM_AUDIT_DATA_IBENDPORT:
 425                 audit_log_format(ab, " device=%s port_num=%u",
 426                                  a->u.ibendport->dev_name,
 427                                  a->u.ibendport->port);
 428                 break;
 429         case LSM_AUDIT_DATA_LOCKDOWN:
 430                 audit_log_format(ab, " lockdown_reason=");
 431                 audit_log_string(ab, lockdown_reasons[a->u.reason]);
 432                 break;
 433         } /* switch (a->type) */
 434 }
 435
 436 /**
 437  * common_lsm_audit - generic LSM auditing function
 438  * @a:  auxiliary audit data
 439  * @pre_audit: lsm-specific pre-audit callback
 440  * @post_audit: lsm-specific post-audit callback
 441  *
 442  * setup the audit buffer for common security information
 443  * uses callback to print LSM specific information
 444  */
 445 void common_lsm_audit(struct common_audit_data *a,
 446         void (*pre_audit)(struct audit_buffer *, void *),
 447         void (*post_audit)(struct audit_buffer *, void *))
 448 {
 449         struct audit_buffer *ab;
 450
 451         if (a == NULL)
 452                 return;
 453         /* we use GFP_ATOMIC so we won't sleep */
 454         ab = audit_log_start(audit_context(), GFP_ATOMIC | __GFP_NOWARN,
 455                              AUDIT_AVC);
 456
 457         if (ab == NULL)
 458                 return;
 459
 460         if (pre_audit)
 461                 pre_audit(ab, a);
 462
 463         dump_common_audit_data(ab, a);
 464
 465         if (post_audit)
 466                 post_audit(ab, a);
 467
 468         audit_log_end(ab);
 469 }