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
  31 /**
  32  * ipv4_skb_to_auditdata : fill auditdata from skb
  33  * @skb : the skb
  34  * @ad : the audit data to fill
  35  * @proto : the layer 4 protocol
  36  *
  37  * return  0 on success
  38  */
  39 int ipv4_skb_to_auditdata(struct sk_buff *skb,
  40                 struct common_audit_data *ad, u8 *proto)
  41 {
  42         int ret = 0;
  43         struct iphdr *ih;
  44
  45         ih = ip_hdr(skb);
  46         if (ih == NULL)
  47                 return -EINVAL;
  48
  49         ad->u.net->v4info.saddr = ih->saddr;
  50         ad->u.net->v4info.daddr = ih->daddr;
  51
  52         if (proto)
  53                 *proto = ih->protocol;
  54         /* non initial fragment */
  55         if (ntohs(ih->frag_off) & IP_OFFSET)
  56                 return 0;
  57
  58         switch (ih->protocol) {
  59         case IPPROTO_TCP: {
  60                 struct tcphdr *th = tcp_hdr(skb);
  61                 if (th == NULL)
  62                         break;
  63
  64                 ad->u.net->sport = th->source;
  65                 ad->u.net->dport = th->dest;
  66                 break;
  67         }
  68         case IPPROTO_UDP: {
  69                 struct udphdr *uh = udp_hdr(skb);
  70                 if (uh == NULL)
  71                         break;
  72
  73                 ad->u.net->sport = uh->source;
  74                 ad->u.net->dport = uh->dest;
  75                 break;
  76         }
  77         case IPPROTO_DCCP: {
  78                 struct dccp_hdr *dh = dccp_hdr(skb);
  79                 if (dh == NULL)
  80                         break;
  81
  82                 ad->u.net->sport = dh->dccph_sport;
  83                 ad->u.net->dport = dh->dccph_dport;
  84                 break;
  85         }
  86         case IPPROTO_SCTP: {
  87                 struct sctphdr *sh = sctp_hdr(skb);
  88                 if (sh == NULL)
  89                         break;
  90                 ad->u.net->sport = sh->source;
  91                 ad->u.net->dport = sh->dest;
  92                 break;
  93         }
  94         default:
  95                 ret = -EINVAL;
  96         }
  97         return ret;
  98 }
  99 #if IS_ENABLED(CONFIG_IPV6)
 100 /**
 101  * ipv6_skb_to_auditdata : fill auditdata from skb
 102  * @skb : the skb
 103  * @ad : the audit data to fill
 104  * @proto : the layer 4 protocol
 105  *
 106  * return  0 on success
 107  */
 108 int ipv6_skb_to_auditdata(struct sk_buff *skb,
 109                 struct common_audit_data *ad, u8 *proto)
 110 {
 111         int offset, ret = 0;
 112         struct ipv6hdr *ip6;
 113         u8 nexthdr;
 114         __be16 frag_off;
 115
 116         ip6 = ipv6_hdr(skb);
 117         if (ip6 == NULL)
 118                 return -EINVAL;
 119         ad->u.net->v6info.saddr = ip6->saddr;
 120         ad->u.net->v6info.daddr = ip6->daddr;
 121         ret = 0;
 122         /* IPv6 can have several extension header before the Transport header
 123          * skip them */
 124         offset = skb_network_offset(skb);
 125         offset += sizeof(*ip6);
 126         nexthdr = ip6->nexthdr;
 127         offset = ipv6_skip_exthdr(skb, offset, &nexthdr, &frag_off);
 128         if (offset < 0)
 129                 return 0;
 130         if (proto)
 131                 *proto = nexthdr;
 132         switch (nexthdr) {
 133         case IPPROTO_TCP: {
 134                 struct tcphdr _tcph, *th;
 135
 136                 th = skb_header_pointer(skb, offset, sizeof(_tcph), &_tcph);
 137                 if (th == NULL)
 138                         break;
 139
 140                 ad->u.net->sport = th->source;
 141                 ad->u.net->dport = th->dest;
 142                 break;
 143         }
 144         case IPPROTO_UDP: {
 145                 struct udphdr _udph, *uh;
 146
 147                 uh = skb_header_pointer(skb, offset, sizeof(_udph), &_udph);
 148                 if (uh == NULL)
 149                         break;
 150
 151                 ad->u.net->sport = uh->source;
 152                 ad->u.net->dport = uh->dest;
 153                 break;
 154         }
 155         case IPPROTO_DCCP: {
 156                 struct dccp_hdr _dccph, *dh;
 157
 158                 dh = skb_header_pointer(skb, offset, sizeof(_dccph), &_dccph);
 159                 if (dh == NULL)
 160                         break;
 161
 162                 ad->u.net->sport = dh->dccph_sport;
 163                 ad->u.net->dport = dh->dccph_dport;
 164                 break;
 165         }
 166         case IPPROTO_SCTP: {
 167                 struct sctphdr _sctph, *sh;
 168
 169                 sh = skb_header_pointer(skb, offset, sizeof(_sctph), &_sctph);
 170                 if (sh == NULL)
 171                         break;
 172                 ad->u.net->sport = sh->source;
 173                 ad->u.net->dport = sh->dest;
 174                 break;
 175         }
 176         default:
 177                 ret = -EINVAL;
 178         }
 179         return ret;
 180 }
 181 #endif
 182
 183
 184 static inline void print_ipv6_addr(struct audit_buffer *ab,
 185                                    struct in6_addr *addr, __be16 port,
 186                                    char *name1, char *name2)
 187 {
 188         if (!ipv6_addr_any(addr))
 189                 audit_log_format(ab, " %s=%pI6c", name1, addr);
 190         if (port)
 191                 audit_log_format(ab, " %s=%d", name2, ntohs(port));
 192 }
 193
 194 static inline void print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
 195                                    __be16 port, char *name1, char *name2)
 196 {
 197         if (addr)
 198                 audit_log_format(ab, " %s=%pI4", name1, &addr);
 199         if (port)
 200                 audit_log_format(ab, " %s=%d", name2, ntohs(port));
 201 }
 202
 203 /**
 204  * dump_common_audit_data - helper to dump common audit data
 205  * @a : common audit data
 206  *
 207  */
 208 static void dump_common_audit_data(struct audit_buffer *ab,
 209                                    struct common_audit_data *a)
 210 {
 211         char comm[sizeof(current->comm)];
 212
 213         /*
 214          * To keep stack sizes in check force programers to notice if they
 215          * start making this union too large!  See struct lsm_network_audit
 216          * as an example of how to deal with large data.
 217          */
 218         BUILD_BUG_ON(sizeof(a->u) > sizeof(void *)*2);
 219
 220         audit_log_format(ab, " pid=%d comm=", task_tgid_nr(current));
 221         audit_log_untrustedstring(ab, memcpy(comm, current->comm, sizeof(comm)));
 222
 223         switch (a->type) {
 224         case LSM_AUDIT_DATA_NONE:
 225                 return;
 226         case LSM_AUDIT_DATA_IPC:
 227                 audit_log_format(ab, " key=%d ", a->u.ipc_id);
 228                 break;
 229         case LSM_AUDIT_DATA_CAP:
 230                 audit_log_format(ab, " capability=%d ", a->u.cap);
 231                 break;
 232         case LSM_AUDIT_DATA_PATH: {
 233                 struct inode *inode;
 234
 235                 audit_log_d_path(ab, " path=", &a->u.path);
 236
 237                 inode = d_backing_inode(a->u.path.dentry);
 238                 if (inode) {
 239                         audit_log_format(ab, " dev=");
 240                         audit_log_untrustedstring(ab, inode->i_sb->s_id);
 241                         audit_log_format(ab, " ino=%lu", inode->i_ino);
 242                 }
 243                 break;
 244         }
 245         case LSM_AUDIT_DATA_FILE: {
 246                 struct inode *inode;
 247
 248                 audit_log_d_path(ab, " path=", &a->u.file->f_path);
 249
 250                 inode = file_inode(a->u.file);
 251                 if (inode) {
 252                         audit_log_format(ab, " dev=");
 253                         audit_log_untrustedstring(ab, inode->i_sb->s_id);
 254                         audit_log_format(ab, " ino=%lu", inode->i_ino);
 255                 }
 256                 break;
 257         }
 258         case LSM_AUDIT_DATA_IOCTL_OP: {
 259                 struct inode *inode;
 260
 261                 audit_log_d_path(ab, " path=", &a->u.op->path);
 262
 263                 inode = a->u.op->path.dentry->d_inode;
 264                 if (inode) {
 265                         audit_log_format(ab, " dev=");
 266                         audit_log_untrustedstring(ab, inode->i_sb->s_id);
 267                         audit_log_format(ab, " ino=%lu", inode->i_ino);
 268                 }
 269
 270                 audit_log_format(ab, " ioctlcmd=0x%hx", a->u.op->cmd);
 271                 break;
 272         }
 273         case LSM_AUDIT_DATA_DENTRY: {
 274                 struct inode *inode;
 275
 276                 audit_log_format(ab, " name=");
 277                 audit_log_untrustedstring(ab, a->u.dentry->d_name.name);
 278
 279                 inode = d_backing_inode(a->u.dentry);
 280                 if (inode) {
 281                         audit_log_format(ab, " dev=");
 282                         audit_log_untrustedstring(ab, inode->i_sb->s_id);
 283                         audit_log_format(ab, " ino=%lu", inode->i_ino);
 284                 }
 285                 break;
 286         }
 287         case LSM_AUDIT_DATA_INODE: {
 288                 struct dentry *dentry;
 289                 struct inode *inode;
 290
 291                 inode = a->u.inode;
 292                 dentry = d_find_alias(inode);
 293                 if (dentry) {
 294                         audit_log_format(ab, " name=");
 295                         audit_log_untrustedstring(ab,
 296                                          dentry->d_name.name);
 297                         dput(dentry);
 298                 }
 299                 audit_log_format(ab, " dev=");
 300                 audit_log_untrustedstring(ab, inode->i_sb->s_id);
 301                 audit_log_format(ab, " ino=%lu", inode->i_ino);
 302                 break;
 303         }
 304         case LSM_AUDIT_DATA_TASK: {
 305                 struct task_struct *tsk = a->u.tsk;
 306                 if (tsk) {
 307                         pid_t pid = task_tgid_nr(tsk);
 308                         if (pid) {
 309                                 char comm[sizeof(tsk->comm)];
 310                                 audit_log_format(ab, " opid=%d ocomm=", pid);
 311                                 audit_log_untrustedstring(ab,
 312                                     memcpy(comm, tsk->comm, sizeof(comm)));
 313                         }
 314                 }
 315                 break;
 316         }
 317         case LSM_AUDIT_DATA_NET:
 318                 if (a->u.net->sk) {
 319                         struct sock *sk = a->u.net->sk;
 320                         struct unix_sock *u;
 321                         struct unix_address *addr;
 322                         int len = 0;
 323                         char *p = NULL;
 324
 325                         switch (sk->sk_family) {
 326                         case AF_INET: {
 327                                 struct inet_sock *inet = inet_sk(sk);
 328
 329                                 print_ipv4_addr(ab, inet->inet_rcv_saddr,
 330                                                 inet->inet_sport,
 331                                                 "laddr", "lport");
 332                                 print_ipv4_addr(ab, inet->inet_daddr,
 333                                                 inet->inet_dport,
 334                                                 "faddr", "fport");
 335                                 break;
 336                         }
 337 #if IS_ENABLED(CONFIG_IPV6)
 338                         case AF_INET6: {
 339                                 struct inet_sock *inet = inet_sk(sk);
 340
 341                                 print_ipv6_addr(ab, &sk->sk_v6_rcv_saddr,
 342                                                 inet->inet_sport,
 343                                                 "laddr", "lport");
 344                                 print_ipv6_addr(ab, &sk->sk_v6_daddr,
 345                                                 inet->inet_dport,
 346                                                 "faddr", "fport");
 347                                 break;
 348                         }
 349 #endif
 350                         case AF_UNIX:
 351                                 u = unix_sk(sk);
 352                                 addr = smp_load_acquire(&u->addr);
 353                                 if (!addr)
 354                                         break;
 355                                 if (u->path.dentry) {
 356                                         audit_log_d_path(ab, " path=", &u->path);
 357                                         break;
 358                                 }
 359                                 len = addr->len-sizeof(short);
 360                                 p = &addr->name->sun_path[0];
 361                                 audit_log_format(ab, " path=");
 362                                 if (*p)
 363                                         audit_log_untrustedstring(ab, p);
 364                                 else
 365                                         audit_log_n_hex(ab, p, len);
 366                                 break;
 367                         }
 368                 }
 369
 370                 switch (a->u.net->family) {
 371                 case AF_INET:
 372                         print_ipv4_addr(ab, a->u.net->v4info.saddr,
 373                                         a->u.net->sport,
 374                                         "saddr", "src");
 375                         print_ipv4_addr(ab, a->u.net->v4info.daddr,
 376                                         a->u.net->dport,
 377                                         "daddr", "dest");
 378                         break;
 379                 case AF_INET6:
 380                         print_ipv6_addr(ab, &a->u.net->v6info.saddr,
 381                                         a->u.net->sport,
 382                                         "saddr", "src");
 383                         print_ipv6_addr(ab, &a->u.net->v6info.daddr,
 384                                         a->u.net->dport,
 385                                         "daddr", "dest");
 386                         break;
 387                 }
 388                 if (a->u.net->netif > 0) {
 389                         struct net_device *dev;
 390
 391                         /* NOTE: we always use init's namespace */
 392                         dev = dev_get_by_index(&init_net, a->u.net->netif);
 393                         if (dev) {
 394                                 audit_log_format(ab, " netif=%s", dev->name);
 395                                 dev_put(dev);
 396                         }
 397                 }
 398                 break;
 399 #ifdef CONFIG_KEYS
 400         case LSM_AUDIT_DATA_KEY:
 401                 audit_log_format(ab, " key_serial=%u", a->u.key_struct.key);
 402                 if (a->u.key_struct.key_desc) {
 403                         audit_log_format(ab, " key_desc=");
 404                         audit_log_untrustedstring(ab, a->u.key_struct.key_desc);
 405                 }
 406                 break;
 407 #endif
 408         case LSM_AUDIT_DATA_KMOD:
 409                 audit_log_format(ab, " kmod=");
 410                 audit_log_untrustedstring(ab, a->u.kmod_name);
 411                 break;
 412         case LSM_AUDIT_DATA_IBPKEY: {
 413                 struct in6_addr sbn_pfx;
 414
 415                 memset(&sbn_pfx.s6_addr, 0,
 416                        sizeof(sbn_pfx.s6_addr));
 417                 memcpy(&sbn_pfx.s6_addr, &a->u.ibpkey->subnet_prefix,
 418                        sizeof(a->u.ibpkey->subnet_prefix));
 419                 audit_log_format(ab, " pkey=0x%x subnet_prefix=%pI6c",
 420                                  a->u.ibpkey->pkey, &sbn_pfx);
 421                 break;
 422         }
 423         case LSM_AUDIT_DATA_IBENDPORT:
 424                 audit_log_format(ab, " device=%s port_num=%u",
 425                                  a->u.ibendport->dev_name,
 426                                  a->u.ibendport->port);
 427                 break;
 428         } /* switch (a->type) */
 429 }
 430
 431 /**
 432  * common_lsm_audit - generic LSM auditing function
 433  * @a:  auxiliary audit data
 434  * @pre_audit: lsm-specific pre-audit callback
 435  * @post_audit: lsm-specific post-audit callback
 436  *
 437  * setup the audit buffer for common security information
 438  * uses callback to print LSM specific information
 439  */
 440 void common_lsm_audit(struct common_audit_data *a,
 441         void (*pre_audit)(struct audit_buffer *, void *),
 442         void (*post_audit)(struct audit_buffer *, void *))
 443 {
 444         struct audit_buffer *ab;
 445
 446         if (a == NULL)
 447                 return;
 448         /* we use GFP_ATOMIC so we won't sleep */
 449         ab = audit_log_start(audit_context(), GFP_ATOMIC | __GFP_NOWARN,
 450                              AUDIT_AVC);
 451
 452         if (ab == NULL)
 453                 return;
 454
 455         if (pre_audit)
 456                 pre_audit(ab, a);
 457
 458         dump_common_audit_data(ab, a);
 459
 460         if (post_audit)
 461                 post_audit(ab, a);
 462
 463         audit_log_end(ab);
 464 }