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         /* 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                                    const 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, " ipc_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                 spin_lock(&a->u.dentry->d_lock);
 278                 audit_log_untrustedstring(ab, a->u.dentry->d_name.name);
 279                 spin_unlock(&a->u.dentry->d_lock);
 280
 281                 inode = d_backing_inode(a->u.dentry);
 282                 if (inode) {
 283                         audit_log_format(ab, " dev=");
 284                         audit_log_untrustedstring(ab, inode->i_sb->s_id);
 285                         audit_log_format(ab, " ino=%lu", inode->i_ino);
 286                 }
 287                 break;
 288         }
 289         case LSM_AUDIT_DATA_INODE: {
 290                 struct dentry *dentry;
 291                 struct inode *inode;
 292
 293                 rcu_read_lock();
 294                 inode = a->u.inode;
 295                 dentry = d_find_alias_rcu(inode);
 296                 if (dentry) {
 297                         audit_log_format(ab, " name=");
 298                         spin_lock(&dentry->d_lock);
 299                         audit_log_untrustedstring(ab, dentry->d_name.name);
 300                         spin_unlock(&dentry->d_lock);
 301                 }
 302                 audit_log_format(ab, " dev=");
 303                 audit_log_untrustedstring(ab, inode->i_sb->s_id);
 304                 audit_log_format(ab, " ino=%lu", inode->i_ino);
 305                 rcu_read_unlock();
 306                 break;
 307         }
 308         case LSM_AUDIT_DATA_TASK: {
 309                 struct task_struct *tsk = a->u.tsk;
 310                 if (tsk) {
 311                         pid_t pid = task_tgid_nr(tsk);
 312                         if (pid) {
 313                                 char comm[sizeof(tsk->comm)];
 314                                 audit_log_format(ab, " opid=%d ocomm=", pid);
 315                                 audit_log_untrustedstring(ab,
 316                                     memcpy(comm, tsk->comm, sizeof(comm)));
 317                         }
 318                 }
 319                 break;
 320         }
 321         case LSM_AUDIT_DATA_NET:
 322                 if (a->u.net->sk) {
 323                         const struct sock *sk = a->u.net->sk;
 324                         struct unix_sock *u;
 325                         struct unix_address *addr;
 326                         int len = 0;
 327                         char *p = NULL;
 328
 329                         switch (sk->sk_family) {
 330                         case AF_INET: {
 331                                 struct inet_sock *inet = inet_sk(sk);
 332
 333                                 print_ipv4_addr(ab, inet->inet_rcv_saddr,
 334                                                 inet->inet_sport,
 335                                                 "laddr", "lport");
 336                                 print_ipv4_addr(ab, inet->inet_daddr,
 337                                                 inet->inet_dport,
 338                                                 "faddr", "fport");
 339                                 break;
 340                         }
 341 #if IS_ENABLED(CONFIG_IPV6)
 342                         case AF_INET6: {
 343                                 struct inet_sock *inet = inet_sk(sk);
 344
 345                                 print_ipv6_addr(ab, &sk->sk_v6_rcv_saddr,
 346                                                 inet->inet_sport,
 347                                                 "laddr", "lport");
 348                                 print_ipv6_addr(ab, &sk->sk_v6_daddr,
 349                                                 inet->inet_dport,
 350                                                 "faddr", "fport");
 351                                 break;
 352                         }
 353 #endif
 354                         case AF_UNIX:
 355                                 u = unix_sk(sk);
 356                                 addr = smp_load_acquire(&u->addr);
 357                                 if (!addr)
 358                                         break;
 359                                 if (u->path.dentry) {
 360                                         audit_log_d_path(ab, " path=", &u->path);
 361                                         break;
 362                                 }
 363                                 len = addr->len-sizeof(short);
 364                                 p = &addr->name->sun_path[0];
 365                                 audit_log_format(ab, " path=");
 366                                 if (*p)
 367                                         audit_log_untrustedstring(ab, p);
 368                                 else
 369                                         audit_log_n_hex(ab, p, len);
 370                                 break;
 371                         }
 372                 }
 373
 374                 switch (a->u.net->family) {
 375                 case AF_INET:
 376                         print_ipv4_addr(ab, a->u.net->v4info.saddr,
 377                                         a->u.net->sport,
 378                                         "saddr", "src");
 379                         print_ipv4_addr(ab, a->u.net->v4info.daddr,
 380                                         a->u.net->dport,
 381                                         "daddr", "dest");
 382                         break;
 383                 case AF_INET6:
 384                         print_ipv6_addr(ab, &a->u.net->v6info.saddr,
 385                                         a->u.net->sport,
 386                                         "saddr", "src");
 387                         print_ipv6_addr(ab, &a->u.net->v6info.daddr,
 388                                         a->u.net->dport,
 389                                         "daddr", "dest");
 390                         break;
 391                 }
 392                 if (a->u.net->netif > 0) {
 393                         struct net_device *dev;
 394
 395                         /* NOTE: we always use init's namespace */
 396                         dev = dev_get_by_index(&init_net, a->u.net->netif);
 397                         if (dev) {
 398                                 audit_log_format(ab, " netif=%s", dev->name);
 399                                 dev_put(dev);
 400                         }
 401                 }
 402                 break;
 403 #ifdef CONFIG_KEYS
 404         case LSM_AUDIT_DATA_KEY:
 405                 audit_log_format(ab, " key_serial=%u", a->u.key_struct.key);
 406                 if (a->u.key_struct.key_desc) {
 407                         audit_log_format(ab, " key_desc=");
 408                         audit_log_untrustedstring(ab, a->u.key_struct.key_desc);
 409                 }
 410                 break;
 411 #endif
 412         case LSM_AUDIT_DATA_KMOD:
 413                 audit_log_format(ab, " kmod=");
 414                 audit_log_untrustedstring(ab, a->u.kmod_name);
 415                 break;
 416         case LSM_AUDIT_DATA_IBPKEY: {
 417                 struct in6_addr sbn_pfx;
 418
 419                 memset(&sbn_pfx.s6_addr, 0,
 420                        sizeof(sbn_pfx.s6_addr));
 421                 memcpy(&sbn_pfx.s6_addr, &a->u.ibpkey->subnet_prefix,
 422                        sizeof(a->u.ibpkey->subnet_prefix));
 423                 audit_log_format(ab, " pkey=0x%x subnet_prefix=%pI6c",
 424                                  a->u.ibpkey->pkey, &sbn_pfx);
 425                 break;
 426         }
 427         case LSM_AUDIT_DATA_IBENDPORT:
 428                 audit_log_format(ab, " device=%s port_num=%u",
 429                                  a->u.ibendport->dev_name,
 430                                  a->u.ibendport->port);
 431                 break;
 432         case LSM_AUDIT_DATA_LOCKDOWN:
 433                 audit_log_format(ab, " lockdown_reason=\"%s\"",
 434                                  lockdown_reasons[a->u.reason]);
 435                 break;
 436         } /* switch (a->type) */
 437 }
 438
 439 /**
 440  * common_lsm_audit - generic LSM auditing function
 441  * @a:  auxiliary audit data
 442  * @pre_audit: lsm-specific pre-audit callback
 443  * @post_audit: lsm-specific post-audit callback
 444  *
 445  * setup the audit buffer for common security information
 446  * uses callback to print LSM specific information
 447  */
 448 void common_lsm_audit(struct common_audit_data *a,
 449         void (*pre_audit)(struct audit_buffer *, void *),
 450         void (*post_audit)(struct audit_buffer *, void *))
 451 {
 452         struct audit_buffer *ab;
 453
 454         if (a == NULL)
 455                 return;
 456         /* we use GFP_ATOMIC so we won't sleep */
 457         ab = audit_log_start(audit_context(), GFP_ATOMIC | __GFP_NOWARN,
 458                              AUDIT_AVC);
 459
 460         if (ab == NULL)
 461                 return;
 462
 463         if (pre_audit)
 464                 pre_audit(ab, a);
 465
 466         dump_common_audit_data(ab, a);
 467
 468         if (post_audit)
 469                 post_audit(ab, a);
 470
 471         audit_log_end(ab);
 472 }