linux/security/lsm_audit.c
<<
>>
Prefs
   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 */
  40int 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        ad->u.net->v4info.saddr = ih->saddr;
  48        ad->u.net->v4info.daddr = ih->daddr;
  49
  50        if (proto)
  51                *proto = ih->protocol;
  52        /* non initial fragment */
  53        if (ntohs(ih->frag_off) & IP_OFFSET)
  54                return 0;
  55
  56        switch (ih->protocol) {
  57        case IPPROTO_TCP: {
  58                struct tcphdr *th = tcp_hdr(skb);
  59
  60                ad->u.net->sport = th->source;
  61                ad->u.net->dport = th->dest;
  62                break;
  63        }
  64        case IPPROTO_UDP: {
  65                struct udphdr *uh = udp_hdr(skb);
  66
  67                ad->u.net->sport = uh->source;
  68                ad->u.net->dport = uh->dest;
  69                break;
  70        }
  71        case IPPROTO_DCCP: {
  72                struct dccp_hdr *dh = dccp_hdr(skb);
  73
  74                ad->u.net->sport = dh->dccph_sport;
  75                ad->u.net->dport = dh->dccph_dport;
  76                break;
  77        }
  78        case IPPROTO_SCTP: {
  79                struct sctphdr *sh = sctp_hdr(skb);
  80
  81                ad->u.net->sport = sh->source;
  82                ad->u.net->dport = sh->dest;
  83                break;
  84        }
  85        default:
  86                ret = -EINVAL;
  87        }
  88        return ret;
  89}
  90#if IS_ENABLED(CONFIG_IPV6)
  91/**
  92 * ipv6_skb_to_auditdata : fill auditdata from skb
  93 * @skb : the skb
  94 * @ad : the audit data to fill
  95 * @proto : the layer 4 protocol
  96 *
  97 * return  0 on success
  98 */
  99int ipv6_skb_to_auditdata(struct sk_buff *skb,
 100                struct common_audit_data *ad, u8 *proto)
 101{
 102        int offset, ret = 0;
 103        struct ipv6hdr *ip6;
 104        u8 nexthdr;
 105        __be16 frag_off;
 106
 107        ip6 = ipv6_hdr(skb);
 108        ad->u.net->v6info.saddr = ip6->saddr;
 109        ad->u.net->v6info.daddr = ip6->daddr;
 110        /* IPv6 can have several extension header before the Transport header
 111         * skip them */
 112        offset = skb_network_offset(skb);
 113        offset += sizeof(*ip6);
 114        nexthdr = ip6->nexthdr;
 115        offset = ipv6_skip_exthdr(skb, offset, &nexthdr, &frag_off);
 116        if (offset < 0)
 117                return 0;
 118        if (proto)
 119                *proto = nexthdr;
 120        switch (nexthdr) {
 121        case IPPROTO_TCP: {
 122                struct tcphdr _tcph, *th;
 123
 124                th = skb_header_pointer(skb, offset, sizeof(_tcph), &_tcph);
 125                if (th == NULL)
 126                        break;
 127
 128                ad->u.net->sport = th->source;
 129                ad->u.net->dport = th->dest;
 130                break;
 131        }
 132        case IPPROTO_UDP: {
 133                struct udphdr _udph, *uh;
 134
 135                uh = skb_header_pointer(skb, offset, sizeof(_udph), &_udph);
 136                if (uh == NULL)
 137                        break;
 138
 139                ad->u.net->sport = uh->source;
 140                ad->u.net->dport = uh->dest;
 141                break;
 142        }
 143        case IPPROTO_DCCP: {
 144                struct dccp_hdr _dccph, *dh;
 145
 146                dh = skb_header_pointer(skb, offset, sizeof(_dccph), &_dccph);
 147                if (dh == NULL)
 148                        break;
 149
 150                ad->u.net->sport = dh->dccph_sport;
 151                ad->u.net->dport = dh->dccph_dport;
 152                break;
 153        }
 154        case IPPROTO_SCTP: {
 155                struct sctphdr _sctph, *sh;
 156
 157                sh = skb_header_pointer(skb, offset, sizeof(_sctph), &_sctph);
 158                if (sh == NULL)
 159                        break;
 160                ad->u.net->sport = sh->source;
 161                ad->u.net->dport = sh->dest;
 162                break;
 163        }
 164        default:
 165                ret = -EINVAL;
 166        }
 167        return ret;
 168}
 169#endif
 170
 171
 172static inline void print_ipv6_addr(struct audit_buffer *ab,
 173                                   const struct in6_addr *addr, __be16 port,
 174                                   char *name1, char *name2)
 175{
 176        if (!ipv6_addr_any(addr))
 177                audit_log_format(ab, " %s=%pI6c", name1, addr);
 178        if (port)
 179                audit_log_format(ab, " %s=%d", name2, ntohs(port));
 180}
 181
 182static inline void print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
 183                                   __be16 port, char *name1, char *name2)
 184{
 185        if (addr)
 186                audit_log_format(ab, " %s=%pI4", name1, &addr);
 187        if (port)
 188                audit_log_format(ab, " %s=%d", name2, ntohs(port));
 189}
 190
 191/**
 192 * dump_common_audit_data - helper to dump common audit data
 193 * @ab : the audit buffer
 194 * @a : common audit data
 195 *
 196 */
 197static void dump_common_audit_data(struct audit_buffer *ab,
 198                                   struct common_audit_data *a)
 199{
 200        char comm[sizeof(current->comm)];
 201
 202        /*
 203         * To keep stack sizes in check force programmers to notice if they
 204         * start making this union too large!  See struct lsm_network_audit
 205         * as an example of how to deal with large data.
 206         */
 207        BUILD_BUG_ON(sizeof(a->u) > sizeof(void *)*2);
 208
 209        audit_log_format(ab, " pid=%d comm=", task_tgid_nr(current));
 210        audit_log_untrustedstring(ab, memcpy(comm, current->comm, sizeof(comm)));
 211
 212        switch (a->type) {
 213        case LSM_AUDIT_DATA_NONE:
 214                return;
 215        case LSM_AUDIT_DATA_IPC:
 216                audit_log_format(ab, " ipc_key=%d ", a->u.ipc_id);
 217                break;
 218        case LSM_AUDIT_DATA_CAP:
 219                audit_log_format(ab, " capability=%d ", a->u.cap);
 220                break;
 221        case LSM_AUDIT_DATA_PATH: {
 222                struct inode *inode;
 223
 224                audit_log_d_path(ab, " path=", &a->u.path);
 225
 226                inode = d_backing_inode(a->u.path.dentry);
 227                if (inode) {
 228                        audit_log_format(ab, " dev=");
 229                        audit_log_untrustedstring(ab, inode->i_sb->s_id);
 230                        audit_log_format(ab, " ino=%lu", inode->i_ino);
 231                }
 232                break;
 233        }
 234        case LSM_AUDIT_DATA_FILE: {
 235                struct inode *inode;
 236
 237                audit_log_d_path(ab, " path=", &a->u.file->f_path);
 238
 239                inode = file_inode(a->u.file);
 240                if (inode) {
 241                        audit_log_format(ab, " dev=");
 242                        audit_log_untrustedstring(ab, inode->i_sb->s_id);
 243                        audit_log_format(ab, " ino=%lu", inode->i_ino);
 244                }
 245                break;
 246        }
 247        case LSM_AUDIT_DATA_IOCTL_OP: {
 248                struct inode *inode;
 249
 250                audit_log_d_path(ab, " path=", &a->u.op->path);
 251
 252                inode = a->u.op->path.dentry->d_inode;
 253                if (inode) {
 254                        audit_log_format(ab, " dev=");
 255                        audit_log_untrustedstring(ab, inode->i_sb->s_id);
 256                        audit_log_format(ab, " ino=%lu", inode->i_ino);
 257                }
 258
 259                audit_log_format(ab, " ioctlcmd=0x%hx", a->u.op->cmd);
 260                break;
 261        }
 262        case LSM_AUDIT_DATA_DENTRY: {
 263                struct inode *inode;
 264
 265                audit_log_format(ab, " name=");
 266                spin_lock(&a->u.dentry->d_lock);
 267                audit_log_untrustedstring(ab, a->u.dentry->d_name.name);
 268                spin_unlock(&a->u.dentry->d_lock);
 269
 270                inode = d_backing_inode(a->u.dentry);
 271                if (inode) {
 272                        audit_log_format(ab, " dev=");
 273                        audit_log_untrustedstring(ab, inode->i_sb->s_id);
 274                        audit_log_format(ab, " ino=%lu", inode->i_ino);
 275                }
 276                break;
 277        }
 278        case LSM_AUDIT_DATA_INODE: {
 279                struct dentry *dentry;
 280                struct inode *inode;
 281
 282                rcu_read_lock();
 283                inode = a->u.inode;
 284                dentry = d_find_alias_rcu(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                }
 291                audit_log_format(ab, " dev=");
 292                audit_log_untrustedstring(ab, inode->i_sb->s_id);
 293                audit_log_format(ab, " ino=%lu", inode->i_ino);
 294                rcu_read_unlock();
 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_tgid_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                        const struct sock *sk = a->u.net->sk;
 313                        const 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                                const 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                                const 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        case LSM_AUDIT_DATA_IBPKEY: {
 406                struct in6_addr sbn_pfx;
 407
 408                memset(&sbn_pfx.s6_addr, 0,
 409                       sizeof(sbn_pfx.s6_addr));
 410                memcpy(&sbn_pfx.s6_addr, &a->u.ibpkey->subnet_prefix,
 411                       sizeof(a->u.ibpkey->subnet_prefix));
 412                audit_log_format(ab, " pkey=0x%x subnet_prefix=%pI6c",
 413                                 a->u.ibpkey->pkey, &sbn_pfx);
 414                break;
 415        }
 416        case LSM_AUDIT_DATA_IBENDPORT:
 417                audit_log_format(ab, " device=%s port_num=%u",
 418                                 a->u.ibendport->dev_name,
 419                                 a->u.ibendport->port);
 420                break;
 421        case LSM_AUDIT_DATA_LOCKDOWN:
 422                audit_log_format(ab, " lockdown_reason=\"%s\"",
 423                                 lockdown_reasons[a->u.reason]);
 424                break;
 425        case LSM_AUDIT_DATA_ANONINODE:
 426                audit_log_format(ab, " anonclass=%s", a->u.anonclass);
 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 */
 440void 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}
 465