linux/security/lsm_audit.c
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   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        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 */
 109int 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
 184static 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
 194static 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 */
 208static 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                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 */
 448void 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}
 473