linux/security/lsm_audit.c
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   1/*
   2 * common LSM auditing functions
   3 *
   4 * Based on code written for SELinux by :
   5 *                      Stephen Smalley, <sds@epoch.ncsc.mil>
   6 *                      James Morris <jmorris@redhat.com>
   7 * Author : Etienne Basset, <etienne.basset@ensta.org>
   8 *
   9 * This program is free software; you can redistribute it and/or modify
  10 * it under the terms of the GNU General Public License version 2,
  11 * as published by the Free Software Foundation.
  12 */
  13
  14#include <linux/types.h>
  15#include <linux/stddef.h>
  16#include <linux/kernel.h>
  17#include <linux/gfp.h>
  18#include <linux/fs.h>
  19#include <linux/init.h>
  20#include <net/sock.h>
  21#include <linux/un.h>
  22#include <net/af_unix.h>
  23#include <linux/audit.h>
  24#include <linux/ipv6.h>
  25#include <linux/ip.h>
  26#include <net/ip.h>
  27#include <net/ipv6.h>
  28#include <linux/tcp.h>
  29#include <linux/udp.h>
  30#include <linux/dccp.h>
  31#include <linux/sctp.h>
  32#include <linux/lsm_audit.h>
  33
  34/**
  35 * ipv4_skb_to_auditdata : fill auditdata from skb
  36 * @skb : the skb
  37 * @ad : the audit data to fill
  38 * @proto : the layer 4 protocol
  39 *
  40 * return  0 on success
  41 */
  42int ipv4_skb_to_auditdata(struct sk_buff *skb,
  43                struct common_audit_data *ad, u8 *proto)
  44{
  45        int ret = 0;
  46        struct iphdr *ih;
  47
  48        ih = ip_hdr(skb);
  49        if (ih == NULL)
  50                return -EINVAL;
  51
  52        ad->u.net->v4info.saddr = ih->saddr;
  53        ad->u.net->v4info.daddr = ih->daddr;
  54
  55        if (proto)
  56                *proto = ih->protocol;
  57        /* non initial fragment */
  58        if (ntohs(ih->frag_off) & IP_OFFSET)
  59                return 0;
  60
  61        switch (ih->protocol) {
  62        case IPPROTO_TCP: {
  63                struct tcphdr *th = tcp_hdr(skb);
  64                if (th == NULL)
  65                        break;
  66
  67                ad->u.net->sport = th->source;
  68                ad->u.net->dport = th->dest;
  69                break;
  70        }
  71        case IPPROTO_UDP: {
  72                struct udphdr *uh = udp_hdr(skb);
  73                if (uh == NULL)
  74                        break;
  75
  76                ad->u.net->sport = uh->source;
  77                ad->u.net->dport = uh->dest;
  78                break;
  79        }
  80        case IPPROTO_DCCP: {
  81                struct dccp_hdr *dh = dccp_hdr(skb);
  82                if (dh == NULL)
  83                        break;
  84
  85                ad->u.net->sport = dh->dccph_sport;
  86                ad->u.net->dport = dh->dccph_dport;
  87                break;
  88        }
  89        case IPPROTO_SCTP: {
  90                struct sctphdr *sh = sctp_hdr(skb);
  91                if (sh == NULL)
  92                        break;
  93                ad->u.net->sport = sh->source;
  94                ad->u.net->dport = sh->dest;
  95                break;
  96        }
  97        default:
  98                ret = -EINVAL;
  99        }
 100        return ret;
 101}
 102#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
 103/**
 104 * ipv6_skb_to_auditdata : fill auditdata from skb
 105 * @skb : the skb
 106 * @ad : the audit data to fill
 107 * @proto : the layer 4 protocol
 108 *
 109 * return  0 on success
 110 */
 111int ipv6_skb_to_auditdata(struct sk_buff *skb,
 112                struct common_audit_data *ad, u8 *proto)
 113{
 114        int offset, ret = 0;
 115        struct ipv6hdr *ip6;
 116        u8 nexthdr;
 117        __be16 frag_off;
 118
 119        ip6 = ipv6_hdr(skb);
 120        if (ip6 == NULL)
 121                return -EINVAL;
 122        ad->u.net->v6info.saddr = ip6->saddr;
 123        ad->u.net->v6info.daddr = ip6->daddr;
 124        ret = 0;
 125        /* IPv6 can have several extension header before the Transport header
 126         * skip them */
 127        offset = skb_network_offset(skb);
 128        offset += sizeof(*ip6);
 129        nexthdr = ip6->nexthdr;
 130        offset = ipv6_skip_exthdr(skb, offset, &nexthdr, &frag_off);
 131        if (offset < 0)
 132                return 0;
 133        if (proto)
 134                *proto = nexthdr;
 135        switch (nexthdr) {
 136        case IPPROTO_TCP: {
 137                struct tcphdr _tcph, *th;
 138
 139                th = skb_header_pointer(skb, offset, sizeof(_tcph), &_tcph);
 140                if (th == NULL)
 141                        break;
 142
 143                ad->u.net->sport = th->source;
 144                ad->u.net->dport = th->dest;
 145                break;
 146        }
 147        case IPPROTO_UDP: {
 148                struct udphdr _udph, *uh;
 149
 150                uh = skb_header_pointer(skb, offset, sizeof(_udph), &_udph);
 151                if (uh == NULL)
 152                        break;
 153
 154                ad->u.net->sport = uh->source;
 155                ad->u.net->dport = uh->dest;
 156                break;
 157        }
 158        case IPPROTO_DCCP: {
 159                struct dccp_hdr _dccph, *dh;
 160
 161                dh = skb_header_pointer(skb, offset, sizeof(_dccph), &_dccph);
 162                if (dh == NULL)
 163                        break;
 164
 165                ad->u.net->sport = dh->dccph_sport;
 166                ad->u.net->dport = dh->dccph_dport;
 167                break;
 168        }
 169        case IPPROTO_SCTP: {
 170                struct sctphdr _sctph, *sh;
 171
 172                sh = skb_header_pointer(skb, offset, sizeof(_sctph), &_sctph);
 173                if (sh == NULL)
 174                        break;
 175                ad->u.net->sport = sh->source;
 176                ad->u.net->dport = sh->dest;
 177                break;
 178        }
 179        default:
 180                ret = -EINVAL;
 181        }
 182        return ret;
 183}
 184#endif
 185
 186
 187static inline void print_ipv6_addr(struct audit_buffer *ab,
 188                                   struct in6_addr *addr, __be16 port,
 189                                   char *name1, char *name2)
 190{
 191        if (!ipv6_addr_any(addr))
 192                audit_log_format(ab, " %s=%pI6c", name1, addr);
 193        if (port)
 194                audit_log_format(ab, " %s=%d", name2, ntohs(port));
 195}
 196
 197static inline void print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
 198                                   __be16 port, char *name1, char *name2)
 199{
 200        if (addr)
 201                audit_log_format(ab, " %s=%pI4", name1, &addr);
 202        if (port)
 203                audit_log_format(ab, " %s=%d", name2, ntohs(port));
 204}
 205
 206/**
 207 * dump_common_audit_data - helper to dump common audit data
 208 * @a : common audit data
 209 *
 210 */
 211static void dump_common_audit_data(struct audit_buffer *ab,
 212                                   struct common_audit_data *a)
 213{
 214        struct task_struct *tsk = current;
 215
 216        /*
 217         * To keep stack sizes in check force programers to notice if they
 218         * start making this union too large!  See struct lsm_network_audit
 219         * as an example of how to deal with large data.
 220         */
 221        BUILD_BUG_ON(sizeof(a->u) > sizeof(void *)*2);
 222
 223        audit_log_format(ab, " pid=%d comm=", tsk->pid);
 224        audit_log_untrustedstring(ab, tsk->comm);
 225
 226        switch (a->type) {
 227        case LSM_AUDIT_DATA_NONE:
 228                return;
 229        case LSM_AUDIT_DATA_IPC:
 230                audit_log_format(ab, " key=%d ", a->u.ipc_id);
 231                break;
 232        case LSM_AUDIT_DATA_CAP:
 233                audit_log_format(ab, " capability=%d ", a->u.cap);
 234                break;
 235        case LSM_AUDIT_DATA_PATH: {
 236                struct inode *inode;
 237
 238                audit_log_d_path(ab, " path=", &a->u.path);
 239
 240                inode = a->u.path.dentry->d_inode;
 241                if (inode) {
 242                        audit_log_format(ab, " dev=");
 243                        audit_log_untrustedstring(ab, inode->i_sb->s_id);
 244                        audit_log_format(ab, " ino=%lu", inode->i_ino);
 245                }
 246                break;
 247        }
 248        case LSM_AUDIT_DATA_DENTRY: {
 249                struct inode *inode;
 250
 251                audit_log_format(ab, " name=");
 252                audit_log_untrustedstring(ab, a->u.dentry->d_name.name);
 253
 254                inode = a->u.dentry->d_inode;
 255                if (inode) {
 256                        audit_log_format(ab, " dev=");
 257                        audit_log_untrustedstring(ab, inode->i_sb->s_id);
 258                        audit_log_format(ab, " ino=%lu", inode->i_ino);
 259                }
 260                break;
 261        }
 262        case LSM_AUDIT_DATA_INODE: {
 263                struct dentry *dentry;
 264                struct inode *inode;
 265
 266                inode = a->u.inode;
 267                dentry = d_find_alias(inode);
 268                if (dentry) {
 269                        audit_log_format(ab, " name=");
 270                        audit_log_untrustedstring(ab,
 271                                         dentry->d_name.name);
 272                        dput(dentry);
 273                }
 274                audit_log_format(ab, " dev=");
 275                audit_log_untrustedstring(ab, inode->i_sb->s_id);
 276                audit_log_format(ab, " ino=%lu", inode->i_ino);
 277                break;
 278        }
 279        case LSM_AUDIT_DATA_TASK:
 280                tsk = a->u.tsk;
 281                if (tsk && tsk->pid) {
 282                        audit_log_format(ab, " pid=%d comm=", tsk->pid);
 283                        audit_log_untrustedstring(ab, tsk->comm);
 284                }
 285                break;
 286        case LSM_AUDIT_DATA_NET:
 287                if (a->u.net->sk) {
 288                        struct sock *sk = a->u.net->sk;
 289                        struct unix_sock *u;
 290                        int len = 0;
 291                        char *p = NULL;
 292
 293                        switch (sk->sk_family) {
 294                        case AF_INET: {
 295                                struct inet_sock *inet = inet_sk(sk);
 296
 297                                print_ipv4_addr(ab, inet->inet_rcv_saddr,
 298                                                inet->inet_sport,
 299                                                "laddr", "lport");
 300                                print_ipv4_addr(ab, inet->inet_daddr,
 301                                                inet->inet_dport,
 302                                                "faddr", "fport");
 303                                break;
 304                        }
 305                        case AF_INET6: {
 306                                struct inet_sock *inet = inet_sk(sk);
 307                                struct ipv6_pinfo *inet6 = inet6_sk(sk);
 308
 309                                print_ipv6_addr(ab, &inet6->rcv_saddr,
 310                                                inet->inet_sport,
 311                                                "laddr", "lport");
 312                                print_ipv6_addr(ab, &inet6->daddr,
 313                                                inet->inet_dport,
 314                                                "faddr", "fport");
 315                                break;
 316                        }
 317                        case AF_UNIX:
 318                                u = unix_sk(sk);
 319                                if (u->path.dentry) {
 320                                        audit_log_d_path(ab, " path=", &u->path);
 321                                        break;
 322                                }
 323                                if (!u->addr)
 324                                        break;
 325                                len = u->addr->len-sizeof(short);
 326                                p = &u->addr->name->sun_path[0];
 327                                audit_log_format(ab, " path=");
 328                                if (*p)
 329                                        audit_log_untrustedstring(ab, p);
 330                                else
 331                                        audit_log_n_hex(ab, p, len);
 332                                break;
 333                        }
 334                }
 335
 336                switch (a->u.net->family) {
 337                case AF_INET:
 338                        print_ipv4_addr(ab, a->u.net->v4info.saddr,
 339                                        a->u.net->sport,
 340                                        "saddr", "src");
 341                        print_ipv4_addr(ab, a->u.net->v4info.daddr,
 342                                        a->u.net->dport,
 343                                        "daddr", "dest");
 344                        break;
 345                case AF_INET6:
 346                        print_ipv6_addr(ab, &a->u.net->v6info.saddr,
 347                                        a->u.net->sport,
 348                                        "saddr", "src");
 349                        print_ipv6_addr(ab, &a->u.net->v6info.daddr,
 350                                        a->u.net->dport,
 351                                        "daddr", "dest");
 352                        break;
 353                }
 354                if (a->u.net->netif > 0) {
 355                        struct net_device *dev;
 356
 357                        /* NOTE: we always use init's namespace */
 358                        dev = dev_get_by_index(&init_net, a->u.net->netif);
 359                        if (dev) {
 360                                audit_log_format(ab, " netif=%s", dev->name);
 361                                dev_put(dev);
 362                        }
 363                }
 364                break;
 365#ifdef CONFIG_KEYS
 366        case LSM_AUDIT_DATA_KEY:
 367                audit_log_format(ab, " key_serial=%u", a->u.key_struct.key);
 368                if (a->u.key_struct.key_desc) {
 369                        audit_log_format(ab, " key_desc=");
 370                        audit_log_untrustedstring(ab, a->u.key_struct.key_desc);
 371                }
 372                break;
 373#endif
 374        case LSM_AUDIT_DATA_KMOD:
 375                audit_log_format(ab, " kmod=");
 376                audit_log_untrustedstring(ab, a->u.kmod_name);
 377                break;
 378        } /* switch (a->type) */
 379}
 380
 381/**
 382 * common_lsm_audit - generic LSM auditing function
 383 * @a:  auxiliary audit data
 384 * @pre_audit: lsm-specific pre-audit callback
 385 * @post_audit: lsm-specific post-audit callback
 386 *
 387 * setup the audit buffer for common security information
 388 * uses callback to print LSM specific information
 389 */
 390void common_lsm_audit(struct common_audit_data *a,
 391        void (*pre_audit)(struct audit_buffer *, void *),
 392        void (*post_audit)(struct audit_buffer *, void *))
 393{
 394        struct audit_buffer *ab;
 395
 396        if (a == NULL)
 397                return;
 398        /* we use GFP_ATOMIC so we won't sleep */
 399        ab = audit_log_start(current->audit_context, GFP_ATOMIC, AUDIT_AVC);
 400
 401        if (ab == NULL)
 402                return;
 403
 404        if (pre_audit)
 405                pre_audit(ab, a);
 406
 407        dump_common_audit_data(ab, a);
 408
 409        if (post_audit)
 410                post_audit(ab, a);
 411
 412        audit_log_end(ab);
 413}
 414
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