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/fs.h>
  18#include <linux/init.h>
  19#include <net/sock.h>
  20#include <linux/un.h>
  21#include <net/af_unix.h>
  22#include <linux/audit.h>
  23#include <linux/ipv6.h>
  24#include <linux/ip.h>
  25#include <net/ip.h>
  26#include <net/ipv6.h>
  27#include <linux/tcp.h>
  28#include <linux/udp.h>
  29#include <linux/dccp.h>
  30#include <linux/sctp.h>
  31#include <linux/lsm_audit.h>
  32
  33/**
  34 * ipv4_skb_to_auditdata : fill auditdata from skb
  35 * @skb : the skb
  36 * @ad : the audit data to fill
  37 * @proto : the layer 4 protocol
  38 *
  39 * return  0 on success
  40 */
  41int ipv4_skb_to_auditdata(struct sk_buff *skb,
  42                struct common_audit_data *ad, u8 *proto)
  43{
  44        int ret = 0;
  45        struct iphdr *ih;
  46
  47        ih = ip_hdr(skb);
  48        if (ih == NULL)
  49                return -EINVAL;
  50
  51        ad->u.net.v4info.saddr = ih->saddr;
  52        ad->u.net.v4info.daddr = ih->daddr;
  53
  54        if (proto)
  55                *proto = ih->protocol;
  56        /* non initial fragment */
  57        if (ntohs(ih->frag_off) & IP_OFFSET)
  58                return 0;
  59
  60        switch (ih->protocol) {
  61        case IPPROTO_TCP: {
  62                struct tcphdr *th = tcp_hdr(skb);
  63                if (th == NULL)
  64                        break;
  65
  66                ad->u.net.sport = th->source;
  67                ad->u.net.dport = th->dest;
  68                break;
  69        }
  70        case IPPROTO_UDP: {
  71                struct udphdr *uh = udp_hdr(skb);
  72                if (uh == NULL)
  73                        break;
  74
  75                ad->u.net.sport = uh->source;
  76                ad->u.net.dport = uh->dest;
  77                break;
  78        }
  79        case IPPROTO_DCCP: {
  80                struct dccp_hdr *dh = dccp_hdr(skb);
  81                if (dh == NULL)
  82                        break;
  83
  84                ad->u.net.sport = dh->dccph_sport;
  85                ad->u.net.dport = dh->dccph_dport;
  86                break;
  87        }
  88        case IPPROTO_SCTP: {
  89                struct sctphdr *sh = sctp_hdr(skb);
  90                if (sh == NULL)
  91                        break;
  92                ad->u.net.sport = sh->source;
  93                ad->u.net.dport = sh->dest;
  94                break;
  95        }
  96        default:
  97                ret = -EINVAL;
  98        }
  99        return ret;
 100}
 101#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
 102/**
 103 * ipv6_skb_to_auditdata : fill auditdata from skb
 104 * @skb : the skb
 105 * @ad : the audit data to fill
 106 * @proto : the layer 4 protocol
 107 *
 108 * return  0 on success
 109 */
 110int ipv6_skb_to_auditdata(struct sk_buff *skb,
 111                struct common_audit_data *ad, u8 *proto)
 112{
 113        int offset, ret = 0;
 114        struct ipv6hdr *ip6;
 115        u8 nexthdr;
 116
 117        ip6 = ipv6_hdr(skb);
 118        if (ip6 == NULL)
 119                return -EINVAL;
 120        ipv6_addr_copy(&ad->u.net.v6info.saddr, &ip6->saddr);
 121        ipv6_addr_copy(&ad->u.net.v6info.daddr, &ip6->daddr);
 122        ret = 0;
 123        /* IPv6 can have several extension header before the Transport header
 124         * skip them */
 125        offset = skb_network_offset(skb);
 126        offset += sizeof(*ip6);
 127        nexthdr = ip6->nexthdr;
 128        offset = ipv6_skip_exthdr(skb, offset, &nexthdr);
 129        if (offset < 0)
 130                return 0;
 131        if (proto)
 132                *proto = nexthdr;
 133        switch (nexthdr) {
 134        case IPPROTO_TCP: {
 135                struct tcphdr _tcph, *th;
 136
 137                th = skb_header_pointer(skb, offset, sizeof(_tcph), &_tcph);
 138                if (th == NULL)
 139                        break;
 140
 141                ad->u.net.sport = th->source;
 142                ad->u.net.dport = th->dest;
 143                break;
 144        }
 145        case IPPROTO_UDP: {
 146                struct udphdr _udph, *uh;
 147
 148                uh = skb_header_pointer(skb, offset, sizeof(_udph), &_udph);
 149                if (uh == NULL)
 150                        break;
 151
 152                ad->u.net.sport = uh->source;
 153                ad->u.net.dport = uh->dest;
 154                break;
 155        }
 156        case IPPROTO_DCCP: {
 157                struct dccp_hdr _dccph, *dh;
 158
 159                dh = skb_header_pointer(skb, offset, sizeof(_dccph), &_dccph);
 160                if (dh == NULL)
 161                        break;
 162
 163                ad->u.net.sport = dh->dccph_sport;
 164                ad->u.net.dport = dh->dccph_dport;
 165                break;
 166        }
 167        case IPPROTO_SCTP: {
 168                struct sctphdr _sctph, *sh;
 169
 170                sh = skb_header_pointer(skb, offset, sizeof(_sctph), &_sctph);
 171                if (sh == NULL)
 172                        break;
 173                ad->u.net.sport = sh->source;
 174                ad->u.net.dport = sh->dest;
 175                break;
 176        }
 177        default:
 178                ret = -EINVAL;
 179        }
 180        return ret;
 181}
 182#endif
 183
 184
 185static inline void print_ipv6_addr(struct audit_buffer *ab,
 186                                   struct in6_addr *addr, __be16 port,
 187                                   char *name1, char *name2)
 188{
 189        if (!ipv6_addr_any(addr))
 190                audit_log_format(ab, " %s=%pI6c", name1, addr);
 191        if (port)
 192                audit_log_format(ab, " %s=%d", name2, ntohs(port));
 193}
 194
 195static inline void print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
 196                                   __be16 port, char *name1, char *name2)
 197{
 198        if (addr)
 199                audit_log_format(ab, " %s=%pI4", name1, &addr);
 200        if (port)
 201                audit_log_format(ab, " %s=%d", name2, ntohs(port));
 202}
 203
 204/**
 205 * dump_common_audit_data - helper to dump common audit data
 206 * @a : common audit data
 207 *
 208 */
 209static void dump_common_audit_data(struct audit_buffer *ab,
 210                                   struct common_audit_data *a)
 211{
 212        struct inode *inode = NULL;
 213        struct task_struct *tsk = current;
 214
 215        if (a->tsk)
 216                tsk = a->tsk;
 217        if (tsk && tsk->pid) {
 218                audit_log_format(ab, " pid=%d comm=", tsk->pid);
 219                audit_log_untrustedstring(ab, tsk->comm);
 220        }
 221
 222        switch (a->type) {
 223        case LSM_AUDIT_NO_AUDIT:
 224                return;
 225        case LSM_AUDIT_DATA_IPC:
 226                audit_log_format(ab, " key=%d ", a->u.ipc_id);
 227                break;
 228        case LSM_AUDIT_DATA_CAP:
 229                audit_log_format(ab, " capability=%d ", a->u.cap);
 230                break;
 231        case LSM_AUDIT_DATA_FS:
 232                if (a->u.fs.path.dentry) {
 233                        struct dentry *dentry = a->u.fs.path.dentry;
 234                        if (a->u.fs.path.mnt) {
 235                                audit_log_d_path(ab, "path=", &a->u.fs.path);
 236                        } else {
 237                                audit_log_format(ab, " name=");
 238                                audit_log_untrustedstring(ab,
 239                                                 dentry->d_name.name);
 240                        }
 241                        inode = dentry->d_inode;
 242                } else if (a->u.fs.inode) {
 243                        struct dentry *dentry;
 244                        inode = a->u.fs.inode;
 245                        dentry = d_find_alias(inode);
 246                        if (dentry) {
 247                                audit_log_format(ab, " name=");
 248                                audit_log_untrustedstring(ab,
 249                                                 dentry->d_name.name);
 250                                dput(dentry);
 251                        }
 252                }
 253                if (inode)
 254                        audit_log_format(ab, " dev=%s ino=%lu",
 255                                        inode->i_sb->s_id,
 256                                        inode->i_ino);
 257                break;
 258        case LSM_AUDIT_DATA_TASK:
 259                tsk = a->u.tsk;
 260                if (tsk && tsk->pid) {
 261                        audit_log_format(ab, " pid=%d comm=", tsk->pid);
 262                        audit_log_untrustedstring(ab, tsk->comm);
 263                }
 264                break;
 265        case LSM_AUDIT_DATA_NET:
 266                if (a->u.net.sk) {
 267                        struct sock *sk = a->u.net.sk;
 268                        struct unix_sock *u;
 269                        int len = 0;
 270                        char *p = NULL;
 271
 272                        switch (sk->sk_family) {
 273                        case AF_INET: {
 274                                struct inet_sock *inet = inet_sk(sk);
 275
 276                                print_ipv4_addr(ab, inet->rcv_saddr,
 277                                                inet->sport,
 278                                                "laddr", "lport");
 279                                print_ipv4_addr(ab, inet->daddr,
 280                                                inet->dport,
 281                                                "faddr", "fport");
 282                                break;
 283                        }
 284                        case AF_INET6: {
 285                                struct inet_sock *inet = inet_sk(sk);
 286                                struct ipv6_pinfo *inet6 = inet6_sk(sk);
 287
 288                                print_ipv6_addr(ab, &inet6->rcv_saddr,
 289                                                inet->sport,
 290                                                "laddr", "lport");
 291                                print_ipv6_addr(ab, &inet6->daddr,
 292                                                inet->dport,
 293                                                "faddr", "fport");
 294                                break;
 295                        }
 296                        case AF_UNIX:
 297                                u = unix_sk(sk);
 298                                if (u->dentry) {
 299                                        struct path path = {
 300                                                .dentry = u->dentry,
 301                                                .mnt = u->mnt
 302                                        };
 303                                        audit_log_d_path(ab, "path=", &path);
 304                                        break;
 305                                }
 306                                if (!u->addr)
 307                                        break;
 308                                len = u->addr->len-sizeof(short);
 309                                p = &u->addr->name->sun_path[0];
 310                                audit_log_format(ab, " path=");
 311                                if (*p)
 312                                        audit_log_untrustedstring(ab, p);
 313                                else
 314                                        audit_log_n_hex(ab, p, len);
 315                                break;
 316                        }
 317                }
 318
 319                switch (a->u.net.family) {
 320                case AF_INET:
 321                        print_ipv4_addr(ab, a->u.net.v4info.saddr,
 322                                        a->u.net.sport,
 323                                        "saddr", "src");
 324                        print_ipv4_addr(ab, a->u.net.v4info.daddr,
 325                                        a->u.net.dport,
 326                                        "daddr", "dest");
 327                        break;
 328                case AF_INET6:
 329                        print_ipv6_addr(ab, &a->u.net.v6info.saddr,
 330                                        a->u.net.sport,
 331                                        "saddr", "src");
 332                        print_ipv6_addr(ab, &a->u.net.v6info.daddr,
 333                                        a->u.net.dport,
 334                                        "daddr", "dest");
 335                        break;
 336                }
 337                if (a->u.net.netif > 0) {
 338                        struct net_device *dev;
 339
 340                        /* NOTE: we always use init's namespace */
 341                        dev = dev_get_by_index(&init_net, a->u.net.netif);
 342                        if (dev) {
 343                                audit_log_format(ab, " netif=%s", dev->name);
 344                                dev_put(dev);
 345                        }
 346                }
 347                break;
 348#ifdef CONFIG_KEYS
 349        case LSM_AUDIT_DATA_KEY:
 350                audit_log_format(ab, " key_serial=%u", a->u.key_struct.key);
 351                if (a->u.key_struct.key_desc) {
 352                        audit_log_format(ab, " key_desc=");
 353                        audit_log_untrustedstring(ab, a->u.key_struct.key_desc);
 354                }
 355                break;
 356#endif
 357        } /* switch (a->type) */
 358}
 359
 360/**
 361 * common_lsm_audit - generic LSM auditing function
 362 * @a:  auxiliary audit data
 363 *
 364 * setup the audit buffer for common security information
 365 * uses callback to print LSM specific information
 366 */
 367void common_lsm_audit(struct common_audit_data *a)
 368{
 369        struct audit_buffer *ab;
 370
 371        if (a == NULL)
 372                return;
 373        /* we use GFP_ATOMIC so we won't sleep */
 374        ab = audit_log_start(current->audit_context, GFP_ATOMIC, AUDIT_AVC);
 375
 376        if (ab == NULL)
 377                return;
 378
 379        if (a->lsm_pre_audit)
 380                a->lsm_pre_audit(ab, a);
 381
 382        dump_common_audit_data(ab, a);
 383
 384        if (a->lsm_post_audit)
 385                a->lsm_post_audit(ab, a);
 386
 387        audit_log_end(ab);
 388}
 389