src/lxc/lsm/apparmor.c

   1 /* apparmor
   2  *
   3  * Copyright © 2012 Serge Hallyn <serge.hallyn@ubuntu.com>.
   4  * Copyright © 2012 Canonical Ltd.
   5  *
   6  *  This library is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU Lesser General Public
   8  *  License as published by the Free Software Foundation; either
   9  *  version 2.1 of the License, or (at your option) any later version.
  10
  11  *  This library is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  *  Lesser General Public License for more details.
  15
  16  *  You should have received a copy of the GNU Lesser General Public
  17  *  License along with this library; if not, write to the Free Software
  18  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  19  */
  20
  21 #ifndef _GNU_SOURCE
  22 #define _GNU_SOURCE 1
  23 #endif
  24 #include <errno.h>
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <sys/mount.h>
  28 #include <sys/stat.h>
  29 #include <sys/types.h>
  30 #include <sys/vfs.h>
  31 #include <unistd.h>
  32
  33 #include "caps.h"
  34 #include "conf.h"
  35 #include "config.h"
  36 #include "initutils.h"
  37 #include "log.h"
  38 #include "lsm.h"
  39 #include "parse.h"
  40 #include "utils.h"
  41
  42 lxc_log_define(apparmor, lsm);
  43
  44 /* set by lsm_apparmor_drv_init if true */
  45 static int aa_enabled = 0;
  46 static bool aa_parser_available = false;
  47 static bool aa_supports_unix = false;
  48 static bool aa_can_stack = false;
  49 static bool aa_is_stacked = false;
  50 static bool aa_admin = false;
  51
  52 static int mount_features_enabled = 0;
  53
  54 #define AA_DEF_PROFILE "lxc-container-default"
  55 #define AA_DEF_PROFILE_CGNS "lxc-container-default-cgns"
  56 #define AA_MOUNT_RESTR "/sys/kernel/security/apparmor/features/mount/mask"
  57 #define AA_ENABLED_FILE "/sys/module/apparmor/parameters/enabled"
  58 #define AA_UNCHANGED "unchanged"
  59 #define AA_GENERATED "generated"
  60
  61 #define AA_CMD_LOAD   'r'
  62 #define AA_CMD_UNLOAD 'R'
  63 #define AA_CMD_PARSE  'Q'
  64
  65 static const char AA_PROFILE_BASE[] =
  66 "  ### Base profile\n"
  67 "  capability,\n"
  68 "  dbus,\n"
  69 "  file,\n"
  70 "  network,\n"
  71 "  umount,\n"
  72 "\n"
  73 "  # Allow us to receive signals from anywhere.\n"
  74 "  signal (receive),\n"
  75 "\n"
  76 "  # Allow us to send signals to ourselves\n"
  77 "  signal peer=@{profile_name},\n"
  78 "\n"
  79 "  # Allow other processes to read our /proc entries, futexes, perf tracing and\n"
  80 "  # kcmp for now (they will need 'read' in the first place). Administrators can\n"
  81 "  # override with:\n"
  82 "  #   deny ptrace (readby) ...\n"
  83 "  ptrace (readby),\n"
  84 "\n"
  85 "  # Allow other processes to trace us by default (they will need 'trace' in\n"
  86 "  # the first place). Administrators can override with:\n"
  87 "  #   deny ptrace (tracedby) ...\n"
  88 "  ptrace (tracedby),\n"
  89 "\n"
  90 "  # Allow us to ptrace ourselves\n"
  91 "  ptrace peer=@{profile_name},\n"
  92 "\n"
  93 "  # ignore DENIED message on / remount\n"
  94 "  deny mount options=(ro, remount) -> /,\n"
  95 "  deny mount options=(ro, remount, silent) -> /,\n"
  96 "\n"
  97 "  # allow tmpfs mounts everywhere\n"
  98 "  mount fstype=tmpfs,\n"
  99 "\n"
 100 "  # allow hugetlbfs mounts everywhere\n"
 101 "  mount fstype=hugetlbfs,\n"
 102 "\n"
 103 "  # allow mqueue mounts everywhere\n"
 104 "  mount fstype=mqueue,\n"
 105 "\n"
 106 "  # allow fuse mounts everywhere\n"
 107 "  mount fstype=fuse,\n"
 108 "  mount fstype=fuse.*,\n"
 109 "\n"
 110 "  # deny access under /proc/bus to avoid e.g. messing with pci devices directly\n"
 111 "  deny @{PROC}/bus/** wklx,\n"
 112 "\n"
 113 "  # deny writes in /proc/sys/fs but allow binfmt_misc to be mounted\n"
 114 "  mount fstype=binfmt_misc -> /proc/sys/fs/binfmt_misc/,\n"
 115 "  deny @{PROC}/sys/fs/** wklx,\n"
 116 "\n"
 117 "  # allow efivars to be mounted, writing to it will be blocked though\n"
 118 "  mount fstype=efivarfs -> /sys/firmware/efi/efivars/,\n"
 119 "\n"
 120 "  # block some other dangerous paths\n"
 121 "  deny @{PROC}/kcore rwklx,\n"
 122 "  deny @{PROC}/sysrq-trigger rwklx,\n"
 123 "\n"
 124 "  # deny writes in /sys except for /sys/fs/cgroup, also allow\n"
 125 "  # fusectl, securityfs and debugfs to be mounted there (read-only)\n"
 126 "  mount fstype=fusectl -> /sys/fs/fuse/connections/,\n"
 127 "  mount fstype=securityfs -> /sys/kernel/security/,\n"
 128 "  mount fstype=debugfs -> /sys/kernel/debug/,\n"
 129 "  deny mount fstype=debugfs -> /var/lib/ureadahead/debugfs/,\n"
 130 "  mount fstype=proc -> /proc/,\n"
 131 "  mount fstype=sysfs -> /sys/,\n"
 132 "  mount options=(rw, nosuid, nodev, noexec, remount) -> /sys/,\n"
 133 "  deny /sys/firmware/efi/efivars/** rwklx,\n"
 134 "  # note, /sys/kernel/security/** handled below\n"
 135 "  mount options=(ro, nosuid, nodev, noexec, remount, strictatime) -> /sys/fs/cgroup/,\n"
 136 "\n"
 137 "  # deny reads from debugfs\n"
 138 "  deny /sys/kernel/debug/{,**} rwklx,\n"
 139 "\n"
 140 "  # allow paths to be made slave, shared, private or unbindable\n"
 141 "  # FIXME: This currently doesn't work due to the apparmor parser treating those as allowing all mounts.\n"
 142 "#  mount options=(rw,make-slave) -> **,\n"
 143 "#  mount options=(rw,make-rslave) -> **,\n"
 144 "#  mount options=(rw,make-shared) -> **,\n"
 145 "#  mount options=(rw,make-rshared) -> **,\n"
 146 "#  mount options=(rw,make-private) -> **,\n"
 147 "#  mount options=(rw,make-rprivate) -> **,\n"
 148 "#  mount options=(rw,make-unbindable) -> **,\n"
 149 "#  mount options=(rw,make-runbindable) -> **,\n"
 150 "\n"
 151 "  # allow bind-mounts of anything except /proc, /sys and /dev\n"
 152 "  mount options=(rw,bind) /[^spd]*{,/**},\n"
 153 "  mount options=(rw,bind) /d[^e]*{,/**},\n"
 154 "  mount options=(rw,bind) /de[^v]*{,/**},\n"
 155 "  mount options=(rw,bind) /dev/.[^l]*{,/**},\n"
 156 "  mount options=(rw,bind) /dev/.l[^x]*{,/**},\n"
 157 "  mount options=(rw,bind) /dev/.lx[^c]*{,/**},\n"
 158 "  mount options=(rw,bind) /dev/.lxc?*{,/**},\n"
 159 "  mount options=(rw,bind) /dev/[^.]*{,/**},\n"
 160 "  mount options=(rw,bind) /dev?*{,/**},\n"
 161 "  mount options=(rw,bind) /p[^r]*{,/**},\n"
 162 "  mount options=(rw,bind) /pr[^o]*{,/**},\n"
 163 "  mount options=(rw,bind) /pro[^c]*{,/**},\n"
 164 "  mount options=(rw,bind) /proc?*{,/**},\n"
 165 "  mount options=(rw,bind) /s[^y]*{,/**},\n"
 166 "  mount options=(rw,bind) /sy[^s]*{,/**},\n"
 167 "  mount options=(rw,bind) /sys?*{,/**},\n"
 168 "\n"
 169 "  # allow read-only bind-mounts of anything except /proc, /sys and /dev\n"
 170 "  mount options=(ro,remount,bind) -> /[^spd]*{,/**},\n"
 171 "  mount options=(ro,remount,bind) -> /d[^e]*{,/**},\n"
 172 "  mount options=(ro,remount,bind) -> /de[^v]*{,/**},\n"
 173 "  mount options=(ro,remount,bind) -> /dev/.[^l]*{,/**},\n"
 174 "  mount options=(ro,remount,bind) -> /dev/.l[^x]*{,/**},\n"
 175 "  mount options=(ro,remount,bind) -> /dev/.lx[^c]*{,/**},\n"
 176 "  mount options=(ro,remount,bind) -> /dev/.lxc?*{,/**},\n"
 177 "  mount options=(ro,remount,bind) -> /dev/[^.]*{,/**},\n"
 178 "  mount options=(ro,remount,bind) -> /dev?*{,/**},\n"
 179 "  mount options=(ro,remount,bind) -> /p[^r]*{,/**},\n"
 180 "  mount options=(ro,remount,bind) -> /pr[^o]*{,/**},\n"
 181 "  mount options=(ro,remount,bind) -> /pro[^c]*{,/**},\n"
 182 "  mount options=(ro,remount,bind) -> /proc?*{,/**},\n"
 183 "  mount options=(ro,remount,bind) -> /s[^y]*{,/**},\n"
 184 "  mount options=(ro,remount,bind) -> /sy[^s]*{,/**},\n"
 185 "  mount options=(ro,remount,bind) -> /sys?*{,/**},\n"
 186 "\n"
 187 "  # allow moving mounts except for /proc, /sys and /dev\n"
 188 "  mount options=(rw,move) /[^spd]*{,/**},\n"
 189 "  mount options=(rw,move) /d[^e]*{,/**},\n"
 190 "  mount options=(rw,move) /de[^v]*{,/**},\n"
 191 "  mount options=(rw,move) /dev/.[^l]*{,/**},\n"
 192 "  mount options=(rw,move) /dev/.l[^x]*{,/**},\n"
 193 "  mount options=(rw,move) /dev/.lx[^c]*{,/**},\n"
 194 "  mount options=(rw,move) /dev/.lxc?*{,/**},\n"
 195 "  mount options=(rw,move) /dev/[^.]*{,/**},\n"
 196 "  mount options=(rw,move) /dev?*{,/**},\n"
 197 "  mount options=(rw,move) /p[^r]*{,/**},\n"
 198 "  mount options=(rw,move) /pr[^o]*{,/**},\n"
 199 "  mount options=(rw,move) /pro[^c]*{,/**},\n"
 200 "  mount options=(rw,move) /proc?*{,/**},\n"
 201 "  mount options=(rw,move) /s[^y]*{,/**},\n"
 202 "  mount options=(rw,move) /sy[^s]*{,/**},\n"
 203 "  mount options=(rw,move) /sys?*{,/**},\n"
 204 "\n"
 205 "  # generated by: lxc-generate-aa-rules.py container-rules.base\n"
 206 "  deny /proc/sys/[^kn]*{,/**} wklx,\n"
 207 "  deny /proc/sys/k[^e]*{,/**} wklx,\n"
 208 "  deny /proc/sys/ke[^r]*{,/**} wklx,\n"
 209 "  deny /proc/sys/ker[^n]*{,/**} wklx,\n"
 210 "  deny /proc/sys/kern[^e]*{,/**} wklx,\n"
 211 "  deny /proc/sys/kerne[^l]*{,/**} wklx,\n"
 212 "  deny /proc/sys/kernel/[^smhd]*{,/**} wklx,\n"
 213 "  deny /proc/sys/kernel/d[^o]*{,/**} wklx,\n"
 214 "  deny /proc/sys/kernel/do[^m]*{,/**} wklx,\n"
 215 "  deny /proc/sys/kernel/dom[^a]*{,/**} wklx,\n"
 216 "  deny /proc/sys/kernel/doma[^i]*{,/**} wklx,\n"
 217 "  deny /proc/sys/kernel/domai[^n]*{,/**} wklx,\n"
 218 "  deny /proc/sys/kernel/domain[^n]*{,/**} wklx,\n"
 219 "  deny /proc/sys/kernel/domainn[^a]*{,/**} wklx,\n"
 220 "  deny /proc/sys/kernel/domainna[^m]*{,/**} wklx,\n"
 221 "  deny /proc/sys/kernel/domainnam[^e]*{,/**} wklx,\n"
 222 "  deny /proc/sys/kernel/domainname?*{,/**} wklx,\n"
 223 "  deny /proc/sys/kernel/h[^o]*{,/**} wklx,\n"
 224 "  deny /proc/sys/kernel/ho[^s]*{,/**} wklx,\n"
 225 "  deny /proc/sys/kernel/hos[^t]*{,/**} wklx,\n"
 226 "  deny /proc/sys/kernel/host[^n]*{,/**} wklx,\n"
 227 "  deny /proc/sys/kernel/hostn[^a]*{,/**} wklx,\n"
 228 "  deny /proc/sys/kernel/hostna[^m]*{,/**} wklx,\n"
 229 "  deny /proc/sys/kernel/hostnam[^e]*{,/**} wklx,\n"
 230 "  deny /proc/sys/kernel/hostname?*{,/**} wklx,\n"
 231 "  deny /proc/sys/kernel/m[^s]*{,/**} wklx,\n"
 232 "  deny /proc/sys/kernel/ms[^g]*{,/**} wklx,\n"
 233 "  deny /proc/sys/kernel/msg*/** wklx,\n"
 234 "  deny /proc/sys/kernel/s[^he]*{,/**} wklx,\n"
 235 "  deny /proc/sys/kernel/se[^m]*{,/**} wklx,\n"
 236 "  deny /proc/sys/kernel/sem*/** wklx,\n"
 237 "  deny /proc/sys/kernel/sh[^m]*{,/**} wklx,\n"
 238 "  deny /proc/sys/kernel/shm*/** wklx,\n"
 239 "  deny /proc/sys/kernel?*{,/**} wklx,\n"
 240 "  deny /proc/sys/n[^e]*{,/**} wklx,\n"
 241 "  deny /proc/sys/ne[^t]*{,/**} wklx,\n"
 242 "  deny /proc/sys/net?*{,/**} wklx,\n"
 243 "  deny /sys/[^fdck]*{,/**} wklx,\n"
 244 "  deny /sys/c[^l]*{,/**} wklx,\n"
 245 "  deny /sys/cl[^a]*{,/**} wklx,\n"
 246 "  deny /sys/cla[^s]*{,/**} wklx,\n"
 247 "  deny /sys/clas[^s]*{,/**} wklx,\n"
 248 "  deny /sys/class/[^n]*{,/**} wklx,\n"
 249 "  deny /sys/class/n[^e]*{,/**} wklx,\n"
 250 "  deny /sys/class/ne[^t]*{,/**} wklx,\n"
 251 "  deny /sys/class/net?*{,/**} wklx,\n"
 252 "  deny /sys/class?*{,/**} wklx,\n"
 253 "  deny /sys/d[^e]*{,/**} wklx,\n"
 254 "  deny /sys/de[^v]*{,/**} wklx,\n"
 255 "  deny /sys/dev[^i]*{,/**} wklx,\n"
 256 "  deny /sys/devi[^c]*{,/**} wklx,\n"
 257 "  deny /sys/devic[^e]*{,/**} wklx,\n"
 258 "  deny /sys/device[^s]*{,/**} wklx,\n"
 259 "  deny /sys/devices/[^v]*{,/**} wklx,\n"
 260 "  deny /sys/devices/v[^i]*{,/**} wklx,\n"
 261 "  deny /sys/devices/vi[^r]*{,/**} wklx,\n"
 262 "  deny /sys/devices/vir[^t]*{,/**} wklx,\n"
 263 "  deny /sys/devices/virt[^u]*{,/**} wklx,\n"
 264 "  deny /sys/devices/virtu[^a]*{,/**} wklx,\n"
 265 "  deny /sys/devices/virtua[^l]*{,/**} wklx,\n"
 266 "  deny /sys/devices/virtual/[^n]*{,/**} wklx,\n"
 267 "  deny /sys/devices/virtual/n[^e]*{,/**} wklx,\n"
 268 "  deny /sys/devices/virtual/ne[^t]*{,/**} wklx,\n"
 269 "  deny /sys/devices/virtual/net?*{,/**} wklx,\n"
 270 "  deny /sys/devices/virtual?*{,/**} wklx,\n"
 271 "  deny /sys/devices?*{,/**} wklx,\n"
 272 "  deny /sys/f[^s]*{,/**} wklx,\n"
 273 "  deny /sys/fs/[^c]*{,/**} wklx,\n"
 274 "  deny /sys/fs/c[^g]*{,/**} wklx,\n"
 275 "  deny /sys/fs/cg[^r]*{,/**} wklx,\n"
 276 "  deny /sys/fs/cgr[^o]*{,/**} wklx,\n"
 277 "  deny /sys/fs/cgro[^u]*{,/**} wklx,\n"
 278 "  deny /sys/fs/cgrou[^p]*{,/**} wklx,\n"
 279 "  deny /sys/fs/cgroup?*{,/**} wklx,\n"
 280 "  deny /sys/fs?*{,/**} wklx,\n"
 281 ;
 282
 283 static const char AA_PROFILE_UNIX_SOCKETS[] =
 284 "\n"
 285 "  ### Feature: unix\n"
 286 "  # Allow receive via unix sockets from anywhere\n"
 287 "  unix (receive),\n"
 288 "\n"
 289 "  # Allow all unix sockets in the container\n"
 290 "  unix peer=(label=@{profile_name}),\n"
 291 ;
 292
 293 static const char AA_PROFILE_CGROUP_NAMESPACES[] =
 294 "\n"
 295 "  ### Feature: cgroup namespace\n"
 296 "  mount fstype=cgroup -> /sys/fs/cgroup/**,\n"
 297 "  mount fstype=cgroup2 -> /sys/fs/cgroup/**,\n"
 298 ;
 299
 300 /* '_BASE' because we still need to append generated change_profile rules */
 301 static const char AA_PROFILE_STACKING_BASE[] =
 302 "\n"
 303 "  ### Feature: apparmor stacking\n"
 304 "  ### Configuration: apparmor profile loading (in namespace)\n"
 305 "  deny /sys/k[^e]*{,/**} wklx,\n"
 306 "  deny /sys/ke[^r]*{,/**} wklx,\n"
 307 "  deny /sys/ker[^n]*{,/**} wklx,\n"
 308 "  deny /sys/kern[^e]*{,/**} wklx,\n"
 309 "  deny /sys/kerne[^l]*{,/**} wklx,\n"
 310 "  deny /sys/kernel/[^s]*{,/**} wklx,\n"
 311 "  deny /sys/kernel/s[^e]*{,/**} wklx,\n"
 312 "  deny /sys/kernel/se[^c]*{,/**} wklx,\n"
 313 "  deny /sys/kernel/sec[^u]*{,/**} wklx,\n"
 314 "  deny /sys/kernel/secu[^r]*{,/**} wklx,\n"
 315 "  deny /sys/kernel/secur[^i]*{,/**} wklx,\n"
 316 "  deny /sys/kernel/securi[^t]*{,/**} wklx,\n"
 317 "  deny /sys/kernel/securit[^y]*{,/**} wklx,\n"
 318 "  deny /sys/kernel/security/[^a]*{,/**} wklx,\n"
 319 "  deny /sys/kernel/security/a[^p]*{,/**} wklx,\n"
 320 "  deny /sys/kernel/security/ap[^p]*{,/**} wklx,\n"
 321 "  deny /sys/kernel/security/app[^a]*{,/**} wklx,\n"
 322 "  deny /sys/kernel/security/appa[^r]*{,/**} wklx,\n"
 323 "  deny /sys/kernel/security/appar[^m]*{,/**} wklx,\n"
 324 "  deny /sys/kernel/security/apparm[^o]*{,/**} wklx,\n"
 325 "  deny /sys/kernel/security/apparmo[^r]*{,/**} wklx,\n"
 326 "  deny /sys/kernel/security/apparmor?*{,/**} wklx,\n"
 327 "  deny /sys/kernel/security?*{,/**} wklx,\n"
 328 "  deny /sys/kernel?*{,/**} wklx,\n"
 329 ;
 330
 331 static const char AA_PROFILE_NO_STACKING[] =
 332 "\n"
 333 "  ### Feature: apparmor stacking (not present)\n"
 334 "  deny /sys/k*{,/**} rwklx,\n"
 335 ;
 336
 337 /* '_BASE' because we need to append change_profile for stacking */
 338 static const char AA_PROFILE_NESTING_BASE[] =
 339 "\n"
 340 "  ### Configuration: nesting\n"
 341 "  pivot_root,\n"
 342 "  ptrace,\n"
 343 "  signal,\n"
 344 "\n"
 345    /* NOTE: See conf.c's "nesting_helpers" for details. */
 346 "  deny /dev/.lxc/proc/** rw,\n"
 347 "  deny /dev/.lxc/sys/** rw,\n"
 348 "\n"
 349 "  mount fstype=proc -> /usr/lib/*/lxc/**,\n"
 350 "  mount fstype=sysfs -> /usr/lib/*/lxc/**,\n"
 351 "  mount options=(rw,bind),\n"
 352 "  mount options=(rw,rbind),\n"
 353 "  mount options=(rw,make-rshared),\n"
 354 "\n"
 355    /* FIXME: What's the state here on apparmor's side? */
 356 "  # there doesn't seem to be a way to ask for:\n"
 357 "  # mount options=(ro,nosuid,nodev,noexec,remount,bind),\n"
 358 "  # as we always get mount to $cdir/proc/sys with those flags denied\n"
 359 "  # So allow all mounts until that is straightened out:\n"
 360 "  mount,\n"
 361 ;
 362
 363 static const char AA_PROFILE_UNPRIVILEGED[] =
 364 "\n"
 365 "  ### Configuration: unprivileged container\n"
 366 "  pivot_root,\n"
 367 "\n"
 368 "  # Allow modifying mount propagation\n"
 369 "  mount options=(rw,make-slave) -> **,\n"
 370 "  mount options=(rw,make-rslave) -> **,\n"
 371 "  mount options=(rw,make-shared) -> **,\n"
 372 "  mount options=(rw,make-rshared) -> **,\n"
 373 "  mount options=(rw,make-private) -> **,\n"
 374 "  mount options=(rw,make-rprivate) -> **,\n"
 375 "  mount options=(rw,make-unbindable) -> **,\n"
 376 "  mount options=(rw,make-runbindable) -> **,\n"
 377 "\n"
 378 "  # Allow all bind-mounts\n"
 379 "  mount options=(rw,bind),\n"
 380 "  mount options=(rw,rbind),\n"
 381 "\n"
 382 "  # Allow remounting things read-only\n"
 383 "  mount options=(ro,remount),\n"
 384 ;
 385
 386 static bool check_mount_feature_enabled(void)
 387 {
 388         return mount_features_enabled == 1;
 389 }
 390
 391 static void load_mount_features_enabled(void)
 392 {
 393         struct stat statbuf;
 394         int ret;
 395
 396         ret = stat(AA_MOUNT_RESTR, &statbuf);
 397         if (ret == 0)
 398                 mount_features_enabled = 1;
 399 }
 400
 401 /* aa_getcon is not working right now.  Use our hand-rolled version below */
 402 static int apparmor_enabled(void)
 403 {
 404         FILE *fin;
 405         char e;
 406         int ret;
 407
 408         fin = fopen_cloexec(AA_ENABLED_FILE, "r");
 409         if (!fin)
 410                 return 0;
 411         ret = fscanf(fin, "%c", &e);
 412         fclose(fin);
 413         if (ret == 1 && e == 'Y') {
 414                 load_mount_features_enabled();
 415                 return 1;
 416         }
 417
 418         return 0;
 419 }
 420
 421 static char *apparmor_process_label_get(pid_t pid)
 422 {
 423         char path[100], *space;
 424         int ret;
 425         char *buf = NULL, *newbuf;
 426         int sz = 0;
 427         FILE *f;
 428
 429         ret = snprintf(path, 100, "/proc/%d/attr/current", pid);
 430         if (ret < 0 || ret >= 100) {
 431                 ERROR("path name too long");
 432                 return NULL;
 433         }
 434 again:
 435         f = fopen_cloexec(path, "r");
 436         if (!f) {
 437                 SYSERROR("opening %s", path);
 438                 free(buf);
 439                 return NULL;
 440         }
 441         sz += 1024;
 442         newbuf = realloc(buf, sz);
 443         if (!newbuf) {
 444                 free(buf);
 445                 ERROR("out of memory");
 446                 fclose(f);
 447                 return NULL;
 448         }
 449         buf = newbuf;
 450         memset(buf, 0, sz);
 451         ret = fread(buf, 1, sz - 1, f);
 452         fclose(f);
 453         if (ret < 0) {
 454                 ERROR("reading %s", path);
 455                 free(buf);
 456                 return NULL;
 457         }
 458         if (ret >= sz)
 459                 goto again;
 460         space = strchr(buf, '\n');
 461         if (space)
 462                 *space = '\0';
 463         space = strchr(buf, ' ');
 464         if (space)
 465                 *space = '\0';
 466         return buf;
 467 }
 468
 469 /*
 470  * Probably makes sense to reorganize these to only read
 471  * the label once
 472  */
 473 static bool apparmor_am_unconfined(void)
 474 {
 475         char *p = apparmor_process_label_get(lxc_raw_getpid());
 476         bool ret = false;
 477         if (!p || strcmp(p, "unconfined") == 0)
 478                 ret = true;
 479         free(p);
 480         return ret;
 481 }
 482
 483 static bool aa_needs_transition(char *curlabel)
 484 {
 485         if (!curlabel)
 486                 return false;
 487         if (strcmp(curlabel, "unconfined") == 0)
 488                 return false;
 489         if (strcmp(curlabel, "/usr/bin/lxc-start") == 0)
 490                 return false;
 491         return true;
 492 }
 493
 494 static inline void uint64hex(char *buf, uint64_t num)
 495 {
 496         size_t i;
 497
 498         buf[16] = 0;
 499         for (i = 16; i--;) {
 500                 char c = (char)(num & 0xf);
 501                 buf[i] = c + (c < 0xa ? '0' : 'a' - 0xa);
 502                 num >>= 4;
 503         }
 504 }
 505
 506 static inline char *shorten_apparmor_name(char *name)
 507 {
 508         size_t len = strlen(name);
 509         if (len + 7 > 253) {
 510                 uint64_t hash;
 511                 hash = fnv_64a_buf(name, len, FNV1A_64_INIT);
 512                 name = must_realloc(name, 16 + 1);
 513                 uint64hex(name, hash);
 514         }
 515
 516         return name;
 517 }
 518
 519 /* Replace slashes with hyphens */
 520 static inline void sanitize_path(char *path)
 521 {
 522         size_t i;
 523
 524         for (i = 0; path[i]; i++)
 525                 if (path[i] == '/')
 526                         path[i] = '-';
 527 }
 528
 529 static inline char *apparmor_dir(const char *ctname, const char *lxcpath)
 530 {
 531         return must_make_path(lxcpath, ctname, "apparmor", NULL);
 532 }
 533
 534
 535 static inline char *apparmor_profile_full(const char *ctname, const char *lxcpath)
 536 {
 537         return shorten_apparmor_name(must_concat("lxc-", ctname, "_<", lxcpath, ">", NULL));
 538 }
 539
 540 /* Like apparmor_profile_full() but with slashes replaced by hyphens */
 541 static inline char *apparmor_namespace(const char *ctname, const char *lxcpath)
 542 {
 543         char *full;
 544
 545         full = apparmor_profile_full(ctname, lxcpath);
 546         sanitize_path(full);
 547
 548         return full;
 549 }
 550
 551 /* FIXME: This is currently run only in the context of a constructor (via the
 552  * initial lsm_init() called due to its __attribute__((constructor)), so we
 553  * do not have ERROR/... macros available, so there are some fprintf(stderr)s
 554  * in there.
 555  */
 556 static bool check_apparmor_parser_version()
 557 {
 558         struct lxc_popen_FILE *parserpipe;
 559         int rc;
 560         int major = 0, minor = 0, micro = 0;
 561
 562         parserpipe = lxc_popen("apparmor_parser --version");
 563         if (!parserpipe) {
 564                 fprintf(stderr, "Failed to run check for apparmor_parser\n");
 565                 return false;
 566         }
 567
 568         rc = fscanf(parserpipe->f, "AppArmor parser version %d.%d.%d", &major, &minor, &micro);
 569         if (rc < 1) {
 570                 lxc_pclose(parserpipe);
 571                 /* We stay silent for now as this most likely means the shell
 572                  * lxc_popen executed failed to find the apparmor_parser binary.
 573                  * See the FIXME comment above for details.
 574                  */
 575                 return false;
 576         }
 577
 578         rc = lxc_pclose(parserpipe);
 579         if (rc < 0) {
 580                 fprintf(stderr, "Error waiting for child process\n");
 581                 return false;
 582         }
 583         if (rc != 0) {
 584                 fprintf(stderr, "'apparmor_parser --version' executed with an error status\n");
 585                 return false;
 586         }
 587
 588         aa_supports_unix = (major > 2) ||
 589                            (major == 2 && minor > 10) ||
 590                            (major == 2 && minor == 10 && micro >= 95);
 591
 592         return true;
 593 }
 594
 595 static bool file_is_yes(const char *path)
 596 {
 597         ssize_t rd;
 598         int fd;
 599         char buf[8]; /* we actually just expect "yes" or "no" */
 600
 601         fd = open(path, O_RDONLY | O_CLOEXEC);
 602         if (fd < 0)
 603                 return false;
 604
 605         rd = lxc_read_nointr(fd, buf, sizeof(buf));
 606         close(fd);
 607
 608         return rd >= 4 && strncmp(buf, "yes\n", 4) == 0;
 609 }
 610
 611 static bool apparmor_can_stack()
 612 {
 613         int major, minor, scanned;
 614         FILE *f;
 615
 616         if (!file_is_yes("/sys/kernel/security/apparmor/features/domain/stack"))
 617                 return false;
 618
 619         f = fopen_cloexec("/sys/kernel/security/apparmor/features/domain/version", "r");
 620         if (!f)
 621                 return false;
 622
 623         scanned = fscanf(f, "%d.%d", &major, &minor);
 624         fclose(f);
 625         if (scanned != 2)
 626                 return false;
 627
 628         return major > 1 || (major == 1 && minor >= 2);
 629 }
 630
 631 static void must_append_sized_full(char **buf, size_t *bufsz, const char *data,
 632                                    size_t size, bool append_newline)
 633 {
 634         size_t newsize = *bufsz + size;
 635
 636         if (append_newline)
 637                 ++newsize;
 638
 639         *buf = must_realloc(*buf, newsize);
 640         memcpy(*buf + *bufsz, data, size);
 641
 642         if (append_newline)
 643                 (*buf)[newsize - 1] = '\n';
 644
 645         *bufsz = newsize;
 646 }
 647
 648 static void must_append_sized(char **buf, size_t *bufsz, const char *data, size_t size)
 649 {
 650         return must_append_sized_full(buf, bufsz, data, size, false);
 651 }
 652
 653 static bool is_privileged(struct lxc_conf *conf)
 654 {
 655         return lxc_list_empty(&conf->id_map);
 656 }
 657
 658 static char *get_apparmor_profile_content(struct lxc_conf *conf, const char *lxcpath)
 659 {
 660         char *profile, *profile_name_full;
 661         size_t size;
 662         struct lxc_list *it;
 663
 664         profile_name_full = apparmor_profile_full(conf->name, lxcpath);
 665
 666         profile = must_concat(
 667 "#include <tunables/global>\n"
 668 "profile \"", profile_name_full, "\" flags=(attach_disconnected,mediate_deleted) {\n",
 669                               NULL);
 670         size = strlen(profile);
 671
 672         must_append_sized(&profile, &size, AA_PROFILE_BASE,
 673                           STRARRAYLEN(AA_PROFILE_BASE));
 674
 675         if (aa_supports_unix)
 676                 must_append_sized(&profile, &size, AA_PROFILE_UNIX_SOCKETS,
 677                                   STRARRAYLEN(AA_PROFILE_UNIX_SOCKETS));
 678
 679         if (file_exists("/proc/self/ns/cgroup"))
 680                 must_append_sized(&profile, &size, AA_PROFILE_CGROUP_NAMESPACES,
 681                                   STRARRAYLEN(AA_PROFILE_CGROUP_NAMESPACES));
 682
 683         if (aa_can_stack && !aa_is_stacked) {
 684                 char *namespace, *temp;
 685
 686                 must_append_sized(&profile, &size, AA_PROFILE_STACKING_BASE,
 687                                   STRARRAYLEN(AA_PROFILE_STACKING_BASE));
 688
 689                 namespace = apparmor_namespace(conf->name, lxcpath);
 690                 temp = must_concat("  change_profile -> \":", namespace, ":*\",\n"
 691                                    "  change_profile -> \":", namespace, "://*\",\n",
 692                                    NULL);
 693                 free(namespace);
 694
 695                 must_append_sized(&profile, &size, temp, strlen(temp));
 696                 free(temp);
 697         } else {
 698                 must_append_sized(&profile, &size, AA_PROFILE_NO_STACKING,
 699                                   STRARRAYLEN(AA_PROFILE_NO_STACKING));
 700         }
 701
 702         if (conf->lsm_aa_allow_nesting) {
 703                 must_append_sized(&profile, &size, AA_PROFILE_NESTING_BASE,
 704                                   STRARRAYLEN(AA_PROFILE_NESTING_BASE));
 705
 706                 if (!aa_can_stack || aa_is_stacked) {
 707                         char *temp;
 708
 709                         temp = must_concat("  change_profile -> \"",
 710                                            profile_name_full, "\",\n", NULL);
 711                         must_append_sized(&profile, &size, temp, strlen(temp));
 712                         free(temp);
 713                 }
 714         }
 715
 716         if (!is_privileged(conf) || am_host_unpriv())
 717                 must_append_sized(&profile, &size, AA_PROFILE_UNPRIVILEGED,
 718                                   STRARRAYLEN(AA_PROFILE_UNPRIVILEGED));
 719
 720         lxc_list_for_each(it, &conf->lsm_aa_raw) {
 721                 const char *line = it->elem;
 722
 723                 must_append_sized_full(&profile, &size, line, strlen(line), true);
 724         }
 725
 726         /* include terminating \0 byte */
 727         must_append_sized(&profile, &size, "}\n", 3);
 728
 729         free(profile_name_full);
 730
 731         return profile;
 732 }
 733
 734 /*
 735  * apparmor_parser creates a cache file using the parsed file's name as a name.
 736  * This means there may be multiple containers with the same name but different
 737  * lxcpaths. Therefore we need a sanitized version of the complete profile name
 738  * as profile file-name.
 739  * We already get this exactly from apparmor_namespace().
 740  */
 741 static char *make_apparmor_profile_path(const char *ctname, const char *lxcpath)
 742 {
 743         char *ret, *filename;
 744
 745         filename = apparmor_namespace(ctname, lxcpath);
 746         ret = must_make_path(lxcpath, ctname, "apparmor", filename, NULL);
 747         free(filename);
 748
 749         return ret;
 750 }
 751
 752 static char *make_apparmor_namespace_path(const char *ctname, const char *lxcpath)
 753 {
 754         char *ret, *namespace;
 755
 756         namespace = apparmor_namespace(ctname, lxcpath);
 757         ret = must_make_path("/sys/kernel/security/apparmor/policy/namespaces", namespace, NULL);
 758         free(namespace);
 759
 760         return ret;
 761 }
 762
 763 static bool make_apparmor_namespace(struct lxc_conf *conf, const char *lxcpath)
 764 {
 765         char *path;
 766
 767         if (!aa_can_stack || aa_is_stacked)
 768                 return true;
 769
 770         path = make_apparmor_namespace_path(conf->name, lxcpath);
 771         errno = 0;
 772         if (mkdir(path, 0755) < 0 && errno != EEXIST) {
 773                 SYSERROR("Error creating AppArmor namespace: %s", path);
 774                 free(path);
 775                 return false;
 776         }
 777         free(path);
 778
 779         return true;
 780 }
 781
 782 static void remove_apparmor_namespace(struct lxc_conf *conf, const char *lxcpath)
 783 {
 784         char *path;
 785
 786         path = make_apparmor_namespace_path(conf->name, lxcpath);
 787         if (rmdir(path) != 0)
 788                 SYSERROR("Error removing AppArmor namespace");
 789         free(path);
 790 }
 791
 792 struct apparmor_parser_args {
 793         char cmd;
 794         char *file;
 795 };
 796
 797 static int apparmor_parser_exec(void *data)
 798 {
 799         struct apparmor_parser_args *args = data;
 800         char cmdbuf[] = { '-', args->cmd, 'W', 'L', 0 };
 801
 802         execlp("apparmor_parser", "apparmor_parser", cmdbuf, APPARMOR_CACHE_DIR, args->file, NULL);
 803
 804         return -1;
 805 }
 806
 807 static int run_apparmor_parser(char command,
 808                                struct lxc_conf *conf,
 809                                const char *lxcpath)
 810 {
 811         char output[MAXPATHLEN];
 812         int ret;
 813         struct apparmor_parser_args args = {
 814                 .cmd = command,
 815                 .file = make_apparmor_profile_path(conf->name, lxcpath),
 816         };
 817
 818         ret = run_command(output, sizeof(output), apparmor_parser_exec, (void*)&args);
 819         if (ret < 0) {
 820                 ERROR("Failed to run apparmor_parser on \"%s\": %s", args.file, output);
 821                 ret = -1;
 822         }
 823
 824
 825         free(args.file);
 826         return ret;
 827 }
 828
 829 static void remove_apparmor_profile(struct lxc_conf *conf, const char *lxcpath)
 830 {
 831         char *path;
 832
 833         /* It's ok if these deletes fail: if the container was never started,
 834          * we'll have never written a profile or cached it.
 835          */
 836
 837         path = make_apparmor_profile_path(conf->name, lxcpath);
 838         (void)unlink(path);
 839         free(path);
 840
 841         /* Also remove the apparmor/ subdirectory */
 842         path = apparmor_dir(conf->name, lxcpath);
 843         (void)rmdir(path);
 844         free(path);
 845 }
 846
 847 static int load_apparmor_profile(struct lxc_conf *conf, const char *lxcpath)
 848 {
 849         struct stat profile_sb;
 850         size_t content_len;
 851         int ret = -1;
 852         size_t old_len = 0;
 853         char *profile_path = NULL, *old_content = NULL, *new_content = NULL;
 854         int profile_fd = -1;
 855
 856         if (!make_apparmor_namespace(conf, lxcpath))
 857                 return -1;
 858
 859         /* In order to avoid forcing a profile parse (potentially slow) on
 860          * every container start, let's use apparmor's binary policy cache,
 861          * which checks mtime of the files to figure out if the policy needs to
 862          * be regenerated.
 863          *
 864          * Since it uses mtimes, we shouldn't just always write out our local
 865          * apparmor template; instead we should check to see whether the
 866          * template is the same as ours. If it isn't we should write our
 867          * version out so that the new changes are reflected and we definitely
 868          * force a recompile.
 869          */
 870
 871         profile_path = make_apparmor_profile_path(conf->name, lxcpath);
 872         profile_fd = open(profile_path, O_RDONLY | O_CLOEXEC);
 873         if (profile_fd >= 0) {
 874                 if (fstat(profile_fd, &profile_sb) < 0) {
 875                         SYSERROR("Error accessing old profile from %s",
 876                                  profile_path);
 877                         goto out;
 878                 }
 879                 old_len = profile_sb.st_size;
 880                 old_content = lxc_strmmap(NULL, old_len, PROT_READ,
 881                                           MAP_PRIVATE, profile_fd, 0);
 882                 if (!old_content) {
 883                         SYSERROR("Failed to mmap old profile from %s",
 884                                  profile_path);
 885                         goto out;
 886                 }
 887         } else if (errno != ENOENT) {
 888                 SYSERROR("Error reading old profile from %s", profile_path);
 889                 goto out;
 890         }
 891
 892         new_content = get_apparmor_profile_content(conf, lxcpath);
 893         if (!new_content)
 894                 goto out;
 895
 896         content_len = strlen(new_content);
 897
 898         if (!old_content || old_len != content_len || memcmp(old_content, new_content, content_len) != 0) {
 899                 char *path;
 900
 901                 ret = mkdir_p(APPARMOR_CACHE_DIR, 0755);
 902                 if (ret < 0) {
 903                         SYSERROR("Error creating AppArmor profile cache directory " APPARMOR_CACHE_DIR);
 904                         goto out;
 905                 }
 906
 907                 path = apparmor_dir(conf->name, lxcpath);
 908                 ret = mkdir_p(path, 0755);
 909                 if (ret < 0) {
 910                         SYSERROR("Error creating AppArmor profile directory: %s", path);
 911                         free(path);
 912                         goto out;
 913                 }
 914                 free(path);
 915
 916                 ret = lxc_write_to_file(profile_path, new_content, content_len, false, 0600);
 917                 if (ret < 0) {
 918                         SYSERROR("Error writing profile to %s", profile_path);
 919                         goto out;
 920                 }
 921         }
 922
 923         ret = run_apparmor_parser(AA_CMD_LOAD, conf, lxcpath);
 924         if (ret != 0)
 925                 goto out_remove_profile;
 926
 927         conf->lsm_aa_profile_created = true;
 928
 929         goto out_ok;
 930
 931 out_remove_profile:
 932         remove_apparmor_profile(conf, lxcpath);
 933 out:
 934         remove_apparmor_namespace(conf, lxcpath);
 935 out_ok:
 936         if (profile_fd >= 0) {
 937                 if (old_content)
 938                         lxc_strmunmap(old_content, old_len);
 939                 close(profile_fd);
 940         }
 941         free(profile_path);
 942         free(new_content);
 943         return ret;
 944 }
 945
 946 /*
 947  * Ensure that the container's policy namespace is unloaded to free kernel
 948  * memory. This does not delete the policy from disk or cache.
 949  */
 950 static void apparmor_cleanup(struct lxc_conf *conf, const char *lxcpath)
 951 {
 952         if (!aa_admin)
 953                 return;
 954
 955         if (!conf->lsm_aa_profile_created)
 956                 return;
 957
 958         remove_apparmor_namespace(conf, lxcpath);
 959         (void)run_apparmor_parser(AA_CMD_UNLOAD, conf, lxcpath);
 960
 961         remove_apparmor_profile(conf, lxcpath);
 962 }
 963
 964 static int apparmor_prepare(struct lxc_conf *conf, const char *lxcpath)
 965 {
 966         int ret = -1;
 967         const char *label;
 968         char *curlabel = NULL, *genlabel = NULL;
 969
 970         if (!aa_enabled) {
 971                 ERROR("AppArmor not enabled");
 972                 return -1;
 973         }
 974
 975         label = conf->lsm_aa_profile;
 976
 977         /* user may request that we just ignore apparmor */
 978         if (label && strcmp(label, AA_UNCHANGED) == 0) {
 979                 INFO("AppArmor profile unchanged per user request");
 980                 conf->lsm_aa_profile_computed = must_copy_string(label);
 981                 return 0;
 982         }
 983
 984         if (label && strcmp(label, AA_GENERATED) == 0) {
 985                 if (!aa_parser_available) {
 986                         ERROR("Cannot use generated profile: apparmor_parser not available");
 987                         goto out;
 988                 }
 989
 990                 /* auto-generate profile based on available/requested security features */
 991                 if (load_apparmor_profile(conf, lxcpath) != 0) {
 992                         ERROR("Failed to load generated AppArmor profile");
 993                         goto out;
 994                 }
 995
 996                 genlabel = apparmor_profile_full(conf->name, lxcpath);
 997                 if (!genlabel) {
 998                         ERROR("Failed to build AppArmor profile name");
 999                         goto out;
1000                 }
1001
1002                 if (aa_can_stack && !aa_is_stacked) {
1003                         char *namespace = apparmor_namespace(conf->name, lxcpath);
1004                         size_t llen = strlen(genlabel);
1005                         must_append_sized(&genlabel, &llen, "//&:", STRARRAYLEN("//&:"));
1006                         must_append_sized(&genlabel, &llen, namespace, strlen(namespace));
1007                         must_append_sized(&genlabel, &llen, ":", STRARRAYLEN(":") + 1); /* with the nul byte */
1008                         free(namespace);
1009                 }
1010
1011                 label = genlabel;
1012         }
1013
1014         curlabel = apparmor_process_label_get(lxc_raw_getpid());
1015
1016         if (!aa_can_stack && aa_needs_transition(curlabel)) {
1017                 /* we're already confined, and stacking isn't supported */
1018
1019                 if (!label || strcmp(curlabel, label) == 0) {
1020                         /* no change requested */
1021                         ret = 0;
1022                         goto out;
1023                 }
1024
1025                 ERROR("Already AppArmor confined, but new label requested.");
1026                 goto out;
1027         }
1028
1029         if (!label) {
1030                 if (cgns_supported())
1031                         label = AA_DEF_PROFILE_CGNS;
1032                 else
1033                         label = AA_DEF_PROFILE;
1034         }
1035
1036         if (!check_mount_feature_enabled() && strcmp(label, "unconfined") != 0) {
1037                 WARN("Incomplete AppArmor support in your kernel");
1038                 if (!conf->lsm_aa_allow_incomplete) {
1039                         ERROR("If you really want to start this container, set");
1040                         ERROR("lxc.apparmor.allow_incomplete = 1");
1041                         ERROR("in your container configuration file");
1042                         goto out;
1043                 }
1044         }
1045
1046         conf->lsm_aa_profile_computed = must_copy_string(label);
1047         ret = 0;
1048
1049 out:
1050         if (genlabel) {
1051                 free(genlabel);
1052                 if (ret != 0)
1053                         apparmor_cleanup(conf, lxcpath);
1054         }
1055         free(curlabel);
1056         return ret;
1057 }
1058
1059 /*
1060  * apparmor_process_label_set: Set AppArmor process profile
1061  *
1062  * @label   : the profile to set
1063  * @conf    : the container configuration to use if @label is NULL
1064  * @default : use the default profile if @label is NULL
1065  * @on_exec : this is ignored.  Apparmor profile will be changed immediately
1066  *
1067  * Returns 0 on success, < 0 on failure
1068  *
1069  * Notes: This relies on /proc being available.
1070  */
1071 static int apparmor_process_label_set(const char *inlabel, struct lxc_conf *conf,
1072                                       bool on_exec)
1073 {
1074         int label_fd, ret;
1075         pid_t tid;
1076         const char *label;
1077
1078         if (!aa_enabled) {
1079                 ERROR("AppArmor not enabled");
1080                 return -1;
1081         }
1082
1083         label = inlabel ? inlabel : conf->lsm_aa_profile_computed;
1084         if (!label) {
1085                 ERROR("LSM wasn't prepared");
1086                 return -1;
1087         }
1088
1089         /* user may request that we just ignore apparmor */
1090         if (strcmp(label, AA_UNCHANGED) == 0) {
1091                 INFO("AppArmor profile unchanged per user request");
1092                 return 0;
1093         }
1094
1095         if (strcmp(label, "unconfined") == 0 && apparmor_am_unconfined()) {
1096                 INFO("AppArmor profile unchanged");
1097                 return 0;
1098         }
1099         tid = lxc_raw_gettid();
1100         label_fd = lsm_process_label_fd_get(tid, on_exec);
1101         if (label_fd < 0) {
1102                 SYSERROR("Failed to change AppArmor profile to %s", label);
1103                 return -1;
1104         }
1105
1106         ret = lsm_process_label_set_at(label_fd, label, on_exec);
1107         close(label_fd);
1108         if (ret < 0) {
1109                 ERROR("Failed to change AppArmor profile to %s", label);
1110                 return -1;
1111         }
1112
1113         INFO("Changed AppArmor profile to %s", label);
1114         return 0;
1115 }
1116
1117 static struct lsm_drv apparmor_drv = {
1118         .name = "AppArmor",
1119         .enabled           = apparmor_enabled,
1120         .process_label_get = apparmor_process_label_get,
1121         .process_label_set = apparmor_process_label_set,
1122         .prepare           = apparmor_prepare,
1123         .cleanup           = apparmor_cleanup,
1124 };
1125
1126 struct lsm_drv *lsm_apparmor_drv_init(void)
1127 {
1128         bool have_mac_admin = false;
1129
1130         if (!apparmor_enabled())
1131                 return NULL;
1132
1133         /* We only support generated profiles when apparmor_parser is usable */
1134         if (!check_apparmor_parser_version())
1135                 goto out;
1136
1137         aa_parser_available = true;
1138
1139         aa_can_stack = apparmor_can_stack();
1140         if (aa_can_stack)
1141                 aa_is_stacked = file_is_yes("/sys/kernel/security/apparmor/.ns_stacked");
1142
1143         #if HAVE_LIBCAP
1144         have_mac_admin = lxc_proc_cap_is_set(CAP_SETGID, CAP_EFFECTIVE);
1145         #endif
1146
1147         if (!have_mac_admin)
1148                 WARN("Per-container AppArmor profiles are disabled because the mac_admin capability is missing");
1149         else if (am_host_unpriv() && !aa_is_stacked)
1150                 WARN("Per-container AppArmor profiles are disabled because LXC is running in an unprivileged container without stacking");
1151         else
1152                 aa_admin = true;
1153
1154 out:
1155         aa_enabled = 1;
1156         return &apparmor_drv;
1157 }