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 "raw_syscalls.h"
  41 #include "utils.h"
  42
  43 lxc_log_define(apparmor, lsm);
  44
  45 /* set by lsm_apparmor_drv_init if true */
  46 static int aa_enabled = 0;
  47 static bool aa_parser_available = false;
  48 static bool aa_supports_unix = false;
  49 static bool aa_can_stack = false;
  50 static bool aa_is_stacked = false;
  51 static bool aa_admin = false;
  52
  53 static int mount_features_enabled = 0;
  54
  55 #define AA_DEF_PROFILE "lxc-container-default"
  56 #define AA_DEF_PROFILE_CGNS "lxc-container-default-cgns"
  57 #define AA_MOUNT_RESTR "/sys/kernel/security/apparmor/features/mount/mask"
  58 #define AA_ENABLED_FILE "/sys/module/apparmor/parameters/enabled"
  59 #define AA_UNCHANGED "unchanged"
  60 #define AA_GENERATED "generated"
  61
  62 #define AA_CMD_LOAD   'r'
  63 #define AA_CMD_UNLOAD 'R'
  64 #define AA_CMD_PARSE  'Q'
  65
  66 static const char AA_PROFILE_BASE[] =
  67 "  ### Base profile\n"
  68 "  capability,\n"
  69 "  dbus,\n"
  70 "  file,\n"
  71 "  network,\n"
  72 "  umount,\n"
  73 "\n"
  74 "  # Allow us to receive signals from anywhere.\n"
  75 "  signal (receive),\n"
  76 "\n"
  77 "  # Allow us to send signals to ourselves\n"
  78 "  signal peer=@{profile_name},\n"
  79 "\n"
  80 "  # Allow other processes to read our /proc entries, futexes, perf tracing and\n"
  81 "  # kcmp for now (they will need 'read' in the first place). Administrators can\n"
  82 "  # override with:\n"
  83 "  #   deny ptrace (readby) ...\n"
  84 "  ptrace (readby),\n"
  85 "\n"
  86 "  # Allow other processes to trace us by default (they will need 'trace' in\n"
  87 "  # the first place). Administrators can override with:\n"
  88 "  #   deny ptrace (tracedby) ...\n"
  89 "  ptrace (tracedby),\n"
  90 "\n"
  91 "  # Allow us to ptrace ourselves\n"
  92 "  ptrace peer=@{profile_name},\n"
  93 "\n"
  94 "  # ignore DENIED message on / remount\n"
  95 "  deny mount options=(ro, remount) -> /,\n"
  96 "  deny mount options=(ro, remount, silent) -> /,\n"
  97 "\n"
  98 "  # allow tmpfs mounts everywhere\n"
  99 "  mount fstype=tmpfs,\n"
 100 "\n"
 101 "  # allow hugetlbfs mounts everywhere\n"
 102 "  mount fstype=hugetlbfs,\n"
 103 "\n"
 104 "  # allow mqueue mounts everywhere\n"
 105 "  mount fstype=mqueue,\n"
 106 "\n"
 107 "  # allow fuse mounts everywhere\n"
 108 "  mount fstype=fuse,\n"
 109 "  mount fstype=fuse.*,\n"
 110 "\n"
 111 "  # deny access under /proc/bus to avoid e.g. messing with pci devices directly\n"
 112 "  deny @{PROC}/bus/** wklx,\n"
 113 "\n"
 114 "  # deny writes in /proc/sys/fs but allow binfmt_misc to be mounted\n"
 115 "  mount fstype=binfmt_misc -> /proc/sys/fs/binfmt_misc/,\n"
 116 "  deny @{PROC}/sys/fs/** wklx,\n"
 117 "\n"
 118 "  # allow efivars to be mounted, writing to it will be blocked though\n"
 119 "  mount fstype=efivarfs -> /sys/firmware/efi/efivars/,\n"
 120 "\n"
 121 "  # block some other dangerous paths\n"
 122 "  deny @{PROC}/kcore rwklx,\n"
 123 "  deny @{PROC}/sysrq-trigger rwklx,\n"
 124 "\n"
 125 "  # deny writes in /sys except for /sys/fs/cgroup, also allow\n"
 126 "  # fusectl, securityfs and debugfs to be mounted there (read-only)\n"
 127 "  mount fstype=fusectl -> /sys/fs/fuse/connections/,\n"
 128 "  mount fstype=securityfs -> /sys/kernel/security/,\n"
 129 "  mount fstype=debugfs -> /sys/kernel/debug/,\n"
 130 "  deny mount fstype=debugfs -> /var/lib/ureadahead/debugfs/,\n"
 131 "  mount fstype=proc -> /proc/,\n"
 132 "  mount fstype=sysfs -> /sys/,\n"
 133 "  mount options=(rw, nosuid, nodev, noexec, remount) -> /sys/,\n"
 134 "  deny /sys/firmware/efi/efivars/** rwklx,\n"
 135 "  # note, /sys/kernel/security/** handled below\n"
 136 "  mount options=(ro, nosuid, nodev, noexec, remount, strictatime) -> /sys/fs/cgroup/,\n"
 137 "\n"
 138 "  # deny reads from debugfs\n"
 139 "  deny /sys/kernel/debug/{,**} rwklx,\n"
 140 "\n"
 141 "  # allow paths to be made slave, shared, private or unbindable\n"
 142 "  # FIXME: This currently doesn't work due to the apparmor parser treating those as allowing all mounts.\n"
 143 "#  mount options=(rw,make-slave) -> **,\n"
 144 "#  mount options=(rw,make-rslave) -> **,\n"
 145 "#  mount options=(rw,make-shared) -> **,\n"
 146 "#  mount options=(rw,make-rshared) -> **,\n"
 147 "#  mount options=(rw,make-private) -> **,\n"
 148 "#  mount options=(rw,make-rprivate) -> **,\n"
 149 "#  mount options=(rw,make-unbindable) -> **,\n"
 150 "#  mount options=(rw,make-runbindable) -> **,\n"
 151 "\n"
 152 "  # allow bind-mounts of anything except /proc, /sys and /dev\n"
 153 "  mount options=(rw,bind) /[^spd]*{,/**},\n"
 154 "  mount options=(rw,bind) /d[^e]*{,/**},\n"
 155 "  mount options=(rw,bind) /de[^v]*{,/**},\n"
 156 "  mount options=(rw,bind) /dev/.[^l]*{,/**},\n"
 157 "  mount options=(rw,bind) /dev/.l[^x]*{,/**},\n"
 158 "  mount options=(rw,bind) /dev/.lx[^c]*{,/**},\n"
 159 "  mount options=(rw,bind) /dev/.lxc?*{,/**},\n"
 160 "  mount options=(rw,bind) /dev/[^.]*{,/**},\n"
 161 "  mount options=(rw,bind) /dev?*{,/**},\n"
 162 "  mount options=(rw,bind) /p[^r]*{,/**},\n"
 163 "  mount options=(rw,bind) /pr[^o]*{,/**},\n"
 164 "  mount options=(rw,bind) /pro[^c]*{,/**},\n"
 165 "  mount options=(rw,bind) /proc?*{,/**},\n"
 166 "  mount options=(rw,bind) /s[^y]*{,/**},\n"
 167 "  mount options=(rw,bind) /sy[^s]*{,/**},\n"
 168 "  mount options=(rw,bind) /sys?*{,/**},\n"
 169 "\n"
 170 "  # allow read-only bind-mounts of anything except /proc, /sys and /dev\n"
 171 "  mount options=(ro,remount,bind) -> /[^spd]*{,/**},\n"
 172 "  mount options=(ro,remount,bind) -> /d[^e]*{,/**},\n"
 173 "  mount options=(ro,remount,bind) -> /de[^v]*{,/**},\n"
 174 "  mount options=(ro,remount,bind) -> /dev/.[^l]*{,/**},\n"
 175 "  mount options=(ro,remount,bind) -> /dev/.l[^x]*{,/**},\n"
 176 "  mount options=(ro,remount,bind) -> /dev/.lx[^c]*{,/**},\n"
 177 "  mount options=(ro,remount,bind) -> /dev/.lxc?*{,/**},\n"
 178 "  mount options=(ro,remount,bind) -> /dev/[^.]*{,/**},\n"
 179 "  mount options=(ro,remount,bind) -> /dev?*{,/**},\n"
 180 "  mount options=(ro,remount,bind) -> /p[^r]*{,/**},\n"
 181 "  mount options=(ro,remount,bind) -> /pr[^o]*{,/**},\n"
 182 "  mount options=(ro,remount,bind) -> /pro[^c]*{,/**},\n"
 183 "  mount options=(ro,remount,bind) -> /proc?*{,/**},\n"
 184 "  mount options=(ro,remount,bind) -> /s[^y]*{,/**},\n"
 185 "  mount options=(ro,remount,bind) -> /sy[^s]*{,/**},\n"
 186 "  mount options=(ro,remount,bind) -> /sys?*{,/**},\n"
 187 "\n"
 188 "  # allow moving mounts except for /proc, /sys and /dev\n"
 189 "  mount options=(rw,move) /[^spd]*{,/**},\n"
 190 "  mount options=(rw,move) /d[^e]*{,/**},\n"
 191 "  mount options=(rw,move) /de[^v]*{,/**},\n"
 192 "  mount options=(rw,move) /dev/.[^l]*{,/**},\n"
 193 "  mount options=(rw,move) /dev/.l[^x]*{,/**},\n"
 194 "  mount options=(rw,move) /dev/.lx[^c]*{,/**},\n"
 195 "  mount options=(rw,move) /dev/.lxc?*{,/**},\n"
 196 "  mount options=(rw,move) /dev/[^.]*{,/**},\n"
 197 "  mount options=(rw,move) /dev?*{,/**},\n"
 198 "  mount options=(rw,move) /p[^r]*{,/**},\n"
 199 "  mount options=(rw,move) /pr[^o]*{,/**},\n"
 200 "  mount options=(rw,move) /pro[^c]*{,/**},\n"
 201 "  mount options=(rw,move) /proc?*{,/**},\n"
 202 "  mount options=(rw,move) /s[^y]*{,/**},\n"
 203 "  mount options=(rw,move) /sy[^s]*{,/**},\n"
 204 "  mount options=(rw,move) /sys?*{,/**},\n"
 205 "\n"
 206 "  # generated by: lxc-generate-aa-rules.py container-rules.base\n"
 207 "  deny /proc/sys/[^kn]*{,/**} wklx,\n"
 208 "  deny /proc/sys/k[^e]*{,/**} wklx,\n"
 209 "  deny /proc/sys/ke[^r]*{,/**} wklx,\n"
 210 "  deny /proc/sys/ker[^n]*{,/**} wklx,\n"
 211 "  deny /proc/sys/kern[^e]*{,/**} wklx,\n"
 212 "  deny /proc/sys/kerne[^l]*{,/**} wklx,\n"
 213 "  deny /proc/sys/kernel/[^smhd]*{,/**} wklx,\n"
 214 "  deny /proc/sys/kernel/d[^o]*{,/**} wklx,\n"
 215 "  deny /proc/sys/kernel/do[^m]*{,/**} wklx,\n"
 216 "  deny /proc/sys/kernel/dom[^a]*{,/**} wklx,\n"
 217 "  deny /proc/sys/kernel/doma[^i]*{,/**} wklx,\n"
 218 "  deny /proc/sys/kernel/domai[^n]*{,/**} wklx,\n"
 219 "  deny /proc/sys/kernel/domain[^n]*{,/**} wklx,\n"
 220 "  deny /proc/sys/kernel/domainn[^a]*{,/**} wklx,\n"
 221 "  deny /proc/sys/kernel/domainna[^m]*{,/**} wklx,\n"
 222 "  deny /proc/sys/kernel/domainnam[^e]*{,/**} wklx,\n"
 223 "  deny /proc/sys/kernel/domainname?*{,/**} wklx,\n"
 224 "  deny /proc/sys/kernel/h[^o]*{,/**} wklx,\n"
 225 "  deny /proc/sys/kernel/ho[^s]*{,/**} wklx,\n"
 226 "  deny /proc/sys/kernel/hos[^t]*{,/**} wklx,\n"
 227 "  deny /proc/sys/kernel/host[^n]*{,/**} wklx,\n"
 228 "  deny /proc/sys/kernel/hostn[^a]*{,/**} wklx,\n"
 229 "  deny /proc/sys/kernel/hostna[^m]*{,/**} wklx,\n"
 230 "  deny /proc/sys/kernel/hostnam[^e]*{,/**} wklx,\n"
 231 "  deny /proc/sys/kernel/hostname?*{,/**} wklx,\n"
 232 "  deny /proc/sys/kernel/m[^s]*{,/**} wklx,\n"
 233 "  deny /proc/sys/kernel/ms[^g]*{,/**} wklx,\n"
 234 "  deny /proc/sys/kernel/msg*/** wklx,\n"
 235 "  deny /proc/sys/kernel/s[^he]*{,/**} wklx,\n"
 236 "  deny /proc/sys/kernel/se[^m]*{,/**} wklx,\n"
 237 "  deny /proc/sys/kernel/sem*/** wklx,\n"
 238 "  deny /proc/sys/kernel/sh[^m]*{,/**} wklx,\n"
 239 "  deny /proc/sys/kernel/shm*/** wklx,\n"
 240 "  deny /proc/sys/kernel?*{,/**} wklx,\n"
 241 "  deny /proc/sys/n[^e]*{,/**} wklx,\n"
 242 "  deny /proc/sys/ne[^t]*{,/**} wklx,\n"
 243 "  deny /proc/sys/net?*{,/**} wklx,\n"
 244 "  deny /sys/[^fdck]*{,/**} wklx,\n"
 245 "  deny /sys/c[^l]*{,/**} wklx,\n"
 246 "  deny /sys/cl[^a]*{,/**} wklx,\n"
 247 "  deny /sys/cla[^s]*{,/**} wklx,\n"
 248 "  deny /sys/clas[^s]*{,/**} wklx,\n"
 249 "  deny /sys/class/[^n]*{,/**} wklx,\n"
 250 "  deny /sys/class/n[^e]*{,/**} wklx,\n"
 251 "  deny /sys/class/ne[^t]*{,/**} wklx,\n"
 252 "  deny /sys/class/net?*{,/**} wklx,\n"
 253 "  deny /sys/class?*{,/**} wklx,\n"
 254 "  deny /sys/d[^e]*{,/**} wklx,\n"
 255 "  deny /sys/de[^v]*{,/**} wklx,\n"
 256 "  deny /sys/dev[^i]*{,/**} wklx,\n"
 257 "  deny /sys/devi[^c]*{,/**} wklx,\n"
 258 "  deny /sys/devic[^e]*{,/**} wklx,\n"
 259 "  deny /sys/device[^s]*{,/**} wklx,\n"
 260 "  deny /sys/devices/[^v]*{,/**} wklx,\n"
 261 "  deny /sys/devices/v[^i]*{,/**} wklx,\n"
 262 "  deny /sys/devices/vi[^r]*{,/**} wklx,\n"
 263 "  deny /sys/devices/vir[^t]*{,/**} wklx,\n"
 264 "  deny /sys/devices/virt[^u]*{,/**} wklx,\n"
 265 "  deny /sys/devices/virtu[^a]*{,/**} wklx,\n"
 266 "  deny /sys/devices/virtua[^l]*{,/**} wklx,\n"
 267 "  deny /sys/devices/virtual/[^n]*{,/**} wklx,\n"
 268 "  deny /sys/devices/virtual/n[^e]*{,/**} wklx,\n"
 269 "  deny /sys/devices/virtual/ne[^t]*{,/**} wklx,\n"
 270 "  deny /sys/devices/virtual/net?*{,/**} wklx,\n"
 271 "  deny /sys/devices/virtual?*{,/**} wklx,\n"
 272 "  deny /sys/devices?*{,/**} wklx,\n"
 273 "  deny /sys/f[^s]*{,/**} wklx,\n"
 274 "  deny /sys/fs/[^c]*{,/**} wklx,\n"
 275 "  deny /sys/fs/c[^g]*{,/**} wklx,\n"
 276 "  deny /sys/fs/cg[^r]*{,/**} wklx,\n"
 277 "  deny /sys/fs/cgr[^o]*{,/**} wklx,\n"
 278 "  deny /sys/fs/cgro[^u]*{,/**} wklx,\n"
 279 "  deny /sys/fs/cgrou[^p]*{,/**} wklx,\n"
 280 "  deny /sys/fs/cgroup?*{,/**} wklx,\n"
 281 "  deny /sys/fs?*{,/**} wklx,\n"
 282 ;
 283
 284 static const char AA_PROFILE_UNIX_SOCKETS[] =
 285 "\n"
 286 "  ### Feature: unix\n"
 287 "  # Allow receive via unix sockets from anywhere\n"
 288 "  unix (receive),\n"
 289 "\n"
 290 "  # Allow all unix sockets in the container\n"
 291 "  unix peer=(label=@{profile_name}),\n"
 292 ;
 293
 294 static const char AA_PROFILE_CGROUP_NAMESPACES[] =
 295 "\n"
 296 "  ### Feature: cgroup namespace\n"
 297 "  mount fstype=cgroup -> /sys/fs/cgroup/**,\n"
 298 "  mount fstype=cgroup2 -> /sys/fs/cgroup/**,\n"
 299 ;
 300
 301 /* '_BASE' because we still need to append generated change_profile rules */
 302 static const char AA_PROFILE_STACKING_BASE[] =
 303 "\n"
 304 "  ### Feature: apparmor stacking\n"
 305 "  ### Configuration: apparmor profile loading (in namespace)\n"
 306 "  deny /sys/k[^e]*{,/**} wklx,\n"
 307 "  deny /sys/ke[^r]*{,/**} wklx,\n"
 308 "  deny /sys/ker[^n]*{,/**} wklx,\n"
 309 "  deny /sys/kern[^e]*{,/**} wklx,\n"
 310 "  deny /sys/kerne[^l]*{,/**} wklx,\n"
 311 "  deny /sys/kernel/[^s]*{,/**} wklx,\n"
 312 "  deny /sys/kernel/s[^e]*{,/**} wklx,\n"
 313 "  deny /sys/kernel/se[^c]*{,/**} wklx,\n"
 314 "  deny /sys/kernel/sec[^u]*{,/**} wklx,\n"
 315 "  deny /sys/kernel/secu[^r]*{,/**} wklx,\n"
 316 "  deny /sys/kernel/secur[^i]*{,/**} wklx,\n"
 317 "  deny /sys/kernel/securi[^t]*{,/**} wklx,\n"
 318 "  deny /sys/kernel/securit[^y]*{,/**} wklx,\n"
 319 "  deny /sys/kernel/security/[^a]*{,/**} wklx,\n"
 320 "  deny /sys/kernel/security/a[^p]*{,/**} wklx,\n"
 321 "  deny /sys/kernel/security/ap[^p]*{,/**} wklx,\n"
 322 "  deny /sys/kernel/security/app[^a]*{,/**} wklx,\n"
 323 "  deny /sys/kernel/security/appa[^r]*{,/**} wklx,\n"
 324 "  deny /sys/kernel/security/appar[^m]*{,/**} wklx,\n"
 325 "  deny /sys/kernel/security/apparm[^o]*{,/**} wklx,\n"
 326 "  deny /sys/kernel/security/apparmo[^r]*{,/**} wklx,\n"
 327 "  deny /sys/kernel/security/apparmor?*{,/**} wklx,\n"
 328 "  deny /sys/kernel/security?*{,/**} wklx,\n"
 329 "  deny /sys/kernel?*{,/**} wklx,\n"
 330 ;
 331
 332 static const char AA_PROFILE_NO_STACKING[] =
 333 "\n"
 334 "  ### Feature: apparmor stacking (not present)\n"
 335 "  deny /sys/k*{,/**} rwklx,\n"
 336 ;
 337
 338 /* '_BASE' because we need to append change_profile for stacking */
 339 static const char AA_PROFILE_NESTING_BASE[] =
 340 "\n"
 341 "  ### Configuration: nesting\n"
 342 "  pivot_root,\n"
 343 "  ptrace,\n"
 344 "  signal,\n"
 345 "\n"
 346    /* NOTE: See conf.c's "nesting_helpers" for details. */
 347 "  deny /dev/.lxc/proc/** rw,\n"
 348 "  deny /dev/.lxc/sys/** rw,\n"
 349 "\n"
 350 "  mount fstype=proc -> /usr/lib/*/lxc/**,\n"
 351 "  mount fstype=sysfs -> /usr/lib/*/lxc/**,\n"
 352 "  mount options=(rw,bind),\n"
 353 "  mount options=(rw,rbind),\n"
 354 "  mount options=(rw,make-rshared),\n"
 355 "\n"
 356    /* FIXME: What's the state here on apparmor's side? */
 357 "  # there doesn't seem to be a way to ask for:\n"
 358 "  # mount options=(ro,nosuid,nodev,noexec,remount,bind),\n"
 359 "  # as we always get mount to $cdir/proc/sys with those flags denied\n"
 360 "  # So allow all mounts until that is straightened out:\n"
 361 "  mount,\n"
 362 ;
 363
 364 static const char AA_PROFILE_UNPRIVILEGED[] =
 365 "\n"
 366 "  ### Configuration: unprivileged container\n"
 367 "  pivot_root,\n"
 368 "\n"
 369 "  # Allow modifying mount propagation\n"
 370 "  mount options=(rw,make-slave) -> **,\n"
 371 "  mount options=(rw,make-rslave) -> **,\n"
 372 "  mount options=(rw,make-shared) -> **,\n"
 373 "  mount options=(rw,make-rshared) -> **,\n"
 374 "  mount options=(rw,make-private) -> **,\n"
 375 "  mount options=(rw,make-rprivate) -> **,\n"
 376 "  mount options=(rw,make-unbindable) -> **,\n"
 377 "  mount options=(rw,make-runbindable) -> **,\n"
 378 "\n"
 379 "  # Allow all bind-mounts\n"
 380 "  mount options=(rw,bind),\n"
 381 "  mount options=(rw,rbind),\n"
 382 "\n"
 383 "  # Allow remounting things read-only\n"
 384 "  mount options=(ro,remount),\n"
 385 ;
 386
 387 static bool check_mount_feature_enabled(void)
 388 {
 389         return mount_features_enabled == 1;
 390 }
 391
 392 static void load_mount_features_enabled(void)
 393 {
 394         struct stat statbuf;
 395         int ret;
 396
 397         ret = stat(AA_MOUNT_RESTR, &statbuf);
 398         if (ret == 0)
 399                 mount_features_enabled = 1;
 400 }
 401
 402 /* aa_getcon is not working right now.  Use our hand-rolled version below */
 403 static int apparmor_enabled(void)
 404 {
 405         FILE *fin;
 406         char e;
 407         int ret;
 408
 409         fin = fopen_cloexec(AA_ENABLED_FILE, "r");
 410         if (!fin)
 411                 return 0;
 412         ret = fscanf(fin, "%c", &e);
 413         fclose(fin);
 414         if (ret == 1 && e == 'Y') {
 415                 load_mount_features_enabled();
 416                 return 1;
 417         }
 418
 419         return 0;
 420 }
 421
 422 static char *apparmor_process_label_get(pid_t pid)
 423 {
 424         char path[100], *space;
 425         int ret;
 426         char *buf = NULL, *newbuf;
 427         int sz = 0;
 428         FILE *f;
 429
 430         ret = snprintf(path, 100, "/proc/%d/attr/current", pid);
 431         if (ret < 0 || ret >= 100) {
 432                 ERROR("path name too long");
 433                 return NULL;
 434         }
 435 again:
 436         f = fopen_cloexec(path, "r");
 437         if (!f) {
 438                 SYSERROR("opening %s", path);
 439                 free(buf);
 440                 return NULL;
 441         }
 442         sz += 1024;
 443         newbuf = realloc(buf, sz);
 444         if (!newbuf) {
 445                 free(buf);
 446                 ERROR("out of memory");
 447                 fclose(f);
 448                 return NULL;
 449         }
 450         buf = newbuf;
 451         memset(buf, 0, sz);
 452         ret = fread(buf, 1, sz - 1, f);
 453         fclose(f);
 454         if (ret < 0) {
 455                 ERROR("reading %s", path);
 456                 free(buf);
 457                 return NULL;
 458         }
 459         if (ret >= sz)
 460                 goto again;
 461         space = strchr(buf, '\n');
 462         if (space)
 463                 *space = '\0';
 464         space = strchr(buf, ' ');
 465         if (space)
 466                 *space = '\0';
 467         return buf;
 468 }
 469
 470 /*
 471  * Probably makes sense to reorganize these to only read
 472  * the label once
 473  */
 474 static bool apparmor_am_unconfined(void)
 475 {
 476         char *p = apparmor_process_label_get(lxc_raw_getpid());
 477         bool ret = false;
 478         if (!p || strcmp(p, "unconfined") == 0)
 479                 ret = true;
 480         free(p);
 481         return ret;
 482 }
 483
 484 static bool aa_needs_transition(char *curlabel)
 485 {
 486         if (!curlabel)
 487                 return false;
 488         if (strcmp(curlabel, "unconfined") == 0)
 489                 return false;
 490         if (strcmp(curlabel, "/usr/bin/lxc-start") == 0)
 491                 return false;
 492         return true;
 493 }
 494
 495 static inline void uint64hex(char *buf, uint64_t num)
 496 {
 497         size_t i;
 498
 499         buf[16] = 0;
 500         for (i = 16; i--;) {
 501                 char c = (char)(num & 0xf);
 502                 buf[i] = c + (c < 0xa ? '0' : 'a' - 0xa);
 503                 num >>= 4;
 504         }
 505 }
 506
 507 static inline char *shorten_apparmor_name(char *name)
 508 {
 509         size_t len = strlen(name);
 510         if (len + 7 > 253) {
 511                 uint64_t hash;
 512                 hash = fnv_64a_buf(name, len, FNV1A_64_INIT);
 513                 name = must_realloc(name, 16 + 1);
 514                 uint64hex(name, hash);
 515         }
 516
 517         return name;
 518 }
 519
 520 /* Replace slashes with hyphens */
 521 static inline void sanitize_path(char *path)
 522 {
 523         size_t i;
 524
 525         for (i = 0; path[i]; i++)
 526                 if (path[i] == '/')
 527                         path[i] = '-';
 528 }
 529
 530 static inline char *apparmor_dir(const char *ctname, const char *lxcpath)
 531 {
 532         return must_make_path(lxcpath, ctname, "apparmor", NULL);
 533 }
 534
 535
 536 static inline char *apparmor_profile_full(const char *ctname, const char *lxcpath)
 537 {
 538         return shorten_apparmor_name(must_concat("lxc-", ctname, "_<", lxcpath, ">", NULL));
 539 }
 540
 541 /* Like apparmor_profile_full() but with slashes replaced by hyphens */
 542 static inline char *apparmor_namespace(const char *ctname, const char *lxcpath)
 543 {
 544         char *full;
 545
 546         full = apparmor_profile_full(ctname, lxcpath);
 547         sanitize_path(full);
 548
 549         return full;
 550 }
 551
 552 /* FIXME: This is currently run only in the context of a constructor (via the
 553  * initial lsm_init() called due to its __attribute__((constructor)), so we
 554  * do not have ERROR/... macros available, so there are some fprintf(stderr)s
 555  * in there.
 556  */
 557 static bool check_apparmor_parser_version()
 558 {
 559         struct lxc_popen_FILE *parserpipe;
 560         int rc;
 561         int major = 0, minor = 0, micro = 0;
 562
 563         parserpipe = lxc_popen("apparmor_parser --version");
 564         if (!parserpipe) {
 565                 fprintf(stderr, "Failed to run check for apparmor_parser\n");
 566                 return false;
 567         }
 568
 569         rc = fscanf(parserpipe->f, "AppArmor parser version %d.%d.%d", &major, &minor, &micro);
 570         if (rc < 1) {
 571                 lxc_pclose(parserpipe);
 572                 /* We stay silent for now as this most likely means the shell
 573                  * lxc_popen executed failed to find the apparmor_parser binary.
 574                  * See the FIXME comment above for details.
 575                  */
 576                 return false;
 577         }
 578
 579         rc = lxc_pclose(parserpipe);
 580         if (rc < 0) {
 581                 fprintf(stderr, "Error waiting for child process\n");
 582                 return false;
 583         }
 584         if (rc != 0) {
 585                 fprintf(stderr, "'apparmor_parser --version' executed with an error status\n");
 586                 return false;
 587         }
 588
 589         aa_supports_unix = (major > 2) ||
 590                            (major == 2 && minor > 10) ||
 591                            (major == 2 && minor == 10 && micro >= 95);
 592
 593         return true;
 594 }
 595
 596 static bool file_is_yes(const char *path)
 597 {
 598         ssize_t rd;
 599         int fd;
 600         char buf[8]; /* we actually just expect "yes" or "no" */
 601
 602         fd = open(path, O_RDONLY | O_CLOEXEC);
 603         if (fd < 0)
 604                 return false;
 605
 606         rd = lxc_read_nointr(fd, buf, sizeof(buf));
 607         close(fd);
 608
 609         return rd >= 4 && strncmp(buf, "yes\n", 4) == 0;
 610 }
 611
 612 static bool apparmor_can_stack()
 613 {
 614         int major, minor, scanned;
 615         FILE *f;
 616
 617         if (!file_is_yes("/sys/kernel/security/apparmor/features/domain/stack"))
 618                 return false;
 619
 620         f = fopen_cloexec("/sys/kernel/security/apparmor/features/domain/version", "r");
 621         if (!f)
 622                 return false;
 623
 624         scanned = fscanf(f, "%d.%d", &major, &minor);
 625         fclose(f);
 626         if (scanned != 2)
 627                 return false;
 628
 629         return major > 1 || (major == 1 && minor >= 2);
 630 }
 631
 632 static void must_append_sized_full(char **buf, size_t *bufsz, const char *data,
 633                                    size_t size, bool append_newline)
 634 {
 635         size_t newsize = *bufsz + size;
 636
 637         if (append_newline)
 638                 ++newsize;
 639
 640         *buf = must_realloc(*buf, newsize);
 641         memcpy(*buf + *bufsz, data, size);
 642
 643         if (append_newline)
 644                 (*buf)[newsize - 1] = '\n';
 645
 646         *bufsz = newsize;
 647 }
 648
 649 static void must_append_sized(char **buf, size_t *bufsz, const char *data, size_t size)
 650 {
 651         return must_append_sized_full(buf, bufsz, data, size, false);
 652 }
 653
 654 static bool is_privileged(struct lxc_conf *conf)
 655 {
 656         return lxc_list_empty(&conf->id_map);
 657 }
 658
 659 static char *get_apparmor_profile_content(struct lxc_conf *conf, const char *lxcpath)
 660 {
 661         char *profile, *profile_name_full;
 662         size_t size;
 663         struct lxc_list *it;
 664
 665         profile_name_full = apparmor_profile_full(conf->name, lxcpath);
 666
 667         profile = must_concat(
 668 "#include <tunables/global>\n"
 669 "profile \"", profile_name_full, "\" flags=(attach_disconnected,mediate_deleted) {\n",
 670                               NULL);
 671         size = strlen(profile);
 672
 673         must_append_sized(&profile, &size, AA_PROFILE_BASE,
 674                           STRARRAYLEN(AA_PROFILE_BASE));
 675
 676         if (aa_supports_unix)
 677                 must_append_sized(&profile, &size, AA_PROFILE_UNIX_SOCKETS,
 678                                   STRARRAYLEN(AA_PROFILE_UNIX_SOCKETS));
 679
 680         if (file_exists("/proc/self/ns/cgroup"))
 681                 must_append_sized(&profile, &size, AA_PROFILE_CGROUP_NAMESPACES,
 682                                   STRARRAYLEN(AA_PROFILE_CGROUP_NAMESPACES));
 683
 684         if (aa_can_stack && !aa_is_stacked) {
 685                 char *namespace, *temp;
 686
 687                 must_append_sized(&profile, &size, AA_PROFILE_STACKING_BASE,
 688                                   STRARRAYLEN(AA_PROFILE_STACKING_BASE));
 689
 690                 namespace = apparmor_namespace(conf->name, lxcpath);
 691                 temp = must_concat("  change_profile -> \":", namespace, ":*\",\n"
 692                                    "  change_profile -> \":", namespace, "://*\",\n",
 693                                    NULL);
 694                 free(namespace);
 695
 696                 must_append_sized(&profile, &size, temp, strlen(temp));
 697                 free(temp);
 698         } else {
 699                 must_append_sized(&profile, &size, AA_PROFILE_NO_STACKING,
 700                                   STRARRAYLEN(AA_PROFILE_NO_STACKING));
 701         }
 702
 703         if (conf->lsm_aa_allow_nesting) {
 704                 must_append_sized(&profile, &size, AA_PROFILE_NESTING_BASE,
 705                                   STRARRAYLEN(AA_PROFILE_NESTING_BASE));
 706
 707                 if (!aa_can_stack || aa_is_stacked) {
 708                         char *temp;
 709
 710                         temp = must_concat("  change_profile -> \"",
 711                                            profile_name_full, "\",\n", NULL);
 712                         must_append_sized(&profile, &size, temp, strlen(temp));
 713                         free(temp);
 714                 }
 715         }
 716
 717         if (!is_privileged(conf) || am_host_unpriv())
 718                 must_append_sized(&profile, &size, AA_PROFILE_UNPRIVILEGED,
 719                                   STRARRAYLEN(AA_PROFILE_UNPRIVILEGED));
 720
 721         lxc_list_for_each(it, &conf->lsm_aa_raw) {
 722                 const char *line = it->elem;
 723
 724                 must_append_sized_full(&profile, &size, line, strlen(line), true);
 725         }
 726
 727         /* include terminating \0 byte */
 728         must_append_sized(&profile, &size, "}\n", 3);
 729
 730         free(profile_name_full);
 731
 732         return profile;
 733 }
 734
 735 /*
 736  * apparmor_parser creates a cache file using the parsed file's name as a name.
 737  * This means there may be multiple containers with the same name but different
 738  * lxcpaths. Therefore we need a sanitized version of the complete profile name
 739  * as profile file-name.
 740  * We already get this exactly from apparmor_namespace().
 741  */
 742 static char *make_apparmor_profile_path(const char *ctname, const char *lxcpath)
 743 {
 744         char *ret, *filename;
 745
 746         filename = apparmor_namespace(ctname, lxcpath);
 747         ret = must_make_path(lxcpath, ctname, "apparmor", filename, NULL);
 748         free(filename);
 749
 750         return ret;
 751 }
 752
 753 static char *make_apparmor_namespace_path(const char *ctname, const char *lxcpath)
 754 {
 755         char *ret, *namespace;
 756
 757         namespace = apparmor_namespace(ctname, lxcpath);
 758         ret = must_make_path("/sys/kernel/security/apparmor/policy/namespaces", namespace, NULL);
 759         free(namespace);
 760
 761         return ret;
 762 }
 763
 764 static bool make_apparmor_namespace(struct lxc_conf *conf, const char *lxcpath)
 765 {
 766         char *path;
 767
 768         if (!aa_can_stack || aa_is_stacked)
 769                 return true;
 770
 771         path = make_apparmor_namespace_path(conf->name, lxcpath);
 772         errno = 0;
 773         if (mkdir(path, 0755) < 0 && errno != EEXIST) {
 774                 SYSERROR("Error creating AppArmor namespace: %s", path);
 775                 free(path);
 776                 return false;
 777         }
 778         free(path);
 779
 780         return true;
 781 }
 782
 783 static void remove_apparmor_namespace(struct lxc_conf *conf, const char *lxcpath)
 784 {
 785         char *path;
 786
 787         path = make_apparmor_namespace_path(conf->name, lxcpath);
 788         if (rmdir(path) != 0)
 789                 SYSERROR("Error removing AppArmor namespace");
 790         free(path);
 791 }
 792
 793 struct apparmor_parser_args {
 794         char cmd;
 795         char *file;
 796 };
 797
 798 static int apparmor_parser_exec(void *data)
 799 {
 800         struct apparmor_parser_args *args = data;
 801         char cmdbuf[] = { '-', args->cmd, 'W', 'L', 0 };
 802
 803         execlp("apparmor_parser", "apparmor_parser", cmdbuf, APPARMOR_CACHE_DIR, args->file, NULL);
 804
 805         return -1;
 806 }
 807
 808 static int run_apparmor_parser(char command,
 809                                struct lxc_conf *conf,
 810                                const char *lxcpath)
 811 {
 812         char output[PATH_MAX];
 813         int ret;
 814         struct apparmor_parser_args args = {
 815                 .cmd = command,
 816                 .file = make_apparmor_profile_path(conf->name, lxcpath),
 817         };
 818
 819         ret = run_command(output, sizeof(output), apparmor_parser_exec, (void*)&args);
 820         if (ret < 0) {
 821                 ERROR("Failed to run apparmor_parser on \"%s\": %s", args.file, output);
 822                 ret = -1;
 823         }
 824
 825
 826         free(args.file);
 827         return ret;
 828 }
 829
 830 static void remove_apparmor_profile(struct lxc_conf *conf, const char *lxcpath)
 831 {
 832         char *path;
 833
 834         /* It's ok if these deletes fail: if the container was never started,
 835          * we'll have never written a profile or cached it.
 836          */
 837
 838         path = make_apparmor_profile_path(conf->name, lxcpath);
 839         (void)unlink(path);
 840         free(path);
 841
 842         /* Also remove the apparmor/ subdirectory */
 843         path = apparmor_dir(conf->name, lxcpath);
 844         (void)rmdir(path);
 845         free(path);
 846 }
 847
 848 static int load_apparmor_profile(struct lxc_conf *conf, const char *lxcpath)
 849 {
 850         struct stat profile_sb;
 851         size_t content_len;
 852         int ret = -1;
 853         size_t old_len = 0;
 854         char *profile_path = NULL, *old_content = NULL, *new_content = NULL;
 855         int profile_fd = -1;
 856
 857         if (!make_apparmor_namespace(conf, lxcpath))
 858                 return -1;
 859
 860         /* In order to avoid forcing a profile parse (potentially slow) on
 861          * every container start, let's use apparmor's binary policy cache,
 862          * which checks mtime of the files to figure out if the policy needs to
 863          * be regenerated.
 864          *
 865          * Since it uses mtimes, we shouldn't just always write out our local
 866          * apparmor template; instead we should check to see whether the
 867          * template is the same as ours. If it isn't we should write our
 868          * version out so that the new changes are reflected and we definitely
 869          * force a recompile.
 870          */
 871
 872         profile_path = make_apparmor_profile_path(conf->name, lxcpath);
 873         profile_fd = open(profile_path, O_RDONLY | O_CLOEXEC);
 874         if (profile_fd >= 0) {
 875                 if (fstat(profile_fd, &profile_sb) < 0) {
 876                         SYSERROR("Error accessing old profile from %s",
 877                                  profile_path);
 878                         goto out;
 879                 }
 880                 old_len = profile_sb.st_size;
 881                 old_content = lxc_strmmap(NULL, old_len, PROT_READ,
 882                                           MAP_PRIVATE, profile_fd, 0);
 883                 if (!old_content) {
 884                         SYSERROR("Failed to mmap old profile from %s",
 885                                  profile_path);
 886                         goto out;
 887                 }
 888         } else if (errno != ENOENT) {
 889                 SYSERROR("Error reading old profile from %s", profile_path);
 890                 goto out;
 891         }
 892
 893         new_content = get_apparmor_profile_content(conf, lxcpath);
 894         if (!new_content)
 895                 goto out;
 896
 897         content_len = strlen(new_content);
 898
 899         if (!old_content || old_len != content_len || memcmp(old_content, new_content, content_len) != 0) {
 900                 char *path;
 901
 902                 ret = mkdir_p(APPARMOR_CACHE_DIR, 0755);
 903                 if (ret < 0) {
 904                         SYSERROR("Error creating AppArmor profile cache directory " APPARMOR_CACHE_DIR);
 905                         goto out;
 906                 }
 907
 908                 path = apparmor_dir(conf->name, lxcpath);
 909                 ret = mkdir_p(path, 0755);
 910                 if (ret < 0) {
 911                         SYSERROR("Error creating AppArmor profile directory: %s", path);
 912                         free(path);
 913                         goto out;
 914                 }
 915                 free(path);
 916
 917                 ret = lxc_write_to_file(profile_path, new_content, content_len, false, 0600);
 918                 if (ret < 0) {
 919                         SYSERROR("Error writing profile to %s", profile_path);
 920                         goto out;
 921                 }
 922         }
 923
 924         ret = run_apparmor_parser(AA_CMD_LOAD, conf, lxcpath);
 925         if (ret != 0)
 926                 goto out_remove_profile;
 927
 928         conf->lsm_aa_profile_created = true;
 929
 930         goto out_ok;
 931
 932 out_remove_profile:
 933         remove_apparmor_profile(conf, lxcpath);
 934 out:
 935         remove_apparmor_namespace(conf, lxcpath);
 936 out_ok:
 937         if (profile_fd >= 0) {
 938                 if (old_content)
 939                         lxc_strmunmap(old_content, old_len);
 940                 close(profile_fd);
 941         }
 942         free(profile_path);
 943         free(new_content);
 944         return ret;
 945 }
 946
 947 /*
 948  * Ensure that the container's policy namespace is unloaded to free kernel
 949  * memory. This does not delete the policy from disk or cache.
 950  */
 951 static void apparmor_cleanup(struct lxc_conf *conf, const char *lxcpath)
 952 {
 953         if (!aa_admin)
 954                 return;
 955
 956         if (!conf->lsm_aa_profile_created)
 957                 return;
 958
 959         remove_apparmor_namespace(conf, lxcpath);
 960         (void)run_apparmor_parser(AA_CMD_UNLOAD, conf, lxcpath);
 961
 962         remove_apparmor_profile(conf, lxcpath);
 963 }
 964
 965 static int apparmor_prepare(struct lxc_conf *conf, const char *lxcpath)
 966 {
 967         int ret = -1;
 968         const char *label;
 969         char *curlabel = NULL, *genlabel = NULL;
 970
 971         if (!aa_enabled) {
 972                 ERROR("AppArmor not enabled");
 973                 return -1;
 974         }
 975
 976         label = conf->lsm_aa_profile;
 977
 978         /* user may request that we just ignore apparmor */
 979         if (label && strcmp(label, AA_UNCHANGED) == 0) {
 980                 INFO("AppArmor profile unchanged per user request");
 981                 conf->lsm_aa_profile_computed = must_copy_string(label);
 982                 return 0;
 983         }
 984
 985         if (label && strcmp(label, AA_GENERATED) == 0) {
 986                 if (!aa_parser_available) {
 987                         ERROR("Cannot use generated profile: apparmor_parser not available");
 988                         goto out;
 989                 }
 990
 991                 /* auto-generate profile based on available/requested security features */
 992                 if (load_apparmor_profile(conf, lxcpath) != 0) {
 993                         ERROR("Failed to load generated AppArmor profile");
 994                         goto out;
 995                 }
 996
 997                 genlabel = apparmor_profile_full(conf->name, lxcpath);
 998                 if (!genlabel) {
 999                         ERROR("Failed to build AppArmor profile name");
1000                         goto out;
1001                 }
1002
1003                 if (aa_can_stack && !aa_is_stacked) {
1004                         char *namespace = apparmor_namespace(conf->name, lxcpath);
1005                         size_t llen = strlen(genlabel);
1006                         must_append_sized(&genlabel, &llen, "//&:", STRARRAYLEN("//&:"));
1007                         must_append_sized(&genlabel, &llen, namespace, strlen(namespace));
1008                         must_append_sized(&genlabel, &llen, ":", STRARRAYLEN(":") + 1); /* with the nul byte */
1009                         free(namespace);
1010                 }
1011
1012                 label = genlabel;
1013         }
1014
1015         curlabel = apparmor_process_label_get(lxc_raw_getpid());
1016
1017         if (!aa_can_stack && aa_needs_transition(curlabel)) {
1018                 /* we're already confined, and stacking isn't supported */
1019
1020                 if (!label || strcmp(curlabel, label) == 0) {
1021                         /* no change requested */
1022                         ret = 0;
1023                         goto out;
1024                 }
1025
1026                 ERROR("Already AppArmor confined, but new label requested.");
1027                 goto out;
1028         }
1029
1030         if (!label) {
1031                 if (cgns_supported())
1032                         label = AA_DEF_PROFILE_CGNS;
1033                 else
1034                         label = AA_DEF_PROFILE;
1035         }
1036
1037         if (!check_mount_feature_enabled() && strcmp(label, "unconfined") != 0) {
1038                 WARN("Incomplete AppArmor support in your kernel");
1039                 if (!conf->lsm_aa_allow_incomplete) {
1040                         ERROR("If you really want to start this container, set");
1041                         ERROR("lxc.apparmor.allow_incomplete = 1");
1042                         ERROR("in your container configuration file");
1043                         goto out;
1044                 }
1045         }
1046
1047         conf->lsm_aa_profile_computed = must_copy_string(label);
1048         ret = 0;
1049
1050 out:
1051         if (genlabel) {
1052                 free(genlabel);
1053                 if (ret != 0)
1054                         apparmor_cleanup(conf, lxcpath);
1055         }
1056         free(curlabel);
1057         return ret;
1058 }
1059
1060 /*
1061  * apparmor_process_label_set: Set AppArmor process profile
1062  *
1063  * @label   : the profile to set
1064  * @conf    : the container configuration to use if @label is NULL
1065  * @default : use the default profile if @label is NULL
1066  * @on_exec : this is ignored.  Apparmor profile will be changed immediately
1067  *
1068  * Returns 0 on success, < 0 on failure
1069  *
1070  * Notes: This relies on /proc being available.
1071  */
1072 static int apparmor_process_label_set(const char *inlabel, struct lxc_conf *conf,
1073                                       bool on_exec)
1074 {
1075         int label_fd, ret;
1076         pid_t tid;
1077         const char *label;
1078
1079         if (!aa_enabled) {
1080                 ERROR("AppArmor not enabled");
1081                 return -1;
1082         }
1083
1084         label = inlabel ? inlabel : conf->lsm_aa_profile_computed;
1085         if (!label) {
1086                 ERROR("LSM wasn't prepared");
1087                 return -1;
1088         }
1089
1090         /* user may request that we just ignore apparmor */
1091         if (strcmp(label, AA_UNCHANGED) == 0) {
1092                 INFO("AppArmor profile unchanged per user request");
1093                 return 0;
1094         }
1095
1096         if (strcmp(label, "unconfined") == 0 && apparmor_am_unconfined()) {
1097                 INFO("AppArmor profile unchanged");
1098                 return 0;
1099         }
1100         tid = lxc_raw_gettid();
1101         label_fd = lsm_process_label_fd_get(tid, on_exec);
1102         if (label_fd < 0) {
1103                 SYSERROR("Failed to change AppArmor profile to %s", label);
1104                 return -1;
1105         }
1106
1107         ret = lsm_process_label_set_at(label_fd, label, on_exec);
1108         close(label_fd);
1109         if (ret < 0) {
1110                 ERROR("Failed to change AppArmor profile to %s", label);
1111                 return -1;
1112         }
1113
1114         INFO("Changed AppArmor profile to %s", label);
1115         return 0;
1116 }
1117
1118 static struct lsm_drv apparmor_drv = {
1119         .name = "AppArmor",
1120         .enabled           = apparmor_enabled,
1121         .process_label_get = apparmor_process_label_get,
1122         .process_label_set = apparmor_process_label_set,
1123         .prepare           = apparmor_prepare,
1124         .cleanup           = apparmor_cleanup,
1125 };
1126
1127 struct lsm_drv *lsm_apparmor_drv_init(void)
1128 {
1129         bool have_mac_admin = false;
1130
1131         if (!apparmor_enabled())
1132                 return NULL;
1133
1134         /* We only support generated profiles when apparmor_parser is usable */
1135         if (!check_apparmor_parser_version())
1136                 goto out;
1137
1138         aa_parser_available = true;
1139
1140         aa_can_stack = apparmor_can_stack();
1141         if (aa_can_stack)
1142                 aa_is_stacked = file_is_yes("/sys/kernel/security/apparmor/.ns_stacked");
1143
1144         #if HAVE_LIBCAP
1145         have_mac_admin = lxc_proc_cap_is_set(CAP_SETGID, CAP_EFFECTIVE);
1146         #endif
1147
1148         if (!have_mac_admin)
1149                 WARN("Per-container AppArmor profiles are disabled because the mac_admin capability is missing");
1150         else if (am_host_unpriv() && !aa_is_stacked)
1151                 WARN("Per-container AppArmor profiles are disabled because LXC is running in an unprivileged container without stacking");
1152         else
1153                 aa_admin = true;
1154
1155 out:
1156         aa_enabled = 1;
1157         return &apparmor_drv;
1158 }