src/lxc/lsm/apparmor.c

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