John Johansen | 898127c | 2010-07-29 14:48:06 -0700 | [diff] [blame] | 1 | /* |
| 2 | * AppArmor security module |
| 3 | * |
| 4 | * This file contains AppArmor policy attachment and domain transitions |
| 5 | * |
| 6 | * Copyright (C) 2002-2008 Novell/SUSE |
| 7 | * Copyright 2009-2010 Canonical Ltd. |
| 8 | * |
| 9 | * This program is free software; you can redistribute it and/or |
| 10 | * modify it under the terms of the GNU General Public License as |
| 11 | * published by the Free Software Foundation, version 2 of the |
| 12 | * License. |
| 13 | */ |
| 14 | |
| 15 | #include <linux/errno.h> |
| 16 | #include <linux/fdtable.h> |
| 17 | #include <linux/file.h> |
| 18 | #include <linux/mount.h> |
| 19 | #include <linux/syscalls.h> |
| 20 | #include <linux/tracehook.h> |
| 21 | #include <linux/personality.h> |
| 22 | |
| 23 | #include "include/audit.h" |
| 24 | #include "include/apparmorfs.h" |
| 25 | #include "include/context.h" |
| 26 | #include "include/domain.h" |
| 27 | #include "include/file.h" |
| 28 | #include "include/ipc.h" |
| 29 | #include "include/match.h" |
| 30 | #include "include/path.h" |
| 31 | #include "include/policy.h" |
| 32 | |
| 33 | /** |
| 34 | * aa_free_domain_entries - free entries in a domain table |
| 35 | * @domain: the domain table to free (MAYBE NULL) |
| 36 | */ |
| 37 | void aa_free_domain_entries(struct aa_domain *domain) |
| 38 | { |
| 39 | int i; |
| 40 | if (domain) { |
| 41 | if (!domain->table) |
| 42 | return; |
| 43 | |
| 44 | for (i = 0; i < domain->size; i++) |
| 45 | kzfree(domain->table[i]); |
| 46 | kzfree(domain->table); |
| 47 | domain->table = NULL; |
| 48 | } |
| 49 | } |
| 50 | |
| 51 | /** |
| 52 | * may_change_ptraced_domain - check if can change profile on ptraced task |
| 53 | * @task: task we want to change profile of (NOT NULL) |
| 54 | * @to_profile: profile to change to (NOT NULL) |
| 55 | * |
| 56 | * Check if the task is ptraced and if so if the tracing task is allowed |
| 57 | * to trace the new domain |
| 58 | * |
| 59 | * Returns: %0 or error if change not allowed |
| 60 | */ |
| 61 | static int may_change_ptraced_domain(struct task_struct *task, |
| 62 | struct aa_profile *to_profile) |
| 63 | { |
| 64 | struct task_struct *tracer; |
James Morris | 77c80e6 | 2010-08-02 15:49:00 +1000 | [diff] [blame^] | 65 | const struct cred *cred = NULL; |
John Johansen | 898127c | 2010-07-29 14:48:06 -0700 | [diff] [blame] | 66 | struct aa_profile *tracerp = NULL; |
| 67 | int error = 0; |
| 68 | |
| 69 | rcu_read_lock(); |
| 70 | tracer = tracehook_tracer_task(task); |
| 71 | if (tracer) { |
| 72 | /* released below */ |
| 73 | cred = get_task_cred(tracer); |
| 74 | tracerp = aa_cred_profile(cred); |
| 75 | } |
| 76 | rcu_read_unlock(); |
| 77 | |
| 78 | /* not ptraced */ |
| 79 | if (!tracer || unconfined(tracerp)) |
| 80 | goto out; |
| 81 | |
| 82 | error = aa_may_ptrace(tracer, tracerp, to_profile, PTRACE_MODE_ATTACH); |
| 83 | |
| 84 | out: |
| 85 | if (cred) |
| 86 | put_cred(cred); |
| 87 | |
| 88 | return error; |
| 89 | } |
| 90 | |
| 91 | /** |
| 92 | * change_profile_perms - find permissions for change_profile |
| 93 | * @profile: the current profile (NOT NULL) |
| 94 | * @ns: the namespace being switched to (NOT NULL) |
| 95 | * @name: the name of the profile to change to (NOT NULL) |
| 96 | * @request: requested perms |
| 97 | * @start: state to start matching in |
| 98 | * |
| 99 | * Returns: permission set |
| 100 | */ |
| 101 | static struct file_perms change_profile_perms(struct aa_profile *profile, |
| 102 | struct aa_namespace *ns, |
| 103 | const char *name, u32 request, |
| 104 | unsigned int start) |
| 105 | { |
| 106 | struct file_perms perms; |
| 107 | struct path_cond cond = { }; |
| 108 | unsigned int state; |
| 109 | |
| 110 | if (unconfined(profile)) { |
| 111 | perms.allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC; |
| 112 | perms.audit = perms.quiet = perms.kill = 0; |
| 113 | return perms; |
| 114 | } else if (!profile->file.dfa) { |
| 115 | return nullperms; |
| 116 | } else if ((ns == profile->ns)) { |
| 117 | /* try matching against rules with out namespace prepended */ |
| 118 | aa_str_perms(profile->file.dfa, start, name, &cond, &perms); |
| 119 | if (COMBINED_PERM_MASK(perms) & request) |
| 120 | return perms; |
| 121 | } |
| 122 | |
| 123 | /* try matching with namespace name and then profile */ |
| 124 | state = aa_dfa_match(profile->file.dfa, start, ns->base.name); |
| 125 | state = aa_dfa_match_len(profile->file.dfa, state, ":", 1); |
| 126 | aa_str_perms(profile->file.dfa, state, name, &cond, &perms); |
| 127 | |
| 128 | return perms; |
| 129 | } |
| 130 | |
| 131 | /** |
| 132 | * __attach_match_ - find an attachment match |
| 133 | * @name - to match against (NOT NULL) |
| 134 | * @head - profile list to walk (NOT NULL) |
| 135 | * |
| 136 | * Do a linear search on the profiles in the list. There is a matching |
| 137 | * preference where an exact match is preferred over a name which uses |
| 138 | * expressions to match, and matching expressions with the greatest |
| 139 | * xmatch_len are preferred. |
| 140 | * |
| 141 | * Requires: @head not be shared or have appropriate locks held |
| 142 | * |
| 143 | * Returns: profile or NULL if no match found |
| 144 | */ |
| 145 | static struct aa_profile *__attach_match(const char *name, |
| 146 | struct list_head *head) |
| 147 | { |
| 148 | int len = 0; |
| 149 | struct aa_profile *profile, *candidate = NULL; |
| 150 | |
| 151 | list_for_each_entry(profile, head, base.list) { |
| 152 | if (profile->flags & PFLAG_NULL) |
| 153 | continue; |
| 154 | if (profile->xmatch && profile->xmatch_len > len) { |
| 155 | unsigned int state = aa_dfa_match(profile->xmatch, |
| 156 | DFA_START, name); |
| 157 | u32 perm = dfa_user_allow(profile->xmatch, state); |
| 158 | /* any accepting state means a valid match. */ |
| 159 | if (perm & MAY_EXEC) { |
| 160 | candidate = profile; |
| 161 | len = profile->xmatch_len; |
| 162 | } |
| 163 | } else if (!strcmp(profile->base.name, name)) |
| 164 | /* exact non-re match, no more searching required */ |
| 165 | return profile; |
| 166 | } |
| 167 | |
| 168 | return candidate; |
| 169 | } |
| 170 | |
| 171 | /** |
| 172 | * find_attach - do attachment search for unconfined processes |
| 173 | * @ns: the current namespace (NOT NULL) |
| 174 | * @list: list to search (NOT NULL) |
| 175 | * @name: the executable name to match against (NOT NULL) |
| 176 | * |
| 177 | * Returns: profile or NULL if no match found |
| 178 | */ |
| 179 | static struct aa_profile *find_attach(struct aa_namespace *ns, |
| 180 | struct list_head *list, const char *name) |
| 181 | { |
| 182 | struct aa_profile *profile; |
| 183 | |
| 184 | read_lock(&ns->lock); |
| 185 | profile = aa_get_profile(__attach_match(name, list)); |
| 186 | read_unlock(&ns->lock); |
| 187 | |
| 188 | return profile; |
| 189 | } |
| 190 | |
| 191 | /** |
| 192 | * separate_fqname - separate the namespace and profile names |
| 193 | * @fqname: the fqname name to split (NOT NULL) |
| 194 | * @ns_name: the namespace name if it exists (NOT NULL) |
| 195 | * |
| 196 | * This is the xtable equivalent routine of aa_split_fqname. It finds the |
| 197 | * split in an xtable fqname which contains an embedded \0 instead of a : |
| 198 | * if a namespace is specified. This is done so the xtable is constant and |
| 199 | * isn't re-split on every lookup. |
| 200 | * |
| 201 | * Either the profile or namespace name may be optional but if the namespace |
| 202 | * is specified the profile name termination must be present. This results |
| 203 | * in the following possible encodings: |
| 204 | * profile_name\0 |
| 205 | * :ns_name\0profile_name\0 |
| 206 | * :ns_name\0\0 |
| 207 | * |
| 208 | * NOTE: the xtable fqname is pre-validated at load time in unpack_trans_table |
| 209 | * |
| 210 | * Returns: profile name if it is specified else NULL |
| 211 | */ |
| 212 | static const char *separate_fqname(const char *fqname, const char **ns_name) |
| 213 | { |
| 214 | const char *name; |
| 215 | |
| 216 | if (fqname[0] == ':') { |
| 217 | /* In this case there is guaranteed to be two \0 terminators |
| 218 | * in the string. They are verified at load time by |
| 219 | * by unpack_trans_table |
| 220 | */ |
| 221 | *ns_name = fqname + 1; /* skip : */ |
| 222 | name = *ns_name + strlen(*ns_name) + 1; |
| 223 | if (!*name) |
| 224 | name = NULL; |
| 225 | } else { |
| 226 | *ns_name = NULL; |
| 227 | name = fqname; |
| 228 | } |
| 229 | |
| 230 | return name; |
| 231 | } |
| 232 | |
| 233 | static const char *next_name(int xtype, const char *name) |
| 234 | { |
| 235 | return NULL; |
| 236 | } |
| 237 | |
| 238 | /** |
| 239 | * x_table_lookup - lookup an x transition name via transition table |
| 240 | * @profile: current profile (NOT NULL) |
| 241 | * @xindex: index into x transition table |
| 242 | * |
| 243 | * Returns: refcounted profile, or NULL on failure (MAYBE NULL) |
| 244 | */ |
| 245 | static struct aa_profile *x_table_lookup(struct aa_profile *profile, u32 xindex) |
| 246 | { |
| 247 | struct aa_profile *new_profile = NULL; |
| 248 | struct aa_namespace *ns = profile->ns; |
| 249 | u32 xtype = xindex & AA_X_TYPE_MASK; |
| 250 | int index = xindex & AA_X_INDEX_MASK; |
| 251 | const char *name; |
| 252 | |
| 253 | /* index is guaranteed to be in range, validated at load time */ |
| 254 | for (name = profile->file.trans.table[index]; !new_profile && name; |
| 255 | name = next_name(xtype, name)) { |
| 256 | struct aa_namespace *new_ns; |
| 257 | const char *xname = NULL; |
| 258 | |
| 259 | new_ns = NULL; |
| 260 | if (xindex & AA_X_CHILD) { |
| 261 | /* release by caller */ |
| 262 | new_profile = aa_find_child(profile, name); |
| 263 | continue; |
| 264 | } else if (*name == ':') { |
| 265 | /* switching namespace */ |
| 266 | const char *ns_name; |
| 267 | xname = name = separate_fqname(name, &ns_name); |
| 268 | if (!xname) |
| 269 | /* no name so use profile name */ |
| 270 | xname = profile->base.hname; |
| 271 | if (*ns_name == '@') { |
| 272 | /* TODO: variable support */ |
| 273 | ; |
| 274 | } |
| 275 | /* released below */ |
| 276 | new_ns = aa_find_namespace(ns, ns_name); |
| 277 | if (!new_ns) |
| 278 | continue; |
| 279 | } else if (*name == '@') { |
| 280 | /* TODO: variable support */ |
| 281 | continue; |
| 282 | } else { |
| 283 | /* basic namespace lookup */ |
| 284 | xname = name; |
| 285 | } |
| 286 | |
| 287 | /* released by caller */ |
| 288 | new_profile = aa_lookup_profile(new_ns ? new_ns : ns, xname); |
| 289 | aa_put_namespace(new_ns); |
| 290 | } |
| 291 | |
| 292 | /* released by caller */ |
| 293 | return new_profile; |
| 294 | } |
| 295 | |
| 296 | /** |
| 297 | * x_to_profile - get target profile for a given xindex |
| 298 | * @profile: current profile (NOT NULL) |
| 299 | * @name: name to lookup (NOT NULL) |
| 300 | * @xindex: index into x transition table |
| 301 | * |
| 302 | * find profile for a transition index |
| 303 | * |
| 304 | * Returns: refcounted profile or NULL if not found available |
| 305 | */ |
| 306 | static struct aa_profile *x_to_profile(struct aa_profile *profile, |
| 307 | const char *name, u32 xindex) |
| 308 | { |
| 309 | struct aa_profile *new_profile = NULL; |
| 310 | struct aa_namespace *ns = profile->ns; |
| 311 | u32 xtype = xindex & AA_X_TYPE_MASK; |
| 312 | |
| 313 | switch (xtype) { |
| 314 | case AA_X_NONE: |
| 315 | /* fail exec unless ix || ux fallback - handled by caller */ |
| 316 | return NULL; |
| 317 | case AA_X_NAME: |
| 318 | if (xindex & AA_X_CHILD) |
| 319 | /* released by caller */ |
| 320 | new_profile = find_attach(ns, &profile->base.profiles, |
| 321 | name); |
| 322 | else |
| 323 | /* released by caller */ |
| 324 | new_profile = find_attach(ns, &ns->base.profiles, |
| 325 | name); |
| 326 | break; |
| 327 | case AA_X_TABLE: |
| 328 | /* released by caller */ |
| 329 | new_profile = x_table_lookup(profile, xindex); |
| 330 | break; |
| 331 | } |
| 332 | |
| 333 | /* released by caller */ |
| 334 | return new_profile; |
| 335 | } |
| 336 | |
| 337 | /** |
| 338 | * apparmor_bprm_set_creds - set the new creds on the bprm struct |
| 339 | * @bprm: binprm for the exec (NOT NULL) |
| 340 | * |
| 341 | * Returns: %0 or error on failure |
| 342 | */ |
| 343 | int apparmor_bprm_set_creds(struct linux_binprm *bprm) |
| 344 | { |
| 345 | struct aa_task_cxt *cxt; |
| 346 | struct aa_profile *profile, *new_profile = NULL; |
| 347 | struct aa_namespace *ns; |
| 348 | char *buffer = NULL; |
| 349 | unsigned int state; |
| 350 | struct file_perms perms = {}; |
| 351 | struct path_cond cond = { |
| 352 | bprm->file->f_path.dentry->d_inode->i_uid, |
| 353 | bprm->file->f_path.dentry->d_inode->i_mode |
| 354 | }; |
| 355 | const char *name = NULL, *target = NULL, *info = NULL; |
| 356 | int error = cap_bprm_set_creds(bprm); |
| 357 | if (error) |
| 358 | return error; |
| 359 | |
| 360 | if (bprm->cred_prepared) |
| 361 | return 0; |
| 362 | |
| 363 | cxt = bprm->cred->security; |
| 364 | BUG_ON(!cxt); |
| 365 | |
| 366 | profile = aa_get_profile(aa_newest_version(cxt->profile)); |
| 367 | /* |
| 368 | * get the namespace from the replacement profile as replacement |
| 369 | * can change the namespace |
| 370 | */ |
| 371 | ns = profile->ns; |
| 372 | state = profile->file.start; |
| 373 | |
| 374 | /* buffer freed below, name is pointer into buffer */ |
| 375 | error = aa_get_name(&bprm->file->f_path, profile->path_flags, &buffer, |
| 376 | &name); |
| 377 | if (error) { |
| 378 | if (profile->flags & |
| 379 | (PFLAG_IX_ON_NAME_ERROR | PFLAG_UNCONFINED)) |
| 380 | error = 0; |
| 381 | info = "Exec failed name resolution"; |
| 382 | name = bprm->filename; |
| 383 | goto audit; |
| 384 | } |
| 385 | |
| 386 | /* Test for onexec first as onexec directives override other |
| 387 | * x transitions. |
| 388 | */ |
| 389 | if (unconfined(profile)) { |
| 390 | /* unconfined task */ |
| 391 | if (cxt->onexec) |
| 392 | /* change_profile on exec already been granted */ |
| 393 | new_profile = aa_get_profile(cxt->onexec); |
| 394 | else |
| 395 | new_profile = find_attach(ns, &ns->base.profiles, name); |
| 396 | if (!new_profile) |
| 397 | goto cleanup; |
| 398 | goto apply; |
| 399 | } |
| 400 | |
| 401 | /* find exec permissions for name */ |
| 402 | state = aa_str_perms(profile->file.dfa, state, name, &cond, &perms); |
| 403 | if (cxt->onexec) { |
| 404 | struct file_perms cp; |
| 405 | info = "change_profile onexec"; |
| 406 | if (!(perms.allow & AA_MAY_ONEXEC)) |
| 407 | goto audit; |
| 408 | |
| 409 | /* test if this exec can be paired with change_profile onexec. |
| 410 | * onexec permission is linked to exec with a standard pairing |
| 411 | * exec\0change_profile |
| 412 | */ |
| 413 | state = aa_dfa_null_transition(profile->file.dfa, state); |
| 414 | cp = change_profile_perms(profile, cxt->onexec->ns, name, |
| 415 | AA_MAY_ONEXEC, state); |
| 416 | |
| 417 | if (!(cp.allow & AA_MAY_ONEXEC)) |
| 418 | goto audit; |
| 419 | new_profile = aa_get_profile(aa_newest_version(cxt->onexec)); |
| 420 | goto apply; |
| 421 | } |
| 422 | |
| 423 | if (perms.allow & MAY_EXEC) { |
| 424 | /* exec permission determine how to transition */ |
| 425 | new_profile = x_to_profile(profile, name, perms.xindex); |
| 426 | if (!new_profile) { |
| 427 | if (perms.xindex & AA_X_INHERIT) { |
| 428 | /* (p|c|n)ix - don't change profile but do |
| 429 | * use the newest version, which was picked |
| 430 | * up above when getting profile |
| 431 | */ |
| 432 | info = "ix fallback"; |
| 433 | new_profile = aa_get_profile(profile); |
| 434 | goto x_clear; |
| 435 | } else if (perms.xindex & AA_X_UNCONFINED) { |
| 436 | new_profile = aa_get_profile(ns->unconfined); |
| 437 | info = "ux fallback"; |
| 438 | } else { |
| 439 | error = -ENOENT; |
| 440 | info = "profile not found"; |
| 441 | } |
| 442 | } |
| 443 | } else if (COMPLAIN_MODE(profile)) { |
| 444 | /* no exec permission - are we in learning mode */ |
| 445 | new_profile = aa_new_null_profile(profile, 0); |
| 446 | if (!new_profile) { |
| 447 | error = -ENOMEM; |
| 448 | info = "could not create null profile"; |
| 449 | } else { |
| 450 | error = -EACCES; |
| 451 | target = new_profile->base.hname; |
| 452 | } |
| 453 | perms.xindex |= AA_X_UNSAFE; |
| 454 | } else |
| 455 | /* fail exec */ |
| 456 | error = -EACCES; |
| 457 | |
| 458 | if (!new_profile) |
| 459 | goto audit; |
| 460 | |
| 461 | if (bprm->unsafe & LSM_UNSAFE_SHARE) { |
| 462 | /* FIXME: currently don't mediate shared state */ |
| 463 | ; |
| 464 | } |
| 465 | |
| 466 | if (bprm->unsafe & (LSM_UNSAFE_PTRACE | LSM_UNSAFE_PTRACE_CAP)) { |
| 467 | error = may_change_ptraced_domain(current, new_profile); |
| 468 | if (error) { |
| 469 | aa_put_profile(new_profile); |
| 470 | goto audit; |
| 471 | } |
| 472 | } |
| 473 | |
| 474 | /* Determine if secure exec is needed. |
| 475 | * Can be at this point for the following reasons: |
| 476 | * 1. unconfined switching to confined |
| 477 | * 2. confined switching to different confinement |
| 478 | * 3. confined switching to unconfined |
| 479 | * |
| 480 | * Cases 2 and 3 are marked as requiring secure exec |
| 481 | * (unless policy specified "unsafe exec") |
| 482 | * |
| 483 | * bprm->unsafe is used to cache the AA_X_UNSAFE permission |
| 484 | * to avoid having to recompute in secureexec |
| 485 | */ |
| 486 | if (!(perms.xindex & AA_X_UNSAFE)) { |
| 487 | AA_DEBUG("scrubbing environment variables for %s profile=%s\n", |
| 488 | name, new_profile->base.hname); |
| 489 | bprm->unsafe |= AA_SECURE_X_NEEDED; |
| 490 | } |
| 491 | apply: |
| 492 | target = new_profile->base.hname; |
| 493 | /* when transitioning profiles clear unsafe personality bits */ |
| 494 | bprm->per_clear |= PER_CLEAR_ON_SETID; |
| 495 | |
| 496 | x_clear: |
| 497 | aa_put_profile(cxt->profile); |
| 498 | /* transfer new profile reference will be released when cxt is freed */ |
| 499 | cxt->profile = new_profile; |
| 500 | |
| 501 | /* clear out all temporary/transitional state from the context */ |
| 502 | aa_put_profile(cxt->previous); |
| 503 | aa_put_profile(cxt->onexec); |
| 504 | cxt->previous = NULL; |
| 505 | cxt->onexec = NULL; |
| 506 | cxt->token = 0; |
| 507 | |
| 508 | audit: |
| 509 | error = aa_audit_file(profile, &perms, GFP_KERNEL, OP_EXEC, MAY_EXEC, |
| 510 | name, target, cond.uid, info, error); |
| 511 | |
| 512 | cleanup: |
| 513 | aa_put_profile(profile); |
| 514 | kfree(buffer); |
| 515 | |
| 516 | return error; |
| 517 | } |
| 518 | |
| 519 | /** |
| 520 | * apparmor_bprm_secureexec - determine if secureexec is needed |
| 521 | * @bprm: binprm for exec (NOT NULL) |
| 522 | * |
| 523 | * Returns: %1 if secureexec is needed else %0 |
| 524 | */ |
| 525 | int apparmor_bprm_secureexec(struct linux_binprm *bprm) |
| 526 | { |
| 527 | int ret = cap_bprm_secureexec(bprm); |
| 528 | |
| 529 | /* the decision to use secure exec is computed in set_creds |
| 530 | * and stored in bprm->unsafe. |
| 531 | */ |
| 532 | if (!ret && (bprm->unsafe & AA_SECURE_X_NEEDED)) |
| 533 | ret = 1; |
| 534 | |
| 535 | return ret; |
| 536 | } |
| 537 | |
| 538 | /** |
| 539 | * apparmor_bprm_committing_creds - do task cleanup on committing new creds |
| 540 | * @bprm: binprm for the exec (NOT NULL) |
| 541 | */ |
| 542 | void apparmor_bprm_committing_creds(struct linux_binprm *bprm) |
| 543 | { |
| 544 | struct aa_profile *profile = __aa_current_profile(); |
| 545 | struct aa_task_cxt *new_cxt = bprm->cred->security; |
| 546 | |
| 547 | /* bail out if unconfined or not changing profile */ |
| 548 | if ((new_cxt->profile == profile) || |
| 549 | (unconfined(new_cxt->profile))) |
| 550 | return; |
| 551 | |
| 552 | current->pdeath_signal = 0; |
| 553 | |
| 554 | /* reset soft limits and set hard limits for the new profile */ |
| 555 | __aa_transition_rlimits(profile, new_cxt->profile); |
| 556 | } |
| 557 | |
| 558 | /** |
| 559 | * apparmor_bprm_commited_cred - do cleanup after new creds committed |
| 560 | * @bprm: binprm for the exec (NOT NULL) |
| 561 | */ |
| 562 | void apparmor_bprm_committed_creds(struct linux_binprm *bprm) |
| 563 | { |
| 564 | /* TODO: cleanup signals - ipc mediation */ |
| 565 | return; |
| 566 | } |
| 567 | |
| 568 | /* |
| 569 | * Functions for self directed profile change |
| 570 | */ |
| 571 | |
| 572 | /** |
| 573 | * new_compound_name - create an hname with @n2 appended to @n1 |
| 574 | * @n1: base of hname (NOT NULL) |
| 575 | * @n2: name to append (NOT NULL) |
| 576 | * |
| 577 | * Returns: new name or NULL on error |
| 578 | */ |
| 579 | static char *new_compound_name(const char *n1, const char *n2) |
| 580 | { |
| 581 | char *name = kmalloc(strlen(n1) + strlen(n2) + 3, GFP_KERNEL); |
| 582 | if (name) |
| 583 | sprintf(name, "%s//%s", n1, n2); |
| 584 | return name; |
| 585 | } |
| 586 | |
| 587 | /** |
| 588 | * aa_change_hat - change hat to/from subprofile |
| 589 | * @hats: vector of hat names to try changing into (MAYBE NULL if @count == 0) |
| 590 | * @count: number of hat names in @hats |
| 591 | * @token: magic value to validate the hat change |
| 592 | * @permtest: true if this is just a permission test |
| 593 | * |
| 594 | * Change to the first profile specified in @hats that exists, and store |
| 595 | * the @hat_magic in the current task context. If the count == 0 and the |
| 596 | * @token matches that stored in the current task context, return to the |
| 597 | * top level profile. |
| 598 | * |
| 599 | * Returns %0 on success, error otherwise. |
| 600 | */ |
| 601 | int aa_change_hat(const char *hats[], int count, u64 token, bool permtest) |
| 602 | { |
| 603 | const struct cred *cred; |
| 604 | struct aa_task_cxt *cxt; |
| 605 | struct aa_profile *profile, *previous_profile, *hat = NULL; |
| 606 | char *name = NULL; |
| 607 | int i; |
| 608 | struct file_perms perms = {}; |
| 609 | const char *target = NULL, *info = NULL; |
| 610 | int error = 0; |
| 611 | |
| 612 | /* released below */ |
| 613 | cred = get_current_cred(); |
| 614 | cxt = cred->security; |
| 615 | profile = aa_cred_profile(cred); |
| 616 | previous_profile = cxt->previous; |
| 617 | |
| 618 | if (unconfined(profile)) { |
| 619 | info = "unconfined"; |
| 620 | error = -EPERM; |
| 621 | goto audit; |
| 622 | } |
| 623 | |
| 624 | if (count) { |
| 625 | /* attempting to change into a new hat or switch to a sibling */ |
| 626 | struct aa_profile *root; |
| 627 | root = PROFILE_IS_HAT(profile) ? profile->parent : profile; |
| 628 | |
| 629 | /* find first matching hat */ |
| 630 | for (i = 0; i < count && !hat; i++) |
| 631 | /* released below */ |
| 632 | hat = aa_find_child(root, hats[i]); |
| 633 | if (!hat) { |
| 634 | if (!COMPLAIN_MODE(root) || permtest) { |
| 635 | if (list_empty(&root->base.profiles)) |
| 636 | error = -ECHILD; |
| 637 | else |
| 638 | error = -ENOENT; |
| 639 | goto out; |
| 640 | } |
| 641 | |
| 642 | /* |
| 643 | * In complain mode and failed to match any hats. |
| 644 | * Audit the failure is based off of the first hat |
| 645 | * supplied. This is done due how userspace |
| 646 | * interacts with change_hat. |
| 647 | * |
| 648 | * TODO: Add logging of all failed hats |
| 649 | */ |
| 650 | |
| 651 | /* freed below */ |
| 652 | name = new_compound_name(root->base.hname, hats[0]); |
| 653 | target = name; |
| 654 | /* released below */ |
| 655 | hat = aa_new_null_profile(profile, 1); |
| 656 | if (!hat) { |
| 657 | info = "failed null profile create"; |
| 658 | error = -ENOMEM; |
| 659 | goto audit; |
| 660 | } |
| 661 | } else { |
| 662 | target = hat->base.hname; |
| 663 | if (!PROFILE_IS_HAT(hat)) { |
| 664 | info = "target not hat"; |
| 665 | error = -EPERM; |
| 666 | goto audit; |
| 667 | } |
| 668 | } |
| 669 | |
| 670 | error = may_change_ptraced_domain(current, hat); |
| 671 | if (error) { |
| 672 | info = "ptraced"; |
| 673 | error = -EPERM; |
| 674 | goto audit; |
| 675 | } |
| 676 | |
| 677 | if (!permtest) { |
| 678 | error = aa_set_current_hat(hat, token); |
| 679 | if (error == -EACCES) |
| 680 | /* kill task in case of brute force attacks */ |
| 681 | perms.kill = AA_MAY_CHANGEHAT; |
| 682 | else if (name && !error) |
| 683 | /* reset error for learning of new hats */ |
| 684 | error = -ENOENT; |
| 685 | } |
| 686 | } else if (previous_profile) { |
| 687 | /* Return to saved profile. Kill task if restore fails |
| 688 | * to avoid brute force attacks |
| 689 | */ |
| 690 | target = previous_profile->base.hname; |
| 691 | error = aa_restore_previous_profile(token); |
| 692 | perms.kill = AA_MAY_CHANGEHAT; |
| 693 | } else |
| 694 | /* ignore restores when there is no saved profile */ |
| 695 | goto out; |
| 696 | |
| 697 | audit: |
| 698 | if (!permtest) |
| 699 | error = aa_audit_file(profile, &perms, GFP_KERNEL, |
| 700 | OP_CHANGE_HAT, AA_MAY_CHANGEHAT, NULL, |
| 701 | target, 0, info, error); |
| 702 | |
| 703 | out: |
| 704 | aa_put_profile(hat); |
| 705 | kfree(name); |
| 706 | put_cred(cred); |
| 707 | |
| 708 | return error; |
| 709 | } |
| 710 | |
| 711 | /** |
| 712 | * aa_change_profile - perform a one-way profile transition |
| 713 | * @ns_name: name of the profile namespace to change to (MAYBE NULL) |
| 714 | * @hname: name of profile to change to (MAYBE NULL) |
| 715 | * @onexec: whether this transition is to take place immediately or at exec |
| 716 | * @permtest: true if this is just a permission test |
| 717 | * |
| 718 | * Change to new profile @name. Unlike with hats, there is no way |
| 719 | * to change back. If @name isn't specified the current profile name is |
| 720 | * used. |
| 721 | * If @onexec then the transition is delayed until |
| 722 | * the next exec. |
| 723 | * |
| 724 | * Returns %0 on success, error otherwise. |
| 725 | */ |
| 726 | int aa_change_profile(const char *ns_name, const char *hname, bool onexec, |
| 727 | bool permtest) |
| 728 | { |
| 729 | const struct cred *cred; |
| 730 | struct aa_task_cxt *cxt; |
| 731 | struct aa_profile *profile, *target = NULL; |
| 732 | struct aa_namespace *ns = NULL; |
| 733 | struct file_perms perms = {}; |
| 734 | const char *name = NULL, *info = NULL; |
| 735 | int op, error = 0; |
| 736 | u32 request; |
| 737 | |
| 738 | if (!hname && !ns_name) |
| 739 | return -EINVAL; |
| 740 | |
| 741 | if (onexec) { |
| 742 | request = AA_MAY_ONEXEC; |
| 743 | op = OP_CHANGE_ONEXEC; |
| 744 | } else { |
| 745 | request = AA_MAY_CHANGE_PROFILE; |
| 746 | op = OP_CHANGE_PROFILE; |
| 747 | } |
| 748 | |
| 749 | cred = get_current_cred(); |
| 750 | cxt = cred->security; |
| 751 | profile = aa_cred_profile(cred); |
| 752 | |
| 753 | if (ns_name) { |
| 754 | /* released below */ |
| 755 | ns = aa_find_namespace(profile->ns, ns_name); |
| 756 | if (!ns) { |
| 757 | /* we don't create new namespace in complain mode */ |
| 758 | name = ns_name; |
| 759 | info = "namespace not found"; |
| 760 | error = -ENOENT; |
| 761 | goto audit; |
| 762 | } |
| 763 | } else |
| 764 | /* released below */ |
| 765 | ns = aa_get_namespace(profile->ns); |
| 766 | |
| 767 | /* if the name was not specified, use the name of the current profile */ |
| 768 | if (!hname) { |
| 769 | if (unconfined(profile)) |
| 770 | hname = ns->unconfined->base.hname; |
| 771 | else |
| 772 | hname = profile->base.hname; |
| 773 | } |
| 774 | |
| 775 | perms = change_profile_perms(profile, ns, hname, request, |
| 776 | profile->file.start); |
| 777 | if (!(perms.allow & request)) { |
| 778 | error = -EACCES; |
| 779 | goto audit; |
| 780 | } |
| 781 | |
| 782 | /* released below */ |
| 783 | target = aa_lookup_profile(ns, hname); |
| 784 | if (!target) { |
| 785 | info = "profile not found"; |
| 786 | error = -ENOENT; |
| 787 | if (permtest || !COMPLAIN_MODE(profile)) |
| 788 | goto audit; |
| 789 | /* released below */ |
| 790 | target = aa_new_null_profile(profile, 0); |
| 791 | if (!target) { |
| 792 | info = "failed null profile create"; |
| 793 | error = -ENOMEM; |
| 794 | goto audit; |
| 795 | } |
| 796 | } |
| 797 | |
| 798 | /* check if tracing task is allowed to trace target domain */ |
| 799 | error = may_change_ptraced_domain(current, target); |
| 800 | if (error) { |
| 801 | info = "ptrace prevents transition"; |
| 802 | goto audit; |
| 803 | } |
| 804 | |
| 805 | if (permtest) |
| 806 | goto audit; |
| 807 | |
| 808 | if (onexec) |
| 809 | error = aa_set_current_onexec(target); |
| 810 | else |
| 811 | error = aa_replace_current_profile(target); |
| 812 | |
| 813 | audit: |
| 814 | if (!permtest) |
| 815 | error = aa_audit_file(profile, &perms, GFP_KERNEL, op, request, |
| 816 | name, hname, 0, info, error); |
| 817 | |
| 818 | aa_put_namespace(ns); |
| 819 | aa_put_profile(target); |
| 820 | put_cred(cred); |
| 821 | |
| 822 | return error; |
| 823 | } |