security/apparmor/domain.c

   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 #include "include/policy_ns.h"
  33
  34 /**
  35  * aa_free_domain_entries - free entries in a domain table
  36  * @domain: the domain table to free  (MAYBE NULL)
  37  */
  38 void aa_free_domain_entries(struct aa_domain *domain)
  39 {
  40         int i;
  41         if (domain) {
  42                 if (!domain->table)
  43                         return;
  44
  45                 for (i = 0; i < domain->size; i++)
  46                         kzfree(domain->table[i]);
  47                 kzfree(domain->table);
  48                 domain->table = NULL;
  49         }
  50 }
  51
  52 /**
  53  * may_change_ptraced_domain - check if can change profile on ptraced task
  54  * @to_label: profile to change to  (NOT NULL)
  55  * @info: message if there is an error
  56  *
  57  * Check if current is ptraced and if so if the tracing task is allowed
  58  * to trace the new domain
  59  *
  60  * Returns: %0 or error if change not allowed
  61  */
  62 static int may_change_ptraced_domain(struct aa_label *to_label,
  63                                      const char **info)
  64 {
  65         struct task_struct *tracer;
  66         struct aa_label *tracerl = NULL;
  67         int error = 0;
  68
  69         rcu_read_lock();
  70         tracer = ptrace_parent(current);
  71         if (tracer)
  72                 /* released below */
  73                 tracerl = aa_get_task_label(tracer);
  74
  75         /* not ptraced */
  76         if (!tracer || unconfined(tracerl))
  77                 goto out;
  78
  79         error = aa_may_ptrace(tracerl, to_label, PTRACE_MODE_ATTACH);
  80
  81 out:
  82         rcu_read_unlock();
  83         aa_put_label(tracerl);
  84
  85         if (error)
  86                 *info = "ptrace prevents transition";
  87         return error;
  88 }
  89
  90 /**** TODO: dedup to aa_label_match - needs perm and dfa, merging
  91  * specifically this is an exact copy of aa_label_match except
  92  * aa_compute_perms is replaced with aa_compute_fperms
  93  * and policy.dfa with file.dfa
  94  ****/
  95 /* match a profile and its associated ns component if needed
  96  * Assumes visibility test has already been done.
  97  * If a subns profile is not to be matched should be prescreened with
  98  * visibility test.
  99  */
 100 static inline unsigned int match_component(struct aa_profile *profile,
 101                                            struct aa_profile *tp,
 102                                            bool stack, unsigned int state)
 103 {
 104         const char *ns_name;
 105
 106         if (stack)
 107                 state = aa_dfa_match(profile->file.dfa, state, "&");
 108         if (profile->ns == tp->ns)
 109                 return aa_dfa_match(profile->file.dfa, state, tp->base.hname);
 110
 111         /* try matching with namespace name and then profile */
 112         ns_name = aa_ns_name(profile->ns, tp->ns, true);
 113         state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
 114         state = aa_dfa_match(profile->file.dfa, state, ns_name);
 115         state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
 116         return aa_dfa_match(profile->file.dfa, state, tp->base.hname);
 117 }
 118
 119 /**
 120  * label_compound_match - find perms for full compound label
 121  * @profile: profile to find perms for
 122  * @label: label to check access permissions for
 123  * @stack: whether this is a stacking request
 124  * @start: state to start match in
 125  * @subns: whether to do permission checks on components in a subns
 126  * @request: permissions to request
 127  * @perms: perms struct to set
 128  *
 129  * Returns: 0 on success else ERROR
 130  *
 131  * For the label A//&B//&C this does the perm match for A//&B//&C
 132  * @perms should be preinitialized with allperms OR a previous permission
 133  *        check to be stacked.
 134  */
 135 static int label_compound_match(struct aa_profile *profile,
 136                                 struct aa_label *label, bool stack,
 137                                 unsigned int state, bool subns, u32 request,
 138                                 struct aa_perms *perms)
 139 {
 140         struct aa_profile *tp;
 141         struct label_it i;
 142         struct path_cond cond = { };
 143
 144         /* find first subcomponent that is visible */
 145         label_for_each(i, label, tp) {
 146                 if (!aa_ns_visible(profile->ns, tp->ns, subns))
 147                         continue;
 148                 state = match_component(profile, tp, stack, state);
 149                 if (!state)
 150                         goto fail;
 151                 goto next;
 152         }
 153
 154         /* no component visible */
 155         *perms = allperms;
 156         return 0;
 157
 158 next:
 159         label_for_each_cont(i, label, tp) {
 160                 if (!aa_ns_visible(profile->ns, tp->ns, subns))
 161                         continue;
 162                 state = aa_dfa_match(profile->file.dfa, state, "//&");
 163                 state = match_component(profile, tp, false, state);
 164                 if (!state)
 165                         goto fail;
 166         }
 167         *perms = aa_compute_fperms(profile->file.dfa, state, &cond);
 168         aa_apply_modes_to_perms(profile, perms);
 169         if ((perms->allow & request) != request)
 170                 return -EACCES;
 171
 172         return 0;
 173
 174 fail:
 175         *perms = nullperms;
 176         return -EACCES;
 177 }
 178
 179 /**
 180  * label_components_match - find perms for all subcomponents of a label
 181  * @profile: profile to find perms for
 182  * @label: label to check access permissions for
 183  * @stack: whether this is a stacking request
 184  * @start: state to start match in
 185  * @subns: whether to do permission checks on components in a subns
 186  * @request: permissions to request
 187  * @perms: an initialized perms struct to add accumulation to
 188  *
 189  * Returns: 0 on success else ERROR
 190  *
 191  * For the label A//&B//&C this does the perm match for each of A and B and C
 192  * @perms should be preinitialized with allperms OR a previous permission
 193  *        check to be stacked.
 194  */
 195 static int label_components_match(struct aa_profile *profile,
 196                                   struct aa_label *label, bool stack,
 197                                   unsigned int start, bool subns, u32 request,
 198                                   struct aa_perms *perms)
 199 {
 200         struct aa_profile *tp;
 201         struct label_it i;
 202         struct aa_perms tmp;
 203         struct path_cond cond = { };
 204         unsigned int state = 0;
 205
 206         /* find first subcomponent to test */
 207         label_for_each(i, label, tp) {
 208                 if (!aa_ns_visible(profile->ns, tp->ns, subns))
 209                         continue;
 210                 state = match_component(profile, tp, stack, start);
 211                 if (!state)
 212                         goto fail;
 213                 goto next;
 214         }
 215
 216         /* no subcomponents visible - no change in perms */
 217         return 0;
 218
 219 next:
 220         tmp = aa_compute_fperms(profile->file.dfa, state, &cond);
 221         aa_apply_modes_to_perms(profile, &tmp);
 222         aa_perms_accum(perms, &tmp);
 223         label_for_each_cont(i, label, tp) {
 224                 if (!aa_ns_visible(profile->ns, tp->ns, subns))
 225                         continue;
 226                 state = match_component(profile, tp, stack, start);
 227                 if (!state)
 228                         goto fail;
 229                 tmp = aa_compute_fperms(profile->file.dfa, state, &cond);
 230                 aa_apply_modes_to_perms(profile, &tmp);
 231                 aa_perms_accum(perms, &tmp);
 232         }
 233
 234         if ((perms->allow & request) != request)
 235                 return -EACCES;
 236
 237         return 0;
 238
 239 fail:
 240         *perms = nullperms;
 241         return -EACCES;
 242 }
 243
 244 /**
 245  * label_match - do a multi-component label match
 246  * @profile: profile to match against (NOT NULL)
 247  * @label: label to match (NOT NULL)
 248  * @stack: whether this is a stacking request
 249  * @state: state to start in
 250  * @subns: whether to match subns components
 251  * @request: permission request
 252  * @perms: Returns computed perms (NOT NULL)
 253  *
 254  * Returns: the state the match finished in, may be the none matching state
 255  */
 256 static int label_match(struct aa_profile *profile, struct aa_label *label,
 257                        bool stack, unsigned int state, bool subns, u32 request,
 258                        struct aa_perms *perms)
 259 {
 260         int error;
 261
 262         *perms = nullperms;
 263         error = label_compound_match(profile, label, stack, state, subns,
 264                                      request, perms);
 265         if (!error)
 266                 return error;
 267
 268         *perms = allperms;
 269         return label_components_match(profile, label, stack, state, subns,
 270                                       request, perms);
 271 }
 272
 273 /******* end TODO: dedup *****/
 274
 275 /**
 276  * change_profile_perms - find permissions for change_profile
 277  * @profile: the current profile  (NOT NULL)
 278  * @target: label to transition to (NOT NULL)
 279  * @stack: whether this is a stacking request
 280  * @request: requested perms
 281  * @start: state to start matching in
 282  *
 283  *
 284  * Returns: permission set
 285  *
 286  * currently only matches full label A//&B//&C or individual components A, B, C
 287  * not arbitrary combinations. Eg. A//&B, C
 288  */
 289 static int change_profile_perms(struct aa_profile *profile,
 290                                 struct aa_label *target, bool stack,
 291                                 u32 request, unsigned int start,
 292                                 struct aa_perms *perms)
 293 {
 294         if (profile_unconfined(profile)) {
 295                 perms->allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC;
 296                 perms->audit = perms->quiet = perms->kill = 0;
 297                 return 0;
 298         }
 299
 300         /* TODO: add profile in ns screening */
 301         return label_match(profile, target, stack, start, true, request, perms);
 302 }
 303
 304 /**
 305  * __attach_match_ - find an attachment match
 306  * @name - to match against  (NOT NULL)
 307  * @head - profile list to walk  (NOT NULL)
 308  * @info - info message if there was an error (NOT NULL)
 309  *
 310  * Do a linear search on the profiles in the list.  There is a matching
 311  * preference where an exact match is preferred over a name which uses
 312  * expressions to match, and matching expressions with the greatest
 313  * xmatch_len are preferred.
 314  *
 315  * Requires: @head not be shared or have appropriate locks held
 316  *
 317  * Returns: profile or NULL if no match found
 318  */
 319 static struct aa_profile *__attach_match(const char *name,
 320                                          struct list_head *head,
 321                                          const char **info)
 322 {
 323         int len = 0;
 324         bool conflict = false;
 325         struct aa_profile *profile, *candidate = NULL;
 326
 327         list_for_each_entry_rcu(profile, head, base.list) {
 328                 if (profile->label.flags & FLAG_NULL &&
 329                     &profile->label == ns_unconfined(profile->ns))
 330                         continue;
 331
 332                 if (profile->xmatch) {
 333                         if (profile->xmatch_len >= len) {
 334                                 unsigned int state;
 335                                 u32 perm;
 336
 337                                 state = aa_dfa_match(profile->xmatch,
 338                                                      DFA_START, name);
 339                                 perm = dfa_user_allow(profile->xmatch, state);
 340                                 /* any accepting state means a valid match. */
 341                                 if (perm & MAY_EXEC) {
 342                                         if (profile->xmatch_len == len) {
 343                                                 conflict = true;
 344                                                 continue;
 345                                         }
 346                                         candidate = profile;
 347                                         len = profile->xmatch_len;
 348                                         conflict = false;
 349                                 }
 350                         }
 351                 } else if (!strcmp(profile->base.name, name))
 352                         /* exact non-re match, no more searching required */
 353                         return profile;
 354         }
 355
 356         if (conflict) {
 357                 *info = "conflicting profile attachments";
 358                 return NULL;
 359         }
 360
 361         return candidate;
 362 }
 363
 364 /**
 365  * find_attach - do attachment search for unconfined processes
 366  * @ns: the current namespace  (NOT NULL)
 367  * @list: list to search  (NOT NULL)
 368  * @name: the executable name to match against  (NOT NULL)
 369  * @info: info message if there was an error
 370  *
 371  * Returns: label or NULL if no match found
 372  */
 373 static struct aa_label *find_attach(struct aa_ns *ns, struct list_head *list,
 374                                     const char *name, const char **info)
 375 {
 376         struct aa_profile *profile;
 377
 378         rcu_read_lock();
 379         profile = aa_get_profile(__attach_match(name, list, info));
 380         rcu_read_unlock();
 381
 382         return profile ? &profile->label : NULL;
 383 }
 384
 385 static const char *next_name(int xtype, const char *name)
 386 {
 387         return NULL;
 388 }
 389
 390 /**
 391  * x_table_lookup - lookup an x transition name via transition table
 392  * @profile: current profile (NOT NULL)
 393  * @xindex: index into x transition table
 394  * @name: returns: name tested to find label (NOT NULL)
 395  *
 396  * Returns: refcounted label, or NULL on failure (MAYBE NULL)
 397  */
 398 struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
 399                                 const char **name)
 400 {
 401         struct aa_label *label = NULL;
 402         u32 xtype = xindex & AA_X_TYPE_MASK;
 403         int index = xindex & AA_X_INDEX_MASK;
 404
 405         AA_BUG(!name);
 406
 407         /* index is guaranteed to be in range, validated at load time */
 408         /* TODO: move lookup parsing to unpack time so this is a straight
 409          *       index into the resultant label
 410          */
 411         for (*name = profile->file.trans.table[index]; !label && *name;
 412              *name = next_name(xtype, *name)) {
 413                 if (xindex & AA_X_CHILD) {
 414                         struct aa_profile *new_profile;
 415                         /* release by caller */
 416                         new_profile = aa_find_child(profile, *name);
 417                         if (new_profile)
 418                                 label = &new_profile->label;
 419                         continue;
 420                 }
 421                 label = aa_label_parse(&profile->label, *name, GFP_ATOMIC,
 422                                        true, false);
 423                 if (IS_ERR(label))
 424                         label = NULL;
 425         }
 426
 427         /* released by caller */
 428
 429         return label;
 430 }
 431
 432 /**
 433  * x_to_label - get target label for a given xindex
 434  * @profile: current profile  (NOT NULL)
 435  * @name: name to lookup (NOT NULL)
 436  * @xindex: index into x transition table
 437  * @lookupname: returns: name used in lookup if one was specified (NOT NULL)
 438  *
 439  * find label for a transition index
 440  *
 441  * Returns: refcounted label or NULL if not found available
 442  */
 443 static struct aa_label *x_to_label(struct aa_profile *profile,
 444                                    const char *name, u32 xindex,
 445                                    const char **lookupname,
 446                                    const char **info)
 447 {
 448         struct aa_label *new = NULL;
 449         struct aa_ns *ns = profile->ns;
 450         u32 xtype = xindex & AA_X_TYPE_MASK;
 451         const char *stack = NULL;
 452
 453         switch (xtype) {
 454         case AA_X_NONE:
 455                 /* fail exec unless ix || ux fallback - handled by caller */
 456                 *lookupname = NULL;
 457                 break;
 458         case AA_X_TABLE:
 459                 /* TODO: fix when perm mapping done at unload */
 460                 stack = profile->file.trans.table[xindex & AA_X_INDEX_MASK];
 461                 if (*stack != '&') {
 462                         /* released by caller */
 463                         new = x_table_lookup(profile, xindex, lookupname);
 464                         stack = NULL;
 465                         break;
 466                 }
 467                 /* fall through to X_NAME */
 468         case AA_X_NAME:
 469                 if (xindex & AA_X_CHILD)
 470                         /* released by caller */
 471                         new = find_attach(ns, &profile->base.profiles,
 472                                           name, info);
 473                 else
 474                         /* released by caller */
 475                         new = find_attach(ns, &ns->base.profiles,
 476                                           name, info);
 477                 *lookupname = name;
 478                 break;
 479         }
 480
 481         if (!new) {
 482                 if (xindex & AA_X_INHERIT) {
 483                         /* (p|c|n)ix - don't change profile but do
 484                          * use the newest version
 485                          */
 486                         *info = "ix fallback";
 487                         /* no profile && no error */
 488                         new = aa_get_newest_label(&profile->label);
 489                 } else if (xindex & AA_X_UNCONFINED) {
 490                         new = aa_get_newest_label(ns_unconfined(profile->ns));
 491                         *info = "ux fallback";
 492                 }
 493         }
 494
 495         if (new && stack) {
 496                 /* base the stack on post domain transition */
 497                 struct aa_label *base = new;
 498
 499                 new = aa_label_parse(base, stack, GFP_ATOMIC, true, false);
 500                 if (IS_ERR(new))
 501                         new = NULL;
 502                 aa_put_label(base);
 503         }
 504
 505         /* released by caller */
 506         return new;
 507 }
 508
 509 static struct aa_label *profile_transition(struct aa_profile *profile,
 510                                            const struct linux_binprm *bprm,
 511                                            char *buffer, struct path_cond *cond,
 512                                            bool *secure_exec)
 513 {
 514         struct aa_label *new = NULL;
 515         const char *info = NULL, *name = NULL, *target = NULL;
 516         unsigned int state = profile->file.start;
 517         struct aa_perms perms = {};
 518         bool nonewprivs = false;
 519         int error = 0;
 520
 521         AA_BUG(!profile);
 522         AA_BUG(!bprm);
 523         AA_BUG(!buffer);
 524
 525         error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
 526                              &name, &info, profile->disconnected);
 527         if (error) {
 528                 if (profile_unconfined(profile) ||
 529                     (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
 530                         AA_DEBUG("name lookup ix on error");
 531                         error = 0;
 532                         new = aa_get_newest_label(&profile->label);
 533                 }
 534                 name = bprm->filename;
 535                 goto audit;
 536         }
 537
 538         if (profile_unconfined(profile)) {
 539                 new = find_attach(profile->ns, &profile->ns->base.profiles,
 540                                   name, &info);
 541                 if (new) {
 542                         AA_DEBUG("unconfined attached to new label");
 543                         return new;
 544                 }
 545                 AA_DEBUG("unconfined exec no attachment");
 546                 return aa_get_newest_label(&profile->label);
 547         }
 548
 549         /* find exec permissions for name */
 550         state = aa_str_perms(profile->file.dfa, state, name, cond, &perms);
 551         if (perms.allow & MAY_EXEC) {
 552                 /* exec permission determine how to transition */
 553                 new = x_to_label(profile, name, perms.xindex, &target, &info);
 554                 if (new && new->proxy == profile->label.proxy && info) {
 555                         /* hack ix fallback - improve how this is detected */
 556                         goto audit;
 557                 } else if (!new) {
 558                         error = -EACCES;
 559                         info = "profile transition not found";
 560                         /* remove MAY_EXEC to audit as failure */
 561                         perms.allow &= ~MAY_EXEC;
 562                 }
 563         } else if (COMPLAIN_MODE(profile)) {
 564                 /* no exec permission - learning mode */
 565                 struct aa_profile *new_profile = NULL;
 566                 char *n = kstrdup(name, GFP_ATOMIC);
 567
 568                 if (n) {
 569                         /* name is ptr into buffer */
 570                         long pos = name - buffer;
 571                         /* break per cpu buffer hold */
 572                         put_buffers(buffer);
 573                         new_profile = aa_new_null_profile(profile, false, n,
 574                                                           GFP_KERNEL);
 575                         get_buffers(buffer);
 576                         name = buffer + pos;
 577                         strcpy((char *)name, n);
 578                         kfree(n);
 579                 }
 580                 if (!new_profile) {
 581                         error = -ENOMEM;
 582                         info = "could not create null profile";
 583                 } else {
 584                         error = -EACCES;
 585                         new = &new_profile->label;
 586                 }
 587                 perms.xindex |= AA_X_UNSAFE;
 588         } else
 589                 /* fail exec */
 590                 error = -EACCES;
 591
 592         if (!new)
 593                 goto audit;
 594
 595
 596         if (!(perms.xindex & AA_X_UNSAFE)) {
 597                 if (DEBUG_ON) {
 598                         dbg_printk("apparmor: scrubbing environment variables"
 599                                    " for %s profile=", name);
 600                         aa_label_printk(new, GFP_ATOMIC);
 601                         dbg_printk("\n");
 602                 }
 603                 *secure_exec = true;
 604         }
 605
 606 audit:
 607         aa_audit_file(profile, &perms, OP_EXEC, MAY_EXEC, name, target, new,
 608                       cond->uid, info, error);
 609         if (!new || nonewprivs) {
 610                 aa_put_label(new);
 611                 return ERR_PTR(error);
 612         }
 613
 614         return new;
 615 }
 616
 617 static int profile_onexec(struct aa_profile *profile, struct aa_label *onexec,
 618                           bool stack, const struct linux_binprm *bprm,
 619                           char *buffer, struct path_cond *cond,
 620                           bool *secure_exec)
 621 {
 622         unsigned int state = profile->file.start;
 623         struct aa_perms perms = {};
 624         const char *xname = NULL, *info = "change_profile onexec";
 625         int error = -EACCES;
 626
 627         AA_BUG(!profile);
 628         AA_BUG(!onexec);
 629         AA_BUG(!bprm);
 630         AA_BUG(!buffer);
 631
 632         if (profile_unconfined(profile)) {
 633                 /* change_profile on exec already granted */
 634                 /*
 635                  * NOTE: Domain transitions from unconfined are allowed
 636                  * even when no_new_privs is set because this aways results
 637                  * in a further reduction of permissions.
 638                  */
 639                 return 0;
 640         }
 641
 642         error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
 643                              &xname, &info, profile->disconnected);
 644         if (error) {
 645                 if (profile_unconfined(profile) ||
 646                     (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
 647                         AA_DEBUG("name lookup ix on error");
 648                         error = 0;
 649                 }
 650                 xname = bprm->filename;
 651                 goto audit;
 652         }
 653
 654         /* find exec permissions for name */
 655         state = aa_str_perms(profile->file.dfa, state, xname, cond, &perms);
 656         if (!(perms.allow & AA_MAY_ONEXEC)) {
 657                 info = "no change_onexec valid for executable";
 658                 goto audit;
 659         }
 660         /* test if this exec can be paired with change_profile onexec.
 661          * onexec permission is linked to exec with a standard pairing
 662          * exec\0change_profile
 663          */
 664         state = aa_dfa_null_transition(profile->file.dfa, state);
 665         error = change_profile_perms(profile, onexec, stack, AA_MAY_ONEXEC,
 666                                      state, &perms);
 667         if (error) {
 668                 perms.allow &= ~AA_MAY_ONEXEC;
 669                 goto audit;
 670         }
 671
 672         if (!(perms.xindex & AA_X_UNSAFE)) {
 673                 if (DEBUG_ON) {
 674                         dbg_printk("apparmor: scrubbing environment "
 675                                    "variables for %s label=", xname);
 676                         aa_label_printk(onexec, GFP_ATOMIC);
 677                         dbg_printk("\n");
 678                 }
 679                 *secure_exec = true;
 680         }
 681
 682 audit:
 683         return aa_audit_file(profile, &perms, OP_EXEC, AA_MAY_ONEXEC, xname,
 684                              NULL, onexec, cond->uid, info, error);
 685 }
 686
 687 /* ensure none ns domain transitions are correctly applied with onexec */
 688
 689 static struct aa_label *handle_onexec(struct aa_label *label,
 690                                       struct aa_label *onexec, bool stack,
 691                                       const struct linux_binprm *bprm,
 692                                       char *buffer, struct path_cond *cond,
 693                                       bool *unsafe)
 694 {
 695         struct aa_profile *profile;
 696         struct aa_label *new;
 697         int error;
 698
 699         AA_BUG(!label);
 700         AA_BUG(!onexec);
 701         AA_BUG(!bprm);
 702         AA_BUG(!buffer);
 703
 704         if (!stack) {
 705                 error = fn_for_each_in_ns(label, profile,
 706                                 profile_onexec(profile, onexec, stack,
 707                                                bprm, buffer, cond, unsafe));
 708                 if (error)
 709                         return ERR_PTR(error);
 710                 new = fn_label_build_in_ns(label, profile, GFP_ATOMIC,
 711                                 aa_get_newest_label(onexec),
 712                                 profile_transition(profile, bprm, buffer,
 713                                                    cond, unsafe));
 714
 715         } else {
 716                 /* TODO: determine how much we want to losen this */
 717                 error = fn_for_each_in_ns(label, profile,
 718                                 profile_onexec(profile, onexec, stack, bprm,
 719                                                buffer, cond, unsafe));
 720                 if (error)
 721                         return ERR_PTR(error);
 722                 new = fn_label_build_in_ns(label, profile, GFP_ATOMIC,
 723                                 aa_label_merge(&profile->label, onexec,
 724                                                GFP_ATOMIC),
 725                                 profile_transition(profile, bprm, buffer,
 726                                                    cond, unsafe));
 727         }
 728
 729         if (new)
 730                 return new;
 731
 732         /* TODO: get rid of GLOBAL_ROOT_UID */
 733         error = fn_for_each_in_ns(label, profile,
 734                         aa_audit_file(profile, &nullperms, OP_CHANGE_ONEXEC,
 735                                       AA_MAY_ONEXEC, bprm->filename, NULL,
 736                                       onexec, GLOBAL_ROOT_UID,
 737                                       "failed to build target label", -ENOMEM));
 738         return ERR_PTR(error);
 739 }
 740
 741 /**
 742  * apparmor_bprm_set_creds - set the new creds on the bprm struct
 743  * @bprm: binprm for the exec  (NOT NULL)
 744  *
 745  * Returns: %0 or error on failure
 746  *
 747  * TODO: once the other paths are done see if we can't refactor into a fn
 748  */
 749 int apparmor_bprm_set_creds(struct linux_binprm *bprm)
 750 {
 751         struct aa_task_ctx *ctx;
 752         struct aa_label *label, *new = NULL;
 753         struct aa_profile *profile;
 754         char *buffer = NULL;
 755         const char *info = NULL;
 756         int error = 0;
 757         bool unsafe = false;
 758         struct path_cond cond = {
 759                 file_inode(bprm->file)->i_uid,
 760                 file_inode(bprm->file)->i_mode
 761         };
 762
 763         if (bprm->called_set_creds)
 764                 return 0;
 765
 766         ctx = cred_ctx(bprm->cred);
 767         AA_BUG(!ctx);
 768
 769         label = aa_get_newest_label(ctx->label);
 770
 771         /* buffer freed below, name is pointer into buffer */
 772         get_buffers(buffer);
 773         /* Test for onexec first as onexec override other x transitions. */
 774         if (ctx->onexec)
 775                 new = handle_onexec(label, ctx->onexec, ctx->token,
 776                                     bprm, buffer, &cond, &unsafe);
 777         else
 778                 new = fn_label_build(label, profile, GFP_ATOMIC,
 779                                 profile_transition(profile, bprm, buffer,
 780                                                    &cond, &unsafe));
 781
 782         AA_BUG(!new);
 783         if (IS_ERR(new)) {
 784                 error = PTR_ERR(new);
 785                 goto done;
 786         } else if (!new) {
 787                 error = -ENOMEM;
 788                 goto done;
 789         }
 790
 791         /* Policy has specified a domain transitions. If no_new_privs and
 792          * confined ensure the transition is to confinement that is subset
 793          * of the confinement when the task entered no new privs.
 794          *
 795          * NOTE: Domain transitions from unconfined and to stacked
 796          * subsets are allowed even when no_new_privs is set because this
 797          * aways results in a further reduction of permissions.
 798          */
 799         if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) &&
 800             !unconfined(label) && !aa_label_is_subset(new, label)) {
 801                 error = -EPERM;
 802                 info = "no new privs";
 803                 goto audit;
 804         }
 805
 806         if (bprm->unsafe & LSM_UNSAFE_SHARE) {
 807                 /* FIXME: currently don't mediate shared state */
 808                 ;
 809         }
 810
 811         if (bprm->unsafe & (LSM_UNSAFE_PTRACE)) {
 812                 /* TODO: test needs to be profile of label to new */
 813                 error = may_change_ptraced_domain(new, &info);
 814                 if (error)
 815                         goto audit;
 816         }
 817
 818         if (unsafe) {
 819                 if (DEBUG_ON) {
 820                         dbg_printk("scrubbing environment variables for %s "
 821                                    "label=", bprm->filename);
 822                         aa_label_printk(new, GFP_ATOMIC);
 823                         dbg_printk("\n");
 824                 }
 825                 bprm->secureexec = 1;
 826         }
 827
 828         if (label->proxy != new->proxy) {
 829                 /* when transitioning clear unsafe personality bits */
 830                 if (DEBUG_ON) {
 831                         dbg_printk("apparmor: clearing unsafe personality "
 832                                    "bits. %s label=", bprm->filename);
 833                         aa_label_printk(new, GFP_ATOMIC);
 834                         dbg_printk("\n");
 835                 }
 836                 bprm->per_clear |= PER_CLEAR_ON_SETID;
 837         }
 838         aa_put_label(ctx->label);
 839         /* transfer reference, released when ctx is freed */
 840         ctx->label = new;
 841
 842 done:
 843         /* clear out temporary/transitional state from the context */
 844         aa_clear_task_ctx_trans(ctx);
 845
 846         aa_put_label(label);
 847         put_buffers(buffer);
 848
 849         return error;
 850
 851 audit:
 852         error = fn_for_each(label, profile,
 853                         aa_audit_file(profile, &nullperms, OP_EXEC, MAY_EXEC,
 854                                       bprm->filename, NULL, new,
 855                                       file_inode(bprm->file)->i_uid, info,
 856                                       error));
 857         aa_put_label(new);
 858         goto done;
 859 }
 860
 861 /*
 862  * Functions for self directed profile change
 863  */
 864
 865
 866 /* helper fn for change_hat
 867  *
 868  * Returns: label for hat transition OR ERR_PTR.  Does NOT return NULL
 869  */
 870 static struct aa_label *build_change_hat(struct aa_profile *profile,
 871                                          const char *name, bool sibling)
 872 {
 873         struct aa_profile *root, *hat = NULL;
 874         const char *info = NULL;
 875         int error = 0;
 876
 877         if (sibling && PROFILE_IS_HAT(profile)) {
 878                 root = aa_get_profile_rcu(&profile->parent);
 879         } else if (!sibling && !PROFILE_IS_HAT(profile)) {
 880                 root = aa_get_profile(profile);
 881         } else {
 882                 info = "conflicting target types";
 883                 error = -EPERM;
 884                 goto audit;
 885         }
 886
 887         hat = aa_find_child(root, name);
 888         if (!hat) {
 889                 error = -ENOENT;
 890                 if (COMPLAIN_MODE(profile)) {
 891                         hat = aa_new_null_profile(profile, true, name,
 892                                                   GFP_KERNEL);
 893                         if (!hat) {
 894                                 info = "failed null profile create";
 895                                 error = -ENOMEM;
 896                         }
 897                 }
 898         }
 899         aa_put_profile(root);
 900
 901 audit:
 902         aa_audit_file(profile, &nullperms, OP_CHANGE_HAT, AA_MAY_CHANGEHAT,
 903                       name, hat ? hat->base.hname : NULL,
 904                       hat ? &hat->label : NULL, GLOBAL_ROOT_UID, NULL,
 905                       error);
 906         if (!hat || (error && error != -ENOENT))
 907                 return ERR_PTR(error);
 908         /* if hat && error - complain mode, already audited and we adjust for
 909          * complain mode allow by returning hat->label
 910          */
 911         return &hat->label;
 912 }
 913
 914 /* helper fn for changing into a hat
 915  *
 916  * Returns: label for hat transition or ERR_PTR. Does not return NULL
 917  */
 918 static struct aa_label *change_hat(struct aa_label *label, const char *hats[],
 919                                    int count, int flags)
 920 {
 921         struct aa_profile *profile, *root, *hat = NULL;
 922         struct aa_label *new;
 923         struct label_it it;
 924         bool sibling = false;
 925         const char *name, *info = NULL;
 926         int i, error;
 927
 928         AA_BUG(!label);
 929         AA_BUG(!hats);
 930         AA_BUG(count < 1);
 931
 932         if (PROFILE_IS_HAT(labels_profile(label)))
 933                 sibling = true;
 934
 935         /*find first matching hat */
 936         for (i = 0; i < count && !hat; i++) {
 937                 name = hats[i];
 938                 label_for_each_in_ns(it, labels_ns(label), label, profile) {
 939                         if (sibling && PROFILE_IS_HAT(profile)) {
 940                                 root = aa_get_profile_rcu(&profile->parent);
 941                         } else if (!sibling && !PROFILE_IS_HAT(profile)) {
 942                                 root = aa_get_profile(profile);
 943                         } else {        /* conflicting change type */
 944                                 info = "conflicting targets types";
 945                                 error = -EPERM;
 946                                 goto fail;
 947                         }
 948                         hat = aa_find_child(root, name);
 949                         aa_put_profile(root);
 950                         if (!hat) {
 951                                 if (!COMPLAIN_MODE(profile))
 952                                         goto outer_continue;
 953                                 /* complain mode succeed as if hat */
 954                         } else if (!PROFILE_IS_HAT(hat)) {
 955                                 info = "target not hat";
 956                                 error = -EPERM;
 957                                 aa_put_profile(hat);
 958                                 goto fail;
 959                         }
 960                         aa_put_profile(hat);
 961                 }
 962                 /* found a hat for all profiles in ns */
 963                 goto build;
 964 outer_continue:
 965         ;
 966         }
 967         /* no hats that match, find appropriate error
 968          *
 969          * In complain mode audit of the failure is based off of the first
 970          * hat supplied.  This is done due how userspace interacts with
 971          * change_hat.
 972          */
 973         name = NULL;
 974         label_for_each_in_ns(it, labels_ns(label), label, profile) {
 975                 if (!list_empty(&profile->base.profiles)) {
 976                         info = "hat not found";
 977                         error = -ENOENT;
 978                         goto fail;
 979                 }
 980         }
 981         info = "no hats defined";
 982         error = -ECHILD;
 983
 984 fail:
 985         label_for_each_in_ns(it, labels_ns(label), label, profile) {
 986                 /*
 987                  * no target as it has failed to be found or built
 988                  *
 989                  * change_hat uses probing and should not log failures
 990                  * related to missing hats
 991                  */
 992                 /* TODO: get rid of GLOBAL_ROOT_UID */
 993                 if (count > 1 || COMPLAIN_MODE(profile)) {
 994                         aa_audit_file(profile, &nullperms, OP_CHANGE_HAT,
 995                                       AA_MAY_CHANGEHAT, name, NULL, NULL,
 996                                       GLOBAL_ROOT_UID, info, error);
 997                 }
 998         }
 999         return ERR_PTR(error);
1000
1001 build:
1002         new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
1003                                    build_change_hat(profile, name, sibling),
1004                                    aa_get_label(&profile->label));
1005         if (!new) {
1006                 info = "label build failed";
1007                 error = -ENOMEM;
1008                 goto fail;
1009         } /* else if (IS_ERR) build_change_hat has logged error so return new */
1010
1011         return new;
1012 }
1013
1014 /**
1015  * aa_change_hat - change hat to/from subprofile
1016  * @hats: vector of hat names to try changing into (MAYBE NULL if @count == 0)
1017  * @count: number of hat names in @hats
1018  * @token: magic value to validate the hat change
1019  * @flags: flags affecting behavior of the change
1020  *
1021  * Returns %0 on success, error otherwise.
1022  *
1023  * Change to the first profile specified in @hats that exists, and store
1024  * the @hat_magic in the current task context.  If the count == 0 and the
1025  * @token matches that stored in the current task context, return to the
1026  * top level profile.
1027  *
1028  * change_hat only applies to profiles in the current ns, and each profile
1029  * in the ns must make the same transition otherwise change_hat will fail.
1030  */
1031 int aa_change_hat(const char *hats[], int count, u64 token, int flags)
1032 {
1033         const struct cred *cred;
1034         struct aa_task_ctx *ctx;
1035         struct aa_label *label, *previous, *new = NULL, *target = NULL;
1036         struct aa_profile *profile;
1037         struct aa_perms perms = {};
1038         const char *info = NULL;
1039         int error = 0;
1040
1041         /*
1042          * Fail explicitly requested domain transitions if no_new_privs.
1043          * There is no exception for unconfined as change_hat is not
1044          * available.
1045          */
1046         if (task_no_new_privs(current)) {
1047                 /* not an apparmor denial per se, so don't log it */
1048                 AA_DEBUG("no_new_privs - change_hat denied");
1049                 return -EPERM;
1050         }
1051
1052         /* released below */
1053         cred = get_current_cred();
1054         ctx = cred_ctx(cred);
1055         label = aa_get_newest_cred_label(cred);
1056         previous = aa_get_newest_label(ctx->previous);
1057
1058         if (unconfined(label)) {
1059                 info = "unconfined can not change_hat";
1060                 error = -EPERM;
1061                 goto fail;
1062         }
1063
1064         if (count) {
1065                 new = change_hat(label, hats, count, flags);
1066                 AA_BUG(!new);
1067                 if (IS_ERR(new)) {
1068                         error = PTR_ERR(new);
1069                         new = NULL;
1070                         /* already audited */
1071                         goto out;
1072                 }
1073
1074                 error = may_change_ptraced_domain(new, &info);
1075                 if (error)
1076                         goto fail;
1077
1078                 if (flags & AA_CHANGE_TEST)
1079                         goto out;
1080
1081                 target = new;
1082                 error = aa_set_current_hat(new, token);
1083                 if (error == -EACCES)
1084                         /* kill task in case of brute force attacks */
1085                         goto kill;
1086         } else if (previous && !(flags & AA_CHANGE_TEST)) {
1087                 /* Return to saved label.  Kill task if restore fails
1088                  * to avoid brute force attacks
1089                  */
1090                 target = previous;
1091                 error = aa_restore_previous_label(token);
1092                 if (error) {
1093                         if (error == -EACCES)
1094                                 goto kill;
1095                         goto fail;
1096                 }
1097         } /* else ignore @flags && restores when there is no saved profile */
1098
1099 out:
1100         aa_put_label(new);
1101         aa_put_label(previous);
1102         aa_put_label(label);
1103         put_cred(cred);
1104
1105         return error;
1106
1107 kill:
1108         info = "failed token match";
1109         perms.kill = AA_MAY_CHANGEHAT;
1110
1111 fail:
1112         fn_for_each_in_ns(label, profile,
1113                 aa_audit_file(profile, &perms, OP_CHANGE_HAT,
1114                               AA_MAY_CHANGEHAT, NULL, NULL, target,
1115                               GLOBAL_ROOT_UID, info, error));
1116
1117         goto out;
1118 }
1119
1120
1121 static int change_profile_perms_wrapper(const char *op, const char *name,
1122                                         struct aa_profile *profile,
1123                                         struct aa_label *target, bool stack,
1124                                         u32 request, struct aa_perms *perms)
1125 {
1126         const char *info = NULL;
1127         int error = 0;
1128
1129         /*
1130          * Fail explicitly requested domain transitions when no_new_privs
1131          * and not unconfined OR the transition results in a stack on
1132          * the current label.
1133          * Stacking domain transitions and transitions from unconfined are
1134          * allowed even when no_new_privs is set because this aways results
1135          * in a reduction of permissions.
1136          */
1137         if (task_no_new_privs(current) && !stack &&
1138             !profile_unconfined(profile) &&
1139             !aa_label_is_subset(target, &profile->label)) {
1140                 info = "no new privs";
1141                 error = -EPERM;
1142         }
1143
1144         if (!error)
1145                 error = change_profile_perms(profile, target, stack, request,
1146                                              profile->file.start, perms);
1147         if (error)
1148                 error = aa_audit_file(profile, perms, op, request, name,
1149                                       NULL, target, GLOBAL_ROOT_UID, info,
1150                                       error);
1151
1152         return error;
1153 }
1154
1155 /**
1156  * aa_change_profile - perform a one-way profile transition
1157  * @fqname: name of profile may include namespace (NOT NULL)
1158  * @onexec: whether this transition is to take place immediately or at exec
1159  * @flags: flags affecting change behavior
1160  *
1161  * Change to new profile @name.  Unlike with hats, there is no way
1162  * to change back.  If @name isn't specified the current profile name is
1163  * used.
1164  * If @onexec then the transition is delayed until
1165  * the next exec.
1166  *
1167  * Returns %0 on success, error otherwise.
1168  */
1169 int aa_change_profile(const char *fqname, int flags)
1170 {
1171         struct aa_label *label, *new = NULL, *target = NULL;
1172         struct aa_profile *profile;
1173         struct aa_perms perms = {};
1174         const char *info = NULL;
1175         const char *auditname = fqname;         /* retain leading & if stack */
1176         bool stack = flags & AA_CHANGE_STACK;
1177         int error = 0;
1178         char *op;
1179         u32 request;
1180
1181         if (!fqname || !*fqname) {
1182                 AA_DEBUG("no profile name");
1183                 return -EINVAL;
1184         }
1185
1186         if (flags & AA_CHANGE_ONEXEC) {
1187                 request = AA_MAY_ONEXEC;
1188                 if (stack)
1189                         op = OP_STACK_ONEXEC;
1190                 else
1191                         op = OP_CHANGE_ONEXEC;
1192         } else {
1193                 request = AA_MAY_CHANGE_PROFILE;
1194                 if (stack)
1195                         op = OP_STACK;
1196                 else
1197                         op = OP_CHANGE_PROFILE;
1198         }
1199
1200         label = aa_get_current_label();
1201
1202         if (*fqname == '&') {
1203                 stack = true;
1204                 /* don't have label_parse() do stacking */
1205                 fqname++;
1206         }
1207         target = aa_label_parse(label, fqname, GFP_KERNEL, true, false);
1208         if (IS_ERR(target)) {
1209                 struct aa_profile *tprofile;
1210
1211                 info = "label not found";
1212                 error = PTR_ERR(target);
1213                 target = NULL;
1214                 /*
1215                  * TODO: fixme using labels_profile is not right - do profile
1216                  * per complain profile
1217                  */
1218                 if ((flags & AA_CHANGE_TEST) ||
1219                     !COMPLAIN_MODE(labels_profile(label)))
1220                         goto audit;
1221                 /* released below */
1222                 tprofile = aa_new_null_profile(labels_profile(label), false,
1223                                                fqname, GFP_KERNEL);
1224                 if (!tprofile) {
1225                         info = "failed null profile create";
1226                         error = -ENOMEM;
1227                         goto audit;
1228                 }
1229                 target = &tprofile->label;
1230                 goto check;
1231         }
1232
1233         /*
1234          * self directed transitions only apply to current policy ns
1235          * TODO: currently requiring perms for stacking and straight change
1236          *       stacking doesn't strictly need this. Determine how much
1237          *       we want to loosen this restriction for stacking
1238          *
1239          * if (!stack) {
1240          */
1241         error = fn_for_each_in_ns(label, profile,
1242                         change_profile_perms_wrapper(op, auditname,
1243                                                      profile, target, stack,
1244                                                      request, &perms));
1245         if (error)
1246                 /* auditing done in change_profile_perms_wrapper */
1247                 goto out;
1248
1249         /* } */
1250
1251 check:
1252         /* check if tracing task is allowed to trace target domain */
1253         error = may_change_ptraced_domain(target, &info);
1254         if (error && !fn_for_each_in_ns(label, profile,
1255                                         COMPLAIN_MODE(profile)))
1256                 goto audit;
1257
1258         /* TODO: add permission check to allow this
1259          * if ((flags & AA_CHANGE_ONEXEC) && !current_is_single_threaded()) {
1260          *      info = "not a single threaded task";
1261          *      error = -EACCES;
1262          *      goto audit;
1263          * }
1264          */
1265         if (flags & AA_CHANGE_TEST)
1266                 goto out;
1267
1268         if (!(flags & AA_CHANGE_ONEXEC)) {
1269                 /* only transition profiles in the current ns */
1270                 if (stack)
1271                         new = aa_label_merge(label, target, GFP_KERNEL);
1272                 else
1273                         new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
1274                                         aa_get_label(target),
1275                                         aa_get_label(&profile->label));
1276                 if (IS_ERR_OR_NULL(new)) {
1277                         info = "failed to build target label";
1278                         if (!new)
1279                                 error = -ENOMEM;
1280                         else
1281                                 error = PTR_ERR(new);
1282                         new = NULL;
1283                         perms.allow = 0;
1284                         goto audit;
1285                 }
1286                 error = aa_replace_current_label(new);
1287         } else
1288                 /* full transition will be built in exec path */
1289                 error = aa_set_current_onexec(target, stack);
1290
1291 audit:
1292         error = fn_for_each_in_ns(label, profile,
1293                         aa_audit_file(profile, &perms, op, request, auditname,
1294                                       NULL, new ? new : target,
1295                                       GLOBAL_ROOT_UID, info, error));
1296
1297 out:
1298         aa_put_label(new);
1299         aa_put_label(target);
1300         aa_put_label(label);
1301
1302         return error;
1303 }