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v4.17
   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#include <linux/xattr.h>
  23
  24#include "include/audit.h"
  25#include "include/apparmorfs.h"
  26#include "include/cred.h"
  27#include "include/domain.h"
  28#include "include/file.h"
  29#include "include/ipc.h"
  30#include "include/match.h"
  31#include "include/path.h"
  32#include "include/policy.h"
  33#include "include/policy_ns.h"
  34
  35/**
  36 * aa_free_domain_entries - free entries in a domain table
  37 * @domain: the domain table to free  (MAYBE NULL)
  38 */
  39void aa_free_domain_entries(struct aa_domain *domain)
  40{
  41	int i;
  42	if (domain) {
  43		if (!domain->table)
  44			return;
  45
  46		for (i = 0; i < domain->size; i++)
  47			kzfree(domain->table[i]);
  48		kzfree(domain->table);
  49		domain->table = NULL;
  50	}
  51}
  52
  53/**
  54 * may_change_ptraced_domain - check if can change profile on ptraced task
  55 * @to_label: profile to change to  (NOT NULL)
  56 * @info: message if there is an error
  57 *
  58 * Check if current is ptraced and if so if the tracing task is allowed
  59 * to trace the new domain
  60 *
  61 * Returns: %0 or error if change not allowed
  62 */
  63static int may_change_ptraced_domain(struct aa_label *to_label,
  64				     const char **info)
  65{
  66	struct task_struct *tracer;
  67	struct aa_label *tracerl = NULL;
 
  68	int error = 0;
  69
  70	rcu_read_lock();
  71	tracer = ptrace_parent(current);
  72	if (tracer)
  73		/* released below */
  74		tracerl = aa_get_task_label(tracer);
 
 
  75
  76	/* not ptraced */
  77	if (!tracer || unconfined(tracerl))
  78		goto out;
  79
  80	error = aa_may_ptrace(tracerl, to_label, PTRACE_MODE_ATTACH);
  81
  82out:
  83	rcu_read_unlock();
  84	aa_put_label(tracerl);
 
  85
  86	if (error)
  87		*info = "ptrace prevents transition";
  88	return error;
  89}
  90
  91/**** TODO: dedup to aa_label_match - needs perm and dfa, merging
  92 * specifically this is an exact copy of aa_label_match except
  93 * aa_compute_perms is replaced with aa_compute_fperms
  94 * and policy.dfa with file.dfa
  95 ****/
  96/* match a profile and its associated ns component if needed
  97 * Assumes visibility test has already been done.
  98 * If a subns profile is not to be matched should be prescreened with
  99 * visibility test.
 100 */
 101static inline unsigned int match_component(struct aa_profile *profile,
 102					   struct aa_profile *tp,
 103					   bool stack, unsigned int state)
 104{
 105	const char *ns_name;
 106
 107	if (stack)
 108		state = aa_dfa_match(profile->file.dfa, state, "&");
 109	if (profile->ns == tp->ns)
 110		return aa_dfa_match(profile->file.dfa, state, tp->base.hname);
 111
 112	/* try matching with namespace name and then profile */
 113	ns_name = aa_ns_name(profile->ns, tp->ns, true);
 114	state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
 115	state = aa_dfa_match(profile->file.dfa, state, ns_name);
 116	state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
 117	return aa_dfa_match(profile->file.dfa, state, tp->base.hname);
 118}
 119
 120/**
 121 * label_compound_match - find perms for full compound label
 122 * @profile: profile to find perms for
 123 * @label: label to check access permissions for
 124 * @stack: whether this is a stacking request
 125 * @start: state to start match in
 126 * @subns: whether to do permission checks on components in a subns
 127 * @request: permissions to request
 128 * @perms: perms struct to set
 129 *
 130 * Returns: 0 on success else ERROR
 131 *
 132 * For the label A//&B//&C this does the perm match for A//&B//&C
 133 * @perms should be preinitialized with allperms OR a previous permission
 134 *        check to be stacked.
 135 */
 136static int label_compound_match(struct aa_profile *profile,
 137				struct aa_label *label, bool stack,
 138				unsigned int state, bool subns, u32 request,
 139				struct aa_perms *perms)
 140{
 141	struct aa_profile *tp;
 142	struct label_it i;
 143	struct path_cond cond = { };
 144
 145	/* find first subcomponent that is visible */
 146	label_for_each(i, label, tp) {
 147		if (!aa_ns_visible(profile->ns, tp->ns, subns))
 148			continue;
 149		state = match_component(profile, tp, stack, state);
 150		if (!state)
 151			goto fail;
 152		goto next;
 153	}
 154
 155	/* no component visible */
 156	*perms = allperms;
 157	return 0;
 158
 159next:
 160	label_for_each_cont(i, label, tp) {
 161		if (!aa_ns_visible(profile->ns, tp->ns, subns))
 162			continue;
 163		state = aa_dfa_match(profile->file.dfa, state, "//&");
 164		state = match_component(profile, tp, false, state);
 165		if (!state)
 166			goto fail;
 167	}
 168	*perms = aa_compute_fperms(profile->file.dfa, state, &cond);
 169	aa_apply_modes_to_perms(profile, perms);
 170	if ((perms->allow & request) != request)
 171		return -EACCES;
 172
 173	return 0;
 174
 175fail:
 176	*perms = nullperms;
 177	return -EACCES;
 178}
 179
 180/**
 181 * label_components_match - find perms for all subcomponents of a label
 182 * @profile: profile to find perms for
 183 * @label: label to check access permissions for
 184 * @stack: whether this is a stacking request
 185 * @start: state to start match in
 186 * @subns: whether to do permission checks on components in a subns
 187 * @request: permissions to request
 188 * @perms: an initialized perms struct to add accumulation to
 189 *
 190 * Returns: 0 on success else ERROR
 191 *
 192 * For the label A//&B//&C this does the perm match for each of A and B and C
 193 * @perms should be preinitialized with allperms OR a previous permission
 194 *        check to be stacked.
 195 */
 196static int label_components_match(struct aa_profile *profile,
 197				  struct aa_label *label, bool stack,
 198				  unsigned int start, bool subns, u32 request,
 199				  struct aa_perms *perms)
 200{
 201	struct aa_profile *tp;
 202	struct label_it i;
 203	struct aa_perms tmp;
 204	struct path_cond cond = { };
 205	unsigned int state = 0;
 206
 207	/* find first subcomponent to test */
 208	label_for_each(i, label, tp) {
 209		if (!aa_ns_visible(profile->ns, tp->ns, subns))
 210			continue;
 211		state = match_component(profile, tp, stack, start);
 212		if (!state)
 213			goto fail;
 214		goto next;
 215	}
 216
 217	/* no subcomponents visible - no change in perms */
 218	return 0;
 219
 220next:
 221	tmp = aa_compute_fperms(profile->file.dfa, state, &cond);
 222	aa_apply_modes_to_perms(profile, &tmp);
 223	aa_perms_accum(perms, &tmp);
 224	label_for_each_cont(i, label, tp) {
 225		if (!aa_ns_visible(profile->ns, tp->ns, subns))
 226			continue;
 227		state = match_component(profile, tp, stack, start);
 228		if (!state)
 229			goto fail;
 230		tmp = aa_compute_fperms(profile->file.dfa, state, &cond);
 231		aa_apply_modes_to_perms(profile, &tmp);
 232		aa_perms_accum(perms, &tmp);
 233	}
 234
 235	if ((perms->allow & request) != request)
 236		return -EACCES;
 237
 238	return 0;
 239
 240fail:
 241	*perms = nullperms;
 242	return -EACCES;
 243}
 244
 245/**
 246 * label_match - do a multi-component label match
 247 * @profile: profile to match against (NOT NULL)
 248 * @label: label to match (NOT NULL)
 249 * @stack: whether this is a stacking request
 250 * @state: state to start in
 251 * @subns: whether to match subns components
 252 * @request: permission request
 253 * @perms: Returns computed perms (NOT NULL)
 254 *
 255 * Returns: the state the match finished in, may be the none matching state
 256 */
 257static int label_match(struct aa_profile *profile, struct aa_label *label,
 258		       bool stack, unsigned int state, bool subns, u32 request,
 259		       struct aa_perms *perms)
 260{
 261	int error;
 262
 263	*perms = nullperms;
 264	error = label_compound_match(profile, label, stack, state, subns,
 265				     request, perms);
 266	if (!error)
 267		return error;
 268
 269	*perms = allperms;
 270	return label_components_match(profile, label, stack, state, subns,
 271				      request, perms);
 272}
 273
 274/******* end TODO: dedup *****/
 275
 276/**
 277 * change_profile_perms - find permissions for change_profile
 278 * @profile: the current profile  (NOT NULL)
 279 * @target: label to transition to (NOT NULL)
 280 * @stack: whether this is a stacking request
 281 * @request: requested perms
 282 * @start: state to start matching in
 283 *
 284 *
 285 * Returns: permission set
 286 *
 287 * currently only matches full label A//&B//&C or individual components A, B, C
 288 * not arbitrary combinations. Eg. A//&B, C
 289 */
 290static int change_profile_perms(struct aa_profile *profile,
 291				struct aa_label *target, bool stack,
 292				u32 request, unsigned int start,
 293				struct aa_perms *perms)
 294{
 295	if (profile_unconfined(profile)) {
 296		perms->allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC;
 297		perms->audit = perms->quiet = perms->kill = 0;
 298		return 0;
 299	}
 300
 301	/* TODO: add profile in ns screening */
 302	return label_match(profile, target, stack, start, true, request, perms);
 303}
 304
 305/**
 306 * aa_xattrs_match - check whether a file matches the xattrs defined in profile
 307 * @bprm: binprm struct for the process to validate
 308 * @profile: profile to match against (NOT NULL)
 309 * @state: state to start match in
 310 *
 311 * Returns: number of extended attributes that matched, or < 0 on error
 312 */
 313static int aa_xattrs_match(const struct linux_binprm *bprm,
 314			   struct aa_profile *profile, unsigned int state)
 
 
 315{
 316	int i;
 317	ssize_t size;
 318	struct dentry *d;
 319	char *value = NULL;
 320	int value_size = 0, ret = profile->xattr_count;
 321
 322	if (!bprm || !profile->xattr_count)
 323		return 0;
 324
 325	/* transition from exec match to xattr set */
 326	state = aa_dfa_null_transition(profile->xmatch, state);
 327
 328	d = bprm->file->f_path.dentry;
 329
 330	for (i = 0; i < profile->xattr_count; i++) {
 331		size = vfs_getxattr_alloc(d, profile->xattrs[i], &value,
 332					  value_size, GFP_KERNEL);
 333		if (size >= 0) {
 334			u32 perm;
 335
 336			/* Check the xattr value, not just presence */
 337			state = aa_dfa_match_len(profile->xmatch, state, value,
 338						 size);
 339			perm = dfa_user_allow(profile->xmatch, state);
 340			if (!(perm & MAY_EXEC)) {
 341				ret = -EINVAL;
 342				goto out;
 343			}
 344		}
 345		/* transition to next element */
 346		state = aa_dfa_null_transition(profile->xmatch, state);
 347		if (size < 0) {
 348			/*
 349			 * No xattr match, so verify if transition to
 350			 * next element was valid. IFF so the xattr
 351			 * was optional.
 352			 */
 353			if (!state) {
 354				ret = -EINVAL;
 355				goto out;
 356			}
 357			/* don't count missing optional xattr as matched */
 358			ret--;
 359		}
 360	}
 361
 362out:
 363	kfree(value);
 364	return ret;
 
 
 
 365}
 366
 367/**
 368 * __attach_match_ - find an attachment match
 369 * @bprm - binprm structure of transitioning task
 370 * @name - to match against  (NOT NULL)
 371 * @head - profile list to walk  (NOT NULL)
 372 * @info - info message if there was an error (NOT NULL)
 373 *
 374 * Do a linear search on the profiles in the list.  There is a matching
 375 * preference where an exact match is preferred over a name which uses
 376 * expressions to match, and matching expressions with the greatest
 377 * xmatch_len are preferred.
 378 *
 379 * Requires: @head not be shared or have appropriate locks held
 380 *
 381 * Returns: profile or NULL if no match found
 382 */
 383static struct aa_profile *__attach_match(const struct linux_binprm *bprm,
 384					 const char *name,
 385					 struct list_head *head,
 386					 const char **info)
 387{
 388	int candidate_len = 0, candidate_xattrs = 0;
 389	bool conflict = false;
 390	struct aa_profile *profile, *candidate = NULL;
 391
 392	AA_BUG(!name);
 393	AA_BUG(!head);
 394
 395	list_for_each_entry_rcu(profile, head, base.list) {
 396		if (profile->label.flags & FLAG_NULL &&
 397		    &profile->label == ns_unconfined(profile->ns))
 398			continue;
 399
 400		/* Find the "best" matching profile. Profiles must
 401		 * match the path and extended attributes (if any)
 402		 * associated with the file. A more specific path
 403		 * match will be preferred over a less specific one,
 404		 * and a match with more matching extended attributes
 405		 * will be preferred over one with fewer. If the best
 406		 * match has both the same level of path specificity
 407		 * and the same number of matching extended attributes
 408		 * as another profile, signal a conflict and refuse to
 409		 * match.
 410		 */
 411		if (profile->xmatch) {
 412			unsigned int state, count;
 413			u32 perm;
 414
 415			state = aa_dfa_leftmatch(profile->xmatch, DFA_START,
 416						 name, &count);
 417			perm = dfa_user_allow(profile->xmatch, state);
 418			/* any accepting state means a valid match. */
 419			if (perm & MAY_EXEC) {
 420				int ret;
 421
 422				if (count < candidate_len)
 423					continue;
 424
 425				ret = aa_xattrs_match(bprm, profile, state);
 426				/* Fail matching if the xattrs don't match */
 427				if (ret < 0)
 428					continue;
 429
 430				/*
 431				 * TODO: allow for more flexible best match
 432				 *
 433				 * The new match isn't more specific
 434				 * than the current best match
 435				 */
 436				if (count == candidate_len &&
 437				    ret <= candidate_xattrs) {
 438					/* Match is equivalent, so conflict */
 439					if (ret == candidate_xattrs)
 440						conflict = true;
 441					continue;
 442				}
 443
 444				/* Either the same length with more matching
 445				 * xattrs, or a longer match
 446				 */
 447				candidate = profile;
 448				candidate_len = profile->xmatch_len;
 449				candidate_xattrs = ret;
 450				conflict = false;
 451			}
 452		} else if (!strcmp(profile->base.name, name))
 453			/*
 454			 * old exact non-re match, without conditionals such
 455			 * as xattrs. no more searching required
 456			 */
 457			return profile;
 458	}
 459
 460	if (conflict) {
 461		*info = "conflicting profile attachments";
 462		return NULL;
 463	}
 464
 465	return candidate;
 466}
 467
 468/**
 469 * find_attach - do attachment search for unconfined processes
 470 * @bprm - binprm structure of transitioning task
 471 * @ns: the current namespace  (NOT NULL)
 472 * @list: list to search  (NOT NULL)
 473 * @name: the executable name to match against  (NOT NULL)
 474 * @info: info message if there was an error
 475 *
 476 * Returns: label or NULL if no match found
 477 */
 478static struct aa_label *find_attach(const struct linux_binprm *bprm,
 479				    struct aa_ns *ns, struct list_head *list,
 480				    const char *name, const char **info)
 481{
 482	struct aa_profile *profile;
 483
 484	rcu_read_lock();
 485	profile = aa_get_profile(__attach_match(bprm, name, list, info));
 486	rcu_read_unlock();
 
 
 
 487
 488	return profile ? &profile->label : NULL;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 489}
 490
 491static const char *next_name(int xtype, const char *name)
 492{
 493	return NULL;
 494}
 495
 496/**
 497 * x_table_lookup - lookup an x transition name via transition table
 498 * @profile: current profile (NOT NULL)
 499 * @xindex: index into x transition table
 500 * @name: returns: name tested to find label (NOT NULL)
 501 *
 502 * Returns: refcounted label, or NULL on failure (MAYBE NULL)
 503 */
 504struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
 505				const char **name)
 506{
 507	struct aa_label *label = NULL;
 
 508	u32 xtype = xindex & AA_X_TYPE_MASK;
 509	int index = xindex & AA_X_INDEX_MASK;
 510
 511	AA_BUG(!name);
 512
 513	/* index is guaranteed to be in range, validated at load time */
 514	/* TODO: move lookup parsing to unpack time so this is a straight
 515	 *       index into the resultant label
 516	 */
 517	for (*name = profile->file.trans.table[index]; !label && *name;
 518	     *name = next_name(xtype, *name)) {
 
 519		if (xindex & AA_X_CHILD) {
 520			struct aa_profile *new_profile;
 521			/* release by caller */
 522			new_profile = aa_find_child(profile, *name);
 523			if (new_profile)
 524				label = &new_profile->label;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 525			continue;
 
 
 
 526		}
 527		label = aa_label_parse(&profile->label, *name, GFP_ATOMIC,
 528				       true, false);
 529		if (IS_ERR(label))
 530			label = NULL;
 531	}
 532
 533	/* released by caller */
 534
 535	return label;
 536}
 537
 538/**
 539 * x_to_label - get target label for a given xindex
 540 * @profile: current profile  (NOT NULL)
 541 * @bprm: binprm structure of transitioning task
 542 * @name: name to lookup (NOT NULL)
 543 * @xindex: index into x transition table
 544 * @lookupname: returns: name used in lookup if one was specified (NOT NULL)
 545 *
 546 * find label for a transition index
 547 *
 548 * Returns: refcounted label or NULL if not found available
 549 */
 550static struct aa_label *x_to_label(struct aa_profile *profile,
 551				   const struct linux_binprm *bprm,
 552				   const char *name, u32 xindex,
 553				   const char **lookupname,
 554				   const char **info)
 555{
 556	struct aa_label *new = NULL;
 557	struct aa_ns *ns = profile->ns;
 558	u32 xtype = xindex & AA_X_TYPE_MASK;
 559	const char *stack = NULL;
 560
 561	switch (xtype) {
 562	case AA_X_NONE:
 563		/* fail exec unless ix || ux fallback - handled by caller */
 564		*lookupname = NULL;
 565		break;
 566	case AA_X_TABLE:
 567		/* TODO: fix when perm mapping done at unload */
 568		stack = profile->file.trans.table[xindex & AA_X_INDEX_MASK];
 569		if (*stack != '&') {
 570			/* released by caller */
 571			new = x_table_lookup(profile, xindex, lookupname);
 572			stack = NULL;
 573			break;
 574		}
 575		/* fall through to X_NAME */
 576	case AA_X_NAME:
 577		if (xindex & AA_X_CHILD)
 578			/* released by caller */
 579			new = find_attach(bprm, ns, &profile->base.profiles,
 580					  name, info);
 581		else
 582			/* released by caller */
 583			new = find_attach(bprm, ns, &ns->base.profiles,
 584					  name, info);
 585		*lookupname = name;
 
 
 
 586		break;
 587	}
 588
 589	if (!new) {
 590		if (xindex & AA_X_INHERIT) {
 591			/* (p|c|n)ix - don't change profile but do
 592			 * use the newest version
 593			 */
 594			*info = "ix fallback";
 595			/* no profile && no error */
 596			new = aa_get_newest_label(&profile->label);
 597		} else if (xindex & AA_X_UNCONFINED) {
 598			new = aa_get_newest_label(ns_unconfined(profile->ns));
 599			*info = "ux fallback";
 600		}
 601	}
 602
 603	if (new && stack) {
 604		/* base the stack on post domain transition */
 605		struct aa_label *base = new;
 606
 607		new = aa_label_parse(base, stack, GFP_ATOMIC, true, false);
 608		if (IS_ERR(new))
 609			new = NULL;
 610		aa_put_label(base);
 611	}
 612
 613	/* released by caller */
 614	return new;
 615}
 616
 617static struct aa_label *profile_transition(struct aa_profile *profile,
 618					   const struct linux_binprm *bprm,
 619					   char *buffer, struct path_cond *cond,
 620					   bool *secure_exec)
 
 
 
 621{
 622	struct aa_label *new = NULL;
 623	struct aa_profile *component;
 624	struct label_it i;
 625	const char *info = NULL, *name = NULL, *target = NULL;
 626	unsigned int state = profile->file.start;
 627	struct aa_perms perms = {};
 628	bool nonewprivs = false;
 629	int error = 0;
 
 
 
 
 
 
 630
 631	AA_BUG(!profile);
 632	AA_BUG(!bprm);
 633	AA_BUG(!buffer);
 
 
 
 
 
 
 
 
 
 
 634
 635	error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
 636			     &name, &info, profile->disconnected);
 
 637	if (error) {
 638		if (profile_unconfined(profile) ||
 639		    (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
 640			AA_DEBUG("name lookup ix on error");
 641			error = 0;
 642			new = aa_get_newest_label(&profile->label);
 643		}
 644		name = bprm->filename;
 645		goto audit;
 646	}
 647
 648	if (profile_unconfined(profile)) {
 649		new = find_attach(bprm, profile->ns,
 650				  &profile->ns->base.profiles, name, &info);
 651		if (new) {
 652			AA_DEBUG("unconfined attached to new label");
 653			return new;
 654		}
 655		AA_DEBUG("unconfined exec no attachment");
 656		return aa_get_newest_label(&profile->label);
 
 
 
 
 
 
 
 
 
 657	}
 658
 659	/* find exec permissions for name */
 660	state = aa_str_perms(profile->file.dfa, state, name, cond, &perms);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 661	if (perms.allow & MAY_EXEC) {
 662		/* exec permission determine how to transition */
 663		new = x_to_label(profile, bprm, name, perms.xindex, &target,
 664				 &info);
 665		if (new && new->proxy == profile->label.proxy && info) {
 666			/* hack ix fallback - improve how this is detected */
 667			goto audit;
 668		} else if (!new) {
 669			error = -EACCES;
 670			info = "profile transition not found";
 671			/* remove MAY_EXEC to audit as failure */
 672			perms.allow &= ~MAY_EXEC;
 673		} else {
 674			/* verify that each component's xattr requirements are
 675			 * met, and fail execution otherwise
 676			 */
 677			label_for_each(i, new, component) {
 678				if (aa_xattrs_match(bprm, component, state) <
 679				    0) {
 680					error = -EACCES;
 681					info = "required xattrs not present";
 682					perms.allow &= ~MAY_EXEC;
 683					aa_put_label(new);
 684					new = NULL;
 685					goto audit;
 686				}
 687			}
 688		}
 689	} else if (COMPLAIN_MODE(profile)) {
 690		/* no exec permission - learning mode */
 691		struct aa_profile *new_profile = NULL;
 692		char *n = kstrdup(name, GFP_ATOMIC);
 693
 694		if (n) {
 695			/* name is ptr into buffer */
 696			long pos = name - buffer;
 697			/* break per cpu buffer hold */
 698			put_buffers(buffer);
 699			new_profile = aa_new_null_profile(profile, false, n,
 700							  GFP_KERNEL);
 701			get_buffers(buffer);
 702			name = buffer + pos;
 703			strcpy((char *)name, n);
 704			kfree(n);
 705		}
 706		if (!new_profile) {
 707			error = -ENOMEM;
 708			info = "could not create null profile";
 709		} else {
 710			error = -EACCES;
 711			new = &new_profile->label;
 712		}
 713		perms.xindex |= AA_X_UNSAFE;
 714	} else
 715		/* fail exec */
 716		error = -EACCES;
 717
 718	if (!new)
 719		goto audit;
 720
 721
 722	if (!(perms.xindex & AA_X_UNSAFE)) {
 723		if (DEBUG_ON) {
 724			dbg_printk("apparmor: scrubbing environment variables"
 725				   " for %s profile=", name);
 726			aa_label_printk(new, GFP_ATOMIC);
 727			dbg_printk("\n");
 728		}
 729		*secure_exec = true;
 730	}
 731
 732audit:
 733	aa_audit_file(profile, &perms, OP_EXEC, MAY_EXEC, name, target, new,
 734		      cond->uid, info, error);
 735	if (!new || nonewprivs) {
 736		aa_put_label(new);
 737		return ERR_PTR(error);
 738	}
 739
 740	return new;
 741}
 742
 743static int profile_onexec(struct aa_profile *profile, struct aa_label *onexec,
 744			  bool stack, const struct linux_binprm *bprm,
 745			  char *buffer, struct path_cond *cond,
 746			  bool *secure_exec)
 747{
 748	unsigned int state = profile->file.start;
 749	struct aa_perms perms = {};
 750	const char *xname = NULL, *info = "change_profile onexec";
 751	int error = -EACCES;
 752
 753	AA_BUG(!profile);
 754	AA_BUG(!onexec);
 755	AA_BUG(!bprm);
 756	AA_BUG(!buffer);
 757
 758	if (profile_unconfined(profile)) {
 759		/* change_profile on exec already granted */
 760		/*
 761		 * NOTE: Domain transitions from unconfined are allowed
 762		 * even when no_new_privs is set because this aways results
 763		 * in a further reduction of permissions.
 764		 */
 765		return 0;
 766	}
 767
 768	error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
 769			     &xname, &info, profile->disconnected);
 770	if (error) {
 771		if (profile_unconfined(profile) ||
 772		    (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
 773			AA_DEBUG("name lookup ix on error");
 774			error = 0;
 775		}
 776		xname = bprm->filename;
 777		goto audit;
 778	}
 779
 780	/* find exec permissions for name */
 781	state = aa_str_perms(profile->file.dfa, state, xname, cond, &perms);
 782	if (!(perms.allow & AA_MAY_ONEXEC)) {
 783		info = "no change_onexec valid for executable";
 784		goto audit;
 785	}
 786	/* test if this exec can be paired with change_profile onexec.
 787	 * onexec permission is linked to exec with a standard pairing
 788	 * exec\0change_profile
 
 
 789	 */
 790	state = aa_dfa_null_transition(profile->file.dfa, state);
 791	error = change_profile_perms(profile, onexec, stack, AA_MAY_ONEXEC,
 792				     state, &perms);
 793	if (error) {
 794		perms.allow &= ~AA_MAY_ONEXEC;
 795		goto audit;
 796	}
 797
 798	if (!(perms.xindex & AA_X_UNSAFE)) {
 799		if (DEBUG_ON) {
 800			dbg_printk("apparmor: scrubbing environment "
 801				   "variables for %s label=", xname);
 802			aa_label_printk(onexec, GFP_ATOMIC);
 803			dbg_printk("\n");
 804		}
 805		*secure_exec = true;
 806	}
 
 
 
 
 
 
 
 
 
 
 
 
 807
 808audit:
 809	return aa_audit_file(profile, &perms, OP_EXEC, AA_MAY_ONEXEC, xname,
 810			     NULL, onexec, cond->uid, info, error);
 811}
 812
 813/* ensure none ns domain transitions are correctly applied with onexec */
 
 
 814
 815static struct aa_label *handle_onexec(struct aa_label *label,
 816				      struct aa_label *onexec, bool stack,
 817				      const struct linux_binprm *bprm,
 818				      char *buffer, struct path_cond *cond,
 819				      bool *unsafe)
 820{
 821	struct aa_profile *profile;
 822	struct aa_label *new;
 823	int error;
 824
 825	AA_BUG(!label);
 826	AA_BUG(!onexec);
 827	AA_BUG(!bprm);
 828	AA_BUG(!buffer);
 829
 830	if (!stack) {
 831		error = fn_for_each_in_ns(label, profile,
 832				profile_onexec(profile, onexec, stack,
 833					       bprm, buffer, cond, unsafe));
 834		if (error)
 835			return ERR_PTR(error);
 836		new = fn_label_build_in_ns(label, profile, GFP_ATOMIC,
 837				aa_get_newest_label(onexec),
 838				profile_transition(profile, bprm, buffer,
 839						   cond, unsafe));
 840
 841	} else {
 842		/* TODO: determine how much we want to losen this */
 843		error = fn_for_each_in_ns(label, profile,
 844				profile_onexec(profile, onexec, stack, bprm,
 845					       buffer, cond, unsafe));
 846		if (error)
 847			return ERR_PTR(error);
 848		new = fn_label_build_in_ns(label, profile, GFP_ATOMIC,
 849				aa_label_merge(&profile->label, onexec,
 850					       GFP_ATOMIC),
 851				profile_transition(profile, bprm, buffer,
 852						   cond, unsafe));
 853	}
 854
 855	if (new)
 856		return new;
 857
 858	/* TODO: get rid of GLOBAL_ROOT_UID */
 859	error = fn_for_each_in_ns(label, profile,
 860			aa_audit_file(profile, &nullperms, OP_CHANGE_ONEXEC,
 861				      AA_MAY_ONEXEC, bprm->filename, NULL,
 862				      onexec, GLOBAL_ROOT_UID,
 863				      "failed to build target label", -ENOMEM));
 864	return ERR_PTR(error);
 865}
 866
 867/**
 868 * apparmor_bprm_set_creds - set the new creds on the bprm struct
 869 * @bprm: binprm for the exec  (NOT NULL)
 870 *
 871 * Returns: %0 or error on failure
 872 *
 873 * TODO: once the other paths are done see if we can't refactor into a fn
 874 */
 875int apparmor_bprm_set_creds(struct linux_binprm *bprm)
 876{
 877	struct aa_task_ctx *ctx;
 878	struct aa_label *label, *new = NULL;
 879	struct aa_profile *profile;
 880	char *buffer = NULL;
 881	const char *info = NULL;
 882	int error = 0;
 883	bool unsafe = false;
 884	struct path_cond cond = {
 885		file_inode(bprm->file)->i_uid,
 886		file_inode(bprm->file)->i_mode
 887	};
 888
 889	if (bprm->called_set_creds)
 890		return 0;
 891
 892	ctx = task_ctx(current);
 893	AA_BUG(!cred_label(bprm->cred));
 894	AA_BUG(!ctx);
 895
 896	label = aa_get_newest_label(cred_label(bprm->cred));
 897
 898	/*
 899	 * Detect no new privs being set, and store the label it
 900	 * occurred under. Ideally this would happen when nnp
 901	 * is set but there isn't a good way to do that yet.
 902	 *
 903	 * Testing for unconfined must be done before the subset test
 904	 */
 905	if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) && !unconfined(label) &&
 906	    !ctx->nnp)
 907		ctx->nnp = aa_get_label(label);
 908
 909	/* buffer freed below, name is pointer into buffer */
 910	get_buffers(buffer);
 911	/* Test for onexec first as onexec override other x transitions. */
 912	if (ctx->onexec)
 913		new = handle_onexec(label, ctx->onexec, ctx->token,
 914				    bprm, buffer, &cond, &unsafe);
 915	else
 916		new = fn_label_build(label, profile, GFP_ATOMIC,
 917				profile_transition(profile, bprm, buffer,
 918						   &cond, &unsafe));
 919
 920	AA_BUG(!new);
 921	if (IS_ERR(new)) {
 922		error = PTR_ERR(new);
 923		goto done;
 924	} else if (!new) {
 925		error = -ENOMEM;
 926		goto done;
 927	}
 928
 929	/* Policy has specified a domain transitions. If no_new_privs and
 930	 * confined ensure the transition is to confinement that is subset
 931	 * of the confinement when the task entered no new privs.
 932	 *
 933	 * NOTE: Domain transitions from unconfined and to stacked
 934	 * subsets are allowed even when no_new_privs is set because this
 935	 * aways results in a further reduction of permissions.
 936	 */
 937	if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) &&
 938	    !unconfined(label) && !aa_label_is_subset(new, ctx->nnp)) {
 939		error = -EPERM;
 940		info = "no new privs";
 941		goto audit;
 942	}
 943
 944	if (bprm->unsafe & LSM_UNSAFE_SHARE) {
 945		/* FIXME: currently don't mediate shared state */
 946		;
 947	}
 948
 949	if (bprm->unsafe & (LSM_UNSAFE_PTRACE)) {
 950		/* TODO: test needs to be profile of label to new */
 951		error = may_change_ptraced_domain(new, &info);
 952		if (error)
 953			goto audit;
 954	}
 955
 956	if (unsafe) {
 957		if (DEBUG_ON) {
 958			dbg_printk("scrubbing environment variables for %s "
 959				   "label=", bprm->filename);
 960			aa_label_printk(new, GFP_ATOMIC);
 961			dbg_printk("\n");
 962		}
 963		bprm->secureexec = 1;
 964	}
 965
 966	if (label->proxy != new->proxy) {
 967		/* when transitioning clear unsafe personality bits */
 968		if (DEBUG_ON) {
 969			dbg_printk("apparmor: clearing unsafe personality "
 970				   "bits. %s label=", bprm->filename);
 971			aa_label_printk(new, GFP_ATOMIC);
 972			dbg_printk("\n");
 973		}
 974		bprm->per_clear |= PER_CLEAR_ON_SETID;
 975	}
 976	aa_put_label(cred_label(bprm->cred));
 977	/* transfer reference, released when cred is freed */
 978	cred_label(bprm->cred) = new;
 979
 980done:
 981	aa_put_label(label);
 982	put_buffers(buffer);
 983
 984	return error;
 985
 986audit:
 987	error = fn_for_each(label, profile,
 988			aa_audit_file(profile, &nullperms, OP_EXEC, MAY_EXEC,
 989				      bprm->filename, NULL, new,
 990				      file_inode(bprm->file)->i_uid, info,
 991				      error));
 992	aa_put_label(new);
 993	goto done;
 994}
 995
 996/*
 997 * Functions for self directed profile change
 998 */
 999
1000
1001/* helper fn for change_hat
1002 *
1003 * Returns: label for hat transition OR ERR_PTR.  Does NOT return NULL
1004 */
1005static struct aa_label *build_change_hat(struct aa_profile *profile,
1006					 const char *name, bool sibling)
1007{
1008	struct aa_profile *root, *hat = NULL;
1009	const char *info = NULL;
1010	int error = 0;
1011
1012	if (sibling && PROFILE_IS_HAT(profile)) {
1013		root = aa_get_profile_rcu(&profile->parent);
1014	} else if (!sibling && !PROFILE_IS_HAT(profile)) {
1015		root = aa_get_profile(profile);
1016	} else {
1017		info = "conflicting target types";
1018		error = -EPERM;
1019		goto audit;
1020	}
1021
1022	hat = aa_find_child(root, name);
1023	if (!hat) {
1024		error = -ENOENT;
1025		if (COMPLAIN_MODE(profile)) {
1026			hat = aa_new_null_profile(profile, true, name,
1027						  GFP_KERNEL);
1028			if (!hat) {
1029				info = "failed null profile create";
1030				error = -ENOMEM;
1031			}
1032		}
1033	}
1034	aa_put_profile(root);
1035
1036audit:
1037	aa_audit_file(profile, &nullperms, OP_CHANGE_HAT, AA_MAY_CHANGEHAT,
1038		      name, hat ? hat->base.hname : NULL,
1039		      hat ? &hat->label : NULL, GLOBAL_ROOT_UID, NULL,
1040		      error);
1041	if (!hat || (error && error != -ENOENT))
1042		return ERR_PTR(error);
1043	/* if hat && error - complain mode, already audited and we adjust for
1044	 * complain mode allow by returning hat->label
1045	 */
1046	return &hat->label;
1047}
1048
1049/* helper fn for changing into a hat
1050 *
1051 * Returns: label for hat transition or ERR_PTR. Does not return NULL
1052 */
1053static struct aa_label *change_hat(struct aa_label *label, const char *hats[],
1054				   int count, int flags)
1055{
1056	struct aa_profile *profile, *root, *hat = NULL;
1057	struct aa_label *new;
1058	struct label_it it;
1059	bool sibling = false;
1060	const char *name, *info = NULL;
1061	int i, error;
1062
1063	AA_BUG(!label);
1064	AA_BUG(!hats);
1065	AA_BUG(count < 1);
1066
1067	if (PROFILE_IS_HAT(labels_profile(label)))
1068		sibling = true;
1069
1070	/*find first matching hat */
1071	for (i = 0; i < count && !hat; i++) {
1072		name = hats[i];
1073		label_for_each_in_ns(it, labels_ns(label), label, profile) {
1074			if (sibling && PROFILE_IS_HAT(profile)) {
1075				root = aa_get_profile_rcu(&profile->parent);
1076			} else if (!sibling && !PROFILE_IS_HAT(profile)) {
1077				root = aa_get_profile(profile);
1078			} else {	/* conflicting change type */
1079				info = "conflicting targets types";
1080				error = -EPERM;
1081				goto fail;
1082			}
1083			hat = aa_find_child(root, name);
1084			aa_put_profile(root);
1085			if (!hat) {
1086				if (!COMPLAIN_MODE(profile))
1087					goto outer_continue;
1088				/* complain mode succeed as if hat */
1089			} else if (!PROFILE_IS_HAT(hat)) {
1090				info = "target not hat";
1091				error = -EPERM;
1092				aa_put_profile(hat);
1093				goto fail;
1094			}
1095			aa_put_profile(hat);
1096		}
1097		/* found a hat for all profiles in ns */
1098		goto build;
1099outer_continue:
1100	;
1101	}
1102	/* no hats that match, find appropriate error
1103	 *
1104	 * In complain mode audit of the failure is based off of the first
1105	 * hat supplied.  This is done due how userspace interacts with
1106	 * change_hat.
1107	 */
1108	name = NULL;
1109	label_for_each_in_ns(it, labels_ns(label), label, profile) {
1110		if (!list_empty(&profile->base.profiles)) {
1111			info = "hat not found";
1112			error = -ENOENT;
1113			goto fail;
1114		}
1115	}
1116	info = "no hats defined";
1117	error = -ECHILD;
1118
1119fail:
1120	label_for_each_in_ns(it, labels_ns(label), label, profile) {
1121		/*
1122		 * no target as it has failed to be found or built
1123		 *
1124		 * change_hat uses probing and should not log failures
1125		 * related to missing hats
1126		 */
1127		/* TODO: get rid of GLOBAL_ROOT_UID */
1128		if (count > 1 || COMPLAIN_MODE(profile)) {
1129			aa_audit_file(profile, &nullperms, OP_CHANGE_HAT,
1130				      AA_MAY_CHANGEHAT, name, NULL, NULL,
1131				      GLOBAL_ROOT_UID, info, error);
1132		}
1133	}
1134	return ERR_PTR(error);
1135
1136build:
1137	new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
1138				   build_change_hat(profile, name, sibling),
1139				   aa_get_label(&profile->label));
1140	if (!new) {
1141		info = "label build failed";
1142		error = -ENOMEM;
1143		goto fail;
1144	} /* else if (IS_ERR) build_change_hat has logged error so return new */
1145
1146	return new;
 
 
 
 
 
 
 
 
 
 
 
 
1147}
1148
1149/**
1150 * aa_change_hat - change hat to/from subprofile
1151 * @hats: vector of hat names to try changing into (MAYBE NULL if @count == 0)
1152 * @count: number of hat names in @hats
1153 * @token: magic value to validate the hat change
1154 * @flags: flags affecting behavior of the change
1155 *
1156 * Returns %0 on success, error otherwise.
1157 *
1158 * Change to the first profile specified in @hats that exists, and store
1159 * the @hat_magic in the current task context.  If the count == 0 and the
1160 * @token matches that stored in the current task context, return to the
1161 * top level profile.
1162 *
1163 * change_hat only applies to profiles in the current ns, and each profile
1164 * in the ns must make the same transition otherwise change_hat will fail.
1165 */
1166int aa_change_hat(const char *hats[], int count, u64 token, int flags)
1167{
1168	const struct cred *cred;
1169	struct aa_task_ctx *ctx = task_ctx(current);
1170	struct aa_label *label, *previous, *new = NULL, *target = NULL;
1171	struct aa_profile *profile;
1172	struct aa_perms perms = {};
1173	const char *info = NULL;
 
1174	int error = 0;
1175
1176	/* released below */
1177	cred = get_current_cred();
1178	label = aa_get_newest_cred_label(cred);
1179	previous = aa_get_newest_label(ctx->previous);
1180
1181	/*
1182	 * Detect no new privs being set, and store the label it
1183	 * occurred under. Ideally this would happen when nnp
1184	 * is set but there isn't a good way to do that yet.
1185	 *
1186	 * Testing for unconfined must be done before the subset test
1187	 */
1188	if (task_no_new_privs(current) && !unconfined(label) && !ctx->nnp)
1189		ctx->nnp = aa_get_label(label);
 
 
 
 
 
 
1190
1191	if (unconfined(label)) {
1192		info = "unconfined can not change_hat";
1193		error = -EPERM;
1194		goto fail;
1195	}
1196
1197	if (count) {
1198		new = change_hat(label, hats, count, flags);
1199		AA_BUG(!new);
1200		if (IS_ERR(new)) {
1201			error = PTR_ERR(new);
1202			new = NULL;
1203			/* already audited */
1204			goto out;
1205		}
 
 
 
 
 
 
 
 
1206
1207		error = may_change_ptraced_domain(new, &info);
1208		if (error)
1209			goto fail;
 
 
 
 
 
1210
1211		/*
1212		 * no new privs prevents domain transitions that would
1213		 * reduce restrictions.
1214		 */
1215		if (task_no_new_privs(current) && !unconfined(label) &&
1216		    !aa_label_is_subset(new, ctx->nnp)) {
1217			/* not an apparmor denial per se, so don't log it */
1218			AA_DEBUG("no_new_privs - change_hat denied");
1219			error = -EPERM;
1220			goto out;
 
 
 
 
 
 
 
1221		}
1222
1223		if (flags & AA_CHANGE_TEST)
1224			goto out;
1225
1226		target = new;
1227		error = aa_set_current_hat(new, token);
1228		if (error == -EACCES)
1229			/* kill task in case of brute force attacks */
1230			goto kill;
1231	} else if (previous && !(flags & AA_CHANGE_TEST)) {
1232		/*
1233		 * no new privs prevents domain transitions that would
1234		 * reduce restrictions.
1235		 */
1236		if (task_no_new_privs(current) && !unconfined(label) &&
1237		    !aa_label_is_subset(previous, ctx->nnp)) {
1238			/* not an apparmor denial per se, so don't log it */
1239			AA_DEBUG("no_new_privs - change_hat denied");
1240			error = -EPERM;
1241			goto out;
1242		}
1243
1244		/* Return to saved label.  Kill task if restore fails
1245		 * to avoid brute force attacks
1246		 */
1247		target = previous;
1248		error = aa_restore_previous_label(token);
1249		if (error) {
1250			if (error == -EACCES)
1251				goto kill;
1252			goto fail;
 
 
 
1253		}
1254	} /* else ignore @flags && restores when there is no saved profile */
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1255
1256out:
1257	aa_put_label(new);
1258	aa_put_label(previous);
1259	aa_put_label(label);
1260	put_cred(cred);
1261
1262	return error;
1263
1264kill:
1265	info = "failed token match";
1266	perms.kill = AA_MAY_CHANGEHAT;
1267
1268fail:
1269	fn_for_each_in_ns(label, profile,
1270		aa_audit_file(profile, &perms, OP_CHANGE_HAT,
1271			      AA_MAY_CHANGEHAT, NULL, NULL, target,
1272			      GLOBAL_ROOT_UID, info, error));
1273
1274	goto out;
1275}
1276
1277
1278static int change_profile_perms_wrapper(const char *op, const char *name,
1279					struct aa_profile *profile,
1280					struct aa_label *target, bool stack,
1281					u32 request, struct aa_perms *perms)
1282{
1283	const char *info = NULL;
1284	int error = 0;
1285
1286	if (!error)
1287		error = change_profile_perms(profile, target, stack, request,
1288					     profile->file.start, perms);
1289	if (error)
1290		error = aa_audit_file(profile, perms, op, request, name,
1291				      NULL, target, GLOBAL_ROOT_UID, info,
1292				      error);
1293
1294	return error;
1295}
1296
1297/**
1298 * aa_change_profile - perform a one-way profile transition
1299 * @fqname: name of profile may include namespace (NOT NULL)
 
1300 * @onexec: whether this transition is to take place immediately or at exec
1301 * @flags: flags affecting change behavior
1302 *
1303 * Change to new profile @name.  Unlike with hats, there is no way
1304 * to change back.  If @name isn't specified the current profile name is
1305 * used.
1306 * If @onexec then the transition is delayed until
1307 * the next exec.
1308 *
1309 * Returns %0 on success, error otherwise.
1310 */
1311int aa_change_profile(const char *fqname, int flags)
 
1312{
1313	struct aa_label *label, *new = NULL, *target = NULL;
1314	struct aa_profile *profile;
1315	struct aa_perms perms = {};
1316	const char *info = NULL;
1317	const char *auditname = fqname;		/* retain leading & if stack */
1318	bool stack = flags & AA_CHANGE_STACK;
1319	struct aa_task_ctx *ctx = task_ctx(current);
1320	int error = 0;
1321	char *op;
1322	u32 request;
1323
1324	label = aa_get_current_label();
1325
1326	/*
1327	 * Detect no new privs being set, and store the label it
1328	 * occurred under. Ideally this would happen when nnp
1329	 * is set but there isn't a good way to do that yet.
1330	 *
1331	 * Testing for unconfined must be done before the subset test
1332	 */
1333	if (task_no_new_privs(current) && !unconfined(label) && !ctx->nnp)
1334		ctx->nnp = aa_get_label(label);
1335
1336	if (!fqname || !*fqname) {
1337		AA_DEBUG("no profile name");
1338		return -EINVAL;
1339	}
1340
1341	if (flags & AA_CHANGE_ONEXEC) {
1342		request = AA_MAY_ONEXEC;
1343		if (stack)
1344			op = OP_STACK_ONEXEC;
1345		else
1346			op = OP_CHANGE_ONEXEC;
1347	} else {
1348		request = AA_MAY_CHANGE_PROFILE;
1349		if (stack)
1350			op = OP_STACK;
1351		else
1352			op = OP_CHANGE_PROFILE;
1353	}
1354
1355	label = aa_get_current_label();
 
 
1356
1357	if (*fqname == '&') {
1358		stack = true;
1359		/* don't have label_parse() do stacking */
1360		fqname++;
 
 
 
 
 
 
1361	}
1362	target = aa_label_parse(label, fqname, GFP_KERNEL, true, false);
1363	if (IS_ERR(target)) {
1364		struct aa_profile *tprofile;
1365
1366		info = "label not found";
1367		error = PTR_ERR(target);
1368		target = NULL;
1369		/*
1370		 * TODO: fixme using labels_profile is not right - do profile
1371		 * per complain profile
1372		 */
1373		if ((flags & AA_CHANGE_TEST) ||
1374		    !COMPLAIN_MODE(labels_profile(label)))
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1375			goto audit;
1376		/* released below */
1377		tprofile = aa_new_null_profile(labels_profile(label), false,
1378					       fqname, GFP_KERNEL);
1379		if (!tprofile) {
1380			info = "failed null profile create";
1381			error = -ENOMEM;
1382			goto audit;
1383		}
1384		target = &tprofile->label;
1385		goto check;
1386	}
1387
1388	/*
1389	 * self directed transitions only apply to current policy ns
1390	 * TODO: currently requiring perms for stacking and straight change
1391	 *       stacking doesn't strictly need this. Determine how much
1392	 *       we want to loosen this restriction for stacking
1393	 *
1394	 * if (!stack) {
1395	 */
1396	error = fn_for_each_in_ns(label, profile,
1397			change_profile_perms_wrapper(op, auditname,
1398						     profile, target, stack,
1399						     request, &perms));
1400	if (error)
1401		/* auditing done in change_profile_perms_wrapper */
1402		goto out;
1403
1404	/* } */
1405
1406check:
1407	/* check if tracing task is allowed to trace target domain */
1408	error = may_change_ptraced_domain(target, &info);
1409	if (error && !fn_for_each_in_ns(label, profile,
1410					COMPLAIN_MODE(profile)))
1411		goto audit;
1412
1413	/* TODO: add permission check to allow this
1414	 * if ((flags & AA_CHANGE_ONEXEC) && !current_is_single_threaded()) {
1415	 *      info = "not a single threaded task";
1416	 *      error = -EACCES;
1417	 *      goto audit;
1418	 * }
1419	 */
1420	if (flags & AA_CHANGE_TEST)
1421		goto out;
1422
1423	/* stacking is always a subset, so only check the nonstack case */
1424	if (!stack) {
1425		new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
1426					   aa_get_label(target),
1427					   aa_get_label(&profile->label));
1428		/*
1429		 * no new privs prevents domain transitions that would
1430		 * reduce restrictions.
1431		 */
1432		if (task_no_new_privs(current) && !unconfined(label) &&
1433		    !aa_label_is_subset(new, ctx->nnp)) {
1434			/* not an apparmor denial per se, so don't log it */
1435			AA_DEBUG("no_new_privs - change_hat denied");
1436			error = -EPERM;
1437			goto out;
1438		}
1439	}
1440
1441	if (!(flags & AA_CHANGE_ONEXEC)) {
1442		/* only transition profiles in the current ns */
1443		if (stack)
1444			new = aa_label_merge(label, target, GFP_KERNEL);
1445		if (IS_ERR_OR_NULL(new)) {
1446			info = "failed to build target label";
1447			error = PTR_ERR(new);
1448			new = NULL;
1449			perms.allow = 0;
1450			goto audit;
1451		}
1452		error = aa_replace_current_label(new);
1453	} else {
1454		if (new) {
1455			aa_put_label(new);
1456			new = NULL;
1457		}
1458
1459		/* full transition will be built in exec path */
1460		error = aa_set_current_onexec(target, stack);
1461	}
 
1462
1463audit:
1464	error = fn_for_each_in_ns(label, profile,
1465			aa_audit_file(profile, &perms, op, request, auditname,
1466				      NULL, new ? new : target,
1467				      GLOBAL_ROOT_UID, info, error));
1468
1469out:
1470	aa_put_label(new);
1471	aa_put_label(target);
1472	aa_put_label(label);
1473
1474	return error;
1475}
v3.5.6
  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 */
 37void 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 */
 61static int may_change_ptraced_domain(struct task_struct *task,
 62				     struct aa_profile *to_profile)
 63{
 64	struct task_struct *tracer;
 65	const struct cred *cred = NULL;
 66	struct aa_profile *tracerp = NULL;
 67	int error = 0;
 68
 69	rcu_read_lock();
 70	tracer = ptrace_parent(task);
 71	if (tracer) {
 72		/* released below */
 73		cred = get_task_cred(tracer);
 74		tracerp = aa_cred_profile(cred);
 75	}
 76
 77	/* not ptraced */
 78	if (!tracer || unconfined(tracerp))
 79		goto out;
 80
 81	error = aa_may_ptrace(tracer, tracerp, to_profile, PTRACE_MODE_ATTACH);
 82
 83out:
 84	rcu_read_unlock();
 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 */
101static 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 */
145static 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 */
179static 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 */
212static 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
233static 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 */
245static 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 */
306static 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 */
343int 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_path_name(&bprm->file->f_path, profile->path_flags, &buffer,
376			     &name, &info);
377	if (error) {
378		if (profile->flags &
379		    (PFLAG_IX_ON_NAME_ERROR | PFLAG_UNCONFINED))
 
380			error = 0;
 
 
381		name = bprm->filename;
382		goto audit;
383	}
384
385	/* Test for onexec first as onexec directives override other
386	 * x transitions.
387	 */
388	if (unconfined(profile)) {
389		/* unconfined task */
390		if (cxt->onexec)
391			/* change_profile on exec already been granted */
392			new_profile = aa_get_profile(cxt->onexec);
393		else
394			new_profile = find_attach(ns, &ns->base.profiles, name);
395		if (!new_profile)
396			goto cleanup;
397		/*
398		 * NOTE: Domain transitions from unconfined are allowed
399		 * even when no_new_privs is set because this aways results
400		 * in a further reduction of permissions.
401		 */
402		goto apply;
403	}
404
405	/* find exec permissions for name */
406	state = aa_str_perms(profile->file.dfa, state, name, &cond, &perms);
407	if (cxt->onexec) {
408		struct file_perms cp;
409		info = "change_profile onexec";
410		if (!(perms.allow & AA_MAY_ONEXEC))
411			goto audit;
412
413		/* test if this exec can be paired with change_profile onexec.
414		 * onexec permission is linked to exec with a standard pairing
415		 * exec\0change_profile
416		 */
417		state = aa_dfa_null_transition(profile->file.dfa, state);
418		cp = change_profile_perms(profile, cxt->onexec->ns,
419					  cxt->onexec->base.name,
420					  AA_MAY_ONEXEC, state);
421
422		if (!(cp.allow & AA_MAY_ONEXEC))
423			goto audit;
424		new_profile = aa_get_profile(aa_newest_version(cxt->onexec));
425		goto apply;
426	}
427
428	if (perms.allow & MAY_EXEC) {
429		/* exec permission determine how to transition */
430		new_profile = x_to_profile(profile, name, perms.xindex);
431		if (!new_profile) {
432			if (perms.xindex & AA_X_INHERIT) {
433				/* (p|c|n)ix - don't change profile but do
434				 * use the newest version, which was picked
435				 * up above when getting profile
436				 */
437				info = "ix fallback";
438				new_profile = aa_get_profile(profile);
439				goto x_clear;
440			} else if (perms.xindex & AA_X_UNCONFINED) {
441				new_profile = aa_get_profile(ns->unconfined);
442				info = "ux fallback";
443			} else {
444				error = -ENOENT;
445				info = "profile not found";
 
 
 
 
 
 
 
 
446			}
447		}
448	} else if (COMPLAIN_MODE(profile)) {
449		/* no exec permission - are we in learning mode */
450		new_profile = aa_new_null_profile(profile, 0);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
451		if (!new_profile) {
452			error = -ENOMEM;
453			info = "could not create null profile";
454		} else {
455			error = -EACCES;
456			target = new_profile->base.hname;
457		}
458		perms.xindex |= AA_X_UNSAFE;
459	} else
460		/* fail exec */
461		error = -EACCES;
462
463	/*
464	 * Policy has specified a domain transition, if no_new_privs then
465	 * fail the exec.
466	 */
467	if (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) {
468		aa_put_profile(new_profile);
469		error = -EPERM;
470		goto cleanup;
 
 
 
 
 
 
 
 
 
 
 
 
471	}
472
473	if (!new_profile)
474		goto audit;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
475
476	if (bprm->unsafe & LSM_UNSAFE_SHARE) {
477		/* FIXME: currently don't mediate shared state */
478		;
 
 
 
 
 
479	}
480
481	if (bprm->unsafe & (LSM_UNSAFE_PTRACE | LSM_UNSAFE_PTRACE_CAP)) {
482		error = may_change_ptraced_domain(current, new_profile);
483		if (error) {
484			aa_put_profile(new_profile);
485			goto audit;
 
 
486		}
 
 
487	}
488
489	/* Determine if secure exec is needed.
490	 * Can be at this point for the following reasons:
491	 * 1. unconfined switching to confined
492	 * 2. confined switching to different confinement
493	 * 3. confined switching to unconfined
494	 *
495	 * Cases 2 and 3 are marked as requiring secure exec
496	 * (unless policy specified "unsafe exec")
497	 *
498	 * bprm->unsafe is used to cache the AA_X_UNSAFE permission
499	 * to avoid having to recompute in secureexec
500	 */
 
 
 
 
 
 
 
 
501	if (!(perms.xindex & AA_X_UNSAFE)) {
502		AA_DEBUG("scrubbing environment variables for %s profile=%s\n",
503			 name, new_profile->base.hname);
504		bprm->unsafe |= AA_SECURE_X_NEEDED;
505	}
506apply:
507	target = new_profile->base.hname;
508	/* when transitioning profiles clear unsafe personality bits */
509	bprm->per_clear |= PER_CLEAR_ON_SETID;
510
511x_clear:
512	aa_put_profile(cxt->profile);
513	/* transfer new profile reference will be released when cxt is freed */
514	cxt->profile = new_profile;
515
516	/* clear out all temporary/transitional state from the context */
517	aa_put_profile(cxt->previous);
518	aa_put_profile(cxt->onexec);
519	cxt->previous = NULL;
520	cxt->onexec = NULL;
521	cxt->token = 0;
522
523audit:
524	error = aa_audit_file(profile, &perms, GFP_KERNEL, OP_EXEC, MAY_EXEC,
525			      name, target, cond.uid, info, error);
 
526
527cleanup:
528	aa_put_profile(profile);
529	kfree(buffer);
530
531	return error;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
532}
533
534/**
535 * apparmor_bprm_secureexec - determine if secureexec is needed
536 * @bprm: binprm for exec  (NOT NULL)
 
 
537 *
538 * Returns: %1 if secureexec is needed else %0
539 */
540int apparmor_bprm_secureexec(struct linux_binprm *bprm)
541{
542	int ret = cap_bprm_secureexec(bprm);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
543
544	/* the decision to use secure exec is computed in set_creds
545	 * and stored in bprm->unsafe.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
546	 */
547	if (!ret && (bprm->unsafe & AA_SECURE_X_NEEDED))
548		ret = 1;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
549
550	return ret;
 
 
 
 
 
 
 
551}
552
553/**
554 * apparmor_bprm_committing_creds - do task cleanup on committing new creds
555 * @bprm: binprm for the exec  (NOT NULL)
 
 
 
 
 
556 */
557void apparmor_bprm_committing_creds(struct linux_binprm *bprm)
 
558{
559	struct aa_profile *profile = __aa_current_profile();
560	struct aa_task_cxt *new_cxt = bprm->cred->security;
 
561
562	/* bail out if unconfined or not changing profile */
563	if ((new_cxt->profile == profile) ||
564	    (unconfined(new_cxt->profile)))
565		return;
 
 
 
 
 
566
567	current->pdeath_signal = 0;
 
 
 
 
 
 
 
 
 
 
 
 
568
569	/* reset soft limits and set hard limits for the new profile */
570	__aa_transition_rlimits(profile, new_cxt->profile);
 
 
 
 
 
 
 
 
 
571}
572
573/**
574 * apparmor_bprm_commited_cred - do cleanup after new creds committed
575 * @bprm: binprm for the exec  (NOT NULL)
576 */
577void apparmor_bprm_committed_creds(struct linux_binprm *bprm)
 
578{
579	/* TODO: cleanup signals - ipc mediation */
580	return;
581}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
582
583/*
584 * Functions for self directed profile change
585 */
 
 
 
 
 
 
586
587/**
588 * new_compound_name - create an hname with @n2 appended to @n1
589 * @n1: base of hname  (NOT NULL)
590 * @n2: name to append (NOT NULL)
591 *
592 * Returns: new name or NULL on error
593 */
594static char *new_compound_name(const char *n1, const char *n2)
595{
596	char *name = kmalloc(strlen(n1) + strlen(n2) + 3, GFP_KERNEL);
597	if (name)
598		sprintf(name, "%s//%s", n1, n2);
599	return name;
600}
601
602/**
603 * aa_change_hat - change hat to/from subprofile
604 * @hats: vector of hat names to try changing into (MAYBE NULL if @count == 0)
605 * @count: number of hat names in @hats
606 * @token: magic value to validate the hat change
607 * @permtest: true if this is just a permission test
 
 
608 *
609 * Change to the first profile specified in @hats that exists, and store
610 * the @hat_magic in the current task context.  If the count == 0 and the
611 * @token matches that stored in the current task context, return to the
612 * top level profile.
613 *
614 * Returns %0 on success, error otherwise.
 
615 */
616int aa_change_hat(const char *hats[], int count, u64 token, bool permtest)
617{
618	const struct cred *cred;
619	struct aa_task_cxt *cxt;
620	struct aa_profile *profile, *previous_profile, *hat = NULL;
621	char *name = NULL;
622	int i;
623	struct file_perms perms = {};
624	const char *target = NULL, *info = NULL;
625	int error = 0;
626
 
 
 
 
 
627	/*
628	 * Fail explicitly requested domain transitions if no_new_privs.
629	 * There is no exception for unconfined as change_hat is not
630	 * available.
 
 
631	 */
632	if (current->no_new_privs)
633		return -EPERM;
634
635	/* released below */
636	cred = get_current_cred();
637	cxt = cred->security;
638	profile = aa_cred_profile(cred);
639	previous_profile = cxt->previous;
640
641	if (unconfined(profile)) {
642		info = "unconfined";
643		error = -EPERM;
644		goto audit;
645	}
646
647	if (count) {
648		/* attempting to change into a new hat or switch to a sibling */
649		struct aa_profile *root;
650		root = PROFILE_IS_HAT(profile) ? profile->parent : profile;
651
652		/* find first matching hat */
653		for (i = 0; i < count && !hat; i++)
654			/* released below */
655			hat = aa_find_child(root, hats[i]);
656		if (!hat) {
657			if (!COMPLAIN_MODE(root) || permtest) {
658				if (list_empty(&root->base.profiles))
659					error = -ECHILD;
660				else
661					error = -ENOENT;
662				goto out;
663			}
664
665			/*
666			 * In complain mode and failed to match any hats.
667			 * Audit the failure is based off of the first hat
668			 * supplied.  This is done due how userspace
669			 * interacts with change_hat.
670			 *
671			 * TODO: Add logging of all failed hats
672			 */
673
674			/* freed below */
675			name = new_compound_name(root->base.hname, hats[0]);
676			target = name;
677			/* released below */
678			hat = aa_new_null_profile(profile, 1);
679			if (!hat) {
680				info = "failed null profile create";
681				error = -ENOMEM;
682				goto audit;
683			}
684		} else {
685			target = hat->base.hname;
686			if (!PROFILE_IS_HAT(hat)) {
687				info = "target not hat";
688				error = -EPERM;
689				goto audit;
690			}
691		}
692
693		error = may_change_ptraced_domain(current, hat);
694		if (error) {
695			info = "ptraced";
 
 
 
 
 
 
 
 
 
 
 
 
 
 
696			error = -EPERM;
697			goto audit;
698		}
699
700		if (!permtest) {
701			error = aa_set_current_hat(hat, token);
 
 
 
 
702			if (error == -EACCES)
703				/* kill task in case of brute force attacks */
704				perms.kill = AA_MAY_CHANGEHAT;
705			else if (name && !error)
706				/* reset error for learning of new hats */
707				error = -ENOENT;
708		}
709	} else if (previous_profile) {
710		/* Return to saved profile.  Kill task if restore fails
711		 * to avoid brute force attacks
712		 */
713		target = previous_profile->base.hname;
714		error = aa_restore_previous_profile(token);
715		perms.kill = AA_MAY_CHANGEHAT;
716	} else
717		/* ignore restores when there is no saved profile */
718		goto out;
719
720audit:
721	if (!permtest)
722		error = aa_audit_file(profile, &perms, GFP_KERNEL,
723				      OP_CHANGE_HAT, AA_MAY_CHANGEHAT, NULL,
724				      target, 0, info, error);
725
726out:
727	aa_put_profile(hat);
728	kfree(name);
 
729	put_cred(cred);
730
731	return error;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
732}
733
734/**
735 * aa_change_profile - perform a one-way profile transition
736 * @ns_name: name of the profile namespace to change to (MAYBE NULL)
737 * @hname: name of profile to change to (MAYBE NULL)
738 * @onexec: whether this transition is to take place immediately or at exec
739 * @permtest: true if this is just a permission test
740 *
741 * Change to new profile @name.  Unlike with hats, there is no way
742 * to change back.  If @name isn't specified the current profile name is
743 * used.
744 * If @onexec then the transition is delayed until
745 * the next exec.
746 *
747 * Returns %0 on success, error otherwise.
748 */
749int aa_change_profile(const char *ns_name, const char *hname, bool onexec,
750		      bool permtest)
751{
752	const struct cred *cred;
753	struct aa_task_cxt *cxt;
754	struct aa_profile *profile, *target = NULL;
755	struct aa_namespace *ns = NULL;
756	struct file_perms perms = {};
757	const char *name = NULL, *info = NULL;
758	int op, error = 0;
 
 
759	u32 request;
760
761	if (!hname && !ns_name)
 
 
 
 
 
 
 
 
 
 
 
 
 
762		return -EINVAL;
 
763
764	if (onexec) {
765		request = AA_MAY_ONEXEC;
766		op = OP_CHANGE_ONEXEC;
 
 
 
767	} else {
768		request = AA_MAY_CHANGE_PROFILE;
769		op = OP_CHANGE_PROFILE;
 
 
 
770	}
771
772	cred = get_current_cred();
773	cxt = cred->security;
774	profile = aa_cred_profile(cred);
775
776	/*
777	 * Fail explicitly requested domain transitions if no_new_privs
778	 * and not unconfined.
779	 * Domain transitions from unconfined are allowed even when
780	 * no_new_privs is set because this aways results in a reduction
781	 * of permissions.
782	 */
783	if (current->no_new_privs && !unconfined(profile)) {
784		put_cred(cred);
785		return -EPERM;
786	}
 
 
 
787
788	if (ns_name) {
789		/* released below */
790		ns = aa_find_namespace(profile->ns, ns_name);
791		if (!ns) {
792			/* we don't create new namespace in complain mode */
793			name = ns_name;
794			info = "namespace not found";
795			error = -ENOENT;
796			goto audit;
797		}
798	} else
799		/* released below */
800		ns = aa_get_namespace(profile->ns);
801
802	/* if the name was not specified, use the name of the current profile */
803	if (!hname) {
804		if (unconfined(profile))
805			hname = ns->unconfined->base.hname;
806		else
807			hname = profile->base.hname;
808	}
809
810	perms = change_profile_perms(profile, ns, hname, request,
811				     profile->file.start);
812	if (!(perms.allow & request)) {
813		error = -EACCES;
814		goto audit;
815	}
816
817	/* released below */
818	target = aa_lookup_profile(ns, hname);
819	if (!target) {
820		info = "profile not found";
821		error = -ENOENT;
822		if (permtest || !COMPLAIN_MODE(profile))
823			goto audit;
824		/* released below */
825		target = aa_new_null_profile(profile, 0);
826		if (!target) {
 
827			info = "failed null profile create";
828			error = -ENOMEM;
829			goto audit;
830		}
 
 
831	}
832
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
833	/* check if tracing task is allowed to trace target domain */
834	error = may_change_ptraced_domain(current, target);
835	if (error) {
836		info = "ptrace prevents transition";
837		goto audit;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
838	}
839
840	if (permtest)
841		goto audit;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
842
843	if (onexec)
844		error = aa_set_current_onexec(target);
845	else
846		error = aa_replace_current_profile(target);
847
848audit:
849	if (!permtest)
850		error = aa_audit_file(profile, &perms, GFP_KERNEL, op, request,
851				      name, hname, 0, info, error);
 
852
853	aa_put_namespace(ns);
854	aa_put_profile(target);
855	put_cred(cred);
 
856
857	return error;
858}