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v5.4
   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * AppArmor security module
   4 *
   5 * This file contains AppArmor policy attachment and domain transitions
   6 *
   7 * Copyright (C) 2002-2008 Novell/SUSE
   8 * Copyright 2009-2010 Canonical Ltd.
 
 
 
 
 
   9 */
  10
  11#include <linux/errno.h>
  12#include <linux/fdtable.h>
  13#include <linux/file.h>
  14#include <linux/mount.h>
  15#include <linux/syscalls.h>
  16#include <linux/tracehook.h>
  17#include <linux/personality.h>
  18#include <linux/xattr.h>
  19
  20#include "include/audit.h"
  21#include "include/apparmorfs.h"
  22#include "include/cred.h"
  23#include "include/domain.h"
  24#include "include/file.h"
  25#include "include/ipc.h"
  26#include "include/match.h"
  27#include "include/path.h"
  28#include "include/policy.h"
  29#include "include/policy_ns.h"
  30
  31/**
  32 * aa_free_domain_entries - free entries in a domain table
  33 * @domain: the domain table to free  (MAYBE NULL)
  34 */
  35void aa_free_domain_entries(struct aa_domain *domain)
  36{
  37	int i;
  38	if (domain) {
  39		if (!domain->table)
  40			return;
  41
  42		for (i = 0; i < domain->size; i++)
  43			kzfree(domain->table[i]);
  44		kzfree(domain->table);
  45		domain->table = NULL;
  46	}
  47}
  48
  49/**
  50 * may_change_ptraced_domain - check if can change profile on ptraced task
  51 * @to_label: profile to change to  (NOT NULL)
  52 * @info: message if there is an error
  53 *
  54 * Check if current is ptraced and if so if the tracing task is allowed
  55 * to trace the new domain
  56 *
  57 * Returns: %0 or error if change not allowed
  58 */
  59static int may_change_ptraced_domain(struct aa_label *to_label,
  60				     const char **info)
  61{
  62	struct task_struct *tracer;
  63	struct aa_label *tracerl = NULL;
 
  64	int error = 0;
  65
  66	rcu_read_lock();
  67	tracer = ptrace_parent(current);
  68	if (tracer)
  69		/* released below */
  70		tracerl = aa_get_task_label(tracer);
 
 
  71
  72	/* not ptraced */
  73	if (!tracer || unconfined(tracerl))
  74		goto out;
  75
  76	error = aa_may_ptrace(tracerl, to_label, PTRACE_MODE_ATTACH);
  77
  78out:
  79	rcu_read_unlock();
  80	aa_put_label(tracerl);
 
  81
  82	if (error)
  83		*info = "ptrace prevents transition";
  84	return error;
  85}
  86
  87/**** TODO: dedup to aa_label_match - needs perm and dfa, merging
  88 * specifically this is an exact copy of aa_label_match except
  89 * aa_compute_perms is replaced with aa_compute_fperms
  90 * and policy.dfa with file.dfa
  91 ****/
  92/* match a profile and its associated ns component if needed
  93 * Assumes visibility test has already been done.
  94 * If a subns profile is not to be matched should be prescreened with
  95 * visibility test.
  96 */
  97static inline unsigned int match_component(struct aa_profile *profile,
  98					   struct aa_profile *tp,
  99					   bool stack, unsigned int state)
 100{
 101	const char *ns_name;
 102
 103	if (stack)
 104		state = aa_dfa_match(profile->file.dfa, state, "&");
 105	if (profile->ns == tp->ns)
 106		return aa_dfa_match(profile->file.dfa, state, tp->base.hname);
 107
 108	/* try matching with namespace name and then profile */
 109	ns_name = aa_ns_name(profile->ns, tp->ns, true);
 110	state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
 111	state = aa_dfa_match(profile->file.dfa, state, ns_name);
 112	state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
 113	return aa_dfa_match(profile->file.dfa, state, tp->base.hname);
 114}
 115
 116/**
 117 * label_compound_match - find perms for full compound label
 118 * @profile: profile to find perms for
 119 * @label: label to check access permissions for
 120 * @stack: whether this is a stacking request
 121 * @start: state to start match in
 122 * @subns: whether to do permission checks on components in a subns
 123 * @request: permissions to request
 124 * @perms: perms struct to set
 125 *
 126 * Returns: 0 on success else ERROR
 127 *
 128 * For the label A//&B//&C this does the perm match for A//&B//&C
 129 * @perms should be preinitialized with allperms OR a previous permission
 130 *        check to be stacked.
 131 */
 132static int label_compound_match(struct aa_profile *profile,
 133				struct aa_label *label, bool stack,
 134				unsigned int state, bool subns, u32 request,
 135				struct aa_perms *perms)
 136{
 137	struct aa_profile *tp;
 138	struct label_it i;
 139	struct path_cond cond = { };
 140
 141	/* find first subcomponent that is visible */
 142	label_for_each(i, label, tp) {
 143		if (!aa_ns_visible(profile->ns, tp->ns, subns))
 144			continue;
 145		state = match_component(profile, tp, stack, state);
 146		if (!state)
 147			goto fail;
 148		goto next;
 149	}
 150
 151	/* no component visible */
 152	*perms = allperms;
 153	return 0;
 154
 155next:
 156	label_for_each_cont(i, label, tp) {
 157		if (!aa_ns_visible(profile->ns, tp->ns, subns))
 158			continue;
 159		state = aa_dfa_match(profile->file.dfa, state, "//&");
 160		state = match_component(profile, tp, false, state);
 161		if (!state)
 162			goto fail;
 163	}
 164	*perms = aa_compute_fperms(profile->file.dfa, state, &cond);
 165	aa_apply_modes_to_perms(profile, perms);
 166	if ((perms->allow & request) != request)
 167		return -EACCES;
 168
 169	return 0;
 170
 171fail:
 172	*perms = nullperms;
 173	return -EACCES;
 174}
 175
 176/**
 177 * label_components_match - find perms for all subcomponents of a label
 178 * @profile: profile to find perms for
 179 * @label: label to check access permissions for
 180 * @stack: whether this is a stacking request
 181 * @start: state to start match in
 182 * @subns: whether to do permission checks on components in a subns
 183 * @request: permissions to request
 184 * @perms: an initialized perms struct to add accumulation to
 185 *
 186 * Returns: 0 on success else ERROR
 187 *
 188 * For the label A//&B//&C this does the perm match for each of A and B and C
 189 * @perms should be preinitialized with allperms OR a previous permission
 190 *        check to be stacked.
 191 */
 192static int label_components_match(struct aa_profile *profile,
 193				  struct aa_label *label, bool stack,
 194				  unsigned int start, bool subns, u32 request,
 195				  struct aa_perms *perms)
 196{
 197	struct aa_profile *tp;
 198	struct label_it i;
 199	struct aa_perms tmp;
 200	struct path_cond cond = { };
 201	unsigned int state = 0;
 202
 203	/* find first subcomponent to test */
 204	label_for_each(i, label, tp) {
 205		if (!aa_ns_visible(profile->ns, tp->ns, subns))
 206			continue;
 207		state = match_component(profile, tp, stack, start);
 208		if (!state)
 209			goto fail;
 210		goto next;
 211	}
 212
 213	/* no subcomponents visible - no change in perms */
 214	return 0;
 215
 216next:
 217	tmp = aa_compute_fperms(profile->file.dfa, state, &cond);
 218	aa_apply_modes_to_perms(profile, &tmp);
 219	aa_perms_accum(perms, &tmp);
 220	label_for_each_cont(i, label, tp) {
 221		if (!aa_ns_visible(profile->ns, tp->ns, subns))
 222			continue;
 223		state = match_component(profile, tp, stack, start);
 224		if (!state)
 225			goto fail;
 226		tmp = aa_compute_fperms(profile->file.dfa, state, &cond);
 227		aa_apply_modes_to_perms(profile, &tmp);
 228		aa_perms_accum(perms, &tmp);
 229	}
 230
 231	if ((perms->allow & request) != request)
 232		return -EACCES;
 233
 234	return 0;
 235
 236fail:
 237	*perms = nullperms;
 238	return -EACCES;
 239}
 240
 241/**
 242 * label_match - do a multi-component label match
 243 * @profile: profile to match against (NOT NULL)
 244 * @label: label to match (NOT NULL)
 245 * @stack: whether this is a stacking request
 246 * @state: state to start in
 247 * @subns: whether to match subns components
 248 * @request: permission request
 249 * @perms: Returns computed perms (NOT NULL)
 250 *
 251 * Returns: the state the match finished in, may be the none matching state
 252 */
 253static int label_match(struct aa_profile *profile, struct aa_label *label,
 254		       bool stack, unsigned int state, bool subns, u32 request,
 255		       struct aa_perms *perms)
 256{
 257	int error;
 258
 259	*perms = nullperms;
 260	error = label_compound_match(profile, label, stack, state, subns,
 261				     request, perms);
 262	if (!error)
 263		return error;
 264
 265	*perms = allperms;
 266	return label_components_match(profile, label, stack, state, subns,
 267				      request, perms);
 268}
 269
 270/******* end TODO: dedup *****/
 271
 272/**
 273 * change_profile_perms - find permissions for change_profile
 274 * @profile: the current profile  (NOT NULL)
 275 * @target: label to transition to (NOT NULL)
 276 * @stack: whether this is a stacking request
 277 * @request: requested perms
 278 * @start: state to start matching in
 279 *
 280 *
 281 * Returns: permission set
 282 *
 283 * currently only matches full label A//&B//&C or individual components A, B, C
 284 * not arbitrary combinations. Eg. A//&B, C
 285 */
 286static int change_profile_perms(struct aa_profile *profile,
 287				struct aa_label *target, bool stack,
 288				u32 request, unsigned int start,
 289				struct aa_perms *perms)
 290{
 291	if (profile_unconfined(profile)) {
 292		perms->allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC;
 293		perms->audit = perms->quiet = perms->kill = 0;
 294		return 0;
 295	}
 296
 297	/* TODO: add profile in ns screening */
 298	return label_match(profile, target, stack, start, true, request, perms);
 299}
 300
 301/**
 302 * aa_xattrs_match - check whether a file matches the xattrs defined in profile
 303 * @bprm: binprm struct for the process to validate
 304 * @profile: profile to match against (NOT NULL)
 305 * @state: state to start match in
 306 *
 307 * Returns: number of extended attributes that matched, or < 0 on error
 308 */
 309static int aa_xattrs_match(const struct linux_binprm *bprm,
 310			   struct aa_profile *profile, unsigned int state)
 
 
 311{
 312	int i;
 313	ssize_t size;
 314	struct dentry *d;
 315	char *value = NULL;
 316	int value_size = 0, ret = profile->xattr_count;
 317
 318	if (!bprm || !profile->xattr_count)
 319		return 0;
 320
 321	/* transition from exec match to xattr set */
 322	state = aa_dfa_null_transition(profile->xmatch, state);
 323
 324	d = bprm->file->f_path.dentry;
 325
 326	for (i = 0; i < profile->xattr_count; i++) {
 327		size = vfs_getxattr_alloc(d, profile->xattrs[i], &value,
 328					  value_size, GFP_KERNEL);
 329		if (size >= 0) {
 330			u32 perm;
 331
 332			/* Check the xattr value, not just presence */
 333			state = aa_dfa_match_len(profile->xmatch, state, value,
 334						 size);
 335			perm = dfa_user_allow(profile->xmatch, state);
 336			if (!(perm & MAY_EXEC)) {
 337				ret = -EINVAL;
 338				goto out;
 339			}
 340		}
 341		/* transition to next element */
 342		state = aa_dfa_null_transition(profile->xmatch, state);
 343		if (size < 0) {
 344			/*
 345			 * No xattr match, so verify if transition to
 346			 * next element was valid. IFF so the xattr
 347			 * was optional.
 348			 */
 349			if (!state) {
 350				ret = -EINVAL;
 351				goto out;
 352			}
 353			/* don't count missing optional xattr as matched */
 354			ret--;
 355		}
 356	}
 357
 358out:
 359	kfree(value);
 360	return ret;
 
 
 
 361}
 362
 363/**
 364 * __attach_match_ - find an attachment match
 365 * @bprm - binprm structure of transitioning task
 366 * @name - to match against  (NOT NULL)
 367 * @head - profile list to walk  (NOT NULL)
 368 * @info - info message if there was an error (NOT NULL)
 369 *
 370 * Do a linear search on the profiles in the list.  There is a matching
 371 * preference where an exact match is preferred over a name which uses
 372 * expressions to match, and matching expressions with the greatest
 373 * xmatch_len are preferred.
 374 *
 375 * Requires: @head not be shared or have appropriate locks held
 376 *
 377 * Returns: profile or NULL if no match found
 378 */
 379static struct aa_profile *__attach_match(const struct linux_binprm *bprm,
 380					 const char *name,
 381					 struct list_head *head,
 382					 const char **info)
 383{
 384	int candidate_len = 0, candidate_xattrs = 0;
 385	bool conflict = false;
 386	struct aa_profile *profile, *candidate = NULL;
 387
 388	AA_BUG(!name);
 389	AA_BUG(!head);
 390
 391	list_for_each_entry_rcu(profile, head, base.list) {
 392		if (profile->label.flags & FLAG_NULL &&
 393		    &profile->label == ns_unconfined(profile->ns))
 394			continue;
 395
 396		/* Find the "best" matching profile. Profiles must
 397		 * match the path and extended attributes (if any)
 398		 * associated with the file. A more specific path
 399		 * match will be preferred over a less specific one,
 400		 * and a match with more matching extended attributes
 401		 * will be preferred over one with fewer. If the best
 402		 * match has both the same level of path specificity
 403		 * and the same number of matching extended attributes
 404		 * as another profile, signal a conflict and refuse to
 405		 * match.
 406		 */
 407		if (profile->xmatch) {
 408			unsigned int state, count;
 409			u32 perm;
 410
 411			state = aa_dfa_leftmatch(profile->xmatch, DFA_START,
 412						 name, &count);
 413			perm = dfa_user_allow(profile->xmatch, state);
 414			/* any accepting state means a valid match. */
 415			if (perm & MAY_EXEC) {
 416				int ret;
 417
 418				if (count < candidate_len)
 419					continue;
 420
 421				ret = aa_xattrs_match(bprm, profile, state);
 422				/* Fail matching if the xattrs don't match */
 423				if (ret < 0)
 424					continue;
 425
 426				/*
 427				 * TODO: allow for more flexible best match
 428				 *
 429				 * The new match isn't more specific
 430				 * than the current best match
 431				 */
 432				if (count == candidate_len &&
 433				    ret <= candidate_xattrs) {
 434					/* Match is equivalent, so conflict */
 435					if (ret == candidate_xattrs)
 436						conflict = true;
 437					continue;
 438				}
 439
 440				/* Either the same length with more matching
 441				 * xattrs, or a longer match
 442				 */
 443				candidate = profile;
 444				candidate_len = profile->xmatch_len;
 445				candidate_xattrs = ret;
 446				conflict = false;
 447			}
 448		} else if (!strcmp(profile->base.name, name))
 449			/*
 450			 * old exact non-re match, without conditionals such
 451			 * as xattrs. no more searching required
 452			 */
 453			return profile;
 454	}
 455
 456	if (conflict) {
 457		*info = "conflicting profile attachments";
 458		return NULL;
 459	}
 460
 461	return candidate;
 462}
 463
 464/**
 465 * find_attach - do attachment search for unconfined processes
 466 * @bprm - binprm structure of transitioning task
 467 * @ns: the current namespace  (NOT NULL)
 468 * @list: list to search  (NOT NULL)
 469 * @name: the executable name to match against  (NOT NULL)
 470 * @info: info message if there was an error
 471 *
 472 * Returns: label or NULL if no match found
 473 */
 474static struct aa_label *find_attach(const struct linux_binprm *bprm,
 475				    struct aa_ns *ns, struct list_head *list,
 476				    const char *name, const char **info)
 477{
 478	struct aa_profile *profile;
 479
 480	rcu_read_lock();
 481	profile = aa_get_profile(__attach_match(bprm, name, list, info));
 482	rcu_read_unlock();
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 483
 484	return profile ? &profile->label : NULL;
 485}
 486
 487static const char *next_name(int xtype, const char *name)
 488{
 489	return NULL;
 490}
 491
 492/**
 493 * x_table_lookup - lookup an x transition name via transition table
 494 * @profile: current profile (NOT NULL)
 495 * @xindex: index into x transition table
 496 * @name: returns: name tested to find label (NOT NULL)
 497 *
 498 * Returns: refcounted label, or NULL on failure (MAYBE NULL)
 499 */
 500struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
 501				const char **name)
 502{
 503	struct aa_label *label = NULL;
 
 504	u32 xtype = xindex & AA_X_TYPE_MASK;
 505	int index = xindex & AA_X_INDEX_MASK;
 506
 507	AA_BUG(!name);
 508
 509	/* index is guaranteed to be in range, validated at load time */
 510	/* TODO: move lookup parsing to unpack time so this is a straight
 511	 *       index into the resultant label
 512	 */
 513	for (*name = profile->file.trans.table[index]; !label && *name;
 514	     *name = next_name(xtype, *name)) {
 
 515		if (xindex & AA_X_CHILD) {
 516			struct aa_profile *new_profile;
 517			/* release by caller */
 518			new_profile = aa_find_child(profile, *name);
 519			if (new_profile)
 520				label = &new_profile->label;
 521			continue;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 522		}
 523		label = aa_label_parse(&profile->label, *name, GFP_ATOMIC,
 524				       true, false);
 525		if (IS_ERR(label))
 526			label = NULL;
 527	}
 528
 529	/* released by caller */
 530
 531	return label;
 532}
 533
 534/**
 535 * x_to_label - get target label for a given xindex
 536 * @profile: current profile  (NOT NULL)
 537 * @bprm: binprm structure of transitioning task
 538 * @name: name to lookup (NOT NULL)
 539 * @xindex: index into x transition table
 540 * @lookupname: returns: name used in lookup if one was specified (NOT NULL)
 541 *
 542 * find label for a transition index
 543 *
 544 * Returns: refcounted label or NULL if not found available
 545 */
 546static struct aa_label *x_to_label(struct aa_profile *profile,
 547				   const struct linux_binprm *bprm,
 548				   const char *name, u32 xindex,
 549				   const char **lookupname,
 550				   const char **info)
 551{
 552	struct aa_label *new = NULL;
 553	struct aa_ns *ns = profile->ns;
 554	u32 xtype = xindex & AA_X_TYPE_MASK;
 555	const char *stack = NULL;
 556
 557	switch (xtype) {
 558	case AA_X_NONE:
 559		/* fail exec unless ix || ux fallback - handled by caller */
 560		*lookupname = NULL;
 561		break;
 562	case AA_X_TABLE:
 563		/* TODO: fix when perm mapping done at unload */
 564		stack = profile->file.trans.table[xindex & AA_X_INDEX_MASK];
 565		if (*stack != '&') {
 566			/* released by caller */
 567			new = x_table_lookup(profile, xindex, lookupname);
 568			stack = NULL;
 569			break;
 570		}
 571		/* fall through - to X_NAME */
 572	case AA_X_NAME:
 573		if (xindex & AA_X_CHILD)
 574			/* released by caller */
 575			new = find_attach(bprm, ns, &profile->base.profiles,
 576					  name, info);
 577		else
 578			/* released by caller */
 579			new = find_attach(bprm, ns, &ns->base.profiles,
 580					  name, info);
 581		*lookupname = name;
 
 
 
 582		break;
 583	}
 584
 585	if (!new) {
 586		if (xindex & AA_X_INHERIT) {
 587			/* (p|c|n)ix - don't change profile but do
 588			 * use the newest version
 589			 */
 590			*info = "ix fallback";
 591			/* no profile && no error */
 592			new = aa_get_newest_label(&profile->label);
 593		} else if (xindex & AA_X_UNCONFINED) {
 594			new = aa_get_newest_label(ns_unconfined(profile->ns));
 595			*info = "ux fallback";
 596		}
 597	}
 598
 599	if (new && stack) {
 600		/* base the stack on post domain transition */
 601		struct aa_label *base = new;
 602
 603		new = aa_label_parse(base, stack, GFP_ATOMIC, true, false);
 604		if (IS_ERR(new))
 605			new = NULL;
 606		aa_put_label(base);
 607	}
 608
 609	/* released by caller */
 610	return new;
 611}
 612
 613static struct aa_label *profile_transition(struct aa_profile *profile,
 614					   const struct linux_binprm *bprm,
 615					   char *buffer, struct path_cond *cond,
 616					   bool *secure_exec)
 
 
 
 617{
 618	struct aa_label *new = NULL;
 619	struct aa_profile *component;
 620	struct label_it i;
 621	const char *info = NULL, *name = NULL, *target = NULL;
 622	unsigned int state = profile->file.start;
 623	struct aa_perms perms = {};
 624	bool nonewprivs = false;
 625	int error = 0;
 
 
 
 
 
 
 
 
 
 626
 627	AA_BUG(!profile);
 628	AA_BUG(!bprm);
 629	AA_BUG(!buffer);
 
 
 
 
 
 
 
 630
 631	error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
 632			     &name, &info, profile->disconnected);
 
 633	if (error) {
 634		if (profile_unconfined(profile) ||
 635		    (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
 636			AA_DEBUG("name lookup ix on error");
 637			error = 0;
 638			new = aa_get_newest_label(&profile->label);
 639		}
 640		name = bprm->filename;
 641		goto audit;
 642	}
 643
 644	if (profile_unconfined(profile)) {
 645		new = find_attach(bprm, profile->ns,
 646				  &profile->ns->base.profiles, name, &info);
 647		if (new) {
 648			AA_DEBUG("unconfined attached to new label");
 649			return new;
 650		}
 651		AA_DEBUG("unconfined exec no attachment");
 652		return aa_get_newest_label(&profile->label);
 
 
 
 
 
 
 
 
 
 653	}
 654
 655	/* find exec permissions for name */
 656	state = aa_str_perms(profile->file.dfa, state, name, cond, &perms);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 657	if (perms.allow & MAY_EXEC) {
 658		/* exec permission determine how to transition */
 659		new = x_to_label(profile, bprm, name, perms.xindex, &target,
 660				 &info);
 661		if (new && new->proxy == profile->label.proxy && info) {
 662			/* hack ix fallback - improve how this is detected */
 663			goto audit;
 664		} else if (!new) {
 665			error = -EACCES;
 666			info = "profile transition not found";
 667			/* remove MAY_EXEC to audit as failure */
 668			perms.allow &= ~MAY_EXEC;
 669		} else {
 670			/* verify that each component's xattr requirements are
 671			 * met, and fail execution otherwise
 672			 */
 673			label_for_each(i, new, component) {
 674				if (aa_xattrs_match(bprm, component, state) <
 675				    0) {
 676					error = -EACCES;
 677					info = "required xattrs not present";
 678					perms.allow &= ~MAY_EXEC;
 679					aa_put_label(new);
 680					new = NULL;
 681					goto audit;
 682				}
 683			}
 684		}
 685	} else if (COMPLAIN_MODE(profile)) {
 686		/* no exec permission - learning mode */
 687		struct aa_profile *new_profile = NULL;
 688		char *n = kstrdup(name, GFP_ATOMIC);
 689
 690		if (n) {
 691			/* name is ptr into buffer */
 692			long pos = name - buffer;
 693			/* break per cpu buffer hold */
 694			put_buffers(buffer);
 695			new_profile = aa_new_null_profile(profile, false, n,
 696							  GFP_KERNEL);
 697			get_buffers(buffer);
 698			name = buffer + pos;
 699			strcpy((char *)name, n);
 700			kfree(n);
 701		}
 702		if (!new_profile) {
 703			error = -ENOMEM;
 704			info = "could not create null profile";
 705		} else {
 706			error = -EACCES;
 707			new = &new_profile->label;
 708		}
 709		perms.xindex |= AA_X_UNSAFE;
 710	} else
 711		/* fail exec */
 712		error = -EACCES;
 713
 714	if (!new)
 715		goto audit;
 716
 717
 718	if (!(perms.xindex & AA_X_UNSAFE)) {
 719		if (DEBUG_ON) {
 720			dbg_printk("apparmor: scrubbing environment variables"
 721				   " for %s profile=", name);
 722			aa_label_printk(new, GFP_ATOMIC);
 723			dbg_printk("\n");
 724		}
 725		*secure_exec = true;
 726	}
 727
 728audit:
 729	aa_audit_file(profile, &perms, OP_EXEC, MAY_EXEC, name, target, new,
 730		      cond->uid, info, error);
 731	if (!new || nonewprivs) {
 732		aa_put_label(new);
 733		return ERR_PTR(error);
 734	}
 735
 736	return new;
 737}
 738
 739static int profile_onexec(struct aa_profile *profile, struct aa_label *onexec,
 740			  bool stack, const struct linux_binprm *bprm,
 741			  char *buffer, struct path_cond *cond,
 742			  bool *secure_exec)
 743{
 744	unsigned int state = profile->file.start;
 745	struct aa_perms perms = {};
 746	const char *xname = NULL, *info = "change_profile onexec";
 747	int error = -EACCES;
 748
 749	AA_BUG(!profile);
 750	AA_BUG(!onexec);
 751	AA_BUG(!bprm);
 752	AA_BUG(!buffer);
 753
 754	if (profile_unconfined(profile)) {
 755		/* change_profile on exec already granted */
 756		/*
 757		 * NOTE: Domain transitions from unconfined are allowed
 758		 * even when no_new_privs is set because this aways results
 759		 * in a further reduction of permissions.
 760		 */
 761		return 0;
 762	}
 763
 764	error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
 765			     &xname, &info, profile->disconnected);
 766	if (error) {
 767		if (profile_unconfined(profile) ||
 768		    (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
 769			AA_DEBUG("name lookup ix on error");
 770			error = 0;
 771		}
 772		xname = bprm->filename;
 773		goto audit;
 774	}
 775
 776	/* find exec permissions for name */
 777	state = aa_str_perms(profile->file.dfa, state, xname, cond, &perms);
 778	if (!(perms.allow & AA_MAY_ONEXEC)) {
 779		info = "no change_onexec valid for executable";
 780		goto audit;
 781	}
 782	/* test if this exec can be paired with change_profile onexec.
 783	 * onexec permission is linked to exec with a standard pairing
 784	 * exec\0change_profile
 
 
 785	 */
 786	state = aa_dfa_null_transition(profile->file.dfa, state);
 787	error = change_profile_perms(profile, onexec, stack, AA_MAY_ONEXEC,
 788				     state, &perms);
 789	if (error) {
 790		perms.allow &= ~AA_MAY_ONEXEC;
 791		goto audit;
 792	}
 793
 794	if (!(perms.xindex & AA_X_UNSAFE)) {
 795		if (DEBUG_ON) {
 796			dbg_printk("apparmor: scrubbing environment "
 797				   "variables for %s label=", xname);
 798			aa_label_printk(onexec, GFP_ATOMIC);
 799			dbg_printk("\n");
 800		}
 801		*secure_exec = true;
 802	}
 
 
 
 
 
 
 
 
 
 
 
 
 803
 804audit:
 805	return aa_audit_file(profile, &perms, OP_EXEC, AA_MAY_ONEXEC, xname,
 806			     NULL, onexec, cond->uid, info, error);
 807}
 808
 809/* ensure none ns domain transitions are correctly applied with onexec */
 
 
 810
 811static struct aa_label *handle_onexec(struct aa_label *label,
 812				      struct aa_label *onexec, bool stack,
 813				      const struct linux_binprm *bprm,
 814				      char *buffer, struct path_cond *cond,
 815				      bool *unsafe)
 816{
 817	struct aa_profile *profile;
 818	struct aa_label *new;
 819	int error;
 820
 821	AA_BUG(!label);
 822	AA_BUG(!onexec);
 823	AA_BUG(!bprm);
 824	AA_BUG(!buffer);
 825
 826	if (!stack) {
 827		error = fn_for_each_in_ns(label, profile,
 828				profile_onexec(profile, onexec, stack,
 829					       bprm, buffer, cond, unsafe));
 830		if (error)
 831			return ERR_PTR(error);
 832		new = fn_label_build_in_ns(label, profile, GFP_ATOMIC,
 833				aa_get_newest_label(onexec),
 834				profile_transition(profile, bprm, buffer,
 835						   cond, unsafe));
 836
 837	} else {
 838		/* TODO: determine how much we want to loosen this */
 839		error = fn_for_each_in_ns(label, profile,
 840				profile_onexec(profile, onexec, stack, bprm,
 841					       buffer, cond, unsafe));
 842		if (error)
 843			return ERR_PTR(error);
 844		new = fn_label_build_in_ns(label, profile, GFP_ATOMIC,
 845				aa_label_merge(&profile->label, onexec,
 846					       GFP_ATOMIC),
 847				profile_transition(profile, bprm, buffer,
 848						   cond, unsafe));
 849	}
 850
 851	if (new)
 852		return new;
 853
 854	/* TODO: get rid of GLOBAL_ROOT_UID */
 855	error = fn_for_each_in_ns(label, profile,
 856			aa_audit_file(profile, &nullperms, OP_CHANGE_ONEXEC,
 857				      AA_MAY_ONEXEC, bprm->filename, NULL,
 858				      onexec, GLOBAL_ROOT_UID,
 859				      "failed to build target label", -ENOMEM));
 860	return ERR_PTR(error);
 861}
 862
 863/**
 864 * apparmor_bprm_set_creds - set the new creds on the bprm struct
 865 * @bprm: binprm for the exec  (NOT NULL)
 866 *
 867 * Returns: %0 or error on failure
 868 *
 869 * TODO: once the other paths are done see if we can't refactor into a fn
 870 */
 871int apparmor_bprm_set_creds(struct linux_binprm *bprm)
 872{
 873	struct aa_task_ctx *ctx;
 874	struct aa_label *label, *new = NULL;
 875	struct aa_profile *profile;
 876	char *buffer = NULL;
 877	const char *info = NULL;
 878	int error = 0;
 879	bool unsafe = false;
 880	struct path_cond cond = {
 881		file_inode(bprm->file)->i_uid,
 882		file_inode(bprm->file)->i_mode
 883	};
 884
 885	if (bprm->called_set_creds)
 886		return 0;
 887
 888	ctx = task_ctx(current);
 889	AA_BUG(!cred_label(bprm->cred));
 890	AA_BUG(!ctx);
 891
 892	label = aa_get_newest_label(cred_label(bprm->cred));
 893
 894	/*
 895	 * Detect no new privs being set, and store the label it
 896	 * occurred under. Ideally this would happen when nnp
 897	 * is set but there isn't a good way to do that yet.
 898	 *
 899	 * Testing for unconfined must be done before the subset test
 900	 */
 901	if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) && !unconfined(label) &&
 902	    !ctx->nnp)
 903		ctx->nnp = aa_get_label(label);
 904
 905	/* buffer freed below, name is pointer into buffer */
 906	get_buffers(buffer);
 907	/* Test for onexec first as onexec override other x transitions. */
 908	if (ctx->onexec)
 909		new = handle_onexec(label, ctx->onexec, ctx->token,
 910				    bprm, buffer, &cond, &unsafe);
 911	else
 912		new = fn_label_build(label, profile, GFP_ATOMIC,
 913				profile_transition(profile, bprm, buffer,
 914						   &cond, &unsafe));
 915
 916	AA_BUG(!new);
 917	if (IS_ERR(new)) {
 918		error = PTR_ERR(new);
 919		goto done;
 920	} else if (!new) {
 921		error = -ENOMEM;
 922		goto done;
 923	}
 924
 925	/* Policy has specified a domain transitions. If no_new_privs and
 926	 * confined ensure the transition is to confinement that is subset
 927	 * of the confinement when the task entered no new privs.
 928	 *
 929	 * NOTE: Domain transitions from unconfined and to stacked
 930	 * subsets are allowed even when no_new_privs is set because this
 931	 * aways results in a further reduction of permissions.
 932	 */
 933	if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) &&
 934	    !unconfined(label) && !aa_label_is_subset(new, ctx->nnp)) {
 935		error = -EPERM;
 936		info = "no new privs";
 937		goto audit;
 938	}
 939
 940	if (bprm->unsafe & LSM_UNSAFE_SHARE) {
 941		/* FIXME: currently don't mediate shared state */
 942		;
 943	}
 944
 945	if (bprm->unsafe & (LSM_UNSAFE_PTRACE)) {
 946		/* TODO: test needs to be profile of label to new */
 947		error = may_change_ptraced_domain(new, &info);
 948		if (error)
 949			goto audit;
 950	}
 951
 952	if (unsafe) {
 953		if (DEBUG_ON) {
 954			dbg_printk("scrubbing environment variables for %s "
 955				   "label=", bprm->filename);
 956			aa_label_printk(new, GFP_ATOMIC);
 957			dbg_printk("\n");
 958		}
 959		bprm->secureexec = 1;
 960	}
 961
 962	if (label->proxy != new->proxy) {
 963		/* when transitioning clear unsafe personality bits */
 964		if (DEBUG_ON) {
 965			dbg_printk("apparmor: clearing unsafe personality "
 966				   "bits. %s label=", bprm->filename);
 967			aa_label_printk(new, GFP_ATOMIC);
 968			dbg_printk("\n");
 969		}
 970		bprm->per_clear |= PER_CLEAR_ON_SETID;
 971	}
 972	aa_put_label(cred_label(bprm->cred));
 973	/* transfer reference, released when cred is freed */
 974	set_cred_label(bprm->cred, new);
 975
 976done:
 977	aa_put_label(label);
 978	put_buffers(buffer);
 979
 980	return error;
 981
 982audit:
 983	error = fn_for_each(label, profile,
 984			aa_audit_file(profile, &nullperms, OP_EXEC, MAY_EXEC,
 985				      bprm->filename, NULL, new,
 986				      file_inode(bprm->file)->i_uid, info,
 987				      error));
 988	aa_put_label(new);
 989	goto done;
 990}
 991
 992/*
 993 * Functions for self directed profile change
 994 */
 995
 996
 997/* helper fn for change_hat
 998 *
 999 * Returns: label for hat transition OR ERR_PTR.  Does NOT return NULL
1000 */
1001static struct aa_label *build_change_hat(struct aa_profile *profile,
1002					 const char *name, bool sibling)
1003{
1004	struct aa_profile *root, *hat = NULL;
1005	const char *info = NULL;
1006	int error = 0;
1007
1008	if (sibling && PROFILE_IS_HAT(profile)) {
1009		root = aa_get_profile_rcu(&profile->parent);
1010	} else if (!sibling && !PROFILE_IS_HAT(profile)) {
1011		root = aa_get_profile(profile);
1012	} else {
1013		info = "conflicting target types";
1014		error = -EPERM;
1015		goto audit;
1016	}
1017
1018	hat = aa_find_child(root, name);
1019	if (!hat) {
1020		error = -ENOENT;
1021		if (COMPLAIN_MODE(profile)) {
1022			hat = aa_new_null_profile(profile, true, name,
1023						  GFP_KERNEL);
1024			if (!hat) {
1025				info = "failed null profile create";
1026				error = -ENOMEM;
1027			}
1028		}
1029	}
1030	aa_put_profile(root);
1031
1032audit:
1033	aa_audit_file(profile, &nullperms, OP_CHANGE_HAT, AA_MAY_CHANGEHAT,
1034		      name, hat ? hat->base.hname : NULL,
1035		      hat ? &hat->label : NULL, GLOBAL_ROOT_UID, info,
1036		      error);
1037	if (!hat || (error && error != -ENOENT))
1038		return ERR_PTR(error);
1039	/* if hat && error - complain mode, already audited and we adjust for
1040	 * complain mode allow by returning hat->label
1041	 */
1042	return &hat->label;
1043}
1044
1045/* helper fn for changing into a hat
1046 *
1047 * Returns: label for hat transition or ERR_PTR. Does not return NULL
1048 */
1049static struct aa_label *change_hat(struct aa_label *label, const char *hats[],
1050				   int count, int flags)
1051{
1052	struct aa_profile *profile, *root, *hat = NULL;
1053	struct aa_label *new;
1054	struct label_it it;
1055	bool sibling = false;
1056	const char *name, *info = NULL;
1057	int i, error;
1058
1059	AA_BUG(!label);
1060	AA_BUG(!hats);
1061	AA_BUG(count < 1);
1062
1063	if (PROFILE_IS_HAT(labels_profile(label)))
1064		sibling = true;
1065
1066	/*find first matching hat */
1067	for (i = 0; i < count && !hat; i++) {
1068		name = hats[i];
1069		label_for_each_in_ns(it, labels_ns(label), label, profile) {
1070			if (sibling && PROFILE_IS_HAT(profile)) {
1071				root = aa_get_profile_rcu(&profile->parent);
1072			} else if (!sibling && !PROFILE_IS_HAT(profile)) {
1073				root = aa_get_profile(profile);
1074			} else {	/* conflicting change type */
1075				info = "conflicting targets types";
1076				error = -EPERM;
1077				goto fail;
1078			}
1079			hat = aa_find_child(root, name);
1080			aa_put_profile(root);
1081			if (!hat) {
1082				if (!COMPLAIN_MODE(profile))
1083					goto outer_continue;
1084				/* complain mode succeed as if hat */
1085			} else if (!PROFILE_IS_HAT(hat)) {
1086				info = "target not hat";
1087				error = -EPERM;
1088				aa_put_profile(hat);
1089				goto fail;
1090			}
1091			aa_put_profile(hat);
1092		}
1093		/* found a hat for all profiles in ns */
1094		goto build;
1095outer_continue:
1096	;
1097	}
1098	/* no hats that match, find appropriate error
1099	 *
1100	 * In complain mode audit of the failure is based off of the first
1101	 * hat supplied.  This is done due how userspace interacts with
1102	 * change_hat.
1103	 */
1104	name = NULL;
1105	label_for_each_in_ns(it, labels_ns(label), label, profile) {
1106		if (!list_empty(&profile->base.profiles)) {
1107			info = "hat not found";
1108			error = -ENOENT;
1109			goto fail;
1110		}
1111	}
1112	info = "no hats defined";
1113	error = -ECHILD;
1114
1115fail:
1116	label_for_each_in_ns(it, labels_ns(label), label, profile) {
1117		/*
1118		 * no target as it has failed to be found or built
1119		 *
1120		 * change_hat uses probing and should not log failures
1121		 * related to missing hats
1122		 */
1123		/* TODO: get rid of GLOBAL_ROOT_UID */
1124		if (count > 1 || COMPLAIN_MODE(profile)) {
1125			aa_audit_file(profile, &nullperms, OP_CHANGE_HAT,
1126				      AA_MAY_CHANGEHAT, name, NULL, NULL,
1127				      GLOBAL_ROOT_UID, info, error);
1128		}
1129	}
1130	return ERR_PTR(error);
1131
1132build:
1133	new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
1134				   build_change_hat(profile, name, sibling),
1135				   aa_get_label(&profile->label));
1136	if (!new) {
1137		info = "label build failed";
1138		error = -ENOMEM;
1139		goto fail;
1140	} /* else if (IS_ERR) build_change_hat has logged error so return new */
1141
1142	return new;
 
 
 
 
 
 
 
 
 
 
 
 
1143}
1144
1145/**
1146 * aa_change_hat - change hat to/from subprofile
1147 * @hats: vector of hat names to try changing into (MAYBE NULL if @count == 0)
1148 * @count: number of hat names in @hats
1149 * @token: magic value to validate the hat change
1150 * @flags: flags affecting behavior of the change
1151 *
1152 * Returns %0 on success, error otherwise.
1153 *
1154 * Change to the first profile specified in @hats that exists, and store
1155 * the @hat_magic in the current task context.  If the count == 0 and the
1156 * @token matches that stored in the current task context, return to the
1157 * top level profile.
1158 *
1159 * change_hat only applies to profiles in the current ns, and each profile
1160 * in the ns must make the same transition otherwise change_hat will fail.
1161 */
1162int aa_change_hat(const char *hats[], int count, u64 token, int flags)
1163{
1164	const struct cred *cred;
1165	struct aa_task_ctx *ctx = task_ctx(current);
1166	struct aa_label *label, *previous, *new = NULL, *target = NULL;
1167	struct aa_profile *profile;
1168	struct aa_perms perms = {};
1169	const char *info = NULL;
 
1170	int error = 0;
1171
1172	/* released below */
1173	cred = get_current_cred();
1174	label = aa_get_newest_cred_label(cred);
1175	previous = aa_get_newest_label(ctx->previous);
1176
1177	/*
1178	 * Detect no new privs being set, and store the label it
1179	 * occurred under. Ideally this would happen when nnp
1180	 * is set but there isn't a good way to do that yet.
1181	 *
1182	 * Testing for unconfined must be done before the subset test
1183	 */
1184	if (task_no_new_privs(current) && !unconfined(label) && !ctx->nnp)
1185		ctx->nnp = aa_get_label(label);
 
 
 
 
 
 
1186
1187	if (unconfined(label)) {
1188		info = "unconfined can not change_hat";
1189		error = -EPERM;
1190		goto fail;
1191	}
1192
1193	if (count) {
1194		new = change_hat(label, hats, count, flags);
1195		AA_BUG(!new);
1196		if (IS_ERR(new)) {
1197			error = PTR_ERR(new);
1198			new = NULL;
1199			/* already audited */
1200			goto out;
1201		}
 
 
 
 
 
 
 
 
1202
1203		error = may_change_ptraced_domain(new, &info);
1204		if (error)
1205			goto fail;
 
 
 
 
 
1206
1207		/*
1208		 * no new privs prevents domain transitions that would
1209		 * reduce restrictions.
1210		 */
1211		if (task_no_new_privs(current) && !unconfined(label) &&
1212		    !aa_label_is_subset(new, ctx->nnp)) {
1213			/* not an apparmor denial per se, so don't log it */
1214			AA_DEBUG("no_new_privs - change_hat denied");
1215			error = -EPERM;
1216			goto out;
 
 
 
 
 
 
 
1217		}
1218
1219		if (flags & AA_CHANGE_TEST)
1220			goto out;
1221
1222		target = new;
1223		error = aa_set_current_hat(new, token);
1224		if (error == -EACCES)
1225			/* kill task in case of brute force attacks */
1226			goto kill;
1227	} else if (previous && !(flags & AA_CHANGE_TEST)) {
1228		/*
1229		 * no new privs prevents domain transitions that would
1230		 * reduce restrictions.
1231		 */
1232		if (task_no_new_privs(current) && !unconfined(label) &&
1233		    !aa_label_is_subset(previous, ctx->nnp)) {
1234			/* not an apparmor denial per se, so don't log it */
1235			AA_DEBUG("no_new_privs - change_hat denied");
1236			error = -EPERM;
1237			goto out;
1238		}
1239
1240		/* Return to saved label.  Kill task if restore fails
1241		 * to avoid brute force attacks
1242		 */
1243		target = previous;
1244		error = aa_restore_previous_label(token);
1245		if (error) {
1246			if (error == -EACCES)
1247				goto kill;
1248			goto fail;
 
 
 
1249		}
1250	} /* else ignore @flags && restores when there is no saved profile */
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1251
1252out:
1253	aa_put_label(new);
1254	aa_put_label(previous);
1255	aa_put_label(label);
1256	put_cred(cred);
1257
1258	return error;
1259
1260kill:
1261	info = "failed token match";
1262	perms.kill = AA_MAY_CHANGEHAT;
1263
1264fail:
1265	fn_for_each_in_ns(label, profile,
1266		aa_audit_file(profile, &perms, OP_CHANGE_HAT,
1267			      AA_MAY_CHANGEHAT, NULL, NULL, target,
1268			      GLOBAL_ROOT_UID, info, error));
1269
1270	goto out;
1271}
1272
1273
1274static int change_profile_perms_wrapper(const char *op, const char *name,
1275					struct aa_profile *profile,
1276					struct aa_label *target, bool stack,
1277					u32 request, struct aa_perms *perms)
1278{
1279	const char *info = NULL;
1280	int error = 0;
1281
1282	if (!error)
1283		error = change_profile_perms(profile, target, stack, request,
1284					     profile->file.start, perms);
1285	if (error)
1286		error = aa_audit_file(profile, perms, op, request, name,
1287				      NULL, target, GLOBAL_ROOT_UID, info,
1288				      error);
1289
1290	return error;
1291}
1292
1293/**
1294 * aa_change_profile - perform a one-way profile transition
1295 * @fqname: name of profile may include namespace (NOT NULL)
 
1296 * @onexec: whether this transition is to take place immediately or at exec
1297 * @flags: flags affecting change behavior
1298 *
1299 * Change to new profile @name.  Unlike with hats, there is no way
1300 * to change back.  If @name isn't specified the current profile name is
1301 * used.
1302 * If @onexec then the transition is delayed until
1303 * the next exec.
1304 *
1305 * Returns %0 on success, error otherwise.
1306 */
1307int aa_change_profile(const char *fqname, int flags)
 
1308{
1309	struct aa_label *label, *new = NULL, *target = NULL;
1310	struct aa_profile *profile;
1311	struct aa_perms perms = {};
1312	const char *info = NULL;
1313	const char *auditname = fqname;		/* retain leading & if stack */
1314	bool stack = flags & AA_CHANGE_STACK;
1315	struct aa_task_ctx *ctx = task_ctx(current);
1316	int error = 0;
1317	char *op;
1318	u32 request;
1319
1320	label = aa_get_current_label();
1321
1322	/*
1323	 * Detect no new privs being set, and store the label it
1324	 * occurred under. Ideally this would happen when nnp
1325	 * is set but there isn't a good way to do that yet.
1326	 *
1327	 * Testing for unconfined must be done before the subset test
1328	 */
1329	if (task_no_new_privs(current) && !unconfined(label) && !ctx->nnp)
1330		ctx->nnp = aa_get_label(label);
1331
1332	if (!fqname || !*fqname) {
1333		AA_DEBUG("no profile name");
1334		return -EINVAL;
1335	}
1336
1337	if (flags & AA_CHANGE_ONEXEC) {
1338		request = AA_MAY_ONEXEC;
1339		if (stack)
1340			op = OP_STACK_ONEXEC;
1341		else
1342			op = OP_CHANGE_ONEXEC;
1343	} else {
1344		request = AA_MAY_CHANGE_PROFILE;
1345		if (stack)
1346			op = OP_STACK;
1347		else
1348			op = OP_CHANGE_PROFILE;
1349	}
1350
1351	label = aa_get_current_label();
 
 
1352
1353	if (*fqname == '&') {
1354		stack = true;
1355		/* don't have label_parse() do stacking */
1356		fqname++;
 
 
 
 
 
 
1357	}
1358	target = aa_label_parse(label, fqname, GFP_KERNEL, true, false);
1359	if (IS_ERR(target)) {
1360		struct aa_profile *tprofile;
1361
1362		info = "label not found";
1363		error = PTR_ERR(target);
1364		target = NULL;
1365		/*
1366		 * TODO: fixme using labels_profile is not right - do profile
1367		 * per complain profile
1368		 */
1369		if ((flags & AA_CHANGE_TEST) ||
1370		    !COMPLAIN_MODE(labels_profile(label)))
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1371			goto audit;
1372		/* released below */
1373		tprofile = aa_new_null_profile(labels_profile(label), false,
1374					       fqname, GFP_KERNEL);
1375		if (!tprofile) {
1376			info = "failed null profile create";
1377			error = -ENOMEM;
1378			goto audit;
1379		}
1380		target = &tprofile->label;
1381		goto check;
1382	}
1383
1384	/*
1385	 * self directed transitions only apply to current policy ns
1386	 * TODO: currently requiring perms for stacking and straight change
1387	 *       stacking doesn't strictly need this. Determine how much
1388	 *       we want to loosen this restriction for stacking
1389	 *
1390	 * if (!stack) {
1391	 */
1392	error = fn_for_each_in_ns(label, profile,
1393			change_profile_perms_wrapper(op, auditname,
1394						     profile, target, stack,
1395						     request, &perms));
1396	if (error)
1397		/* auditing done in change_profile_perms_wrapper */
1398		goto out;
1399
1400	/* } */
1401
1402check:
1403	/* check if tracing task is allowed to trace target domain */
1404	error = may_change_ptraced_domain(target, &info);
1405	if (error && !fn_for_each_in_ns(label, profile,
1406					COMPLAIN_MODE(profile)))
1407		goto audit;
1408
1409	/* TODO: add permission check to allow this
1410	 * if ((flags & AA_CHANGE_ONEXEC) && !current_is_single_threaded()) {
1411	 *      info = "not a single threaded task";
1412	 *      error = -EACCES;
1413	 *      goto audit;
1414	 * }
1415	 */
1416	if (flags & AA_CHANGE_TEST)
1417		goto out;
1418
1419	/* stacking is always a subset, so only check the nonstack case */
1420	if (!stack) {
1421		new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
1422					   aa_get_label(target),
1423					   aa_get_label(&profile->label));
1424		/*
1425		 * no new privs prevents domain transitions that would
1426		 * reduce restrictions.
1427		 */
1428		if (task_no_new_privs(current) && !unconfined(label) &&
1429		    !aa_label_is_subset(new, ctx->nnp)) {
1430			/* not an apparmor denial per se, so don't log it */
1431			AA_DEBUG("no_new_privs - change_hat denied");
1432			error = -EPERM;
1433			goto out;
1434		}
1435	}
1436
1437	if (!(flags & AA_CHANGE_ONEXEC)) {
1438		/* only transition profiles in the current ns */
1439		if (stack)
1440			new = aa_label_merge(label, target, GFP_KERNEL);
1441		if (IS_ERR_OR_NULL(new)) {
1442			info = "failed to build target label";
1443			if (!new)
1444				error = -ENOMEM;
1445			else
1446				error = PTR_ERR(new);
1447			new = NULL;
1448			perms.allow = 0;
1449			goto audit;
1450		}
1451		error = aa_replace_current_label(new);
1452	} else {
1453		if (new) {
1454			aa_put_label(new);
1455			new = NULL;
1456		}
1457
1458		/* full transition will be built in exec path */
1459		error = aa_set_current_onexec(target, stack);
1460	}
 
1461
1462audit:
1463	error = fn_for_each_in_ns(label, profile,
1464			aa_audit_file(profile, &perms, op, request, auditname,
1465				      NULL, new ? new : target,
1466				      GLOBAL_ROOT_UID, info, error));
1467
1468out:
1469	aa_put_label(new);
1470	aa_put_label(target);
1471	aa_put_label(label);
1472
1473	return error;
1474}
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}