domain.c 38.1 KB
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/*
 * AppArmor security module
 *
 * This file contains AppArmor policy attachment and domain transitions
 *
 * Copyright (C) 2002-2008 Novell/SUSE
 * Copyright 2009-2010 Canonical Ltd.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, version 2 of the
 * License.
 */

#include <linux/errno.h>
#include <linux/fdtable.h>
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/syscalls.h>
#include <linux/tracehook.h>
#include <linux/personality.h>
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#include <linux/xattr.h>
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#include "include/audit.h"
#include "include/apparmorfs.h"
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#include "include/cred.h"
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#include "include/domain.h"
#include "include/file.h"
#include "include/ipc.h"
#include "include/match.h"
#include "include/path.h"
#include "include/policy.h"
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#include "include/policy_ns.h"
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/**
 * aa_free_domain_entries - free entries in a domain table
 * @domain: the domain table to free  (MAYBE NULL)
 */
void aa_free_domain_entries(struct aa_domain *domain)
{
	int i;
	if (domain) {
		if (!domain->table)
			return;

		for (i = 0; i < domain->size; i++)
			kzfree(domain->table[i]);
		kzfree(domain->table);
		domain->table = NULL;
	}
}

/**
 * may_change_ptraced_domain - check if can change profile on ptraced task
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 * @to_label: profile to change to  (NOT NULL)
 * @info: message if there is an error
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 *
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 * Check if current is ptraced and if so if the tracing task is allowed
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 * to trace the new domain
 *
 * Returns: %0 or error if change not allowed
 */
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static int may_change_ptraced_domain(struct aa_label *to_label,
				     const char **info)
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{
	struct task_struct *tracer;
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	struct aa_label *tracerl = NULL;
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	int error = 0;

	rcu_read_lock();
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	tracer = ptrace_parent(current);
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	if (tracer)
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		/* released below */
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		tracerl = aa_get_task_label(tracer);
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	/* not ptraced */
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	if (!tracer || unconfined(tracerl))
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		goto out;

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	error = aa_may_ptrace(tracerl, to_label, PTRACE_MODE_ATTACH);
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out:
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	rcu_read_unlock();
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	aa_put_label(tracerl);
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	if (error)
		*info = "ptrace prevents transition";
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	return error;
}

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/**** TODO: dedup to aa_label_match - needs perm and dfa, merging
 * specifically this is an exact copy of aa_label_match except
 * aa_compute_perms is replaced with aa_compute_fperms
 * and policy.dfa with file.dfa
 ****/
/* match a profile and its associated ns component if needed
 * Assumes visibility test has already been done.
 * If a subns profile is not to be matched should be prescreened with
 * visibility test.
 */
static inline unsigned int match_component(struct aa_profile *profile,
					   struct aa_profile *tp,
					   bool stack, unsigned int state)
{
	const char *ns_name;

	if (stack)
		state = aa_dfa_match(profile->file.dfa, state, "&");
	if (profile->ns == tp->ns)
		return aa_dfa_match(profile->file.dfa, state, tp->base.hname);

	/* try matching with namespace name and then profile */
	ns_name = aa_ns_name(profile->ns, tp->ns, true);
	state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
	state = aa_dfa_match(profile->file.dfa, state, ns_name);
	state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
	return aa_dfa_match(profile->file.dfa, state, tp->base.hname);
}

/**
 * label_compound_match - find perms for full compound label
 * @profile: profile to find perms for
 * @label: label to check access permissions for
 * @stack: whether this is a stacking request
 * @start: state to start match in
 * @subns: whether to do permission checks on components in a subns
 * @request: permissions to request
 * @perms: perms struct to set
 *
 * Returns: 0 on success else ERROR
 *
 * For the label A//&B//&C this does the perm match for A//&B//&C
 * @perms should be preinitialized with allperms OR a previous permission
 *        check to be stacked.
 */
static int label_compound_match(struct aa_profile *profile,
				struct aa_label *label, bool stack,
				unsigned int state, bool subns, u32 request,
				struct aa_perms *perms)
{
	struct aa_profile *tp;
	struct label_it i;
	struct path_cond cond = { };

	/* find first subcomponent that is visible */
	label_for_each(i, label, tp) {
		if (!aa_ns_visible(profile->ns, tp->ns, subns))
			continue;
		state = match_component(profile, tp, stack, state);
		if (!state)
			goto fail;
		goto next;
	}

	/* no component visible */
	*perms = allperms;
	return 0;

next:
	label_for_each_cont(i, label, tp) {
		if (!aa_ns_visible(profile->ns, tp->ns, subns))
			continue;
		state = aa_dfa_match(profile->file.dfa, state, "//&");
		state = match_component(profile, tp, false, state);
		if (!state)
			goto fail;
	}
	*perms = aa_compute_fperms(profile->file.dfa, state, &cond);
	aa_apply_modes_to_perms(profile, perms);
	if ((perms->allow & request) != request)
		return -EACCES;

	return 0;

fail:
	*perms = nullperms;
	return -EACCES;
}

/**
 * label_components_match - find perms for all subcomponents of a label
 * @profile: profile to find perms for
 * @label: label to check access permissions for
 * @stack: whether this is a stacking request
 * @start: state to start match in
 * @subns: whether to do permission checks on components in a subns
 * @request: permissions to request
 * @perms: an initialized perms struct to add accumulation to
 *
 * Returns: 0 on success else ERROR
 *
 * For the label A//&B//&C this does the perm match for each of A and B and C
 * @perms should be preinitialized with allperms OR a previous permission
 *        check to be stacked.
 */
static int label_components_match(struct aa_profile *profile,
				  struct aa_label *label, bool stack,
				  unsigned int start, bool subns, u32 request,
				  struct aa_perms *perms)
{
	struct aa_profile *tp;
	struct label_it i;
	struct aa_perms tmp;
	struct path_cond cond = { };
	unsigned int state = 0;

	/* find first subcomponent to test */
	label_for_each(i, label, tp) {
		if (!aa_ns_visible(profile->ns, tp->ns, subns))
			continue;
		state = match_component(profile, tp, stack, start);
		if (!state)
			goto fail;
		goto next;
	}

	/* no subcomponents visible - no change in perms */
	return 0;

next:
	tmp = aa_compute_fperms(profile->file.dfa, state, &cond);
	aa_apply_modes_to_perms(profile, &tmp);
	aa_perms_accum(perms, &tmp);
	label_for_each_cont(i, label, tp) {
		if (!aa_ns_visible(profile->ns, tp->ns, subns))
			continue;
		state = match_component(profile, tp, stack, start);
		if (!state)
			goto fail;
		tmp = aa_compute_fperms(profile->file.dfa, state, &cond);
		aa_apply_modes_to_perms(profile, &tmp);
		aa_perms_accum(perms, &tmp);
	}

	if ((perms->allow & request) != request)
		return -EACCES;

	return 0;

fail:
	*perms = nullperms;
	return -EACCES;
}

/**
 * label_match - do a multi-component label match
 * @profile: profile to match against (NOT NULL)
 * @label: label to match (NOT NULL)
 * @stack: whether this is a stacking request
 * @state: state to start in
 * @subns: whether to match subns components
 * @request: permission request
 * @perms: Returns computed perms (NOT NULL)
 *
 * Returns: the state the match finished in, may be the none matching state
 */
static int label_match(struct aa_profile *profile, struct aa_label *label,
		       bool stack, unsigned int state, bool subns, u32 request,
		       struct aa_perms *perms)
{
	int error;

	*perms = nullperms;
	error = label_compound_match(profile, label, stack, state, subns,
				     request, perms);
	if (!error)
		return error;

	*perms = allperms;
	return label_components_match(profile, label, stack, state, subns,
				      request, perms);
}

/******* end TODO: dedup *****/

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/**
 * change_profile_perms - find permissions for change_profile
 * @profile: the current profile  (NOT NULL)
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 * @target: label to transition to (NOT NULL)
 * @stack: whether this is a stacking request
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 * @request: requested perms
 * @start: state to start matching in
 *
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 *
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 * Returns: permission set
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 *
 * currently only matches full label A//&B//&C or individual components A, B, C
 * not arbitrary combinations. Eg. A//&B, C
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 */
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static int change_profile_perms(struct aa_profile *profile,
				struct aa_label *target, bool stack,
				u32 request, unsigned int start,
				struct aa_perms *perms)
{
	if (profile_unconfined(profile)) {
		perms->allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC;
		perms->audit = perms->quiet = perms->kill = 0;
		return 0;
	}

	/* TODO: add profile in ns screening */
	return label_match(profile, target, stack, start, true, request, perms);
}

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/**
 * aa_xattrs_match - check whether a file matches the xattrs defined in profile
 * @bprm: binprm struct for the process to validate
 * @profile: profile to match against (NOT NULL)
 *
 * Returns: number of extended attributes that matched, or < 0 on error
 */
static int aa_xattrs_match(const struct linux_binprm *bprm,
			   struct aa_profile *profile)
{
	int i;
	size_t size;
	struct dentry *d;
	char *value = NULL;
	int value_size = 0, ret = profile->xattr_count;

	if (!bprm || !profile->xattr_count)
		return 0;

	d = bprm->file->f_path.dentry;

	for (i = 0; i < profile->xattr_count; i++) {
		size = vfs_getxattr_alloc(d, profile->xattrs[i], &value,
					  value_size, GFP_KERNEL);
		if (size < 0) {
			ret = -EINVAL;
			goto out;
		}

		/* Check the xattr value, not just presence */
		if (profile->xattr_lens[i]) {
			if (profile->xattr_lens[i] != size) {
				ret = -EINVAL;
				goto out;
			}

			if (memcmp(value, profile->xattr_values[i], size)) {
				ret = -EINVAL;
				goto out;
			}
		}
	}

out:
	kfree(value);
	return ret;
}

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/**
 * __attach_match_ - find an attachment match
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 * @bprm - binprm structure of transitioning task
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 * @name - to match against  (NOT NULL)
 * @head - profile list to walk  (NOT NULL)
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 * @info - info message if there was an error (NOT NULL)
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 *
 * Do a linear search on the profiles in the list.  There is a matching
 * preference where an exact match is preferred over a name which uses
 * expressions to match, and matching expressions with the greatest
 * xmatch_len are preferred.
 *
 * Requires: @head not be shared or have appropriate locks held
 *
 * Returns: profile or NULL if no match found
 */
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static struct aa_profile *__attach_match(const struct linux_binprm *bprm,
					 const char *name,
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					 struct list_head *head,
					 const char **info)
373
{
374
	int len = 0, xattrs = 0;
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	bool conflict = false;
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	struct aa_profile *profile, *candidate = NULL;

378
	list_for_each_entry_rcu(profile, head, base.list) {
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		if (profile->label.flags & FLAG_NULL &&
		    &profile->label == ns_unconfined(profile->ns))
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			continue;
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		/* Find the "best" matching profile. Profiles must
		 * match the path and extended attributes (if any)
		 * associated with the file. A more specific path
		 * match will be preferred over a less specific one,
		 * and a match with more matching extended attributes
		 * will be preferred over one with fewer. If the best
		 * match has both the same level of path specificity
		 * and the same number of matching extended attributes
		 * as another profile, signal a conflict and refuse to
		 * match.
		 */
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		if (profile->xmatch) {
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			unsigned int state;
			u32 perm;

			if (profile->xmatch_len < len)
				continue;

			state = aa_dfa_match(profile->xmatch,
					     DFA_START, name);
			perm = dfa_user_allow(profile->xmatch, state);
			/* any accepting state means a valid match. */
			if (perm & MAY_EXEC) {
				int ret = aa_xattrs_match(bprm, profile);

				/* Fail matching if the xattrs don't match */
				if (ret < 0)
					continue;

				/* The new match isn't more specific
				 * than the current best match
				 */
				if (profile->xmatch_len == len &&
				    ret <= xattrs) {
					/* Match is equivalent, so conflict */
					if (ret == xattrs)
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						conflict = true;
420
					continue;
421
				}
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				/* Either the same length with more matching
				 * xattrs, or a longer match
				 */
				candidate = profile;
				len = profile->xmatch_len;
				xattrs = ret;
				conflict = false;
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			}
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		} else if (!strcmp(profile->base.name, name) &&
			   aa_xattrs_match(bprm, profile) >= 0)
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			/* exact non-re match, no more searching required */
			return profile;
	}

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	if (conflict) {
		*info = "conflicting profile attachments";
		return NULL;
	}

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	return candidate;
}

/**
 * find_attach - do attachment search for unconfined processes
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 * @bprm - binprm structure of transitioning task
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 * @ns: the current namespace  (NOT NULL)
 * @list: list to search  (NOT NULL)
 * @name: the executable name to match against  (NOT NULL)
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 * @info: info message if there was an error
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 *
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 * Returns: label or NULL if no match found
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 */
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static struct aa_label *find_attach(const struct linux_binprm *bprm,
				    struct aa_ns *ns, struct list_head *list,
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				    const char *name, const char **info)
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{
	struct aa_profile *profile;

461
	rcu_read_lock();
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	profile = aa_get_profile(__attach_match(bprm, name, list, info));
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	rcu_read_unlock();
464

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	return profile ? &profile->label : NULL;
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}

static const char *next_name(int xtype, const char *name)
{
	return NULL;
}

/**
 * x_table_lookup - lookup an x transition name via transition table
 * @profile: current profile (NOT NULL)
 * @xindex: index into x transition table
477
 * @name: returns: name tested to find label (NOT NULL)
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 *
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 * Returns: refcounted label, or NULL on failure (MAYBE NULL)
480
 */
J
John Johansen 已提交
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struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
				const char **name)
483
{
484
	struct aa_label *label = NULL;
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	u32 xtype = xindex & AA_X_TYPE_MASK;
	int index = xindex & AA_X_INDEX_MASK;

488
	AA_BUG(!name);
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	/* index is guaranteed to be in range, validated at load time */
	/* TODO: move lookup parsing to unpack time so this is a straight
	 *       index into the resultant label
	 */
	for (*name = profile->file.trans.table[index]; !label && *name;
	     *name = next_name(xtype, *name)) {
496
		if (xindex & AA_X_CHILD) {
497
			struct aa_profile *new_profile;
498
			/* release by caller */
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			new_profile = aa_find_child(profile, *name);
			if (new_profile)
				label = &new_profile->label;
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			continue;
		}
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		label = aa_label_parse(&profile->label, *name, GFP_ATOMIC,
				       true, false);
		if (IS_ERR(label))
			label = NULL;
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	}

	/* released by caller */
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	return label;
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}

/**
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 * x_to_label - get target label for a given xindex
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 * @profile: current profile  (NOT NULL)
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 * @bprm: binprm structure of transitioning task
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 * @name: name to lookup (NOT NULL)
 * @xindex: index into x transition table
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 * @lookupname: returns: name used in lookup if one was specified (NOT NULL)
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 *
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 * find label for a transition index
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 *
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 * Returns: refcounted label or NULL if not found available
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 */
527
static struct aa_label *x_to_label(struct aa_profile *profile,
528
				   const struct linux_binprm *bprm,
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				   const char *name, u32 xindex,
				   const char **lookupname,
				   const char **info)
532
{
533
	struct aa_label *new = NULL;
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	struct aa_ns *ns = profile->ns;
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	u32 xtype = xindex & AA_X_TYPE_MASK;
536
	const char *stack = NULL;
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	switch (xtype) {
	case AA_X_NONE:
		/* fail exec unless ix || ux fallback - handled by caller */
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		*lookupname = NULL;
		break;
	case AA_X_TABLE:
		/* TODO: fix when perm mapping done at unload */
		stack = profile->file.trans.table[xindex & AA_X_INDEX_MASK];
		if (*stack != '&') {
			/* released by caller */
			new = x_table_lookup(profile, xindex, lookupname);
			stack = NULL;
			break;
		}
		/* fall through to X_NAME */
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	case AA_X_NAME:
		if (xindex & AA_X_CHILD)
			/* released by caller */
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			new = find_attach(bprm, ns, &profile->base.profiles,
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					  name, info);
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		else
			/* released by caller */
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			new = find_attach(bprm, ns, &ns->base.profiles,
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					  name, info);
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		*lookupname = name;
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		break;
	}

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	if (!new) {
		if (xindex & AA_X_INHERIT) {
			/* (p|c|n)ix - don't change profile but do
			 * use the newest version
			 */
			*info = "ix fallback";
			/* no profile && no error */
			new = aa_get_newest_label(&profile->label);
		} else if (xindex & AA_X_UNCONFINED) {
			new = aa_get_newest_label(ns_unconfined(profile->ns));
			*info = "ux fallback";
		}
	}

	if (new && stack) {
		/* base the stack on post domain transition */
		struct aa_label *base = new;

		new = aa_label_parse(base, stack, GFP_ATOMIC, true, false);
		if (IS_ERR(new))
			new = NULL;
		aa_put_label(base);
	}

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	/* released by caller */
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	return new;
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}

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static struct aa_label *profile_transition(struct aa_profile *profile,
					   const struct linux_binprm *bprm,
					   char *buffer, struct path_cond *cond,
					   bool *secure_exec)
598
{
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	struct aa_label *new = NULL;
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	struct aa_profile *component;
	struct label_it i;
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	const char *info = NULL, *name = NULL, *target = NULL;
	unsigned int state = profile->file.start;
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	struct aa_perms perms = {};
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	bool nonewprivs = false;
C
Casey Schaufler 已提交
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	int error = 0;
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	AA_BUG(!profile);
	AA_BUG(!bprm);
	AA_BUG(!buffer);
611

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	error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
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			     &name, &info, profile->disconnected);
614
	if (error) {
615
		if (profile_unconfined(profile) ||
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		    (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
			AA_DEBUG("name lookup ix on error");
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			error = 0;
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			new = aa_get_newest_label(&profile->label);
		}
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		name = bprm->filename;
		goto audit;
	}

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	if (profile_unconfined(profile)) {
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		new = find_attach(bprm, profile->ns,
				  &profile->ns->base.profiles, name, &info);
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		if (new) {
			AA_DEBUG("unconfined attached to new label");
			return new;
		}
		AA_DEBUG("unconfined exec no attachment");
		return aa_get_newest_label(&profile->label);
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	}

	/* find exec permissions for name */
637
	state = aa_str_perms(profile->file.dfa, state, name, cond, &perms);
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	if (perms.allow & MAY_EXEC) {
		/* exec permission determine how to transition */
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		new = x_to_label(profile, bprm, name, perms.xindex, &target,
				 &info);
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		if (new && new->proxy == profile->label.proxy && info) {
			/* hack ix fallback - improve how this is detected */
			goto audit;
		} else if (!new) {
			error = -EACCES;
			info = "profile transition not found";
			/* remove MAY_EXEC to audit as failure */
			perms.allow &= ~MAY_EXEC;
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		} else {
			/* verify that each component's xattr requirements are
			 * met, and fail execution otherwise
			 */
			label_for_each(i, new, component) {
				if (aa_xattrs_match(bprm, component) < 0) {
					error = -EACCES;
					info = "required xattrs not present";
					perms.allow &= ~MAY_EXEC;
					aa_put_label(new);
					new = NULL;
					goto audit;
				}
			}
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		}
	} else if (COMPLAIN_MODE(profile)) {
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		/* no exec permission - learning mode */
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		struct aa_profile *new_profile = NULL;
		char *n = kstrdup(name, GFP_ATOMIC);

		if (n) {
			/* name is ptr into buffer */
			long pos = name - buffer;
			/* break per cpu buffer hold */
			put_buffers(buffer);
			new_profile = aa_new_null_profile(profile, false, n,
							  GFP_KERNEL);
			get_buffers(buffer);
			name = buffer + pos;
			strcpy((char *)name, n);
			kfree(n);
		}
682 683 684
		if (!new_profile) {
			error = -ENOMEM;
			info = "could not create null profile";
685
		} else {
686
			error = -EACCES;
687 688
			new = &new_profile->label;
		}
689 690 691 692 693
		perms.xindex |= AA_X_UNSAFE;
	} else
		/* fail exec */
		error = -EACCES;

694 695 696 697 698 699 700 701 702 703 704 705
	if (!new)
		goto audit;


	if (!(perms.xindex & AA_X_UNSAFE)) {
		if (DEBUG_ON) {
			dbg_printk("apparmor: scrubbing environment variables"
				   " for %s profile=", name);
			aa_label_printk(new, GFP_ATOMIC);
			dbg_printk("\n");
		}
		*secure_exec = true;
706 707
	}

708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752
audit:
	aa_audit_file(profile, &perms, OP_EXEC, MAY_EXEC, name, target, new,
		      cond->uid, info, error);
	if (!new || nonewprivs) {
		aa_put_label(new);
		return ERR_PTR(error);
	}

	return new;
}

static int profile_onexec(struct aa_profile *profile, struct aa_label *onexec,
			  bool stack, const struct linux_binprm *bprm,
			  char *buffer, struct path_cond *cond,
			  bool *secure_exec)
{
	unsigned int state = profile->file.start;
	struct aa_perms perms = {};
	const char *xname = NULL, *info = "change_profile onexec";
	int error = -EACCES;

	AA_BUG(!profile);
	AA_BUG(!onexec);
	AA_BUG(!bprm);
	AA_BUG(!buffer);

	if (profile_unconfined(profile)) {
		/* change_profile on exec already granted */
		/*
		 * NOTE: Domain transitions from unconfined are allowed
		 * even when no_new_privs is set because this aways results
		 * in a further reduction of permissions.
		 */
		return 0;
	}

	error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
			     &xname, &info, profile->disconnected);
	if (error) {
		if (profile_unconfined(profile) ||
		    (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
			AA_DEBUG("name lookup ix on error");
			error = 0;
		}
		xname = bprm->filename;
753
		goto audit;
754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852
	}

	/* find exec permissions for name */
	state = aa_str_perms(profile->file.dfa, state, xname, cond, &perms);
	if (!(perms.allow & AA_MAY_ONEXEC)) {
		info = "no change_onexec valid for executable";
		goto audit;
	}
	/* test if this exec can be paired with change_profile onexec.
	 * onexec permission is linked to exec with a standard pairing
	 * exec\0change_profile
	 */
	state = aa_dfa_null_transition(profile->file.dfa, state);
	error = change_profile_perms(profile, onexec, stack, AA_MAY_ONEXEC,
				     state, &perms);
	if (error) {
		perms.allow &= ~AA_MAY_ONEXEC;
		goto audit;
	}

	if (!(perms.xindex & AA_X_UNSAFE)) {
		if (DEBUG_ON) {
			dbg_printk("apparmor: scrubbing environment "
				   "variables for %s label=", xname);
			aa_label_printk(onexec, GFP_ATOMIC);
			dbg_printk("\n");
		}
		*secure_exec = true;
	}

audit:
	return aa_audit_file(profile, &perms, OP_EXEC, AA_MAY_ONEXEC, xname,
			     NULL, onexec, cond->uid, info, error);
}

/* ensure none ns domain transitions are correctly applied with onexec */

static struct aa_label *handle_onexec(struct aa_label *label,
				      struct aa_label *onexec, bool stack,
				      const struct linux_binprm *bprm,
				      char *buffer, struct path_cond *cond,
				      bool *unsafe)
{
	struct aa_profile *profile;
	struct aa_label *new;
	int error;

	AA_BUG(!label);
	AA_BUG(!onexec);
	AA_BUG(!bprm);
	AA_BUG(!buffer);

	if (!stack) {
		error = fn_for_each_in_ns(label, profile,
				profile_onexec(profile, onexec, stack,
					       bprm, buffer, cond, unsafe));
		if (error)
			return ERR_PTR(error);
		new = fn_label_build_in_ns(label, profile, GFP_ATOMIC,
				aa_get_newest_label(onexec),
				profile_transition(profile, bprm, buffer,
						   cond, unsafe));

	} else {
		/* TODO: determine how much we want to losen this */
		error = fn_for_each_in_ns(label, profile,
				profile_onexec(profile, onexec, stack, bprm,
					       buffer, cond, unsafe));
		if (error)
			return ERR_PTR(error);
		new = fn_label_build_in_ns(label, profile, GFP_ATOMIC,
				aa_label_merge(&profile->label, onexec,
					       GFP_ATOMIC),
				profile_transition(profile, bprm, buffer,
						   cond, unsafe));
	}

	if (new)
		return new;

	/* TODO: get rid of GLOBAL_ROOT_UID */
	error = fn_for_each_in_ns(label, profile,
			aa_audit_file(profile, &nullperms, OP_CHANGE_ONEXEC,
				      AA_MAY_ONEXEC, bprm->filename, NULL,
				      onexec, GLOBAL_ROOT_UID,
				      "failed to build target label", -ENOMEM));
	return ERR_PTR(error);
}

/**
 * apparmor_bprm_set_creds - set the new creds on the bprm struct
 * @bprm: binprm for the exec  (NOT NULL)
 *
 * Returns: %0 or error on failure
 *
 * TODO: once the other paths are done see if we can't refactor into a fn
 */
int apparmor_bprm_set_creds(struct linux_binprm *bprm)
{
J
John Johansen 已提交
853
	struct aa_task_ctx *ctx;
854 855 856 857 858 859 860 861 862 863 864
	struct aa_label *label, *new = NULL;
	struct aa_profile *profile;
	char *buffer = NULL;
	const char *info = NULL;
	int error = 0;
	bool unsafe = false;
	struct path_cond cond = {
		file_inode(bprm->file)->i_uid,
		file_inode(bprm->file)->i_mode
	};

865
	if (bprm->called_set_creds)
866 867
		return 0;

868
	ctx = task_ctx(current);
869
	AA_BUG(!cred_label(bprm->cred));
J
John Johansen 已提交
870
	AA_BUG(!ctx);
871

872
	label = aa_get_newest_label(cred_label(bprm->cred));
873

874 875 876 877 878 879 880 881 882 883 884
	/*
	 * Detect no new privs being set, and store the label it
	 * occurred under. Ideally this would happen when nnp
	 * is set but there isn't a good way to do that yet.
	 *
	 * Testing for unconfined must be done before the subset test
	 */
	if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) && !unconfined(label) &&
	    !ctx->nnp)
		ctx->nnp = aa_get_label(label);

885 886 887
	/* buffer freed below, name is pointer into buffer */
	get_buffers(buffer);
	/* Test for onexec first as onexec override other x transitions. */
J
John Johansen 已提交
888 889
	if (ctx->onexec)
		new = handle_onexec(label, ctx->onexec, ctx->token,
890 891 892 893 894 895 896 897 898 899 900 901 902 903 904
				    bprm, buffer, &cond, &unsafe);
	else
		new = fn_label_build(label, profile, GFP_ATOMIC,
				profile_transition(profile, bprm, buffer,
						   &cond, &unsafe));

	AA_BUG(!new);
	if (IS_ERR(new)) {
		error = PTR_ERR(new);
		goto done;
	} else if (!new) {
		error = -ENOMEM;
		goto done;
	}

905 906 907 908 909 910 911 912 913 914 915 916 917 918
	/* Policy has specified a domain transitions. If no_new_privs and
	 * confined ensure the transition is to confinement that is subset
	 * of the confinement when the task entered no new privs.
	 *
	 * NOTE: Domain transitions from unconfined and to stacked
	 * subsets are allowed even when no_new_privs is set because this
	 * aways results in a further reduction of permissions.
	 */
	if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) &&
	    !unconfined(label) && !aa_label_is_subset(new, ctx->nnp)) {
		error = -EPERM;
		info = "no new privs";
		goto audit;
	}
919 920 921 922 923 924

	if (bprm->unsafe & LSM_UNSAFE_SHARE) {
		/* FIXME: currently don't mediate shared state */
		;
	}

925 926 927
	if (bprm->unsafe & (LSM_UNSAFE_PTRACE)) {
		/* TODO: test needs to be profile of label to new */
		error = may_change_ptraced_domain(new, &info);
928
		if (error)
929 930 931
			goto audit;
	}

932 933 934 935 936 937 938
	if (unsafe) {
		if (DEBUG_ON) {
			dbg_printk("scrubbing environment variables for %s "
				   "label=", bprm->filename);
			aa_label_printk(new, GFP_ATOMIC);
			dbg_printk("\n");
		}
939
		bprm->secureexec = 1;
940 941
	}

942 943 944 945 946 947 948 949 950 951
	if (label->proxy != new->proxy) {
		/* when transitioning clear unsafe personality bits */
		if (DEBUG_ON) {
			dbg_printk("apparmor: clearing unsafe personality "
				   "bits. %s label=", bprm->filename);
			aa_label_printk(new, GFP_ATOMIC);
			dbg_printk("\n");
		}
		bprm->per_clear |= PER_CLEAR_ON_SETID;
	}
952 953 954
	aa_put_label(cred_label(bprm->cred));
	/* transfer reference, released when cred is freed */
	cred_label(bprm->cred) = new;
955

956
done:
957
	aa_put_label(label);
958
	put_buffers(buffer);
959 960

	return error;
961 962 963 964 965 966 967 968 969

audit:
	error = fn_for_each(label, profile,
			aa_audit_file(profile, &nullperms, OP_EXEC, MAY_EXEC,
				      bprm->filename, NULL, new,
				      file_inode(bprm->file)->i_uid, info,
				      error));
	aa_put_label(new);
	goto done;
970 971 972 973 974 975
}

/*
 * Functions for self directed profile change
 */

976 977

/* helper fn for change_hat
978
 *
979
 * Returns: label for hat transition OR ERR_PTR.  Does NOT return NULL
980
 */
981 982
static struct aa_label *build_change_hat(struct aa_profile *profile,
					 const char *name, bool sibling)
983
{
984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122
	struct aa_profile *root, *hat = NULL;
	const char *info = NULL;
	int error = 0;

	if (sibling && PROFILE_IS_HAT(profile)) {
		root = aa_get_profile_rcu(&profile->parent);
	} else if (!sibling && !PROFILE_IS_HAT(profile)) {
		root = aa_get_profile(profile);
	} else {
		info = "conflicting target types";
		error = -EPERM;
		goto audit;
	}

	hat = aa_find_child(root, name);
	if (!hat) {
		error = -ENOENT;
		if (COMPLAIN_MODE(profile)) {
			hat = aa_new_null_profile(profile, true, name,
						  GFP_KERNEL);
			if (!hat) {
				info = "failed null profile create";
				error = -ENOMEM;
			}
		}
	}
	aa_put_profile(root);

audit:
	aa_audit_file(profile, &nullperms, OP_CHANGE_HAT, AA_MAY_CHANGEHAT,
		      name, hat ? hat->base.hname : NULL,
		      hat ? &hat->label : NULL, GLOBAL_ROOT_UID, NULL,
		      error);
	if (!hat || (error && error != -ENOENT))
		return ERR_PTR(error);
	/* if hat && error - complain mode, already audited and we adjust for
	 * complain mode allow by returning hat->label
	 */
	return &hat->label;
}

/* helper fn for changing into a hat
 *
 * Returns: label for hat transition or ERR_PTR. Does not return NULL
 */
static struct aa_label *change_hat(struct aa_label *label, const char *hats[],
				   int count, int flags)
{
	struct aa_profile *profile, *root, *hat = NULL;
	struct aa_label *new;
	struct label_it it;
	bool sibling = false;
	const char *name, *info = NULL;
	int i, error;

	AA_BUG(!label);
	AA_BUG(!hats);
	AA_BUG(count < 1);

	if (PROFILE_IS_HAT(labels_profile(label)))
		sibling = true;

	/*find first matching hat */
	for (i = 0; i < count && !hat; i++) {
		name = hats[i];
		label_for_each_in_ns(it, labels_ns(label), label, profile) {
			if (sibling && PROFILE_IS_HAT(profile)) {
				root = aa_get_profile_rcu(&profile->parent);
			} else if (!sibling && !PROFILE_IS_HAT(profile)) {
				root = aa_get_profile(profile);
			} else {	/* conflicting change type */
				info = "conflicting targets types";
				error = -EPERM;
				goto fail;
			}
			hat = aa_find_child(root, name);
			aa_put_profile(root);
			if (!hat) {
				if (!COMPLAIN_MODE(profile))
					goto outer_continue;
				/* complain mode succeed as if hat */
			} else if (!PROFILE_IS_HAT(hat)) {
				info = "target not hat";
				error = -EPERM;
				aa_put_profile(hat);
				goto fail;
			}
			aa_put_profile(hat);
		}
		/* found a hat for all profiles in ns */
		goto build;
outer_continue:
	;
	}
	/* no hats that match, find appropriate error
	 *
	 * In complain mode audit of the failure is based off of the first
	 * hat supplied.  This is done due how userspace interacts with
	 * change_hat.
	 */
	name = NULL;
	label_for_each_in_ns(it, labels_ns(label), label, profile) {
		if (!list_empty(&profile->base.profiles)) {
			info = "hat not found";
			error = -ENOENT;
			goto fail;
		}
	}
	info = "no hats defined";
	error = -ECHILD;

fail:
	label_for_each_in_ns(it, labels_ns(label), label, profile) {
		/*
		 * no target as it has failed to be found or built
		 *
		 * change_hat uses probing and should not log failures
		 * related to missing hats
		 */
		/* TODO: get rid of GLOBAL_ROOT_UID */
		if (count > 1 || COMPLAIN_MODE(profile)) {
			aa_audit_file(profile, &nullperms, OP_CHANGE_HAT,
				      AA_MAY_CHANGEHAT, name, NULL, NULL,
				      GLOBAL_ROOT_UID, info, error);
		}
	}
	return ERR_PTR(error);

build:
	new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
				   build_change_hat(profile, name, sibling),
				   aa_get_label(&profile->label));
	if (!new) {
		info = "label build failed";
		error = -ENOMEM;
		goto fail;
	} /* else if (IS_ERR) build_change_hat has logged error so return new */

	return new;
1123 1124 1125 1126 1127 1128 1129
}

/**
 * aa_change_hat - change hat to/from subprofile
 * @hats: vector of hat names to try changing into (MAYBE NULL if @count == 0)
 * @count: number of hat names in @hats
 * @token: magic value to validate the hat change
1130
 * @flags: flags affecting behavior of the change
1131
 *
1132 1133
 * Returns %0 on success, error otherwise.
 *
1134 1135 1136 1137 1138
 * Change to the first profile specified in @hats that exists, and store
 * the @hat_magic in the current task context.  If the count == 0 and the
 * @token matches that stored in the current task context, return to the
 * top level profile.
 *
1139 1140
 * change_hat only applies to profiles in the current ns, and each profile
 * in the ns must make the same transition otherwise change_hat will fail.
1141
 */
1142
int aa_change_hat(const char *hats[], int count, u64 token, int flags)
1143 1144
{
	const struct cred *cred;
1145
	struct aa_task_ctx *ctx = task_ctx(current);
1146 1147
	struct aa_label *label, *previous, *new = NULL, *target = NULL;
	struct aa_profile *profile;
1148
	struct aa_perms perms = {};
1149
	const char *info = NULL;
1150 1151 1152 1153
	int error = 0;

	/* released below */
	cred = get_current_cred();
1154
	label = aa_get_newest_cred_label(cred);
J
John Johansen 已提交
1155
	previous = aa_get_newest_label(ctx->previous);
1156

1157 1158 1159 1160 1161 1162 1163 1164 1165 1166
	/*
	 * Detect no new privs being set, and store the label it
	 * occurred under. Ideally this would happen when nnp
	 * is set but there isn't a good way to do that yet.
	 *
	 * Testing for unconfined must be done before the subset test
	 */
	if (task_no_new_privs(current) && !unconfined(label) && !ctx->nnp)
		ctx->nnp = aa_get_label(label);

1167
	if (unconfined(label)) {
1168
		info = "unconfined can not change_hat";
1169
		error = -EPERM;
1170
		goto fail;
1171 1172 1173
	}

	if (count) {
1174 1175 1176 1177 1178 1179 1180
		new = change_hat(label, hats, count, flags);
		AA_BUG(!new);
		if (IS_ERR(new)) {
			error = PTR_ERR(new);
			new = NULL;
			/* already audited */
			goto out;
1181 1182
		}

1183 1184 1185
		error = may_change_ptraced_domain(new, &info);
		if (error)
			goto fail;
1186

1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198
		/*
		 * no new privs prevents domain transitions that would
		 * reduce restrictions.
		 */
		if (task_no_new_privs(current) && !unconfined(label) &&
		    !aa_label_is_subset(new, ctx->nnp)) {
			/* not an apparmor denial per se, so don't log it */
			AA_DEBUG("no_new_privs - change_hat denied");
			error = -EPERM;
			goto out;
		}

1199 1200 1201 1202 1203 1204 1205 1206 1207
		if (flags & AA_CHANGE_TEST)
			goto out;

		target = new;
		error = aa_set_current_hat(new, token);
		if (error == -EACCES)
			/* kill task in case of brute force attacks */
			goto kill;
	} else if (previous && !(flags & AA_CHANGE_TEST)) {
1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219
		/*
		 * no new privs prevents domain transitions that would
		 * reduce restrictions.
		 */
		if (task_no_new_privs(current) && !unconfined(label) &&
		    !aa_label_is_subset(previous, ctx->nnp)) {
			/* not an apparmor denial per se, so don't log it */
			AA_DEBUG("no_new_privs - change_hat denied");
			error = -EPERM;
			goto out;
		}

1220
		/* Return to saved label.  Kill task if restore fails
1221 1222
		 * to avoid brute force attacks
		 */
1223
		target = previous;
1224
		error = aa_restore_previous_label(token);
1225 1226 1227 1228 1229 1230
		if (error) {
			if (error == -EACCES)
				goto kill;
			goto fail;
		}
	} /* else ignore @flags && restores when there is no saved profile */
1231 1232

out:
1233 1234
	aa_put_label(new);
	aa_put_label(previous);
1235
	aa_put_label(label);
1236 1237 1238
	put_cred(cred);

	return error;
1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250

kill:
	info = "failed token match";
	perms.kill = AA_MAY_CHANGEHAT;

fail:
	fn_for_each_in_ns(label, profile,
		aa_audit_file(profile, &perms, OP_CHANGE_HAT,
			      AA_MAY_CHANGEHAT, NULL, NULL, target,
			      GLOBAL_ROOT_UID, info, error));

	goto out;
1251 1252
}

1253

1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271
static int change_profile_perms_wrapper(const char *op, const char *name,
					struct aa_profile *profile,
					struct aa_label *target, bool stack,
					u32 request, struct aa_perms *perms)
{
	const char *info = NULL;
	int error = 0;

	if (!error)
		error = change_profile_perms(profile, target, stack, request,
					     profile->file.start, perms);
	if (error)
		error = aa_audit_file(profile, perms, op, request, name,
				      NULL, target, GLOBAL_ROOT_UID, info,
				      error);

	return error;
}
1272

1273 1274
/**
 * aa_change_profile - perform a one-way profile transition
1275
 * @fqname: name of profile may include namespace (NOT NULL)
1276
 * @onexec: whether this transition is to take place immediately or at exec
1277
 * @flags: flags affecting change behavior
1278 1279 1280 1281 1282 1283 1284 1285 1286
 *
 * Change to new profile @name.  Unlike with hats, there is no way
 * to change back.  If @name isn't specified the current profile name is
 * used.
 * If @onexec then the transition is delayed until
 * the next exec.
 *
 * Returns %0 on success, error otherwise.
 */
1287
int aa_change_profile(const char *fqname, int flags)
1288
{
1289 1290
	struct aa_label *label, *new = NULL, *target = NULL;
	struct aa_profile *profile;
1291
	struct aa_perms perms = {};
1292 1293 1294
	const char *info = NULL;
	const char *auditname = fqname;		/* retain leading & if stack */
	bool stack = flags & AA_CHANGE_STACK;
1295
	struct aa_task_ctx *ctx = task_ctx(current);
1296
	int error = 0;
1297
	char *op;
1298 1299
	u32 request;

1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311
	label = aa_get_current_label();

	/*
	 * Detect no new privs being set, and store the label it
	 * occurred under. Ideally this would happen when nnp
	 * is set but there isn't a good way to do that yet.
	 *
	 * Testing for unconfined must be done before the subset test
	 */
	if (task_no_new_privs(current) && !unconfined(label) && !ctx->nnp)
		ctx->nnp = aa_get_label(label);

1312 1313
	if (!fqname || !*fqname) {
		AA_DEBUG("no profile name");
1314
		return -EINVAL;
1315
	}
1316

1317
	if (flags & AA_CHANGE_ONEXEC) {
1318
		request = AA_MAY_ONEXEC;
1319 1320 1321 1322
		if (stack)
			op = OP_STACK_ONEXEC;
		else
			op = OP_CHANGE_ONEXEC;
1323 1324
	} else {
		request = AA_MAY_CHANGE_PROFILE;
1325 1326 1327 1328
		if (stack)
			op = OP_STACK;
		else
			op = OP_CHANGE_PROFILE;
1329 1330
	}

1331
	label = aa_get_current_label();
1332

1333 1334 1335 1336
	if (*fqname == '&') {
		stack = true;
		/* don't have label_parse() do stacking */
		fqname++;
1337
	}
1338 1339 1340
	target = aa_label_parse(label, fqname, GFP_KERNEL, true, false);
	if (IS_ERR(target)) {
		struct aa_profile *tprofile;
1341

1342 1343 1344 1345 1346 1347 1348
		info = "label not found";
		error = PTR_ERR(target);
		target = NULL;
		/*
		 * TODO: fixme using labels_profile is not right - do profile
		 * per complain profile
		 */
1349
		if ((flags & AA_CHANGE_TEST) ||
1350
		    !COMPLAIN_MODE(labels_profile(label)))
1351 1352
			goto audit;
		/* released below */
1353 1354 1355
		tprofile = aa_new_null_profile(labels_profile(label), false,
					       fqname, GFP_KERNEL);
		if (!tprofile) {
1356 1357 1358 1359
			info = "failed null profile create";
			error = -ENOMEM;
			goto audit;
		}
1360 1361
		target = &tprofile->label;
		goto check;
1362 1363
	}

1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378
	/*
	 * self directed transitions only apply to current policy ns
	 * TODO: currently requiring perms for stacking and straight change
	 *       stacking doesn't strictly need this. Determine how much
	 *       we want to loosen this restriction for stacking
	 *
	 * if (!stack) {
	 */
	error = fn_for_each_in_ns(label, profile,
			change_profile_perms_wrapper(op, auditname,
						     profile, target, stack,
						     request, &perms));
	if (error)
		/* auditing done in change_profile_perms_wrapper */
		goto out;
1379

1380 1381 1382
	/* } */

check:
1383
	/* check if tracing task is allowed to trace target domain */
1384 1385 1386
	error = may_change_ptraced_domain(target, &info);
	if (error && !fn_for_each_in_ns(label, profile,
					COMPLAIN_MODE(profile)))
1387 1388
		goto audit;

1389 1390 1391 1392 1393 1394 1395
	/* TODO: add permission check to allow this
	 * if ((flags & AA_CHANGE_ONEXEC) && !current_is_single_threaded()) {
	 *      info = "not a single threaded task";
	 *      error = -EACCES;
	 *      goto audit;
	 * }
	 */
1396
	if (flags & AA_CHANGE_TEST)
1397
		goto out;
1398

1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416
	/* stacking is always a subset, so only check the nonstack case */
	if (!stack) {
		new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
					   aa_get_label(target),
					   aa_get_label(&profile->label));
		/*
		 * no new privs prevents domain transitions that would
		 * reduce restrictions.
		 */
		if (task_no_new_privs(current) && !unconfined(label) &&
		    !aa_label_is_subset(new, ctx->nnp)) {
			/* not an apparmor denial per se, so don't log it */
			AA_DEBUG("no_new_privs - change_hat denied");
			error = -EPERM;
			goto out;
		}
	}

1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428
	if (!(flags & AA_CHANGE_ONEXEC)) {
		/* only transition profiles in the current ns */
		if (stack)
			new = aa_label_merge(label, target, GFP_KERNEL);
		if (IS_ERR_OR_NULL(new)) {
			info = "failed to build target label";
			error = PTR_ERR(new);
			new = NULL;
			perms.allow = 0;
			goto audit;
		}
		error = aa_replace_current_label(new);
1429 1430 1431 1432 1433 1434
	} else {
		if (new) {
			aa_put_label(new);
			new = NULL;
		}

1435 1436
		/* full transition will be built in exec path */
		error = aa_set_current_onexec(target, stack);
1437
	}
1438 1439

audit:
1440 1441 1442 1443
	error = fn_for_each_in_ns(label, profile,
			aa_audit_file(profile, &perms, op, request, auditname,
				      NULL, new ? new : target,
				      GLOBAL_ROOT_UID, info, error));
1444

1445 1446 1447
out:
	aa_put_label(new);
	aa_put_label(target);
1448
	aa_put_label(label);
1449 1450 1451

	return error;
}