AppArmor: functions for domain transitions

AppArmor routines for controling domain transitions, which can occur at
exec or through self directed change_profile/change_hat calls.

Unconfined tasks are checked at exec against the profiles in the confining
profile namespace to determine if a profile should be attached to the task.

Confined tasks execs are controlled by the profile which provides rules
determining which execs are allowed and if so which profiles should be
transitioned to.

Self directed domain transitions allow a task to request transition
to a given profile.  If the transition is allowed then the profile will
be applied, either immeditately or at exec time depending on the request.
Immeditate self directed transitions have several security limitations
but have uses in setting up stub transition profiles and other limited
cases.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <jmorris@namei.org>

security/apparmor/domain.c

+/*
+ * 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>
+
+#include "include/audit.h"
+#include "include/apparmorfs.h"
+#include "include/context.h"
+#include "include/domain.h"
+#include "include/file.h"
+#include "include/ipc.h"
+#include "include/match.h"
+#include "include/path.h"
+#include "include/policy.h"
+
+/**
+ * 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
+ * @task: task we want to change profile of   (NOT NULL)
+ * @to_profile: profile to change to  (NOT NULL)
+ *
+ * Check if the task is ptraced and if so if the tracing task is allowed
+ * to trace the new domain
+ *
+ * Returns: %0 or error if change not allowed
+ */
+static int may_change_ptraced_domain(struct task_struct *task,
+				     struct aa_profile *to_profile)
+{
+	struct task_struct *tracer;
+	struct cred *cred = NULL;
+	struct aa_profile *tracerp = NULL;
+	int error = 0;
+
+	rcu_read_lock();
+	tracer = tracehook_tracer_task(task);
+	if (tracer) {
+		/* released below */
+		cred = get_task_cred(tracer);
+		tracerp = aa_cred_profile(cred);
+	}
+	rcu_read_unlock();
+
+	/* not ptraced */
+	if (!tracer || unconfined(tracerp))
+		goto out;
+
+	error = aa_may_ptrace(tracer, tracerp, to_profile, PTRACE_MODE_ATTACH);
+
+out:
+	if (cred)
+		put_cred(cred);
+
+	return error;
+}
+
+/**
+ * change_profile_perms - find permissions for change_profile
+ * @profile: the current profile  (NOT NULL)
+ * @ns: the namespace being switched to  (NOT NULL)
+ * @name: the name of the profile to change to  (NOT NULL)
+ * @request: requested perms
+ * @start: state to start matching in
+ *
+ * Returns: permission set
+ */
+static struct file_perms change_profile_perms(struct aa_profile *profile,
+					      struct aa_namespace *ns,
+					      const char *name, u32 request,
+					      unsigned int start)
+{
+	struct file_perms perms;
+	struct path_cond cond = { };
+	unsigned int state;
+
+	if (unconfined(profile)) {
+		perms.allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC;
+		perms.audit = perms.quiet = perms.kill = 0;
+		return perms;
+	} else if (!profile->file.dfa) {
+		return nullperms;
+	} else if ((ns == profile->ns)) {
+		/* try matching against rules with out namespace prepended */
+		aa_str_perms(profile->file.dfa, start, name, &cond, &perms);
+		if (COMBINED_PERM_MASK(perms) & request)
+			return perms;
+	}
+
+	/* try matching with namespace name and then profile */
+	state = aa_dfa_match(profile->file.dfa, start, ns->base.name);
+	state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
+	aa_str_perms(profile->file.dfa, state, name, &cond, &perms);
+
+	return perms;
+}
+
+/**
+ * __attach_match_ - find an attachment match
+ * @name - to match against  (NOT NULL)
+ * @head - profile list to walk  (NOT NULL)
+ *
+ * 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
+ */
+static struct aa_profile *__attach_match(const char *name,
+					 struct list_head *head)
+{
+	int len = 0;
+	struct aa_profile *profile, *candidate = NULL;
+
+	list_for_each_entry(profile, head, base.list) {
+		if (profile->flags & PFLAG_NULL)
+			continue;
+		if (profile->xmatch && profile->xmatch_len > len) {
+			unsigned int state = aa_dfa_match(profile->xmatch,
+							  DFA_START, name);
+			u32 perm = dfa_user_allow(profile->xmatch, state);
+			/* any accepting state means a valid match. */
+			if (perm & MAY_EXEC) {
+				candidate = profile;
+				len = profile->xmatch_len;
+			}
+		} else if (!strcmp(profile->base.name, name))
+			/* exact non-re match, no more searching required */
+			return profile;
+	}
+
+	return candidate;
+}
+
+/**
+ * find_attach - do attachment search for unconfined processes
+ * @ns: the current namespace  (NOT NULL)
+ * @list: list to search  (NOT NULL)
+ * @name: the executable name to match against  (NOT NULL)
+ *
+ * Returns: profile or NULL if no match found
+ */
+static struct aa_profile *find_attach(struct aa_namespace *ns,
+				      struct list_head *list, const char *name)
+{
+	struct aa_profile *profile;
+
+	read_lock(&ns->lock);
+	profile = aa_get_profile(__attach_match(name, list));
+	read_unlock(&ns->lock);
+
+	return profile;
+}
+
+/**
+ * separate_fqname - separate the namespace and profile names
+ * @fqname: the fqname name to split  (NOT NULL)
+ * @ns_name: the namespace name if it exists  (NOT NULL)
+ *
+ * This is the xtable equivalent routine of aa_split_fqname.  It finds the
+ * split in an xtable fqname which contains an embedded \0 instead of a :
+ * if a namespace is specified.  This is done so the xtable is constant and
+ * isn't re-split on every lookup.
+ *
+ * Either the profile or namespace name may be optional but if the namespace
+ * is specified the profile name termination must be present.  This results
+ * in the following possible encodings:
+ * profile_name\0
+ * :ns_name\0profile_name\0
+ * :ns_name\0\0
+ *
+ * NOTE: the xtable fqname is pre-validated at load time in unpack_trans_table
+ *
+ * Returns: profile name if it is specified else NULL
+ */
+static const char *separate_fqname(const char *fqname, const char **ns_name)
+{
+	const char *name;
+
+	if (fqname[0] == ':') {
+		/* In this case there is guaranteed to be two \0 terminators
+		 * in the string.  They are verified at load time by
+		 * by unpack_trans_table
+		 */
+		*ns_name = fqname + 1;		/* skip : */
+		name = *ns_name + strlen(*ns_name) + 1;
+		if (!*name)
+			name = NULL;
+	} else {
+		*ns_name = NULL;
+		name = fqname;
+	}
+
+	return name;
+}
+
+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
+ *
+ * Returns: refcounted profile, or NULL on failure (MAYBE NULL)
+ */
+static struct aa_profile *x_table_lookup(struct aa_profile *profile, u32 xindex)
+{
+	struct aa_profile *new_profile = NULL;
+	struct aa_namespace *ns = profile->ns;
+	u32 xtype = xindex & AA_X_TYPE_MASK;
+	int index = xindex & AA_X_INDEX_MASK;
+	const char *name;
+
+	/* index is guaranteed to be in range, validated at load time */
+	for (name = profile->file.trans.table[index]; !new_profile && name;
+	     name = next_name(xtype, name)) {
+		struct aa_namespace *new_ns;
+		const char *xname = NULL;
+
+		new_ns = NULL;
+		if (xindex & AA_X_CHILD) {
+			/* release by caller */
+			new_profile = aa_find_child(profile, name);
+			continue;
+		} else if (*name == ':') {
+			/* switching namespace */
+			const char *ns_name;
+			xname = name = separate_fqname(name, &ns_name);
+			if (!xname)
+				/* no name so use profile name */
+				xname = profile->base.hname;
+			if (*ns_name == '@') {
+				/* TODO: variable support */
+				;
+			}
+			/* released below */
+			new_ns = aa_find_namespace(ns, ns_name);
+			if (!new_ns)
+				continue;
+		} else if (*name == '@') {
+			/* TODO: variable support */
+			continue;
+		} else {
+			/* basic namespace lookup */
+			xname = name;
+		}
+
+		/* released by caller */
+		new_profile = aa_lookup_profile(new_ns ? new_ns : ns, xname);
+		aa_put_namespace(new_ns);
+	}
+
+	/* released by caller */
+	return new_profile;
+}
+
+/**
+ * x_to_profile - get target profile for a given xindex
+ * @profile: current profile  (NOT NULL)
+ * @name: name to lookup (NOT NULL)
+ * @xindex: index into x transition table
+ *
+ * find profile for a transition index
+ *
+ * Returns: refcounted profile or NULL if not found available
+ */
+static struct aa_profile *x_to_profile(struct aa_profile *profile,
+				       const char *name, u32 xindex)
+{
+	struct aa_profile *new_profile = NULL;
+	struct aa_namespace *ns = profile->ns;
+	u32 xtype = xindex & AA_X_TYPE_MASK;
+
+	switch (xtype) {
+	case AA_X_NONE:
+		/* fail exec unless ix || ux fallback - handled by caller */
+		return NULL;
+	case AA_X_NAME:
+		if (xindex & AA_X_CHILD)
+			/* released by caller */
+			new_profile = find_attach(ns, &profile->base.profiles,
+						  name);
+		else
+			/* released by caller */
+			new_profile = find_attach(ns, &ns->base.profiles,
+						  name);
+		break;
+	case AA_X_TABLE:
+		/* released by caller */
+		new_profile = x_table_lookup(profile, xindex);
+		break;
+	}
+
+	/* released by caller */
+	return new_profile;
+}
+
+/**
+ * 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
+ */
+int apparmor_bprm_set_creds(struct linux_binprm *bprm)
+{
+	struct aa_task_cxt *cxt;
+	struct aa_profile *profile, *new_profile = NULL;
+	struct aa_namespace *ns;
+	char *buffer = NULL;
+	unsigned int state;
+	struct file_perms perms = {};
+	struct path_cond cond = {
+		bprm->file->f_path.dentry->d_inode->i_uid,
+		bprm->file->f_path.dentry->d_inode->i_mode
+	};
+	const char *name = NULL, *target = NULL, *info = NULL;
+	int error = cap_bprm_set_creds(bprm);
+	if (error)
+		return error;
+
+	if (bprm->cred_prepared)
+		return 0;
+
+	cxt = bprm->cred->security;
+	BUG_ON(!cxt);
+
+	profile = aa_get_profile(aa_newest_version(cxt->profile));
+	/*
+	 * get the namespace from the replacement profile as replacement
+	 * can change the namespace
+	 */
+	ns = profile->ns;
+	state = profile->file.start;
+
+	/* buffer freed below, name is pointer into buffer */
+	error = aa_get_name(&bprm->file->f_path, profile->path_flags, &buffer,
+			    &name);
+	if (error) {
+		if (profile->flags &
+		    (PFLAG_IX_ON_NAME_ERROR | PFLAG_UNCONFINED))
+			error = 0;
+		info = "Exec failed name resolution";
+		name = bprm->filename;
+		goto audit;
+	}
+
+	/* Test for onexec first as onexec directives override other
+	 * x transitions.
+	 */
+	if (unconfined(profile)) {
+		/* unconfined task */
+		if (cxt->onexec)
+			/* change_profile on exec already been granted */
+			new_profile = aa_get_profile(cxt->onexec);
+		else
+			new_profile = find_attach(ns, &ns->base.profiles, name);
+		if (!new_profile)
+			goto cleanup;
+		goto apply;
+	}
+
+	/* find exec permissions for name */
+	state = aa_str_perms(profile->file.dfa, state, name, &cond, &perms);
+	if (cxt->onexec) {
+		struct file_perms cp;
+		info = "change_profile onexec";
+		if (!(perms.allow & AA_MAY_ONEXEC))
+			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);
+		cp = change_profile_perms(profile, cxt->onexec->ns, name,
+					  AA_MAY_ONEXEC, state);
+
+		if (!(cp.allow & AA_MAY_ONEXEC))
+			goto audit;
+		new_profile = aa_get_profile(aa_newest_version(cxt->onexec));
+		goto apply;
+	}
+
+	if (perms.allow & MAY_EXEC) {
+		/* exec permission determine how to transition */
+		new_profile = x_to_profile(profile, name, perms.xindex);
+		if (!new_profile) {
+			if (perms.xindex & AA_X_INHERIT) {
+				/* (p|c|n)ix - don't change profile but do
+				 * use the newest version, which was picked
+				 * up above when getting profile
+				 */
+				info = "ix fallback";
+				new_profile = aa_get_profile(profile);
+				goto x_clear;
+			} else if (perms.xindex & AA_X_UNCONFINED) {
+				new_profile = aa_get_profile(ns->unconfined);
+				info = "ux fallback";
+			} else {
+				error = -ENOENT;
+				info = "profile not found";
+			}
+		}
+	} else if (COMPLAIN_MODE(profile)) {
+		/* no exec permission - are we in learning mode */
+		new_profile = aa_new_null_profile(profile, 0);
+		if (!new_profile) {
+			error = -ENOMEM;
+			info = "could not create null profile";
+		} else {
+			error = -EACCES;
+			target = new_profile->base.hname;
+		}
+		perms.xindex |= AA_X_UNSAFE;
+	} else
+		/* fail exec */
+		error = -EACCES;
+
+	if (!new_profile)
+		goto audit;
+
+	if (bprm->unsafe & LSM_UNSAFE_SHARE) {
+		/* FIXME: currently don't mediate shared state */
+		;
+	}
+
+	if (bprm->unsafe & (LSM_UNSAFE_PTRACE | LSM_UNSAFE_PTRACE_CAP)) {
+		error = may_change_ptraced_domain(current, new_profile);
+		if (error) {
+			aa_put_profile(new_profile);
+			goto audit;
+		}
+	}
+
+	/* Determine if secure exec is needed.
+	 * Can be at this point for the following reasons:
+	 * 1. unconfined switching to confined
+	 * 2. confined switching to different confinement
+	 * 3. confined switching to unconfined
+	 *
+	 * Cases 2 and 3 are marked as requiring secure exec
+	 * (unless policy specified "unsafe exec")
+	 *
+	 * bprm->unsafe is used to cache the AA_X_UNSAFE permission
+	 * to avoid having to recompute in secureexec
+	 */
+	if (!(perms.xindex & AA_X_UNSAFE)) {
+		AA_DEBUG("scrubbing environment variables for %s profile=%s\n",
+			 name, new_profile->base.hname);
+		bprm->unsafe |= AA_SECURE_X_NEEDED;
+	}
+apply:
+	target = new_profile->base.hname;
+	/* when transitioning profiles clear unsafe personality bits */
+	bprm->per_clear |= PER_CLEAR_ON_SETID;
+
+x_clear:
+	aa_put_profile(cxt->profile);
+	/* transfer new profile reference will be released when cxt is freed */
+	cxt->profile = new_profile;
+
+	/* clear out all temporary/transitional state from the context */
+	aa_put_profile(cxt->previous);
+	aa_put_profile(cxt->onexec);
+	cxt->previous = NULL;
+	cxt->onexec = NULL;
+	cxt->token = 0;
+
+audit:
+	error = aa_audit_file(profile, &perms, GFP_KERNEL, OP_EXEC, MAY_EXEC,
+			      name, target, cond.uid, info, error);
+
+cleanup:
+	aa_put_profile(profile);
+	kfree(buffer);
+
+	return error;
+}
+
+/**
+ * apparmor_bprm_secureexec - determine if secureexec is needed
+ * @bprm: binprm for exec  (NOT NULL)
+ *
+ * Returns: %1 if secureexec is needed else %0
+ */
+int apparmor_bprm_secureexec(struct linux_binprm *bprm)
+{
+	int ret = cap_bprm_secureexec(bprm);
+
+	/* the decision to use secure exec is computed in set_creds
+	 * and stored in bprm->unsafe.
+	 */
+	if (!ret && (bprm->unsafe & AA_SECURE_X_NEEDED))
+		ret = 1;
+
+	return ret;
+}
+
+/**
+ * apparmor_bprm_committing_creds - do task cleanup on committing new creds
+ * @bprm: binprm for the exec  (NOT NULL)
+ */
+void apparmor_bprm_committing_creds(struct linux_binprm *bprm)
+{
+	struct aa_profile *profile = __aa_current_profile();
+	struct aa_task_cxt *new_cxt = bprm->cred->security;
+
+	/* bail out if unconfined or not changing profile */
+	if ((new_cxt->profile == profile) ||
+	    (unconfined(new_cxt->profile)))
+		return;
+
+	current->pdeath_signal = 0;
+
+	/* reset soft limits and set hard limits for the new profile */
+	__aa_transition_rlimits(profile, new_cxt->profile);
+}
+
+/**
+ * apparmor_bprm_commited_cred - do cleanup after new creds committed
+ * @bprm: binprm for the exec  (NOT NULL)
+ */
+void apparmor_bprm_committed_creds(struct linux_binprm *bprm)
+{
+	/* TODO: cleanup signals - ipc mediation */
+	return;
+}
+
+/*
+ * Functions for self directed profile change
+ */
+
+/**
+ * new_compound_name - create an hname with @n2 appended to @n1
+ * @n1: base of hname  (NOT NULL)
+ * @n2: name to append (NOT NULL)
+ *
+ * Returns: new name or NULL on error
+ */
+static char *new_compound_name(const char *n1, const char *n2)
+{
+	char *name = kmalloc(strlen(n1) + strlen(n2) + 3, GFP_KERNEL);
+	if (name)
+		sprintf(name, "%s//%s", n1, n2);
+	return name;
+}
+
+/**
+ * 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
+ * @permtest: true if this is just a permission test
+ *
+ * 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.
+ *
+ * Returns %0 on success, error otherwise.
+ */
+int aa_change_hat(const char *hats[], int count, u64 token, bool permtest)
+{
+	const struct cred *cred;
+	struct aa_task_cxt *cxt;
+	struct aa_profile *profile, *previous_profile, *hat = NULL;
+	char *name = NULL;
+	int i;
+	struct file_perms perms = {};
+	const char *target = NULL, *info = NULL;
+	int error = 0;
+
+	/* released below */
+	cred = get_current_cred();
+	cxt = cred->security;
+	profile = aa_cred_profile(cred);
+	previous_profile = cxt->previous;
+
+	if (unconfined(profile)) {
+		info = "unconfined";
+		error = -EPERM;
+		goto audit;
+	}
+
+	if (count) {
+		/* attempting to change into a new hat or switch to a sibling */
+		struct aa_profile *root;
+		root = PROFILE_IS_HAT(profile) ? profile->parent : profile;
+
+		/* find first matching hat */
+		for (i = 0; i < count && !hat; i++)
+			/* released below */
+			hat = aa_find_child(root, hats[i]);
+		if (!hat) {
+			if (!COMPLAIN_MODE(root) || permtest) {
+				if (list_empty(&root->base.profiles))
+					error = -ECHILD;
+				else
+					error = -ENOENT;
+				goto out;
+			}
+
+			/*
+			 * In complain mode and failed to match any hats.
+			 * Audit the failure is based off of the first hat
+			 * supplied.  This is done due how userspace
+			 * interacts with change_hat.
+			 *
+			 * TODO: Add logging of all failed hats
+			 */
+
+			/* freed below */
+			name = new_compound_name(root->base.hname, hats[0]);
+			target = name;
+			/* released below */
+			hat = aa_new_null_profile(profile, 1);
+			if (!hat) {
+				info = "failed null profile create";
+				error = -ENOMEM;
+				goto audit;
+			}
+		} else {
+			target = hat->base.hname;
+			if (!PROFILE_IS_HAT(hat)) {
+				info = "target not hat";
+				error = -EPERM;
+				goto audit;
+			}
+		}
+
+		error = may_change_ptraced_domain(current, hat);
+		if (error) {
+			info = "ptraced";
+			error = -EPERM;
+			goto audit;
+		}
+
+		if (!permtest) {
+			error = aa_set_current_hat(hat, token);
+			if (error == -EACCES)
+				/* kill task in case of brute force attacks */
+				perms.kill = AA_MAY_CHANGEHAT;
+			else if (name && !error)
+				/* reset error for learning of new hats */
+				error = -ENOENT;
+		}
+	} else if (previous_profile) {
+		/* Return to saved profile.  Kill task if restore fails
+		 * to avoid brute force attacks
+		 */
+		target = previous_profile->base.hname;
+		error = aa_restore_previous_profile(token);
+		perms.kill = AA_MAY_CHANGEHAT;
+	} else
+		/* ignore restores when there is no saved profile */
+		goto out;
+
+audit:
+	if (!permtest)
+		error = aa_audit_file(profile, &perms, GFP_KERNEL,
+				      OP_CHANGE_HAT, AA_MAY_CHANGEHAT, NULL,
+				      target, 0, info, error);
+
+out:
+	aa_put_profile(hat);
+	kfree(name);
+	put_cred(cred);
+
+	return error;
+}
+
+/**
+ * aa_change_profile - perform a one-way profile transition
+ * @ns_name: name of the profile namespace to change to (MAYBE NULL)
+ * @hname: name of profile to change to (MAYBE NULL)
+ * @onexec: whether this transition is to take place immediately or at exec
+ * @permtest: true if this is just a permission test
+ *
+ * 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.
+ */
+int aa_change_profile(const char *ns_name, const char *hname, bool onexec,
+		      bool permtest)
+{
+	const struct cred *cred;
+	struct aa_task_cxt *cxt;
+	struct aa_profile *profile, *target = NULL;
+	struct aa_namespace *ns = NULL;
+	struct file_perms perms = {};
+	const char *name = NULL, *info = NULL;
+	int op, error = 0;
+	u32 request;
+
+	if (!hname && !ns_name)
+		return -EINVAL;
+
+	if (onexec) {
+		request = AA_MAY_ONEXEC;
+		op = OP_CHANGE_ONEXEC;
+	} else {
+		request = AA_MAY_CHANGE_PROFILE;
+		op = OP_CHANGE_PROFILE;
+	}
+
+	cred = get_current_cred();
+	cxt = cred->security;
+	profile = aa_cred_profile(cred);
+
+	if (ns_name) {
+		/* released below */
+		ns = aa_find_namespace(profile->ns, ns_name);
+		if (!ns) {
+			/* we don't create new namespace in complain mode */
+			name = ns_name;
+			info = "namespace not found";
+			error = -ENOENT;
+			goto audit;
+		}
+	} else
+		/* released below */
+		ns = aa_get_namespace(profile->ns);
+
+	/* if the name was not specified, use the name of the current profile */
+	if (!hname) {
+		if (unconfined(profile))
+			hname = ns->unconfined->base.hname;
+		else
+			hname = profile->base.hname;
+	}
+
+	perms = change_profile_perms(profile, ns, hname, request,
+				     profile->file.start);
+	if (!(perms.allow & request)) {
+		error = -EACCES;
+		goto audit;
+	}
+
+	/* released below */
+	target = aa_lookup_profile(ns, hname);
+	if (!target) {
+		info = "profile not found";
+		error = -ENOENT;
+		if (permtest || !COMPLAIN_MODE(profile))
+			goto audit;
+		/* released below */
+		target = aa_new_null_profile(profile, 0);
+		if (!target) {
+			info = "failed null profile create";
+			error = -ENOMEM;
+			goto audit;
+		}
+	}
+
+	/* check if tracing task is allowed to trace target domain */
+	error = may_change_ptraced_domain(current, target);
+	if (error) {
+		info = "ptrace prevents transition";
+		goto audit;
+	}
+
+	if (permtest)
+		goto audit;
+
+	if (onexec)
+		error = aa_set_current_onexec(target);
+	else
+		error = aa_replace_current_profile(target);
+
+audit:
+	if (!permtest)
+		error = aa_audit_file(profile, &perms, GFP_KERNEL, op, request,
+				      name, hname, 0, info, error);
+
+	aa_put_namespace(ns);
+	aa_put_profile(target);
+	put_cred(cred);
+
+	return error;
+}

security/apparmor/include/domain.h

+/*
+ * AppArmor security module
+ *
+ * This file contains AppArmor security domain transition function definitions.
+ *
+ * Copyright (C) 1998-2008 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/binfmts.h>
+#include <linux/types.h>
+
+#ifndef __AA_DOMAIN_H
+#define __AA_DOMAIN_H
+
+struct aa_domain {
+	int size;
+	char **table;
+};
+
+int apparmor_bprm_set_creds(struct linux_binprm *bprm);
+int apparmor_bprm_secureexec(struct linux_binprm *bprm);
+void apparmor_bprm_committing_creds(struct linux_binprm *bprm);
+void apparmor_bprm_committed_creds(struct linux_binprm *bprm);
+
+void aa_free_domain_entries(struct aa_domain *domain);
+int aa_change_hat(const char *hats[], int count, u64 token, bool permtest);
+int aa_change_profile(const char *ns_name, const char *name, bool onexec,
+		      bool permtest);
+
+#endif /* __AA_DOMAIN_H */