apparmor: move exec domain mediation to using labels

Signed-off-by: John Johansen <john.johansen@canonical.com>

security/apparmor/domain.c

@@ -87,42 +87,236 @@ static int may_change_ptraced_domain(struct aa_label *to_label,
 	return error;
 }
 
+/**** 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 *****/
+
 /**
  * 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)
+ * @target: label to transition to (NOT NULL)
+ * @stack: whether this is a stacking request
  * @request: requested perms
  * @start: state to start matching in
  *
+ *
  * Returns: permission set
+ *
+ * currently only matches full label A//&B//&C or individual components A, B, C
+ * not arbitrary combinations. Eg. A//&B, C
  */
-static struct aa_perms change_profile_perms(struct aa_profile *profile,
-					    struct aa_ns *ns,
-					    const char *name, u32 request,
-					    unsigned int start)
+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);
+}
+
+static struct aa_perms change_profile_perms_wrapper(struct aa_profile *profile,
+						    struct aa_profile *target,
+						    u32 request,
+						    unsigned int start)
 {
 	struct aa_perms perms;
-	struct path_cond cond = { };
-	unsigned int state;
 
 	if (profile_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);
+	if (change_profile_perms(profile, &target->label, false, request,
+				 start, &perms))
+		return nullperms;
 
 	return perms;
 }
@@ -173,10 +367,10 @@ static struct aa_profile *__attach_match(const char *name,
  * @list: list to search  (NOT NULL)
  * @name: the executable name to match against  (NOT NULL)
  *
- * Returns: profile or NULL if no match found
+ * Returns: label or NULL if no match found
  */
-static struct aa_profile *find_attach(struct aa_ns *ns,
-				      struct list_head *list, const char *name)
+static struct aa_label *find_attach(struct aa_ns *ns, struct list_head *list,
+				    const char *name)
 {
 	struct aa_profile *profile;
 
@@ -184,49 +378,7 @@ static struct aa_profile *find_attach(struct aa_ns *ns,
 	profile = aa_get_profile(__attach_match(name, list));
 	rcu_read_unlock();
 
-	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;
+	return profile ? &profile->label : NULL;
 }
 
 static const char *next_name(int xtype, const char *name)
@@ -238,295 +390,477 @@ static const char *next_name(int xtype, const char *name)
  * x_table_lookup - lookup an x transition name via transition table
  * @profile: current profile (NOT NULL)
  * @xindex: index into x transition table
+ * @name: returns: name tested to find label (NOT NULL)
  *
- * Returns: refcounted profile, or NULL on failure (MAYBE NULL)
+ * Returns: refcounted label, or NULL on failure (MAYBE NULL)
  */
-static struct aa_profile *x_table_lookup(struct aa_profile *profile, u32 xindex)
+static struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
+				       const char **name)
 {
-	struct aa_profile *new_profile = NULL;
-	struct aa_ns *ns = profile->ns;
+	struct aa_label *label = NULL;
 	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_ns *new_ns;
-		const char *xname = NULL;
+	AA_BUG(!name);
 
-		new_ns = NULL;
+	/* 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)) {
 		if (xindex & AA_X_CHILD) {
+			struct aa_profile *new_profile;
 			/* release by caller */
-			new_profile = aa_find_child(profile, name);
+			new_profile = aa_find_child(profile, *name);
+			if (new_profile)
+				label = &new_profile->label;
 			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_ns(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_ns(new_ns);
+		label = aa_label_parse(&profile->label, *name, GFP_ATOMIC,
+				       true, false);
+		if (IS_ERR(label))
+			label = NULL;
 	}
 
 	/* released by caller */
-	return new_profile;
+
+	return label;
 }
 
 /**
- * x_to_profile - get target profile for a given xindex
+ * x_to_label - get target label for a given xindex
  * @profile: current profile  (NOT NULL)
  * @name: name to lookup (NOT NULL)
  * @xindex: index into x transition table
+ * @lookupname: returns: name used in lookup if one was specified (NOT NULL)
  *
- * find profile for a transition index
+ * find label for a transition index
  *
- * Returns: refcounted profile or NULL if not found available
+ * Returns: refcounted label or NULL if not found available
  */
-static struct aa_profile *x_to_profile(struct aa_profile *profile,
-				       const char *name, u32 xindex)
+static struct aa_label *x_to_label(struct aa_profile *profile,
+				   const char *name, u32 xindex,
+				   const char **lookupname,
+				   const char **info)
 {
-	struct aa_profile *new_profile = NULL;
+	struct aa_label *new = NULL;
 	struct aa_ns *ns = profile->ns;
 	u32 xtype = xindex & AA_X_TYPE_MASK;
+	const char *stack = NULL;
 
 	switch (xtype) {
 	case AA_X_NONE:
 		/* fail exec unless ix || ux fallback - handled by caller */
-		return NULL;
+		*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 */
 	case AA_X_NAME:
 		if (xindex & AA_X_CHILD)
 			/* released by caller */
-			new_profile = find_attach(ns, &profile->base.profiles,
-						  name);
+			new = 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);
+			new = find_attach(ns, &ns->base.profiles,
+						name);
+		*lookupname = name;
 		break;
 	}
 
+	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);
+	}
+
 	/* released by caller */
-	return new_profile;
+	return new;
 }
 
-/**
- * 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)
+static struct aa_label *profile_transition(struct aa_profile *profile,
+					   const struct linux_binprm *bprm,
+					   char *buffer, struct path_cond *cond,
+					   bool *secure_exec)
 {
-	struct aa_task_ctx *ctx;
-	struct aa_label *label;
-	struct aa_profile *profile, *new_profile = NULL;
-	struct aa_ns *ns;
-	char *buffer = NULL;
-	unsigned int state;
+	struct aa_label *new = NULL;
+	const char *info = NULL, *name = NULL, *target = NULL;
+	unsigned int state = profile->file.start;
 	struct aa_perms perms = {};
-	struct path_cond cond = {
-		file_inode(bprm->file)->i_uid,
-		file_inode(bprm->file)->i_mode
-	};
-	const char *name = NULL, *info = NULL;
+	bool nonewprivs = false;
 	int error = 0;
 
-	if (bprm->cred_prepared)
-		return 0;
-
-	ctx = cred_ctx(bprm->cred);
-	AA_BUG(!ctx);
-
-	label = aa_get_newest_label(ctx->label);
-	profile = labels_profile(label);
-
-	/* buffer freed below, name is pointer into buffer */
-	get_buffers(buffer);
-	/*
-	 * get the namespace from the replacement profile as replacement
-	 * can change the namespace
-	 */
-	ns = profile->ns;
-	state = profile->file.start;
+	AA_BUG(!profile);
+	AA_BUG(!bprm);
+	AA_BUG(!buffer);
 
 	error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
 			     &name, &info, profile->disconnected);
 	if (error) {
 		if (profile_unconfined(profile) ||
-		    (profile->label.flags & FLAG_IX_ON_NAME_ERROR))
+		    (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
+			AA_DEBUG("name lookup ix on error");
 			error = 0;
+			new = aa_get_newest_label(&profile->label);
+		}
 		name = bprm->filename;
 		goto audit;
 	}
 
-	/* Test for onexec first as onexec directives override other
-	 * x transitions.
-	 */
 	if (profile_unconfined(profile)) {
-		/* unconfined task */
-		if (ctx->onexec)
-			/* change_profile on exec already been granted */
-			new_profile = labels_profile(aa_get_label(ctx->onexec));
-		else
-			new_profile = find_attach(ns, &ns->base.profiles, name);
-		if (!new_profile)
-			goto cleanup;
-		/*
-		 * NOTE: Domain transitions from unconfined are allowed
-		 * even when no_new_privs is set because this aways results
-		 * in a further reduction of permissions.
-		 */
-		goto apply;
+		new = find_attach(profile->ns, &profile->ns->base.profiles,
+				  name);
+		if (new) {
+			AA_DEBUG("unconfined attached to new label");
+			return new;
+		}
+		AA_DEBUG("unconfined exec no attachment");
+		return aa_get_newest_label(&profile->label);
 	}
 
 	/* find exec permissions for name */
-	state = aa_str_perms(profile->file.dfa, state, name, &cond, &perms);
-	if (ctx->onexec) {
-		struct aa_perms cp;
-		info = "change_profile onexec";
-		new_profile = labels_profile(aa_get_newest_label(ctx->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, labels_ns(ctx->onexec),
-				labels_profile(ctx->onexec)->base.name,
-				AA_MAY_ONEXEC, state);
-
-		if (!(cp.allow & AA_MAY_ONEXEC))
-			goto audit;
-		goto apply;
-	}
-
+	state = aa_str_perms(profile->file.dfa, state, name, cond, &perms);
 	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_newest_profile(ns->unconfined);
-				info = "ux fallback";
-			} else {
-				error = -EACCES;
-				info = "profile not found";
-				/* remove MAY_EXEC to audit as failure */
-				perms.allow &= ~MAY_EXEC;
-			}
+		new = x_to_label(profile, name, perms.xindex, &target, &info);
+		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;
 		}
 	} else if (COMPLAIN_MODE(profile)) {
-		/* no exec permission - are we in learning mode */
-		new_profile = aa_new_null_profile(profile, false, name,
-						  GFP_ATOMIC);
+		/* no exec permission - learning mode */
+		struct aa_profile *new_profile = aa_new_null_profile(profile,
+							      false, name,
+							      GFP_ATOMIC);
 		if (!new_profile) {
 			error = -ENOMEM;
 			info = "could not create null profile";
-		} else
+		} else {
 			error = -EACCES;
+			new = &new_profile->label;
+		}
 		perms.xindex |= AA_X_UNSAFE;
 	} else
 		/* fail exec */
 		error = -EACCES;
 
-	/*
-	 * Policy has specified a domain transition, if no_new_privs then
-	 * fail the exec.
+	if (!new)
+		goto audit;
+
+	/* Policy has specified a domain transitions. if no_new_privs and
+	 * confined and not transitioning to the current domain fail.
+	 *
+	 * NOTE: Domain transitions from unconfined and to stritly 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) {
+	if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) &&
+	    !profile_unconfined(profile) &&
+	    !aa_label_is_subset(new, &profile->label)) {
 		error = -EPERM;
-		goto cleanup;
+		info = "no new privs";
+		nonewprivs = true;
+		perms.allow &= ~MAY_EXEC;
+		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;
 	}
 
-	if (!new_profile)
+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;
 		goto audit;
+	}
+
+	/* 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;
+	}
+	/* Policy has specified a domain transitions. if no_new_privs and
+	 * confined and not transitioning to the current domain fail.
+	 *
+	 * NOTE: Domain transitions from unconfined and to stritly 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) &&
+	    !profile_unconfined(profile) &&
+	    !aa_label_is_subset(onexec, &profile->label)) {
+		error = -EPERM;
+		info = "no new privs";
+		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)
+{
+	struct aa_task_ctx *ctx;
+	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
+	};
+
+	if (bprm->cred_prepared)
+		return 0;
+
+	ctx = cred_ctx(bprm->cred);
+	AA_BUG(!ctx);
+
+	label = aa_get_newest_label(ctx->label);
+
+	/* buffer freed below, name is pointer into buffer */
+	get_buffers(buffer);
+	/* Test for onexec first as onexec override other x transitions. */
+	if (ctx->onexec)
+		new = handle_onexec(label, ctx->onexec, ctx->token,
+				    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;
+	}
+
+	/* TODO: Add ns level no_new_privs subset test */
 
 	if (bprm->unsafe & LSM_UNSAFE_SHARE) {
 		/* FIXME: currently don't mediate shared state */
 		;
 	}
 
-	if (bprm->unsafe & LSM_UNSAFE_PTRACE) {
-		error = may_change_ptraced_domain(&new_profile->label, &info);
+	if (bprm->unsafe & (LSM_UNSAFE_PTRACE)) {
+		/* TODO: test needs to be profile of label to new */
+		error = may_change_ptraced_domain(new, &info);
 		if (error)
 			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);
+	if (unsafe) {
+		if (DEBUG_ON) {
+			dbg_printk("scrubbing environment variables for %s "
+				   "label=", bprm->filename);
+			aa_label_printk(new, GFP_ATOMIC);
+			dbg_printk("\n");
+		}
 		bprm->unsafe |= AA_SECURE_X_NEEDED;
 	}
-apply:
-	/* when transitioning profiles clear unsafe personality bits */
-	bprm->per_clear |= PER_CLEAR_ON_SETID;
 
-x_clear:
+	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;
+	}
 	aa_put_label(ctx->label);
-	/* transfer new profile reference will be released when ctx is freed */
-	ctx->label = &new_profile->label;
-	new_profile = NULL;
+	/* transfer reference, released when ctx is freed */
+	ctx->label = new;
 
-	/* clear out all temporary/transitional state from the context */
+done:
+	/* clear out temporary/transitional state from the context */
 	aa_clear_task_ctx_trans(ctx);
 
-audit:
-	error = aa_audit_file(profile, &perms, OP_EXEC, MAY_EXEC, name,
-			      new_profile ? new_profile->base.hname : NULL,
-			      new_profile ? &new_profile->label : NULL,
-			      cond.uid, info, error);
-
-cleanup:
-	aa_put_profile(new_profile);
 	aa_put_label(label);
 	put_buffers(buffer);
 
 	return error;
+
+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;
 }
 
 /**
@@ -778,8 +1112,8 @@ int aa_change_profile(const char *fqname, int flags)
 		}
 	}
 
-	perms = change_profile_perms(profile, target->ns, target->base.hname,
-				     request, profile->file.start);
+	perms = change_profile_perms_wrapper(profile, target, request,
+					     profile->file.start);
 	if (!(perms.allow & request)) {
 		error = -EACCES;
 		goto audit;

security/apparmor/include/lib.h

@@ -211,4 +211,89 @@ bool aa_policy_init(struct aa_policy *policy, const char *prefix,
 		    const char *name, gfp_t gfp);
 void aa_policy_destroy(struct aa_policy *policy);
 
-#endif /* AA_LIB_H */
+
+/*
+ * fn_label_build - abstract out the build of a label transition
+ * @L: label the transition is being computed for
+ * @P: profile parameter derived from L by this macro, can be passed to FN
+ * @GFP: memory allocation type to use
+ * @FN: fn to call for each profile transition. @P is set to the profile
+ *
+ * Returns: new label on success
+ *          ERR_PTR if build @FN fails
+ *          NULL if label_build fails due to low memory conditions
+ *
+ * @FN must return a label or ERR_PTR on failure. NULL is not allowed
+ */
+#define fn_label_build(L, P, GFP, FN)					\
+({									\
+	__label__ __cleanup, __done;					\
+	struct aa_label *__new_;					\
+									\
+	if ((L)->size > 1) {						\
+		/* TODO: add cache of transitions already done */	\
+		struct label_it __i;					\
+		int __j, __k, __count;					\
+		DEFINE_VEC(label, __lvec);				\
+		DEFINE_VEC(profile, __pvec);				\
+		if (vec_setup(label, __lvec, (L)->size, (GFP)))	{	\
+			__new_ = NULL;					\
+			goto __done;					\
+		}							\
+		__j = 0;						\
+		label_for_each(__i, (L), (P)) {				\
+			__new_ = (FN);					\
+			AA_BUG(!__new_);				\
+			if (IS_ERR(__new_))				\
+				goto __cleanup;				\
+			__lvec[__j++] = __new_;				\
+		}							\
+		for (__j = __count = 0; __j < (L)->size; __j++)		\
+			__count += __lvec[__j]->size;			\
+		if (!vec_setup(profile, __pvec, __count, (GFP))) {	\
+			for (__j = __k = 0; __j < (L)->size; __j++) {	\
+				label_for_each(__i, __lvec[__j], (P))	\
+					__pvec[__k++] = aa_get_profile(P); \
+			}						\
+			__count -= aa_vec_unique(__pvec, __count, 0);	\
+			if (__count > 1) {				\
+				__new_ = aa_vec_find_or_create_label(__pvec,\
+						     __count, (GFP));	\
+				/* only fails if out of Mem */		\
+				if (!__new_)				\
+					__new_ = NULL;			\
+			} else						\
+				__new_ = aa_get_label(&__pvec[0]->label); \
+			vec_cleanup(profile, __pvec, __count);		\
+		} else							\
+			__new_ = NULL;					\
+__cleanup:								\
+		vec_cleanup(label, __lvec, (L)->size);			\
+	} else {							\
+		(P) = labels_profile(L);				\
+		__new_ = (FN);						\
+	}								\
+__done:									\
+	if (!__new_)							\
+		AA_DEBUG("label build failed\n");			\
+	(__new_);							\
+})
+
+
+#define __fn_build_in_ns(NS, P, NS_FN, OTHER_FN)			\
+({									\
+	struct aa_label *__new;						\
+	if ((P)->ns != (NS))						\
+		__new = (OTHER_FN);					\
+	else								\
+		__new = (NS_FN);					\
+	(__new);							\
+})
+
+#define fn_label_build_in_ns(L, P, GFP, NS_FN, OTHER_FN)		\
+({									\
+	fn_label_build((L), (P), (GFP),					\
+		__fn_build_in_ns(labels_ns(L), (P), (NS_FN), (OTHER_FN))); \
+})
+
+#endif /* __AA_LIB_H */