Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 945 insertions, 0 deletions

diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
new file mode 100644
index 000000000..31af29f66
--- /dev/null
+++ b/security/tomoyo/domain.c
@@ -0,0 +1,945 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * security/tomoyo/domain.c
+ *
+ * Copyright (C) 2005-2011  NTT DATA CORPORATION
+ */
+
+#include "common.h"
+
+#include <linux/binfmts.h>
+#include <linux/slab.h>
+#include <linux/rculist.h>
+
+/* Variables definitions.*/
+
+/* The initial domain. */
+struct tomoyo_domain_info tomoyo_kernel_domain;
+
+/**
+ * tomoyo_update_policy - Update an entry for exception policy.
+ *
+ * @new_entry:       Pointer to "struct tomoyo_acl_info".
+ * @size:            Size of @new_entry in bytes.
+ * @param:           Pointer to "struct tomoyo_acl_param".
+ * @check_duplicate: Callback function to find duplicated entry.
+ *
+ * Returns 0 on success, negative value otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+int tomoyo_update_policy(struct tomoyo_acl_head *new_entry, const int size,
+			 struct tomoyo_acl_param *param,
+			 bool (*check_duplicate)(const struct tomoyo_acl_head
+						 *,
+						 const struct tomoyo_acl_head
+						 *))
+{
+	int error = param->is_delete ? -ENOENT : -ENOMEM;
+	struct tomoyo_acl_head *entry;
+	struct list_head *list = param->list;
+
+	if (mutex_lock_interruptible(&tomoyo_policy_lock))
+		return -ENOMEM;
+	list_for_each_entry_rcu(entry, list, list,
+				srcu_read_lock_held(&tomoyo_ss)) {
+		if (entry->is_deleted == TOMOYO_GC_IN_PROGRESS)
+			continue;
+		if (!check_duplicate(entry, new_entry))
+			continue;
+		entry->is_deleted = param->is_delete;
+		error = 0;
+		break;
+	}
+	if (error && !param->is_delete) {
+		entry = tomoyo_commit_ok(new_entry, size);
+		if (entry) {
+			list_add_tail_rcu(&entry->list, list);
+			error = 0;
+		}
+	}
+	mutex_unlock(&tomoyo_policy_lock);
+	return error;
+}
+
+/**
+ * tomoyo_same_acl_head - Check for duplicated "struct tomoyo_acl_info" entry.
+ *
+ * @a: Pointer to "struct tomoyo_acl_info".
+ * @b: Pointer to "struct tomoyo_acl_info".
+ *
+ * Returns true if @a == @b, false otherwise.
+ */
+static inline bool tomoyo_same_acl_head(const struct tomoyo_acl_info *a,
+					const struct tomoyo_acl_info *b)
+{
+	return a->type == b->type && a->cond == b->cond;
+}
+
+/**
+ * tomoyo_update_domain - Update an entry for domain policy.
+ *
+ * @new_entry:       Pointer to "struct tomoyo_acl_info".
+ * @size:            Size of @new_entry in bytes.
+ * @param:           Pointer to "struct tomoyo_acl_param".
+ * @check_duplicate: Callback function to find duplicated entry.
+ * @merge_duplicate: Callback function to merge duplicated entry.
+ *
+ * Returns 0 on success, negative value otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+int tomoyo_update_domain(struct tomoyo_acl_info *new_entry, const int size,
+			 struct tomoyo_acl_param *param,
+			 bool (*check_duplicate)(const struct tomoyo_acl_info
+						 *,
+						 const struct tomoyo_acl_info
+						 *),
+			 bool (*merge_duplicate)(struct tomoyo_acl_info *,
+						 struct tomoyo_acl_info *,
+						 const bool))
+{
+	const bool is_delete = param->is_delete;
+	int error = is_delete ? -ENOENT : -ENOMEM;
+	struct tomoyo_acl_info *entry;
+	struct list_head * const list = param->list;
+
+	if (param->data[0]) {
+		new_entry->cond = tomoyo_get_condition(param);
+		if (!new_entry->cond)
+			return -EINVAL;
+		/*
+		 * Domain transition preference is allowed for only
+		 * "file execute" entries.
+		 */
+		if (new_entry->cond->transit &&
+		    !(new_entry->type == TOMOYO_TYPE_PATH_ACL &&
+		      container_of(new_entry, struct tomoyo_path_acl, head)
+		      ->perm == 1 << TOMOYO_TYPE_EXECUTE))
+			goto out;
+	}
+	if (mutex_lock_interruptible(&tomoyo_policy_lock))
+		goto out;
+	list_for_each_entry_rcu(entry, list, list,
+				srcu_read_lock_held(&tomoyo_ss)) {
+		if (entry->is_deleted == TOMOYO_GC_IN_PROGRESS)
+			continue;
+		if (!tomoyo_same_acl_head(entry, new_entry) ||
+		    !check_duplicate(entry, new_entry))
+			continue;
+		if (merge_duplicate)
+			entry->is_deleted = merge_duplicate(entry, new_entry,
+							    is_delete);
+		else
+			entry->is_deleted = is_delete;
+		error = 0;
+		break;
+	}
+	if (error && !is_delete) {
+		entry = tomoyo_commit_ok(new_entry, size);
+		if (entry) {
+			list_add_tail_rcu(&entry->list, list);
+			error = 0;
+		}
+	}
+	mutex_unlock(&tomoyo_policy_lock);
+out:
+	tomoyo_put_condition(new_entry->cond);
+	return error;
+}
+
+/**
+ * tomoyo_check_acl - Do permission check.
+ *
+ * @r:           Pointer to "struct tomoyo_request_info".
+ * @check_entry: Callback function to check type specific parameters.
+ *
+ * Returns 0 on success, negative value otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+void tomoyo_check_acl(struct tomoyo_request_info *r,
+		      bool (*check_entry)(struct tomoyo_request_info *,
+					  const struct tomoyo_acl_info *))
+{
+	const struct tomoyo_domain_info *domain = r->domain;
+	struct tomoyo_acl_info *ptr;
+	const struct list_head *list = &domain->acl_info_list;
+	u16 i = 0;
+
+retry:
+	list_for_each_entry_rcu(ptr, list, list,
+				srcu_read_lock_held(&tomoyo_ss)) {
+		if (ptr->is_deleted || ptr->type != r->param_type)
+			continue;
+		if (!check_entry(r, ptr))
+			continue;
+		if (!tomoyo_condition(r, ptr->cond))
+			continue;
+		r->matched_acl = ptr;
+		r->granted = true;
+		return;
+	}
+	for (; i < TOMOYO_MAX_ACL_GROUPS; i++) {
+		if (!test_bit(i, domain->group))
+			continue;
+		list = &domain->ns->acl_group[i++];
+		goto retry;
+	}
+	r->granted = false;
+}
+
+/* The list for "struct tomoyo_domain_info". */
+LIST_HEAD(tomoyo_domain_list);
+
+/**
+ * tomoyo_last_word - Get last component of a domainname.
+ *
+ * @name: Domainname to check.
+ *
+ * Returns the last word of @domainname.
+ */
+static const char *tomoyo_last_word(const char *name)
+{
+	const char *cp = strrchr(name, ' ');
+
+	if (cp)
+		return cp + 1;
+	return name;
+}
+
+/**
+ * tomoyo_same_transition_control - Check for duplicated "struct tomoyo_transition_control" entry.
+ *
+ * @a: Pointer to "struct tomoyo_acl_head".
+ * @b: Pointer to "struct tomoyo_acl_head".
+ *
+ * Returns true if @a == @b, false otherwise.
+ */
+static bool tomoyo_same_transition_control(const struct tomoyo_acl_head *a,
+					   const struct tomoyo_acl_head *b)
+{
+	const struct tomoyo_transition_control *p1 = container_of(a,
+								  typeof(*p1),
+								  head);
+	const struct tomoyo_transition_control *p2 = container_of(b,
+								  typeof(*p2),
+								  head);
+
+	return p1->type == p2->type && p1->is_last_name == p2->is_last_name
+		&& p1->domainname == p2->domainname
+		&& p1->program == p2->program;
+}
+
+/**
+ * tomoyo_write_transition_control - Write "struct tomoyo_transition_control" list.
+ *
+ * @param: Pointer to "struct tomoyo_acl_param".
+ * @type:  Type of this entry.
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+int tomoyo_write_transition_control(struct tomoyo_acl_param *param,
+				    const u8 type)
+{
+	struct tomoyo_transition_control e = { .type = type };
+	int error = param->is_delete ? -ENOENT : -ENOMEM;
+	char *program = param->data;
+	char *domainname = strstr(program, " from ");
+
+	if (domainname) {
+		*domainname = '\0';
+		domainname += 6;
+	} else if (type == TOMOYO_TRANSITION_CONTROL_NO_KEEP ||
+		   type == TOMOYO_TRANSITION_CONTROL_KEEP) {
+		domainname = program;
+		program = NULL;
+	}
+	if (program && strcmp(program, "any")) {
+		if (!tomoyo_correct_path(program))
+			return -EINVAL;
+		e.program = tomoyo_get_name(program);
+		if (!e.program)
+			goto out;
+	}
+	if (domainname && strcmp(domainname, "any")) {
+		if (!tomoyo_correct_domain(domainname)) {
+			if (!tomoyo_correct_path(domainname))
+				goto out;
+			e.is_last_name = true;
+		}
+		e.domainname = tomoyo_get_name(domainname);
+		if (!e.domainname)
+			goto out;
+	}
+	param->list = &param->ns->policy_list[TOMOYO_ID_TRANSITION_CONTROL];
+	error = tomoyo_update_policy(&e.head, sizeof(e), param,
+				     tomoyo_same_transition_control);
+out:
+	tomoyo_put_name(e.domainname);
+	tomoyo_put_name(e.program);
+	return error;
+}
+
+/**
+ * tomoyo_scan_transition - Try to find specific domain transition type.
+ *
+ * @list:       Pointer to "struct list_head".
+ * @domainname: The name of current domain.
+ * @program:    The name of requested program.
+ * @last_name:  The last component of @domainname.
+ * @type:       One of values in "enum tomoyo_transition_type".
+ *
+ * Returns true if found one, false otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+static inline bool tomoyo_scan_transition
+(const struct list_head *list, const struct tomoyo_path_info *domainname,
+ const struct tomoyo_path_info *program, const char *last_name,
+ const enum tomoyo_transition_type type)
+{
+	const struct tomoyo_transition_control *ptr;
+
+	list_for_each_entry_rcu(ptr, list, head.list,
+				srcu_read_lock_held(&tomoyo_ss)) {
+		if (ptr->head.is_deleted || ptr->type != type)
+			continue;
+		if (ptr->domainname) {
+			if (!ptr->is_last_name) {
+				if (ptr->domainname != domainname)
+					continue;
+			} else {
+				/*
+				 * Use direct strcmp() since this is
+				 * unlikely used.
+				 */
+				if (strcmp(ptr->domainname->name, last_name))
+					continue;
+			}
+		}
+		if (ptr->program && tomoyo_pathcmp(ptr->program, program))
+			continue;
+		return true;
+	}
+	return false;
+}
+
+/**
+ * tomoyo_transition_type - Get domain transition type.
+ *
+ * @ns:         Pointer to "struct tomoyo_policy_namespace".
+ * @domainname: The name of current domain.
+ * @program:    The name of requested program.
+ *
+ * Returns TOMOYO_TRANSITION_CONTROL_TRANSIT if executing @program causes
+ * domain transition across namespaces, TOMOYO_TRANSITION_CONTROL_INITIALIZE if
+ * executing @program reinitializes domain transition within that namespace,
+ * TOMOYO_TRANSITION_CONTROL_KEEP if executing @program stays at @domainname ,
+ * others otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+static enum tomoyo_transition_type tomoyo_transition_type
+(const struct tomoyo_policy_namespace *ns,
+ const struct tomoyo_path_info *domainname,
+ const struct tomoyo_path_info *program)
+{
+	const char *last_name = tomoyo_last_word(domainname->name);
+	enum tomoyo_transition_type type = TOMOYO_TRANSITION_CONTROL_NO_RESET;
+
+	while (type < TOMOYO_MAX_TRANSITION_TYPE) {
+		const struct list_head * const list =
+			&ns->policy_list[TOMOYO_ID_TRANSITION_CONTROL];
+
+		if (!tomoyo_scan_transition(list, domainname, program,
+					    last_name, type)) {
+			type++;
+			continue;
+		}
+		if (type != TOMOYO_TRANSITION_CONTROL_NO_RESET &&
+		    type != TOMOYO_TRANSITION_CONTROL_NO_INITIALIZE)
+			break;
+		/*
+		 * Do not check for reset_domain if no_reset_domain matched.
+		 * Do not check for initialize_domain if no_initialize_domain
+		 * matched.
+		 */
+		type++;
+		type++;
+	}
+	return type;
+}
+
+/**
+ * tomoyo_same_aggregator - Check for duplicated "struct tomoyo_aggregator" entry.
+ *
+ * @a: Pointer to "struct tomoyo_acl_head".
+ * @b: Pointer to "struct tomoyo_acl_head".
+ *
+ * Returns true if @a == @b, false otherwise.
+ */
+static bool tomoyo_same_aggregator(const struct tomoyo_acl_head *a,
+				   const struct tomoyo_acl_head *b)
+{
+	const struct tomoyo_aggregator *p1 = container_of(a, typeof(*p1),
+							  head);
+	const struct tomoyo_aggregator *p2 = container_of(b, typeof(*p2),
+							  head);
+
+	return p1->original_name == p2->original_name &&
+		p1->aggregated_name == p2->aggregated_name;
+}
+
+/**
+ * tomoyo_write_aggregator - Write "struct tomoyo_aggregator" list.
+ *
+ * @param: Pointer to "struct tomoyo_acl_param".
+ *
+ * Returns 0 on success, negative value otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+int tomoyo_write_aggregator(struct tomoyo_acl_param *param)
+{
+	struct tomoyo_aggregator e = { };
+	int error = param->is_delete ? -ENOENT : -ENOMEM;
+	const char *original_name = tomoyo_read_token(param);
+	const char *aggregated_name = tomoyo_read_token(param);
+
+	if (!tomoyo_correct_word(original_name) ||
+	    !tomoyo_correct_path(aggregated_name))
+		return -EINVAL;
+	e.original_name = tomoyo_get_name(original_name);
+	e.aggregated_name = tomoyo_get_name(aggregated_name);
+	if (!e.original_name || !e.aggregated_name ||
+	    e.aggregated_name->is_patterned) /* No patterns allowed. */
+		goto out;
+	param->list = &param->ns->policy_list[TOMOYO_ID_AGGREGATOR];
+	error = tomoyo_update_policy(&e.head, sizeof(e), param,
+				     tomoyo_same_aggregator);
+out:
+	tomoyo_put_name(e.original_name);
+	tomoyo_put_name(e.aggregated_name);
+	return error;
+}
+
+/**
+ * tomoyo_find_namespace - Find specified namespace.
+ *
+ * @name: Name of namespace to find.
+ * @len:  Length of @name.
+ *
+ * Returns pointer to "struct tomoyo_policy_namespace" if found,
+ * NULL otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+static struct tomoyo_policy_namespace *tomoyo_find_namespace
+(const char *name, const unsigned int len)
+{
+	struct tomoyo_policy_namespace *ns;
+
+	list_for_each_entry(ns, &tomoyo_namespace_list, namespace_list) {
+		if (strncmp(name, ns->name, len) ||
+		    (name[len] && name[len] != ' '))
+			continue;
+		return ns;
+	}
+	return NULL;
+}
+
+/**
+ * tomoyo_assign_namespace - Create a new namespace.
+ *
+ * @domainname: Name of namespace to create.
+ *
+ * Returns pointer to "struct tomoyo_policy_namespace" on success,
+ * NULL otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+struct tomoyo_policy_namespace *tomoyo_assign_namespace(const char *domainname)
+{
+	struct tomoyo_policy_namespace *ptr;
+	struct tomoyo_policy_namespace *entry;
+	const char *cp = domainname;
+	unsigned int len = 0;
+
+	while (*cp && *cp++ != ' ')
+		len++;
+	ptr = tomoyo_find_namespace(domainname, len);
+	if (ptr)
+		return ptr;
+	if (len >= TOMOYO_EXEC_TMPSIZE - 10 || !tomoyo_domain_def(domainname))
+		return NULL;
+	entry = kzalloc(sizeof(*entry) + len + 1, GFP_NOFS | __GFP_NOWARN);
+	if (mutex_lock_interruptible(&tomoyo_policy_lock))
+		goto out;
+	ptr = tomoyo_find_namespace(domainname, len);
+	if (!ptr && tomoyo_memory_ok(entry)) {
+		char *name = (char *) (entry + 1);
+
+		ptr = entry;
+		memmove(name, domainname, len);
+		name[len] = '\0';
+		entry->name = name;
+		tomoyo_init_policy_namespace(entry);
+		entry = NULL;
+	}
+	mutex_unlock(&tomoyo_policy_lock);
+out:
+	kfree(entry);
+	return ptr;
+}
+
+/**
+ * tomoyo_namespace_jump - Check for namespace jump.
+ *
+ * @domainname: Name of domain.
+ *
+ * Returns true if namespace differs, false otherwise.
+ */
+static bool tomoyo_namespace_jump(const char *domainname)
+{
+	const char *namespace = tomoyo_current_namespace()->name;
+	const int len = strlen(namespace);
+
+	return strncmp(domainname, namespace, len) ||
+		(domainname[len] && domainname[len] != ' ');
+}
+
+/**
+ * tomoyo_assign_domain - Create a domain or a namespace.
+ *
+ * @domainname: The name of domain.
+ * @transit:    True if transit to domain found or created.
+ *
+ * Returns pointer to "struct tomoyo_domain_info" on success, NULL otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+struct tomoyo_domain_info *tomoyo_assign_domain(const char *domainname,
+						const bool transit)
+{
+	struct tomoyo_domain_info e = { };
+	struct tomoyo_domain_info *entry = tomoyo_find_domain(domainname);
+	bool created = false;
+
+	if (entry) {
+		if (transit) {
+			/*
+			 * Since namespace is created at runtime, profiles may
+			 * not be created by the moment the process transits to
+			 * that domain. Do not perform domain transition if
+			 * profile for that domain is not yet created.
+			 */
+			if (tomoyo_policy_loaded &&
+			    !entry->ns->profile_ptr[entry->profile])
+				return NULL;
+		}
+		return entry;
+	}
+	/* Requested domain does not exist. */
+	/* Don't create requested domain if domainname is invalid. */
+	if (strlen(domainname) >= TOMOYO_EXEC_TMPSIZE - 10 ||
+	    !tomoyo_correct_domain(domainname))
+		return NULL;
+	/*
+	 * Since definition of profiles and acl_groups may differ across
+	 * namespaces, do not inherit "use_profile" and "use_group" settings
+	 * by automatically creating requested domain upon domain transition.
+	 */
+	if (transit && tomoyo_namespace_jump(domainname))
+		return NULL;
+	e.ns = tomoyo_assign_namespace(domainname);
+	if (!e.ns)
+		return NULL;
+	/*
+	 * "use_profile" and "use_group" settings for automatically created
+	 * domains are inherited from current domain. These are 0 for manually
+	 * created domains.
+	 */
+	if (transit) {
+		const struct tomoyo_domain_info *domain = tomoyo_domain();
+
+		e.profile = domain->profile;
+		memcpy(e.group, domain->group, sizeof(e.group));
+	}
+	e.domainname = tomoyo_get_name(domainname);
+	if (!e.domainname)
+		return NULL;
+	if (mutex_lock_interruptible(&tomoyo_policy_lock))
+		goto out;
+	entry = tomoyo_find_domain(domainname);
+	if (!entry) {
+		entry = tomoyo_commit_ok(&e, sizeof(e));
+		if (entry) {
+			INIT_LIST_HEAD(&entry->acl_info_list);
+			list_add_tail_rcu(&entry->list, &tomoyo_domain_list);
+			created = true;
+		}
+	}
+	mutex_unlock(&tomoyo_policy_lock);
+out:
+	tomoyo_put_name(e.domainname);
+	if (entry && transit) {
+		if (created) {
+			struct tomoyo_request_info r;
+			int i;
+
+			tomoyo_init_request_info(&r, entry,
+						 TOMOYO_MAC_FILE_EXECUTE);
+			r.granted = false;
+			tomoyo_write_log(&r, "use_profile %u\n",
+					 entry->profile);
+			for (i = 0; i < TOMOYO_MAX_ACL_GROUPS; i++)
+				if (test_bit(i, entry->group))
+					tomoyo_write_log(&r, "use_group %u\n",
+							 i);
+			tomoyo_update_stat(TOMOYO_STAT_POLICY_UPDATES);
+		}
+	}
+	return entry;
+}
+
+/**
+ * tomoyo_environ - Check permission for environment variable names.
+ *
+ * @ee: Pointer to "struct tomoyo_execve".
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+static int tomoyo_environ(struct tomoyo_execve *ee)
+{
+	struct tomoyo_request_info *r = &ee->r;
+	struct linux_binprm *bprm = ee->bprm;
+	/* env_page.data is allocated by tomoyo_dump_page(). */
+	struct tomoyo_page_dump env_page = { };
+	char *arg_ptr; /* Size is TOMOYO_EXEC_TMPSIZE bytes */
+	int arg_len = 0;
+	unsigned long pos = bprm->p;
+	int offset = pos % PAGE_SIZE;
+	int argv_count = bprm->argc;
+	int envp_count = bprm->envc;
+	int error = -ENOMEM;
+
+	ee->r.type = TOMOYO_MAC_ENVIRON;
+	ee->r.profile = r->domain->profile;
+	ee->r.mode = tomoyo_get_mode(r->domain->ns, ee->r.profile,
+				     TOMOYO_MAC_ENVIRON);
+	if (!r->mode || !envp_count)
+		return 0;
+	arg_ptr = kzalloc(TOMOYO_EXEC_TMPSIZE, GFP_NOFS);
+	if (!arg_ptr)
+		goto out;
+	while (error == -ENOMEM) {
+		if (!tomoyo_dump_page(bprm, pos, &env_page))
+			goto out;
+		pos += PAGE_SIZE - offset;
+		/* Read. */
+		while (argv_count && offset < PAGE_SIZE) {
+			if (!env_page.data[offset++])
+				argv_count--;
+		}
+		if (argv_count) {
+			offset = 0;
+			continue;
+		}
+		while (offset < PAGE_SIZE) {
+			const unsigned char c = env_page.data[offset++];
+
+			if (c && arg_len < TOMOYO_EXEC_TMPSIZE - 10) {
+				if (c == '=') {
+					arg_ptr[arg_len++] = '\0';
+				} else if (c == '\\') {
+					arg_ptr[arg_len++] = '\\';
+					arg_ptr[arg_len++] = '\\';
+				} else if (c > ' ' && c < 127) {
+					arg_ptr[arg_len++] = c;
+				} else {
+					arg_ptr[arg_len++] = '\\';
+					arg_ptr[arg_len++] = (c >> 6) + '0';
+					arg_ptr[arg_len++]
+						= ((c >> 3) & 7) + '0';
+					arg_ptr[arg_len++] = (c & 7) + '0';
+				}
+			} else {
+				arg_ptr[arg_len] = '\0';
+			}
+			if (c)
+				continue;
+			if (tomoyo_env_perm(r, arg_ptr)) {
+				error = -EPERM;
+				break;
+			}
+			if (!--envp_count) {
+				error = 0;
+				break;
+			}
+			arg_len = 0;
+		}
+		offset = 0;
+	}
+out:
+	if (r->mode != TOMOYO_CONFIG_ENFORCING)
+		error = 0;
+	kfree(env_page.data);
+	kfree(arg_ptr);
+	return error;
+}
+
+/**
+ * tomoyo_find_next_domain - Find a domain.
+ *
+ * @bprm: Pointer to "struct linux_binprm".
+ *
+ * Returns 0 on success, negative value otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+int tomoyo_find_next_domain(struct linux_binprm *bprm)
+{
+	struct tomoyo_domain_info *old_domain = tomoyo_domain();
+	struct tomoyo_domain_info *domain = NULL;
+	const char *original_name = bprm->filename;
+	int retval = -ENOMEM;
+	bool reject_on_transition_failure = false;
+	const struct tomoyo_path_info *candidate;
+	struct tomoyo_path_info exename;
+	struct tomoyo_execve *ee = kzalloc(sizeof(*ee), GFP_NOFS);
+
+	if (!ee)
+		return -ENOMEM;
+	ee->tmp = kzalloc(TOMOYO_EXEC_TMPSIZE, GFP_NOFS);
+	if (!ee->tmp) {
+		kfree(ee);
+		return -ENOMEM;
+	}
+	/* ee->dump->data is allocated by tomoyo_dump_page(). */
+	tomoyo_init_request_info(&ee->r, NULL, TOMOYO_MAC_FILE_EXECUTE);
+	ee->r.ee = ee;
+	ee->bprm = bprm;
+	ee->r.obj = &ee->obj;
+	ee->obj.path1 = bprm->file->f_path;
+	/* Get symlink's pathname of program. */
+	retval = -ENOENT;
+	exename.name = tomoyo_realpath_nofollow(original_name);
+	if (!exename.name)
+		goto out;
+	tomoyo_fill_path_info(&exename);
+retry:
+	/* Check 'aggregator' directive. */
+	{
+		struct tomoyo_aggregator *ptr;
+		struct list_head *list =
+			&old_domain->ns->policy_list[TOMOYO_ID_AGGREGATOR];
+
+		/* Check 'aggregator' directive. */
+		candidate = &exename;
+		list_for_each_entry_rcu(ptr, list, head.list,
+					srcu_read_lock_held(&tomoyo_ss)) {
+			if (ptr->head.is_deleted ||
+			    !tomoyo_path_matches_pattern(&exename,
+							 ptr->original_name))
+				continue;
+			candidate = ptr->aggregated_name;
+			break;
+		}
+	}
+
+	/* Check execute permission. */
+	retval = tomoyo_execute_permission(&ee->r, candidate);
+	if (retval == TOMOYO_RETRY_REQUEST)
+		goto retry;
+	if (retval < 0)
+		goto out;
+	/*
+	 * To be able to specify domainnames with wildcards, use the
+	 * pathname specified in the policy (which may contain
+	 * wildcard) rather than the pathname passed to execve()
+	 * (which never contains wildcard).
+	 */
+	if (ee->r.param.path.matched_path)
+		candidate = ee->r.param.path.matched_path;
+
+	/*
+	 * Check for domain transition preference if "file execute" matched.
+	 * If preference is given, make execve() fail if domain transition
+	 * has failed, for domain transition preference should be used with
+	 * destination domain defined.
+	 */
+	if (ee->transition) {
+		const char *domainname = ee->transition->name;
+
+		reject_on_transition_failure = true;
+		if (!strcmp(domainname, "keep"))
+			goto force_keep_domain;
+		if (!strcmp(domainname, "child"))
+			goto force_child_domain;
+		if (!strcmp(domainname, "reset"))
+			goto force_reset_domain;
+		if (!strcmp(domainname, "initialize"))
+			goto force_initialize_domain;
+		if (!strcmp(domainname, "parent")) {
+			char *cp;
+
+			strncpy(ee->tmp, old_domain->domainname->name,
+				TOMOYO_EXEC_TMPSIZE - 1);
+			cp = strrchr(ee->tmp, ' ');
+			if (cp)
+				*cp = '\0';
+		} else if (*domainname == '<')
+			strncpy(ee->tmp, domainname, TOMOYO_EXEC_TMPSIZE - 1);
+		else
+			snprintf(ee->tmp, TOMOYO_EXEC_TMPSIZE - 1, "%s %s",
+				 old_domain->domainname->name, domainname);
+		goto force_jump_domain;
+	}
+	/*
+	 * No domain transition preference specified.
+	 * Calculate domain to transit to.
+	 */
+	switch (tomoyo_transition_type(old_domain->ns, old_domain->domainname,
+				       candidate)) {
+	case TOMOYO_TRANSITION_CONTROL_RESET:
+force_reset_domain:
+		/* Transit to the root of specified namespace. */
+		snprintf(ee->tmp, TOMOYO_EXEC_TMPSIZE - 1, "<%s>",
+			 candidate->name);
+		/*
+		 * Make execve() fail if domain transition across namespaces
+		 * has failed.
+		 */
+		reject_on_transition_failure = true;
+		break;
+	case TOMOYO_TRANSITION_CONTROL_INITIALIZE:
+force_initialize_domain:
+		/* Transit to the child of current namespace's root. */
+		snprintf(ee->tmp, TOMOYO_EXEC_TMPSIZE - 1, "%s %s",
+			 old_domain->ns->name, candidate->name);
+		break;
+	case TOMOYO_TRANSITION_CONTROL_KEEP:
+force_keep_domain:
+		/* Keep current domain. */
+		domain = old_domain;
+		break;
+	default:
+		if (old_domain == &tomoyo_kernel_domain &&
+		    !tomoyo_policy_loaded) {
+			/*
+			 * Needn't to transit from kernel domain before
+			 * starting /sbin/init. But transit from kernel domain
+			 * if executing initializers because they might start
+			 * before /sbin/init.
+			 */
+			domain = old_domain;
+			break;
+		}
+force_child_domain:
+		/* Normal domain transition. */
+		snprintf(ee->tmp, TOMOYO_EXEC_TMPSIZE - 1, "%s %s",
+			 old_domain->domainname->name, candidate->name);
+		break;
+	}
+force_jump_domain:
+	if (!domain)
+		domain = tomoyo_assign_domain(ee->tmp, true);
+	if (domain)
+		retval = 0;
+	else if (reject_on_transition_failure) {
+		pr_warn("ERROR: Domain '%s' not ready.\n", ee->tmp);
+		retval = -ENOMEM;
+	} else if (ee->r.mode == TOMOYO_CONFIG_ENFORCING)
+		retval = -ENOMEM;
+	else {
+		retval = 0;
+		if (!old_domain->flags[TOMOYO_DIF_TRANSITION_FAILED]) {
+			old_domain->flags[TOMOYO_DIF_TRANSITION_FAILED] = true;
+			ee->r.granted = false;
+			tomoyo_write_log(&ee->r, "%s", tomoyo_dif
+					 [TOMOYO_DIF_TRANSITION_FAILED]);
+			pr_warn("ERROR: Domain '%s' not defined.\n", ee->tmp);
+		}
+	}
+ out:
+	if (!domain)
+		domain = old_domain;
+	/* Update reference count on "struct tomoyo_domain_info". */
+	{
+		struct tomoyo_task *s = tomoyo_task(current);
+
+		s->old_domain_info = s->domain_info;
+		s->domain_info = domain;
+		atomic_inc(&domain->users);
+	}
+	kfree(exename.name);
+	if (!retval) {
+		ee->r.domain = domain;
+		retval = tomoyo_environ(ee);
+	}
+	kfree(ee->tmp);
+	kfree(ee->dump.data);
+	kfree(ee);
+	return retval;
+}
+
+/**
+ * tomoyo_dump_page - Dump a page to buffer.
+ *
+ * @bprm: Pointer to "struct linux_binprm".
+ * @pos:  Location to dump.
+ * @dump: Pointer to "struct tomoyo_page_dump".
+ *
+ * Returns true on success, false otherwise.
+ */
+bool tomoyo_dump_page(struct linux_binprm *bprm, unsigned long pos,
+		      struct tomoyo_page_dump *dump)
+{
+	struct page *page;
+#ifdef CONFIG_MMU
+	int ret;
+#endif
+
+	/* dump->data is released by tomoyo_find_next_domain(). */
+	if (!dump->data) {
+		dump->data = kzalloc(PAGE_SIZE, GFP_NOFS);
+		if (!dump->data)
+			return false;
+	}
+	/* Same with get_arg_page(bprm, pos, 0) in fs/exec.c */
+#ifdef CONFIG_MMU
+	/*
+	 * This is called at execve() time in order to dig around
+	 * in the argv/environment of the new proceess
+	 * (represented by bprm).
+	 */
+	mmap_read_lock(bprm->mm);
+	ret = get_user_pages_remote(bprm->mm, pos, 1,
+				    FOLL_FORCE, &page, NULL, NULL);
+	mmap_read_unlock(bprm->mm);
+	if (ret <= 0)
+		return false;
+#else
+	page = bprm->page[pos / PAGE_SIZE];
+#endif
+	if (page != dump->page) {
+		const unsigned int offset = pos % PAGE_SIZE;
+		/*
+		 * Maybe kmap()/kunmap() should be used here.
+		 * But remove_arg_zero() uses kmap_atomic()/kunmap_atomic().
+		 * So do I.
+		 */
+		char *kaddr = kmap_atomic(page);
+
+		dump->page = page;
+		memcpy(dump->data + offset, kaddr + offset,
+		       PAGE_SIZE - offset);
+		kunmap_atomic(kaddr);
+	}
+	/* Same with put_arg_page(page) in fs/exec.c */
+#ifdef CONFIG_MMU
+	put_page(page);
+#endif
+	return true;
+}