Domain transition handler.

This file controls domain creation/deletion/transition.

Every process belongs to a domain in TOMOYO Linux.
Domain transition occurs when execve(2) is called
and the domain is expressed as 'process invocation history',
such as '<kernel> /sbin/init /etc/init.d/rc'.
Domain information is stored in current->cred->security field.

Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 878 insertions, 0 deletions

diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
new file mode 100644
index 000000000000..92af8f50e0fa
--- /dev/null
+++ b/security/tomoyo/domain.c
@@ -0,0 +1,878 @@
+/*
+ * security/tomoyo/domain.c
+ *
+ * Implementation of the Domain-Based Mandatory Access Control.
+ *
+ * Copyright (C) 2005-2009  NTT DATA CORPORATION
+ *
+ * Version: 2.2.0-pre   2009/02/01
+ *
+ */
+
+#include "common.h"
+#include "tomoyo.h"
+#include "realpath.h"
+#include <linux/binfmts.h>
+
+/* Variables definitions.*/
+
+/* The initial domain. */
+struct tomoyo_domain_info tomoyo_kernel_domain;
+
+/* The list for "struct tomoyo_domain_info". */
+LIST_HEAD(tomoyo_domain_list);
+DECLARE_RWSEM(tomoyo_domain_list_lock);
+
+/* Structure for "initialize_domain" and "no_initialize_domain" keyword. */
+struct tomoyo_domain_initializer_entry {
+        struct list_head list;
+        const struct tomoyo_path_info *domainname;    /* This may be NULL */
+        const struct tomoyo_path_info *program;
+        bool is_deleted;
+        bool is_not;       /* True if this entry is "no_initialize_domain".  */
+        /* True if the domainname is tomoyo_get_last_name(). */
+        bool is_last_name;
+};
+
+/* Structure for "keep_domain" and "no_keep_domain" keyword. */
+struct tomoyo_domain_keeper_entry {
+        struct list_head list;
+        const struct tomoyo_path_info *domainname;
+        const struct tomoyo_path_info *program;       /* This may be NULL */
+        bool is_deleted;
+        bool is_not;       /* True if this entry is "no_keep_domain".        */
+        /* True if the domainname is tomoyo_get_last_name(). */
+        bool is_last_name;
+};
+
+/* Structure for "alias" keyword. */
+struct tomoyo_alias_entry {
+        struct list_head list;
+        const struct tomoyo_path_info *original_name;
+        const struct tomoyo_path_info *aliased_name;
+        bool is_deleted;
+};
+
+/**
+ * tomoyo_set_domain_flag - Set or clear domain's attribute flags.
+ *
+ * @domain:    Pointer to "struct tomoyo_domain_info".
+ * @is_delete: True if it is a delete request.
+ * @flags:     Flags to set or clear.
+ *
+ * Returns nothing.
+ */
+void tomoyo_set_domain_flag(struct tomoyo_domain_info *domain,
+                            const bool is_delete, const u8 flags)
+{
+        /* We need to serialize because this is bitfield operation. */
+        static DEFINE_SPINLOCK(lock);
+        /***** CRITICAL SECTION START *****/
+        spin_lock(&lock);
+        if (!is_delete)
+                domain->flags |= flags;
+        else
+                domain->flags &= ~flags;
+        spin_unlock(&lock);
+        /***** CRITICAL SECTION END *****/
+}
+
+/**
+ * tomoyo_get_last_name - Get last component of a domainname.
+ *
+ * @domain: Pointer to "struct tomoyo_domain_info".
+ *
+ * Returns the last component of the domainname.
+ */
+const char *tomoyo_get_last_name(const struct tomoyo_domain_info *domain)
+{
+        const char *cp0 = domain->domainname->name;
+        const char *cp1 = strrchr(cp0, ' ');
+
+        if (cp1)
+                return cp1 + 1;
+        return cp0;
+}
+
+/* The list for "struct tomoyo_domain_initializer_entry". */
+static LIST_HEAD(tomoyo_domain_initializer_list);
+static DECLARE_RWSEM(tomoyo_domain_initializer_list_lock);
+
+/**
+ * tomoyo_update_domain_initializer_entry - Update "struct tomoyo_domain_initializer_entry" list.
+ *
+ * @domainname: The name of domain. May be NULL.
+ * @program:    The name of program.
+ * @is_not:     True if it is "no_initialize_domain" entry.
+ * @is_delete:  True if it is a delete request.
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+static int tomoyo_update_domain_initializer_entry(const char *domainname,
+                                                  const char *program,
+                                                  const bool is_not,
+                                                  const bool is_delete)
+{
+        struct tomoyo_domain_initializer_entry *new_entry;
+        struct tomoyo_domain_initializer_entry *ptr;
+        const struct tomoyo_path_info *saved_program;
+        const struct tomoyo_path_info *saved_domainname = NULL;
+        int error = -ENOMEM;
+        bool is_last_name = false;
+
+        if (!tomoyo_is_correct_path(program, 1, -1, -1, __func__))
+                return -EINVAL; /* No patterns allowed. */
+        if (domainname) {
+                if (!tomoyo_is_domain_def(domainname) &&
+                    tomoyo_is_correct_path(domainname, 1, -1, -1, __func__))
+                        is_last_name = true;
+                else if (!tomoyo_is_correct_domain(domainname, __func__))
+                        return -EINVAL;
+                saved_domainname = tomoyo_save_name(domainname);
+                if (!saved_domainname)
+                        return -ENOMEM;
+        }
+        saved_program = tomoyo_save_name(program);
+        if (!saved_program)
+                return -ENOMEM;
+        /***** EXCLUSIVE SECTION START *****/
+        down_write(&tomoyo_domain_initializer_list_lock);
+        list_for_each_entry(ptr, &tomoyo_domain_initializer_list, list) {
+                if (ptr->is_not != is_not ||
+                    ptr->domainname != saved_domainname ||
+                    ptr->program != saved_program)
+                        continue;
+                ptr->is_deleted = is_delete;
+                error = 0;
+                goto out;
+        }
+        if (is_delete) {
+                error = -ENOENT;
+                goto out;
+        }
+        new_entry = tomoyo_alloc_element(sizeof(*new_entry));
+        if (!new_entry)
+                goto out;
+        new_entry->domainname = saved_domainname;
+        new_entry->program = saved_program;
+        new_entry->is_not = is_not;
+        new_entry->is_last_name = is_last_name;
+        list_add_tail(&new_entry->list, &tomoyo_domain_initializer_list);
+        error = 0;
+ out:
+        up_write(&tomoyo_domain_initializer_list_lock);
+        /***** EXCLUSIVE SECTION END *****/
+        return error;
+}
+
+/**
+ * tomoyo_read_domain_initializer_policy - Read "struct tomoyo_domain_initializer_entry" list.
+ *
+ * @head: Pointer to "struct tomoyo_io_buffer".
+ *
+ * Returns true on success, false otherwise.
+ */
+bool tomoyo_read_domain_initializer_policy(struct tomoyo_io_buffer *head)
+{
+        struct list_head *pos;
+        bool done = true;
+
+        down_read(&tomoyo_domain_initializer_list_lock);
+        list_for_each_cookie(pos, head->read_var2,
+                             &tomoyo_domain_initializer_list) {
+                const char *no;
+                const char *from = "";
+                const char *domain = "";
+                struct tomoyo_domain_initializer_entry *ptr;
+                ptr = list_entry(pos, struct tomoyo_domain_initializer_entry,
+                                  list);
+                if (ptr->is_deleted)
+                        continue;
+                no = ptr->is_not ? "no_" : "";
+                if (ptr->domainname) {
+                        from = " from ";
+                        domain = ptr->domainname->name;
+                }
+                if (!tomoyo_io_printf(head,
+                                      "%s" TOMOYO_KEYWORD_INITIALIZE_DOMAIN
+                                      "%s%s%s\n", no, ptr->program->name, from,
+                                      domain)) {
+                        done = false;
+                        break;
+                }
+        }
+        up_read(&tomoyo_domain_initializer_list_lock);
+        return done;
+}
+
+/**
+ * tomoyo_write_domain_initializer_policy - Write "struct tomoyo_domain_initializer_entry" list.
+ *
+ * @data:      String to parse.
+ * @is_not:    True if it is "no_initialize_domain" entry.
+ * @is_delete: True if it is a delete request.
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+int tomoyo_write_domain_initializer_policy(char *data, const bool is_not,
+                                           const bool is_delete)
+{
+        char *cp = strstr(data, " from ");
+
+        if (cp) {
+                *cp = '\0';
+                return tomoyo_update_domain_initializer_entry(cp + 6, data,
+                                                              is_not,
+                                                              is_delete);
+        }
+        return tomoyo_update_domain_initializer_entry(NULL, data, is_not,
+                                                      is_delete);
+}
+
+/**
+ * tomoyo_is_domain_initializer - Check whether the given program causes domainname reinitialization.
+ *
+ * @domainname: The name of domain.
+ * @program:    The name of program.
+ * @last_name:  The last component of @domainname.
+ *
+ * Returns true if executing @program reinitializes domain transition,
+ * false otherwise.
+ */
+static bool tomoyo_is_domain_initializer(const struct tomoyo_path_info *
+                                         domainname,
+                                         const struct tomoyo_path_info *program,
+                                         const struct tomoyo_path_info *
+                                         last_name)
+{
+        struct tomoyo_domain_initializer_entry *ptr;
+        bool flag = false;
+
+        down_read(&tomoyo_domain_initializer_list_lock);
+        list_for_each_entry(ptr,  &tomoyo_domain_initializer_list, list) {
+                if (ptr->is_deleted)
+                        continue;
+                if (ptr->domainname) {
+                        if (!ptr->is_last_name) {
+                                if (ptr->domainname != domainname)
+                                        continue;
+                        } else {
+                                if (tomoyo_pathcmp(ptr->domainname, last_name))
+                                        continue;
+                        }
+                }
+                if (tomoyo_pathcmp(ptr->program, program))
+                        continue;
+                if (ptr->is_not) {
+                        flag = false;
+                        break;
+                }
+                flag = true;
+        }
+        up_read(&tomoyo_domain_initializer_list_lock);
+        return flag;
+}
+
+/* The list for "struct tomoyo_domain_keeper_entry". */
+static LIST_HEAD(tomoyo_domain_keeper_list);
+static DECLARE_RWSEM(tomoyo_domain_keeper_list_lock);
+
+/**
+ * tomoyo_update_domain_keeper_entry - Update "struct tomoyo_domain_keeper_entry" list.
+ *
+ * @domainname: The name of domain.
+ * @program:    The name of program. May be NULL.
+ * @is_not:     True if it is "no_keep_domain" entry.
+ * @is_delete:  True if it is a delete request.
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+static int tomoyo_update_domain_keeper_entry(const char *domainname,
+                                             const char *program,
+                                             const bool is_not,
+                                             const bool is_delete)
+{
+        struct tomoyo_domain_keeper_entry *new_entry;
+        struct tomoyo_domain_keeper_entry *ptr;
+        const struct tomoyo_path_info *saved_domainname;
+        const struct tomoyo_path_info *saved_program = NULL;
+        static DEFINE_MUTEX(lock);
+        int error = -ENOMEM;
+        bool is_last_name = false;
+
+        if (!tomoyo_is_domain_def(domainname) &&
+            tomoyo_is_correct_path(domainname, 1, -1, -1, __func__))
+                is_last_name = true;
+        else if (!tomoyo_is_correct_domain(domainname, __func__))
+                return -EINVAL;
+        if (program) {
+                if (!tomoyo_is_correct_path(program, 1, -1, -1, __func__))
+                        return -EINVAL;
+                saved_program = tomoyo_save_name(program);
+                if (!saved_program)
+                        return -ENOMEM;
+        }
+        saved_domainname = tomoyo_save_name(domainname);
+        if (!saved_domainname)
+                return -ENOMEM;
+        /***** EXCLUSIVE SECTION START *****/
+        down_write(&tomoyo_domain_keeper_list_lock);
+        list_for_each_entry(ptr, &tomoyo_domain_keeper_list, list) {
+                if (ptr->is_not != is_not ||
+                    ptr->domainname != saved_domainname ||
+                    ptr->program != saved_program)
+                        continue;
+                ptr->is_deleted = is_delete;
+                error = 0;
+                goto out;
+        }
+        if (is_delete) {
+                error = -ENOENT;
+                goto out;
+        }
+        new_entry = tomoyo_alloc_element(sizeof(*new_entry));
+        if (!new_entry)
+                goto out;
+        new_entry->domainname = saved_domainname;
+        new_entry->program = saved_program;
+        new_entry->is_not = is_not;
+        new_entry->is_last_name = is_last_name;
+        list_add_tail(&new_entry->list, &tomoyo_domain_keeper_list);
+        error = 0;
+ out:
+        up_write(&tomoyo_domain_keeper_list_lock);
+        /***** EXCLUSIVE SECTION END *****/
+        return error;
+}
+
+/**
+ * tomoyo_write_domain_keeper_policy - Write "struct tomoyo_domain_keeper_entry" list.
+ *
+ * @data:      String to parse.
+ * @is_not:    True if it is "no_keep_domain" entry.
+ * @is_delete: True if it is a delete request.
+ *
+ */
+int tomoyo_write_domain_keeper_policy(char *data, const bool is_not,
+                                      const bool is_delete)
+{
+        char *cp = strstr(data, " from ");
+
+        if (cp) {
+                *cp = '\0';
+                return tomoyo_update_domain_keeper_entry(cp + 6, data, is_not,
+                                                         is_delete);
+        }
+        return tomoyo_update_domain_keeper_entry(data, NULL, is_not, is_delete);
+}
+
+/**
+ * tomoyo_read_domain_keeper_policy - Read "struct tomoyo_domain_keeper_entry" list.
+ *
+ * @head: Pointer to "struct tomoyo_io_buffer".
+ *
+ * Returns true on success, false otherwise.
+ */
+bool tomoyo_read_domain_keeper_policy(struct tomoyo_io_buffer *head)
+{
+        struct list_head *pos;
+        bool done = false;
+
+        down_read(&tomoyo_domain_keeper_list_lock);
+        list_for_each_cookie(pos, head->read_var2,
+                             &tomoyo_domain_keeper_list) {
+                struct tomoyo_domain_keeper_entry *ptr;
+                const char *no;
+                const char *from = "";
+                const char *program = "";
+
+                ptr = list_entry(pos, struct tomoyo_domain_keeper_entry, list);
+                if (ptr->is_deleted)
+                        continue;
+                no = ptr->is_not ? "no_" : "";
+                if (ptr->program) {
+                        from = " from ";
+                        program = ptr->program->name;
+                }
+                if (!tomoyo_io_printf(head,
+                                      "%s" TOMOYO_KEYWORD_KEEP_DOMAIN
+                                      "%s%s%s\n", no, program, from,
+                                      ptr->domainname->name)) {
+                        done = false;
+                        break;
+                }
+        }
+        up_read(&tomoyo_domain_keeper_list_lock);
+        return done;
+}
+
+/**
+ * tomoyo_is_domain_keeper - Check whether the given program causes domain transition suppression.
+ *
+ * @domainname: The name of domain.
+ * @program:    The name of program.
+ * @last_name:  The last component of @domainname.
+ *
+ * Returns true if executing @program supresses domain transition,
+ * false otherwise.
+ */
+static bool tomoyo_is_domain_keeper(const struct tomoyo_path_info *domainname,
+                                    const struct tomoyo_path_info *program,
+                                    const struct tomoyo_path_info *last_name)
+{
+        struct tomoyo_domain_keeper_entry *ptr;
+        bool flag = false;
+
+        down_read(&tomoyo_domain_keeper_list_lock);
+        list_for_each_entry(ptr, &tomoyo_domain_keeper_list, list) {
+                if (ptr->is_deleted)
+                        continue;
+                if (!ptr->is_last_name) {
+                        if (ptr->domainname != domainname)
+                                continue;
+                } else {
+                        if (tomoyo_pathcmp(ptr->domainname, last_name))
+                                continue;
+                }
+                if (ptr->program && tomoyo_pathcmp(ptr->program, program))
+                        continue;
+                if (ptr->is_not) {
+                        flag = false;
+                        break;
+                }
+                flag = true;
+        }
+        up_read(&tomoyo_domain_keeper_list_lock);
+        return flag;
+}
+
+/* The list for "struct tomoyo_alias_entry". */
+static LIST_HEAD(tomoyo_alias_list);
+static DECLARE_RWSEM(tomoyo_alias_list_lock);
+
+/**
+ * tomoyo_update_alias_entry - Update "struct tomoyo_alias_entry" list.
+ *
+ * @original_name: The original program's real name.
+ * @aliased_name:  The symbolic program's symbolic link's name.
+ * @is_delete:     True if it is a delete request.
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+static int tomoyo_update_alias_entry(const char *original_name,
+                                     const char *aliased_name,
+                                     const bool is_delete)
+{
+        struct tomoyo_alias_entry *new_entry;
+        struct tomoyo_alias_entry *ptr;
+        const struct tomoyo_path_info *saved_original_name;
+        const struct tomoyo_path_info *saved_aliased_name;
+        int error = -ENOMEM;
+
+        if (!tomoyo_is_correct_path(original_name, 1, -1, -1, __func__) ||
+            !tomoyo_is_correct_path(aliased_name, 1, -1, -1, __func__))
+                return -EINVAL; /* No patterns allowed. */
+        saved_original_name = tomoyo_save_name(original_name);
+        saved_aliased_name = tomoyo_save_name(aliased_name);
+        if (!saved_original_name || !saved_aliased_name)
+                return -ENOMEM;
+        /***** EXCLUSIVE SECTION START *****/
+        down_write(&tomoyo_alias_list_lock);
+        list_for_each_entry(ptr, &tomoyo_alias_list, list) {
+                if (ptr->original_name != saved_original_name ||
+                    ptr->aliased_name != saved_aliased_name)
+                        continue;
+                ptr->is_deleted = is_delete;
+                error = 0;
+                goto out;
+        }
+        if (is_delete) {
+                error = -ENOENT;
+                goto out;
+        }
+        new_entry = tomoyo_alloc_element(sizeof(*new_entry));
+        if (!new_entry)
+                goto out;
+        new_entry->original_name = saved_original_name;
+        new_entry->aliased_name = saved_aliased_name;
+        list_add_tail(&new_entry->list, &tomoyo_alias_list);
+        error = 0;
+ out:
+        up_write(&tomoyo_alias_list_lock);
+        /***** EXCLUSIVE SECTION END *****/
+        return error;
+}
+
+/**
+ * tomoyo_read_alias_policy - Read "struct tomoyo_alias_entry" list.
+ *
+ * @head: Pointer to "struct tomoyo_io_buffer".
+ *
+ * Returns true on success, false otherwise.
+ */
+bool tomoyo_read_alias_policy(struct tomoyo_io_buffer *head)
+{
+        struct list_head *pos;
+        bool done = true;
+
+        down_read(&tomoyo_alias_list_lock);
+        list_for_each_cookie(pos, head->read_var2, &tomoyo_alias_list) {
+                struct tomoyo_alias_entry *ptr;
+
+                ptr = list_entry(pos, struct tomoyo_alias_entry, list);
+                if (ptr->is_deleted)
+                        continue;
+                if (!tomoyo_io_printf(head, TOMOYO_KEYWORD_ALIAS "%s %s\n",
+                                      ptr->original_name->name,
+                                      ptr->aliased_name->name)) {
+                        done = false;
+                        break;
+                }
+        }
+        up_read(&tomoyo_alias_list_lock);
+        return done;
+}
+
+/**
+ * tomoyo_write_alias_policy - Write "struct tomoyo_alias_entry" list.
+ *
+ * @data:      String to parse.
+ * @is_delete: True if it is a delete request.
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+int tomoyo_write_alias_policy(char *data, const bool is_delete)
+{
+        char *cp = strchr(data, ' ');
+
+        if (!cp)
+                return -EINVAL;
+        *cp++ = '\0';
+        return tomoyo_update_alias_entry(data, cp, is_delete);
+}
+
+/* Domain create/delete/undelete handler. */
+
+/* #define TOMOYO_DEBUG_DOMAIN_UNDELETE */
+
+/**
+ * tomoyo_delete_domain - Delete a domain.
+ *
+ * @domainname: The name of domain.
+ *
+ * Returns 0.
+ */
+int tomoyo_delete_domain(char *domainname)
+{
+        struct tomoyo_domain_info *domain;
+        struct tomoyo_path_info name;
+
+        name.name = domainname;
+        tomoyo_fill_path_info(&name);
+        /***** EXCLUSIVE SECTION START *****/
+        down_write(&tomoyo_domain_list_lock);
+#ifdef TOMOYO_DEBUG_DOMAIN_UNDELETE
+        printk(KERN_DEBUG "tomoyo_delete_domain %s\n", domainname);
+        list_for_each_entry(domain, &tomoyo_domain_list, list) {
+                if (tomoyo_pathcmp(domain->domainname, &name))
+                        continue;
+                printk(KERN_DEBUG "List: %p %u\n", domain, domain->is_deleted);
+        }
+#endif
+        /* Is there an active domain? */
+        list_for_each_entry(domain, &tomoyo_domain_list, list) {
+                struct tomoyo_domain_info *domain2;
+                /* Never delete tomoyo_kernel_domain */
+                if (domain == &tomoyo_kernel_domain)
+                        continue;
+                if (domain->is_deleted ||
+                    tomoyo_pathcmp(domain->domainname, &name))
+                        continue;
+                /* Mark already deleted domains as non undeletable. */
+                list_for_each_entry(domain2, &tomoyo_domain_list, list) {
+                        if (!domain2->is_deleted ||
+                            tomoyo_pathcmp(domain2->domainname, &name))
+                                continue;
+#ifdef TOMOYO_DEBUG_DOMAIN_UNDELETE
+                        if (domain2->is_deleted != 255)
+                                printk(KERN_DEBUG
+                                       "Marked %p as non undeletable\n",
+                                       domain2);
+#endif
+                        domain2->is_deleted = 255;
+                }
+                /* Delete and mark active domain as undeletable. */
+                domain->is_deleted = 1;
+#ifdef TOMOYO_DEBUG_DOMAIN_UNDELETE
+                printk(KERN_DEBUG "Marked %p as undeletable\n", domain);
+#endif
+                break;
+        }
+        up_write(&tomoyo_domain_list_lock);
+        /***** EXCLUSIVE SECTION END *****/
+        return 0;
+}
+
+/**
+ * tomoyo_undelete_domain - Undelete a domain.
+ *
+ * @domainname: The name of domain.
+ *
+ * Returns pointer to "struct tomoyo_domain_info" on success, NULL otherwise.
+ */
+struct tomoyo_domain_info *tomoyo_undelete_domain(const char *domainname)
+{
+        struct tomoyo_domain_info *domain;
+        struct tomoyo_domain_info *candidate_domain = NULL;
+        struct tomoyo_path_info name;
+
+        name.name = domainname;
+        tomoyo_fill_path_info(&name);
+        /***** EXCLUSIVE SECTION START *****/
+        down_write(&tomoyo_domain_list_lock);
+#ifdef TOMOYO_DEBUG_DOMAIN_UNDELETE
+        printk(KERN_DEBUG "tomoyo_undelete_domain %s\n", domainname);
+        list_for_each_entry(domain, &tomoyo_domain_list, list) {
+                if (tomoyo_pathcmp(domain->domainname, &name))
+                        continue;
+                printk(KERN_DEBUG "List: %p %u\n", domain, domain->is_deleted);
+        }
+#endif
+        list_for_each_entry(domain, &tomoyo_domain_list, list) {
+                if (tomoyo_pathcmp(&name, domain->domainname))
+                        continue;
+                if (!domain->is_deleted) {
+                        /* This domain is active. I can't undelete. */
+                        candidate_domain = NULL;
+#ifdef TOMOYO_DEBUG_DOMAIN_UNDELETE
+                        printk(KERN_DEBUG "%p is active. I can't undelete.\n",
+                               domain);
+#endif
+                        break;
+                }
+                /* Is this domain undeletable? */
+                if (domain->is_deleted == 1)
+                        candidate_domain = domain;
+        }
+        if (candidate_domain) {
+                candidate_domain->is_deleted = 0;
+#ifdef TOMOYO_DEBUG_DOMAIN_UNDELETE
+                printk(KERN_DEBUG "%p was undeleted.\n", candidate_domain);
+#endif
+        }
+        up_write(&tomoyo_domain_list_lock);
+        /***** EXCLUSIVE SECTION END *****/
+        return candidate_domain;
+}
+
+/**
+ * tomoyo_find_or_assign_new_domain - Create a domain.
+ *
+ * @domainname: The name of domain.
+ * @profile:    Profile number to assign if the domain was newly created.
+ *
+ * Returns pointer to "struct tomoyo_domain_info" on success, NULL otherwise.
+ */
+struct tomoyo_domain_info *tomoyo_find_or_assign_new_domain(const char *
+                                                            domainname,
+                                                            const u8 profile)
+{
+        struct tomoyo_domain_info *domain = NULL;
+        const struct tomoyo_path_info *saved_domainname;
+
+        /***** EXCLUSIVE SECTION START *****/
+        down_write(&tomoyo_domain_list_lock);
+        domain = tomoyo_find_domain(domainname);
+        if (domain)
+                goto out;
+        if (!tomoyo_is_correct_domain(domainname, __func__))
+                goto out;
+        saved_domainname = tomoyo_save_name(domainname);
+        if (!saved_domainname)
+                goto out;
+        /* Can I reuse memory of deleted domain? */
+        list_for_each_entry(domain, &tomoyo_domain_list, list) {
+                struct task_struct *p;
+                struct tomoyo_acl_info *ptr;
+                bool flag;
+                if (!domain->is_deleted ||
+                    domain->domainname != saved_domainname)
+                        continue;
+                flag = false;
+                /***** CRITICAL SECTION START *****/
+                read_lock(&tasklist_lock);
+                for_each_process(p) {
+                        if (tomoyo_real_domain(p) != domain)
+                                continue;
+                        flag = true;
+                        break;
+                }
+                read_unlock(&tasklist_lock);
+                /***** CRITICAL SECTION END *****/
+                if (flag)
+                        continue;
+#ifdef TOMOYO_DEBUG_DOMAIN_UNDELETE
+                printk(KERN_DEBUG "Reusing %p %s\n", domain,
+                       domain->domainname->name);
+#endif
+                list_for_each_entry(ptr, &domain->acl_info_list, list) {
+                        ptr->type |= TOMOYO_ACL_DELETED;
+                }
+                tomoyo_set_domain_flag(domain, true, domain->flags);
+                domain->profile = profile;
+                domain->quota_warned = false;
+                mb(); /* Avoid out-of-order execution. */
+                domain->is_deleted = 0;
+                goto out;
+        }
+        /* No memory reusable. Create using new memory. */
+        domain = tomoyo_alloc_element(sizeof(*domain));
+        if (domain) {
+                INIT_LIST_HEAD(&domain->acl_info_list);
+                domain->domainname = saved_domainname;
+                domain->profile = profile;
+                list_add_tail(&domain->list, &tomoyo_domain_list);
+        }
+ out:
+        up_write(&tomoyo_domain_list_lock);
+        /***** EXCLUSIVE SECTION END *****/
+        return domain;
+}
+
+/**
+ * tomoyo_find_next_domain - Find a domain.
+ *
+ * @bprm:           Pointer to "struct linux_binprm".
+ * @next_domain:    Pointer to pointer to "struct tomoyo_domain_info".
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+int tomoyo_find_next_domain(struct linux_binprm *bprm,
+                            struct tomoyo_domain_info **next_domain)
+{
+        /*
+         * This function assumes that the size of buffer returned by
+         * tomoyo_realpath() = TOMOYO_MAX_PATHNAME_LEN.
+         */
+        struct tomoyo_page_buffer *tmp = tomoyo_alloc(sizeof(*tmp));
+        struct tomoyo_domain_info *old_domain = tomoyo_domain();
+        struct tomoyo_domain_info *domain = NULL;
+        const char *old_domain_name = old_domain->domainname->name;
+        const char *original_name = bprm->filename;
+        char *new_domain_name = NULL;
+        char *real_program_name = NULL;
+        char *symlink_program_name = NULL;
+        const u8 mode = tomoyo_check_flags(old_domain, TOMOYO_MAC_FOR_FILE);
+        const bool is_enforce = (mode == 3);
+        int retval = -ENOMEM;
+        struct tomoyo_path_info r; /* real name */
+        struct tomoyo_path_info s; /* symlink name */
+        struct tomoyo_path_info l; /* last name */
+        static bool initialized;
+
+        if (!tmp)
+                goto out;
+
+        if (!initialized) {
+                /*
+                 * Built-in initializers. This is needed because policies are
+                 * not loaded until starting /sbin/init.
+                 */
+                tomoyo_update_domain_initializer_entry(NULL, "/sbin/hotplug",
+                                                       false, false);
+                tomoyo_update_domain_initializer_entry(NULL, "/sbin/modprobe",
+                                                       false, false);
+                initialized = true;
+        }
+
+        /* Get tomoyo_realpath of program. */
+        retval = -ENOENT;
+        /* I hope tomoyo_realpath() won't fail with -ENOMEM. */
+        real_program_name = tomoyo_realpath(original_name);
+        if (!real_program_name)
+                goto out;
+        /* Get tomoyo_realpath of symbolic link. */
+        symlink_program_name = tomoyo_realpath_nofollow(original_name);
+        if (!symlink_program_name)
+                goto out;
+
+        r.name = real_program_name;
+        tomoyo_fill_path_info(&r);
+        s.name = symlink_program_name;
+        tomoyo_fill_path_info(&s);
+        l.name = tomoyo_get_last_name(old_domain);
+        tomoyo_fill_path_info(&l);
+
+        /* Check 'alias' directive. */
+        if (tomoyo_pathcmp(&r, &s)) {
+                struct tomoyo_alias_entry *ptr;
+                /* Is this program allowed to be called via symbolic links? */
+                down_read(&tomoyo_alias_list_lock);
+                list_for_each_entry(ptr, &tomoyo_alias_list, list) {
+                        if (ptr->is_deleted ||
+                            tomoyo_pathcmp(&r, ptr->original_name) ||
+                            tomoyo_pathcmp(&s, ptr->aliased_name))
+                                continue;
+                        memset(real_program_name, 0, TOMOYO_MAX_PATHNAME_LEN);
+                        strncpy(real_program_name, ptr->aliased_name->name,
+                                TOMOYO_MAX_PATHNAME_LEN - 1);
+                        tomoyo_fill_path_info(&r);
+                        break;
+                }
+                up_read(&tomoyo_alias_list_lock);
+        }
+
+        /* Check execute permission. */
+        retval = tomoyo_check_exec_perm(old_domain, &r, tmp);
+        if (retval < 0)
+                goto out;
+
+        new_domain_name = tmp->buffer;
+        if (tomoyo_is_domain_initializer(old_domain->domainname, &r, &l)) {
+                /* Transit to the child of tomoyo_kernel_domain domain. */
+                snprintf(new_domain_name, TOMOYO_MAX_PATHNAME_LEN + 1,
+                         TOMOYO_ROOT_NAME " " "%s", real_program_name);
+        } else 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;
+        } else if (tomoyo_is_domain_keeper(old_domain->domainname, &r, &l)) {
+                /* Keep current domain. */
+                domain = old_domain;
+        } else {
+                /* Normal domain transition. */
+                snprintf(new_domain_name, TOMOYO_MAX_PATHNAME_LEN + 1,
+                         "%s %s", old_domain_name, real_program_name);
+        }
+        if (domain || strlen(new_domain_name) >= TOMOYO_MAX_PATHNAME_LEN)
+                goto done;
+        down_read(&tomoyo_domain_list_lock);
+        domain = tomoyo_find_domain(new_domain_name);
+        up_read(&tomoyo_domain_list_lock);
+        if (domain)
+                goto done;
+        if (is_enforce)
+                goto done;
+        domain = tomoyo_find_or_assign_new_domain(new_domain_name,
+                                                  old_domain->profile);
+ done:
+        if (domain)
+                goto out;
+        printk(KERN_WARNING "TOMOYO-ERROR: Domain '%s' not defined.\n",
+               new_domain_name);
+        if (is_enforce)
+                retval = -EPERM;
+        else
+                tomoyo_set_domain_flag(old_domain, false,
+                                       TOMOYO_DOMAIN_FLAGS_TRANSITION_FAILED);
+ out:
+        tomoyo_free(real_program_name);
+        tomoyo_free(symlink_program_name);
+        *next_domain = domain ? domain : old_domain;
+        tomoyo_free(tmp);
+        return retval;
+}