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[linux-2.6/linux-2.6-openrd.git] / security / tomoyo / domain.c

/*
 * 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 = true;

        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;
}