TOMOYO: Several fixes for TOMOYO's management programs.

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / security / tomoyo / common.c

/*
 * security/tomoyo/common.c
 *
 * Common functions for TOMOYO.
 *
 * Copyright (C) 2005-2010  NTT DATA CORPORATION
 */

#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/security.h>
#include <linux/hardirq.h>
#include "common.h"

/* String table for functionality that takes 4 modes. */
static const char *tomoyo_mode_4[4] = {
        "disabled", "learning", "permissive", "enforcing"
};
/* String table for functionality that takes 2 modes. */
static const char *tomoyo_mode_2[4] = {
        "disabled", "enabled", "enabled", "enabled"
};

/*
 * tomoyo_control_array is a static data which contains
 *
 *  (1) functionality name used by /sys/kernel/security/tomoyo/profile .
 *  (2) initial values for "struct tomoyo_profile".
 *  (3) max values for "struct tomoyo_profile".
 */
static struct {
        const char *keyword;
        unsigned int current_value;
        const unsigned int max_value;
} tomoyo_control_array[TOMOYO_MAX_CONTROL_INDEX] = {
        [TOMOYO_MAC_FOR_FILE]     = { "MAC_FOR_FILE",        0,       3 },
        [TOMOYO_MAX_ACCEPT_ENTRY] = { "MAX_ACCEPT_ENTRY", 2048, INT_MAX },
        [TOMOYO_VERBOSE]          = { "TOMOYO_VERBOSE",      1,       1 },
};

/*
 * tomoyo_profile is a structure which is used for holding the mode of access
 * controls. TOMOYO has 4 modes: disabled, learning, permissive, enforcing.
 * An administrator can define up to 256 profiles.
 * The ->profile of "struct tomoyo_domain_info" is used for remembering
 * the profile's number (0 - 255) assigned to that domain.
 */
static struct tomoyo_profile {
        unsigned int value[TOMOYO_MAX_CONTROL_INDEX];
        const struct tomoyo_path_info *comment;
} *tomoyo_profile_ptr[TOMOYO_MAX_PROFILES];

/* Permit policy management by non-root user? */
static bool tomoyo_manage_by_non_root;

/* Utility functions. */

/**
 * tomoyo_print_name_union - Print a tomoyo_name_union.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 * @ptr:  Pointer to "struct tomoyo_name_union".
 *
 * Returns true on success, false otherwise.
 */
static bool tomoyo_print_name_union(struct tomoyo_io_buffer *head,
                                 const struct tomoyo_name_union *ptr)
{
        int pos = head->read_avail;
        if (pos && head->read_buf[pos - 1] == ' ')
                head->read_avail--;
        if (ptr->is_group)
                return tomoyo_io_printf(head, " @%s",
                                        ptr->group->group_name->name);
        return tomoyo_io_printf(head, " %s", ptr->filename->name);
}

/**
 * tomoyo_print_number_union - Print a tomoyo_number_union.
 *
 * @head:       Pointer to "struct tomoyo_io_buffer".
 * @ptr:        Pointer to "struct tomoyo_number_union".
 *
 * Returns true on success, false otherwise.
 */
bool tomoyo_print_number_union(struct tomoyo_io_buffer *head,
                               const struct tomoyo_number_union *ptr)
{
        unsigned long min;
        unsigned long max;
        u8 min_type;
        u8 max_type;
        if (!tomoyo_io_printf(head, " "))
                return false;
        if (ptr->is_group)
                return tomoyo_io_printf(head, "@%s",
                                        ptr->group->group_name->name);
        min_type = ptr->min_type;
        max_type = ptr->max_type;
        min = ptr->values[0];
        max = ptr->values[1];
        switch (min_type) {
        case TOMOYO_VALUE_TYPE_HEXADECIMAL:
                if (!tomoyo_io_printf(head, "0x%lX", min))
                        return false;
                break;
        case TOMOYO_VALUE_TYPE_OCTAL:
                if (!tomoyo_io_printf(head, "0%lo", min))
                        return false;
                break;
        default:
                if (!tomoyo_io_printf(head, "%lu", min))
                        return false;
                break;
        }
        if (min == max && min_type == max_type)
                return true;
        switch (max_type) {
        case TOMOYO_VALUE_TYPE_HEXADECIMAL:
                return tomoyo_io_printf(head, "-0x%lX", max);
        case TOMOYO_VALUE_TYPE_OCTAL:
                return tomoyo_io_printf(head, "-0%lo", max);
        default:
                return tomoyo_io_printf(head, "-%lu", max);
        }
}

/**
 * tomoyo_io_printf - Transactional printf() to "struct tomoyo_io_buffer" structure.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 * @fmt:  The printf()'s format string, followed by parameters.
 *
 * Returns true if output was written, false otherwise.
 *
 * The snprintf() will truncate, but tomoyo_io_printf() won't.
 */
bool tomoyo_io_printf(struct tomoyo_io_buffer *head, const char *fmt, ...)
{
        va_list args;
        int len;
        int pos = head->read_avail;
        int size = head->readbuf_size - pos;

        if (size <= 0)
                return false;
        va_start(args, fmt);
        len = vsnprintf(head->read_buf + pos, size, fmt, args);
        va_end(args);
        if (pos + len >= head->readbuf_size)
                return false;
        head->read_avail += len;
        return true;
}

/**
 * tomoyo_check_flags - Check mode for specified functionality.
 *
 * @domain: Pointer to "struct tomoyo_domain_info".
 * @index:  The functionality to check mode.
 *
 * TOMOYO checks only process context.
 * This code disables TOMOYO's enforcement in case the function is called from
 * interrupt context.
 */
unsigned int tomoyo_check_flags(const struct tomoyo_domain_info *domain,
                                const u8 index)
{
        const u8 profile = domain->profile;

        if (WARN_ON(in_interrupt()))
                return 0;
        return tomoyo_policy_loaded && index < TOMOYO_MAX_CONTROL_INDEX
#if TOMOYO_MAX_PROFILES != 256
                && profile < TOMOYO_MAX_PROFILES
#endif
                && tomoyo_profile_ptr[profile] ?
                tomoyo_profile_ptr[profile]->value[index] : 0;
}

/**
 * tomoyo_verbose_mode - Check whether TOMOYO is verbose mode.
 *
 * @domain: Pointer to "struct tomoyo_domain_info".
 *
 * Returns true if domain policy violation warning should be printed to
 * console.
 */
bool tomoyo_verbose_mode(const struct tomoyo_domain_info *domain)
{
        return tomoyo_check_flags(domain, TOMOYO_VERBOSE) != 0;
}

/**
 * tomoyo_find_or_assign_new_profile - Create a new profile.
 *
 * @profile: Profile number to create.
 *
 * Returns pointer to "struct tomoyo_profile" on success, NULL otherwise.
 */
static struct tomoyo_profile *tomoyo_find_or_assign_new_profile(const unsigned
                                                                int profile)
{
        struct tomoyo_profile *ptr = NULL;
        int i;

        if (profile >= TOMOYO_MAX_PROFILES)
                return NULL;
        if (mutex_lock_interruptible(&tomoyo_policy_lock))
                return NULL;
        ptr = tomoyo_profile_ptr[profile];
        if (ptr)
                goto ok;
        ptr = kmalloc(sizeof(*ptr), GFP_NOFS);
        if (!tomoyo_memory_ok(ptr)) {
                kfree(ptr);
                ptr = NULL;
                goto ok;
        }
        for (i = 0; i < TOMOYO_MAX_CONTROL_INDEX; i++)
                ptr->value[i] = tomoyo_control_array[i].current_value;
        mb(); /* Avoid out-of-order execution. */
        tomoyo_profile_ptr[profile] = ptr;
 ok:
        mutex_unlock(&tomoyo_policy_lock);
        return ptr;
}

/**
 * tomoyo_write_profile - Write to profile table.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_write_profile(struct tomoyo_io_buffer *head)
{
        char *data = head->write_buf;
        unsigned int i;
        unsigned int value;
        char *cp;
        struct tomoyo_profile *profile;
        unsigned long num;

        cp = strchr(data, '-');
        if (cp)
                *cp = '\0';
        if (strict_strtoul(data, 10, &num))
                return -EINVAL;
        if (cp)
                data = cp + 1;
        profile = tomoyo_find_or_assign_new_profile(num);
        if (!profile)
                return -EINVAL;
        cp = strchr(data, '=');
        if (!cp)
                return -EINVAL;
        *cp = '\0';
        if (!strcmp(data, "COMMENT")) {
                const struct tomoyo_path_info *old_comment = profile->comment;
                profile->comment = tomoyo_get_name(cp + 1);
                tomoyo_put_name(old_comment);
                return 0;
        }
        for (i = 0; i < TOMOYO_MAX_CONTROL_INDEX; i++) {
                if (strcmp(data, tomoyo_control_array[i].keyword))
                        continue;
                if (sscanf(cp + 1, "%u", &value) != 1) {
                        int j;
                        const char **modes;
                        switch (i) {
                        case TOMOYO_VERBOSE:
                                modes = tomoyo_mode_2;
                                break;
                        default:
                                modes = tomoyo_mode_4;
                                break;
                        }
                        for (j = 0; j < 4; j++) {
                                if (strcmp(cp + 1, modes[j]))
                                        continue;
                                value = j;
                                break;
                        }
                        if (j == 4)
                                return -EINVAL;
                } else if (value > tomoyo_control_array[i].max_value) {
                        value = tomoyo_control_array[i].max_value;
                }
                profile->value[i] = value;
                return 0;
        }
        return -EINVAL;
}

/**
 * tomoyo_read_profile - Read from profile table.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns 0.
 */
static int tomoyo_read_profile(struct tomoyo_io_buffer *head)
{
        static const int total = TOMOYO_MAX_CONTROL_INDEX + 1;
        int step;

        if (head->read_eof)
                return 0;
        for (step = head->read_step; step < TOMOYO_MAX_PROFILES * total;
             step++) {
                const u8 index = step / total;
                u8 type = step % total;
                const struct tomoyo_profile *profile
                        = tomoyo_profile_ptr[index];
                head->read_step = step;
                if (!profile)
                        continue;
                if (!type) { /* Print profile' comment tag. */
                        if (!tomoyo_io_printf(head, "%u-COMMENT=%s\n",
                                              index, profile->comment ?
                                              profile->comment->name : ""))
                                break;
                        continue;
                }
                type--;
                if (type < TOMOYO_MAX_CONTROL_INDEX) {
                        const unsigned int value = profile->value[type];
                        const char **modes = NULL;
                        const char *keyword
                                = tomoyo_control_array[type].keyword;
                        switch (tomoyo_control_array[type].max_value) {
                        case 3:
                                modes = tomoyo_mode_4;
                                break;
                        case 1:
                                modes = tomoyo_mode_2;
                                break;
                        }
                        if (modes) {
                                if (!tomoyo_io_printf(head, "%u-%s=%s\n", index,
                                                      keyword, modes[value]))
                                        break;
                        } else {
                                if (!tomoyo_io_printf(head, "%u-%s=%u\n", index,
                                                      keyword, value))
                                        break;
                        }
                }
        }
        if (step == TOMOYO_MAX_PROFILES * total)
                head->read_eof = true;
        return 0;
}

/*
 * tomoyo_policy_manager_list is used for holding list of domainnames or
 * programs which are permitted to modify configuration via
 * /sys/kernel/security/tomoyo/ interface.
 *
 * An entry is added by
 *
 * # echo '<kernel> /sbin/mingetty /bin/login /bin/bash' > \
 *                                        /sys/kernel/security/tomoyo/manager
 *  (if you want to specify by a domainname)
 *
 *  or
 *
 * # echo '/usr/sbin/tomoyo-editpolicy' > /sys/kernel/security/tomoyo/manager
 *  (if you want to specify by a program's location)
 *
 * and is deleted by
 *
 * # echo 'delete <kernel> /sbin/mingetty /bin/login /bin/bash' > \
 *                                        /sys/kernel/security/tomoyo/manager
 *
 *  or
 *
 * # echo 'delete /usr/sbin/tomoyo-editpolicy' > \
 *                                        /sys/kernel/security/tomoyo/manager
 *
 * and all entries are retrieved by
 *
 * # cat /sys/kernel/security/tomoyo/manager
 */
LIST_HEAD(tomoyo_policy_manager_list);

/**
 * tomoyo_update_manager_entry - Add a manager entry.
 *
 * @manager:   The path to manager or the domainnamme.
 * @is_delete: True if it is a delete request.
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
static int tomoyo_update_manager_entry(const char *manager,
                                       const bool is_delete)
{
        struct tomoyo_policy_manager_entry *ptr;
        struct tomoyo_policy_manager_entry e = { };
        int error = is_delete ? -ENOENT : -ENOMEM;

        if (tomoyo_is_domain_def(manager)) {
                if (!tomoyo_is_correct_domain(manager))
                        return -EINVAL;
                e.is_domain = true;
        } else {
                if (!tomoyo_is_correct_path(manager, 1, -1, -1))
                        return -EINVAL;
        }
        e.manager = tomoyo_get_name(manager);
        if (!e.manager)
                return -ENOMEM;
        if (mutex_lock_interruptible(&tomoyo_policy_lock))
                goto out;
        list_for_each_entry_rcu(ptr, &tomoyo_policy_manager_list, list) {
                if (ptr->manager != e.manager)
                        continue;
                ptr->is_deleted = is_delete;
                error = 0;
                break;
        }
        if (!is_delete && error) {
                struct tomoyo_policy_manager_entry *entry =
                        tomoyo_commit_ok(&e, sizeof(e));
                if (entry) {
                        list_add_tail_rcu(&entry->list,
                                          &tomoyo_policy_manager_list);
                        error = 0;
                }
        }
        mutex_unlock(&tomoyo_policy_lock);
 out:
        tomoyo_put_name(e.manager);
        return error;
}

/**
 * tomoyo_write_manager_policy - Write manager policy.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
static int tomoyo_write_manager_policy(struct tomoyo_io_buffer *head)
{
        char *data = head->write_buf;
        bool is_delete = tomoyo_str_starts(&data, TOMOYO_KEYWORD_DELETE);

        if (!strcmp(data, "manage_by_non_root")) {
                tomoyo_manage_by_non_root = !is_delete;
                return 0;
        }
        return tomoyo_update_manager_entry(data, is_delete);
}

/**
 * tomoyo_read_manager_policy - Read manager policy.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns 0.
 *
 * Caller holds tomoyo_read_lock().
 */
static int tomoyo_read_manager_policy(struct tomoyo_io_buffer *head)
{
        struct list_head *pos;
        bool done = true;

        if (head->read_eof)
                return 0;
        list_for_each_cookie(pos, head->read_var2,
                             &tomoyo_policy_manager_list) {
                struct tomoyo_policy_manager_entry *ptr;
                ptr = list_entry(pos, struct tomoyo_policy_manager_entry,
                                 list);
                if (ptr->is_deleted)
                        continue;
                done = tomoyo_io_printf(head, "%s\n", ptr->manager->name);
                if (!done)
                        break;
        }
        head->read_eof = done;
        return 0;
}

/**
 * tomoyo_is_policy_manager - Check whether the current process is a policy manager.
 *
 * Returns true if the current process is permitted to modify policy
 * via /sys/kernel/security/tomoyo/ interface.
 *
 * Caller holds tomoyo_read_lock().
 */
static bool tomoyo_is_policy_manager(void)
{
        struct tomoyo_policy_manager_entry *ptr;
        const char *exe;
        const struct task_struct *task = current;
        const struct tomoyo_path_info *domainname = tomoyo_domain()->domainname;
        bool found = false;

        if (!tomoyo_policy_loaded)
                return true;
        if (!tomoyo_manage_by_non_root && (task->cred->uid || task->cred->euid))
                return false;
        list_for_each_entry_rcu(ptr, &tomoyo_policy_manager_list, list) {
                if (!ptr->is_deleted && ptr->is_domain
                    && !tomoyo_pathcmp(domainname, ptr->manager)) {
                        found = true;
                        break;
                }
        }
        if (found)
                return true;
        exe = tomoyo_get_exe();
        if (!exe)
                return false;
        list_for_each_entry_rcu(ptr, &tomoyo_policy_manager_list, list) {
                if (!ptr->is_deleted && !ptr->is_domain
                    && !strcmp(exe, ptr->manager->name)) {
                        found = true;
                        break;
                }
        }
        if (!found) { /* Reduce error messages. */
                static pid_t last_pid;
                const pid_t pid = current->pid;
                if (last_pid != pid) {
                        printk(KERN_WARNING "%s ( %s ) is not permitted to "
                               "update policies.\n", domainname->name, exe);
                        last_pid = pid;
                }
        }
        kfree(exe);
        return found;
}

/**
 * tomoyo_is_select_one - Parse select command.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 * @data: String to parse.
 *
 * Returns true on success, false otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
static bool tomoyo_is_select_one(struct tomoyo_io_buffer *head,
                                 const char *data)
{
        unsigned int pid;
        struct tomoyo_domain_info *domain = NULL;
        bool global_pid = false;

        if (sscanf(data, "pid=%u", &pid) == 1 ||
            (global_pid = true, sscanf(data, "global-pid=%u", &pid) == 1)) {
                struct task_struct *p;
                rcu_read_lock();
                read_lock(&tasklist_lock);
                if (global_pid)
                        p = find_task_by_pid_ns(pid, &init_pid_ns);
                else
                        p = find_task_by_vpid(pid);
                if (p)
                        domain = tomoyo_real_domain(p);
                read_unlock(&tasklist_lock);
                rcu_read_unlock();
        } else if (!strncmp(data, "domain=", 7)) {
                if (tomoyo_is_domain_def(data + 7))
                        domain = tomoyo_find_domain(data + 7);
        } else
                return false;
        head->write_var1 = domain;
        /* Accessing read_buf is safe because head->io_sem is held. */
        if (!head->read_buf)
                return true; /* Do nothing if open(O_WRONLY). */
        head->read_avail = 0;
        tomoyo_io_printf(head, "# select %s\n", data);
        head->read_single_domain = true;
        head->read_eof = !domain;
        if (domain) {
                struct tomoyo_domain_info *d;
                head->read_var1 = NULL;
                list_for_each_entry_rcu(d, &tomoyo_domain_list, list) {
                        if (d == domain)
                                break;
                        head->read_var1 = &d->list;
                }
                head->read_var2 = NULL;
                head->read_bit = 0;
                head->read_step = 0;
                if (domain->is_deleted)
                        tomoyo_io_printf(head, "# This is a deleted domain.\n");
        }
        return true;
}

/**
 * tomoyo_delete_domain - Delete a domain.
 *
 * @domainname: The name of domain.
 *
 * Returns 0.
 *
 * Caller holds tomoyo_read_lock().
 */
static int tomoyo_delete_domain(char *domainname)
{
        struct tomoyo_domain_info *domain;
        struct tomoyo_path_info name;

        name.name = domainname;
        tomoyo_fill_path_info(&name);
        if (mutex_lock_interruptible(&tomoyo_policy_lock))
                return 0;
        /* Is there an active domain? */
        list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
                /* Never delete tomoyo_kernel_domain */
                if (domain == &tomoyo_kernel_domain)
                        continue;
                if (domain->is_deleted ||
                    tomoyo_pathcmp(domain->domainname, &name))
                        continue;
                domain->is_deleted = true;
                break;
        }
        mutex_unlock(&tomoyo_policy_lock);
        return 0;
}

/**
 * tomoyo_write_domain_policy2 - Write domain policy.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
static int tomoyo_write_domain_policy2(char *data,
                                       struct tomoyo_domain_info *domain,
                                       const bool is_delete)
{
        if (tomoyo_str_starts(&data, TOMOYO_KEYWORD_ALLOW_MOUNT))
                return tomoyo_write_mount_policy(data, domain, is_delete);
        return tomoyo_write_file_policy(data, domain, is_delete);
}

/**
 * tomoyo_write_domain_policy - Write domain policy.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
static int tomoyo_write_domain_policy(struct tomoyo_io_buffer *head)
{
        char *data = head->write_buf;
        struct tomoyo_domain_info *domain = head->write_var1;
        bool is_delete = false;
        bool is_select = false;
        unsigned int profile;

        if (tomoyo_str_starts(&data, TOMOYO_KEYWORD_DELETE))
                is_delete = true;
        else if (tomoyo_str_starts(&data, TOMOYO_KEYWORD_SELECT))
                is_select = true;
        if (is_select && tomoyo_is_select_one(head, data))
                return 0;
        /* Don't allow updating policies by non manager programs. */
        if (!tomoyo_is_policy_manager())
                return -EPERM;
        if (tomoyo_is_domain_def(data)) {
                domain = NULL;
                if (is_delete)
                        tomoyo_delete_domain(data);
                else if (is_select)
                        domain = tomoyo_find_domain(data);
                else
                        domain = tomoyo_find_or_assign_new_domain(data, 0);
                head->write_var1 = domain;
                return 0;
        }
        if (!domain)
                return -EINVAL;

        if (sscanf(data, TOMOYO_KEYWORD_USE_PROFILE "%u", &profile) == 1
            && profile < TOMOYO_MAX_PROFILES) {
                if (tomoyo_profile_ptr[profile] || !tomoyo_policy_loaded)
                        domain->profile = (u8) profile;
                return 0;
        }
        if (!strcmp(data, TOMOYO_KEYWORD_IGNORE_GLOBAL_ALLOW_READ)) {
                domain->ignore_global_allow_read = !is_delete;
                return 0;
        }
        if (!strcmp(data, TOMOYO_KEYWORD_QUOTA_EXCEEDED)) {
                domain->quota_warned = !is_delete;
                return 0;
        }
        if (!strcmp(data, TOMOYO_KEYWORD_TRANSITION_FAILED)) {
                domain->transition_failed = !is_delete;
                return 0;
        }
        return tomoyo_write_domain_policy2(data, domain, is_delete);
}

/**
 * tomoyo_print_path_acl - Print a single path ACL entry.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 * @ptr:  Pointer to "struct tomoyo_path_acl".
 *
 * Returns true on success, false otherwise.
 */
static bool tomoyo_print_path_acl(struct tomoyo_io_buffer *head,
                                  struct tomoyo_path_acl *ptr)
{
        int pos;
        u8 bit;
        const u16 perm = ptr->perm;

        for (bit = head->read_bit; bit < TOMOYO_MAX_PATH_OPERATION; bit++) {
                if (!(perm & (1 << bit)))
                        continue;
                /* Print "read/write" instead of "read" and "write". */
                if ((bit == TOMOYO_TYPE_READ || bit == TOMOYO_TYPE_WRITE)
                    && (perm & (1 << TOMOYO_TYPE_READ_WRITE)))
                        continue;
                pos = head->read_avail;
                if (!tomoyo_io_printf(head, "allow_%s ",
                                      tomoyo_path2keyword(bit)) ||
                    !tomoyo_print_name_union(head, &ptr->name) ||
                    !tomoyo_io_printf(head, "\n"))
                        goto out;
        }
        head->read_bit = 0;
        return true;
 out:
        head->read_bit = bit;
        head->read_avail = pos;
        return false;
}

/**
 * tomoyo_print_path2_acl - Print a double path ACL entry.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 * @ptr:  Pointer to "struct tomoyo_path2_acl".
 *
 * Returns true on success, false otherwise.
 */
static bool tomoyo_print_path2_acl(struct tomoyo_io_buffer *head,
                                   struct tomoyo_path2_acl *ptr)
{
        int pos;
        const u8 perm = ptr->perm;
        u8 bit;

        for (bit = head->read_bit; bit < TOMOYO_MAX_PATH2_OPERATION; bit++) {
                if (!(perm & (1 << bit)))
                        continue;
                pos = head->read_avail;
                if (!tomoyo_io_printf(head, "allow_%s ",
                                      tomoyo_path22keyword(bit)) ||
                    !tomoyo_print_name_union(head, &ptr->name1) ||
                    !tomoyo_print_name_union(head, &ptr->name2) ||
                    !tomoyo_io_printf(head, "\n"))
                        goto out;
        }
        head->read_bit = 0;
        return true;
 out:
        head->read_bit = bit;
        head->read_avail = pos;
        return false;
}

/**
 * tomoyo_print_path_number_acl - Print a path_number ACL entry.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 * @ptr:  Pointer to "struct tomoyo_path_number_acl".
 *
 * Returns true on success, false otherwise.
 */
static bool tomoyo_print_path_number_acl(struct tomoyo_io_buffer *head,
                                         struct tomoyo_path_number_acl *ptr)
{
        int pos;
        u8 bit;
        const u8 perm = ptr->perm;
        for (bit = head->read_bit; bit < TOMOYO_MAX_PATH_NUMBER_OPERATION;
             bit++) {
                if (!(perm & (1 << bit)))
                        continue;
                pos = head->read_avail;
                if (!tomoyo_io_printf(head, "allow_%s",
                                      tomoyo_path_number2keyword(bit)) ||
                    !tomoyo_print_name_union(head, &ptr->name) ||
                    !tomoyo_print_number_union(head, &ptr->number) ||
                    !tomoyo_io_printf(head, "\n"))
                        goto out;
        }
        head->read_bit = 0;
        return true;
 out:
        head->read_bit = bit;
        head->read_avail = pos;
        return false;
}

/**
 * tomoyo_print_path_number3_acl - Print a path_number3 ACL entry.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 * @ptr:  Pointer to "struct tomoyo_path_number3_acl".
 *
 * Returns true on success, false otherwise.
 */
static bool tomoyo_print_path_number3_acl(struct tomoyo_io_buffer *head,
                                          struct tomoyo_path_number3_acl *ptr)
{
        int pos;
        u8 bit;
        const u16 perm = ptr->perm;
        for (bit = head->read_bit; bit < TOMOYO_MAX_PATH_NUMBER3_OPERATION;
             bit++) {
                if (!(perm & (1 << bit)))
                        continue;
                pos = head->read_avail;
                if (!tomoyo_io_printf(head, "allow_%s",
                                      tomoyo_path_number32keyword(bit)) ||
                    !tomoyo_print_name_union(head, &ptr->name) ||
                    !tomoyo_print_number_union(head, &ptr->mode) ||
                    !tomoyo_print_number_union(head, &ptr->major) ||
                    !tomoyo_print_number_union(head, &ptr->minor) ||
                    !tomoyo_io_printf(head, "\n"))
                        goto out;
        }
        head->read_bit = 0;
        return true;
 out:
        head->read_bit = bit;
        head->read_avail = pos;
        return false;
}

/**
 * tomoyo_print_mount_acl - Print a mount ACL entry.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 * @ptr:  Pointer to "struct tomoyo_mount_acl".
 *
 * Returns true on success, false otherwise.
 */
static bool tomoyo_print_mount_acl(struct tomoyo_io_buffer *head,
                                   struct tomoyo_mount_acl *ptr)
{
        const int pos = head->read_avail;
        if (ptr->is_deleted)
                return true;
        if (!tomoyo_io_printf(head, TOMOYO_KEYWORD_ALLOW_MOUNT) ||
            !tomoyo_print_name_union(head, &ptr->dev_name) ||
            !tomoyo_print_name_union(head, &ptr->dir_name) ||
            !tomoyo_print_name_union(head, &ptr->fs_type) ||
            !tomoyo_print_number_union(head, &ptr->flags) ||
            !tomoyo_io_printf(head, "\n")) {
                head->read_avail = pos;
                return false;
        }
        return true;
}

/**
 * tomoyo_print_entry - Print an ACL entry.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 * @ptr:  Pointer to an ACL entry.
 *
 * Returns true on success, false otherwise.
 */
static bool tomoyo_print_entry(struct tomoyo_io_buffer *head,
                               struct tomoyo_acl_info *ptr)
{
        const u8 acl_type = ptr->type;

        if (acl_type == TOMOYO_TYPE_PATH_ACL) {
                struct tomoyo_path_acl *acl
                        = container_of(ptr, struct tomoyo_path_acl, head);
                return tomoyo_print_path_acl(head, acl);
        }
        if (acl_type == TOMOYO_TYPE_PATH2_ACL) {
                struct tomoyo_path2_acl *acl
                        = container_of(ptr, struct tomoyo_path2_acl, head);
                return tomoyo_print_path2_acl(head, acl);
        }
        if (acl_type == TOMOYO_TYPE_PATH_NUMBER_ACL) {
                struct tomoyo_path_number_acl *acl
                        = container_of(ptr, struct tomoyo_path_number_acl,
                                       head);
                return tomoyo_print_path_number_acl(head, acl);
        }
        if (acl_type == TOMOYO_TYPE_PATH_NUMBER3_ACL) {
                struct tomoyo_path_number3_acl *acl
                        = container_of(ptr, struct tomoyo_path_number3_acl,
                                       head);
                return tomoyo_print_path_number3_acl(head, acl);
        }
        if (acl_type == TOMOYO_TYPE_MOUNT_ACL) {
                struct tomoyo_mount_acl *acl
                        = container_of(ptr, struct tomoyo_mount_acl, head);
                return tomoyo_print_mount_acl(head, acl);
        }
        BUG(); /* This must not happen. */
        return false;
}

/**
 * tomoyo_read_domain_policy - Read domain policy.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns 0.
 *
 * Caller holds tomoyo_read_lock().
 */
static int tomoyo_read_domain_policy(struct tomoyo_io_buffer *head)
{
        struct list_head *dpos;
        struct list_head *apos;
        bool done = true;

        if (head->read_eof)
                return 0;
        if (head->read_step == 0)
                head->read_step = 1;
        list_for_each_cookie(dpos, head->read_var1, &tomoyo_domain_list) {
                struct tomoyo_domain_info *domain;
                const char *quota_exceeded = "";
                const char *transition_failed = "";
                const char *ignore_global_allow_read = "";
                domain = list_entry(dpos, struct tomoyo_domain_info, list);
                if (head->read_step != 1)
                        goto acl_loop;
                if (domain->is_deleted && !head->read_single_domain)
                        continue;
                /* Print domainname and flags. */
                if (domain->quota_warned)
                        quota_exceeded = "quota_exceeded\n";
                if (domain->transition_failed)
                        transition_failed = "transition_failed\n";
                if (domain->ignore_global_allow_read)
                        ignore_global_allow_read
                                = TOMOYO_KEYWORD_IGNORE_GLOBAL_ALLOW_READ "\n";
                done = tomoyo_io_printf(head, "%s\n" TOMOYO_KEYWORD_USE_PROFILE
                                        "%u\n%s%s%s\n",
                                        domain->domainname->name,
                                        domain->profile, quota_exceeded,
                                        transition_failed,
                                        ignore_global_allow_read);
                if (!done)
                        break;
                head->read_step = 2;
acl_loop:
                if (head->read_step == 3)
                        goto tail_mark;
                /* Print ACL entries in the domain. */
                list_for_each_cookie(apos, head->read_var2,
                                     &domain->acl_info_list) {
                        struct tomoyo_acl_info *ptr
                                = list_entry(apos, struct tomoyo_acl_info,
                                             list);
                        done = tomoyo_print_entry(head, ptr);
                        if (!done)
                                break;
                }
                if (!done)
                        break;
                head->read_step = 3;
tail_mark:
                done = tomoyo_io_printf(head, "\n");
                if (!done)
                        break;
                head->read_step = 1;
                if (head->read_single_domain)
                        break;
        }
        head->read_eof = done;
        return 0;
}

/**
 * tomoyo_write_domain_profile - Assign profile for specified domain.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns 0 on success, -EINVAL otherwise.
 *
 * This is equivalent to doing
 *
 *     ( echo "select " $domainname; echo "use_profile " $profile ) |
 *     /usr/sbin/tomoyo-loadpolicy -d
 *
 * Caller holds tomoyo_read_lock().
 */
static int tomoyo_write_domain_profile(struct tomoyo_io_buffer *head)
{
        char *data = head->write_buf;
        char *cp = strchr(data, ' ');
        struct tomoyo_domain_info *domain;
        unsigned long profile;

        if (!cp)
                return -EINVAL;
        *cp = '\0';
        domain = tomoyo_find_domain(cp + 1);
        if (strict_strtoul(data, 10, &profile))
                return -EINVAL;
        if (domain && profile < TOMOYO_MAX_PROFILES
            && (tomoyo_profile_ptr[profile] || !tomoyo_policy_loaded))
                domain->profile = (u8) profile;
        return 0;
}

/**
 * tomoyo_read_domain_profile - Read only domainname and profile.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns list of profile number and domainname pairs.
 *
 * This is equivalent to doing
 *
 *     grep -A 1 '^<kernel>' /sys/kernel/security/tomoyo/domain_policy |
 *     awk ' { if ( domainname == "" ) { if ( $1 == "<kernel>" )
 *     domainname = $0; } else if ( $1 == "use_profile" ) {
 *     print $2 " " domainname; domainname = ""; } } ; '
 *
 * Caller holds tomoyo_read_lock().
 */
static int tomoyo_read_domain_profile(struct tomoyo_io_buffer *head)
{
        struct list_head *pos;
        bool done = true;

        if (head->read_eof)
                return 0;
        list_for_each_cookie(pos, head->read_var1, &tomoyo_domain_list) {
                struct tomoyo_domain_info *domain;
                domain = list_entry(pos, struct tomoyo_domain_info, list);
                if (domain->is_deleted)
                        continue;
                done = tomoyo_io_printf(head, "%u %s\n", domain->profile,
                                        domain->domainname->name);
                if (!done)
                        break;
        }
        head->read_eof = done;
        return 0;
}

/**
 * tomoyo_write_pid: Specify PID to obtain domainname.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns 0.
 */
static int tomoyo_write_pid(struct tomoyo_io_buffer *head)
{
        unsigned long pid;
        /* No error check. */
        strict_strtoul(head->write_buf, 10, &pid);
        head->read_step = (int) pid;
        head->read_eof = false;
        return 0;
}

/**
 * tomoyo_read_pid - Get domainname of the specified PID.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns the domainname which the specified PID is in on success,
 * empty string otherwise.
 * The PID is specified by tomoyo_write_pid() so that the user can obtain
 * using read()/write() interface rather than sysctl() interface.
 */
static int tomoyo_read_pid(struct tomoyo_io_buffer *head)
{
        if (head->read_avail == 0 && !head->read_eof) {
                const int pid = head->read_step;
                struct task_struct *p;
                struct tomoyo_domain_info *domain = NULL;
                rcu_read_lock();
                read_lock(&tasklist_lock);
                p = find_task_by_vpid(pid);
                if (p)
                        domain = tomoyo_real_domain(p);
                read_unlock(&tasklist_lock);
                rcu_read_unlock();
                if (domain)
                        tomoyo_io_printf(head, "%d %u %s", pid, domain->profile,
                                         domain->domainname->name);
                head->read_eof = true;
        }
        return 0;
}

/**
 * tomoyo_write_exception_policy - Write exception policy.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
static int tomoyo_write_exception_policy(struct tomoyo_io_buffer *head)
{
        char *data = head->write_buf;
        bool is_delete = tomoyo_str_starts(&data, TOMOYO_KEYWORD_DELETE);

        if (tomoyo_str_starts(&data, TOMOYO_KEYWORD_KEEP_DOMAIN))
                return tomoyo_write_domain_keeper_policy(data, false,
                                                         is_delete);
        if (tomoyo_str_starts(&data, TOMOYO_KEYWORD_NO_KEEP_DOMAIN))
                return tomoyo_write_domain_keeper_policy(data, true, is_delete);
        if (tomoyo_str_starts(&data, TOMOYO_KEYWORD_INITIALIZE_DOMAIN))
                return tomoyo_write_domain_initializer_policy(data, false,
                                                              is_delete);
        if (tomoyo_str_starts(&data, TOMOYO_KEYWORD_NO_INITIALIZE_DOMAIN))
                return tomoyo_write_domain_initializer_policy(data, true,
                                                              is_delete);
        if (tomoyo_str_starts(&data, TOMOYO_KEYWORD_ALIAS))
                return tomoyo_write_alias_policy(data, is_delete);
        if (tomoyo_str_starts(&data, TOMOYO_KEYWORD_ALLOW_READ))
                return tomoyo_write_globally_readable_policy(data, is_delete);
        if (tomoyo_str_starts(&data, TOMOYO_KEYWORD_FILE_PATTERN))
                return tomoyo_write_pattern_policy(data, is_delete);
        if (tomoyo_str_starts(&data, TOMOYO_KEYWORD_DENY_REWRITE))
                return tomoyo_write_no_rewrite_policy(data, is_delete);
        if (tomoyo_str_starts(&data, TOMOYO_KEYWORD_PATH_GROUP))
                return tomoyo_write_path_group_policy(data, is_delete);
        if (tomoyo_str_starts(&data, TOMOYO_KEYWORD_NUMBER_GROUP))
                return tomoyo_write_number_group_policy(data, is_delete);
        return -EINVAL;
}

/**
 * tomoyo_read_exception_policy - Read exception policy.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns 0 on success, -EINVAL otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
static int tomoyo_read_exception_policy(struct tomoyo_io_buffer *head)
{
        if (!head->read_eof) {
                switch (head->read_step) {
                case 0:
                        head->read_var2 = NULL;
                        head->read_step = 1;
                case 1:
                        if (!tomoyo_read_domain_keeper_policy(head))
                                break;
                        head->read_var2 = NULL;
                        head->read_step = 2;
                case 2:
                        if (!tomoyo_read_globally_readable_policy(head))
                                break;
                        head->read_var2 = NULL;
                        head->read_step = 3;
                case 3:
                        head->read_var2 = NULL;
                        head->read_step = 4;
                case 4:
                        if (!tomoyo_read_domain_initializer_policy(head))
                                break;
                        head->read_var2 = NULL;
                        head->read_step = 5;
                case 5:
                        if (!tomoyo_read_alias_policy(head))
                                break;
                        head->read_var2 = NULL;
                        head->read_step = 6;
                case 6:
                        head->read_var2 = NULL;
                        head->read_step = 7;
                case 7:
                        if (!tomoyo_read_file_pattern(head))
                                break;
                        head->read_var2 = NULL;
                        head->read_step = 8;
                case 8:
                        if (!tomoyo_read_no_rewrite_policy(head))
                                break;
                        head->read_var2 = NULL;
                        head->read_step = 9;
                case 9:
                        if (!tomoyo_read_path_group_policy(head))
                                break;
                        head->read_var1 = NULL;
                        head->read_var2 = NULL;
                        head->read_step = 10;
                case 10:
                        if (!tomoyo_read_number_group_policy(head))
                                break;
                        head->read_var1 = NULL;
                        head->read_var2 = NULL;
                        head->read_step = 11;
                case 11:
                        head->read_eof = true;
                        break;
                default:
                        return -EINVAL;
                }
        }
        return 0;
}

/**
 * tomoyo_print_header - Get header line of audit log.
 *
 * @r: Pointer to "struct tomoyo_request_info".
 *
 * Returns string representation.
 *
 * This function uses kmalloc(), so caller must kfree() if this function
 * didn't return NULL.
 */
static char *tomoyo_print_header(struct tomoyo_request_info *r)
{
        static const char *tomoyo_mode_4[4] = {
                "disabled", "learning", "permissive", "enforcing"
        };
        struct timeval tv;
        const pid_t gpid = task_pid_nr(current);
        static const int tomoyo_buffer_len = 4096;
        char *buffer = kmalloc(tomoyo_buffer_len, GFP_NOFS);
        if (!buffer)
                return NULL;
        do_gettimeofday(&tv);
        snprintf(buffer, tomoyo_buffer_len - 1,
                 "#timestamp=%lu profile=%u mode=%s (global-pid=%u)"
                 " task={ pid=%u ppid=%u uid=%u gid=%u euid=%u"
                 " egid=%u suid=%u sgid=%u fsuid=%u fsgid=%u }",
                 tv.tv_sec, r->profile, tomoyo_mode_4[r->mode], gpid,
                 (pid_t) sys_getpid(), (pid_t) sys_getppid(),
                 current_uid(), current_gid(), current_euid(),
                 current_egid(), current_suid(), current_sgid(),
                 current_fsuid(), current_fsgid());
        return buffer;
}

/**
 * tomoyo_init_audit_log - Allocate buffer for audit logs.
 *
 * @len: Required size.
 * @r:   Pointer to "struct tomoyo_request_info".
 *
 * Returns pointer to allocated memory.
 *
 * The @len is updated to add the header lines' size on success.
 *
 * This function uses kzalloc(), so caller must kfree() if this function
 * didn't return NULL.
 */
static char *tomoyo_init_audit_log(int *len, struct tomoyo_request_info *r)
{
        char *buf = NULL;
        const char *header;
        const char *domainname;
        if (!r->domain)
                r->domain = tomoyo_domain();
        domainname = r->domain->domainname->name;
        header = tomoyo_print_header(r);
        if (!header)
                return NULL;
        *len += strlen(domainname) + strlen(header) + 10;
        buf = kzalloc(*len, GFP_NOFS);
        if (buf)
                snprintf(buf, (*len) - 1, "%s\n%s\n", header, domainname);
        kfree(header);
        return buf;
}

/* Wait queue for tomoyo_query_list. */
static DECLARE_WAIT_QUEUE_HEAD(tomoyo_query_wait);

/* Lock for manipulating tomoyo_query_list. */
static DEFINE_SPINLOCK(tomoyo_query_list_lock);

/* Structure for query. */
struct tomoyo_query_entry {
        struct list_head list;
        char *query;
        int query_len;
        unsigned int serial;
        int timer;
        int answer;
};

/* The list for "struct tomoyo_query_entry". */
static LIST_HEAD(tomoyo_query_list);

/*
 * Number of "struct file" referring /sys/kernel/security/tomoyo/query
 * interface.
 */
static atomic_t tomoyo_query_observers = ATOMIC_INIT(0);

/**
 * tomoyo_supervisor - Ask for the supervisor's decision.
 *
 * @r:       Pointer to "struct tomoyo_request_info".
 * @fmt:     The printf()'s format string, followed by parameters.
 *
 * Returns 0 if the supervisor decided to permit the access request which
 * violated the policy in enforcing mode, TOMOYO_RETRY_REQUEST if the
 * supervisor decided to retry the access request which violated the policy in
 * enforcing mode, 0 if it is not in enforcing mode, -EPERM otherwise.
 */
int tomoyo_supervisor(struct tomoyo_request_info *r, const char *fmt, ...)
{
        va_list args;
        int error = -EPERM;
        int pos;
        int len;
        static unsigned int tomoyo_serial;
        struct tomoyo_query_entry *tomoyo_query_entry = NULL;
        bool quota_exceeded = false;
        char *header;
        switch (r->mode) {
                char *buffer;
        case TOMOYO_CONFIG_LEARNING:
                if (!tomoyo_domain_quota_is_ok(r))
                        return 0;
                va_start(args, fmt);
                len = vsnprintf((char *) &pos, sizeof(pos) - 1, fmt, args) + 4;
                va_end(args);
                buffer = kmalloc(len, GFP_NOFS);
                if (!buffer)
                        return 0;
                va_start(args, fmt);
                vsnprintf(buffer, len - 1, fmt, args);
                va_end(args);
                tomoyo_normalize_line(buffer);
                tomoyo_write_domain_policy2(buffer, r->domain, false);
                kfree(buffer);
                /* fall through */
        case TOMOYO_CONFIG_PERMISSIVE:
                return 0;
        }
        if (!r->domain)
                r->domain = tomoyo_domain();
        if (!atomic_read(&tomoyo_query_observers))
                return -EPERM;
        va_start(args, fmt);
        len = vsnprintf((char *) &pos, sizeof(pos) - 1, fmt, args) + 32;
        va_end(args);
        header = tomoyo_init_audit_log(&len, r);
        if (!header)
                goto out;
        tomoyo_query_entry = kzalloc(sizeof(*tomoyo_query_entry), GFP_NOFS);
        if (!tomoyo_query_entry)
                goto out;
        tomoyo_query_entry->query = kzalloc(len, GFP_NOFS);
        if (!tomoyo_query_entry->query)
                goto out;
        len = ksize(tomoyo_query_entry->query);
        INIT_LIST_HEAD(&tomoyo_query_entry->list);
        spin_lock(&tomoyo_query_list_lock);
        if (tomoyo_quota_for_query && tomoyo_query_memory_size + len +
            sizeof(*tomoyo_query_entry) >= tomoyo_quota_for_query) {
                quota_exceeded = true;
        } else {
                tomoyo_query_memory_size += len + sizeof(*tomoyo_query_entry);
                tomoyo_query_entry->serial = tomoyo_serial++;
        }
        spin_unlock(&tomoyo_query_list_lock);
        if (quota_exceeded)
                goto out;
        pos = snprintf(tomoyo_query_entry->query, len - 1, "Q%u-%hu\n%s",
                       tomoyo_query_entry->serial, r->retry, header);
        kfree(header);
        header = NULL;
        va_start(args, fmt);
        vsnprintf(tomoyo_query_entry->query + pos, len - 1 - pos, fmt, args);
        tomoyo_query_entry->query_len = strlen(tomoyo_query_entry->query) + 1;
        va_end(args);
        spin_lock(&tomoyo_query_list_lock);
        list_add_tail(&tomoyo_query_entry->list, &tomoyo_query_list);
        spin_unlock(&tomoyo_query_list_lock);
        /* Give 10 seconds for supervisor's opinion. */
        for (tomoyo_query_entry->timer = 0;
             atomic_read(&tomoyo_query_observers) && tomoyo_query_entry->timer < 100;
             tomoyo_query_entry->timer++) {
                wake_up(&tomoyo_query_wait);
                set_current_state(TASK_INTERRUPTIBLE);
                schedule_timeout(HZ / 10);
                if (tomoyo_query_entry->answer)
                        break;
        }
        spin_lock(&tomoyo_query_list_lock);
        list_del(&tomoyo_query_entry->list);
        tomoyo_query_memory_size -= len + sizeof(*tomoyo_query_entry);
        spin_unlock(&tomoyo_query_list_lock);
        switch (tomoyo_query_entry->answer) {
        case 3: /* Asked to retry by administrator. */
                error = TOMOYO_RETRY_REQUEST;
                r->retry++;
                break;
        case 1:
                /* Granted by administrator. */
                error = 0;
                break;
        case 0:
                /* Timed out. */
                break;
        default:
                /* Rejected by administrator. */
                break;
        }
 out:
        if (tomoyo_query_entry)
                kfree(tomoyo_query_entry->query);
        kfree(tomoyo_query_entry);
        kfree(header);
        return error;
}

/**
 * tomoyo_poll_query - poll() for /sys/kernel/security/tomoyo/query.
 *
 * @file: Pointer to "struct file".
 * @wait: Pointer to "poll_table".
 *
 * Returns POLLIN | POLLRDNORM when ready to read, 0 otherwise.
 *
 * Waits for access requests which violated policy in enforcing mode.
 */
static int tomoyo_poll_query(struct file *file, poll_table *wait)
{
        struct list_head *tmp;
        bool found = false;
        u8 i;
        for (i = 0; i < 2; i++) {
                spin_lock(&tomoyo_query_list_lock);
                list_for_each(tmp, &tomoyo_query_list) {
                        struct tomoyo_query_entry *ptr
                                = list_entry(tmp, struct tomoyo_query_entry,
                                             list);
                        if (ptr->answer)
                                continue;
                        found = true;
                        break;
                }
                spin_unlock(&tomoyo_query_list_lock);
                if (found)
                        return POLLIN | POLLRDNORM;
                if (i)
                        break;
                poll_wait(file, &tomoyo_query_wait, wait);
        }
        return 0;
}

/**
 * tomoyo_read_query - Read access requests which violated policy in enforcing mode.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns 0.
 */
static int tomoyo_read_query(struct tomoyo_io_buffer *head)
{
        struct list_head *tmp;
        int pos = 0;
        int len = 0;
        char *buf;
        if (head->read_avail)
                return 0;
        if (head->read_buf) {
                kfree(head->read_buf);
                head->read_buf = NULL;
                head->readbuf_size = 0;
        }
        spin_lock(&tomoyo_query_list_lock);
        list_for_each(tmp, &tomoyo_query_list) {
                struct tomoyo_query_entry *ptr
                        = list_entry(tmp, struct tomoyo_query_entry, list);
                if (ptr->answer)
                        continue;
                if (pos++ != head->read_step)
                        continue;
                len = ptr->query_len;
                break;
        }
        spin_unlock(&tomoyo_query_list_lock);
        if (!len) {
                head->read_step = 0;
                return 0;
        }
        buf = kzalloc(len, GFP_NOFS);
        if (!buf)
                return 0;
        pos = 0;
        spin_lock(&tomoyo_query_list_lock);
        list_for_each(tmp, &tomoyo_query_list) {
                struct tomoyo_query_entry *ptr
                        = list_entry(tmp, struct tomoyo_query_entry, list);
                if (ptr->answer)
                        continue;
                if (pos++ != head->read_step)
                        continue;
                /*
                 * Some query can be skipped because tomoyo_query_list
                 * can change, but I don't care.
                 */
                if (len == ptr->query_len)
                        memmove(buf, ptr->query, len);
                break;
        }
        spin_unlock(&tomoyo_query_list_lock);
        if (buf[0]) {
                head->read_avail = len;
                head->readbuf_size = head->read_avail;
                head->read_buf = buf;
                head->read_step++;
        } else {
                kfree(buf);
        }
        return 0;
}

/**
 * tomoyo_write_answer - Write the supervisor's decision.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns 0 on success, -EINVAL otherwise.
 */
static int tomoyo_write_answer(struct tomoyo_io_buffer *head)
{
        char *data = head->write_buf;
        struct list_head *tmp;
        unsigned int serial;
        unsigned int answer;
        spin_lock(&tomoyo_query_list_lock);
        list_for_each(tmp, &tomoyo_query_list) {
                struct tomoyo_query_entry *ptr
                        = list_entry(tmp, struct tomoyo_query_entry, list);
                ptr->timer = 0;
        }
        spin_unlock(&tomoyo_query_list_lock);
        if (sscanf(data, "A%u=%u", &serial, &answer) != 2)
                return -EINVAL;
        spin_lock(&tomoyo_query_list_lock);
        list_for_each(tmp, &tomoyo_query_list) {
                struct tomoyo_query_entry *ptr
                        = list_entry(tmp, struct tomoyo_query_entry, list);
                if (ptr->serial != serial)
                        continue;
                if (!ptr->answer)
                        ptr->answer = answer;
                break;
        }
        spin_unlock(&tomoyo_query_list_lock);
        return 0;
}

/**
 * tomoyo_read_version: Get version.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns version information.
 */
static int tomoyo_read_version(struct tomoyo_io_buffer *head)
{
        if (!head->read_eof) {
                tomoyo_io_printf(head, "2.2.0");
                head->read_eof = true;
        }
        return 0;
}

/**
 * tomoyo_read_self_domain - Get the current process's domainname.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns the current process's domainname.
 */
static int tomoyo_read_self_domain(struct tomoyo_io_buffer *head)
{
        if (!head->read_eof) {
                /*
                 * tomoyo_domain()->domainname != NULL
                 * because every process belongs to a domain and
                 * the domain's name cannot be NULL.
                 */
                tomoyo_io_printf(head, "%s", tomoyo_domain()->domainname->name);
                head->read_eof = true;
        }
        return 0;
}

/**
 * tomoyo_open_control - open() for /sys/kernel/security/tomoyo/ interface.
 *
 * @type: Type of interface.
 * @file: Pointer to "struct file".
 *
 * Associates policy handler and returns 0 on success, -ENOMEM otherwise.
 *
 * Caller acquires tomoyo_read_lock().
 */
int tomoyo_open_control(const u8 type, struct file *file)
{
        struct tomoyo_io_buffer *head = kzalloc(sizeof(*head), GFP_NOFS);

        if (!head)
                return -ENOMEM;
        mutex_init(&head->io_sem);
        head->type = type;
        switch (type) {
        case TOMOYO_DOMAINPOLICY:
                /* /sys/kernel/security/tomoyo/domain_policy */
                head->write = tomoyo_write_domain_policy;
                head->read = tomoyo_read_domain_policy;
                break;
        case TOMOYO_EXCEPTIONPOLICY:
                /* /sys/kernel/security/tomoyo/exception_policy */
                head->write = tomoyo_write_exception_policy;
                head->read = tomoyo_read_exception_policy;
                break;
        case TOMOYO_SELFDOMAIN:
                /* /sys/kernel/security/tomoyo/self_domain */
                head->read = tomoyo_read_self_domain;
                break;
        case TOMOYO_DOMAIN_STATUS:
                /* /sys/kernel/security/tomoyo/.domain_status */
                head->write = tomoyo_write_domain_profile;
                head->read = tomoyo_read_domain_profile;
                break;
        case TOMOYO_PROCESS_STATUS:
                /* /sys/kernel/security/tomoyo/.process_status */
                head->write = tomoyo_write_pid;
                head->read = tomoyo_read_pid;
                break;
        case TOMOYO_VERSION:
                /* /sys/kernel/security/tomoyo/version */
                head->read = tomoyo_read_version;
                head->readbuf_size = 128;
                break;
        case TOMOYO_MEMINFO:
                /* /sys/kernel/security/tomoyo/meminfo */
                head->write = tomoyo_write_memory_quota;
                head->read = tomoyo_read_memory_counter;
                head->readbuf_size = 512;
                break;
        case TOMOYO_PROFILE:
                /* /sys/kernel/security/tomoyo/profile */
                head->write = tomoyo_write_profile;
                head->read = tomoyo_read_profile;
                break;
        case TOMOYO_QUERY: /* /sys/kernel/security/tomoyo/query */
                head->poll = tomoyo_poll_query;
                head->write = tomoyo_write_answer;
                head->read = tomoyo_read_query;
                break;
        case TOMOYO_MANAGER:
                /* /sys/kernel/security/tomoyo/manager */
                head->write = tomoyo_write_manager_policy;
                head->read = tomoyo_read_manager_policy;
                break;
        }
        if (!(file->f_mode & FMODE_READ)) {
                /*
                 * No need to allocate read_buf since it is not opened
                 * for reading.
                 */
                head->read = NULL;
                head->poll = NULL;
        } else if (!head->poll) {
                /* Don't allocate read_buf for poll() access. */
                if (!head->readbuf_size)
                        head->readbuf_size = 4096 * 2;
                head->read_buf = kzalloc(head->readbuf_size, GFP_NOFS);
                if (!head->read_buf) {
                        kfree(head);
                        return -ENOMEM;
                }
        }
        if (!(file->f_mode & FMODE_WRITE)) {
                /*
                 * No need to allocate write_buf since it is not opened
                 * for writing.
                 */
                head->write = NULL;
        } else if (head->write) {
                head->writebuf_size = 4096 * 2;
                head->write_buf = kzalloc(head->writebuf_size, GFP_NOFS);
                if (!head->write_buf) {
                        kfree(head->read_buf);
                        kfree(head);
                        return -ENOMEM;
                }
        }
        if (type != TOMOYO_QUERY)
                head->reader_idx = tomoyo_read_lock();
        file->private_data = head;
        /*
         * Call the handler now if the file is
         * /sys/kernel/security/tomoyo/self_domain
         * so that the user can use
         * cat < /sys/kernel/security/tomoyo/self_domain"
         * to know the current process's domainname.
         */
        if (type == TOMOYO_SELFDOMAIN)
                tomoyo_read_control(file, NULL, 0);
        /*
         * If the file is /sys/kernel/security/tomoyo/query , increment the
         * observer counter.
         * The obserber counter is used by tomoyo_supervisor() to see if
         * there is some process monitoring /sys/kernel/security/tomoyo/query.
         */
        else if (type == TOMOYO_QUERY)
                atomic_inc(&tomoyo_query_observers);
        return 0;
}

/**
 * tomoyo_poll_control - poll() for /sys/kernel/security/tomoyo/ interface.
 *
 * @file: Pointer to "struct file".
 * @wait: Pointer to "poll_table".
 *
 * Waits for read readiness.
 * /sys/kernel/security/tomoyo/query is handled by /usr/sbin/tomoyo-queryd .
 */
int tomoyo_poll_control(struct file *file, poll_table *wait)
{
        struct tomoyo_io_buffer *head = file->private_data;
        if (!head->poll)
                return -ENOSYS;
        return head->poll(file, wait);
}

/**
 * tomoyo_read_control - read() for /sys/kernel/security/tomoyo/ interface.
 *
 * @file:       Pointer to "struct file".
 * @buffer:     Poiner to buffer to write to.
 * @buffer_len: Size of @buffer.
 *
 * Returns bytes read on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
int tomoyo_read_control(struct file *file, char __user *buffer,
                        const int buffer_len)
{
        int len = 0;
        struct tomoyo_io_buffer *head = file->private_data;
        char *cp;

        if (!head->read)
                return -ENOSYS;
        if (mutex_lock_interruptible(&head->io_sem))
                return -EINTR;
        /* Call the policy handler. */
        len = head->read(head);
        if (len < 0)
                goto out;
        /* Write to buffer. */
        len = head->read_avail;
        if (len > buffer_len)
                len = buffer_len;
        if (!len)
                goto out;
        /* head->read_buf changes by some functions. */
        cp = head->read_buf;
        if (copy_to_user(buffer, cp, len)) {
                len = -EFAULT;
                goto out;
        }
        head->read_avail -= len;
        memmove(cp, cp + len, head->read_avail);
 out:
        mutex_unlock(&head->io_sem);
        return len;
}

/**
 * tomoyo_write_control - write() for /sys/kernel/security/tomoyo/ interface.
 *
 * @file:       Pointer to "struct file".
 * @buffer:     Pointer to buffer to read from.
 * @buffer_len: Size of @buffer.
 *
 * Returns @buffer_len on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
int tomoyo_write_control(struct file *file, const char __user *buffer,
                         const int buffer_len)
{
        struct tomoyo_io_buffer *head = file->private_data;
        int error = buffer_len;
        int avail_len = buffer_len;
        char *cp0 = head->write_buf;

        if (!head->write)
                return -ENOSYS;
        if (!access_ok(VERIFY_READ, buffer, buffer_len))
                return -EFAULT;
        /* Don't allow updating policies by non manager programs. */
        if (head->write != tomoyo_write_pid &&
            head->write != tomoyo_write_domain_policy &&
            !tomoyo_is_policy_manager())
                return -EPERM;
        if (mutex_lock_interruptible(&head->io_sem))
                return -EINTR;
        /* Read a line and dispatch it to the policy handler. */
        while (avail_len > 0) {
                char c;
                if (head->write_avail >= head->writebuf_size - 1) {
                        error = -ENOMEM;
                        break;
                } else if (get_user(c, buffer)) {
                        error = -EFAULT;
                        break;
                }
                buffer++;
                avail_len--;
                cp0[head->write_avail++] = c;
                if (c != '\n')
                        continue;
                cp0[head->write_avail - 1] = '\0';
                head->write_avail = 0;
                tomoyo_normalize_line(cp0);
                head->write(head);
        }
        mutex_unlock(&head->io_sem);
        return error;
}

/**
 * tomoyo_close_control - close() for /sys/kernel/security/tomoyo/ interface.
 *
 * @file: Pointer to "struct file".
 *
 * Releases memory and returns 0.
 *
 * Caller looses tomoyo_read_lock().
 */
int tomoyo_close_control(struct file *file)
{
        struct tomoyo_io_buffer *head = file->private_data;
        const bool is_write = !!head->write_buf;

        /*
         * If the file is /sys/kernel/security/tomoyo/query , decrement the
         * observer counter.
         */
        if (head->type == TOMOYO_QUERY)
                atomic_dec(&tomoyo_query_observers);
        else
                tomoyo_read_unlock(head->reader_idx);
        /* Release memory used for policy I/O. */
        kfree(head->read_buf);
        head->read_buf = NULL;
        kfree(head->write_buf);
        head->write_buf = NULL;
        kfree(head);
        head = NULL;
        file->private_data = NULL;
        if (is_write)
                tomoyo_run_gc();
        return 0;
}

/**
 * tomoyo_check_profile - Check all profiles currently assigned to domains are defined.
 */
void tomoyo_check_profile(void)
{
        struct tomoyo_domain_info *domain;
        const int idx = tomoyo_read_lock();
        tomoyo_policy_loaded = true;
        /* Check all profiles currently assigned to domains are defined. */
        list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
                const u8 profile = domain->profile;
                if (tomoyo_profile_ptr[profile])
                        continue;
                panic("Profile %u (used by '%s') not defined.\n",
                      profile, domain->domainname->name);
        }
        tomoyo_read_unlock(idx);
        printk(KERN_INFO "TOMOYO: 2.2.0   2009/04/01\n");
        printk(KERN_INFO "Mandatory Access Control activated.\n");
}