/*
 * 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 "common.h"

static struct tomoyo_profile tomoyo_default_profile = {
        .learning = &tomoyo_default_profile.preference,
        .permissive = &tomoyo_default_profile.preference,
        .enforcing = &tomoyo_default_profile.preference,
        .preference.enforcing_verbose = true,
        .preference.learning_max_entry = 2048,
        .preference.learning_verbose = false,
        .preference.permissive_verbose = true
};

/* Profile version. Currently only 20090903 is defined. */
static unsigned int tomoyo_profile_version;

/* Profile table. Memory is allocated as needed. */
static struct tomoyo_profile *tomoyo_profile_ptr[TOMOYO_MAX_PROFILES];

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

/* String table for /sys/kernel/security/tomoyo/profile */
static const char *tomoyo_mac_keywords[TOMOYO_MAX_MAC_INDEX
                                       + TOMOYO_MAX_MAC_CATEGORY_INDEX] = {
        [TOMOYO_MAC_FILE_EXECUTE]    = "file::execute",
        [TOMOYO_MAC_FILE_OPEN]       = "file::open",
        [TOMOYO_MAC_FILE_CREATE]     = "file::create",
        [TOMOYO_MAC_FILE_UNLINK]     = "file::unlink",
        [TOMOYO_MAC_FILE_MKDIR]      = "file::mkdir",
        [TOMOYO_MAC_FILE_RMDIR]      = "file::rmdir",
        [TOMOYO_MAC_FILE_MKFIFO]     = "file::mkfifo",
        [TOMOYO_MAC_FILE_MKSOCK]     = "file::mksock",
        [TOMOYO_MAC_FILE_TRUNCATE]   = "file::truncate",
        [TOMOYO_MAC_FILE_SYMLINK]    = "file::symlink",
        [TOMOYO_MAC_FILE_REWRITE]    = "file::rewrite",
        [TOMOYO_MAC_FILE_MKBLOCK]    = "file::mkblock",
        [TOMOYO_MAC_FILE_MKCHAR]     = "file::mkchar",
        [TOMOYO_MAC_FILE_LINK]       = "file::link",
        [TOMOYO_MAC_FILE_RENAME]     = "file::rename",
        [TOMOYO_MAC_FILE_CHMOD]      = "file::chmod",
        [TOMOYO_MAC_FILE_CHOWN]      = "file::chown",
        [TOMOYO_MAC_FILE_CHGRP]      = "file::chgrp",
        [TOMOYO_MAC_FILE_IOCTL]      = "file::ioctl",
        [TOMOYO_MAC_FILE_CHROOT]     = "file::chroot",
        [TOMOYO_MAC_FILE_MOUNT]      = "file::mount",
        [TOMOYO_MAC_FILE_UMOUNT]     = "file::umount",
        [TOMOYO_MAC_FILE_PIVOT_ROOT] = "file::pivot_root",
        [TOMOYO_MAX_MAC_INDEX + TOMOYO_MAC_CATEGORY_FILE] = "file",
};

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

/* Utility functions. */

/**
 * tomoyo_yesno - Return "yes" or "no".
 *
 * @value: Bool value.
 */
static const char *tomoyo_yesno(const unsigned int value)
{
        return value ? "yes" : "no";
}

static void tomoyo_addprintf(char *buffer, int len, const char *fmt, ...)
{
        va_list args;
        const int pos = strlen(buffer);
        va_start(args, fmt);
        vsnprintf(buffer + pos, len - pos - 1, fmt, args);
        va_end(args);
}

/**
 * tomoyo_flush - Flush queued string to userspace's buffer.
 *
 * @head:   Pointer to "struct tomoyo_io_buffer".
 *
 * Returns true if all data was flushed, false otherwise.
 */
static bool tomoyo_flush(struct tomoyo_io_buffer *head)
{
        while (head->r.w_pos) {
                const char *w = head->r.w[0];
                int len = strlen(w);
                if (len) {
                        if (len > head->read_user_buf_avail)
                                len = head->read_user_buf_avail;
                        if (!len)
                                return false;
                        if (copy_to_user(head->read_user_buf, w, len))
                                return false;
                        head->read_user_buf_avail -= len;
                        head->read_user_buf += len;
                        w += len;
                }
                head->r.w[0] = w;
                if (*w)
                        return false;
                /* Add '\0' for query. */
                if (head->poll) {
                        if (!head->read_user_buf_avail ||
                            copy_to_user(head->read_user_buf, "", 1))
                                return false;
                        head->read_user_buf_avail--;
                        head->read_user_buf++;
                }
                head->r.w_pos--;
                for (len = 0; len < head->r.w_pos; len++)
                        head->r.w[len] = head->r.w[len + 1];
        }
        head->r.avail = 0;
        return true;
}

/**
 * tomoyo_set_string - Queue string to "struct tomoyo_io_buffer" structure.
 *
 * @head:   Pointer to "struct tomoyo_io_buffer".
 * @string: String to print.
 *
 * Note that @string has to be kept valid until @head is kfree()d.
 * This means that char[] allocated on stack memory cannot be passed to
 * this function. Use tomoyo_io_printf() for char[] allocated on stack memory.
 */
static void tomoyo_set_string(struct tomoyo_io_buffer *head, const char *string)
{
        if (head->r.w_pos < TOMOYO_MAX_IO_READ_QUEUE) {
                head->r.w[head->r.w_pos++] = string;
                tomoyo_flush(head);
        } else
                WARN_ON(1);
}

/**
 * tomoyo_io_printf - printf() to "struct tomoyo_io_buffer" structure.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 * @fmt:  The printf()'s format string, followed by parameters.
 */
void tomoyo_io_printf(struct tomoyo_io_buffer *head, const char *fmt, ...)
{
        va_list args;
        int len;
        int pos = head->r.avail;
        int size = head->readbuf_size - pos;
        if (size <= 0)
                return;
        va_start(args, fmt);
        len = vsnprintf(head->read_buf + pos, size, fmt, args) + 1;
        va_end(args);
        if (pos + len >= head->readbuf_size) {
                WARN_ON(1);
                return;
        }
        head->r.avail += len;
        tomoyo_set_string(head, head->read_buf + pos);
}

static void tomoyo_set_space(struct tomoyo_io_buffer *head)
{
        tomoyo_set_string(head, " ");
}

static bool tomoyo_set_lf(struct tomoyo_io_buffer *head)
{
        tomoyo_set_string(head, "\n");
        return !head->r.w_pos;
}

/**
 * tomoyo_print_name_union - Print a tomoyo_name_union.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 * @ptr:  Pointer to "struct tomoyo_name_union".
 */
static void tomoyo_print_name_union(struct tomoyo_io_buffer *head,
                                    const struct tomoyo_name_union *ptr)
{
        tomoyo_set_space(head);
        if (ptr->is_group) {
                tomoyo_set_string(head, "@");
                tomoyo_set_string(head, ptr->group->group_name->name);
        } else {
                tomoyo_set_string(head, 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".
 */
static void tomoyo_print_number_union(struct tomoyo_io_buffer *head,
                                      const struct tomoyo_number_union *ptr)
{
        tomoyo_set_space(head);
        if (ptr->is_group) {
                tomoyo_set_string(head, "@");
                tomoyo_set_string(head, ptr->group->group_name->name);
        } else {
                int i;
                unsigned long min = ptr->values[0];
                const unsigned long max = ptr->values[1];
                u8 min_type = ptr->min_type;
                const u8 max_type = ptr->max_type;
                char buffer[128];
                buffer[0] = '\0';
                for (i = 0; i < 2; i++) {
                        switch (min_type) {
                        case TOMOYO_VALUE_TYPE_HEXADECIMAL:
                                tomoyo_addprintf(buffer, sizeof(buffer),
                                                 "0x%lX", min);
                                break;
                        case TOMOYO_VALUE_TYPE_OCTAL:
                                tomoyo_addprintf(buffer, sizeof(buffer),
                                                 "0%lo", min);
                                break;
                        default:
                                tomoyo_addprintf(buffer, sizeof(buffer),
                                                 "%lu", min);
                                break;
                        }
                        if (min == max && min_type == max_type)
                                break;
                        tomoyo_addprintf(buffer, sizeof(buffer), "-");
                        min_type = max_type;
                        min = max;
                }
                tomoyo_io_printf(head, "%s", buffer);
        }
}

/**
 * tomoyo_assign_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_assign_profile(const unsigned int profile)
{
        struct tomoyo_profile *ptr;
        struct tomoyo_profile *entry;
        if (profile >= TOMOYO_MAX_PROFILES)
                return NULL;
        ptr = tomoyo_profile_ptr[profile];
        if (ptr)
                return ptr;
        entry = kzalloc(sizeof(*entry), GFP_NOFS);
        if (mutex_lock_interruptible(&tomoyo_policy_lock))
                goto out;
        ptr = tomoyo_profile_ptr[profile];
        if (!ptr && tomoyo_memory_ok(entry)) {
                ptr = entry;
                ptr->learning = &tomoyo_default_profile.preference;
                ptr->permissive = &tomoyo_default_profile.preference;
                ptr->enforcing = &tomoyo_default_profile.preference;
                ptr->default_config = TOMOYO_CONFIG_DISABLED;
                memset(ptr->config, TOMOYO_CONFIG_USE_DEFAULT,
                       sizeof(ptr->config));
                mb(); /* Avoid out-of-order execution. */
                tomoyo_profile_ptr[profile] = ptr;
                entry = NULL;
        }
        mutex_unlock(&tomoyo_policy_lock);
 out:
        kfree(entry);
        return ptr;
}

/**
 * tomoyo_profile - Find a profile.
 *
 * @profile: Profile number to find.
 *
 * Returns pointer to "struct tomoyo_profile".
 */
struct tomoyo_profile *tomoyo_profile(const u8 profile)
{
        struct tomoyo_profile *ptr = tomoyo_profile_ptr[profile];
        if (!tomoyo_policy_loaded)
                return &tomoyo_default_profile;
        BUG_ON(!ptr);
        return ptr;
}

static s8 tomoyo_find_yesno(const char *string, const char *find)
{
        const char *cp = strstr(string, find);
        if (cp) {
                cp += strlen(find);
                if (!strncmp(cp, "=yes", 4))
                        return 1;
                else if (!strncmp(cp, "=no", 3))
                        return 0;
        }
        return -1;
}

static void tomoyo_set_bool(bool *b, const char *string, const char *find)
{
        switch (tomoyo_find_yesno(string, find)) {
        case 1:
                *b = true;
                break;
        case 0:
                *b = false;
                break;
        }
}

static void tomoyo_set_uint(unsigned int *i, const char *string,
                            const char *find)
{
        const char *cp = strstr(string, find);
        if (cp)
                sscanf(cp + strlen(find), "=%u", i);
}

static void tomoyo_set_pref(const char *name, const char *value,
                            const bool use_default,
                            struct tomoyo_profile *profile)
{
        struct tomoyo_preference **pref;
        bool *verbose;
        if (!strcmp(name, "enforcing")) {
                if (use_default) {
                        pref = &profile->enforcing;
                        goto set_default;
                }
                profile->enforcing = &profile->preference;
                verbose = &profile->preference.enforcing_verbose;
                goto set_verbose;
        }
        if (!strcmp(name, "permissive")) {
                if (use_default) {
                        pref = &profile->permissive;
                        goto set_default;
                }
                profile->permissive = &profile->preference;
                verbose = &profile->preference.permissive_verbose;
                goto set_verbose;
        }
        if (!strcmp(name, "learning")) {
                if (use_default) {
                        pref = &profile->learning;
                        goto set_default;
                }
                profile->learning = &profile->preference;
                tomoyo_set_uint(&profile->preference.learning_max_entry, value,
                             "max_entry");
                verbose = &profile->preference.learning_verbose;
                goto set_verbose;
        }
        return;
 set_default:
        *pref = &tomoyo_default_profile.preference;
        return;
 set_verbose:
        tomoyo_set_bool(verbose, value, "verbose");
}

static int tomoyo_set_mode(char *name, const char *value,
                           const bool use_default,
                           struct tomoyo_profile *profile)
{
        u8 i;
        u8 config;
        if (!strcmp(name, "CONFIG")) {
                i = TOMOYO_MAX_MAC_INDEX + TOMOYO_MAX_MAC_CATEGORY_INDEX;
                config = profile->default_config;
        } else if (tomoyo_str_starts(&name, "CONFIG::")) {
                config = 0;
                for (i = 0; i < TOMOYO_MAX_MAC_INDEX
                             + TOMOYO_MAX_MAC_CATEGORY_INDEX; i++) {
                        if (strcmp(name, tomoyo_mac_keywords[i]))
                                continue;
                        config = profile->config[i];
                        break;
                }
                if (i == TOMOYO_MAX_MAC_INDEX + TOMOYO_MAX_MAC_CATEGORY_INDEX)
                        return -EINVAL;
        } else {
                return -EINVAL;
        }
        if (use_default) {
                config = TOMOYO_CONFIG_USE_DEFAULT;
        } else {
                u8 mode;
                for (mode = 0; mode < 4; mode++)
                        if (strstr(value, tomoyo_mode[mode]))
                                /*
                                 * Update lower 3 bits in order to distinguish
                                 * 'config' from 'TOMOYO_CONFIG_USE_DEAFULT'.
                                 */
                                config = (config & ~7) | mode;
        }
        if (i < TOMOYO_MAX_MAC_INDEX + TOMOYO_MAX_MAC_CATEGORY_INDEX)
                profile->config[i] = config;
        else if (config != TOMOYO_CONFIG_USE_DEFAULT)
                profile->default_config = config;
        return 0;
}

/**
 * tomoyo_write_profile - Write 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;
        bool use_default = false;
        char *cp;
        struct tomoyo_profile *profile;
        if (sscanf(data, "PROFILE_VERSION=%u", &tomoyo_profile_version) == 1)
                return 0;
        i = simple_strtoul(data, &cp, 10);
        if (data == cp) {
                profile = &tomoyo_default_profile;
        } else {
                if (*cp != '-')
                        return -EINVAL;
                data = cp + 1;
                profile = tomoyo_assign_profile(i);
                if (!profile)
                        return -EINVAL;
        }
        cp = strchr(data, '=');
        if (!cp)
                return -EINVAL;
        *cp++ = '\0';
        if (profile != &tomoyo_default_profile)
                use_default = strstr(cp, "use_default") != NULL;
        if (tomoyo_str_starts(&data, "PREFERENCE::")) {
                tomoyo_set_pref(data, cp, use_default, profile);
                return 0;
        }
        if (profile == &tomoyo_default_profile)
                return -EINVAL;
        if (!strcmp(data, "COMMENT")) {
                static DEFINE_SPINLOCK(lock);
                const struct tomoyo_path_info *new_comment
                        = tomoyo_get_name(cp);
                const struct tomoyo_path_info *old_comment;
                if (!new_comment)
                        return -ENOMEM;
                spin_lock(&lock);
                old_comment = profile->comment;
                profile->comment = new_comment;
                spin_unlock(&lock);
                tomoyo_put_name(old_comment);
                return 0;
        }
        return tomoyo_set_mode(data, cp, use_default, profile);
}

static void tomoyo_print_preference(struct tomoyo_io_buffer *head,
                                    const int idx)
{
        struct tomoyo_preference *pref = &tomoyo_default_profile.preference;
        const struct tomoyo_profile *profile = idx >= 0 ?
                tomoyo_profile_ptr[idx] : NULL;
        char buffer[16] = "";
        if (profile) {
                buffer[sizeof(buffer) - 1] = '\0';
                snprintf(buffer, sizeof(buffer) - 1, "%u-", idx);
        }
        if (profile) {
                pref = profile->learning;
                if (pref == &tomoyo_default_profile.preference)
                        goto skip1;
        }
        tomoyo_io_printf(head, "%sPREFERENCE::%s={ "
                         "verbose=%s max_entry=%u }\n",
                         buffer, "learning",
                         tomoyo_yesno(pref->learning_verbose),
                         pref->learning_max_entry);
 skip1:
        if (profile) {
                pref = profile->permissive;
                if (pref == &tomoyo_default_profile.preference)
                        goto skip2;
        }
        tomoyo_io_printf(head, "%sPREFERENCE::%s={ verbose=%s }\n",
                         buffer, "permissive",
                         tomoyo_yesno(pref->permissive_verbose));
 skip2:
        if (profile) {
                pref = profile->enforcing;
                if (pref == &tomoyo_default_profile.preference)
                        return;
        }
        tomoyo_io_printf(head, "%sPREFERENCE::%s={ verbose=%s }\n",
                         buffer, "enforcing",
                         tomoyo_yesno(pref->enforcing_verbose));
}

static void tomoyo_print_config(struct tomoyo_io_buffer *head, const u8 config)
{
        tomoyo_io_printf(head, "={ mode=%s }\n", tomoyo_mode[config & 3]);
}

/**
 * tomoyo_read_profile - Read profile table.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 */
static void tomoyo_read_profile(struct tomoyo_io_buffer *head)
{
        u8 index;
        const struct tomoyo_profile *profile;
 next:
        index = head->r.index;
        profile = tomoyo_profile_ptr[index];
        switch (head->r.step) {
        case 0:
                tomoyo_io_printf(head, "PROFILE_VERSION=%s\n", "20090903");
                tomoyo_print_preference(head, -1);
                head->r.step++;
                break;
        case 1:
                for ( ; head->r.index < TOMOYO_MAX_PROFILES;
                      head->r.index++)
                        if (tomoyo_profile_ptr[head->r.index])
                                break;
                if (head->r.index == TOMOYO_MAX_PROFILES)
                        return;
                head->r.step++;
                break;
        case 2:
                {
                        const struct tomoyo_path_info *comment =
                                profile->comment;
                        tomoyo_io_printf(head, "%u-COMMENT=", index);
                        tomoyo_set_string(head, comment ? comment->name : "");
                        tomoyo_set_lf(head);
                        head->r.step++;
                }
                break;
        case 3:
                {
                        tomoyo_io_printf(head, "%u-%s", index, "CONFIG");
                        tomoyo_print_config(head, profile->default_config);
                        head->r.bit = 0;
                        head->r.step++;
                }
                break;
        case 4:
                for ( ; head->r.bit < TOMOYO_MAX_MAC_INDEX
                              + TOMOYO_MAX_MAC_CATEGORY_INDEX; head->r.bit++) {
                        const u8 i = head->r.bit;
                        const u8 config = profile->config[i];
                        if (config == TOMOYO_CONFIG_USE_DEFAULT)
                                continue;
                        tomoyo_io_printf(head, "%u-%s%s", index, "CONFIG::",
                                         tomoyo_mac_keywords[i]);
                        tomoyo_print_config(head, config);
                        head->r.bit++;
                        break;
                }
                if (head->r.bit == TOMOYO_MAX_MAC_INDEX
                    + TOMOYO_MAX_MAC_CATEGORY_INDEX) {
                        tomoyo_print_preference(head, index);
                        head->r.index++;
                        head->r.step = 1;
                }
                break;
        }
        if (tomoyo_flush(head))
                goto next;
}

static bool tomoyo_same_manager(const struct tomoyo_acl_head *a,
                                const struct tomoyo_acl_head *b)
{
        return container_of(a, struct tomoyo_manager, head)->manager ==
                container_of(b, struct tomoyo_manager, head)->manager;
}

/**
 * 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_manager e = { };
        int error;

        if (tomoyo_domain_def(manager)) {
                if (!tomoyo_correct_domain(manager))
                        return -EINVAL;
                e.is_domain = true;
        } else {
                if (!tomoyo_correct_path(manager))
                        return -EINVAL;
        }
        e.manager = tomoyo_get_name(manager);
        if (!e.manager)
                return -ENOMEM;
        error = tomoyo_update_policy(&e.head, sizeof(e), is_delete,
                                     &tomoyo_policy_list[TOMOYO_ID_MANAGER],
                                     tomoyo_same_manager);
        tomoyo_put_name(e.manager);
        return error;
}

/**
 * tomoyo_write_manager - 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(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 - Read manager policy.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Caller holds tomoyo_read_lock().
 */
static void tomoyo_read_manager(struct tomoyo_io_buffer *head)
{
        if (head->r.eof)
                return;
        list_for_each_cookie(head->r.acl,
                             &tomoyo_policy_list[TOMOYO_ID_MANAGER]) {
                struct tomoyo_manager *ptr =
                        list_entry(head->r.acl, typeof(*ptr), head.list);
                if (ptr->head.is_deleted)
                        continue;
                if (!tomoyo_flush(head))
                        return;
                tomoyo_set_string(head, ptr->manager->name);
                tomoyo_set_lf(head);
        }
        head->r.eof = true;
}

/**
 * tomoyo_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_manager(void)
{
        struct tomoyo_manager *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_list[TOMOYO_ID_MANAGER],
                                head.list) {
                if (!ptr->head.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_list[TOMOYO_ID_MANAGER],
                                head.list) {
                if (!ptr->head.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_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_select_one(struct tomoyo_io_buffer *head, const char *data)
{
        unsigned int pid;
        struct tomoyo_domain_info *domain = NULL;
        bool global_pid = false;

        if (!strcmp(data, "allow_execute")) {
                head->r.print_execute_only = true;
                return true;
        }
        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_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). */
        memset(&head->r, 0, sizeof(head->r));
        head->r.print_this_domain_only = true;
        if (domain)
                head->r.domain = &domain->list;
        else
                head->r.eof = 1;
        tomoyo_io_printf(head, "# select %s\n", data);
        if (domain && 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_domain2 - 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_domain2(char *data, struct tomoyo_domain_info *domain,
                                const bool is_delete)
{
        if (tomoyo_str_starts(&data, TOMOYO_KEYWORD_ALLOW_MOUNT))
                return tomoyo_write_mount(data, domain, is_delete);
        return tomoyo_write_file(data, domain, is_delete);
}

/**
 * tomoyo_write_domain - 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(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_select_one(head, data))
                return 0;
        /* Don't allow updating policies by non manager programs. */
        if (!tomoyo_manager())
                return -EPERM;
        if (tomoyo_domain_def(data)) {
                domain = NULL;
                if (is_delete)
                        tomoyo_delete_domain(data);
                else if (is_select)
                        domain = tomoyo_find_domain(data);
                else
                        domain = tomoyo_assign_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_domain2(data, domain, is_delete);
}

/**
 * tomoyo_fns - Find next set bit.
 *
 * @perm: 8 bits value.
 * @bit:  First bit to find.
 *
 * Returns next on-bit on success, 8 otherwise.
 */
static u8 tomoyo_fns(const u8 perm, u8 bit)
{
        for ( ; bit < 8; bit++)
                if (perm & (1 << bit))
                        break;
        return bit;
}

/**
 * tomoyo_print_entry - Print an ACL entry.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 * @acl:  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 *acl)
{
        const u8 acl_type = acl->type;
        u8 bit;

        if (acl->is_deleted)
                return true;
 next:
        bit = head->r.bit;
        if (!tomoyo_flush(head))
                return false;
        else if (acl_type == TOMOYO_TYPE_PATH_ACL) {
                struct tomoyo_path_acl *ptr =
                        container_of(acl, typeof(*ptr), head);
                const u16 perm = ptr->perm;
                for ( ; bit < TOMOYO_MAX_PATH_OPERATION; bit++) {
                        if (!(perm & (1 << bit)))
                                continue;
                        if (head->r.print_execute_only &&
                            bit != TOMOYO_TYPE_EXECUTE)
                                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;
                        break;
                }
                if (bit >= TOMOYO_MAX_PATH_OPERATION)
                        goto done;
                tomoyo_io_printf(head, "allow_%s", tomoyo_path_keyword[bit]);
                tomoyo_print_name_union(head, &ptr->name);
        } else if (head->r.print_execute_only) {
                return true;
        } else if (acl_type == TOMOYO_TYPE_PATH2_ACL) {
                struct tomoyo_path2_acl *ptr =
                        container_of(acl, typeof(*ptr), head);
                bit = tomoyo_fns(ptr->perm, bit);
                if (bit >= TOMOYO_MAX_PATH2_OPERATION)
                        goto done;
                tomoyo_io_printf(head, "allow_%s", tomoyo_path2_keyword[bit]);
                tomoyo_print_name_union(head, &ptr->name1);
                tomoyo_print_name_union(head, &ptr->name2);
        } else if (acl_type == TOMOYO_TYPE_PATH_NUMBER_ACL) {
                struct tomoyo_path_number_acl *ptr =
                        container_of(acl, typeof(*ptr), head);
                bit = tomoyo_fns(ptr->perm, bit);
                if (bit >= TOMOYO_MAX_PATH_NUMBER_OPERATION)
                        goto done;
                tomoyo_io_printf(head, "allow_%s",
                                 tomoyo_path_number_keyword[bit]);
                tomoyo_print_name_union(head, &ptr->name);
                tomoyo_print_number_union(head, &ptr->number);
        } else if (acl_type == TOMOYO_TYPE_MKDEV_ACL) {
                struct tomoyo_mkdev_acl *ptr =
                        container_of(acl, typeof(*ptr), head);
                bit = tomoyo_fns(ptr->perm, bit);
                if (bit >= TOMOYO_MAX_MKDEV_OPERATION)
                        goto done;
                tomoyo_io_printf(head, "allow_%s", tomoyo_mkdev_keyword[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);
        } else if (acl_type == TOMOYO_TYPE_MOUNT_ACL) {
                struct tomoyo_mount_acl *ptr =
                        container_of(acl, typeof(*ptr), head);
                tomoyo_io_printf(head, "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);
        }
        head->r.bit = bit + 1;
        tomoyo_io_printf(head, "\n");
        if (acl_type != TOMOYO_TYPE_MOUNT_ACL)
                goto next;

 done:
        head->r.bit = 0;
        return true;
}

/**
 * tomoyo_read_domain2 - Read domain policy.
 *
 * @head:   Pointer to "struct tomoyo_io_buffer".
 * @domain: Pointer to "struct tomoyo_domain_info".
 *
 * Caller holds tomoyo_read_lock().
 *
 * Returns true on success, false otherwise.
 */
static bool tomoyo_read_domain2(struct tomoyo_io_buffer *head,
                                struct tomoyo_domain_info *domain)
{
        list_for_each_cookie(head->r.acl, &domain->acl_info_list) {
                struct tomoyo_acl_info *ptr =
                        list_entry(head->r.acl, typeof(*ptr), list);
                if (!tomoyo_print_entry(head, ptr))
                        return false;
        }
        head->r.acl = NULL;
        return true;
}

/**
 * tomoyo_read_domain - Read domain policy.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Caller holds tomoyo_read_lock().
 */
static void tomoyo_read_domain(struct tomoyo_io_buffer *head)
{
        if (head->r.eof)
                return;
        list_for_each_cookie(head->r.domain, &tomoyo_domain_list) {
                struct tomoyo_domain_info *domain =
                        list_entry(head->r.domain, typeof(*domain), list);
                switch (head->r.step) {
                case 0:
                        if (domain->is_deleted &&
                            !head->r.print_this_domain_only)
                                continue;
                        /* Print domainname and flags. */
                        tomoyo_set_string(head, domain->domainname->name);
                        tomoyo_set_lf(head);
                        tomoyo_io_printf(head,
                                         TOMOYO_KEYWORD_USE_PROFILE "%u\n",
                                         domain->profile);
                        if (domain->quota_warned)
                                tomoyo_set_string(head, "quota_exceeded\n");
                        if (domain->transition_failed)
                                tomoyo_set_string(head, "transition_failed\n");
                        if (domain->ignore_global_allow_read)
                                tomoyo_set_string(head,
                                       TOMOYO_KEYWORD_IGNORE_GLOBAL_ALLOW_READ
                                                  "\n");
                        head->r.step++;
                        tomoyo_set_lf(head);
                        /* fall through */
                case 1:
                        if (!tomoyo_read_domain2(head, domain))
                                return;
                        head->r.step++;
                        if (!tomoyo_set_lf(head))
                                return;
                        /* fall through */
                case 2:
                        head->r.step = 0;
                        if (head->r.print_this_domain_only)
                                goto done;
                }
        }
 done:
        head->r.eof = true;
}

/**
 * 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 void tomoyo_read_domain_profile(struct tomoyo_io_buffer *head)
{
        if (head->r.eof)
                return;
        list_for_each_cookie(head->r.domain, &tomoyo_domain_list) {
                struct tomoyo_domain_info *domain =
                        list_entry(head->r.domain, typeof(*domain), list);
                if (domain->is_deleted)
                        continue;
                if (!tomoyo_flush(head))
                        return;
                tomoyo_io_printf(head, "%u ", domain->profile);
                tomoyo_set_string(head, domain->domainname->name);
                tomoyo_set_lf(head);
        }
        head->r.eof = true;
}

/**
 * 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)
{
        head->r.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 void tomoyo_read_pid(struct tomoyo_io_buffer *head)
{
        char *buf = head->write_buf;
        bool global_pid = false;
        unsigned int pid;
        struct task_struct *p;
        struct tomoyo_domain_info *domain = NULL;

        /* Accessing write_buf is safe because head->io_sem is held. */
        if (!buf) {
                head->r.eof = true;
                return; /* Do nothing if open(O_RDONLY). */
        }
        if (head->r.w_pos || head->r.eof)
                return;
        head->r.eof = true;
        if (tomoyo_str_starts(&buf, "global-pid "))
                global_pid = true;
        pid = (unsigned int) simple_strtoul(buf, NULL, 10);
        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();
        if (!domain)
                return;
        tomoyo_io_printf(head, "%u %u ", pid, domain->profile);
        tomoyo_set_string(head, domain->domainname->name);
}

static const char *tomoyo_transition_type[TOMOYO_MAX_TRANSITION_TYPE] = {
        [TOMOYO_TRANSITION_CONTROL_NO_INITIALIZE]
        = TOMOYO_KEYWORD_NO_INITIALIZE_DOMAIN,
        [TOMOYO_TRANSITION_CONTROL_INITIALIZE]
        = TOMOYO_KEYWORD_INITIALIZE_DOMAIN,
        [TOMOYO_TRANSITION_CONTROL_NO_KEEP] = TOMOYO_KEYWORD_NO_KEEP_DOMAIN,
        [TOMOYO_TRANSITION_CONTROL_KEEP] = TOMOYO_KEYWORD_KEEP_DOMAIN
};

static const char *tomoyo_group_name[TOMOYO_MAX_GROUP] = {
        [TOMOYO_PATH_GROUP] = TOMOYO_KEYWORD_PATH_GROUP,
        [TOMOYO_NUMBER_GROUP] = TOMOYO_KEYWORD_NUMBER_GROUP
};

/**
 * tomoyo_write_exception - 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(struct tomoyo_io_buffer *head)
{
        char *data = head->write_buf;
        bool is_delete = tomoyo_str_starts(&data, TOMOYO_KEYWORD_DELETE);
        u8 i;
        static const struct {
                const char *keyword;
                int (*write) (char *, const bool);
        } tomoyo_callback[4] = {
                { TOMOYO_KEYWORD_AGGREGATOR, tomoyo_write_aggregator },
                { TOMOYO_KEYWORD_FILE_PATTERN, tomoyo_write_pattern },
                { TOMOYO_KEYWORD_DENY_REWRITE, tomoyo_write_no_rewrite },
                { TOMOYO_KEYWORD_ALLOW_READ, tomoyo_write_globally_readable },
        };

        for (i = 0; i < TOMOYO_MAX_TRANSITION_TYPE; i++)
                if (tomoyo_str_starts(&data, tomoyo_transition_type[i]))
                        return tomoyo_write_transition_control(data, is_delete,
                                                               i);
        for (i = 0; i < 4; i++)
                if (tomoyo_str_starts(&data, tomoyo_callback[i].keyword))
                        return tomoyo_callback[i].write(data, is_delete);
        for (i = 0; i < TOMOYO_MAX_GROUP; i++)
                if (tomoyo_str_starts(&data, tomoyo_group_name[i]))
                        return tomoyo_write_group(data, is_delete, i);
        return -EINVAL;
}

/**
 * tomoyo_read_group - Read "struct tomoyo_path_group"/"struct tomoyo_number_group" list.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 * @idx:  Index number.
 *
 * Returns true on success, false otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
static bool tomoyo_read_group(struct tomoyo_io_buffer *head, const int idx)
{
        list_for_each_cookie(head->r.group, &tomoyo_group_list[idx]) {
                struct tomoyo_group *group =
                        list_entry(head->r.group, typeof(*group), list);
                list_for_each_cookie(head->r.acl, &group->member_list) {
                        struct tomoyo_acl_head *ptr =
                                list_entry(head->r.acl, typeof(*ptr), list);
                        if (ptr->is_deleted)
                                continue;
                        if (!tomoyo_flush(head))
                                return false;
                        tomoyo_set_string(head, tomoyo_group_name[idx]);
                        tomoyo_set_string(head, group->group_name->name);
                        if (idx == TOMOYO_PATH_GROUP) {
                                tomoyo_set_space(head);
                                tomoyo_set_string(head, container_of
                                               (ptr, struct tomoyo_path_group,
                                                head)->member_name->name);
                        } else if (idx == TOMOYO_NUMBER_GROUP) {
                                tomoyo_print_number_union(head, &container_of
                                                          (ptr,
                                                   struct tomoyo_number_group,
                                                           head)->number);
                        }
                        tomoyo_set_lf(head);
                }
                head->r.acl = NULL;
        }
        head->r.group = NULL;
        return true;
}

/**
 * tomoyo_read_policy - Read "struct tomoyo_..._entry" list.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 * @idx:  Index number.
 *
 * Returns true on success, false otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
static bool tomoyo_read_policy(struct tomoyo_io_buffer *head, const int idx)
{
        list_for_each_cookie(head->r.acl, &tomoyo_policy_list[idx]) {
                struct tomoyo_acl_head *acl =
                        container_of(head->r.acl, typeof(*acl), list);
                if (acl->is_deleted)
                        continue;
                if (!tomoyo_flush(head))
                        return false;
                switch (idx) {
                case TOMOYO_ID_TRANSITION_CONTROL:
                        {
                                struct tomoyo_transition_control *ptr =
                                        container_of(acl, typeof(*ptr), head);
                                tomoyo_set_string(head,
                                                  tomoyo_transition_type
                                                  [ptr->type]);
                                if (ptr->program)
                                        tomoyo_set_string(head,
                                                          ptr->program->name);
                                if (ptr->program && ptr->domainname)
                                        tomoyo_set_string(head, " from ");
                                if (ptr->domainname)
                                        tomoyo_set_string(head,
                                                          ptr->domainname->
                                                          name);
                        }
                        break;
                case TOMOYO_ID_GLOBALLY_READABLE:
                        {
                                struct tomoyo_readable_file *ptr =
                                        container_of(acl, typeof(*ptr), head);
                                tomoyo_set_string(head,
                                                  TOMOYO_KEYWORD_ALLOW_READ);
                                tomoyo_set_string(head, ptr->filename->name);
                        }
                        break;
                case TOMOYO_ID_AGGREGATOR:
                        {
                                struct tomoyo_aggregator *ptr =
                                        container_of(acl, typeof(*ptr), head);
                                tomoyo_set_string(head,
                                                  TOMOYO_KEYWORD_AGGREGATOR);
                                tomoyo_set_string(head,
                                                  ptr->original_name->name);
                                tomoyo_set_space(head);
                                tomoyo_set_string(head,
                                               ptr->aggregated_name->name);
                        }
                        break;
                case TOMOYO_ID_PATTERN:
                        {
                                struct tomoyo_no_pattern *ptr =
                                        container_of(acl, typeof(*ptr), head);
                                tomoyo_set_string(head,
                                                  TOMOYO_KEYWORD_FILE_PATTERN);
                                tomoyo_set_string(head, ptr->pattern->name);
                        }
                        break;
                case TOMOYO_ID_NO_REWRITE:
                        {
                                struct tomoyo_no_rewrite *ptr =
                                        container_of(acl, typeof(*ptr), head);
                                tomoyo_set_string(head,
                                                  TOMOYO_KEYWORD_DENY_REWRITE);
                                tomoyo_set_string(head, ptr->pattern->name);
                        }
                        break;
                default:
                        continue;
                }
                tomoyo_set_lf(head);
        }
        head->r.acl = NULL;
        return true;
}

/**
 * tomoyo_read_exception - Read exception policy.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Caller holds tomoyo_read_lock().
 */
static void tomoyo_read_exception(struct tomoyo_io_buffer *head)
{
        if (head->r.eof)
                return;
        while (head->r.step < TOMOYO_MAX_POLICY &&
               tomoyo_read_policy(head, head->r.step))
                head->r.step++;
        if (head->r.step < TOMOYO_MAX_POLICY)
                return;
        while (head->r.step < TOMOYO_MAX_POLICY + TOMOYO_MAX_GROUP &&
               tomoyo_read_group(head, head->r.step - TOMOYO_MAX_POLICY))
                head->r.step++;
        if (head->r.step < TOMOYO_MAX_POLICY + TOMOYO_MAX_GROUP)
                return;
        head->r.eof = true;
}

/**
 * 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)
{
        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);
        pid_t ppid;
        if (!buffer)
                return NULL;
        do_gettimeofday(&tv);
        rcu_read_lock();
        ppid = task_tgid_vnr(current->real_parent);
        rcu_read_unlock();
        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[r->mode], gpid,
                 task_tgid_vnr(current), ppid,
                 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 {
        struct list_head list;
        char *query;
        int query_len;
        unsigned int serial;
        int timer;
        int answer;
};

/* The list for "struct tomoyo_query". */
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 = 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_domain2(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;
        entry = kzalloc(sizeof(*entry), GFP_NOFS);
        if (!entry)
                goto out;
        entry->query = kzalloc(len, GFP_NOFS);
        if (!entry->query)
                goto out;
        len = ksize(entry->query);
        spin_lock(&tomoyo_query_list_lock);
        if (tomoyo_quota_for_query && tomoyo_query_memory_size + len +
            sizeof(*entry) >= tomoyo_quota_for_query) {
                quota_exceeded = true;
        } else {
                tomoyo_query_memory_size += len + sizeof(*entry);
                entry->serial = tomoyo_serial++;
        }
        spin_unlock(&tomoyo_query_list_lock);
        if (quota_exceeded)
                goto out;
        pos = snprintf(entry->query, len - 1, "Q%u-%hu\n%s",
                       entry->serial, r->retry, header);
        kfree(header);
        header = NULL;
        va_start(args, fmt);
        vsnprintf(entry->query + pos, len - 1 - pos, fmt, args);
        entry->query_len = strlen(entry->query) + 1;
        va_end(args);
        spin_lock(&tomoyo_query_list_lock);
        list_add_tail(&entry->list, &tomoyo_query_list);
        spin_unlock(&tomoyo_query_list_lock);
        /* Give 10 seconds for supervisor's opinion. */
        for (entry->timer = 0;
             atomic_read(&tomoyo_query_observers) && entry->timer < 100;
             entry->timer++) {
                wake_up(&tomoyo_query_wait);
                set_current_state(TASK_INTERRUPTIBLE);
                schedule_timeout(HZ / 10);
                if (entry->answer)
                        break;
        }
        spin_lock(&tomoyo_query_list_lock);
        list_del(&entry->list);
        tomoyo_query_memory_size -= len + sizeof(*entry);
        spin_unlock(&tomoyo_query_list_lock);
        switch (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 (entry)
                kfree(entry->query);
        kfree(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 *ptr =
                                list_entry(tmp, typeof(*ptr), 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".
 */
static void tomoyo_read_query(struct tomoyo_io_buffer *head)
{
        struct list_head *tmp;
        int pos = 0;
        int len = 0;
        char *buf;
        if (head->r.w_pos)
                return;
        if (head->read_buf) {
                kfree(head->read_buf);
                head->read_buf = NULL;
        }
        spin_lock(&tomoyo_query_list_lock);
        list_for_each(tmp, &tomoyo_query_list) {
                struct tomoyo_query *ptr = list_entry(tmp, typeof(*ptr), list);
                if (ptr->answer)
                        continue;
                if (pos++ != head->r.query_index)
                        continue;
                len = ptr->query_len;
                break;
        }
        spin_unlock(&tomoyo_query_list_lock);
        if (!len) {
                head->r.query_index = 0;
                return;
        }
        buf = kzalloc(len, GFP_NOFS);
        if (!buf)
                return;
        pos = 0;
        spin_lock(&tomoyo_query_list_lock);
        list_for_each(tmp, &tomoyo_query_list) {
                struct tomoyo_query *ptr = list_entry(tmp, typeof(*ptr), list);
                if (ptr->answer)
                        continue;
                if (pos++ != head->r.query_index)
                        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_buf = buf;
                head->r.w[head->r.w_pos++] = buf;
                head->r.query_index++;
        } else {
                kfree(buf);
        }
}

/**
 * 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 *ptr = list_entry(tmp, typeof(*ptr), 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 *ptr = list_entry(tmp, typeof(*ptr), 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 void tomoyo_read_version(struct tomoyo_io_buffer *head)
{
        if (!head->r.eof) {
                tomoyo_io_printf(head, "2.3.0");
                head->r.eof = true;
        }
}

/**
 * tomoyo_read_self_domain - Get the current process's domainname.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns the current process's domainname.
 */
static void tomoyo_read_self_domain(struct tomoyo_io_buffer *head)
{
        if (!head->r.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->r.eof = true;
        }
}

/**
 * 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;
                head->read = tomoyo_read_domain;
                break;
        case TOMOYO_EXCEPTIONPOLICY:
                /* /sys/kernel/security/tomoyo/exception_policy */
                head->write = tomoyo_write_exception;
                head->read = tomoyo_read_exception;
                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;
                head->read = tomoyo_read_manager;
                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;
        struct tomoyo_io_buffer *head = file->private_data;

        if (!head->read)
                return -ENOSYS;
        if (mutex_lock_interruptible(&head->io_sem))
                return -EINTR;
        head->read_user_buf = buffer;
        head->read_user_buf_avail = buffer_len;
        if (tomoyo_flush(head))
                /* Call the policy handler. */
                head->read(head);
        tomoyo_flush(head);
        len = head->read_user_buf - buffer;
        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 && !tomoyo_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;
                printk(KERN_ERR "You need to define profile %u before using it.\n",
                       profile);
                printk(KERN_ERR "Please see http://tomoyo.sourceforge.jp/2.3/ "
                       "for more information.\n");
                panic("Profile %u (used by '%s') not defined.\n",
                      profile, domain->domainname->name);
        }
        tomoyo_read_unlock(idx);
        if (tomoyo_profile_version != 20090903) {
                printk(KERN_ERR "You need to install userland programs for "
                       "TOMOYO 2.3 and initialize policy configuration.\n");
                printk(KERN_ERR "Please see http://tomoyo.sourceforge.jp/2.3/ "
                       "for more information.\n");
                panic("Profile version %u is not supported.\n",
                      tomoyo_profile_version);
        }
        printk(KERN_INFO "TOMOYO: 2.3.0\n");
        printk(KERN_INFO "Mandatory Access Control activated.\n");
}