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 "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;
		}
		if (*w) {
			head->r.w[0] = 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")) {
		const struct tomoyo_path_info *old_comment = profile->comment;
		profile->comment = tomoyo_get_name(cp);
		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;
	head->r.eof = !domain;
	head->r.domain = &domain->list;
	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);
	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[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 {
	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;
		panic("Profile %u (used by '%s') not defined.\n",
		      profile, domain->domainname->name);
	}
	tomoyo_read_unlock(idx);
	if (tomoyo_profile_version != 20090903)
		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");
}