TOMOYO: Add garbage collector.

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

/*
 * security/tomoyo/common.c
 *
 * Common functions for TOMOYO.
 *
 * Copyright (C) 2005-2009  NTT DATA CORPORATION
 *
 * Version: 2.2.0   2009/04/01
 *
 */

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

/* Lock for protecting policy. */
DEFINE_MUTEX(tomoyo_policy_lock);

/* Has loading policy done? */
bool tomoyo_policy_loaded;

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

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

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

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

/* Utility functions. */

/* Open operation for /sys/kernel/security/tomoyo/ interface. */
static int tomoyo_open_control(const u8 type, struct file *file);
/* Close /sys/kernel/security/tomoyo/ interface. */
static int tomoyo_close_control(struct file *file);
/* Read operation for /sys/kernel/security/tomoyo/ interface. */
static int tomoyo_read_control(struct file *file, char __user *buffer,
                               const int buffer_len);
/* Write operation for /sys/kernel/security/tomoyo/ interface. */
static int tomoyo_write_control(struct file *file, const char __user *buffer,
                                const int buffer_len);

/**
 * tomoyo_is_byte_range - Check whether the string isa \ooo style octal value.
 *
 * @str: Pointer to the string.
 *
 * Returns true if @str is a \ooo style octal value, false otherwise.
 *
 * TOMOYO uses \ooo style representation for 0x01 - 0x20 and 0x7F - 0xFF.
 * This function verifies that \ooo is in valid range.
 */
static inline bool tomoyo_is_byte_range(const char *str)
{
        return *str >= '0' && *str++ <= '3' &&
                *str >= '0' && *str++ <= '7' &&
                *str >= '0' && *str <= '7';
}

/**
 * tomoyo_is_alphabet_char - Check whether the character is an alphabet.
 *
 * @c: The character to check.
 *
 * Returns true if @c is an alphabet character, false otherwise.
 */
static inline bool tomoyo_is_alphabet_char(const char c)
{
        return (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z');
}

/**
 * tomoyo_make_byte - Make byte value from three octal characters.
 *
 * @c1: The first character.
 * @c2: The second character.
 * @c3: The third character.
 *
 * Returns byte value.
 */
static inline u8 tomoyo_make_byte(const u8 c1, const u8 c2, const u8 c3)
{
        return ((c1 - '0') << 6) + ((c2 - '0') << 3) + (c3 - '0');
}

/**
 * tomoyo_str_starts - Check whether the given string starts with the given keyword.
 *
 * @src:  Pointer to pointer to the string.
 * @find: Pointer to the keyword.
 *
 * Returns true if @src starts with @find, false otherwise.
 *
 * The @src is updated to point the first character after the @find
 * if @src starts with @find.
 */
static bool tomoyo_str_starts(char **src, const char *find)
{
        const int len = strlen(find);
        char *tmp = *src;

        if (strncmp(tmp, find, len))
                return false;
        tmp += len;
        *src = tmp;
        return true;
}

/**
 * tomoyo_normalize_line - Format string.
 *
 * @buffer: The line to normalize.
 *
 * Leading and trailing whitespaces are removed.
 * Multiple whitespaces are packed into single space.
 *
 * Returns nothing.
 */
static void tomoyo_normalize_line(unsigned char *buffer)
{
        unsigned char *sp = buffer;
        unsigned char *dp = buffer;
        bool first = true;

        while (tomoyo_is_invalid(*sp))
                sp++;
        while (*sp) {
                if (!first)
                        *dp++ = ' ';
                first = false;
                while (tomoyo_is_valid(*sp))
                        *dp++ = *sp++;
                while (tomoyo_is_invalid(*sp))
                        sp++;
        }
        *dp = '\0';
}

/**
 * tomoyo_is_correct_path - Validate a pathname.
 * @filename:     The pathname to check.
 * @start_type:   Should the pathname start with '/'?
 *                1 = must / -1 = must not / 0 = don't care
 * @pattern_type: Can the pathname contain a wildcard?
 *                1 = must / -1 = must not / 0 = don't care
 * @end_type:     Should the pathname end with '/'?
 *                1 = must / -1 = must not / 0 = don't care
 * @function:     The name of function calling me.
 *
 * Check whether the given filename follows the naming rules.
 * Returns true if @filename follows the naming rules, false otherwise.
 */
bool tomoyo_is_correct_path(const char *filename, const s8 start_type,
                            const s8 pattern_type, const s8 end_type,
                            const char *function)
{
        const char *const start = filename;
        bool in_repetition = false;
        bool contains_pattern = false;
        unsigned char c;
        unsigned char d;
        unsigned char e;
        const char *original_filename = filename;

        if (!filename)
                goto out;
        c = *filename;
        if (start_type == 1) { /* Must start with '/' */
                if (c != '/')
                        goto out;
        } else if (start_type == -1) { /* Must not start with '/' */
                if (c == '/')
                        goto out;
        }
        if (c)
                c = *(filename + strlen(filename) - 1);
        if (end_type == 1) { /* Must end with '/' */
                if (c != '/')
                        goto out;
        } else if (end_type == -1) { /* Must not end with '/' */
                if (c == '/')
                        goto out;
        }
        while (1) {
                c = *filename++;
                if (!c)
                        break;
                if (c == '\\') {
                        c = *filename++;
                        switch (c) {
                        case '\\':  /* "\\" */
                                continue;
                        case '$':   /* "\$" */
                        case '+':   /* "\+" */
                        case '?':   /* "\?" */
                        case '*':   /* "\*" */
                        case '@':   /* "\@" */
                        case 'x':   /* "\x" */
                        case 'X':   /* "\X" */
                        case 'a':   /* "\a" */
                        case 'A':   /* "\A" */
                        case '-':   /* "\-" */
                                if (pattern_type == -1)
                                        break; /* Must not contain pattern */
                                contains_pattern = true;
                                continue;
                        case '{':   /* "/\{" */
                                if (filename - 3 < start ||
                                    *(filename - 3) != '/')
                                        break;
                                if (pattern_type == -1)
                                        break; /* Must not contain pattern */
                                contains_pattern = true;
                                in_repetition = true;
                                continue;
                        case '}':   /* "\}/" */
                                if (*filename != '/')
                                        break;
                                if (!in_repetition)
                                        break;
                                in_repetition = false;
                                continue;
                        case '0':   /* "\ooo" */
                        case '1':
                        case '2':
                        case '3':
                                d = *filename++;
                                if (d < '0' || d > '7')
                                        break;
                                e = *filename++;
                                if (e < '0' || e > '7')
                                        break;
                                c = tomoyo_make_byte(c, d, e);
                                if (tomoyo_is_invalid(c))
                                        continue; /* pattern is not \000 */
                        }
                        goto out;
                } else if (in_repetition && c == '/') {
                        goto out;
                } else if (tomoyo_is_invalid(c)) {
                        goto out;
                }
        }
        if (pattern_type == 1) { /* Must contain pattern */
                if (!contains_pattern)
                        goto out;
        }
        if (in_repetition)
                goto out;
        return true;
 out:
        printk(KERN_DEBUG "%s: Invalid pathname '%s'\n", function,
               original_filename);
        return false;
}

/**
 * tomoyo_is_correct_domain - Check whether the given domainname follows the naming rules.
 * @domainname:   The domainname to check.
 * @function:     The name of function calling me.
 *
 * Returns true if @domainname follows the naming rules, false otherwise.
 */
bool tomoyo_is_correct_domain(const unsigned char *domainname,
                              const char *function)
{
        unsigned char c;
        unsigned char d;
        unsigned char e;
        const char *org_domainname = domainname;

        if (!domainname || strncmp(domainname, TOMOYO_ROOT_NAME,
                                   TOMOYO_ROOT_NAME_LEN))
                goto out;
        domainname += TOMOYO_ROOT_NAME_LEN;
        if (!*domainname)
                return true;
        do {
                if (*domainname++ != ' ')
                        goto out;
                if (*domainname++ != '/')
                        goto out;
                while ((c = *domainname) != '\0' && c != ' ') {
                        domainname++;
                        if (c == '\\') {
                                c = *domainname++;
                                switch ((c)) {
                                case '\\':  /* "\\" */
                                        continue;
                                case '0':   /* "\ooo" */
                                case '1':
                                case '2':
                                case '3':
                                        d = *domainname++;
                                        if (d < '0' || d > '7')
                                                break;
                                        e = *domainname++;
                                        if (e < '0' || e > '7')
                                                break;
                                        c = tomoyo_make_byte(c, d, e);
                                        if (tomoyo_is_invalid(c))
                                                /* pattern is not \000 */
                                                continue;
                                }
                                goto out;
                        } else if (tomoyo_is_invalid(c)) {
                                goto out;
                        }
                }
        } while (*domainname);
        return true;
 out:
        printk(KERN_DEBUG "%s: Invalid domainname '%s'\n", function,
               org_domainname);
        return false;
}

/**
 * tomoyo_is_domain_def - Check whether the given token can be a domainname.
 *
 * @buffer: The token to check.
 *
 * Returns true if @buffer possibly be a domainname, false otherwise.
 */
bool tomoyo_is_domain_def(const unsigned char *buffer)
{
        return !strncmp(buffer, TOMOYO_ROOT_NAME, TOMOYO_ROOT_NAME_LEN);
}

/**
 * tomoyo_find_domain - Find a domain by the given name.
 *
 * @domainname: The domainname to find.
 *
 * Returns pointer to "struct tomoyo_domain_info" if found, NULL otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
struct tomoyo_domain_info *tomoyo_find_domain(const char *domainname)
{
        struct tomoyo_domain_info *domain;
        struct tomoyo_path_info name;

        name.name = domainname;
        tomoyo_fill_path_info(&name);
        list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
                if (!domain->is_deleted &&
                    !tomoyo_pathcmp(&name, domain->domainname))
                        return domain;
        }
        return NULL;
}

/**
 * tomoyo_const_part_length - Evaluate the initial length without a pattern in a token.
 *
 * @filename: The string to evaluate.
 *
 * Returns the initial length without a pattern in @filename.
 */
static int tomoyo_const_part_length(const char *filename)
{
        char c;
        int len = 0;

        if (!filename)
                return 0;
        while ((c = *filename++) != '\0') {
                if (c != '\\') {
                        len++;
                        continue;
                }
                c = *filename++;
                switch (c) {
                case '\\':  /* "\\" */
                        len += 2;
                        continue;
                case '0':   /* "\ooo" */
                case '1':
                case '2':
                case '3':
                        c = *filename++;
                        if (c < '0' || c > '7')
                                break;
                        c = *filename++;
                        if (c < '0' || c > '7')
                                break;
                        len += 4;
                        continue;
                }
                break;
        }
        return len;
}

/**
 * tomoyo_fill_path_info - Fill in "struct tomoyo_path_info" members.
 *
 * @ptr: Pointer to "struct tomoyo_path_info" to fill in.
 *
 * The caller sets "struct tomoyo_path_info"->name.
 */
void tomoyo_fill_path_info(struct tomoyo_path_info *ptr)
{
        const char *name = ptr->name;
        const int len = strlen(name);

        ptr->const_len = tomoyo_const_part_length(name);
        ptr->is_dir = len && (name[len - 1] == '/');
        ptr->is_patterned = (ptr->const_len < len);
        ptr->hash = full_name_hash(name, len);
}

/**
 * tomoyo_file_matches_pattern2 - Pattern matching without '/' character
 * and "\-" pattern.
 *
 * @filename:     The start of string to check.
 * @filename_end: The end of string to check.
 * @pattern:      The start of pattern to compare.
 * @pattern_end:  The end of pattern to compare.
 *
 * Returns true if @filename matches @pattern, false otherwise.
 */
static bool tomoyo_file_matches_pattern2(const char *filename,
                                         const char *filename_end,
                                         const char *pattern,
                                         const char *pattern_end)
{
        while (filename < filename_end && pattern < pattern_end) {
                char c;
                if (*pattern != '\\') {
                        if (*filename++ != *pattern++)
                                return false;
                        continue;
                }
                c = *filename;
                pattern++;
                switch (*pattern) {
                        int i;
                        int j;
                case '?':
                        if (c == '/') {
                                return false;
                        } else if (c == '\\') {
                                if (filename[1] == '\\')
                                        filename++;
                                else if (tomoyo_is_byte_range(filename + 1))
                                        filename += 3;
                                else
                                        return false;
                        }
                        break;
                case '\\':
                        if (c != '\\')
                                return false;
                        if (*++filename != '\\')
                                return false;
                        break;
                case '+':
                        if (!isdigit(c))
                                return false;
                        break;
                case 'x':
                        if (!isxdigit(c))
                                return false;
                        break;
                case 'a':
                        if (!tomoyo_is_alphabet_char(c))
                                return false;
                        break;
                case '0':
                case '1':
                case '2':
                case '3':
                        if (c == '\\' && tomoyo_is_byte_range(filename + 1)
                            && strncmp(filename + 1, pattern, 3) == 0) {
                                filename += 3;
                                pattern += 2;
                                break;
                        }
                        return false; /* Not matched. */
                case '*':
                case '@':
                        for (i = 0; i <= filename_end - filename; i++) {
                                if (tomoyo_file_matches_pattern2(
                                                    filename + i, filename_end,
                                                    pattern + 1, pattern_end))
                                        return true;
                                c = filename[i];
                                if (c == '.' && *pattern == '@')
                                        break;
                                if (c != '\\')
                                        continue;
                                if (filename[i + 1] == '\\')
                                        i++;
                                else if (tomoyo_is_byte_range(filename + i + 1))
                                        i += 3;
                                else
                                        break; /* Bad pattern. */
                        }
                        return false; /* Not matched. */
                default:
                        j = 0;
                        c = *pattern;
                        if (c == '$') {
                                while (isdigit(filename[j]))
                                        j++;
                        } else if (c == 'X') {
                                while (isxdigit(filename[j]))
                                        j++;
                        } else if (c == 'A') {
                                while (tomoyo_is_alphabet_char(filename[j]))
                                        j++;
                        }
                        for (i = 1; i <= j; i++) {
                                if (tomoyo_file_matches_pattern2(
                                                    filename + i, filename_end,
                                                    pattern + 1, pattern_end))
                                        return true;
                        }
                        return false; /* Not matched or bad pattern. */
                }
                filename++;
                pattern++;
        }
        while (*pattern == '\\' &&
               (*(pattern + 1) == '*' || *(pattern + 1) == '@'))
                pattern += 2;
        return filename == filename_end && pattern == pattern_end;
}

/**
 * tomoyo_file_matches_pattern - Pattern matching without without '/' character.
 *
 * @filename:     The start of string to check.
 * @filename_end: The end of string to check.
 * @pattern:      The start of pattern to compare.
 * @pattern_end:  The end of pattern to compare.
 *
 * Returns true if @filename matches @pattern, false otherwise.
 */
static bool tomoyo_file_matches_pattern(const char *filename,
                                           const char *filename_end,
                                           const char *pattern,
                                           const char *pattern_end)
{
        const char *pattern_start = pattern;
        bool first = true;
        bool result;

        while (pattern < pattern_end - 1) {
                /* Split at "\-" pattern. */
                if (*pattern++ != '\\' || *pattern++ != '-')
                        continue;
                result = tomoyo_file_matches_pattern2(filename,
                                                      filename_end,
                                                      pattern_start,
                                                      pattern - 2);
                if (first)
                        result = !result;
                if (result)
                        return false;
                first = false;
                pattern_start = pattern;
        }
        result = tomoyo_file_matches_pattern2(filename, filename_end,
                                              pattern_start, pattern_end);
        return first ? result : !result;
}

/**
 * tomoyo_path_matches_pattern2 - Do pathname pattern matching.
 *
 * @f: The start of string to check.
 * @p: The start of pattern to compare.
 *
 * Returns true if @f matches @p, false otherwise.
 */
static bool tomoyo_path_matches_pattern2(const char *f, const char *p)
{
        const char *f_delimiter;
        const char *p_delimiter;

        while (*f && *p) {
                f_delimiter = strchr(f, '/');
                if (!f_delimiter)
                        f_delimiter = f + strlen(f);
                p_delimiter = strchr(p, '/');
                if (!p_delimiter)
                        p_delimiter = p + strlen(p);
                if (*p == '\\' && *(p + 1) == '{')
                        goto recursive;
                if (!tomoyo_file_matches_pattern(f, f_delimiter, p,
                                                 p_delimiter))
                        return false;
                f = f_delimiter;
                if (*f)
                        f++;
                p = p_delimiter;
                if (*p)
                        p++;
        }
        /* Ignore trailing "\*" and "\@" in @pattern. */
        while (*p == '\\' &&
               (*(p + 1) == '*' || *(p + 1) == '@'))
                p += 2;
        return !*f && !*p;
 recursive:
        /*
         * The "\{" pattern is permitted only after '/' character.
         * This guarantees that below "*(p - 1)" is safe.
         * Also, the "\}" pattern is permitted only before '/' character
         * so that "\{" + "\}" pair will not break the "\-" operator.
         */
        if (*(p - 1) != '/' || p_delimiter <= p + 3 || *p_delimiter != '/' ||
            *(p_delimiter - 1) != '}' || *(p_delimiter - 2) != '\\')
                return false; /* Bad pattern. */
        do {
                /* Compare current component with pattern. */
                if (!tomoyo_file_matches_pattern(f, f_delimiter, p + 2,
                                                 p_delimiter - 2))
                        break;
                /* Proceed to next component. */
                f = f_delimiter;
                if (!*f)
                        break;
                f++;
                /* Continue comparison. */
                if (tomoyo_path_matches_pattern2(f, p_delimiter + 1))
                        return true;
                f_delimiter = strchr(f, '/');
        } while (f_delimiter);
        return false; /* Not matched. */
}

/**
 * tomoyo_path_matches_pattern - Check whether the given filename matches the given pattern.
 *
 * @filename: The filename to check.
 * @pattern:  The pattern to compare.
 *
 * Returns true if matches, false otherwise.
 *
 * The following patterns are available.
 *   \\     \ itself.
 *   \ooo   Octal representation of a byte.
 *   \*     Zero or more repetitions of characters other than '/'.
 *   \@     Zero or more repetitions of characters other than '/' or '.'.
 *   \?     1 byte character other than '/'.
 *   \$     One or more repetitions of decimal digits.
 *   \+     1 decimal digit.
 *   \X     One or more repetitions of hexadecimal digits.
 *   \x     1 hexadecimal digit.
 *   \A     One or more repetitions of alphabet characters.
 *   \a     1 alphabet character.
 *
 *   \-     Subtraction operator.
 *
 *   /\{dir\}/   '/' + 'One or more repetitions of dir/' (e.g. /dir/ /dir/dir/
 *               /dir/dir/dir/ ).
 */
bool tomoyo_path_matches_pattern(const struct tomoyo_path_info *filename,
                                 const struct tomoyo_path_info *pattern)
{
        const char *f = filename->name;
        const char *p = pattern->name;
        const int len = pattern->const_len;

        /* If @pattern doesn't contain pattern, I can use strcmp(). */
        if (!pattern->is_patterned)
                return !tomoyo_pathcmp(filename, pattern);
        /* Don't compare directory and non-directory. */
        if (filename->is_dir != pattern->is_dir)
                return false;
        /* Compare the initial length without patterns. */
        if (strncmp(f, p, len))
                return false;
        f += len;
        p += len;
        return tomoyo_path_matches_pattern2(f, p);
}

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

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

/**
 * tomoyo_get_exe - Get tomoyo_realpath() of current process.
 *
 * Returns the tomoyo_realpath() of current process on success, NULL otherwise.
 *
 * This function uses kzalloc(), so the caller must call kfree()
 * if this function didn't return NULL.
 */
static const char *tomoyo_get_exe(void)
{
        struct mm_struct *mm = current->mm;
        struct vm_area_struct *vma;
        const char *cp = NULL;

        if (!mm)
                return NULL;
        down_read(&mm->mmap_sem);
        for (vma = mm->mmap; vma; vma = vma->vm_next) {
                if ((vma->vm_flags & VM_EXECUTABLE) && vma->vm_file) {
                        cp = tomoyo_realpath_from_path(&vma->vm_file->f_path);
                        break;
                }
        }
        up_read(&mm->mmap_sem);
        return cp;
}

/**
 * tomoyo_get_msg - Get warning message.
 *
 * @is_enforce: Is it enforcing mode?
 *
 * Returns "ERROR" or "WARNING".
 */
const char *tomoyo_get_msg(const bool is_enforce)
{
        if (is_enforce)
                return "ERROR";
        else
                return "WARNING";
}

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

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

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

/**
 * tomoyo_domain_quota_is_ok - Check for domain's quota.
 *
 * @domain: Pointer to "struct tomoyo_domain_info".
 *
 * Returns true if the domain is not exceeded quota, false otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
bool tomoyo_domain_quota_is_ok(struct tomoyo_domain_info * const domain)
{
        unsigned int count = 0;
        struct tomoyo_acl_info *ptr;

        if (!domain)
                return true;
        list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) {
                switch (ptr->type) {
                        struct tomoyo_single_path_acl_record *acl;
                        u32 perm;
                        u8 i;
                case TOMOYO_TYPE_SINGLE_PATH_ACL:
                        acl = container_of(ptr,
                                           struct tomoyo_single_path_acl_record,
                                           head);
                        perm = acl->perm | (((u32) acl->perm_high) << 16);
                        for (i = 0; i < TOMOYO_MAX_SINGLE_PATH_OPERATION; i++)
                                if (perm & (1 << i))
                                        count++;
                        if (perm & (1 << TOMOYO_TYPE_READ_WRITE_ACL))
                                count -= 2;
                        break;
                case TOMOYO_TYPE_DOUBLE_PATH_ACL:
                        perm = container_of(ptr,
                                    struct tomoyo_double_path_acl_record,
                                            head)->perm;
                        for (i = 0; i < TOMOYO_MAX_DOUBLE_PATH_OPERATION; i++)
                                if (perm & (1 << i))
                                        count++;
                        break;
                }
        }
        if (count < tomoyo_check_flags(domain, TOMOYO_MAX_ACCEPT_ENTRY))
                return true;
        if (!domain->quota_warned) {
                domain->quota_warned = true;
                printk(KERN_WARNING "TOMOYO-WARNING: "
                       "Domain '%s' has so many ACLs to hold. "
                       "Stopped learning mode.\n", domain->domainname->name);
        }
        return false;
}

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

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

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

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

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

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

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

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

        if (tomoyo_is_domain_def(manager)) {
                if (!tomoyo_is_correct_domain(manager, __func__))
                        return -EINVAL;
                is_domain = true;
        } else {
                if (!tomoyo_is_correct_path(manager, 1, -1, -1, __func__))
                        return -EINVAL;
        }
        saved_manager = tomoyo_get_name(manager);
        if (!saved_manager)
                return -ENOMEM;
        if (!is_delete)
                entry = kmalloc(sizeof(*entry), GFP_KERNEL);
        mutex_lock(&tomoyo_policy_lock);
        list_for_each_entry_rcu(ptr, &tomoyo_policy_manager_list, list) {
                if (ptr->manager != saved_manager)
                        continue;
                ptr->is_deleted = is_delete;
                error = 0;
                break;
        }
        if (!is_delete && error && tomoyo_memory_ok(entry)) {
                entry->manager = saved_manager;
                saved_manager = NULL;
                entry->is_domain = is_domain;
                list_add_tail_rcu(&entry->list, &tomoyo_policy_manager_list);
                entry = NULL;
                error = 0;
        }
        mutex_unlock(&tomoyo_policy_lock);
        tomoyo_put_name(saved_manager);
        kfree(entry);
        return error;
}

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

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

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

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

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

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

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

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

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

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

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

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

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

/**
 * tomoyo_print_single_path_acl - Print a single path ACL entry.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 * @ptr:  Pointer to "struct tomoyo_single_path_acl_record".
 *
 * Returns true on success, false otherwise.
 */
static bool tomoyo_print_single_path_acl(struct tomoyo_io_buffer *head,
                                         struct tomoyo_single_path_acl_record *
                                         ptr)
{
        int pos;
        u8 bit;
        const char *atmark = "";
        const char *filename;
        const u32 perm = ptr->perm | (((u32) ptr->perm_high) << 16);

        filename = ptr->filename->name;
        for (bit = head->read_bit; bit < TOMOYO_MAX_SINGLE_PATH_OPERATION;
             bit++) {
                const char *msg;
                if (!(perm & (1 << bit)))
                        continue;
                /* Print "read/write" instead of "read" and "write". */
                if ((bit == TOMOYO_TYPE_READ_ACL ||
                     bit == TOMOYO_TYPE_WRITE_ACL)
                    && (perm & (1 << TOMOYO_TYPE_READ_WRITE_ACL)))
                        continue;
                msg = tomoyo_sp2keyword(bit);
                pos = head->read_avail;
                if (!tomoyo_io_printf(head, "allow_%s %s%s\n", msg,
                                      atmark, filename))
                        goto out;
        }
        head->read_bit = 0;
        return true;
 out:
        head->read_bit = bit;
        head->read_avail = pos;
        return false;
}

/**
 * tomoyo_print_double_path_acl - Print a double path ACL entry.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 * @ptr:  Pointer to "struct tomoyo_double_path_acl_record".
 *
 * Returns true on success, false otherwise.
 */
static bool tomoyo_print_double_path_acl(struct tomoyo_io_buffer *head,
                                         struct tomoyo_double_path_acl_record *
                                         ptr)
{
        int pos;
        const char *atmark1 = "";
        const char *atmark2 = "";
        const char *filename1;
        const char *filename2;
        const u8 perm = ptr->perm;
        u8 bit;

        filename1 = ptr->filename1->name;
        filename2 = ptr->filename2->name;
        for (bit = head->read_bit; bit < TOMOYO_MAX_DOUBLE_PATH_OPERATION;
             bit++) {
                const char *msg;
                if (!(perm & (1 << bit)))
                        continue;
                msg = tomoyo_dp2keyword(bit);
                pos = head->read_avail;
                if (!tomoyo_io_printf(head, "allow_%s %s%s %s%s\n", msg,
                                      atmark1, filename1, atmark2, filename2))
                        goto out;
        }
        head->read_bit = 0;
        return true;
 out:
        head->read_bit = bit;
        head->read_avail = pos;
        return false;
}

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

        if (acl_type == TOMOYO_TYPE_SINGLE_PATH_ACL) {
                struct tomoyo_single_path_acl_record *acl
                        = container_of(ptr,
                                       struct tomoyo_single_path_acl_record,
                                       head);
                return tomoyo_print_single_path_acl(head, acl);
        }
        if (acl_type == TOMOYO_TYPE_DOUBLE_PATH_ACL) {
                struct tomoyo_double_path_acl_record *acl
                        = container_of(ptr,
                                       struct tomoyo_double_path_acl_record,
                                       head);
                return tomoyo_print_double_path_acl(head, acl);
        }
        BUG(); /* This must not happen. */
        return false;
}

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

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

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

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

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

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

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

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

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

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

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

/* path to policy loader */
static const char *tomoyo_loader = "/sbin/tomoyo-init";

/**
 * tomoyo_policy_loader_exists - Check whether /sbin/tomoyo-init exists.
 *
 * Returns true if /sbin/tomoyo-init exists, false otherwise.
 */
static bool tomoyo_policy_loader_exists(void)
{
        /*
         * Don't activate MAC if the policy loader doesn't exist.
         * If the initrd includes /sbin/init but real-root-dev has not
         * mounted on / yet, activating MAC will block the system since
         * policies are not loaded yet.
         * Thus, let do_execve() call this function everytime.
         */
        struct path path;

        if (kern_path(tomoyo_loader, LOOKUP_FOLLOW, &path)) {
                printk(KERN_INFO "Not activating Mandatory Access Control now "
                       "since %s doesn't exist.\n", tomoyo_loader);
                return false;
        }
        path_put(&path);
        return true;
}

/**
 * tomoyo_load_policy - Run external policy loader to load policy.
 *
 * @filename: The program about to start.
 *
 * This function checks whether @filename is /sbin/init , and if so
 * invoke /sbin/tomoyo-init and wait for the termination of /sbin/tomoyo-init
 * and then continues invocation of /sbin/init.
 * /sbin/tomoyo-init reads policy files in /etc/tomoyo/ directory and
 * writes to /sys/kernel/security/tomoyo/ interfaces.
 *
 * Returns nothing.
 */
void tomoyo_load_policy(const char *filename)
{
        char *argv[2];
        char *envp[3];

        if (tomoyo_policy_loaded)
                return;
        /*
         * Check filename is /sbin/init or /sbin/tomoyo-start.
         * /sbin/tomoyo-start is a dummy filename in case where /sbin/init can't
         * be passed.
         * You can create /sbin/tomoyo-start by
         * "ln -s /bin/true /sbin/tomoyo-start".
         */
        if (strcmp(filename, "/sbin/init") &&
            strcmp(filename, "/sbin/tomoyo-start"))
                return;
        if (!tomoyo_policy_loader_exists())
                return;

        printk(KERN_INFO "Calling %s to load policy. Please wait.\n",
               tomoyo_loader);
        argv[0] = (char *) tomoyo_loader;
        argv[1] = NULL;
        envp[0] = "HOME=/";
        envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
        envp[2] = NULL;
        call_usermodehelper(argv[0], argv, envp, 1);

        printk(KERN_INFO "TOMOYO: 2.2.0   2009/04/01\n");
        printk(KERN_INFO "Mandatory Access Control activated.\n");
        tomoyo_policy_loaded = true;
        { /* Check all profiles currently assigned to domains are defined. */
                struct tomoyo_domain_info *domain;
                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_version: Get version.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns version information.
 */
static int tomoyo_read_version(struct tomoyo_io_buffer *head)
{
        if (!head->read_eof) {
                tomoyo_io_printf(head, "2.2.0");
                head->read_eof = true;
        }
        return 0;
}

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

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

        if (!head)
                return -ENOMEM;
        mutex_init(&head->io_sem);
        switch (type) {
        case TOMOYO_DOMAINPOLICY:
                /* /sys/kernel/security/tomoyo/domain_policy */
                head->write = tomoyo_write_domain_policy;
                head->read = tomoyo_read_domain_policy;
                break;
        case TOMOYO_EXCEPTIONPOLICY:
                /* /sys/kernel/security/tomoyo/exception_policy */
                head->write = tomoyo_write_exception_policy;
                head->read = tomoyo_read_exception_policy;
                break;
        case TOMOYO_SELFDOMAIN:
                /* /sys/kernel/security/tomoyo/self_domain */
                head->read = tomoyo_read_self_domain;
                break;
        case TOMOYO_DOMAIN_STATUS:
                /* /sys/kernel/security/tomoyo/.domain_status */
                head->write = tomoyo_write_domain_profile;
                head->read = tomoyo_read_domain_profile;
                break;
        case TOMOYO_PROCESS_STATUS:
                /* /sys/kernel/security/tomoyo/.process_status */
                head->write = tomoyo_write_pid;
                head->read = tomoyo_read_pid;
                break;
        case TOMOYO_VERSION:
                /* /sys/kernel/security/tomoyo/version */
                head->read = tomoyo_read_version;
                head->readbuf_size = 128;
                break;
        case TOMOYO_MEMINFO:
                /* /sys/kernel/security/tomoyo/meminfo */
                head->write = tomoyo_write_memory_quota;
                head->read = tomoyo_read_memory_counter;
                head->readbuf_size = 512;
                break;
        case TOMOYO_PROFILE:
                /* /sys/kernel/security/tomoyo/profile */
                head->write = tomoyo_write_profile;
                head->read = tomoyo_read_profile;
                break;
        case TOMOYO_MANAGER:
                /* /sys/kernel/security/tomoyo/manager */
                head->write = tomoyo_write_manager_policy;
                head->read = tomoyo_read_manager_policy;
                break;
        }
        if (!(file->f_mode & FMODE_READ)) {
                /*
                 * No need to allocate read_buf since it is not opened
                 * for reading.
                 */
                head->read = NULL;
        } else {
                if (!head->readbuf_size)
                        head->readbuf_size = 4096 * 2;
                head->read_buf = kzalloc(head->readbuf_size, GFP_KERNEL);
                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_KERNEL);
                if (!head->write_buf) {
                        kfree(head->read_buf);
                        kfree(head);
                        return -ENOMEM;
                }
        }
        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);
        return 0;
}

/**
 * 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().
 */
static int tomoyo_read_control(struct file *file, char __user *buffer,
                               const int buffer_len)
{
        int len = 0;
        struct tomoyo_io_buffer *head = file->private_data;
        char *cp;

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

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

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

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

        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_open - open() for /sys/kernel/security/tomoyo/ interface.
 *
 * @inode: Pointer to "struct inode".
 * @file:  Pointer to "struct file".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_open(struct inode *inode, struct file *file)
{
        const int key = ((u8 *) file->f_path.dentry->d_inode->i_private)
                - ((u8 *) NULL);
        return tomoyo_open_control(key, file);
}

/**
 * tomoyo_release - close() for /sys/kernel/security/tomoyo/ interface.
 *
 * @inode: Pointer to "struct inode".
 * @file:  Pointer to "struct file".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_release(struct inode *inode, struct file *file)
{
        return tomoyo_close_control(file);
}

/**
 * tomoyo_read - read() for /sys/kernel/security/tomoyo/ interface.
 *
 * @file:  Pointer to "struct file".
 * @buf:   Pointer to buffer.
 * @count: Size of @buf.
 * @ppos:  Unused.
 *
 * Returns bytes read on success, negative value otherwise.
 */
static ssize_t tomoyo_read(struct file *file, char __user *buf, size_t count,
                           loff_t *ppos)
{
        return tomoyo_read_control(file, buf, count);
}

/**
 * tomoyo_write - write() for /sys/kernel/security/tomoyo/ interface.
 *
 * @file:  Pointer to "struct file".
 * @buf:   Pointer to buffer.
 * @count: Size of @buf.
 * @ppos:  Unused.
 *
 * Returns @count on success, negative value otherwise.
 */
static ssize_t tomoyo_write(struct file *file, const char __user *buf,
                            size_t count, loff_t *ppos)
{
        return tomoyo_write_control(file, buf, count);
}

/*
 * tomoyo_operations is a "struct file_operations" which is used for handling
 * /sys/kernel/security/tomoyo/ interface.
 *
 * Some files under /sys/kernel/security/tomoyo/ directory accept open(O_RDWR).
 * See tomoyo_io_buffer for internals.
 */
static const struct file_operations tomoyo_operations = {
        .open    = tomoyo_open,
        .release = tomoyo_release,
        .read    = tomoyo_read,
        .write   = tomoyo_write,
};

/**
 * tomoyo_create_entry - Create interface files under /sys/kernel/security/tomoyo/ directory.
 *
 * @name:   The name of the interface file.
 * @mode:   The permission of the interface file.
 * @parent: The parent directory.
 * @key:    Type of interface.
 *
 * Returns nothing.
 */
static void __init tomoyo_create_entry(const char *name, const mode_t mode,
                                       struct dentry *parent, const u8 key)
{
        securityfs_create_file(name, mode, parent, ((u8 *) NULL) + key,
                               &tomoyo_operations);
}

/**
 * tomoyo_initerface_init - Initialize /sys/kernel/security/tomoyo/ interface.
 *
 * Returns 0.
 */
static int __init tomoyo_initerface_init(void)
{
        struct dentry *tomoyo_dir;

        /* Don't create securityfs entries unless registered. */
        if (current_cred()->security != &tomoyo_kernel_domain)
                return 0;

        tomoyo_dir = securityfs_create_dir("tomoyo", NULL);
        tomoyo_create_entry("domain_policy",    0600, tomoyo_dir,
                            TOMOYO_DOMAINPOLICY);
        tomoyo_create_entry("exception_policy", 0600, tomoyo_dir,
                            TOMOYO_EXCEPTIONPOLICY);
        tomoyo_create_entry("self_domain",      0400, tomoyo_dir,
                            TOMOYO_SELFDOMAIN);
        tomoyo_create_entry(".domain_status",   0600, tomoyo_dir,
                            TOMOYO_DOMAIN_STATUS);
        tomoyo_create_entry(".process_status",  0600, tomoyo_dir,
                            TOMOYO_PROCESS_STATUS);
        tomoyo_create_entry("meminfo",          0600, tomoyo_dir,
                            TOMOYO_MEMINFO);
        tomoyo_create_entry("profile",          0600, tomoyo_dir,
                            TOMOYO_PROFILE);
        tomoyo_create_entry("manager",          0600, tomoyo_dir,
                            TOMOYO_MANAGER);
        tomoyo_create_entry("version",          0400, tomoyo_dir,
                            TOMOYO_VERSION);
        return 0;
}

fs_initcall(tomoyo_initerface_init);