security/ccsecurity/util.c

/*
 * fs/ccs_common.c
 *
 * Common functions for SAKURA and TOMOYO.
 *
 * Copyright (C) 2005-2009  NTT DATA CORPORATION
 *
 * Version: 1.6.8-pre   2009/05/08
 *
 * This file is applicable to both 2.4.30 and 2.6.11 and later.
 * See README.ccs for ChangeLog.
 *
 */

#include <linux/version.h>
#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 5, 0)
#define __KERNEL_SYSCALLS__
#endif
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/utime.h>
#include <linux/file.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <stdarg.h>
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 5, 0)
#include <linux/namei.h>
#include <linux/mount.h>
static const int ccs_lookup_flags = LOOKUP_FOLLOW;
#else
static const int ccs_lookup_flags = LOOKUP_FOLLOW | LOOKUP_POSITIVE;
#endif
#include <linux/ccs_common.h>
#include <linux/realpath.h>
#include <linux/ccs_proc.h>
#include <linux/tomoyo.h>
#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 5, 0)
#include <linux/unistd.h>
#endif

/* To support PID namespace. */
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 24)
#define find_task_by_pid find_task_by_vpid
#endif

/* Set default specified by the kernel config. */
#ifdef CONFIG_TOMOYO
#define MAX_ACCEPT_ENTRY (CONFIG_TOMOYO_MAX_ACCEPT_ENTRY)
#define MAX_GRANT_LOG    (CONFIG_TOMOYO_MAX_GRANT_LOG)
#define MAX_REJECT_LOG   (CONFIG_TOMOYO_MAX_REJECT_LOG)
#else
#define MAX_ACCEPT_ENTRY 0
#define MAX_GRANT_LOG    0
#define MAX_REJECT_LOG   0
#endif

DECLARE_RWSEM(ccs_policy_lock);

/* Has /sbin/init started? */
bool ccs_policy_loaded;

/* Log level for SAKURA's printk(). */
const char *ccs_log_level = KERN_DEBUG;

/* String table for functionality that takes 4 modes. */
static const char *ccs_mode_4[4] = {
        "disabled", "learning", "permissive", "enforcing"
};
/* String table for functionality that takes 2 modes. */
static const char *ccs_mode_2[4] = {
        "disabled", "enabled", "enabled", "enabled"
};

/* Table for profile. */
static struct {
        const char *keyword;
        unsigned int current_value;
        const unsigned int max_value;
} ccs_control_array[CCS_MAX_CONTROL_INDEX] = {
        [CCS_MAC_FOR_FILE]        = { "MAC_FOR_FILE",        0, 3 },
        [CCS_MAC_FOR_IOCTL]       = { "MAC_FOR_IOCTL",       0, 3 },
        [CCS_MAC_FOR_ARGV0]       = { "MAC_FOR_ARGV0",       0, 3 },
        [CCS_MAC_FOR_ENV]         = { "MAC_FOR_ENV",         0, 3 },
        [CCS_MAC_FOR_NETWORK]     = { "MAC_FOR_NETWORK",     0, 3 },
        [CCS_MAC_FOR_SIGNAL]      = { "MAC_FOR_SIGNAL",      0, 3 },
        [CCS_DENY_CONCEAL_MOUNT]  = { "DENY_CONCEAL_MOUNT",  0, 3 },
        [CCS_RESTRICT_CHROOT]     = { "RESTRICT_CHROOT",     0, 3 },
        [CCS_RESTRICT_MOUNT]      = { "RESTRICT_MOUNT",      0, 3 },
        [CCS_RESTRICT_UNMOUNT]    = { "RESTRICT_UNMOUNT",    0, 3 },
        [CCS_RESTRICT_PIVOT_ROOT] = { "RESTRICT_PIVOT_ROOT", 0, 3 },
        [CCS_RESTRICT_AUTOBIND]   = { "RESTRICT_AUTOBIND",   0, 1 },
        [CCS_MAX_ACCEPT_ENTRY]
        = { "MAX_ACCEPT_ENTRY",    MAX_ACCEPT_ENTRY, INT_MAX },
#ifdef CONFIG_TOMOYO_AUDIT
        [CCS_MAX_GRANT_LOG]
        = { "MAX_GRANT_LOG",       MAX_GRANT_LOG, INT_MAX },
        [CCS_MAX_REJECT_LOG]
        = { "MAX_REJECT_LOG",      MAX_REJECT_LOG, INT_MAX },
#endif
        [CCS_VERBOSE]             = { "TOMOYO_VERBOSE",      1, 1 },
        [CCS_SLEEP_PERIOD]
        = { "SLEEP_PERIOD",        0, 3000 }, /* in 0.1 second */
};

#ifdef CONFIG_TOMOYO
/* Capability name used by domain policy. */
static const char *ccs_capability_control_keyword[CCS_MAX_CAPABILITY_INDEX]
= {
        [CCS_INET_STREAM_SOCKET_CREATE]  = "inet_tcp_create",
        [CCS_INET_STREAM_SOCKET_LISTEN]  = "inet_tcp_listen",
        [CCS_INET_STREAM_SOCKET_CONNECT] = "inet_tcp_connect",
        [CCS_USE_INET_DGRAM_SOCKET]      = "use_inet_udp",
        [CCS_USE_INET_RAW_SOCKET]        = "use_inet_ip",
        [CCS_USE_ROUTE_SOCKET]           = "use_route",
        [CCS_USE_PACKET_SOCKET]          = "use_packet",
        [CCS_SYS_MOUNT]                  = "SYS_MOUNT",
        [CCS_SYS_UMOUNT]                 = "SYS_UMOUNT",
        [CCS_SYS_REBOOT]                 = "SYS_REBOOT",
        [CCS_SYS_CHROOT]                 = "SYS_CHROOT",
        [CCS_SYS_KILL]                   = "SYS_KILL",
        [CCS_SYS_VHANGUP]                = "SYS_VHANGUP",
        [CCS_SYS_SETTIME]                = "SYS_TIME",
        [CCS_SYS_NICE]                   = "SYS_NICE",
        [CCS_SYS_SETHOSTNAME]            = "SYS_SETHOSTNAME",
        [CCS_USE_KERNEL_MODULE]          = "use_kernel_module",
        [CCS_CREATE_FIFO]                = "create_fifo",
        [CCS_CREATE_BLOCK_DEV]           = "create_block_dev",
        [CCS_CREATE_CHAR_DEV]            = "create_char_dev",
        [CCS_CREATE_UNIX_SOCKET]         = "create_unix_socket",
        [CCS_SYS_LINK]                   = "SYS_LINK",
        [CCS_SYS_SYMLINK]                = "SYS_SYMLINK",
        [CCS_SYS_RENAME]                 = "SYS_RENAME",
        [CCS_SYS_UNLINK]                 = "SYS_UNLINK",
        [CCS_SYS_CHMOD]                  = "SYS_CHMOD",
        [CCS_SYS_CHOWN]                  = "SYS_CHOWN",
        [CCS_SYS_IOCTL]                  = "SYS_IOCTL",
        [CCS_SYS_KEXEC_LOAD]             = "SYS_KEXEC_LOAD",
        [CCS_SYS_PIVOT_ROOT]             = "SYS_PIVOT_ROOT",
        [CCS_SYS_PTRACE]                 = "SYS_PTRACE",
};
#endif

#ifdef CONFIG_TOMOYO
static bool ccs_profile_entry_used[CCS_MAX_CONTROL_INDEX +
                                   CCS_MAX_CAPABILITY_INDEX + 1];
#else
static bool ccs_profile_entry_used[CCS_MAX_CONTROL_INDEX + 1];
#endif

/* Profile table. Memory is allocated as needed. */
static struct ccs_profile {
        unsigned int value[CCS_MAX_CONTROL_INDEX];
        const struct ccs_path_info *comment;
#ifdef CONFIG_TOMOYO
        unsigned char capability_value[CCS_MAX_CAPABILITY_INDEX];
#endif
} *ccs_profile_ptr[MAX_PROFILES];

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

/* Utility functions. */

#ifdef CONFIG_TOMOYO
/**
 * ccs_quiet_setup - Set CCS_VERBOSE=0 by default.
 *
 * @str: Unused.
 *
 * Returns 0.
 */
static int __init ccs_quiet_setup(char *str)
{
        ccs_control_array[CCS_VERBOSE].current_value = 0;
        return 0;
}

__setup("CCS_QUIET", ccs_quiet_setup);
#endif

/**
 * ccs_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.
 */
static inline bool ccs_is_byte_range(const char *str)
{
        return *str >= '0' && *str++ <= '3' &&
                *str >= '0' && *str++ <= '7' &&
                *str >= '0' && *str <= '7';
}

/**
 * ccs_is_decimal - Check whether the character is a decimal character.
 *
 * @c: The character to check.
 *
 * Returns true if @c is a decimal character, false otherwise.
 */
static inline bool ccs_is_decimal(const char c)
{
        return c >= '0' && c <= '9';
}

/**
 * ccs_is_hexadecimal - Check whether the character is a hexadecimal character.
 *
 * @c: The character to check.
 *
 * Returns true if @c is a hexadecimal character, false otherwise.
 */
static inline bool ccs_is_hexadecimal(const char c)
{
        return (c >= '0' && c <= '9') ||
                (c >= 'A' && c <= 'F') ||
                (c >= 'a' && c <= 'f');
}

/**
 * ccs_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 ccs_is_alphabet_char(const char c)
{
        return (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z');
}

/**
 * ccs_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 ccs_make_byte(const u8 c1, const u8 c2, const u8 c3)
{
        return ((c1 - '0') << 6) + ((c2 - '0') << 3) + (c3 - '0');
}

/**
 * ccs_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 ccs_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;
}

/**
 * ccs_normalize_line - Format string.
 *
 * @buffer: The line to normalize.
 *
 * Leading and trailing whitespaces are removed.
 * Multiple whitespaces are packed into single space.
 *
 * Returns nothing.
 */
void ccs_normalize_line(unsigned char *buffer)
{
        unsigned char *sp = buffer;
        unsigned char *dp = buffer;
        bool first = true;
        while (*sp && (*sp <= ' ' || *sp >= 127))
                sp++;
        while (*sp) {
                if (!first)
                        *dp++ = ' ';
                first = false;
                while (*sp > ' ' && *sp < 127)
                        *dp++ = *sp++;
                while (*sp && (*sp <= ' ' || *sp >= 127))
                        sp++;
        }
        *dp = '\0';
}

/**
 * ccs_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 ccs_is_correct_path(const char *filename, const s8 start_type,
                         const s8 pattern_type, const s8 end_type,
                         const char *function)
{
        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 '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 = ccs_make_byte(c, d, e);
                                if (c && (c <= ' ' || c >= 127))
                                        continue; /* pattern is not \000 */
                        }
                        goto out;
                } else if (c <= ' ' || c >= 127) {
                        goto out;
                }
        }
        if (pattern_type == 1) { /* Must contain pattern */
                if (!contains_pattern)
                        goto out;
        }
        return true;
 out:
        printk(KERN_DEBUG "%s: Invalid pathname '%s'\n", function,
               original_filename);
        return false;
}

/**
 * ccs_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 ccs_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, ROOT_NAME, ROOT_NAME_LEN))
                goto out;
        domainname += ROOT_NAME_LEN;
        if (!*domainname)
                return true;
        do {
                if (*domainname++ != ' ')
                        goto out;
                if (*domainname++ != '/')
                        goto out;
                while (1) {
                        c = *domainname;
                        if (!c || c == ' ')
                                break;
                        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 = ccs_make_byte(c, d, e);
                                        if (c && (c <= ' ' || c >= 127))
                                                /* pattern is not \000 */
                                                continue;
                                }
                                goto out;
                        } else if (c < ' ' || c >= 127) {
                                goto out;
                        }
                }
        } while (*domainname);
        return true;
 out:
        printk(KERN_DEBUG "%s: Invalid domainname '%s'\n", function,
               org_domainname);
        return false;
}

/**
 * ccs_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 ccs_is_domain_def(const unsigned char *buffer)
{
        return !strncmp(buffer, ROOT_NAME, ROOT_NAME_LEN);
}

/**
 * ccs_find_domain - Find a domain by the given name.
 *
 * @domainname: The domainname to find.
 * @cookie:     Pointer to "struct ccs_cookie".
 *
 * Returns true if found, false otherwise.
 */
bool ccs_find_domain(const char *domainname, struct ccs_cookie *cookie)
{
        struct ccs_domain_info *domain;
        struct ccs_path_info name;
        name.name = domainname;
        ccs_fill_path_info(&name);
        cookie->u.domain = NULL;
        /***** READER SECTION START *****/
        down_read(&ccs_policy_lock);
        list_for_each_entry(domain, &ccs_domain_list, list) {
                if (domain->is_deleted ||
                    ccs_pathcmp(&name, domain->domainname))
                        continue;
                cookie->u.domain = domain;
                break;
        }
        up_read(&ccs_policy_lock);
        /***** READER SECTION END *****/
        return cookie->u.domain != NULL;
}

/**
 * ccs_path_depth - Evaluate the number of '/' in a string.
 *
 * @pathname: The string to evaluate.
 *
 * Returns path depth of the string.
 *
 * I score 2 for each of the '/' in the @pathname
 * and score 1 if the @pathname ends with '/'.
 */
static int ccs_path_depth(const char *pathname)
{
        int i = 0;
        if (pathname) {
                const char *ep = pathname + strlen(pathname);
                if (pathname < ep--) {
                        if (*ep != '/')
                                i++;
                        while (pathname <= ep)
                                if (*ep-- == '/')
                                        i += 2;
                }
        }
        return i;
}

/**
 * ccs_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 ccs_const_part_length(const char *filename)
{
        char c;
        int len = 0;
        if (!filename)
                return 0;
        while (1) {
                c = *filename++;
                if (!c)
                        break;
                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;
}

/**
 * ccs_fill_path_info - Fill in "struct ccs_path_info" members.
 *
 * @ptr: Pointer to "struct ccs_path_info" to fill in.
 *
 * The caller sets "struct ccs_path_info"->name.
 */
void ccs_fill_path_info(struct ccs_path_info *ptr)
{
        const char *name = ptr->name;
        const int len = strlen(name);
        ptr->total_len = len;
        ptr->const_len = ccs_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);
        ptr->depth = ccs_path_depth(name);
}

/**
 * ccs_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 ccs_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 (ccs_is_byte_range(filename + 1))
                                        filename += 3;
                                else
                                        return false;
                        }
                        break;
                case '\\':
                        if (c != '\\')
                                return false;
                        if (*++filename != '\\')
                                return false;
                        break;
                case '+':
                        if (!ccs_is_decimal(c))
                                return false;
                        break;
                case 'x':
                        if (!ccs_is_hexadecimal(c))
                                return false;
                        break;
                case 'a':
                        if (!ccs_is_alphabet_char(c))
                                return false;
                        break;
                case '0':
                case '1':
                case '2':
                case '3':
                        if (c == '\\' && ccs_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 (ccs_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 (ccs_is_byte_range(filename + i + 1))
                                        i += 3;
                                else
                                        break; /* Bad pattern. */
                        }
                        return false; /* Not matched. */
                default:
                        j = 0;
                        c = *pattern;
                        if (c == '$') {
                                while (ccs_is_decimal(filename[j]))
                                        j++;
                        } else if (c == 'X') {
                                while (ccs_is_hexadecimal(filename[j]))
                                        j++;
                        } else if (c == 'A') {
                                while (ccs_is_alphabet_char(filename[j]))
                                        j++;
                        }
                        for (i = 1; i <= j; i++) {
                                if (ccs_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;
}

/**
 * ccs_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 ccs_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 = ccs_file_matches_pattern2(filename, filename_end,
                                                   pattern_start, pattern - 2);
                if (first)
                        result = !result;
                if (result)
                        return false;
                first = false;
                pattern_start = pattern;
        }
        result = ccs_file_matches_pattern2(filename, filename_end,
                                           pattern_start, pattern_end);
        return first ? result : !result;
}

/**
 * ccs_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.
 *   \*     More than or equals to 0 character other than '/'.
 *   \@     More than or equals to 0 character other than '/' or '.'.
 *   \?     1 byte character other than '/'.
 *   \$     More than or equals to 1 decimal digit.
 *   \+     1 decimal digit.
 *   \X     More than or equals to 1 hexadecimal digit.
 *   \x     1 hexadecimal digit.
 *   \A     More than or equals to 1 alphabet character.
 *   \a     1 alphabet character.
 *   \-     Subtraction operator.
 */
bool ccs_path_matches_pattern(const struct ccs_path_info *filename,
                              const struct ccs_path_info *pattern)
{
        /*
          if (!filename || !pattern)
          return false;
        */
        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 !ccs_pathcmp(filename, pattern);
        /* Dont compare if the number of '/' differs. */
        if (filename->depth != pattern->depth)
                return false;
        /* Compare the initial length without patterns. */
        if (strncmp(f, p, len))
                return false;
        f += len;
        p += len;
        /* Main loop. Compare each directory component. */
        while (*f && *p) {
                const char *f_delimiter = strchr(f, '/');
                const char *p_delimiter = strchr(p, '/');
                if (!f_delimiter)
                        f_delimiter = f + strlen(f);
                if (!p_delimiter)
                        p_delimiter = p + strlen(p);
                if (!ccs_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;
}

/**
 * ccs_io_printf - Transactional printf() to "struct ccs_io_buffer" structure.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 * @fmt:  The printf()'s format string, followed by parameters.
 *
 * Returns true on success, false otherwise.
 *
 * The snprintf() will truncate, but ccs_io_printf() won't.
 */
bool ccs_io_printf(struct ccs_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;
}

/**
 * ccs_get_exe - Get ccs_realpath() of current process.
 *
 * Returns the ccs_realpath() of current process on success, NULL otherwise.
 *
 * This function uses ccs_alloc(), so the caller must ccs_free()
 * if this function didn't return NULL.
 */
const char *ccs_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 = ccs_realpath_from_dentry(vma->vm_file->f_dentry,
                                                      vma->vm_file->f_vfsmnt);
                        break;
                }
        }
        up_read(&mm->mmap_sem);
        return cp;
}

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

/**
 * ccs_can_sleep - Check whether it is permitted to do operations that may sleep.
 *
 * Returns true if it is permitted to do operations that may sleep,
 * false otherwise.
 *
 * TOMOYO Linux supports interactive enforcement that lets processes
 * wait for the administrator's decision.
 * All hooks but the one for ccs_may_autobind() are inserted where
 * it is permitted to do operations that may sleep.
 * Thus, this warning should not happen.
 */
bool ccs_can_sleep(void)
{
        static u8 count = 20;
        if (likely(!in_interrupt()))
                return true;
        if (count) {
                count--;
                printk(KERN_ERR "BUG: sleeping function called "
                       "from invalid context.\n");
                dump_stack();
        }
        return false;
}

/**
 * ccs_check_flags - Check mode for specified functionality.
 *
 * @domain: Pointer to "struct ccs_domain_info". NULL for ccs_current_domain().
 * @index:  The functionality to check mode.
 *
 * Returns the mode of specified functionality.
 */
unsigned int ccs_check_flags(const struct ccs_domain_info *domain,
                             const u8 index)
{
        u8 profile;
        if (!domain)
                domain = ccs_current_domain();
        profile = domain->profile;
        return ccs_policy_loaded && index < CCS_MAX_CONTROL_INDEX
#if MAX_PROFILES != 256
                && profile < MAX_PROFILES
#endif
                && ccs_profile_ptr[profile] ?
                ccs_profile_ptr[profile]->value[index] : 0;
}

#ifdef CONFIG_TOMOYO
/**
 * ccs_check_capability_flags - Check mode for specified capability.
 *
 * @domain: Pointer to "struct ccs_domain_info". NULL for ccs_current_domain().
 * @index:  The capability to check mode.
 *
 * Returns the mode of specified capability.
 */
static u8 ccs_check_capability_flags(const struct ccs_domain_info *domain,
                                     const u8 index)
{
        const u8 profile = domain ? domain->profile :
                ccs_current_domain()->profile;
        return ccs_policy_loaded && index < CCS_MAX_CAPABILITY_INDEX
#if MAX_PROFILES != 256
                && profile < MAX_PROFILES
#endif
                && ccs_profile_ptr[profile] ?
                ccs_profile_ptr[profile]->capability_value[index] : 0;
}

/**
 * ccs_cap2keyword - Convert capability operation to capability name.
 *
 * @operation: The capability index.
 *
 * Returns the name of the specified capability's name.
 */
const char *ccs_cap2keyword(const u8 operation)
{
        return operation < CCS_MAX_CAPABILITY_INDEX
                ? ccs_capability_control_keyword[operation] : NULL;
}

#endif

/**
 * ccs_init_request_info - Initialize "struct ccs_request_info" members.
 *
 * @r:      Pointer to "struct ccs_request_info" to initialize.
 * @domain: Pointer to "struct ccs_domain_info". NULL for ccs_current_domain().
 * @index:  Index number of functionality.
 */
void ccs_init_request_info(struct ccs_request_info *r,
                           struct ccs_domain_info *domain, const u8 index)
{
        memset(r, 0, sizeof(*r));
        ccs_add_cookie(&r->cookie, NULL);
        ccs_add_cookie(&r->condition_cookie, NULL);
        if (!domain)
                domain = ccs_current_domain();
        r->cookie.u.domain = domain;
        r->profile = domain->profile;
        if (index < CCS_MAX_CONTROL_INDEX)
                r->mode = ccs_check_flags(domain, index);
#ifdef CONFIG_TOMOYO
        else
                r->mode = ccs_check_capability_flags(domain, index
                                                     - CCS_MAX_CONTROL_INDEX);
#endif
}

/**
 * ccs_exit_request_info - Cleanup "struct ccs_request_info" members.
 *
 * @r: Pointer to "struct ccs_request_info".
 */
void ccs_exit_request_info(struct ccs_request_info *r)
{
        ccs_del_cookie(&r->condition_cookie);
        ccs_del_cookie(&r->cookie);
}

/**
 * ccs_verbose_mode - Check whether TOMOYO is verbose mode.
 *
 * @domain: Pointer to "struct ccs_domain_info". NULL for ccs_current_domain().
 *
 * Returns true if domain policy violation warning should be printed to
 * console.
 */
bool ccs_verbose_mode(const struct ccs_domain_info *domain)
{
        return ccs_check_flags(domain, CCS_VERBOSE) != 0;
}

/**
 * ccs_domain_quota_ok - Check for domain's quota.
 *
 * @domain: Pointer to "struct ccs_domain_info".
 *
 * Returns true if the domain is not exceeded quota, false otherwise.
 */
bool ccs_domain_quota_ok(struct ccs_domain_info * const domain)
{
        unsigned int count = 0;
        struct ccs_acl_info *ptr;
        bool quota_ok = false;
        if (!domain)
                return true;
        /***** READER SECTION START *****/
        down_read(&ccs_policy_lock);
        list_for_each_entry(ptr, &domain->acl_info_list, list) {
                if (ptr->type & ACL_DELETED)
                        continue;
                switch (ptr->type) {
                        struct ccs_single_path_acl_record *acl1;
                        struct ccs_double_path_acl_record *acl2;
                        u16 perm;
                case TYPE_SINGLE_PATH_ACL:
                        acl1 = container_of(ptr,
                                            struct ccs_single_path_acl_record,
                                            head);
                        perm = acl1->perm;
                        if (perm & (1 << TYPE_EXECUTE_ACL))
                                count++;
                        if (perm &
                            ((1 << TYPE_READ_ACL) | (1 << TYPE_WRITE_ACL)))
                                count++;
                        if (perm & (1 << TYPE_CREATE_ACL))
                                count++;
                        if (perm & (1 << TYPE_UNLINK_ACL))
                                count++;
                        if (perm & (1 << TYPE_MKDIR_ACL))
                                count++;
                        if (perm & (1 << TYPE_RMDIR_ACL))
                                count++;
                        if (perm & (1 << TYPE_MKFIFO_ACL))
                                count++;
                        if (perm & (1 << TYPE_MKSOCK_ACL))
                                count++;
                        if (perm & (1 << TYPE_MKBLOCK_ACL))
                                count++;
                        if (perm & (1 << TYPE_MKCHAR_ACL))
                                count++;
                        if (perm & (1 << TYPE_TRUNCATE_ACL))
                                count++;
                        if (perm & (1 << TYPE_SYMLINK_ACL))
                                count++;
                        if (perm & (1 << TYPE_REWRITE_ACL))
                                count++;
                        break;
                case TYPE_DOUBLE_PATH_ACL:
                        acl2 = container_of(ptr,
                                            struct ccs_double_path_acl_record,
                                            head);
                        perm = acl2->perm;
                        if (perm & (1 << TYPE_LINK_ACL))
                                count++;
                        if (perm & (1 << TYPE_RENAME_ACL))
                                count++;
                        break;
                case TYPE_EXECUTE_HANDLER:
                case TYPE_DENIED_EXECUTE_HANDLER:
                        break;
                default:
                        count++;
                }
        }
        if (count < ccs_check_flags(domain, CCS_MAX_ACCEPT_ENTRY))
                quota_ok = true;
        else 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);
        }
        up_read(&ccs_policy_lock);
        /***** READER SECTION END *****/
        return quota_ok;
}

/**
 * ccs_find_or_assign_new_profile - Create a new profile.
 *
 * @profile: Profile number to create.
 *
 * Returns pointer to "struct ccs_profile" on success, NULL otherwise.
 */
static struct ccs_profile *ccs_find_or_assign_new_profile(const unsigned int
                                                          profile)
{
        struct ccs_profile *ptr;
        struct ccs_profile *entry;
        int i;
        if (profile >= MAX_PROFILES)
                return NULL;
        entry = kzalloc(sizeof(*entry), GFP_KERNEL);
        /***** WRITER SECTION START *****/
        down_write(&ccs_policy_lock);
        ptr = ccs_profile_ptr[profile];
        if (!ptr && ccs_memory_ok(entry)) {
                ptr = entry;
                for (i = 0; i < CCS_MAX_CONTROL_INDEX; i++)
                        ptr->value[i] = ccs_control_array[i].current_value;
                /*
                 * Needn't to initialize "ptr->capability_value"
                 * because they are always 0.
                 */
                mb(); /* Avoid out-of-order execution. */
                ccs_profile_ptr[profile] = ptr;
                entry = NULL;
        }
        up_write(&ccs_policy_lock);
        /***** WRITER SECTION END *****/
        kfree(entry);
        return ptr;
}

/**
 * ccs_write_profile - Write profile table.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int ccs_write_profile(struct ccs_io_buffer *head)
{
        char *data = head->write_buf;
        unsigned int i;
        unsigned int value;
        char *cp;
        struct ccs_profile *ccs_profile;
        i = simple_strtoul(data, &cp, 10);
        if (data != cp) {
                if (*cp != '-')
                        return -EINVAL;
                data = cp + 1;
        }
        ccs_profile = ccs_find_or_assign_new_profile(i);
        if (!ccs_profile)
                return -EINVAL;
        cp = strchr(data, '=');
        if (!cp)
                return -EINVAL;
        *cp = '\0';
        ccs_update_counter(CCS_UPDATES_COUNTER_PROFILE);
        if (!strcmp(data, "COMMENT")) {
                ccs_profile->comment = ccs_get_name(cp + 1);
                ccs_profile_entry_used[0] = true;
                return 0;
        }
#ifdef CONFIG_TOMOYO
        if (ccs_str_starts(&data, KEYWORD_MAC_FOR_CAPABILITY)) {
                if (sscanf(cp + 1, "%u", &value) != 1) {
                        for (i = 0; i < 4; i++) {
                                if (strcmp(cp + 1, ccs_mode_4[i]))
                                        continue;
                                value = i;
                                break;
                        }
                        if (i == 4)
                                return -EINVAL;
                }
                if (value > 3)
                        value = 3;
                for (i = 0; i < CCS_MAX_CAPABILITY_INDEX; i++) {
                        if (strcmp(data, ccs_capability_control_keyword[i]))
                                continue;
                        ccs_profile->capability_value[i] = value;
                        ccs_profile_entry_used[i + 1 + CCS_MAX_CONTROL_INDEX]
                                = true;
                        return 0;
                }
                return -EINVAL;
        }
#endif
        for (i = 0; i < CCS_MAX_CONTROL_INDEX; i++) {
                if (strcmp(data, ccs_control_array[i].keyword))
                        continue;
                if (sscanf(cp + 1, "%u", &value) != 1) {
                        int j;
                        const char **modes;
                        switch (i) {
                        case CCS_RESTRICT_AUTOBIND:
                        case CCS_VERBOSE:
                                modes = ccs_mode_2;
                                break;
                        default:
                                modes = ccs_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 > ccs_control_array[i].max_value) {
                        value = ccs_control_array[i].max_value;
                }
                switch (i) {
                case CCS_DENY_CONCEAL_MOUNT:
                case CCS_RESTRICT_UNMOUNT:
                        if (value == 1)
                                value = 2; /* learning mode is not supported. */
                }
                ccs_profile->value[i] = value;
                ccs_profile_entry_used[i + 1] = true;
                return 0;
        }
        return -EINVAL;
}

/**
 * ccs_read_profile - Read profile table.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 *
 * Returns 0.
 */
static int ccs_read_profile(struct ccs_io_buffer *head)
{
        static const int ccs_total
                = CCS_MAX_CONTROL_INDEX + CCS_MAX_CAPABILITY_INDEX + 1;
        int step;
        if (head->read_eof)
                return 0;
        for (step = head->read_step; step < MAX_PROFILES * ccs_total; step++) {
                const u8 index = step / ccs_total;
                u8 type = step % ccs_total;
                const struct ccs_profile *ccs_profile = ccs_profile_ptr[index];
                head->read_step = step;
                if (!ccs_profile)
                        continue;
#if !defined(CONFIG_SAKURA) || !defined(CONFIG_TOMOYO)
                switch (type - 1) {
#ifndef CONFIG_SAKURA
                case CCS_DENY_CONCEAL_MOUNT:
                case CCS_RESTRICT_CHROOT:
                case CCS_RESTRICT_MOUNT:
                case CCS_RESTRICT_UNMOUNT:
                case CCS_RESTRICT_PIVOT_ROOT:
                case CCS_RESTRICT_AUTOBIND:
#endif
#ifndef CONFIG_TOMOYO
                case CCS_MAC_FOR_FILE:
                case CCS_MAC_FOR_IOCTL:
                case CCS_MAC_FOR_ARGV0:
                case CCS_MAC_FOR_ENV:
                case CCS_MAC_FOR_NETWORK:
                case CCS_MAC_FOR_SIGNAL:
                case CCS_MAX_ACCEPT_ENTRY:
                case CCS_VERBOSE:
#endif
                        continue;
                }
#endif
                if (!ccs_profile_entry_used[type])
                        continue;
                if (!type) { /* Print profile' comment tag. */
                        if (!ccs_io_printf(head, "%u-COMMENT=%s\n",
                                           index, ccs_profile->comment ?
                                           ccs_profile->comment->name : ""))
                                break;
                        continue;
                }
                type--;
                if (type >= CCS_MAX_CONTROL_INDEX) {
#ifdef CONFIG_TOMOYO
                        const int i = type - CCS_MAX_CONTROL_INDEX;
                        const u8 value = ccs_profile->capability_value[i];
                        if (!ccs_io_printf(head,
                                           "%u-" KEYWORD_MAC_FOR_CAPABILITY
                                           "%s=%s\n", index,
                                           ccs_capability_control_keyword[i],
                                           ccs_mode_4[value]))
                                break;
#endif
                } else {
                        const unsigned int value = ccs_profile->value[type];
                        const char **modes = NULL;
                        const char *keyword = ccs_control_array[type].keyword;
                        switch (ccs_control_array[type].max_value) {
                        case 3:
                                modes = ccs_mode_4;
                                break;
                        case 1:
                                modes = ccs_mode_2;
                                break;
                        }
                        if (modes) {
                                if (!ccs_io_printf(head, "%u-%s=%s\n", index,
                                                   keyword, modes[value]))
                                        break;
                        } else {
                                if (!ccs_io_printf(head, "%u-%s=%u\n", index,
                                                   keyword, value))
                                        break;
                        }
                }
        }
        if (step == MAX_PROFILES * ccs_total)
                head->read_eof = true;
        return 0;
}

/* The list for "struct ccs_policy_manager_entry". */
LIST_HEAD(ccs_policy_manager_list);

/**
 * ccs_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.
 */
static int ccs_update_manager_entry(const char *manager, const bool is_delete)
{
        struct ccs_policy_manager_entry *entry = NULL;
        struct ccs_policy_manager_entry *ptr;
        const struct ccs_path_info *saved_manager;
        int error = is_delete ? -ENOENT : -ENOMEM;
        bool is_domain = false;
        if (ccs_is_domain_def(manager)) {
                if (!ccs_is_correct_domain(manager, __func__))
                        return -EINVAL;
                is_domain = true;
        } else {
                if (!ccs_is_correct_path(manager, 1, -1, -1, __func__))
                        return -EINVAL;
        }
        saved_manager = ccs_get_name(manager);
        if (!saved_manager)
                return -ENOMEM;
        if (!is_delete)
                entry = kzalloc(sizeof(*entry), GFP_KERNEL);
        /***** WRITER SECTION START *****/
        down_write(&ccs_policy_lock);
        list_for_each_entry(ptr, &ccs_policy_manager_list, list) {
                if (ptr->manager != saved_manager)
                        continue;
                ptr->is_deleted = is_delete;
                error = 0;
                break;
        }
        if (!is_delete && error && ccs_memory_ok(entry)) {
                entry->manager = saved_manager;
                saved_manager = NULL;
                entry->is_domain = is_domain;
                list_add_tail(&entry->list, &ccs_policy_manager_list);
                entry = NULL;
                error = 0;
        }
        up_write(&ccs_policy_lock);
        /***** WRITER SECTION END *****/
        ccs_put_name(saved_manager);
        kfree(entry);
        if (!error)
                ccs_update_counter(CCS_UPDATES_COUNTER_MANAGER);
        return error;
}

/**
 * ccs_write_manager_policy - Write manager policy.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int ccs_write_manager_policy(struct ccs_io_buffer *head)
{
        char *data = head->write_buf;
        bool is_delete = ccs_str_starts(&data, KEYWORD_DELETE);
        if (!strcmp(data, "manage_by_non_root")) {
                ccs_manage_by_non_root = !is_delete;
                return 0;
        }
        return ccs_update_manager_entry(data, is_delete);
}

/**
 * ccs_read_manager_policy - Read manager policy.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 *
 * Returns 0.
 */
static int ccs_read_manager_policy(struct ccs_io_buffer *head)
{
        struct list_head *pos;
        bool done = true;
        if (head->read_eof)
                return 0;
        /***** READER SECTION START *****/
        down_read(&ccs_policy_lock);
        list_for_each_cookie(pos, head->read_var2.u.list,
                              &ccs_policy_manager_list) {
                struct ccs_policy_manager_entry *ptr;
                ptr = list_entry(pos, struct ccs_policy_manager_entry, list);
                if (ptr->is_deleted)
                        continue;
                done = ccs_io_printf(head, "%s\n", ptr->manager->name);
                if (!done)
                        break;
        }
        up_read(&ccs_policy_lock);
        /***** READER SECTION END *****/
        head->read_eof = done;
        return 0;
}

/**
 * ccs_is_policy_manager - Check whether the current process is a policy manager.
 *
 * Returns true if the current process is permitted to modify policy
 * via /proc/ccs/ interface.
 */
static bool ccs_is_policy_manager(void)
{
        struct ccs_policy_manager_entry *ptr;
        const char *exe;
        struct task_struct *task = current;
        const struct ccs_path_info *domainname
                = ccs_current_domain()->domainname;
        bool found = false;
        if (!ccs_policy_loaded)
                return true;
        if (task->ccs_flags & CCS_TASK_IS_POLICY_MANAGER)
                return true;
        if (!ccs_manage_by_non_root && (current_uid() || current_euid()))
                return false;
        list_for_each_entry(ptr, &ccs_policy_manager_list, list) {
                if (!ptr->is_deleted && ptr->is_domain
                    && !ccs_pathcmp(domainname, ptr->manager)) {
                        /* Set manager flag. */
                        task->ccs_flags |= CCS_TASK_IS_POLICY_MANAGER;
                        return true;
                }
        }
        exe = ccs_get_exe();
        if (!exe)
                return false;
        list_for_each_entry(ptr, &ccs_policy_manager_list, list) {
                if (!ptr->is_deleted && !ptr->is_domain
                    && !strcmp(exe, ptr->manager->name)) {
                        found = true;
                        /* Set manager flag. */
                        task->ccs_flags |= CCS_TASK_IS_POLICY_MANAGER;
                        break;
                }
        }
        if (!found) { /* Reduce error messages. */
                static pid_t ccs_last_pid;
                const pid_t pid = current->pid;
                if (ccs_last_pid != pid) {
                        printk(KERN_WARNING "%s ( %s ) is not permitted to "
                               "update policies.\n", domainname->name, exe);
                        ccs_last_pid = pid;
                }
        }
        ccs_free(exe);
        return found;
}

#ifdef CONFIG_TOMOYO

/**
 * ccs_find_condition_part - Find condition part from the statement.
 *
 * @data: String to parse.
 *
 * Returns pointer to the condition part if it was found in the statement,
 * NULL otherwise.
 */
static char *ccs_find_condition_part(char *data)
{
        char *cp = strstr(data, " if ");
        if (cp) {
                while (1) {
                        char *cp2 = strstr(cp + 3, " if ");
                        if (!cp2)
                                break;
                        cp = cp2;
                }
                *cp++ = '\0';
        } else {
                cp = strstr(data, " ; set ");
                if (cp)
                        *cp++ = '\0';
        }
        return cp;
}

/**
 * ccs_is_select_one - Parse select command.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 * @data: String to parse.
 *
 * Returns true on success, false otherwise.
 */
static bool ccs_is_select_one(struct ccs_io_buffer *head, const char *data)
{
        unsigned int pid;
        struct ccs_cookie *cookie = &head->write_var1;
        if (!strcmp(data, "allow_execute")) {
                head->read_execute_only = true;
                return true;
        }
        if (sscanf(data, "pid=%u", &pid) == 1) {
                struct task_struct *p;
                cookie->u.domain = NULL;
                /***** READER SECTION START *****/
                down_read(&ccs_policy_lock);
                /***** CRITICAL SECTION START *****/
                read_lock(&tasklist_lock);
                p = find_task_by_pid(pid);
                if (p)
                        cookie->u.domain = ccs_task_domain(p);
                read_unlock(&tasklist_lock);
                /***** CRITICAL SECTION END *****/
                up_read(&ccs_policy_lock);
                /***** READER SECTION END *****/
        } else if (!strncmp(data, "domain=", 7)) {
                cookie->u.domain = NULL;
                if (ccs_is_domain_def(data + 7))
                        ccs_find_domain(data + 7, cookie);
        } else
                return false;
        /* Accessing read_buf is safe because head->io_sem is held. */
        if (!head->read_buf)
                return true; /* Do nothing if open(O_WRONLY). */
        /***** READER SECTION START *****/
        down_read(&ccs_policy_lock);
        if (cookie->u.domain)
                head->read_var1.u.list = cookie->u.domain->list.prev;
        up_read(&ccs_policy_lock);
        /***** READER SECTION END *****/
        head->read_avail = 0;
        ccs_io_printf(head, "# select %s\n", data);
        head->read_single_domain = true;
        head->read_eof = !cookie->u.domain;
        head->read_var2.u.list = NULL;
        head->read_bit = 0;
        head->read_step = 0;
        if (cookie->u.domain && cookie->u.domain->is_deleted)
                ccs_io_printf(head, "# This is a deleted domain.\n");
        return true;
}

/**
 * ccs_write_domain_policy - Write domain policy.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int ccs_write_domain_policy(struct ccs_io_buffer *head)
{
        char *data = head->write_buf;
        struct ccs_cookie *cookie = &head->write_var1;
        bool is_delete = false;
        bool is_select = false;
        unsigned int profile;
        const struct ccs_condition_list *cond = NULL;
        char *cp;
        if (ccs_str_starts(&data, KEYWORD_DELETE))
                is_delete = true;
        else if (ccs_str_starts(&data, KEYWORD_SELECT))
                is_select = true;
        if (is_select && ccs_is_select_one(head, data))
                return 0;
        /* Don't allow updating policies by non manager programs. */
        if (!ccs_is_policy_manager())
                return -EPERM;
        if (ccs_is_domain_def(data)) {
                cookie->u.domain = NULL;
                if (is_delete) {
                        ccs_delete_domain(data);
                } else if (is_select)
                        ccs_find_domain(data, cookie);
                else
                        ccs_find_or_assign_new_domain(data, 0, cookie);
                ccs_update_counter(CCS_UPDATES_COUNTER_DOMAIN_POLICY);
                return 0;
        }
        if (!cookie->u.domain)
                return -EINVAL;

        if (sscanf(data, KEYWORD_USE_PROFILE "%u", &profile) == 1
            && profile < MAX_PROFILES) {
                if (ccs_profile_ptr[profile] || !ccs_policy_loaded)
                        cookie->u.domain->profile = (u8) profile;
                return 0;
        }
        if (!strcmp(data, KEYWORD_IGNORE_GLOBAL_ALLOW_READ)) {
                cookie->u.domain->ignore_global_allow_read = !is_delete;
                return 0;
        }
        if (!strcmp(data, KEYWORD_IGNORE_GLOBAL_ALLOW_ENV)) {
                cookie->u.domain->ignore_global_allow_env = !is_delete;
                return 0;
        }
        cp = ccs_find_condition_part(data);
        if (cp) {
                cond = ccs_find_or_assign_new_condition(cp);
                if (!cond)
                        return -EINVAL;
        }
        if (ccs_str_starts(&data, KEYWORD_ALLOW_CAPABILITY))
                return ccs_write_capability_policy(data, cookie->u.domain,
                                                   cond, is_delete);
        else if (ccs_str_starts(&data, KEYWORD_ALLOW_NETWORK))
                return ccs_write_network_policy(data, cookie->u.domain, cond,
                                                is_delete);
        else if (ccs_str_starts(&data, KEYWORD_ALLOW_SIGNAL))
                return ccs_write_signal_policy(data, cookie->u.domain, cond,
                                               is_delete);
        else if (ccs_str_starts(&data, KEYWORD_ALLOW_ARGV0))
                return ccs_write_argv0_policy(data, cookie->u.domain, cond,
                                              is_delete);
        else if (ccs_str_starts(&data, KEYWORD_ALLOW_ENV))
                return ccs_write_env_policy(data, cookie->u.domain, cond,
                                            is_delete);
        else if (ccs_str_starts(&data, KEYWORD_ALLOW_IOCTL))
                return ccs_write_ioctl_policy(data, cookie->u.domain, cond,
                                              is_delete);
        else
                return ccs_write_file_policy(data, cookie->u.domain, cond,
                                             is_delete);
}

/**
 * ccs_print_single_path_acl - Print a single path ACL entry.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 * @ptr:  Pointer to "struct ccs_single_path_acl_record".
 * @cond: Pointer to "struct ccs_condition_list". May be NULL.
 *
 * Returns true on success, false otherwise.
 */
static bool ccs_print_single_path_acl(struct ccs_io_buffer *head,
                                      struct ccs_single_path_acl_record *ptr,
                                      const struct ccs_condition_list *cond)
{
        int pos;
        u8 bit;
        const char *atmark = "";
        const char *filename;
        const u16 perm = ptr->perm;
        if (ptr->u_is_group) {
                atmark = "@";
                filename = ptr->u.group->group_name->name;
        } else {
                filename = ptr->u.filename->name;
        }
        for (bit = head->read_bit; bit < MAX_SINGLE_PATH_OPERATION; bit++) {
                const char *msg;
                if (!(perm & (1 << bit)))
                        continue;
                if (head->read_execute_only && bit != TYPE_EXECUTE_ACL)
                        continue;
                /* Print "read/write" instead of "read" and "write". */
                if ((bit == TYPE_READ_ACL || bit == TYPE_WRITE_ACL)
                    && (perm & (1 << TYPE_READ_WRITE_ACL)))
                        continue;
                msg = ccs_sp2keyword(bit);
                pos = head->read_avail;
                if (!ccs_io_printf(head, "allow_%s %s%s", msg,
                                   atmark, filename) ||
                    !ccs_print_condition(head, cond))
                        goto out;
        }
        head->read_bit = 0;
        return true;
 out:
        head->read_bit = bit;
        head->read_avail = pos;
        return false;
}

/**
 * ccs_print_double_path_acl - Print a double path ACL entry.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 * @ptr:  Pointer to "struct ccs_double_path_acl_record".
 * @cond: Pointer to "struct ccs_condition_list". May be NULL.
 *
 * Returns true on success, false otherwise.
 */
static bool ccs_print_double_path_acl(struct ccs_io_buffer *head,
                                      struct ccs_double_path_acl_record *ptr,
                                      const struct ccs_condition_list *cond)
{
        int pos;
        const char *atmark1 = "";
        const char *atmark2 = "";
        const char *filename1;
        const char *filename2;
        const u8 perm = ptr->perm;
        u8 bit;
        if (ptr->u1_is_group) {
                atmark1 = "@";
                filename1 = ptr->u1.group1->group_name->name;
        } else {
                filename1 = ptr->u1.filename1->name;
        }
        if (ptr->u2_is_group) {
                atmark2 = "@";
                filename2 = ptr->u2.group2->group_name->name;
        } else {
                filename2 = ptr->u2.filename2->name;
        }
        for (bit = head->read_bit; bit < MAX_DOUBLE_PATH_OPERATION; bit++) {
                const char *msg;
                if (!(perm & (1 << bit)))
                        continue;
                msg = ccs_dp2keyword(bit);
                pos = head->read_avail;
                if (!ccs_io_printf(head, "allow_%s %s%s %s%s", msg,
                                   atmark1, filename1, atmark2, filename2) ||
                    !ccs_print_condition(head, cond))
                        goto out;
        }
        head->read_bit = 0;
        return true;
 out:
        head->read_bit = bit;
        head->read_avail = pos;
        return false;
}

/**
 * ccs_print_ioctl_acl - Print an ioctl ACL entry.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 * @ptr:  Pointer to "struct ccs_ioctl_acl_record".
 * @cond: Pointer to "struct ccs_condition_list". May be NULL.
 *
 * Returns true on success, false otherwise.
 */
static bool ccs_print_ioctl_acl(struct ccs_io_buffer *head,
                                struct ccs_ioctl_acl_record *ptr,
                                const struct ccs_condition_list *cond)
{
        int pos = head->read_avail;
        const char *atmark = "";
        const char *filename;
        const unsigned int cmd_min = ptr->cmd_min;
        const unsigned int cmd_max = ptr->cmd_max;
        if (ptr->u_is_group) {
                atmark = "@";
                filename = ptr->u.group->group_name->name;
        } else {
                filename = ptr->u.filename->name;
        }
        if (!ccs_io_printf(head, KEYWORD_ALLOW_IOCTL "%s%s ", atmark, filename))
                goto out;
        if (!ccs_io_printf(head, "%u", cmd_min))
                goto out;
        if (cmd_min != cmd_max && !ccs_io_printf(head, "-%u", cmd_max))
                goto out;
        if (!ccs_print_condition(head, cond))
                goto out;
        return true;
 out:
        head->read_avail = pos;
        return false;
}

/**
 * ccs_print_argv0_acl - Print an argv[0] ACL entry.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 * @ptr:  Pointer to "struct ccs_argv0_acl_record".
 * @cond: Pointer to "struct ccs_condition_list". May be NULL.
 *
 * Returns true on success, false otherwise.
 */
static bool ccs_print_argv0_acl(struct ccs_io_buffer *head,
                                struct ccs_argv0_acl_record *ptr,
                                const struct ccs_condition_list *cond)
{
        int pos = head->read_avail;
        if (!ccs_io_printf(head, KEYWORD_ALLOW_ARGV0 "%s %s",
                           ptr->filename->name, ptr->argv0->name))
                goto out;
        if (!ccs_print_condition(head, cond))
                goto out;
        return true;
 out:
        head->read_avail = pos;
        return false;
}

/**
 * ccs_print_env_acl - Print an evironment variable name's ACL entry.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 * @ptr:  Pointer to "struct ccs_env_acl_record".
 * @cond: Pointer to "struct ccs_condition_list". May be NULL.
 *
 * Returns true on success, false otherwise.
 */
static bool ccs_print_env_acl(struct ccs_io_buffer *head,
                              struct ccs_env_acl_record *ptr,
                              const struct ccs_condition_list *cond)
{
        int pos = head->read_avail;
        if (!ccs_io_printf(head, KEYWORD_ALLOW_ENV "%s", ptr->env->name))
                goto out;
        if (!ccs_print_condition(head, cond))
                goto out;
        return true;
 out:
        head->read_avail = pos;
        return false;
}

/**
 * ccs_print_capability_acl - Print a capability ACL entry.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 * @ptr:  Pointer to "struct ccs_capability_acl_record".
 * @cond: Pointer to "struct ccs_condition_list". May be NULL.
 *
 * Returns true on success, false otherwise.
 */
static bool ccs_print_capability_acl(struct ccs_io_buffer *head,
                                     struct ccs_capability_acl_record *ptr,
                                     const struct ccs_condition_list *cond)
{
        int pos = head->read_avail;
        if (!ccs_io_printf(head, KEYWORD_ALLOW_CAPABILITY "%s",
                           ccs_cap2keyword(ptr->operation)))
                goto out;
        if (!ccs_print_condition(head, cond))
                goto out;
        return true;
 out:
        head->read_avail = pos;
        return false;
}

/**
 * ccs_print_ipv4_entry - Print IPv4 address of a network ACL entry.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 * @ptr:  Pointer to "struct ccs_ip_network_acl_record".
 *
 * Returns true on success, false otherwise.
 */
static bool ccs_print_ipv4_entry(struct ccs_io_buffer *head,
                                 struct ccs_ip_network_acl_record *ptr)
{
        const u32 min_address = ptr->u.ipv4.min;
        const u32 max_address = ptr->u.ipv4.max;
        if (!ccs_io_printf(head, "%u.%u.%u.%u", HIPQUAD(min_address)))
                return false;
        if (min_address != max_address
            && !ccs_io_printf(head, "-%u.%u.%u.%u", HIPQUAD(max_address)))
                return false;
        return true;
}

/**
 * ccs_print_ipv6_entry - Print IPv6 address of a network ACL entry.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 * @ptr:  Pointer to "struct ccs_ip_network_acl_record".
 *
 * Returns true on success, false otherwise.
 */
static bool ccs_print_ipv6_entry(struct ccs_io_buffer *head,
                                 struct ccs_ip_network_acl_record *ptr)
{
        char buf[64];
        const struct in6_addr *min_address = ptr->u.ipv6.min;
        const struct in6_addr *max_address = ptr->u.ipv6.max;
        ccs_print_ipv6(buf, sizeof(buf), min_address);
        if (!ccs_io_printf(head, "%s", buf))
                return false;
        if (min_address != max_address) {
                ccs_print_ipv6(buf, sizeof(buf), max_address);
                if (!ccs_io_printf(head, "-%s", buf))
                        return false;
        }
        return true;
}

/**
 * ccs_print_port_entry - Print port number of a network ACL entry.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 * @ptr:  Pointer to "struct ccs_ip_network_acl_record".
 *
 * Returns true on success, false otherwise.
 */
static bool ccs_print_port_entry(struct ccs_io_buffer *head,
                                 struct ccs_ip_network_acl_record *ptr)
{
        const u16 min_port = ptr->min_port;
        const u16 max_port = ptr->max_port;
        if (!ccs_io_printf(head, " %u", min_port))
                return false;
        if (min_port != max_port && !ccs_io_printf(head, "-%u", max_port))
                return false;
        return true;
}

/**
 * ccs_print_network_acl - Print a network ACL entry.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 * @ptr:  Pointer to "struct ccs_ip_network_acl_record".
 * @cond: Pointer to "struct ccs_condition_list". May be NULL.
 *
 * Returns true on success, false otherwise.
 */
static bool ccs_print_network_acl(struct ccs_io_buffer *head,
                                  struct ccs_ip_network_acl_record *ptr,
                                  const struct ccs_condition_list *cond)
{
        int pos = head->read_avail;
        if (!ccs_io_printf(head, KEYWORD_ALLOW_NETWORK "%s ",
                           ccs_net2keyword(ptr->operation_type)))
                goto out;
        switch (ptr->record_type) {
        case IP_RECORD_TYPE_ADDRESS_GROUP:
                if (!ccs_io_printf(head, "@%s", ptr->u.group->group_name->name))
                        goto out;
                break;
        case IP_RECORD_TYPE_IPv4:
                if (!ccs_print_ipv4_entry(head, ptr))
                        goto out;
                break;
        case IP_RECORD_TYPE_IPv6:
                if (!ccs_print_ipv6_entry(head, ptr))
                        goto out;
                break;
        }
        if (!ccs_print_port_entry(head, ptr))
                goto out;
        if (!ccs_print_condition(head, cond))
                goto out;
        return true;
 out:
        head->read_avail = pos;
        return false;
}

/**
 * ccs_print_signal_acl - Print a signal ACL entry.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 * @ptr:  Pointer to "struct signale_acl_record".
 * @cond: Pointer to "struct ccs_condition_list". May be NULL.
 *
 * Returns true on success, false otherwise.
 */
static bool ccs_print_signal_acl(struct ccs_io_buffer *head,
                                 struct ccs_signal_acl_record *ptr,
                                 const struct ccs_condition_list *cond)
{
        int pos = head->read_avail;
        if (!ccs_io_printf(head, KEYWORD_ALLOW_SIGNAL "%u %s",
                           ptr->sig, ptr->domainname->name))
                goto out;
        if (!ccs_print_condition(head, cond))
                goto out;
        return true;
 out:
        head->read_avail = pos;
        return false;
}

/**
 * ccs_print_execute_handler_record - Print an execute handler ACL entry.
 *
 * @head:    Pointer to "struct ccs_io_buffer".
 * @keyword: Name of the keyword.
 * @ptr:     Pointer to "struct ccs_execute_handler_record".
 *
 * Returns true on success, false otherwise.
 */
static bool ccs_print_execute_handler_record(struct ccs_io_buffer *head,
                                             const char *keyword,
                                             struct ccs_execute_handler_record *
                                             ptr)
{
        return ccs_io_printf(head, "%s %s\n", keyword, ptr->handler->name);
}

/**
 * ccs_print_entry - Print an ACL entry.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 * @ptr:  Pointer to an ACL entry.
 *
 * Returns true on success, false otherwise.
 */
static bool ccs_print_entry(struct ccs_io_buffer *head,
                            struct ccs_acl_info *ptr)
{
        const struct ccs_condition_list *cond = ptr->cond;
        const u8 acl_type = ptr->type;
        if (acl_type & ACL_DELETED)
                return true;
        if (acl_type == TYPE_SINGLE_PATH_ACL) {
                struct ccs_single_path_acl_record *acl
                        = container_of(ptr, struct ccs_single_path_acl_record,
                                       head);
                return ccs_print_single_path_acl(head, acl, cond);
        }
        if (acl_type == TYPE_EXECUTE_HANDLER) {
                struct ccs_execute_handler_record *acl
                        = container_of(ptr, struct ccs_execute_handler_record,
                                       head);
                const char *keyword = KEYWORD_EXECUTE_HANDLER;
                return ccs_print_execute_handler_record(head, keyword, acl);
        }
        if (acl_type == TYPE_DENIED_EXECUTE_HANDLER) {
                struct ccs_execute_handler_record *acl
                        = container_of(ptr, struct ccs_execute_handler_record,
                                       head);
                const char *keyword = KEYWORD_DENIED_EXECUTE_HANDLER;
                return ccs_print_execute_handler_record(head, keyword, acl);
        }
        if (head->read_execute_only)
                return true;
        if (acl_type == TYPE_DOUBLE_PATH_ACL) {
                struct ccs_double_path_acl_record *acl
                        = container_of(ptr, struct ccs_double_path_acl_record,
                                       head);
                return ccs_print_double_path_acl(head, acl, cond);
        }
        if (acl_type == TYPE_IOCTL_ACL) {
                struct ccs_ioctl_acl_record *acl
                        = container_of(ptr, struct ccs_ioctl_acl_record, head);
                return ccs_print_ioctl_acl(head, acl, cond);
        }
        if (acl_type == TYPE_ARGV0_ACL) {
                struct ccs_argv0_acl_record *acl
                        = container_of(ptr, struct ccs_argv0_acl_record, head);
                return ccs_print_argv0_acl(head, acl, cond);
        }
        if (acl_type == TYPE_ENV_ACL) {
                struct ccs_env_acl_record *acl
                        = container_of(ptr, struct ccs_env_acl_record, head);
                return ccs_print_env_acl(head, acl, cond);
        }
        if (acl_type == TYPE_CAPABILITY_ACL) {
                struct ccs_capability_acl_record *acl
                        = container_of(ptr, struct ccs_capability_acl_record,
                                       head);
                return ccs_print_capability_acl(head, acl, cond);
        }
        if (acl_type == TYPE_IP_NETWORK_ACL) {
                struct ccs_ip_network_acl_record *acl
                        = container_of(ptr, struct ccs_ip_network_acl_record,
                                       head);
                return ccs_print_network_acl(head, acl, cond);
        }
        if (acl_type == TYPE_SIGNAL_ACL) {
                struct ccs_signal_acl_record *acl
                        = container_of(ptr, struct ccs_signal_acl_record, head);
                return ccs_print_signal_acl(head, acl, cond);
        }
        /* Workaround for gcc 3.2.2's inline bug. */
        if (acl_type & ACL_DELETED)
                return true;
        BUG(); /* This must not happen. */
        return false;
}

/**
 * ccs_read_domain_policy - Read domain policy.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 *
 * Returns 0.
 */
static int ccs_read_domain_policy(struct ccs_io_buffer *head)
{
        struct list_head *dpos;
        struct list_head *apos;
        if (head->read_eof)
                return 0;
        if (head->read_step == 0)
                head->read_step = 1;
        list_for_each_cookie(dpos, head->read_var1.u.list, &ccs_domain_list) {
                struct ccs_domain_info *domain;
                const char *quota_exceeded = "";
                const char *transition_failed = "";
                const char *ignore_global_allow_read = "";
                const char *ignore_global_allow_env = "";
                domain = list_entry(dpos, struct ccs_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->domain_transition_failed)
                        transition_failed = "transition_failed\n";
                if (domain->ignore_global_allow_read)
                        ignore_global_allow_read
                                = KEYWORD_IGNORE_GLOBAL_ALLOW_READ "\n";
                if (domain->ignore_global_allow_env)
                        ignore_global_allow_env
                                = KEYWORD_IGNORE_GLOBAL_ALLOW_ENV "\n";
                if (!ccs_io_printf(head, "%s\n" KEYWORD_USE_PROFILE "%u\n"
                                   "%s%s%s%s\n", domain->domainname->name,
                                   domain->profile, quota_exceeded,
                                   transition_failed,
                                   ignore_global_allow_read,
                                   ignore_global_allow_env))
                        return 0;
                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.u.list,
                                      &domain->acl_info_list) {
                        struct ccs_acl_info *ptr
                                = list_entry(apos, struct ccs_acl_info, list);
                        if (!ccs_print_entry(head, ptr))
                                return 0;
                }
                head->read_step = 3;
 tail_mark:
                if (!ccs_io_printf(head, "\n"))
                        return 0;
                head->read_step = 1;
                if (head->read_single_domain)
                        break;
        }
        head->read_eof = true;
        return 0;
}

#endif

/**
 * ccs_write_domain_profile - Assign profile for specified domain.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 *
 * Returns 0 on success, -EINVAL otherwise.
 */
static int ccs_write_domain_profile(struct ccs_io_buffer *head)
{
        char *data = head->write_buf;
        char *cp = strchr(data, ' ');
        struct ccs_cookie cookie;
        unsigned int profile;
        if (!cp)
                return -EINVAL;
        *cp = '\0';
        profile = simple_strtoul(data, NULL, 10);
        if (profile >= MAX_PROFILES)
                return -EINVAL;
        ccs_add_cookie(&cookie, NULL);
        if (ccs_find_domain(cp + 1, &cookie) &&
            (ccs_profile_ptr[profile] || !ccs_policy_loaded))
                cookie.u.domain->profile = (u8) profile;
        ccs_del_cookie(&cookie);
        ccs_update_counter(CCS_UPDATES_COUNTER_DOMAIN_POLICY);
        return 0;
}

/**
 * ccs_read_domain_profile - Read only domainname and profile.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 *
 * Returns list of profile number and domainname pairs.
 */
static int ccs_read_domain_profile(struct ccs_io_buffer *head)
{
        struct list_head *pos;
        if (head->read_eof)
                return 0;
        list_for_each_cookie(pos, head->read_var1.u.list, &ccs_domain_list) {
                struct ccs_domain_info *domain;
                domain = list_entry(pos, struct ccs_domain_info, list);
                if (domain->is_deleted)
                        continue;
                if (!ccs_io_printf(head, "%u %s\n", domain->profile,
                                   domain->domainname->name))
                        return 0;
        }
        head->read_eof = true;
        return 0;
}

/**
 * ccs_write_pid: Specify PID to obtain domainname.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 *
 * Returns 0.
 */
static int ccs_write_pid(struct ccs_io_buffer *head)
{
        head->read_eof = false;
        return 0;
}

/**
 * ccs_read_pid - Read information of a process.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 *
 * Returns the domainname which the specified PID is in or
 * process information of the specified PID on success,
 * empty string otherwise.
 */
static int ccs_read_pid(struct ccs_io_buffer *head)
{
        char *buf = head->write_buf;
        bool task_info = false;
        unsigned int pid;
        struct task_struct *p;
        struct ccs_domain_info *domain = NULL;
        u32 ccs_flags = 0;
        /* Accessing write_buf is safe because head->io_sem is held. */
        if (!buf)
                goto done; /* Do nothing if open(O_RDONLY). */
        if (head->read_avail || head->read_eof)
                goto done;
        head->read_eof = true;
        if (ccs_str_starts(&buf, "info "))
                task_info = true;
        pid = (unsigned int) simple_strtoul(buf, NULL, 10);
        /***** READER SECTION START *****/
        down_read(&ccs_policy_lock);
   