libcryptoutil/common/random.c

	random.c revision 7b79d84636ec82b45f00c982cf6810db81852d17
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <locale.h>
#include <stdarg.h>
#include <cryptoutil.h>
#include <pthread.h>


static pthread_mutex_t  random_mutex = PTHREAD_MUTEX_INITIALIZER;
static pthread_mutex_t  urandom_mutex = PTHREAD_MUTEX_INITIALIZER;

static pthread_mutex_t  random_seed_mutex = PTHREAD_MUTEX_INITIALIZER;
static pthread_mutex_t  urandom_seed_mutex = PTHREAD_MUTEX_INITIALIZER;

#define RANDOM_DEVICE       "/dev/random"   /* random device name */
#define URANDOM_DEVICE      "/dev/urandom"  /* urandom device name */

static int  random_fd = -1;
static int  urandom_fd = -1;

static int  random_seed_fd = -1;
static int  urandom_seed_fd = -1;


/*
 * Equivalent of open(2) insulated from EINTR.
 * Also sets close-on-exec.
 */
int
open_nointr(const char *path, int oflag, ...)
{
    int fd;
    mode_t  pmode;
    va_list alist;

    va_start(alist, oflag);
    pmode = va_arg(alist, mode_t);
    va_end(alist);

    do {
        if ((fd = open(path, oflag, pmode)) >= 0) {
            (void) fcntl(fd, F_SETFD, FD_CLOEXEC);
            break;
        }
        /* errno definitely set by failed open() */
    } while (errno == EINTR);
    return (fd);
}

/*
 * Equivalent of read(2) insulated from EINTR.
 */
ssize_t
readn_nointr(int fd, void *dbuf, size_t dlen)
{
    char    *marker = dbuf;
    size_t  left = dlen;
    ssize_t nread = 0, err;

    for (err = 0; left > 0 && nread != -1; marker += nread, left -= nread) {
        if ((nread = read(fd, marker, left)) < 0) {
            if (errno == EINTR) {   /* keep trying */
                nread = 0;
                continue;
            }
            err = nread;        /* hard error */
            break;
        } else if (nread == 0) {
            break;
        }
    }
    return (err != 0 ? err : dlen - left);
}

/*
 * Equivalent of write(2) insulated from EINTR.
 */
ssize_t
writen_nointr(int fd, void *dbuf, size_t dlen)
{
    char    *marker = dbuf;
    size_t  left = dlen;
    ssize_t nwrite = 0, err;

    for (err = 0; left > 0 && nwrite != -1; marker += nwrite,
        left -= nwrite) {
        if ((nwrite = write(fd, marker, left)) < 0) {
            if (errno == EINTR) {   /* keep trying */
                nwrite = 0;
                continue;
            }
            err = nwrite;       /* hard error */
            break;
        } else if (nwrite == 0) {
            break;
        }
    }
    return (err != 0 ? err : dlen - left);
}

/*
 * Opens the random number generator devices if not already open.
 * Always returns the opened fd of the device, or error.
 */
static int
pkcs11_open_common(int *fd, pthread_mutex_t *mtx, const char *dev, int oflag)
{
    if (*fd < 0) {
        (void) pthread_mutex_lock(mtx);
        if (*fd < 0)
            *fd = open_nointr(dev, oflag);
        (void) pthread_mutex_unlock(mtx);
    }
    return (*fd);
}

static int
pkcs11_open_random(void)
{
    return (pkcs11_open_common(&random_fd, &random_mutex,
        RANDOM_DEVICE, O_RDONLY));
}

static int
pkcs11_open_urandom(void)
{
    return (pkcs11_open_common(&urandom_fd, &urandom_mutex,
        URANDOM_DEVICE, O_RDONLY));
}

static int
pkcs11_open_random_seed(void)
{
    return (pkcs11_open_common(&random_seed_fd, &random_seed_mutex,
        RANDOM_DEVICE, O_WRONLY));
}

static int
pkcs11_open_urandom_seed(void)
{
    return (pkcs11_open_common(&urandom_seed_fd, &urandom_seed_mutex,
        URANDOM_DEVICE, O_WRONLY));
}

/*
 * Close the random number generator devices if already open.
 */
static void
pkcs11_close_common(int *fd, pthread_mutex_t *mtx)
{
    if (*fd < 0)
        return;
    (void) pthread_mutex_lock(mtx);
    (void) close(*fd);
    *fd = -1;
    (void) pthread_mutex_unlock(mtx);
}

void
pkcs11_close_random(void)
{
    pkcs11_close_common(&random_fd, &random_mutex);
}

void
pkcs11_close_urandom(void)
{
    pkcs11_close_common(&urandom_fd, &urandom_mutex);
}

static void
pkcs11_close_random_seed(void)
{
    pkcs11_close_common(&random_seed_fd, &random_seed_mutex);
}

void
pkcs11_close_urandom_seed(void)
{
    pkcs11_close_common(&urandom_seed_fd, &urandom_seed_mutex);
}

/*
 * Seed /dev/random with the data in the buffer.
 */
int
pkcs11_seed_random(void *sbuf, size_t slen)
{
    if (sbuf == NULL || slen == 0)
        return (0);

    /* Seeding error could mean it's not supported (errno = EACCES) */
    if (pkcs11_open_random_seed() < 0)
        return (-1);

    if (writen_nointr(random_seed_fd, sbuf, slen) == slen) {
        pkcs11_close_random_seed();
        return (0);
    }
    return (-1);
}

/*
 * Seed /dev/urandom with the data in the buffer.
 */
int
pkcs11_seed_urandom(void *sbuf, size_t slen)
{
    if (sbuf == NULL || slen == 0)
        return (0);

    /* Seeding error could mean it's not supported (errno = EACCES) */
    if (pkcs11_open_urandom_seed() < 0)
        return (-1);

    if (writen_nointr(urandom_seed_fd, sbuf, slen) == slen) {
        pkcs11_close_urandom_seed();
        return (0);
    }
    return (-1);
}

/*
 * Put the requested amount of random data into a preallocated buffer.
 * Good for token key data, persistent objects.
 */
int
pkcs11_get_random(void *dbuf, size_t dlen)
{
    if (dbuf == NULL || dlen == 0)
        return (0);

    /* Read random data directly from /dev/random */
    if (pkcs11_open_random() < 0)
        return (-1);

    if (readn_nointr(random_fd, dbuf, dlen) == dlen)
        return (0);
    return (-1);
}

/*
 * Put the requested amount of random data into a preallocated buffer.
 * Good for passphrase salts, initialization vectors.
 */
int
pkcs11_get_urandom(void *dbuf, size_t dlen)
{
    if (dbuf == NULL || dlen == 0)
        return (0);

    /* Read random data directly from /dev/urandom */
    if (pkcs11_open_urandom() < 0)
        return (-1);

    if (readn_nointr(urandom_fd, dbuf, dlen) == dlen)
        return (0);
    return (-1);
}

/*
 * Same as pkcs11_get_urandom but ensures non zero data.
 */
int
pkcs11_get_nzero_urandom(void *dbuf, size_t dlen)
{
    char    extrarand[32];
    size_t  bytesleft = 0;
    size_t  i = 0;

    /* Start with some random data */
    if (pkcs11_get_urandom(dbuf, dlen) < 0)
        return (-1);

    /* Walk through data replacing any 0 bytes with more random data */
    while (i < dlen) {
        if (((char *)dbuf)[i] != 0) {
            i++;
            continue;
        }

        if (bytesleft == 0) {
            bytesleft = sizeof (extrarand);
            if (pkcs11_get_urandom(extrarand, bytesleft) < 0)
                return (-1);
        }
        bytesleft--;

        ((char *)dbuf)[i] = extrarand[bytesleft];
    }
    return (0);
}