/*

 *  Platform-specific and custom entropy polling functions

 *

 *  Copyright The Mbed TLS Contributors

 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later

 */

#if defined(__linux__) || defined(__midipix__)

/* Ensure that syscall() is available even when compiling with -std=c99 */

#if !defined(_GNU_SOURCE)

#define _GNU_SOURCE

#endif

#endif

#include "common.h"

#include <string.h>

#if defined(MBEDTLS_ENTROPY_C)

#include "mbedtls/entropy.h"

#include "entropy_poll.h"

#include "mbedtls/error.h"

#if defined(MBEDTLS_TIMING_C)

#include "mbedtls/timing.h"

#endif

#include "mbedtls/platform.h"

#if !defined(MBEDTLS_NO_PLATFORM_ENTROPY)

#if !defined(unix) && !defined(__unix__) && !defined(__unix) && \

    !defined(__APPLE__) && !defined(_WIN32) && !defined(__QNXNTO__) && \

    !defined(__HAIKU__) && !defined(__midipix__) && !defined(__MVS__)

#error \

    "Platform entropy sources only work on Unix and Windows, see MBEDTLS_NO_PLATFORM_ENTROPY in mbedtls_config.h"

#endif

#if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)

#include <windows.h>

#include <bcrypt.h>

#include <intsafe.h>

int mbedtls_platform_entropy_poll(void *data, unsigned char *output, size_t len,

                                  size_t *olen)

{

    ((void) data);

    *olen = 0;

    /*

     * BCryptGenRandom takes ULONG for size, which is smaller than size_t on

     * 64-bit Windows platforms. Extract entropy in chunks of len (dependent

     * on ULONG_MAX) size.

     */

    while (len != 0) {

        unsigned long ulong_bytes =

            (len > ULONG_MAX) ? ULONG_MAX : (unsigned long) len;

        if (!BCRYPT_SUCCESS(BCryptGenRandom(NULL, output, ulong_bytes,

                                            BCRYPT_USE_SYSTEM_PREFERRED_RNG))) {

            return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;

        }

        *olen += ulong_bytes;

        len -= ulong_bytes;

    }

    return 0;

}

#else /* _WIN32 && !EFIX64 && !EFI32 */

/*

 * Test for Linux getrandom() support.

 * Since there is no wrapper in the libc yet, use the generic syscall wrapper

 * available in GNU libc and compatible libc's (eg uClibc).

 */

#if ((defined(__linux__) && defined(__GLIBC__)) || defined(__midipix__))

#include <unistd.h>

#include <sys/syscall.h>

#if defined(SYS_getrandom)

#define HAVE_GETRANDOM

#include <errno.h>

static int getrandom_wrapper(void *buf, size_t buflen, unsigned int flags)

{

    /* MemSan cannot understand that the syscall writes to the buffer */

#if defined(__has_feature)

#if __has_feature(memory_sanitizer)

    memset(buf, 0, buflen);

#endif

#endif

    return (int) syscall(SYS_getrandom, buf, buflen, flags);

}

#endif /* SYS_getrandom */

#endif /* __linux__ || __midipix__ */

#if defined(__FreeBSD__) || defined(__DragonFly__)

#include <sys/param.h>

#if (defined(__FreeBSD__) && __FreeBSD_version >= 1200000) || \

    (defined(__DragonFly__) && __DragonFly_version >= 500700)

#include <errno.h>

#include <sys/random.h>

#define HAVE_GETRANDOM

static int getrandom_wrapper(void *buf, size_t buflen, unsigned int flags)

{

    return (int) getrandom(buf, buflen, flags);

}

#endif /* (__FreeBSD__ && __FreeBSD_version >= 1200000) ||

          (__DragonFly__ && __DragonFly_version >= 500700) */

#endif /* __FreeBSD__ || __DragonFly__ */

/*

 * Some BSD systems provide KERN_ARND.

 * This is equivalent to reading from /dev/urandom, only it doesn't require an

 * open file descriptor, and provides up to 256 bytes per call (basically the

 * same as getentropy(), but with a longer history).

 *

 * Documentation: https://netbsd.gw.com/cgi-bin/man-cgi?sysctl+7

 */

#if (defined(__FreeBSD__) || defined(__NetBSD__)) && !defined(HAVE_GETRANDOM)

#include <sys/param.h>

#include <sys/sysctl.h>

#if defined(KERN_ARND)

#define HAVE_SYSCTL_ARND

static int sysctl_arnd_wrapper(unsigned char *buf, size_t buflen)

{

    int name[2];

    size_t len;

    name[0] = CTL_KERN;

    name[1] = KERN_ARND;

    while (buflen > 0) {

        len = buflen > 256 ? 256 : buflen;

        if (sysctl(name, 2, buf, &len, NULL, 0) == -1) {

            return -1;

        }

        buflen -= len;

        buf += len;

    }

    return 0;

}

#endif /* KERN_ARND */

#endif /* __FreeBSD__ || __NetBSD__ */

#include <stdio.h>

int mbedtls_platform_entropy_poll(void *data,

                                  unsigned char *output, size_t len, size_t *olen)

{

    FILE *file;

    size_t read_len;

    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    ((void) data);

#if defined(HAVE_GETRANDOM)

    ret = getrandom_wrapper(output, len, 0);

    if (ret >= 0) {

        *olen = (size_t) ret;

        return 0;

    } else if (errno != ENOSYS) {

        return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;

    }

    /* Fall through if the system call isn't known. */

#else

    ((void) ret);

#endif /* HAVE_GETRANDOM */

#if defined(HAVE_SYSCTL_ARND)

    ((void) file);

    ((void) read_len);

    if (sysctl_arnd_wrapper(output, len) == -1) {

        return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;

    }

    *olen = len;

    return 0;

#else

    *olen = 0;

    file = fopen("/dev/urandom", "rb");

    if (file == NULL) {

        return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;

    }

    /* Ensure no stdio buffering of secrets, as such buffers cannot be wiped. */

    mbedtls_setbuf(file, NULL);

    read_len = fread(output, 1, len, file);

    if (read_len != len) {

        fclose(file);

        return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;

    }

    fclose(file);

    *olen = len;

    return 0;

#endif /* HAVE_SYSCTL_ARND */

}

#endif /* _WIN32 && !EFIX64 && !EFI32 */

#endif /* !MBEDTLS_NO_PLATFORM_ENTROPY */

#if defined(MBEDTLS_ENTROPY_NV_SEED)

int mbedtls_nv_seed_poll(void *data,

                         unsigned char *output, size_t len, size_t *olen)

{

    unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];

    size_t use_len = MBEDTLS_ENTROPY_BLOCK_SIZE;

    ((void) data);

    memset(buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE);

    if (mbedtls_nv_seed_read(buf, MBEDTLS_ENTROPY_BLOCK_SIZE) < 0) {

        return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;

    }

    if (len < use_len) {

        use_len = len;

    }

    memcpy(output, buf, use_len);

    *olen = use_len;

    return 0;

}

#endif /* MBEDTLS_ENTROPY_NV_SEED */

#endif /* MBEDTLS_ENTROPY_C */