Commit 9b5f1c8f authored by Dr. Matthias St. Pierre's avatar Dr. Matthias St. Pierre
Browse files

rand_unix.c: assimilate syscall_random() with getrandom(2) 



Change return value type to ssize_t and ensure that a negative value
is returned only if a corresponding errno is set.

Reviewed-by: default avatarAndy Polyakov <appro@openssl.org>
Reviewed-by: default avatarPaul Dale <paul.dale@oracle.com>
Reviewed-by: default avatarTim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6990)
parent 8e5da579

crypto/rand/rand_unix.c

+37 −20
Original line number Diff line number Diff line
@@ -77,8 +77,6 @@ static uint64_t get_timer_bits(void); 
# endif

#endif /* defined(OPENSSL_SYS_UNIX) || defined(__DJGPP__) */



int syscall_random(void *buf, size_t buflen);



#if (defined(OPENSSL_SYS_VXWORKS) || defined(OPENSSL_SYS_UEFI)) && \

        !defined(OPENSSL_RAND_SEED_NONE)

# error "UEFI and VXWorks only support seeding NONE"
@@ -88,6 +86,8 @@ int syscall_random(void *buf, size_t buflen); 
    || defined(OPENSSL_SYS_VMS) || defined(OPENSSL_SYS_VXWORKS) \

    || defined(OPENSSL_SYS_UEFI))



static ssize_t syscall_random(void *buf, size_t buflen);



# if defined(OPENSSL_SYS_VOS)



#  ifndef OPENSSL_RAND_SEED_OS
@@ -192,22 +192,29 @@ void rand_pool_keep_random_devices_open(int keep) 
#  if (defined(__FreeBSD__) || defined(__NetBSD__)) && defined(KERN_ARND)

/*

 * sysctl_random(): Use sysctl() to read a random number from the kernel

 * Returns the size on success, 0 on failure.

 * Returns the number of bytes returned in buf on success, -1 on failure.

 */

static size_t sysctl_random(char *buf, size_t buflen)

static ssize_t sysctl_random(char *buf, size_t buflen)

{

    int mib[2];

    size_t done = 0;

    size_t len;



    /*

     * Note: sign conversion between size_t and ssize_t is safe even

     * without a range check, see comment in syscall_random()

     */



    /*

     * On FreeBSD old implementations returned longs, newer versions support

     * variable sizes up to 256 byte. The code below would not work properly

     * when the sysctl returns long and we want to request something not a

     * multiple of longs, which should never be the case.

     */

    if (!ossl_assert(buflen % sizeof(long) == 0))

        return 0;

    if (!ossl_assert(buflen % sizeof(long) == 0)) {

        errno = EINVAL;

        return -1;

    }



    /*

     * On NetBSD before 4.0 KERN_ARND was an alias for KERN_URND, and only
@@ -217,7 +224,8 @@ static size_t sysctl_random(char *buf, size_t buflen) 
     * Just return an error on older NetBSD versions.

     */

#if   defined(__NetBSD__) && __NetBSD_Version__ < 400000000

    return 0;

    errno = ENOSYS;

    return -1;

#endif



    mib[0] = CTL_KERN;
@@ -226,7 +234,7 @@ static size_t sysctl_random(char *buf, size_t buflen) 
    do {

        len = buflen;

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

            return done;

            return done > 0 ? done : -1;

        done += len;

        buf += len;

        buflen -= len;
@@ -238,10 +246,20 @@ static size_t sysctl_random(char *buf, size_t buflen) 


/*

 * syscall_random(): Try to get random data using a system call

 * returns the number of bytes returned in buf, or <= 0 on error.

 * returns the number of bytes returned in buf, or < 0 on error.

 */

int syscall_random(void *buf, size_t buflen)

static ssize_t syscall_random(void *buf, size_t buflen)

{

    /*

     * Note: 'buflen' equals the size of the buffer which is used by the

     * get_entropy() callback of the RAND_DRBG. It is roughly bounded by

     *

     *   2 * DRBG_MINMAX_FACTOR * (RAND_DRBG_STRENGTH / 8) = 2^13

     *

     * which is way below the OSSL_SSIZE_MAX limit. Therefore sign conversion

     * between size_t and ssize_t is safe even without a range check.

     */



    /*

     * Do runtime detection to find getentropy().

     *
@@ -253,10 +271,10 @@ int syscall_random(void *buf, size_t buflen) 
     * - FreeBSD since 12.0 (1200061)

     */

#  if defined(__GNUC__) && __GNUC__>=2 && defined(__ELF__) && !defined(__hpux)

    extern int getentropy(void *bufer, size_t length) __attribute__((weak));

    extern int getentropy(void *buffer, size_t length) __attribute__((weak));



    if (getentropy != NULL)

        return getentropy(buf, buflen) == 0 ? buflen : 0;

        return getentropy(buf, buflen) == 0 ? (ssize_t)buflen : -1;

#  else

    union {

        void *p;
@@ -271,19 +289,18 @@ int syscall_random(void *buf, size_t buflen) 
    p_getentropy.p = DSO_global_lookup("getentropy");

    ERR_pop_to_mark();

    if (p_getentropy.p != NULL)

        return p_getentropy.f(buf, buflen) == 0 ? buflen : 0;

        return p_getentropy.f(buf, buflen) == 0 ? (ssize_t)buflen : -1;

#  endif



    /* Linux supports this since version 3.17 */

#  if defined(__linux) && defined(SYS_getrandom)

    return (int)syscall(SYS_getrandom, buf, buflen, 0);

#  endif



#  if (defined(__FreeBSD__) || defined(__NetBSD__)) && defined(KERN_ARND)

    return (int)sysctl_random(buf, buflen);

#  endif



    return syscall(SYS_getrandom, buf, buflen, 0);

#  elif (defined(__FreeBSD__) || defined(__NetBSD__)) && defined(KERN_ARND)

    return sysctl_random(buf, buflen);

#  else

    errno = ENOSYS;

    return -1;

#  endif

}



#if  !defined(OPENSSL_RAND_SEED_NONE) && defined(OPENSSL_RAND_SEED_DEVRANDOM)