Commit 38023b87 authored by Bernd Edlinger's avatar Bernd Edlinger
Browse files

Fix seeding from random device w/o getrandom syscall 



Use select to wait for /dev/random in readable state,
but do not actually read anything from /dev/random,
use /dev/urandom first.

Use linux define __NR_getrandom instead of the
glibc define SYS_getrandom, in case the kernel headers
are more current than the glibc headers.

Fixes #8215

Reviewed-by: default avatarKurt Roeckx <kurt@roeckx.be>
(Merged from https://github.com/openssl/openssl/pull/8251)
parent ed86f884

crypto/rand/rand_unix.c

+26 −3
Original line number Diff line number Diff line
@@ -19,7 +19,7 @@ 
#include <stdio.h>

#include "internal/dso.h"

#if defined(__linux)

# include <sys/syscall.h>

# include <asm/unistd.h>

#endif

#if defined(__FreeBSD__)

# include <sys/types.h>
@@ -324,8 +324,8 @@ static ssize_t syscall_random(void *buf, size_t buflen) 
#  endif



    /* Linux supports this since version 3.17 */

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

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

#  if defined(__linux) && defined(__NR_getrandom)

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

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

    return sysctl_random(buf, buflen);

#  else
@@ -510,6 +510,29 @@ size_t rand_pool_acquire_entropy(RAND_POOL *pool) 
    bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);

    {

        size_t i;

#ifdef DEVRANDOM_WAIT

        static int wait_done = 0;



        /*

         * On some implementations reading from /dev/urandom is possible

         * before it is initialized. Therefore we wait for /dev/random

         * to be readable to make sure /dev/urandom is initialized.

         */

        if (!wait_done && bytes_needed > 0) {

             int f = open(DEVRANDOM_WAIT, O_RDONLY);



             if (f >= 0) {

                 fd_set fds;



                 FD_ZERO(&fds);

                 FD_SET(f, &fds);

                 while (select(f+1, &fds, NULL, NULL, NULL) < 0

                        && errno == EINTR);

                 close(f);

             }

             wait_done = 1;

        }

#endif



        for (i = 0; bytes_needed > 0 && i < OSSL_NELEM(random_device_paths); i++) {

            ssize_t bytes = 0;

e_os.h

+3 −6
Original line number Diff line number Diff line
@@ -27,11 +27,8 @@ 
 * set this to a comma-separated list of 'random' device files to try out. By

 * default, we will try to read at least one of these files

 */

#  if defined(__s390__)

#   define DEVRANDOM "/dev/prandom","/dev/urandom","/dev/hwrng","/dev/random"

#  else

#   define DEVRANDOM "/dev/urandom","/dev/random","/dev/srandom"

#  endif

#  define DEVRANDOM "/dev/urandom", "/dev/random", "/dev/hwrng", "/dev/srandom"

#  define DEVRANDOM_WAIT "/dev/random"

# endif

# if !defined(OPENSSL_NO_EGD) && !defined(DEVRANDOM_EGD)

/*