rand_unix.c
/*
* Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include "e_os.h"
#include <stdio.h>
#include "internal/cryptlib.h"
#include <openssl/rand.h>
#include "rand_lcl.h"
#include "internal/rand_int.h"
#include <stdio.h>
#if (defined(OPENSSL_SYS_VXWORKS) || defined(OPENSSL_SYS_UEFI)) && \
!defined(OPENSSL_RAND_SEED_NONE)
# error "UEFI and VXWorks only support seeding NONE"
#endif
#if !(defined(OPENSSL_SYS_WINDOWS) || defined(OPENSSL_SYS_WIN32) \
|| defined(OPENSSL_SYS_VMS) || defined(OPENSSL_SYS_VXWORKS) \
|| defined(OPENSSL_SYS_UEFI))
# if defined(OPENSSL_SYS_VOS)
# ifndef OPENSSL_RAND_SEED_OS
# error "Unsupported seeding method configured; must be os"
# endif
# if defined(OPENSSL_SYS_VOS_HPPA) && defined(OPENSSL_SYS_VOS_IA32)
# error "Unsupported HP-PA and IA32 at the same time."
# endif
# if !defined(OPENSSL_SYS_VOS_HPPA) && !defined(OPENSSL_SYS_VOS_IA32)
# error "Must have one of HP-PA or IA32"
# endif
/*
* The following algorithm repeatedly samples the real-time clock (RTC) to
* generate a sequence of unpredictable data. The algorithm relies upon the
* uneven execution speed of the code (due to factors such as cache misses,
* interrupts, bus activity, and scheduling) and upon the rather large
* relative difference between the speed of the clock and the rate at which
* it can be read. If it is ported to an environment where execution speed
* is more constant or where the RTC ticks at a much slower rate, or the
* clock can be read with fewer instructions, it is likely that the results
* would be far more predictable. This should only be used for legacy
* platforms.
*
* As a precaution, we assume only 2 bits of entropy per byte.
*/
size_t rand_pool_acquire_entropy(RAND_POOL *pool)
{
short int code;
gid_t curr_gid;
pid_t curr_pid;
uid_t curr_uid;
int i, k;
size_t bytes_needed;
struct timespec ts;
unsigned char v;
# ifdef OPENSSL_SYS_VOS_HPPA
long duration;
extern void s$sleep(long *_duration, short int *_code);
# else
long long duration;
extern void s$sleep2(long long *_duration, short int *_code);
# endif
/*
* Seed with the gid, pid, and uid, to ensure *some* variation between
* different processes.
*/
curr_gid = getgid();
rand_pool_add(pool, &curr_gid, sizeof(curr_gid), 0);
curr_pid = getpid();
rand_pool_add(pool, &curr_pid, sizeof(curr_pid), 0);
curr_uid = getuid();
rand_pool_add(pool, &curr_uid, sizeof(curr_uid), 0);
bytes_needed = rand_pool_bytes_needed(pool, 2 /*entropy_per_byte*/);
for (i = 0; i < bytes_needed; i++) {
/*
* burn some cpu; hope for interrupts, cache collisions, bus
* interference, etc.
*/
for (k = 0; k < 99; k++)
ts.tv_nsec = random();
# ifdef OPENSSL_SYS_VOS_HPPA
/* sleep for 1/1024 of a second (976 us). */
duration = 1;
s$sleep(&duration, &code);
# else
/* sleep for 1/65536 of a second (15 us). */
duration = 1;
s$sleep2(&duration, &code);
# endif
/* Get wall clock time, take 8 bits. */
clock_gettime(CLOCK_REALTIME, &ts);
v = (unsigned char)(ts.tv_nsec & 0xFF);
rand_pool_add(pool, arg, &v, sizeof(v) , 2);
}
return rand_pool_entropy_available(pool);
}
# else
# if defined(OPENSSL_RAND_SEED_EGD) && \
(defined(OPENSSL_NO_EGD) || !defined(DEVRANDOM_EGD))
# error "Seeding uses EGD but EGD is turned off or no device given"
# endif
# if defined(OPENSSL_RAND_SEED_DEVRANDOM) && !defined(DEVRANDOM)
# error "Seeding uses urandom but DEVRANDOM is not configured"
# endif
# if defined(OPENSSL_RAND_SEED_OS)
# if !defined(DEVRANDOM)
# error "OS seeding requires DEVRANDOM to be configured"
# endif
# define OPENSSL_RAND_SEED_DEVRANDOM
# if defined(__GLIBC__) && defined(__GLIBC_PREREQ)
# if __GLIBC_PREREQ(2, 25)
# define OPENSSL_RAND_SEED_GETRANDOM
# endif
# endif
# endif
# ifdef OPENSSL_RAND_SEED_GETRANDOM
# include <sys/random.h>
# endif
# if defined(OPENSSL_RAND_SEED_LIBRANDOM)
# error "librandom not (yet) supported"
# endif
/*
* Try the various seeding methods in turn, exit when successful.
*
* TODO(DRBG): If more than one entropy source is available, is it
* preferable to stop as soon as enough entropy has been collected
* (as favored by @rsalz) or should one rather be defensive and add
* more entropy than requested and/or from different sources?
*
* Currently, the user can select multiple entropy sources in the
* configure step, yet in practice only the first available source
* will be used. A more flexible solution has been requested, but
* currently it is not clear how this can be achieved without
* overengineering the problem. There are many parameters which
* could be taken into account when selecting the order and amount
* of input from the different entropy sources (trust, quality,
* possibility of blocking).
*/
size_t rand_pool_acquire_entropy(RAND_POOL *pool)
{
# ifdef OPENSSL_RAND_SEED_NONE
return rand_pool_entropy_available(pool);
# else
size_t bytes_needed;
size_t entropy_available = 0;
unsigned char *buffer;
# ifdef OPENSSL_RAND_SEED_GETRANDOM
bytes_needed = rand_pool_bytes_needed(pool, 8 /*entropy_per_byte*/);
buffer = rand_pool_add_begin(pool, bytes_needed);
if (buffer != NULL) {
size_t bytes = 0;
if (getrandom(buffer, bytes_needed, 0) == (int)bytes_needed)
bytes = bytes_needed;
entropy_available = rand_pool_add_end(pool, bytes, 8 * bytes);
}
if (entropy_available > 0)
return entropy_available;
# endif
# if defined(OPENSSL_RAND_SEED_LIBRANDOM)
{
/* Not yet implemented. */
}
# endif
# ifdef OPENSSL_RAND_SEED_DEVRANDOM
bytes_needed = rand_pool_bytes_needed(pool, 8 /*entropy_per_byte*/);
if (bytes_needed > 0) {
static const char *paths[] = { DEVRANDOM, NULL };
FILE *fp;
int i;
for (i = 0; paths[i] != NULL; i++) {
if ((fp = fopen(paths[i], "rb")) == NULL)
continue;
setbuf(fp, NULL);
buffer = rand_pool_add_begin(pool, bytes_needed);
if (buffer != NULL) {
size_t bytes = 0;
if (fread(buffer, 1, bytes_needed, fp) == bytes_needed)
bytes = bytes_needed;
entropy_available = rand_pool_add_end(pool, bytes, 8 * bytes);
}
fclose(fp);
if (entropy_available > 0)
return entropy_available;
bytes_needed = rand_pool_bytes_needed(pool, 8 /*entropy_per_byte*/);
}
}
# endif
# ifdef OPENSSL_RAND_SEED_RDTSC
entropy_available = rand_acquire_entropy_from_tsc(pool);
if (entropy_available > 0)
return entropy_available;
# endif
# ifdef OPENSSL_RAND_SEED_RDCPU
entropy_available = rand_acquire_entropy_from_cpu(pool);
if (entropy_available > 0)
return entropy_available;
# endif
# ifdef OPENSSL_RAND_SEED_EGD
bytes_needed = rand_pool_bytes_needed(pool, 8 /*entropy_per_byte*/);
if (bytes_needed > 0) {
static const char *paths[] = { DEVRANDOM_EGD, NULL };
int i;
for (i = 0; paths[i] != NULL; i++) {
buffer = rand_pool_add_begin(pool, bytes_needed);
if (buffer != NULL) {
size_t bytes = 0;
int num = RAND_query_egd_bytes(paths[i],
buffer, (int)bytes_needed);
if (num == (int)bytes_needed)
bytes = bytes_needed;
entropy_available = rand_pool_add_end(pool, bytes, 8 * bytes);
}
if (entropy_available > 0)
return entropy_available;
}
}
# endif
return rand_pool_entropy_available(pool);
# endif
}
# endif
#endif
