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openssl/crypto/rand/rand_unix.c

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/*
* 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
*/
#define _GNU_SOURCE
#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(__linux)
# include <sys/syscall.h>
#endif
#if defined(__FreeBSD__)
# include <sys/types.h>
# include <sys/sysctl.h>
# include <sys/param.h>
#endif
#if defined(__OpenBSD__)
# include <sys/param.h>
#endif
#ifdef OPENSSL_SYS_UNIX
# include <sys/types.h>
# include <unistd.h>
# include <sys/time.h>
static uint64_t get_time_stamp(void);
static uint64_t get_timer_bits(void);
/* Macro to convert two thirty two bit values into a sixty four bit one */
# define TWO32TO64(a, b) ((((uint64_t)(a)) << 32) + (b))
/*
* Check for the existence and support of POSIX timers. The standard
* says that the _POSIX_TIMERS macro will have a positive value if they
* are available.
*
* However, we want an additional constraint: that the timer support does
* not require an extra library dependency. Early versions of glibc
* require -lrt to be specified on the link line to access the timers,
* so this needs to be checked for.
*
* It is worse because some libraries define __GLIBC__ but don't
* support the version testing macro (e.g. uClibc). This means
* an extra check is needed.
*
* The final condition is:
* "have posix timers and either not glibc or glibc without -lrt"
*
* The nested #if sequences are required to avoid using a parameterised
* macro that might be undefined.
*/
# undef OSSL_POSIX_TIMER_OKAY
# if defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0
# if defined(__GLIBC__)
# if defined(__GLIBC_PREREQ)
# if __GLIBC_PREREQ(2, 17)
# define OSSL_POSIX_TIMER_OKAY
# endif
# endif
# else
# define OSSL_POSIX_TIMER_OKAY
# endif
# endif
#endif
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"
#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;
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
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(__GLIBC__) && defined(__GLIBC_PREREQ)
# if __GLIBC_PREREQ(2, 25)
# define OPENSSL_HAVE_GETRANDOM
# endif
# endif
# if (defined(__FreeBSD__) && __FreeBSD_version >= 1200061)
# define OPENSSL_HAVE_GETRANDOM
# endif
# if defined(OPENSSL_HAVE_GETRANDOM)
# include <sys/random.h>
# endif
# if defined(OPENSSL_RAND_SEED_OS)
# if !defined(DEVRANDOM)
# error "OS seeding requires DEVRANDOM to be configured"
# endif
# define OPENSSL_RAND_SEED_GETRANDOM
# define OPENSSL_RAND_SEED_DEVRANDOM
# endif
# if defined(OPENSSL_RAND_SEED_LIBRANDOM)
# error "librandom not (yet) supported"
# endif
# if defined(__FreeBSD__) && defined(KERN_ARND)
/*
* sysctl_random(): Use sysctl() to read a random number from the kernel
* Returns the size on success, 0 on failure.
*/
static size_t sysctl_random(char *buf, size_t buflen)
{
int mib[2];
size_t done = 0;
size_t len;
/*
* 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;
mib[0] = CTL_KERN;
mib[1] = KERN_ARND;
do {
len = buflen;
if (sysctl(mib, 2, buf, &len, NULL, 0) == -1)
return done;
done += len;
buf += len;
buflen -= len;
} while (buflen > 0);
return done;
}
# endif
/*
* syscall_random(): Try to get random data using a system call
* returns the number of bytes returned in buf, or <= 0 on error.
*/
int syscall_random(void *buf, size_t buflen)
{
# if defined(OPENSSL_HAVE_GETRANDOM)
return (int)getrandom(buf, buflen, 0);
# endif
# if defined(__linux) && defined(SYS_getrandom)
return (int)syscall(SYS_getrandom, buf, buflen, 0);
# endif
# if defined(__FreeBSD__) && defined(KERN_ARND)
return (int)sysctl_random(buf, buflen);
# endif
/* Supported since OpenBSD 5.6 */
# if defined(__OpenBSD__) && OpenBSD >= 201411
return getentropy(buf, buflen);
# endif
return -1;
}
/*
* 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 (syscall_random(buffer, bytes_needed) == (int)bytes_needed)
bytes = bytes_needed;
rand_pool_add_end(pool, bytes, 8 * bytes);
entropy_available = rand_pool_entropy_available(pool);
}
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;
rand_pool_add_end(pool, bytes, 8 * bytes);
entropy_available = rand_pool_entropy_available(pool);
}
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;
rand_pool_add_end(pool, bytes, 8 * bytes);
entropy_available = rand_pool_entropy_available(pool);
}
if (entropy_available > 0)
return entropy_available;
}
}
# endif
return rand_pool_entropy_available(pool);
# endif
}
# endif
#endif
#ifdef OPENSSL_SYS_UNIX
int rand_pool_add_nonce_data(RAND_POOL *pool)
{
struct {
pid_t pid;
CRYPTO_THREAD_ID tid;
uint64_t time;
} data = { 0 };
/*
* Add process id, thread id, and a high resolution timestamp to
* ensure that the nonce is unique whith high probability for
* different process instances.
*/
data.pid = getpid();
data.tid = CRYPTO_THREAD_get_current_id();
data.time = get_time_stamp();
return rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0);
}
int rand_pool_add_additional_data(RAND_POOL *pool)
{
struct {
CRYPTO_THREAD_ID tid;
uint64_t time;
} data = { 0 };
/*
* Add some noise from the thread id and a high resolution timer.
* The thread id adds a little randomness if the drbg is accessed
* concurrently (which is the case for the <master> drbg).
*/
data.tid = CRYPTO_THREAD_get_current_id();
data.time = get_timer_bits();
return rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0);
}
/*
* Get the current time with the highest possible resolution
*
* The time stamp is added to the nonce, so it is optimized for not repeating.
* The current time is ideal for this purpose, provided the computer's clock
* is synchronized.
*/
static uint64_t get_time_stamp(void)
{
# if defined(OSSL_POSIX_TIMER_OKAY)
{
struct timespec ts;
if (clock_gettime(CLOCK_REALTIME, &ts) == 0)
return TWO32TO64(ts.tv_sec, ts.tv_nsec);
}
# endif
# if defined(__unix__) \
|| (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
{
struct timeval tv;
if (gettimeofday(&tv, NULL) == 0)
return TWO32TO64(tv.tv_sec, tv.tv_usec);
}
# endif
return time(NULL);
}
/*
* Get an arbitrary timer value of the highest possible resolution
*
* The timer value is added as random noise to the additional data,
* which is not considered a trusted entropy sourec, so any result
* is acceptable.
*/
static uint64_t get_timer_bits(void)
{
uint64_t res = OPENSSL_rdtsc();
if (res != 0)
return res;
# if defined(__sun) || defined(__hpux)
return gethrtime();
# elif defined(_AIX)
{
timebasestruct_t t;
read_wall_time(&t, TIMEBASE_SZ);
return TWO32TO64(t.tb_high, t.tb_low);
}
# elif defined(OSSL_POSIX_TIMER_OKAY)
{
struct timespec ts;
# ifdef CLOCK_BOOTTIME
# define CLOCK_TYPE CLOCK_BOOTTIME
# elif defined(_POSIX_MONOTONIC_CLOCK)
# define CLOCK_TYPE CLOCK_MONOTONIC
# else
# define CLOCK_TYPE CLOCK_REALTIME
# endif
if (clock_gettime(CLOCK_TYPE, &ts) == 0)
return TWO32TO64(ts.tv_sec, ts.tv_nsec);
}
# endif
# if defined(__unix__) \
|| (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
{
struct timeval tv;
if (gettimeofday(&tv, NULL) == 0)
return TWO32TO64(tv.tv_sec, tv.tv_usec);
}
# endif
return time(NULL);
}
#endif
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