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sysdep: Add wrapper to get random bytes - update

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Simplify the code and fix an issue with getentropy() return value.
This commit is contained in:
Ondrej Zajicek (work) 2021-04-08 01:15:17 +02:00
parent c48ebde5ce
commit e5724f71d2
4 changed files with 53 additions and 70 deletions
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1
conf/conf.c
View File

@ -524,7 +524,6 @@ order_shutdown(int gr)
c->gr_down = gr;
config_commit(c, RECONFIG_HARD, 0);
random_close();
shutting_down = 1;
}

1
configure.ac
View File

@ -376,7 +376,6 @@ fi
AC_CHECK_FUNCS(getrandom)
AC_CHECK_FUNCS(getentropy)
AC_CHECK_HEADERS(sys/random.h)
if test "$enable_debug" = yes ; then
AC_DEFINE([DEBUGGING], [1], [Define to 1 if debugging is enabled])

3
lib/birdlib.h
View File

@ -192,8 +192,7 @@ asm(
/* Pseudorandom numbers */
u32 random_u32(void);
int random_bytes(char *buf, size_t size);
void random_close(void);
void random_init(void);
void random_bytes(void *buf, size_t size);
#endif

118
sysdep/unix/random.c
View File

@ -8,23 +8,19 @@
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <errno.h>
#include "sysdep/config.h"
#ifdef HAVE_SYS_STAT_H
# include <sys/stat.h>
#endif
#ifdef HAVE_LINUX_RANDOM_H
# include <linux/random.h>
#endif
#if defined(HAVE_SYS_RANDOM_H) && (defined(HAVE_GETRANDOM) || defined(HAVE_GETENTROPY))
# include <sys/random.h>
#endif
#include "nest/bird.h"
#ifdef HAVE_GETRANDOM
#include <sys/random.h>
#endif
u32
random_u32(void)
{
@ -35,75 +31,65 @@ random_u32(void)
return (rand_low & 0xffff) | ((rand_high & 0xffff) << 16);
}
void
random_init()
{
char buf;
/* get a single random byte to trip any errors early */
random_bytes(&buf, sizeof(buf));
}
#if defined(HAVE_GETRANDOM) || defined(HAVE_GENTROPY)
int
random_bytes(char *buf, size_t size)
{
int n;
int flags = 0;
while (0 < size) {
#if defined(HAVE_GETRANDOM)
n = getrandom(buf, size, flags);
#else
n = getentropy(buf, size);
#endif
if (n < 0) {
if (errno == EINTR)
continue;
die("Couldn't get random bytes: %m");
}
buf += n;
size -= n;
}
return 0;
}
void random_close(void) {}
#else
/* If there is no getrandom() / getentropy(), use /dev/urandom */
#if !defined(HAVE_GETRANDOM) && !defined(HAVE_GETENTROPY)
#define HAVE_URANDOM_FD 1
static int urandom_fd = -1;
int random_bytes(char *buf, size_t size)
{
int n;
int
read_urandom_fd(void *buf, uint count)
{
if (urandom_fd < 0)
{
urandom_fd = open("/dev/urandom", O_RDONLY);
if (urandom_fd < 0)
die("Couldn't open /dev/urandom: %m");
die("Cannot open /dev/urandom: %m");
}
do
{
n = read(urandom_fd, buf, size);
if (n <= 0) {
if (errno == EINTR)
continue;
die("Couldn't read from /dev/urandom: %m");
}
buf += n;
size -= n;
} while (size > 0);
return read(urandom_fd, buf, count);
}
#endif
return 0;
void
random_init(void)
{
uint seed;
/* Get random bytes to trip any errors early and to seed random() */
random_bytes(&seed, sizeof(seed));
srandom(seed);
}
void
random_close(void)
random_bytes(void *buf, size_t count)
{
if (urandom_fd >= 0) {
close(urandom_fd);
urandom_fd = -1;
ASSERT(count <= 256);
while (count > 0)
{
int n = -1;
#if defined(HAVE_GETRANDOM)
n = getrandom(buf, count, 0);
#elif defined(HAVE_GETENTROPY)
n = getentropy(buf, count);
n = !n ? (int) count : n;
#elif defined(HAVE_URANDOM_FD)
n = read_urandom_fd(buf, count);
#endif
if (n < 0)
{
if (errno == EINTR)
continue;
die("Cannot get random bytes: %m");
}
buf += n;
count -= n;
}
}
#endif