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Fix detection of getrandom()

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Manuel Pégourié-Gonnard 2015-04-29 14:03:28 +02:00
parent f5203e0bb5
commit d97828e7af
2 changed files with 52 additions and 16 deletions
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2
ChangeLog
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@ -28,6 +28,8 @@ Features
errors on use of deprecated functions. errors on use of deprecated functions.
Bugfix Bugfix
* Fix detection of support for getrandom() on Linux (reported by syzzer) by
doing it at runtime (using uname) rather that compile time.
* Fix handling of symlinks by "make install" (found by Gaël PORTAY). * Fix handling of symlinks by "make install" (found by Gaël PORTAY).
* Fix potential NULL pointer dereference (not trigerrable remotely) when * Fix potential NULL pointer dereference (not trigerrable remotely) when
ssl_write() is called before the handshake is finished (introduced in ssl_write() is called before the handshake is finished (introduced in

66
library/entropy_poll.c
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@ -86,27 +86,46 @@ static int getrandom_wrapper( void *buf, size_t buflen, unsigned int flags )
{ {
return( syscall( SYS_getrandom, buf, buflen, flags ) ); return( syscall( SYS_getrandom, buf, buflen, flags ) );
} }
#endif /* SYS_getrandom */
#endif /* __linux__ */
#if defined(HAVE_GETRANDOM) #include <sys/utsname.h>
/* Check if version is at least 3.17.0 */
#include <errno.h> static int check_version_3_17_plus( void )
int platform_entropy_poll( void *data,
unsigned char *output, size_t len, size_t *olen )
{ {
int ret; int minor;
((void) data); struct utsname un;
const char *ver;
if( ( ret = getrandom_wrapper( output, len, 0 ) ) < 0 ) /* Get version information */
return( POLARSSL_ERR_ENTROPY_SOURCE_FAILED ); uname(&un);
ver = un.release;
/* Check major version; assume a single digit */
if( ver[0] < '3' || ver[0] > '9' || ver [1] != '.' )
return( -1 );
if( ver[0] - '0' > 3 )
return( 0 );
/* Ok, so now we know major == 3, check minor.
* Assume 1 or 2 digits. */
if( ver[2] < '0' || ver[2] > '9' )
return( -1 );
minor = ver[2] - '0';
if( ver[3] >= '0' && ver[3] <= '9' )
minor = 10 * minor + ver[3] - '0';
else if( ver [3] != '.' )
return( -1 );
if( minor < 17 )
return( -1 );
*olen = ret;
return( 0 ); return( 0 );
} }
static int has_getrandom = -1;
#else /* HAVE_GETRANDOM */ #endif /* SYS_getrandom */
#endif /* __linux__ */
#include <stdio.h> #include <stdio.h>
@ -117,6 +136,22 @@ int platform_entropy_poll( void *data,
size_t ret; size_t ret;
((void) data); ((void) data);
#if defined(HAVE_GETRANDOM)
if( has_getrandom == -1 )
has_getrandom = ( check_version_3_17_plus() == 0 );
if( has_getrandom )
{
int ret;
if( ( ret = getrandom_wrapper( output, len, 0 ) ) < 0 )
return( POLARSSL_ERR_ENTROPY_SOURCE_FAILED );
*olen = ret;
return( 0 );
}
#endif /* HAVE_GETRANDOM */
*olen = 0; *olen = 0;
file = fopen( "/dev/urandom", "rb" ); file = fopen( "/dev/urandom", "rb" );
@ -135,7 +170,6 @@ int platform_entropy_poll( void *data,
return( 0 ); return( 0 );
} }
#endif /* HAVE_GETRANDOM */
#endif /* _WIN32 && !EFIX64 && !EFI32 */ #endif /* _WIN32 && !EFIX64 && !EFI32 */
#endif /* !POLARSSL_NO_PLATFORM_ENTROPY */ #endif /* !POLARSSL_NO_PLATFORM_ENTROPY */