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ui/vnc: Use gcrypto_random_bytes for start_auth_vnc

Use a better interface for random numbers than rand().
Fail gracefully if for some reason we cannot use the crypto system.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
tags/v4.1.0-rc0
Richard Henderson 6 months ago
parent
commit
f7b2502cdc
1 changed files with 11 additions and 11 deletions
  1. 11
    11
      ui/vnc.c

+ 11
- 11
ui/vnc.c View File

@@ -43,6 +43,7 @@
#include "crypto/hash.h"
#include "crypto/tlscredsanon.h"
#include "crypto/tlscredsx509.h"
#include "crypto/random.h"
#include "qom/object_interfaces.h"
#include "qemu/cutils.h"
#include "io/dns-resolver.h"
@@ -2547,16 +2548,6 @@ static void authentication_failed(VncState *vs)
vnc_client_error(vs);
}

static void make_challenge(VncState *vs)
{
int i;

srand(time(NULL)+getpid()+getpid()*987654+rand());

for (i = 0 ; i < sizeof(vs->challenge) ; i++)
vs->challenge[i] = (int) (256.0*rand()/(RAND_MAX+1.0));
}

static int protocol_client_auth_vnc(VncState *vs, uint8_t *data, size_t len)
{
unsigned char response[VNC_AUTH_CHALLENGE_SIZE];
@@ -2628,7 +2619,16 @@ reject:

void start_auth_vnc(VncState *vs)
{
make_challenge(vs);
Error *err = NULL;

if (qcrypto_random_bytes(vs->challenge, sizeof(vs->challenge), &err)) {
trace_vnc_auth_fail(vs, vs->auth, "cannot get random bytes",
error_get_pretty(err));
error_free(err);
authentication_failed(vs);
return;
}

/* Send client a 'random' challenge */
vnc_write(vs, vs->challenge, sizeof(vs->challenge));
vnc_flush(vs);

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