Re: [Qemu-devel] [PATCH] vnc: disable VNC password authentication (security type 2) when in FIPS mode

[Andreas Färber]

Am 01.05.2012 23:20, schrieb Paul Moore:
> FIPS 140-2 requires disabling certain ciphers, including DES, which is used
> by VNC to obscure passwords when they are sent over the network.  The
> solution for FIPS users is to disable the use of VNC password auth when the
> host system is operating in FIPS mode.
> 
> This patch causes qemu to emits a syslog entry indicating that VNC password

"to emit"

> auth is disabled when it detects the host is running in FIPS mode, and
> unless a VNC password was specified on the command line it continues
> normally.  However, if a VNC password was given on the command line, qemu
> fails with an error message to stderr explaining that that VNC password

"explaining that VNC"

> auth is not allowed in FIPS mode.
> 
> Signed-off-by: Paul Moore <address@hidden>

Interesting feature. :)

> diff --git a/ui/vnc.c b/ui/vnc.c
> index deb9ecd..620791e 100644
> --- a/ui/vnc.c
> +++ b/ui/vnc.c
> @@ -32,6 +32,7 @@
>  #include "acl.h"
>  #include "qemu-objects.h"
>  #include "qmp-commands.h"
> +#include <syslog.h>

syslog.h is POSIX, but it'll need a guard for mingw32.

> @@ -48,6 +49,24 @@ static DisplayChangeListener *dcl;
>  static int vnc_cursor_define(VncState *vs);
>  static void vnc_release_modifiers(VncState *vs);
>  
> +static int fips_enabled(void)
> +{
> +    int enabled = 0;
> +    char value;
> +    FILE *fds;
> +
> +    fds = fopen("/proc/sys/crypto/fips_enabled", "r");

How standardized is this? Should we limit this to __linux__ or something?

> +    if (fds == NULL) {
> +        return 0;
> +    }
> +    if (fread(&value, sizeof(value), 1, fds) == 1 && value == '1') {
> +        enabled = 1;
> +    }
> +    fclose(fds);
> +
> +    return enabled;
> +}

bool would seem nicer as return type and field type below.

Andreas

> +
>  static void vnc_set_share_mode(VncState *vs, VncShareMode mode)
>  {
>  #ifdef _VNC_DEBUG

> diff --git a/ui/vnc.h b/ui/vnc.h
> index a851ebd..8746a98 100644
> --- a/ui/vnc.h
> +++ b/ui/vnc.h
> @@ -160,6 +160,7 @@ struct VncDisplay
>      char *display;
>      char *password;
>      time_t expires;
> +    int fips;
>      int auth;
>      bool lossy;
>      bool non_adaptive;

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