[mythtv] [PATCH] security update for realtime priority

[Matt Zimmerman]

Thanks for putting this together.

On Tue, Nov 02, 2004 at 05:01:04PM -0500, Doug Larrick wrote:

> +    // Create priveleged thread, then drop privs.  Keep this first to

"privileged"

> -    int status = pthread_create(&priv_thread, NULL, run_priv_thread, NULL);
> +    // create a capabilities mask that's nothing except CAP_SYS_NICE
> +    cap_t cap = cap_init();
> +    cap_value_t cval = CAP_SYS_NICE;
> +    int status = cap_set_flag(cap, CAP_PERMITTED, 1, &cval, CAP_SET);
> +    if (status < 0)
> +        perror("cap_set_flag (1)");
> +    status = cap_set_flag(cap, CAP_EFFECTIVE, 1, &cval, CAP_SET);
> +    if (status < 0)
> +        perror("cap_set_flag (2)");
> +    // silently fail cap_set_proc; we'll get a good message later if not SUID
> +    status = cap_set_proc(cap);
> +    // thread will be created with CAP_SYS_NICE
> +    status = pthread_create(&priv_thread, NULL, run_priv_thread, NULL);

Won't this produce a lot of error messages if myth is not running as root?
We should continue to support that configuration.

> +    // Drop back to real user
>      setuid(getuid());
> +    // get rid of even CAP_SYS_NICE for the rest of execution
> +    status = cap_clear(cap);
> +    if (status < 0)
> +        perror("cap_clear");
> +    status = cap_set_proc(cap);
> +    if (status < 0)
> +        perror("cap_set_proc (2)");    
> +    status = cap_free(cap);
> +    if (status < 0)
> +        perror("cap_free");
> +
> +    QApplication a(argc, argv);
> +
> +    gContext = new MythContext(MYTH_BINARY_VERSION);

Likewise here.

-- 
 - mdz