ntdll: Randomize security cookie when available (try 4)

[André Hentschel]

Am 29.06.2015 um 14:16 schrieb Alexandre Julliard:
> André Hentschel <nerv at dawncrow.de> writes:
> 
>> @@ -1278,6 +1281,26 @@ static NTSTATUS map_image( HANDLE hmapping, int fd, char *base, SIZE_T total_siz
>>          }
>>      }
>>  
>> +
>> +    /* randomize security cookie */
>> +
>> +    if (IMAGE_DIRECTORY_ENTRY_LOAD_CONFIG < nt->OptionalHeader.NumberOfRvaAndSizes &&
>> +        (pos = nt->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_LOAD_CONFIG].VirtualAddress))
>> +    {
>> +        IMAGE_LOAD_CONFIG_DIRECTORY *loadcfg = (IMAGE_LOAD_CONFIG_DIRECTORY *)(ptr + pos);
>> +        ULONG_PTR *cookie = (ULONG_PTR *)loadcfg->SecurityCookie;
>> +        struct timeval tv;
>> +
>> +        gettimeofday( &tv, NULL );
>> +        srand( tv.tv_usec * getpid() );
>> +        *cookie = rand();
> 
> That's not much better. It doesn't make sense to reset the seed on every
> call.
> 

Where would you see the best point for srand()?
__wine_process_init()?
Should i do it with a "once" variable?
Or would you prefer something like in SystemFunction036 using /dev/urandom (suggested by Bruno)?