Re: pgcrypto seeding problem when ssl=on

Noah Misch <noah@leadboat.com> writes:
> On Sat, Dec 22, 2012 at 02:20:56PM -0500, Tom Lane wrote:
>> I believe that we'd be better off doing something in postmaster.c to
>> positively ensure that each session has a distinct seed value.  Notice
>> that BackendRun() already takes measures to ensure that's the case for
>> the regular libc random() function; it seems like a reasonable extension
>> to also worry about OpenSSL's PRNG.

>> #ifdef USE_SSL
>> if (EnableSSL)
>> {
>>    struct timeval tv;
>> 
>>    gettimeofday(&tv, NULL);
>>    RAND_add(&tv, sizeof(tv), 0);
>> }
>> #endif

> Take the caution one step further and make it independent of EnableSSL.  In a
> stock installation, a !EnableSSL postmaster will never seed its PRNG, and
> there's no vulnerability.  Add a shared_preload_libraries module that uses the
> OpenSSL PRNG in its _PG_init(), and suddenly you're vulnerable again.

Meh.  In a postmaster that wasn't built with SSL support at all, such
a module is still dangerous (and I'm not convinced anybody would build
such a module anyway).  I think we should confine our ambitions to
preventing security issues caused by our own code.
        regards, tom lane