Bug #71915 [Asn]: openssl_random_pseudo_bytes is not "fork-safe"

Edit report at https://bugs.php.net/bug.php?id=71915&edit=1 ID: 71915 Updated by: bukka@php.net Reported by: mathieuk at gmail dot com Summary: openssl_random_pseudo_bytes is not "fork-safe" Status: Assigned Type: Bug Package: OpenSSL related Operating System: any PHP Version: 5.6.19 Assigned To: bukka Block user comment: N Private report: N New Comment: Ah I see what's the issue - finally read the links... :). Reading and thinking about it a bit more, the RAND_poll is probably reasonable. It would be good to know if there is any visible slow down though. Not that it would be a blocker but rather to see if we should have also consider some other solutions like addressing that in the SAPI's possibly (which might not be a great idea though). Anyway I will have to think about it a bit more so will leave this for a couple of days. Previous Comments: ------------------------------------------------------------------------ [2016-03-29 19:33:24] mathieuk at gmail dot com I've moved it to https://github.com/php/php-src/pull/1843 @bukka Seeding with PID and time already happens after each call to RAND_bytes() and is what caused this behaviour in the first place. Apache's mod_ssl calls RAND_seed() with a few bytes from /dev/urandom (or egd) for each request - we could do that instead, but it seems like that's pretty much what RAND_poll() does. What are you seeing as the heavy part of RAND_poll? @krakjoe Right. This would work fine in mod_php, but maybe not FPM. I could force the bool to false in PHP_RINIT_FUNCTION(openssl). Think that'd work better? ------------------------------------------------------------------------ [2016-03-29 19:09:22] bukka@php.net Yeah there seems to be missing global init which should reset the value for each request (PHP_GINIT_FUNCTION). Then it should be fine and the entropy would be added for the first call of the openssl_random_pseudo_bytes in the request. It means it can be added multiple time if the same process is used for more requests (fpm) which I'm not sure is ideal but might not be an issue. Again I might be wrong. ------------------------------------------------------------------------ [2016-03-29 18:54:12] krakjoe@php.net Well, COW duplicated ... the same data whatever ... ------------------------------------------------------------------------ [2016-03-29 18:53:04] krakjoe@php.net It's not sensible to use module globals, these are duplicated on fork. So if the parent process has already called a function that results in reseed, or poll, the child process will not make the call ... ------------------------------------------------------------------------ [2016-03-29 18:40:47] bukka@php.net I think that calling RAND_poll on the first call openssl_random_pseudo_bytes in each request is quite overkill and it might cause some perf regressions. RAND_poll is an expensive call. Wouldn't be enough to use RAND_seed / RAND_add (it's the same in the default rand method) with PID for example. P.S. I'm not a rand expert but hope that it shouldn't have any impact on randomness. But might be wrong. :) In any case RAND_poll seems just too much... ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=71915 -- Edit this bug report at https://bugs.php.net/bug.php?id=71915&edit=1