svn commit: r249035 - head/lib/libc/stdlib

[Xin Li]

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On 4/3/13 12:31 AM, Andrey Chernov wrote:
> On 03.04.2013 11:04, Bruce Evans wrote:
>>> +    mib[0] = CTL_KERN; +    mib[1] = KERN_ARND; +
>>> sysctl(mib, 2, (void *)&next, &len, NULL, 0); }
>> 
>> The sysctl() is certain to fail on old kernels (like open of
>> /dev/random on even older kernels), but there is no longer any
>> error checking or handling.  The contents of `next' on error is
>> indeterminate (not documented in the man page), but is probably
>> unchanged.  Applications can actually detect this error although
>> though the API doesn't support this, by using the documented
>> implementation details and assuming that errno is properly left
>> changed if the syscall fails (set errno to 0 before the call here
>> and check it after).
> 
> Even in case sysctl is not fail, kernel's arc4 is very poorly 
> initialized right after the boot. See the comment in the 
> libkern/arc4random.c arc4_randomstir(), it is about device not
> loaded case, but it is the same even if device is loaded but not
> harvest enough. NetBSD implementation of kernel's arc4 is different
> from ours.

True, but keep mind that neither random(3) nor rand(3) is intended to
satisfy cryptographically secure needs, and I don't see a reason why
kernel arc4 can not be improved.

By the way, /dev/random won't even block about 5 weeks and was broken
in 2006.

> Really I am _very_ tired to tell people about the problem, to
> write patches for the problem, etc., so anybody who are interested
> can search more details and patches in the mail archives.

To be honest, I don't personally have access to the archive (nor I'm
aware there was one, the arc4 change you are talking about may predate
my membership on secteam@ by the way).

How about sending the patch again and let's see how we can work it out?

Cheers,
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