freebsd security - Feb 2010 - kern.randompid sysctl value

HI,

1. ?What's the real value (in terms of security) of the random PIDs feature?

According to this book

http://books.google.es/books?id=gqKwaHmXp4YC&pg=PA50&lpg=PA50&dq=random+pids+security&source=bl&ots=jimAeOQK2Q&sig=WrsBiMAxU-lUCM3pdCjtIYfmiIo&hl=es&ei=OwVoS4nwGMeOjAek5ZCvCQ&sa=X&oi=book_result&ct=result&resnum=9&ved=0CCsQ6AEwCA#v=onepage&q=random%20pids%20security&f=false

I understand that the random PIDs wil be a good security measure against 
some exploits (books says "race conditions"). OpenBSD folks (focused
on
security) have the random PIDs by defaul, so

?why Freebsd don't use it by default?

2. ?What will be a real secure value for sysctl parameter? I mean 
'kern.randompid' isn't a boolean, but a large number which
determines
the numeric range to generate de random PIDs. ?1000, 10000, 100000?

Thanks in advance for aclarations.

PD. I've real this old post 
http://marc.info/?l=freebsd-security&m=99495048923300&w=2. Interesting.

-- 
I must not fear. Fear is the mind-killer. Fear is the little-death that 
brings total obliteration. I will face my fear. I will permit it to pass 
over me and through me. And when it has gone past I will turn the inner 
eye to see its path. Where the fear has gone there will be nothing. Only 
I will remain.

Bene Gesserit Litany Against Fear.

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Hi, Jordi,

On 2010/02/02 03:09, Jordi Espasa Clofent wrote:
> HI,
> 
> 1. ?What's the real value (in terms of security) of the random PIDs
> feature?
> 
> According to this book
> 
>
http://books.google.es/books?id=gqKwaHmXp4YC&pg=PA50&lpg=PA50&dq=random+pids+security&source=bl&ots=jimAeOQK2Q&sig=WrsBiMAxU-lUCM3pdCjtIYfmiIo&hl=es&ei=OwVoS4nwGMeOjAek5ZCvCQ&sa=X&oi=book_result&ct=result&resnum=9&ved=0CCsQ6AEwCA#v=onepage&q=random%20pids%20security&f=false
> 
> 
> I understand that the random PIDs wil be a good security measure against
> some exploits (books says "race conditions"). OpenBSD folks
(focused on
> security) have the random PIDs by defaul, so
> 
> ?why Freebsd don't use it by default?
Hmm...  My personal impression is that random PID won't help much, and
management scripts may expect the PID won't be recycled too early, say,
on a busy server.  If PIDs are allocated sequentially, we can expect
long time before one given PID will be used; with randomized allocation,
we can never tell since it is expensive to have kernel tell whether the
PID is being used, say, 1000 processes before.
> 2. ?What will be a real secure value for sysctl parameter? I mean
> 'kern.randompid' isn't a boolean, but a large number which
determines
> the numeric range to generate de random PIDs. ?1000, 10000, 100000?
It's a modules number.  The kernel will adjust it for you if you specify
a too large number, e.g. 100k.
> Thanks in advance for aclarations.
> 
> PD. I've real this old post
> http://marc.info/?l=freebsd-security&m=99495048923300&w=2.
Interesting.
I think Peter's reply still apply...

Cheers,
- -- 
Xin LI <delphij@delphij.net>	http://www.delphij.net/
FreeBSD - The Power to Serve!	       Live free or die
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