kern.randompid sysctl value
Jordi Espasa Clofent
1. �What's the real value (in terms of security) of the random PIDs feature?
According to this book
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.
Xin LI
Hash: SHA1
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 <del...@delphij.net> http://www.delphij.net/
FreeBSD - The Power to Serve! Live free or die
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.14 (FreeBSD)
iQEcBAEBAgAGBQJLaHAZAAoJEATO+BI/yjfB9c4H/An0Zpxh6ZNaKO1RvYfC9dBb
zTKKND9TBvFIzgIrfI7bTjdoSoFeJumpDRJ9MBrHcc5bwEfFD7yC8FFmdJKVEAna
u6uvu3ZR1wsaPRy4AVFPTGWrclFA7mTdB2nehJwMbXLAWclpoydG6gm1oxFKAOYi
epw3bwnjMLzkKuax84LVKtawF/0jr4fn/w3YpqZudCOYdD1LCtiFm/o0h6yhP8SN
dYAEUQ8h6WpcJOsqgbTB1SK+3eoK/7upwheEt0TLkbp2XX+0I35O0mJrBvn+Fbzy
VEEpSj6qoqLv6Pa3zfjM4YTc4ldgmqheCzDH57dZ7juDrveF2lOwSXG5tXtjc4o=
=IMZA
-----END PGP SIGNATURE-----