Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.unix.programmer > #876
| From | Eric Sosman <esosman@ieee-dot-org.invalid> |
|---|---|
| Newsgroups | comp.unix.programmer |
| Subject | Re: Why user can change password? |
| Date | 2011-06-29 22:29 -0400 |
| Organization | A noiseless patient Spider |
| Message-ID | <iugn32$eph$1@dont-email.me> (permalink) |
| References | <8d6a4a86-6fdf-4183-bfba-5ed322a98195@u28g2000yqf.googlegroups.com> <iufdjn$f79$1@reader1.panix.com> <iugk9c$2e1$1@speranza.aioe.org> |
On 6/29/2011 9:42 PM, Golden California Girls wrote:
> On 6/29/11 7:41 AM, John Gordon wrote:
>> It runs as root, and has permission
>> to do anything root could do (which is everything.)
>>
>
> I was under the impression that a program running as root was limited and
> can't do everything. An example being ignoring a kill, or reading and
> writing any address in any process space. These are things a driver can do
> as a driver is allowed to run CPU privileged instructions. Am I wrong and
> a program running as root can run CPU privileged instructions?
It can't ignore SIGKILL, no[*]. It also can't cure cancer,
repeal the laws of thermodynamics, or sprinkle maple syrup on the
DIMM's. So John was wrong: A root process cannot in fact do
"everything."
As for privileged instructions, I see no reason why a root
process couldn't run them. It'd probably need to jump through
some hoops first, but hoops don't deter root.
[*] Well, it could open /dev/kmem or equivalent, find the
spot where SIGKILL is delivered, and overwrite the instructions
to prevent the delivery. That might be an effective substitute.
--
Eric Sosman
esosman@ieee-dot-org.invalid
Back to comp.unix.programmer | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Why user can change password? Mateusz_madi <madi.czadi@gmail.com> - 2011-06-29 02:44 -0700
Re: Why user can change password? jt@toerring.de (Jens Thoms Toerring) - 2011-06-29 09:55 +0000
Re: Why user can change password? Ben Finney <ben+unix@benfinney.id.au> - 2011-06-29 22:36 +1000
Re: Why user can change password? jt@toerring.de (Jens Thoms Toerring) - 2011-06-29 15:03 +0000
Re: Why user can change password? John Gordon <gordon@panix.com> - 2011-06-29 14:41 +0000
Re: Why user can change password? Golden California Girls <gldncagrls@aol.com.mil> - 2011-06-29 18:42 -0700
Re: Why user can change password? Barry Margolin <barmar@alum.mit.edu> - 2011-06-29 22:29 -0400
Re: Why user can change password? Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-06-29 22:29 -0400
Re: Why user can change password? gordonb.h6afl@burditt.org (Gordon Burditt) - 2011-06-29 22:10 -0500
Re: Why user can change password? Nobody <nobody@nowhere.com> - 2011-06-30 18:10 +0100
csiph-web