On 10/05/2010 06:38 AM, imsand@xxxxxxxxx wrote:
On 10/04/2010 11:30 PM, imsand@xxxxxxxxx wrote:
On 10/04/2010 01:03 AM, imsand@xxxxxxxxx wrote:
Hello
I'm working on SUSE SLES11SP1 and encounter the following problem.
Setting the context of the User after ssh login doesn't work if the
SELinux Username and the Linux Username aren't identical.
--------------
Here is an example (SElinux User=mat_u, Linux User=mat_u):
Oct 4 09:41:54 testsrv.example sshd[15829]: Accepted
keyboard-interactive/pam for mat_u from 131.102.233.125 port 54714
ssh2
Oct 4 09:41:54 testsrv.example sshd[15829]:
pam_selinux(sshd:session):
Open Session
Oct 4 09:41:54 testsrv.example sshd[15829]:
pam_selinux(sshd:session):
Open Session
Oct 4 09:41:54 testsrv.example sshd[15829]:
pam_selinux(sshd:session):
Username= mat_u SELinux User = user_u Level= (null)
Oct 4 09:41:54 testsrv.example sshd[15829]:
pam_selinux(sshd:session):
set mat_u security context to user_u:user_r:user_t
Oct 4 09:41:54 testsrv.example sshd[15829]:
pam_selinux(sshd:session):
set mat_u key creation context to user_u:user_r:user_t
---
mat_u@xxxxxxxxxxxxxxx:~> id
uid=6575(mat_u) gid=100(users) groups=16(dialout),33(video),100(users)
context=mat_u:staff_r:staff_t
mat_u@xxxxxxxxxxxxxxx:~> newrole -r sysadm_r
mat_u@xxxxxxxxxxxxxxx:~> id
uid=6575(mat_u) gid=100(users) groups=16(dialout),33(video),100(users)
context=mat_u:sysadm_r:sysadm_t
--------------------
So, this is okey. The user's context after login is
"mat_u:staff_r:staff_t"
But, if the Linux User is different from the SELinux User, the default
user's will be chosen instead.
Here is the example (SELinux User=mat_u, Linux User=mat):
---------------------
Oct 4 09:46:22 testsrv.example sshd[16185]: Accepted
keyboard-interactive/pam for mat from 131.102.233.125 port 54726 ssh2
Oct 4 09:46:22 testsrv.example sshd[16185]:
pam_selinux(sshd:session):
Open Session
Oct 4 09:46:22 testsrv.example sshd[16185]:
pam_selinux(sshd:session):
Open Session
Oct 4 09:46:22 testsrv.example sshd[16185]:
pam_selinux(sshd:session):
Username= mat SELinux User = mat_u Level= (null)
Oct 4 09:46:22 testsrv.example sshd[16185]:
pam_selinux(sshd:session):
set mat security context to mat_u:staff_r:staff_t
Oct 4 09:46:22 testsrv.example sshd[16185]:
pam_selinux(sshd:session):
set mat key creation context to mat_u:staff_r:staff_t
---
mat_u@xxxxxxxxxxxxxxx:~> id
uid=6575(mat) gid=100(users) groups=16(dialout),33(video),100(users)
context=user_u:user_r:user_t
mat_u@xxxxxxxxxxxxxxx:~> newrole -r sysadm_r
user_u:sysadm_r:sysadm_t is not a valid context
---------------------
As you can see, the pam_selinux module recognizes that the new context
should be "mat_u:staff_r:staff_t", but for some reason the real
context
is
user_u:user_r:user_t. Changing the context with newrole doesn't work
either...
The user mappings should be okey:
------
semanage user -l | grep mat
mat_u staff_r sysadm_r
testsrv.example:~ # semanage login -l | grep mat
mat
-------
Any idea out there? Do I miss something?
kind regards
Matthias
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you can specify the context in
/etc/selinux/policy/contexts/users/whatroleyouused
(under sshd) I normally set user_r:user_t:s0
Justin P. Mattock
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The file looks like:
cat /etc/selinux/refpolicy/contexts/users/mat_u
system_r:local_login_t staff_r:staff_t sysadm_r:sysadm_t
system_r:remote_login_t staff_r:staff_t
system_r:sshd_t staff_r:staff_t sysadm_r:sysadm_t
system_r:crond_t staff_r:cronjob_t
system_r:xdm_t staff_r:staff_t
staff_r:staff_su_t staff_r:staff_t
staff_r:staff_sudo_t staff_r:staff_t
sysadm_r:sysadm_su_t sysadm_r:sysadm_t
sysadm_r:sysadm_sudo_t sysadm_r:sysadm_t
So, theoretical this should be okey, isn't it?
And as you can see in the log from above (set mat key creation context
to
mat_u:staff_r:staff_t) it "tries" to switch to staff but for some reason
it doesn't work..
if your sshd'ing and the context is staff_r:staff_t then it's correct, I
usually change this to user_r:user_t just cause I'm paranoid.
Also there is some options that you can set in /etc/pam.d to do other
checks etc..
Justin P. Mattock
no it's not and that't the problem:)
If I sshd'ing with mat_u it's always "user_r:user_t" even
"staff_r:staff_t" is specified (see above). But it's correct if the
selinux and linux users are named equaly (mat in the example).
It seems that something with the context settings and usermapping isn't
correct. Do you see the problem?
Somewhere in the policy it is set to default to user_r for sshd, I dont
think there is a boolean(but could be wrong)for that feature. maybe it's
reading the default_contexts file which is set to use user_r:user_t
instead of reading mat_u for sshd(staff_r:staff_t)
Justin P. Mattock
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