I generated a new host key for one of our systems using:
ssh-keygen -t rsa -b 4096 -f ssh_host_rsa_key_4096
I then ran 'ls -Z on the keys'
ll -Z *key* -rw-------. root root system_u:object_r:sshd_key_t:s0 ssh_host_dsa_key -rw-r--r--. root root system_u:object_r:sshd_key_t:s0 ssh_host_dsa_key.pub -rw-------. root root system_u:object_r:sshd_key_t:s0 ssh_host_key -rw-r--r--. root root system_u:object_r:sshd_key_t:s0 ssh_host_key.pub -rw-------. root root system_u:object_r:sshd_key_t:s0 ssh_host_rsa_key -rw-------. root root unconfined_u:object_r:sshd_key_t:s0 ssh_host_rsa_key_4096 -rw-r--r--. root root unconfined_u:object_r:sshd_key_t:s0 ssh_host_rsa_key_4096.pub -rw-r--r--. root root system_u:object_r:sshd_key_t:s0 ssh_host_rsa_key.pub
As it seems odd, to me, that all the other files had a system_u user while the new had unconfined_u. So, I decided to run restorecon -v to presumably set the SELinux user correctly for the new keys: But that is not what happened:
restorecon -v *
restorecon reset /etc/ssh/ssh_host_rsa_key_4096 context unconfined_u:object_r:sshd_key_t:s0->unconfined_u:object_r:etc_t:s0
restorecon reset /etc/ssh/ssh_host_rsa_key_4096.pub context unconfined_u:object_r:sshd_key_t:s0->unconfined_u:object_r:etc_t:s0
As you can see, not only did the user not get set to system_u but the type was changed to etc_t.
Why were the new key files changed from sshd_key_t types to the generic etc_t types? Why was the user not changed in either case from unconfined_u to system_u or vice versa?
There is no REQUIREMENT that a host key have a particular file name is there? The sshd_config provides for setting one explicitly and doing so seems to cause no problems with ssh connections that I have yet encountered.
On 02/09/2015 11:14 AM, James B. Byrne wrote:
So, I decided to run restorecon -v to presumably set the SELinux user correctly for the new keys: But that is not what happened:
restorecon -v *
restorecon reset /etc/ssh/ssh_host_rsa_key_4096 context unconfined_u:object_r:sshd_key_t:s0->unconfined_u:object_r:etc_t:s0
restorecon reset /etc/ssh/ssh_host_rsa_key_4096.pub context unconfined_u:object_r:sshd_key_t:s0->unconfined_u:object_r:etc_t:s0
As you can see, not only did the user not get set to system_u but the type was changed to etc_t.
Why were the new key files changed from sshd_key_t types to the generic etc_t types? Why was the user not changed in either case from unconfined_u to system_u or vice versa?
There is no REQUIREMENT that a host key have a particular file name is there? The sshd_config provides for setting one explicitly and doing so seems to cause no problems with ssh connections that I have yet encountered.
The "system_u" vs. "unconfined_u" is inconsequential. That just comes from process that set the label.
Looking at the file labeling rules, only the 7 specific file names get a type of "sshd_key_t", and, strangely, not the /etc/ssh directory itself, so /restorecon/ will just make any other file there inherit the type of the directory, which is "etc_t". At first glance that looks like a bug, but perhaps there is come reason for that.
Ask about it on the selinux list at lists.fedoraproject.org.
On Feb 9, 2015, at 12:27 PM, Robert Nichols rnicholsNOSPAM@comcast.net wrote:
On 02/09/2015 11:14 AM, James B. Byrne wrote:
So, I decided to run restorecon -v to
...
restorecon reset /etc/ssh/ssh_host_rsa_key_4096 context unconfined_u:object_r:sshd_key_t:s0->unconfined_u:object_r:etc_t:s0
...
There is no REQUIREMENT that a host key have a particular file name is there? The sshd_config provides for setting one explicitly and doing so seems to cause no problems with ssh connections that I have yet encountered.
The "system_u" vs. "unconfined_u" is inconsequential. That just comes from process that set the label.
Looking at the file labeling rules, only the 7 specific file names get a type of "sshd_key_t", and, strangely, not the /etc/ssh directory itself, so /restorecon/ will just make any other file there inherit the type of the directory, which is "etc_t". At first glance that looks like a bug, but perhaps there is come reason for that.
If you want to use a non-default filename for something, so that the pre-defined regexes which restorecon uses won’t match on it, you can either add a new regex to the policy which will be persistent or just use chcon to set the type manually. — Mark Tinberg mark.tinberg@wisc.edu
On 10 February 2015 at 06:32, Mark Tinberg mark.tinberg@wisc.edu wrote:
On Feb 9, 2015, at 12:27 PM, Robert Nichols rnicholsNOSPAM@comcast.net
wrote:
On 02/09/2015 11:14 AM, James B. Byrne wrote:
So, I decided to run restorecon -v to
...
restorecon reset /etc/ssh/ssh_host_rsa_key_4096 context unconfined_u:object_r:sshd_key_t:s0->unconfined_u:object_r:etc_t:s0
Why are you putting your SSH key in /etc/ ?
With SELinux its normally better to go with the flow. find out which directories have the desired label and keep your objects in there.
I'm guessing in this case ~/.ssh/
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Andrew Holway -
James B. Byrne -
Mark Tinberg -
Robert Nichols