Bug 819896

Summary: host-based ssh authentication does not work because sshd-keygen does not set group readable bit on host keys to enable ssh-keysign to read them
Product: [Fedora] Fedora Reporter: Andrew J. Schorr <aschorr>
Component: opensshAssignee: Petr Lautrbach <plautrba>
Status: CLOSED CURRENTRELEASE QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: high Docs Contact:
Priority: unspecified    
Version: 19CC: mattias.ellert, mgrepl, plautrba, tmraz
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Target Release: ---   
Hardware: All   
OS: Unspecified   
Fixed In Version: Doc Type: Bug Fix
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Clone Of: Environment:
Last Closed: 2013-04-17 02:56:43 EDT Type: Bug
Regression: --- Mount Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description Flags
Enable group read on ssh host keys none

Description Andrew J. Schorr 2012-05-08 10:30:01 EDT
Created attachment 583009 [details]
Enable group read on ssh host keys

Description of problem: The /usr/libexec/openssh/ssh-keysign is setgid, not setuid as it used to be.  The group is set to ssh_keys.  In the /usr/sbin/sshd-keygen script, the keys are created with the group set to ssh_keys, but the group read bit is disabled.  Thus, only root can read the keys, and host-based authentication does not work.

Version-Release number of selected component (if applicable):

How reproducible:  Try to use host-based authentication.  You get an error like this:

could not open any host key
ssh_keysign: no reply
key_sign failed
Permission denied (publickey,hostbased)

Steps to Reproduce:
1. Install Fedora.
2. Look at permissions on /etc/ssh/ssh_host_*key
Actual results:
bash-4.2$ ls -l /etc/ssh/ssh_host_*key
-rw------- 1 root ssh_keys  668 May  7 15:22 /etc/ssh/ssh_host_dsa_key
-rw------- 1 root ssh_keys  965 May  7 15:22 /etc/ssh/ssh_host_key
-rw------- 1 root ssh_keys 1679 May  7 15:22 /etc/ssh/ssh_host_rsa_key

Expected results:
bash-4.2$ ls -l /etc/ssh/ssh_host_*key
-rw-r----- 1 root ssh_keys  668 May  7 15:22 /etc/ssh/ssh_host_dsa_key
-rw-r----- 1 root ssh_keys  965 May  7 15:22 /etc/ssh/ssh_host_key
-rw-r----- 1 root ssh_keys 1679 May  7 15:22 /etc/ssh/ssh_host_rsa_key

Additional info:
Comment 1 Petr Lautrbach 2012-05-09 08:00:25 EDT
Given that openssh package is built with openssh-5.8p1-keyperm.patch, which enables key files owned by ssh_keys group with 0640 permissions, I've reverted 81da99ed9bb19f029edfb92f6a8839886777db49 in git. 

Thanks for the report.
Comment 2 Fedora End Of Life 2013-04-03 16:30:03 EDT
This bug appears to have been reported against 'rawhide' during the Fedora 19 development cycle.
Changing version to '19'.

(As we did not run this process for some time, it could affect also pre-Fedora 19 development
cycle bugs. We are very sorry. It will help us with cleanup during Fedora 19 End Of Life. Thank you.)

More information and reason for this action is here: