permission denied on authorized_key file

On fedora 16
I copied my public key to /home/user/.ssh/authorized_keys file user comes from ldap.

But could not authenticate over ssh without password for this user.

It works for root.

strace on sshd

[pid 24834] setgroups(1, [1100])        = 0
[pid 24834] getgroups(0, NULL)          = 1
[pid 24834] getgroups(1, [1100])        = 1
[pid 24834] setgroups(1, [1100])        = 0
[pid 24834] setresgid(-1, 1100, -1)     = 0
[pid 24834] setresuid(-1, 1040, -1)     = 0
[pid 24834] open("/home/user/.ssh/authorized_keys", O_RDONLY|O_NONBLOCK) = -1 EACCES (Permission denied)

• I tried to access to the file with user account: no problem.
• I tried with a tiny C program with same options above: no problem.
• I tried with 777 right: no problem.

ls -l on authorized_keys file:

-rw-r--r--. 1 user user  784 19 nov.  16:24 authorized_keys

• I tried to disable StrictMode (and restarting sshd)

I compared with an other fedora 16:

• same OS
• same sshd_config file
• same permissions on ~/, ~/.ssh/ and ~/.ssh/authorized_keys

And now, I don't know what to try to troubleshoot it.

It might be SE Linux. If the context of the file isn't correct, running this as root should fix.

restorecon -Rv /home/user/.ssh

Also check the permissions on /home/user/.ssh aren't wide open. SSHD is quite particular about this.

chmod 0700 /home/user/.ssh

I had a similar issue, and in my case the cause was wrong ownership of both the .ssh directory and .ssh/authorized_keys file. To fix that, in /home/user as root:

chown user:user .ssh
chown user:user .ssh/authorized_keys

Your authorized_keys file should have permissions rw-------. Run:

chmod 600 ~/.ssh/authorized_keys

And just as a note your private key (typically id_rsa) on the client should have the same permissions.