ftpd and PAM

[Daniel J Walsh]

Paul Howarth wrote:
> Daniel J Walsh wrote:
>> Paul Howarth wrote:
>>> Paul Howarth wrote:
>>>> The PAM config files for vsftpd and prpftpd look like this:
>>>>
>>>> #%PAM-1.0
>>>> session    optional     pam_keyinit.so    force revoke
>>>> auth       required     pam_listfile.so item=user sense=deny 
>>>> file=/etc/vsftpd/ftpusers onerr=succeed
>>>> auth       required     pam_shells.so
>>>> auth       include      system-auth
>>>> account    include      system-auth
>>>> session    include      system-auth
>>>> session    required     pam_loginuid.so
>>>>
>>>> So it makes sense for ftpd_t to be able to set the login uid and 
>>>> create a session keyring:
>>>>
>>>> logging_set_loginuid(ftpd_t)
>>>> allow ftpd_t self:key { write search link };
>>>>
>>>>
>>>> Curiously, I've done this locally but still get this AVC when 
>>>> logging in on proftpd, with an open dovecot IMAP session on the 
>>>> same server:
>>>>
>>>> type=AVC msg=audit(1182853960.377:103383): avc:  denied  { link } 
>>>> for pid=24601 comm="proftpd" scontext=root:system_r:ftpd_t:s0 
>>>> tcontext=root:system_r:dovecot_t:s0 tclass=key
>>>
>>> FWIW, I'm also getting in /var/log/secure:
>>>
>>> Jun 26 12:09:42 goalkeeper proftpd: PAM audit_log_user_message() 
>>> failed: Operation not permitted
>>> Jun 26 12:09:42 goalkeeper proftpd[25559]: 
>>> goalkeeper.intra.city-fan.org 
>>> (::ffff:192.168.2.20[::ffff:192.168.2.20]) - PAM(setcred): System error
>>> Jun 26 12:09:42 goalkeeper proftpd: pam_unix(proftpd:session): 
>>> session closed for user paul
>>> Jun 26 12:09:42 goalkeeper proftpd[25559]: 
>>> goalkeeper.intra.city-fan.org 
>>> (::ffff:192.168.2.20[::ffff:192.168.2.20]) - PAM(close_session): 
>>> System error
>>> Jun 26 12:09:42 goalkeeper proftpd[25559]: 
>>> goalkeeper.intra.city-fan.org 
>>> (::ffff:192.168.2.20[::ffff:192.168.2.20]) - FTP session closed.
>>>
>>> I don't see any AVCs to go with these, and adding:
>>>
>>> logging_send_audit_msg(ftpd_t)
>>>
>>> doesn't seem to help.
>>>
>>> Paul.
>>>
>> This could be caused by proftp not running as root and not having the 
>> auth_write capability.  So a DAC error could be causing this problem.
>
> Proftpd runs as nobody out of the box; what would I need to change to 
> fix this? Which object's DAC permissions are the problem?
proftpd would need to start as root and then setuid to "nobody"  When it 
does setuid it would need to keep AUDIT_WRITE capability.
>
>> type=AVC msg=audit(1182853960.377:103383): avc:  denied  { link } for 
>> pid=24601 comm="proftpd" scontext=root:system_r:ftpd_t:s0 
>> tcontext=root:system_r:dovecot_t:s0 tclass=key
>>
>> I have no idea what this even means.  :^) One of these days I need to 
>> investigate the kernel keyring.
>
> It doesn't seem to cause any problem, but I would like to know what it 
> is if you ever figure it out.
>
> Cheers, Paul.
>