Ok, so this is an old subject. I know that SSSD can only renew kerberos tickets which it
itself has generated which is part of the reason for KCM. But trying out RHEL8, with KCM
disabled (because of some weird behaviour reported in a bugzilla ticket), I am affected by
this much more than on RHEL7. On RHEL7, sssd manages to renew my kerberos ticket even if I
login to the server with sshd GSSAPI and forwarded credentials
('GSSAPIDelegateCredentials yes'). I am not sure why this works on RHEL7 when it
according to documentation should not.
On RHEL7, the krb5_child.log clearly shows that SSSD renews my ticket:
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [main] (0x0400): krb5_child
started.
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [unpack_buffer] (0x1000): total
buffer size: [163]
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [unpack_buffer] (0x0100): cmd [248]
uid [60483] gid [102] validate [true] enterprise principal [false] offline [false] UPN
[a001329(a)AD.EXAMPLE.COM]
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [unpack_buffer] (0x0100): ccname:
[KEYRING:persistent:60483] old_ccname: [KEYRING:persistent:60483] keytab:
[/etc/krb5.keytab]
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [check_use_fast] (0x0100): Not
using FAST.
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [switch_creds] (0x0200): Switch
user to [60483][102].
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [switch_creds] (0x0200): Switch
user to [0][0].
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [become_user] (0x0200): Trying to
become user [60483][102].
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [main] (0x2000): Running as
[60483][102].
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [k5c_setup] (0x2000): Running as
[60483][102].
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [set_lifetime_options] (0x0100):
Renewable lifetime is set to [7d]
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [set_lifetime_options] (0x0100): No
specific lifetime requested.
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [set_canonicalize_option] (0x0100):
Canonicalization is set to [true]
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [main] (0x0400): Will perform
ticket renewal
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [renew_tgt_child] (0x1000):
Renewing a ticket
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [validate_tgt] (0x2000): Found
keytab entry with the realm of the credential.
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [validate_tgt] (0x0400): TGT
verified using key for [LXSERV940$(a)AD.EXAMPLE.COM].
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [sss_send_pac] (0x0400): PAC
responder contacted. It might take a bit of time in case the cache is not up to date.
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [k5c_send_data] (0x0200): Received
error code 0
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [pack_response_packet] (0x2000):
response packet size: [115]
(Fri May 31 00:08:45 2019) [[sssd[krb5_child[62512]]]] [main] (0x0400): krb5_child
completed successfully
And as I said, this ticket is forwarded via SSH (logging in to the server via ssh with
sssd debugging on yields no log at all from krb5_child, so SSSD is not involved in getting
the ticket).
So, how does this work on RHEL7 and why does it not work on RHEL8?
Thanks.
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