ipa-pwd-extop: use timegm() instead of mktime() to preserve timezone offset
"Kerberos principal expiration" is set in UTC and when server is in
different timezone, the time difference between timezone is respected by
the IPA server/client for Kerberos authentication.
The problem is due to mktime() assuming default time zone but since we
parse the time using Zulu (UTC+0) timezone, mktime() forces current time
zone offset added.
The method is using mktime() and comparing to the current time obtained
with time(NULL). According to its man page, mktime is considering the
time as local time:
The mktime() function converts a broken-down time structure, expressed
as local time, to calendar time representation.
Instead mktime() we should use timegm(). The problem is that it is
non-standard GNU extension and it is recommended (in the man page for
timegm(3)) to avoid its use. An alternative is to set TZ=UTC, call
mktime(), unset TZ, but since we are running in a multi-threaded
environment this is problematic.
On the other hand, we already rely on GNU extensions and enable them
with -D_DEFAULT_SOURCE=1, so use of timegm() is enabled already.
The fix, therefore, is to use timegm() instead of mktime() in
daemons/ipa-slapi-plugins/ipa-pwd-extop/prepost.c in two places where we
first do 'strptime()' with Zulu time zone (in ipapwd_pre_bind() and
ipapwd_write_krb_keys()).
Fixes: https://pagure.io/freeipa/issue/8362
Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Reviewed-By: Christian Heimes <cheimes@redhat.com>