On Thu, 2014-05-22 at 10:11 +0200, Sumit Bose wrote:
Hi,
I would like to use getpwnam() to find the POSIX user for a given
Kerberos principal. To achieve this I have to change the
regular-expression we use to split the user name into name and domain
components because we use '@' as a delimiter here and Kerberos
principals contain an '@' as well.
My idea is to allow an '@' in the name part so that 'a@b@c' is split
into the name part 'a@b' and the domain part 'c'. A name containing an
'@' will then be considered as a Kerberos principal by SSSD and used
accordingly. If the domain is not known and the Kerberos principal
should be searched in all known domains a single '@' at the end, e.g.
'a@b@' shall indicate that the argument is a Kerberos principal.
I would like to know if you agree with this approach, if you have
concerns and other suggestions?
As a side node. While looking at this I found some oddities in the
current regular-expressions. E.g. currently '@' is not allowed in the
name part, but in the domain part when '@' is the separator. This leads
to a splitting of 'a@b@c' to name 'a' and domain 'b@c'. For
AD-style
names with '\' as a separator '@' is allowed in names, i.e.
'a\b@c' will
be result in name 'b@c' and domain 'a' (so in theory I could use this
scheme to send a Kerberos principal to SSSD, but for me this looks even
stranger than my suggestion above, it hard to use on the command-line
and does not solve the case where the domain is not known). I will try
to fix those inconsistencies as well.
I don't like this much.
Instinctively I would say the current scheme should be just fine, if you
pass in name@REALM you get REALM as the domain name. If they match (bar
case), then you search for name as the username. If they do not match
and you end up finding no domain, then we can internally decide to
search all domain using name@REALM as the principal in a ldb_search().
Where does this break ?
Is it possible to have a user foo in domain
example.com that has a
principal of bar(a)EXAMPLE.COM ? And at the same time also have a user
'bar' in the same domain ?
Is this the case you are trying to handle ? How likely is it ?
Btw, I was thinking whether we should handle cases where you pass in
things like root/admin@REALM this would require some special mapping
rules ... have you thought about these cases ?
Simo.
--
Simo Sorce * Red Hat, Inc * New York