[Bug 799605] Re: pam-auth-update creates a 'common-account' that fails with cached logins

[Steve Langasek]

> * Implement a (dummy?) "account" method in pam_ccreds and add that into the
> relevant profile for cached credentials in pam_auth_update

That's what needs to happen here.  pam_unix has no way of knowing why
the user's shadow entry is missing; and arguably this is a bug in your
NSS setup anyway rather than anything to do with PAM, because NSS should
be cached as well for offline use.

** Package changed: pam (Ubuntu) => libpam-ccreds (Ubuntu)

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https://bugs.launchpad.net/bugs/799605

Title:
  pam-auth-update creates a 'common-account' that fails with cached
  logins

Status in “libpam-ccreds” package in Ubuntu:
  New

Bug description:
  Running Ubuntu 11.04 on a Dell Mini 1018 Netbook

  On a system running LDAP, Kerberos and Cached Credentials, pam-auth-
  update creates a 'common-account' file that will always fail if the
  machine uses cached credentials (presumably because it's offline).

  The relevant lines from the common-account file:

  # here are the per-package modules (the "Primary" block)
  account	[success=1 new_authtok_reqd=done default=ignore]	pam_unix.so
  # here's the fallback if no module succeeds
  account	requisite			pam_deny.so
  # prime the stack with a positive return value if there isn't one already;
  # this avoids us returning an error just because nothing sets a success code
  # since the modules above will each just jump around
  account	required			pam_permit.so
  # and here are more per-package modules (the "Additional" block)
  account	required			pam_krb5.so minimum_uid=1000
  account	[success=ok new_authtok_reqd=done ignore=ignore user_unknown=ignore authinfo_unavail=ignore default=bad]	pam_ldap.so minimum_uid=1000
  # end of pam-auth-update config

  This will always fail if the machine is off-line, because pam_unix.so
  will fail and cause the module to end with the next line which makes
  pam_deny.so a requisite.

  As a patch, I have commented out all of common-account except the line
  requiring pam_permit.so, but this is unsatisfactory.

  Two solutions could be proposed:
  * Write a common-account file that will pass if all the component modules fail due to the user or the service being absent. That is - only fail if it is explicitly required to fail, rather than failing if pam_unix.so fails because the user is in ldap or cached.
  * Implement a (dummy?) "account" method in pam_ccreds and add that into the relevant profile for cached credentials in pam_auth_update

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