[Bug 1760713] [NEW] getlogin_r is performing NSS lookups when loginid isn't set

[Charles F. Stephens]

Public bug reported:

For configurations that use networked naming services for passwd (in
particular LDAP), processes that have no login UID, there are excessive
delays when getlogin_r() is called.

For such processes, /proc/self/loginid is set to a sentinel value (-1),
when files is the only backend, or if nscd is running this returns
quickly.  However if ldap is configured as a backend for passwd, and
nscd isn't being used (which for various political and economic reasons
is not always feasible) network requests to the configured LDAP servers
will occur which can slow down process creation enough to cause timeouts
in parent processes in certain contexts.

Good news, however, as this was recently fixed upstream by:

https://sourceware.org/git/?p=glibc.git;a=commit;h=cc8a1620eb97ccddd337d157263c13c57b39ab71

** Affects: glibc (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1760713

Title:
  getlogin_r is performing NSS lookups when loginid isn't set

Status in glibc package in Ubuntu:
  New

Bug description:
  For configurations that use networked naming services for passwd (in
  particular LDAP), processes that have no login UID, there are
  excessive delays when getlogin_r() is called.

  For such processes, /proc/self/loginid is set to a sentinel value
  (-1), when files is the only backend, or if nscd is running this
  returns quickly.  However if ldap is configured as a backend for
  passwd, and nscd isn't being used (which for various political and
  economic reasons is not always feasible) network requests to the
  configured LDAP servers will occur which can slow down process
  creation enough to cause timeouts in parent processes in certain
  contexts.

  Good news, however, as this was recently fixed upstream by:

  https://sourceware.org/git/?p=glibc.git;a=commit;h=cc8a1620eb97ccddd337d157263c13c57b39ab71

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