pam_unix: Return PAM_AUTHINFO_UNAVAIL when appropriate.

The pam_unix.so will never return PAM_AUTHINFO_UNAVAIL on systems
that use the unix_chkpwd helper.

The reason is that in unix_chkpwd.c, towards the end of main(), if
helper_verify_password() does not return PAM_SUCCESS, main() ignores
the actual error that helper_verify_password() returned and instead
returns PAM_AUTH_ERR.

This commit corrects this behavior.  Specifically, if
helper_verify_password() returns PAM_USER_UNKNOWN, which it does
when /etc/passwd entry indicates that shadow information is present
but the /etc/shadow entry is missing, the unix_chkpwd now exits
with PAM_AUTHINFO_UNAVAIL. For any other error from
helper_verify_password(), unix_chkpwd continues to exit with
PAM_AUTH_ERR.

* modules/pam_unix/unix_chkpwd.c (main): Return PAM_AUTHINFO_UNAVAIL
when helper_verify_password() returns PAM_USER_UNKNOWN.

0 files changed, 0 insertions, 0 deletions