I've been looking into this bug, and the problem comes from how adduser
(which calls useradd) places an account into /etc/shadow. Based on the
default options, here is what a test account from /etc/shadow looks like
test:$6$34MquWg3$Nar6/FMoE6Aj3AgcpNgbPQq.Ww2CowvAWeujm7qt9AdqskPtrLj3we4hYw8JsGSA6KN3t4dhlTL4uJmxi9RuJ/:0:0:99999:7:::
Breaking this down, this account has the following settings
Username: test
Encrypted Password (which is test):
$6$34MquWg3$Nar6/FMoE6Aj3AgcpNgbPQq.Ww2CowvAWeujm7qt9AdqskPtrLj3we4hYw8JsGSA6KN3t4dhlTL4uJmxi9RuJ/
Days since epoch that the password was last changed: 0
Days before password may be changed: 0
Days after which a password must be changed: 99999 (libshadow considers this
infinite)
Days before password is to expire that user is warned: 7
Days after password expires that account is disabled: NULL
Days since epcoh that account is disabled: NULL
According to the source code, for an account that should not be disabled
should have the last and max fields blank, and not zero:
Relevant sourcecode:
/*
* The last and max fields must be present for an account
* to have an expired password. A maximum of >10000 days
* is considered to be infinite.
*/
if (sp->sp_lstchg == -1 ||
sp->sp_max == -1 || sp->sp_max >= (10000L * DAY / SCALE))
return 0;
(just to ease any confusion, a blank field is returned -1).
Changing the test shadow line to:
test:$6$34MquWg3$Nar6/FMoE6Aj3AgcpNgbPQq.Ww2CowvAWeujm7qt9AdqskPtrLj3we4hYw8JsGSA6KN3t4dhlTL4uJmxi9RuJ/:::99999:7:::
allows successful login.
Running a few tests, and poking adduser's source reveals the problem is
with useradd. useradd has a command line switch for setting an
expiration date, but by default, generates a shadow line that looks like
this:
test2:!:0:0:99999:7:::
So in the end, its a bug in useradd, it simply should omit the field vs.
placing a zero in it.
--
if system date is set to 01-01-1970 users are enforced to update their password
https://bugs.launchpad.net/bugs/349504
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