2003-08-17 01:03:32

by Felix von Leitner

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Subject: 2.6.0-test3: setuid32(8) returns EAGAIN (WTF?!)

I just changed from 2.5.75 to 2.6.0-test3 and suddenly my imap server
fails to start (it's dovecot). It wrote to syslog:

Aug 17 02:58:02 hellhound dovecot: Dovecot starting up
Aug 17 02:58:03 hellhound imap-login: setuid(8) failed: Resource temporarily unavailable
Aug 17 02:58:03 hellhound dovecot: Login process died too early - shutting down

So I strace -f it, and sure enough, here is what happens:

[init, fork, tzfile...]
8094 chroot("/var/run/dovecot//login") = 0
8094 chdir("/") = 0
8094 setuid32(0x8) = -1 EAGAIN (Resource temporarily unavailable)

Now this does not appear to be a valid return value for setuid32, and
my understanding of POSIX and Susv3 is that dovecot is absolutely right
in barfing at this.

Why is this happening? Please fix!

Felix

PS: Time for a brown paper bag bug-fix release, if you ask me.


2003-08-18 19:43:49

by Andries Brouwer

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Subject: Re: 2.6.0-test3: setuid32(8) returns EAGAIN (WTF?!)

On Sun, Aug 17, 2003 at 03:03:36AM +0200, Felix von Leitner wrote:
> I just changed from 2.5.75 to 2.6.0-test3 and suddenly my imap server
> fails to start (it's dovecot). It wrote to syslog:
>
> Aug 17 02:58:02 hellhound dovecot: Dovecot starting up
> Aug 17 02:58:03 hellhound imap-login: setuid(8) failed: Resource temporarily unavailable
> Aug 17 02:58:03 hellhound dovecot: Login process died too early - shutting down
>
> So I strace -f it, and sure enough, here is what happens:
>
> [init, fork, tzfile...]
> 8094 chroot("/var/run/dovecot//login") = 0
> 8094 chdir("/") = 0
> 8094 setuid32(0x8) = -1 EAGAIN (Resource temporarily unavailable)
>
> Why is this happening?

In sys.c:set_user() we see

if (atomic_read(&new_user->processes) >=
current->rlim[RLIMIT_NPROC].rlim_cur &&
new_user != &root_user) {
free_uid(new_user);
return -EAGAIN;
}

which was added in patch-2.6.0-test2.
No doubt this causes your problem.

You might check what values these variables have for you.

Andries