Re: in openpam_load_module(): no pam_unix.so found

On Mon, Sep 24, 2007 at 09:29:08AM -0400, Victor Star wrote:
==- 8< -========================================================================
fireball# ldd /usr/lib/pam_unix.so
/usr/lib/pam_unix.so:
libutil.so.5 => /lib/libutil.so.5 (0x28167000)
libcrypt.so.3 => /lib/libcrypt.so.3 (0x28173000)
libypclnt.so.2 => /usr/lib/libypclnt.so.2 (0x2818b000)
libpam.so.3 => /usr/lib/libpam.so.3 (0x2818f000)
fireball# ldd /usr/lib/pam_unix.so.3
/usr/lib/pam_unix.so.3:
libutil.so.5 => /lib/libutil.so.5 (0x28167000)
libcrypt.so.3 => /lib/libcrypt.so.3 (0x28173000)
libypclnt.so.2 => /usr/lib/libypclnt.so.2 (0x2818b000)
libpam.so.3 => /usr/lib/libpam.so.3 (0x2818f000)

Hmm. That all looks ok.

The relevant code inside openpam[1] does something like

dlopen(OPENPAM_MODULES_DIR . "/pam_unix.so.3", RTLD_NOW)

and if that fails, tries

dlopen(OPENPAM_MODULES_DIR . "/pam_unix.so", RTLD_NOW)

Both of these must have failed when su ran.

It may be worth compiling the following:

: mike@wafer:~ ; cat dlopentest.c
#include <dlfcn.h>
#include <stdio.h>

int
main (int argc, char **argv) {

void *dlh;

dlh = dlopen(argv[1], RTLD_NOW);
if (dlh) {
printf("dlopen %s worked\n", argv[1]);
} else {
printf("dlopen %s failed: %s\n", argv[1], dlerror());
}
return 0;
}
: mike@wafer:~ ; make dlopentest
cc -O2 -fno-strict-aliasing -pipe -march="pentium3" dlopentest.c -o dlopentest
: mike@wafer:~ ; ./dlopentest /usr/lib/pam_unix.so
dlopen /usr/lib/pam_unix.so worked
: mike@wafer:~ ; ./dlopentest /usr/lib/pam_unix.so.3
dlopen /usr/lib/pam_unix.so.3 worked
: mike@wafer:~ ; ./dlopentest /usr/lib/pam_kasjajsk.so
dlopen /usr/lib/pam_kasjajsk.so failed: Cannot open "/usr/lib/pam_kasjajsk.so"
: mike@wafer:~ ;

this may give you a clue as to why the dlopen failed. If that
doesn't point at a problem, then recompile su with _openpam_debug
= 1, and setup syslog to log LOG_DEBUG messages somewhere and see
what happens.


[1] assuming a version of FreeBSD suitably similar to the one I
have here, of course.




==- 8< -========================================================================

As for when it stopped working - the first thing I did is trying to recall if I updated any ports.
I've even went so far as looking for all files in /usr/ modified within the date range, but no,
nothing.

I did update php5 couple days before that. But it still worked for about two days after that.
And I don't have apache/php opened to outside anyway. Just mail ports and ssh on high port (closed
it for now for just in case anyway).

Victor

====- 8< -===================================================
su: in openpam_load_module(): no pam_unix.so found
su: pam_start: system error
====- 8< -===================================================

pam_unix.so is in /usr/lib:
====- 8< -===================================================
# ls -l /usr/lib/pam_unix*
lrwxr-xr-x 1 root wheel 13 Sep 25 2006 /usr/lib/pam_unix.so -> pam_unix.so.3
-r--r--r-- 1 root wheel 10240 Feb 19 2007 /usr/lib/pam_unix.so.3
# file /usr/lib/pam_unix.so
/usr/lib/pam_unix.so: symbolic link to `pam_unix.so.3'
====- 8< -===================================================

First, this is how a problem should be described, great work.

When openpam can't load a module, it also print's the 'not found' message.
With 'ldd /usr/lib/pam_unix.so.3' you can see if all the libraries that
it needs are in place. On my systems it give's the following output:

$ ldd /usr/lib/pam_unix.so.3
/usr/lib/pam_unix.so.3:
libutil.so.5 => /lib/libutil.so.5 (0x28169000)
libcrypt.so.3 => /lib/libcrypt.so.3 (0x28175000)
libypclnt.so.2 => /usr/lib/libypclnt.so.2 (0x2818d000)
libpam.so.3 => /usr/lib/libpam.so.3 (0x28191000)

====- 8< -===================================================
Sep 18 11:11:37 xxxxxx su: BAD SU <myloginname> to root on /dev/ttyp3
Sep 18 11:13:46 xxxxxx sshd[45047]: Bad protocol version identification '\377\364\377\375\006quit' from <some ip here>
Sep 18 11:15:08 xxxxxx sshd[45056]: Received disconnect from <some ip here>: 2: Bad packet length 710099706.
====- 8< -===================================================

The first line is probably the result of the broken pam_unix.so, the
other two lines look to me as ssh bruteforce attacks.

But, when did it stopped working. Did you tried to update the world or something like that?



--
Best regards,
Victor

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