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Date:      Sun, 31 Jan 2010 12:37:19 +0100
From:      =?utf-8?Q?Piotr_Buli=C5=84ski?= <bulinskp@iem.pw.edu.pl>
To:        freebsd-current@freebsd.org
Subject:   Problem with sftp server, static linking, pam and nss_ldap.
Message-ID:  <4D59045B-6B03-440C-BCCC-C9C171621475@iem.pw.edu.pl>
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--Apple-Mail-6-1015314247
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Hello,

recently we moved our users database to LDAP server, but after that sftp =
stops=20
working on our students server.=20

We use:
 - OpenLDAP 2.4.21
 - nss_ldap-1.265_3
 - pam_ldap-1.8.5
 - FreeBSD 9.0-CURRENT FreeBSD 9.0-CURRENT #0: Mon Jan 25 18:52:41 CET =
2010 amd64

When I use sftp, it drops the connection:

{volt}-{~}% sftp localhost
Connecting to localhost...
Connection closed
{volt}-{~}%=20

After short investigation, I've found that problem is in=20
/usr/libexec/sftp-server program (which is our default subsystem in =
sshd):

{volt}-{~}% /usr/libexec/sftp-server=20
No user found for uid 5567
{volt}-{~}%=20

what was quite weird, because sshd works perfectly with users from LDAP =
server=20
(so I assume that PAM is configured correctly).

After that, I've tried to make a simple test with program below:

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
#include <sys/types.h>
#include <pwd.h>
#include <stdarg.h>
#include <stdio.h>
#include <unistd.h>

int
main(int argc, char **argv)
{
 struct passwd *user_pw;

 user_pw =3D getpwuid(getuid());

 if ((user_pw =3D getpwuid(getuid())) =3D=3D NULL) {
   fprintf(stderr, "No user found for uid %lu\n",
       (u_long)getuid());
   return 1;
 } else {
   fprintf(stderr, "It works %s!\nYour uid is: %lu\n",
       user_pw->pw_name,
       (u_long)getuid());
 }

 return 0;
}
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

which is almost copy-pasted from =
/usr/src/crypto/openssh/sftp-server-main.c

I've build it twice. Once with dynamic linking:

{volt}-{~}% cc -o test test.c        =20
{volt}-{~}% ./test
It works bulinskp!
Your uid is: 5567
{volt}-{~}%=20

another one with static linking:

{volt}-{~}% cc -o test -static test.c
{volt}-{~}% ./test                  =20
No user found for uid 5567
{volt}-{~}%=20

As you can see, it works great with dynamic linking, but if it's build =
with=20
static linking it can't get user information from LDAP database.

During the upgrade to OpenSSH 5.3p1 =
/head/secure/libexec/sftp-server/Makefile file changed a little bit:

revision 181111, Fri Aug 1 02:48:36 2008 UTC --->  revision 197679, Thu =
Oct 1 17:12:52 2009 UTC
LDADD=3D  -lssh -lcrypt -lcrypto -lz	     --->  LDADD=3D  -lcrypt =
-lcrypto -lz -static -lssh


So I've tried to build sftp-server without -static switch, but it result =
in failure like below:

{volt}-{/usr/src/secure/libexec/sftp-server}% sudo make
Warning: Object directory not changed from original =
/usr/src/secure/libexec/sftp-server
cc -O2 -pipe -fomit-frame-pointer -march=3Dopteron =
-I/usr/src/secure/libexec/sftp-server/../../../crypto/openssh -include =
ssh_namespace.h -std=3Dgnu99 -Wno-pointer-sign -c =
/usr/src/secure/libexec/sftp-server/../../../crypto/openssh/sftp-server.c
cc -O2 -pipe -fomit-frame-pointer -march=3Dopteron =
-I/usr/src/secure/libexec/sftp-server/../../../crypto/openssh -include =
ssh_namespace.h -std=3Dgnu99 -Wno-pointer-sign -c =
/usr/src/secure/libexec/sftp-server/../../../crypto/openssh/sftp-common.c
cc -O2 -pipe -fomit-frame-pointer -march=3Dopteron =
-I/usr/src/secure/libexec/sftp-server/../../../crypto/openssh -include =
ssh_namespace.h -std=3Dgnu99 -Wno-pointer-sign -c =
/usr/src/secure/libexec/sftp-server/../../../crypto/openssh/sftp-server-ma=
in.c
cc -O2 -pipe -fomit-frame-pointer -march=3Dopteron =
-I/usr/src/secure/libexec/sftp-server/../../../crypto/openssh -include =
ssh_namespace.h -std=3Dgnu99 -Wno-pointer-sign  -o sftp-server =
sftp-server.o sftp-common.o sftp-server-main.o -lssh -lcrypt -lcrypto =
-lz
/usr/lib/libssh.so: undefined reference to `ssh_add_recv_bytes'
/usr/lib/libssh.so: undefined reference to `ssh_roaming_write'
/usr/lib/libssh.so: undefined reference to `ssh_roaming_read'
*** Error code 1

Stop in /usr/src/secure/libexec/sftp-server.
{volt}-{/usr/src/secure/libexec/sftp-server}%=20

Do you have any idea how to make it works?

regards
--=20
Piotr Buli=C5=84ski
Informatyka na Wydziale Elektrycznym
Politechnika Warszawska=

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