LDAP - SFTP Chroot - Not totally functioning

G

GeorgeLinn

I am having a problem using LDAP with SFTP chrooted access on a FreeBSD 9.1-RC1 installation. LDAP works fine with SSH logins, LDAP also seems to authenticate chrooted SFTP sessions ok too, but once the SFTP session is active I can not get a simple directoy listing to work. The ls command seems to freeze for 10-20 minutes then eventualy works. After the initail dealy, ls command continues to work.

If I disable LDAP on the computer, the chrooted SFTP process works OK. Also, if I put a copy of the hosts file in to the chrooted SFTP environment there is no delay in the chrooted SFTP session while LDAP is enabled.

I think there is an issue with LDAP lookups only from within the SFTP chrooted session. Any thoughts as to why this is not working?
/etc/ssh/sshd_config excerpt

Code: 
Match Group sftpusers
    ChrootDirectory /mnt/home/%u
    AllowTCPForwarding no
    X11Forwarding no
    ForceCommand internal-sftp
Match

LDAP related ports installed:
Code: 
nss_ldap-1.265_7    RFC 2307 NSS module
openldap-client-2.3.43 Open source LDAP client implementation
 
Post your /etc/nsswitch.conf, your /usr/local/etc/openldap/ldap.conf, your /etc/hosts as well as the contents of your nss-ldap configuration. Lastly, tell us your jail's IP.
 
Thanks for taking the time to look at this. No jails are setup, the IP address of the machine is 192.168.101.32 and the machine name is ny-sftpc1.

/etc/nsswitch.conf
Code: 
#group: compat
group: files ldap
group_compat: nis
hosts: files dns
networks: files
passwd: files ldap
#passwd: compat
passwd_compat: nis
shells: files
services: compat
services_compat: nis
protocols: files
rpc: files


/usr/local/etc/openldap/ldap.conf

Code: 
#BASE   dc=example, dc=com
#URI    ldap://ldap.example.com ldap://ldap-master.example.com:666
BASE    dc=bsd4all, dc=com
#URI    ldap://ldap.example.com ldap://ldap-master.example.com:666
URI     ldap://ny-ldapcs1.bsd4all.com:389
#URI    ldap://192.168.101.51:389
#SIZELIMIT      12
#TIMELIMIT      15
#DEREF          never


/etc/hosts

Code: 
::1                     localhost localhost.my.domain
127.0.0.1               localhost localhost.my.domain

192.168.100.50          ny-ldapm ny-ldapm.bsd4all.com
192.168.101.51          ny-ldapcs1 ny-ldapcs1.bsd4all.com
192.168.100.51          ny-ldaps1 ny-ldaps1.bsd4all.com
192.168.100.52          ny-ldaps2 ny-ldaps2.bsd4all.com
192.168.101.32          ny-sftpc1 ny-sftpc1.bsd4all.com
 
/usr/local/etc/nss_ldap.conf

Code: 
# @(#)$Id: ldap.conf,v 1.36 2005/03/23 08:29:59 lukeh Exp $
#
# This is the configuration file for the LDAP nameservice
# switch library and the LDAP PAM module.
#
# PADL Software
# [url]http://www.padl.com[/url]
#

# Your LDAP server. Must be resolvable without using LDAP.
# Multiple hosts may be specified, each separated by a
# space. How long nss_ldap takes to failover depends on
# whether your LDAP client library supports configurable
# network or connect timeouts (see bind_timelimit).
#
[color="Red"][B]host ny-ldapcs1.bsd4all.com ny-ldaps2.bsd4all.com[/B][/color]
#host ny-ldapcs1.bsd4all.com 192.168.101.51


# The distinguished name of the search base.
[color="Red"][B]base ou=people,dc=bsd4all,dc=com[/B][/color]
# Another way to specify your LDAP server is to provide an
# uri with the server name. This allows to use
# Unix Domain Sockets to connect to a local LDAP Server.
#uri ldap://192.168.101.51/
#uri ldaps://192.168.101.51/
#uri ldapi://%2fvar%2frun%2fldapi_sock/
# Note: %2f encodes the '/' used as directory separator

# The LDAP version to use (defaults to 3
# if supported by client library)
#ldap_version 3

# The distinguished name to bind to the server with.
# Optional: default is to bind anonymously.
#binddn cn=replication,ou=people,dc=bsd4all,dc=com

# The credentials to bind with.
# Optional: default is no credential.
#bindpw password

# The distinguished name to bind to the server with
# if the effective user ID is root. Password is
# stored in /etc/ldap.secret (mode 600)
#rootbinddn cn=replication,ou=people,dc=bsd4all,dc=com

# The port.
# Optional: default is 389.
port 389

# The search scope.
#scope sub
#scope one
#scope base

# Search timelimit
#timelimit 30

# Bind/connect timelimit
#bind_timelimit 30

# Reconnect policy: hard (default) will retry connecting to
# the software with exponential backoff, soft will fail
# immediately.
#bind_policy hard

# Idle timelimit; client will close connections
# (nss_ldap only) if the server has not been contacted
# for the number of seconds specified below.
#idle_timelimit 3600

# Filter to AND with uid=%s
#pam_filter objectclass=account

# The user ID attribute (defaults to uid)
#pam_login_attribute uid

# Search the root DSE for the password policy (works
# with Netscape Directory Server)
#pam_lookup_policy yes

# Check the 'host' attribute for access control
# Default is no; if set to yes, and user has no
# value for the host attribute, and pam_ldap is
# configured for account management (authorization)
# then the user will not be allowed to login.
#pam_check_host_attr yes

# Check the 'authorizedService' attribute for access
# control
# Default is no; if set to yes, and the user has no
# value for the authorizedService attribute, and
# pam_ldap is configured for account management
# (authorization) then the user will not be allowed
# to login.
#pam_check_service_attr yes

# Group to enforce membership of
#pam_groupdn cn=PAM,ou=Groups,dc=padl,dc=com

# Group member attribute
#pam_member_attribute uniquemember

# Specify a minium or maximum UID number allowed
#pam_min_uid 0
#pam_max_uid 0

# Template login attribute, default template user
# (can be overriden by value of former attribute
# in user's entry)
#pam_login_attribute userPrincipalName
#pam_template_login_attribute uid
#pam_template_login nobody

# HEADS UP: the pam_crypt, pam_nds_passwd,
# and pam_ad_passwd options are no
# longer supported.
#
# If you are using XAD, you can set pam_password
# to racf, ad, or exop. Make sure that you have
# SSL enabled.

# Do not hash the password at all; presume
# the directory server will do it, if
# necessary. This is the default.
pam_password clear SSHA

# Hash password locally; required for University of
# Michigan LDAP server, and works with Netscape
# Directory Server if you're using the UNIX-Crypt
# hash mechanism and not using the NT Synchronization
# service.
#pam_password crypt

# Remove old password first, then update in
# cleartext. Necessary for use with Novell
# Directory Services (NDS)
#pam_password clear_remove_old
#pam_password nds

# RACF is an alias for the above. For use with
# IBM RACF
#pam_password racf

# Update Active Directory password, by
# creating Unicode password and updating
# unicodePwd attribute.
#pam_password ad

# Use the OpenLDAP password change
#extended operation to update the password.
#pam_password exop

# Redirect users to a URL or somesuch on password
# changes.
#pam_password_prohibit_message Please visit [url]http://internal[/url] to change your password.

# RFC2307bis naming contexts
# Syntax:
# nss_base_XXX          base?scope?filter
# where scope is {base,one,sub}
# and filter is a filter to be &'d with the
# default filter.
# You can omit the suffix eg:
# nss_base_passwd       ou=People,
# to append the default base DN but this
# may incur a small performance impact.
nss_base_passwd         ou=People,dc=bsd4all,dc=com?one
#nss_base_shadow        ou=People,dc=padl,dc=com?one
nss_base_group          ou=Groups,dc=bsd4all,dc=com?one
#nss_base_hosts         ou=Hosts,dc=padl,dc=com?one
#nss_base_services      ou=Services,dc=padl,dc=com?one
#nss_base_networks      ou=Networks,dc=padl,dc=com?one
#nss_base_protocols     ou=Protocols,dc=padl,dc=com?one
#nss_base_rpc           ou=Rpc,dc=padl,dc=com?one
#nss_base_ethers        ou=Ethers,dc=padl,dc=com?one
#nss_base_netmasks      ou=Networks,dc=padl,dc=com?ne
#nss_base_bootparams    ou=Ethers,dc=padl,dc=com?one
#nss_base_aliases       ou=Aliases,dc=padl,dc=com?one
#nss_base_netgroup      ou=Netgroup,dc=padl,dc=com?one

# attribute/objectclass mapping
# Syntax:
#nss_map_attribute      rfc2307attribute        mapped_attribute
#nss_map_objectclass    rfc2307objectclass      mapped_objectclass

# configure --enable-nds is no longer supported.
# NDS mappings
#nss_map_attribute uniqueMember member

# Services for UNIX 3.5 mappings
#nss_map_objectclass posixAccount User
#nss_map_objectclass shadowAccount User
#nss_map_attribute uid msSFU30Name
#nss_map_attribute uniqueMember msSFU30PosixMember
#nss_map_attribute userPassword msSFU30Password
#nss_map_attribute homeDirectory msSFU30HomeDirectory
#nss_map_attribute homeDirectory msSFUHomeDirectory
#nss_map_objectclass posixGroup Group
#pam_login_attribute msSFU30Name
#pam_filter objectclass=User
#pam_password ad

# configure --enable-mssfu-schema is no longer supported.
# Services for UNIX 2.0 mappings
#nss_map_objectclass posixAccount User
#nss_map_objectclass shadowAccount user
#nss_map_attribute uid msSFUName
#nss_map_attribute uniqueMember posixMember
#nss_map_attribute userPassword msSFUPassword
#nss_map_attribute homeDirectory msSFUHomeDirectory
#nss_map_attribute shadowLastChange pwdLastSet
#nss_map_objectclass posixGroup Group
#nss_map_attribute cn msSFUName
#pam_login_attribute msSFUName
#pam_filter objectclass=User
#pam_password ad

# RFC 2307 (AD) mappings
#nss_map_objectclass posixAccount user
#nss_map_objectclass shadowAccount user
#nss_map_attribute uid sAMAccountName
#nss_map_attribute homeDirectory unixHomeDirectory
#nss_map_attribute shadowLastChange pwdLastSet
#nss_map_objectclass posixGroup group
#nss_map_attribute uniqueMember member
#pam_login_attribute sAMAccountName
#pam_filter objectclass=User
#pam_password ad

# configure --enable-authpassword is no longer supported
# AuthPassword mappings
#nss_map_attribute userPassword authPassword

# AIX SecureWay mappings
#nss_map_objectclass posixAccount aixAccount
#nss_base_passwd ou=aixaccount,?one
#nss_map_attribute uid userName
#nss_map_attribute gidNumber gid
#nss_map_attribute uidNumber uid
#nss_map_attribute userPassword passwordChar
#nss_map_objectclass posixGroup aixAccessGroup
#nss_base_group ou=aixgroup,?one
#nss_map_attribute cn groupName
#nss_map_attribute uniqueMember member
#pam_login_attribute userName
#pam_filter objectclass=aixAccount
#pam_password clear

# Netscape SDK LDAPS
#ssl on

# Netscape SDK SSL options
#sslpath /etc/ssl/certs/cert7.db

# OpenLDAP SSL mechanism
# start_tls mechanism uses the normal LDAP port, LDAPS typically 636
ssl start_tls
#ssl on

# OpenLDAP SSL options
# Require and verify server certificate (yes/no)
# Default is to use libldap's default behavior, which can be configured in
# /etc/openldap/ldap.conf using the TLS_REQCERT setting.  The default for
# OpenLDAP 2.0 and earlier is "no", for 2.1 and later is "yes".
tls_checkpeer yes

# CA certificates for server certificate verification
# At least one of these are required if tls_checkpeer is "yes"
#tls_cacertfile /etc/ssl/ca.cert
tls_cacertfile /usr/local/etc/openldap/cacert.pem
#tls_cacertdir /etc/ssl/certs

# Seed the PRNG if /dev/urandom is not provided
#tls_randfile /var/run/egd-pool

# SSL cipher suite
# See man ciphers for syntax
#tls_ciphers TLSv1

# Client certificate and key
# Use these, if your server requires client authentication.
tls_cert /usr/local/etc/openldap/ny_sftpc1_servercrt.pem
tls_key /usr/local/etc/openldap/ny_sftpc1_serverkey.pem
# Disable SASL security layers. This is needed for AD.
#sasl_secprops maxssf=0

# Override the default Kerberos ticket cache location.
#krb5_ccname FILE:/etc/.ldapcache

# SASL mechanism for PAM authentication - use is experimental
# at present and does not support password policy control
#pam_sasl_mech DIGEST-MD5
 
OK, the first time I saw your post I didn't realize that the chroot you were referring to was the built-in chroot that OpenSSH offers and this is why I was asking you for your jail's setup. No problem, though, the info you sent might be useful either way.

From what I understand (by looking how OpenSSH's chrooting method works), you might need to copy some libraries and/or maybe some binaries/configs(?) inside the chroot's root directory, which on your case is /mnt. This means that you might need some folders like /mnt/lib or /mnt/usr/lib, etc to be present in your case. If I wanted to find which files are needed and are not present, I'd run sshd from the command line through ktrace(1) (with -d to follow descendants), and I'd filter kdump(1)'s output to show all open(2) system calls (using grep(1)) to see which ones fail and seem to be related to ldap/nss (and which will probably be located at the end of the file and also be repeating themselves).
 
Thanks. I also wanted to clarify that if I disable LDAP lookups, the SFTP chroot works fine without needing to copy additional files or libraries in to other areas of the chrooted area.

Once LDAP lookups are enabled I am still able to authenticate and access the SFTP chroot environment but the first time I execute the ls command there is a 20 minute pause. If I do copy a hosts file over the the chrooted envirnment there is no delay.

Below is a trace using LDAP only where the delay exists. I note in the trace where the 20 minute dealy is (let me know if you need to see more of the trace).

Code: 
      "sftp> "
 11896 sftp     RET   write 6
 11896 sftp     CALL  ioctl(0,TIOCGETA,0x288084d0)
 11896 sftp     RET   ioctl 0
 11896 sftp     CALL  ioctl(0,TIOCSETAW,0x288084a4)
 11896 sftp     RET   ioctl 0
 11896 sftp     CALL  read(0,0xbfbfe3ab,0x1)
 11896 sftp     GIO   fd 0 read 1 byte
       "g"
 11896 sftp     RET   read 1
 11896 sftp     CALL  write(0x1,0x28839000,0x1)
 11896 sftp     GIO   fd 1 wrote 1 byte
       "g"
 11896 sftp     RET   write 1
 11896 sftp     CALL  read(0,0xbfbfe3ab,0x1)
 11896 sftp     GIO   fd 0 read 1 byte
       0x0000 7f                                                                          |.|

 11896 sftp     RET   read 1
 11896 sftp     CALL  write(0x1,0x28839000,0x4)
 11896 sftp     GIO   fd 1 wrote 4 bytes
       0x0000 081b 5b4b                                                                   |..[K|

 11896 sftp     RET   write 4
 11896 sftp     CALL  read(0,0xbfbfe3ab,0x1)

=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=

20 minute pause here.  The the ls command completes.  Everything
works fine after the 20 minute pause

=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=
 11897 ssh      RET   read 1
 11897 ssh      CALL  read(0x4,0xbfbfd5af,0x1)
 11897 ssh      GIO   fd 4 read 1 byte
       "o"
 11897 ssh      RET   read 1
 11897 ssh      CALL  read(0x4,0xbfbfd5af,0x1)
 11897 ssh      GIO   fd 4 read 1 byte
       "g"
 11897 ssh      RET   read 1
 11897 ssh      CALL  read(0x4,0xbfbfd5af,0x1)
 11897 ssh      GIO   fd 4 read 1 byte
       "o"
 11897 ssh      RET   read 1
 11897 ssh      CALL  read(0x4,0xbfbfd5af,0x1)
 11897 ssh      GIO   fd 4 read 1 byte
       "
       "
 11897 ssh      RET   read 1
 11897 ssh      CALL  write(0x4,0x2838ed71,0x1)
 11897 ssh      GIO   fd 4 wrote 1 byte
 
Working good enough now

The issue goes away if I use DNS instead of host files. I created an A record for my LDAP server and there is no more delay. I thought that most services looked at the host file before reaching out to DNS, this may be one of those exceptions.

Thanks for taking the time to review this issue.
 
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