openssh: don't overwrite sshd_config unconditionally

The current implementation was overwriting the sshd_config and sshd
assuming PAM is needed by default

openssh should use the default sshd_config packaged with the component
if no distro specific needs are present and not overwrite the full
sshd_config file

1. If PAM is enabled as a distro then enable the UsePAM option in sshd_config
2. Moved the file sshd to pam directory so that when pam is enabled,
   then replace the default from poky by installing the same

Signed-off-by: Ranjitsinh Rathod <ranjitsinh.rathod@kpit.com>
Signed-off-by: Ranjitsinh Rathod <ranjitsinhrathod1991@gmail.com>
Signed-off-by: Joe MacDonald <joe@deserted.net>

recipes-connectivity/openssh/files/sshd_config

@@ -1,118 +0,0 @@
-#	$OpenBSD: sshd_config,v 1.102 2018/02/16 02:32:40 djm Exp $
-
-# This is the sshd server system-wide configuration file.  See
-# sshd_config(5) for more information.
-
-# This sshd was compiled with PATH=/usr/bin:/bin:/usr/sbin:/sbin
-
-# The strategy used for options in the default sshd_config shipped with
-# OpenSSH is to specify options with their default value where
-# possible, but leave them commented.  Uncommented options override the
-# default value.
-
-#Port 22
-#AddressFamily any
-#ListenAddress 0.0.0.0
-#ListenAddress ::
-
-#HostKey /etc/ssh/ssh_host_rsa_key
-#HostKey /etc/ssh/ssh_host_ecdsa_key
-#HostKey /etc/ssh/ssh_host_ed25519_key
-
-# Ciphers and keying
-#RekeyLimit default none
-
-# Logging
-#SyslogFacility AUTH
-#LogLevel INFO
-
-# Authentication:
-
-#LoginGraceTime 2m
-#PermitRootLogin prohibit-password
-#StrictModes yes
-#MaxAuthTries 6
-#MaxSessions 10
-
-#PubkeyAuthentication yes
-
-# The default is to check both .ssh/authorized_keys and .ssh/authorized_keys2
-# but this is overridden so installations will only check .ssh/authorized_keys
-#AuthorizedKeysFile	.ssh/authorized_keys
-
-#AuthorizedPrincipalsFile none
-
-#AuthorizedKeysCommand none
-#AuthorizedKeysCommandUser nobody
-
-# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
-#HostbasedAuthentication no
-# Change to yes if you don't trust ~/.ssh/known_hosts for
-# HostbasedAuthentication
-#IgnoreUserKnownHosts no
-# Don't read the user's ~/.rhosts and ~/.shosts files
-#IgnoreRhosts yes
-
-# To disable tunneled clear text passwords, change to no here!
-#PasswordAuthentication yes
-#PermitEmptyPasswords no
-
-# Change to yes to enable challenge-response passwords (beware issues with
-# some PAM modules and threads)
-ChallengeResponseAuthentication no
-
-# Kerberos options
-#KerberosAuthentication no
-#KerberosOrLocalPasswd yes
-#KerberosTicketCleanup yes
-#KerberosGetAFSToken no
-
-# GSSAPI options
-#GSSAPIAuthentication no
-#GSSAPICleanupCredentials yes
-
-# Set this to 'yes' to enable PAM authentication, account processing,
-# and session processing. If this is enabled, PAM authentication will
-# be allowed through the ChallengeResponseAuthentication and
-# PasswordAuthentication.  Depending on your PAM configuration,
-# PAM authentication via ChallengeResponseAuthentication may bypass
-# the setting of "PermitRootLogin without-password".
-# If you just want the PAM account and session checks to run without
-# PAM authentication, then enable this but set PasswordAuthentication
-# and ChallengeResponseAuthentication to 'no'.
-UsePAM yes
-
-#AllowAgentForwarding yes
-#AllowTcpForwarding yes
-#GatewayPorts no
-#X11Forwarding no
-#X11DisplayOffset 10
-#X11UseLocalhost yes
-#PermitTTY yes
-#PrintMotd yes
-#PrintLastLog yes
-#TCPKeepAlive yes
-#UseLogin no
-#PermitUserEnvironment no
-Compression no
-ClientAliveInterval 15
-ClientAliveCountMax 4
-#UseDNS no
-#PidFile /var/run/sshd.pid
-#MaxStartups 10:30:100
-#PermitTunnel no
-#ChrootDirectory none
-#VersionAddendum none
-
-# no default banner path
-#Banner none
-
-# override default of no subsystems
-Subsystem	sftp	/usr/libexec/sftp-server
-
-# Example of overriding settings on a per-user basis
-#Match User anoncvs
-#	X11Forwarding no
-#	AllowTcpForwarding no
-#	PermitTTY no
-#	ForceCommand cvs server

recipes-connectivity/openssh/openssh_%.bbappend

@@ -1 +1,15 @@
 require ${@bb.utils.contains('DISTRO_FEATURES', 'selinux', '${BPN}_selinux.inc', '', d)}
+
+# if pam feature is enabled in the distro then take sshd from the pam directory.
+FILESEXTRAPATHS_prepend := "${@bb.utils.contains('DISTRO_FEATURES', 'pam', '${THISDIR}/files/pam:', '', d)}"
+
+do_install_append(){
+
+    if [ "${@bb.utils.filter('DISTRO_FEATURES', 'pam', d)}" ]; then
+        # Make sure UsePAM entry is in the sshd_config file.
+        # If entry not present then append it.
+        grep -q 'UsePAM' "${D}/etc/ssh/sshd_config" && \
+        sed -i 's/.*UsePAM.*/UsePAM yes/' "${D}/etc/ssh/sshd_config" || \
+        echo 'UsePAM yes' >> "${D}/etc/ssh/sshd_config"
+    fi
+}