PAM Integration

== Motivation ==
For Yocto 1.1 we are working to ensure that PAM (Pluggable Authentication Module) support is consistent and enabled in recipes where it is applicable. 
== Build image ==
If you want to enable pam support, please add "pam" to DISTRO_FEATURES by add one line to build/conf/local.conf
 DISTRO_FEATURES_append += " pam"
Then add the packages to sato by apply this patch
 diff --git a/meta/recipes-sato/tasks/task-core-x11-sato.bb b/meta/recipes-sato/tasks/task-core-x11-sato.bb
 index 43b24d2..ea9fa14 100644
 --- a/meta/recipes-sato/tasks/task-core-x11-sato.bb
 +++ b/meta/recipes-sato/tasks/task-core-x11-sato.bb
 @@ -31,4 +31,11 @@ RDEPENDS_task-core-x11-sato = "\
 gtk-sato-engine \
 gthumb \
 x11vnc \
 - ${NETWORK_MANAGER}"
 + ${NETWORK_MANAGER} \
 + \
 + at \
 + cronie \
 + cups \
 + polkit \
 + screen \
 + shadow \
 + sudo "
openssh is conflict with dropbear. If you want to test openssh please uninstall dropbear first and then install openssh.
Then you can build the core-image-sato and test these packages on the sato image.
== Log files ==
We can test the packages both on core-image-sato and core-image-lsb
* on sato, edit the /etc/syslog.conf, set
 DESTINATION="file" 
then you can check the log via /var/log/message
* on lsb, the log information are send to /var/log/auth.log
== Common configure files ==
For convenience, list common configure files here:
common-auth
 auth	[success=1 default=ignore]	pam_unix.so nullok_secure
 auth	requisite			pam_deny.so
 auth	required			pam_permit.so
common-account
 account [success=1 new_authtok_reqd=done default=ignore] pam_unix.so 
 account requisite pam_deny.so
 account required pam_permit.so
common-password
 password [success=1 default=ignore] pam_unix.so obscure sha512
 password requisite pam_deny.so
 password required pam_permit.so
common-session
 session [default=1] pam_permit.so
 session requisite pam_deny.so
 session required pam_permit.so
 session required pam_unix.so 
common-session-noninteractive
 session [default=1] pam_permit.so
 session requisite pam_deny.so
 session required pam_permit.so
 session required pam_unix.so
== Recipes with PAM support ==
The following recipes are identified to have PAM support:
=== at === 
* Simple ways to verify 'at':
 $ at now
 $ echo "$msg_to_print" >> /tmp/at_test
 $ < ctrl+D >
 $ cat /tmp/at_test # Verify if the message has been there 
* /etc/pam.d/atd - not installed by default, copy it from source code and replace '@include' with appropriate 'module-type include':
 auth required pam_env.so
 auth include common-auth
 account include common-account
 session include common-session-noninteractive
 session required pam_limits.so
* test pam plugins
** pam_env.so
modify /etc/pam.d/atd
 auth required pam_env.so debug
modify /etc/security/pam_env.conf, add a test entry such as:
 MYNAME DEFAULT="test-at"
log in /var/log/auth.log:
 Jul 11 08:41:22 qemux86 atd[678]: pam_env(atd:setcred): pam_putenv("MYNAME=test-at")
** pam_limits.so
add line to /etc/security/limits.conf 
 root - nofile 3
'at' job failed, log in /var/log/auth.log:
 Jul 11 08:49:42 qemux86 atd[699]: pam_env(atd:setcred): Unable to open config file: /etc/security/pam_env.conf: Too many open files
modify the line:
 root - nofile 4
'at' job successed, log in /var/log/auth.log:
 Jul 11 08:59:59 qemux86 atd[738]: pam_unix(atd:session): session opened for user root by (uid=0) 
 Jul 11 08:59:59 qemux86 atd[738]: pam_unix(atd:session): session closed for user root
=== cronie ===
* /etc/pam.d/crond:
 account required pam_access.so
 account include common-password
 session required pam_loginuid.so
 session include common-session-noninteractive
 auth include common-auth
* test commands:
 crontab -e # establish a crontab jobs and check if it works
 crontab -l # list crontab jobs for current user
* test pam plugins
Verified, test ways and the logs/results please refer to other packages:
** pam_env.so
** pam_access.so
** pam_unix.so
** pam_permit.so
** pam_deny.so
** pam_loginuid.so
 TBD
=== cups ===
* /etc/pam.d/cups
 auth	 required	pam_unix.so shadow nodelay
 account required	pam_unix.so
* Modify /etc/cups/cupsd.conf:
 ...
 - Listen localhost:631
 + Port 631
 ...
 # Restrict access to the server... 
 <Location /> 
 Order allow,deny 
 + allow all 
 </Location>
 ...
 # Restrict access to the admin pages... 
 <Location /admin> 
 Order allow,deny 
 + allow all 
 </Location> 
 ...
* Test pam plugins
** pam_unix.so
Add debug option to '/etc/pam/cups':
 auth	 required	pam_unix.so shadow nodelay debug
 account required	pam_unix.so debug
Access the cups configure page via web browser:
 http://<qemu.ip>:631
Click 'Administration' -> 'Add Printer', start the pop-window for user authentication, input correct user and password:
 user: root
 pwd: <correct password>
Entry the 'Add Printer' configure page successed.
Input error password:
 user: root
 pwd: <error password>
Check log in '/var/log/cups/error_log':
 E [14/Jul/2011:02:41:26 +0800] cupsdAuthorize: pam_authenticate() returned 7 (Authentication failure)!
Modify '/etc/shadow':
 -root:$6$yMXdsttU$kT7A.n9bP0w0zzX6Uj1wmypHcq0lSGaC5/4xgNTZRSjNvW0q85ryBz8C6WNCbr22c6RjRKaVhv23ogrmoAo9m.:15168:0:99999:7:::
 +root:$6$yMXdsttU$kT7A.n9bP0w0zzX6Uj1wmypHcq0lSGaC5/4xgNTZRSjNvW0q85ryBz8C6WNCbr22c6RjRKaVhv23ogrmoAo9m.:15168:0:99999:7::1:
Repeat the user authentication steps, check log in '/var/log/cups/error_log':
 E [14/Jul/2011:03:05:00 +0800] cupsdAuthorize: pam_acct_mgmt() returned 13 (User account has expired)!
=== dropbear ===
* For supporting pam in dropbear, we need two steps:
* Add configuration "--enable-pam" 
* Add patches to open macro definition for supporting in option.h
 --- a/ptions.h 2011-07-12 11:32:34.165333202 +0800
 +++ b/options.h.new 2011-07-12 11:33:25.757332986 +0800
 @@ -149,9 +149,9 @@
 * but there's an interface via a PAM module - don't bother using it otherwise.
 * You can't enable both PASSWORD and PAM. */
 -#define ENABLE_SVR_PASSWORD_AUTH
 +//#define ENABLE_SVR_PASSWORD_AUTH
 /* PAM requires ./configure --enable-pam */
 -/*#define ENABLE_SVR_PAM_AUTH*/
 +#define ENABLE_SVR_PAM_AUTH
 #define ENABLE_SVR_PUBKEY_AUTH
 /* Wether to ake public key options in authorized_keys file into account */
* Test result(dropbear only support simple authentication, account and auth)
** Server(account)
 (server ip:192.168.7.2)
 $touch /etc/pam.d/sshd
 #%PAM-1.0
 account required pam_access.so
 $vi /etc/security/access.conf
 - : root : ALL
** Client
 $ssh username@server-ip
 (Disallow access)
** log information
 Jul 14 07:01:48 qemux86 dropbear[407]: pam_access(sshd:account): access denied for user `root' from `ssh'
 Jul 14 07:01:48 qemux86 dropbear[407]: pam_acct_mgmt() failed, rc=6, Permission denied 
 Jul 14 07:01:48 qemux86 dropbear[407]: bad PAM password attempt for 'root' from 192.168.7.1:33633
** Server(auth)
 $vi /etc/pam.d/sshd
 auth include common-auth
 $vi /etc/pam.d/common-auth
 #auth [success=1 default=ignore] pam_unix.so nullok_secure
 auth [success=0 default=ignore] pam_unix.so debug
 $ passwd -d username <blank password>
** Client
 $ssh username@server-ip
 (Disallow access)
** log information
 Jul 14 07:06:42 qemux86 dropbear[421]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost= user=yxf
 Jul 14 07:06:44 qemux86 dropbear[421]: pam_authenticate() failed, rc=7, Authentication failure 
 Jul 14 07:06:44 qemux86 dropbear[421]: bad PAM password attempt for 'yxf' from 192.168.7.1:379
=== openssh ===
* Absent configuration /etc/pam.d/sshd, we need to add patches. After adding this file, it can support pam function through simple test.
* Test Result
** Configuration of sshd
 auth include common-auth
 account required pam_nologin.so
 account include common-account
 password include common-password
 session optional pam_keyinit.so force revoke
 session include common-session
 session required pam_loginuid.so
** auth include common-auth --Server
 $echo 'UsePAM no' >>/etc/ssh/sshd_config
 $vi /etc/ssh/sshd_config
 PermitEmptyPasswords yes 
 Other is as same as sudo
** log information
 Jul 12 11:16:21 qemux86 sshd[650]: pam_unix(sshd:session): session opened for user test by (uid=0)
 
** account required pam_nologin.so --Server
 $touch /etc/nologin
** Client
 $ssh username@server-ip
 (Disallow accession)
** log information --Server
 Jul 13 01:43:48 qemux86 sshd[672]: Accepted keyboard-interactive/pam for yxf from 192.168.7.1 port 59877 ssh2
 Jul 13 01:43:48 qemux86 sshd[672]: fatal: PAM: pam_setcred(): Failure setting user credentia
** account include common-account --Server
 $vi /etc/ssh/sshd_config
 PermitEmptyPasswords no
 $vi /etc/pam.d/common-account 
 #account [success=1 new_authtok_reqd=done default=ignore] pam_unix.so
 account [success=0 new_authtok_reqd=done default=ignore] pam_unix.so
** Client
 $ssh username@server-ip
 (Disallow accession)
** log information
 Jul 13 02:11:24 qemux86 sshd[752]: Failed password for root from 192.168.7.1 port 53784 ssh2
** password include common-password
 $vi /etc/pam.d/common-password
 password [success=1 default=ignore] pam_unix.so obscure sha512 
 It's no use for sshd, So no test result for this item
** session optional pam_keyinit.so force revoke --Server
 No action
** Client
 $ssh username@server-ip
** log information
 Jul 13 07:28:18 qemux86 sshd[1132]: pam_keyinit(sshd:session): OPEN 1
 Jul 13 07:28:18 qemux86 sshd[1132]: pam_keyinit(sshd:session): UID:1000 [0] GID:1000 [0]
 Jul 13 07:28:18 qemux86 sshd[1132]: pam_keyinit(sshd:session): JOIN = 236576375
** Client( the same session as the above "client" )
 $exit
** log information
 Jul 13 07:34:47 qemux86 sshd[1132]: pam_keyinit(sshd:session): CLOSE 1,236576375,1
 Jul 13 07:34:47 qemux86 sshd[1132]: pam_keyinit(sshd:session): REVOKE 236576375
 Jul 13 07:34:47 qemux86 sshd[1132]: pam_keyinit(sshd:session): UID:1000 [0] GID:1000 [0]
** session include common-session --Server
 $vi /etc/pam.d/common-session
 #session [default=1] pam_permit.so
 session [default=0] pam_permit.so
** Client
 $ssh username@server-ip
 (Disallow accession)
** log information
 Jul 13 05:53:35 qemux86 sshd[960]: error: PAM: pam_open_session(): Permission denied
 Jul 13 05:53:35 qemux86 sshd[960]: Received disconnect from 192.168.7.1: 11: disconnected by user
** session required pam_loginuid.so --Server(Record user´s login uid to the process attribute)
 No action
** Client
 $ssh username@server-ip
** log information
 Jul 13 06:31:32 qemux86 sshd[1028]: pam_warn(sshd:session): function=[pam_sm_open_session] service=[sshd] terminal=[ssh] user=[yxf] ruser= [<unknown>] rhost=[ubuntuwindriver.local] 
 Jul 13 06:31:32 qemux86 sshd[1028]: pam_unix(sshd:session): session opened for user yxf by (uid=0)
=== polkit ===
Polkit includes four binaries. Only pkexec depends on pam. So I use pkexec to make pam test.
Pkexec allows an authorized user to execute PROGRAM as another user. If username is not specified, then the program will be executed as the administrative super user, root.
* Pam configuration file of polkit 
 %PAM-1.0
 auth include common-auth
 account include common-account
 password include common-password
 session include common-session
* Test Reult
** Normally pkexec can call pam modules from the above configuration file
 $ pkexec cat /var/log/auth.log 
 ==== AUTHENTICATING FOR org.freedesktop.policykit.exec ===
 Authentication is needed to run `/bin/cat' as the super user
 Authenticating as: root
 Password: <---Input root password and press key "Enter"
 
 Jul 14 22:13:18 emenlow polkitd(authority=local): Registered Authentication Agent for unix-process:2466:778527 (system bus name :1.10 [pkexec cat /var/log/auth.log], 
 object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8)
 Jul 14 22:13:18 emenlow polkit-agent-helper-1[2501]: PAM pam_parse: expecting non-zero; [... default=ignore]
 Jul 14 22:13:18 emenlow polkit-agent-helper-1[2501]: PAM pam_parse: expecting non-zero; [... default=ignore]
 Jul 14 22:13:21 emenlow polkitd(authority=local): Unregistered Authentication Agent for unix-process:2466:778527 (system bus name :1.10,
 object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8) (disconnected from bus)
 Jul 14 22:13:21 emenlow polkitd(authority=local): Operator of unix-process:2466:778527 FAILED to authenticate to gain authorization for action
 org.freedesktop.policykit.exec for unix-process:2466:778527 [sh] (owned by unix-user:yxf)
 Jul 14 22:14:37 emenlow polkitd(authority=local): Registered Authentication Agent for unix-process:2466:778527 (system bus name :1.11 [pkexec 
 cat /var/log/auth.log], object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8)
 Jul 14 22:16:08 emenlow polkitd(authority=local): Operator of unix-process:2466:778527 successfully authenticated as unix-user:root to gain 
 ONE-SHOT authorization for action org.freedesktop.policykit.exec for unix-process:2466:778527 [sh] (owned by unix-user:yxf)
 Jul 14 22:16:08 emenlow pkexec: pam_unix(polkit-1:session): session opened for user root by root(uid=500)
 Jul 14 22:16:08 emenlow pkexec[2507]: yxf: Executing command [USER=root] [TTY=/dev/pts/0] [CWD=/] [COMMAND=/bin/cat /var/log/auth.log]
 Jul 14 22:16:08 emenlow polkitd(authority=local): Unregistered Authentication Agent for unix-process:2466:778527 (system bus name :1.11, 
 object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8) (disconnected from bus)
** auth include common-auth
 $vi /etc/pam.d/common-auth
 #auth [success=1 default=ignore] pam_unix.so nullok_secure
 auth [success=0 default=ignore] pam_unix.so nullok_secure
 $ pkexec cat /var/log/auth.log 
 ==== AUTHENTICATING FOR org.freedesktop.policykit.exec ===
 Authentication is needed to run `/bin/cat' as the super user
 Authenticating as: root
 Password: 
 polkit-agent-helper-1: pam_authenticate failed: Permission denied
 Error: Permission denied
 ==== AUTHENTICATION FAILED ===
 Error executing command as another user: Not authorized
 
 This incident has been reported.
log information in /var/log/auth.log
 Jul 14 22:23:24 emenlow pkexec[2515]: yxf: Error executing command as another user: Not authorized [USER=root] [TTY=/dev/pts/0] [CWD=/] [COMMAND=/bin/cat /var/log/auth.log]
** account include common-account
 $ vi /etc/pam.d/common-account
 #account [success=1 new_authtok_reqd=done default=ignore] pam_unix.so
 account [success=0 new_authtok_reqd=done default=ignore] pam_unix.so
 $ pkexec cat /var/log/auth.log 
 ==== AUTHENTICATING FOR org.freedesktop.policykit.exec ===
 Authentication is needed to run `/bin/cat' as the super user
 Authenticating as: root
 Password: 
 polkit-agent-helper-1: pam_acct_mgmt failed: Permission denied
 Error: Permission denied
 ==== AUTHENTICATION FAILED ===
 Error executing command as another user: Not authorized
log information in /var/log/auth.log
 Jul 14 22:29:12 emenlow pkexec[2523]: yxf: Error executing command as another user: Not authorized [USER=root] [TTY=/dev/pts/0] [CWD=/] [COMMAND=/bin/cat /var/log/auth.log]
** password include common-password
 It is no use for polkit. So I don't test it
** session include common-session
 $ vi /etc/pam.d/common-session
 #session [default=1] pam_permit.so
 session [default=0] pam_permit.so
 $ pkexec cat /var/log/auth.log 
 ==== AUTHENTICATING FOR org.freedesktop.policykit.exec ===
 Authentication is needed to run `/bin/cat' as the super user
 Authenticating as: root
 Password: 
 ==== AUTHENTICATION COMPLETE ===
 pam_open_session() failed: Permission denied
log information in /var/log/auth.log
 Jul 14 22:35:51 emenlow polkitd(authority=local): Unregistered Authentication Agent for unix-process:2466:778527 (system bus name :1.17, 
 object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8)
=== screen ===
screen use pam to authenticate users during unlock terminal. Its configure file screen comes from Fedora and replace system-auth with common-auth
 #%PAM-1.0
 auth include common-auth
First start screen:
 root@qemux86:/etc/pam.d# screen
it will show some information about screen, just press Space or Enter and it will give a screen terminal:
 root@qemux86:/etc/pam.d# 
then press "Ctrl+a x" will lock the screen terminal and show:
 
 Screen used by root <root>.
 Password:
In another root terminal, clear the root's password:
 password -d root
modify one line in common-auth
 auth	[success=1 default=ignore]	pam_unix.so nullok_secure
with
 auth	[success=1 default=ignore]	pam_unix.so debug
option nullok_secure will allow users who has blank password login, after remove it these users are not allowed to login.
Back to the screen terminal, press <Enter>(because root's password is blank now) will fail: 
 Screen used by root <root>.
 Password:
 Screen used by root <root>.
 Password:
then modify the line in common-auth with 
 auth	[success=1 default=ignore]	pam_unix.so nullok_secure debug
On the screen terminal press <Enter> again it unlock the terminal.
the log in /var/log/auth.log:
 Jul 11 14:14:14 qemux86 screen: pam_unix(screen:auth): authentication failure; logname=root uid=0 euid=0 tty= ruser= rhost= user=root
=== shadow ===
==== chage ====
/etc/pam.d/chage: replace system-auth with common-password
 #%PAM-1.0
 auth		sufficient	pam_rootok.so
 account	required	pam_permit.so
 password	include		common-auth(common-password)
* test pam_rootok.so
add the only option for pam_rootok.so
 auth		sufficient	pam_rootok.so debug
run command chage as root:
 root@qemux86:/etc/pam.d# chage -m 10 test
log info in /var/log/message shows pam_rootok.so return success:
 Jul 12 06:55:18 qemux86 authpriv.debug chage[575]: pam_rootok(chage:auth): root check succeeded
 Jul 12 06:55:18 qemux86 authpriv.info chage[575]: changed password expiry for test
* pam_unix.so
The password component of pam_unix.so performs the task of updating the user´s password. And chage changes user password expiry information.
No test point.
==== chfn ====
/etc/pam.d/chfn
 auth	 sufficient	pam_rootok.so
 auth include common-auth
 account include common-account
 session include common-session
add option debug to pam_rootok.so
 auth	 sufficient	pam_rootok.so debug
* pam_rootok.so
run command chfn as root:
 root@qemux86:/etc/pam.d# chfn -f testyayay test
log info in /var/log/message shows pam_rootok.so return success:
 Jul 12 07:22:59 qemux86 authpriv.debug chfn[638]: pam_rootok(chfn:auth): root check succeeded
 Jul 12 07:22:59 qemux86 authpriv.info chfn[638]: changed user 'test' information
* pam_unix.so
the content of common-auth are shown at section "Common configure files"
comment the configure file chfn pam_rootok.so line, because it will make pam return success:
 #auth		sufficient	pam_rootok.so
and modify the pam_unix.so line in common-auth to remove nullok_secure:
 auth	[success=1 default=ignore]	pam_unix.so debug
run commands:
 root@qemux86:/etc/pam.d# passwd -d root 
 root@qemux86:/etc/pam.d# chfn -f testself test # test is a unprivileged user
 Password: 
 chfn: PAM authentication failed
log in /var/log/message:
 Jul 12 07:53:16 qemux86 authpriv.notice chfn[673]: pam_unix(chfn:auth): authentication failure; logname=root uid=0 euid=0 tty= ruser= rhost= user=root
==== chgpasswd ====
/etc/pam.d/chgpasswd(need patch)
 #%PAM-1.0
 auth		sufficient	pam_rootok.so
 account	required	pam_permit.so
 password	include		system-auth
test pam_rootok.so and pam_unix.so(common-password) refer to test steps in chfn
==== chpasswd ====
/etc/pam.d/chpasswd
 password include common-password
common-password are listed before, we remove the pam_unix.so option nullok_secure and add audit:
 password	[success=1 default=ignore]	pam_unix.so audit
commands to test:
 root@qemux86:/etc/pam.d# chpasswd
 test:
 Press Ctrl+d, the follow are terminal output:
 No password supplied
 No password supplied
 No password supplied
 chpasswd: (user test) pam_chauthtok() failed, error:
 Authentication token manipulation error
 chpasswd: (line 1, user test) password not changed
syslog info:
 Jul 15 04:53:39 qemux86 authpriv.notice chpasswd[844]: pam_warn(chpasswd:auth): function=[pam_sm_authenticate] service=[chpasswd] terminal=[<unknown>] user=[root] ruser=[<unknown>] rhost=[<unknown>]
 Jul 15 04:53:39 qemux86 authpriv.notice chpasswd[844]: pam_warn(chpasswd:account): function=[pam_sm_acct_mgmt] service=[chpasswd] terminal=[<unknown>] user=[root] ruser=[<unknown>] rhost=[<unknown>]
 Jul 15 04:53:41 qemux86 authpriv.debug chpasswd[844]: pam_unix(chpasswd:chauthtok): username [test] obtained
 Jul 15 04:53:41 qemux86 authpriv.debug chpasswd[844]: pam_unix(chpasswd:chauthtok): username [test] obtained
 Jul 15 04:53:41 qemux86 authpriv.debug chpasswd[844]: pam_unix(chpasswd:chauthtok): bad authentication token
 Jul 15 04:53:41 qemux86 authpriv.debug chpasswd[844]: pam_unix(chpasswd:chauthtok): bad authentication token
 Jul 15 04:53:41 qemux86 authpriv.debug chpasswd[844]: pam_unix(chpasswd:chauthtok): bad authentication token
 Jul 15 04:53:41 qemux86 authpriv.notice chpasswd[844]: pam_unix(chpasswd:chauthtok): new password not acceptable
==== chsh ====
/etc/pam.d/chsh
 auth required pam_shells.so
 auth sufficient pam_rootok.so
 auth include common-auth
 account include common-account
 session include common-session
* pam_shells.so
pam_shells only allows access to the system if the users shell is listed in /etc/shells. It also checks if /etc/shells is a plain file and not world writable.
check /etc/shells first:
 qemux86:~$ ls -l /etc/shells 
 -rw-r--r-- 1 root root 109 Jul 12 06:05 /etc/shells
 qemux86:~$ cat /etc/shells
 # /etc/shells: valid login shells
 /bin/sh
 /bin/ash
 /bin/bash
 /bin/dash
 /bin/ksh
 /usr/bin/ksh
 /usr/bin/screen
 qemux86:~$ 
login as a unprivileged user, the correct process is:
 qemux86:~$ chsh -s /bin/ash
 Password: <-- Enter password here
 qemux86:~$ 
syslog info:
 Jul 15 06:15:18 qemux86 authpriv.debug chsh[1283]: pam_rootok(chsh:auth): root check failed
 Jul 15 06:15:21 qemux86 authpriv.info chsh[1283]: changed user 'test' shell to '/bin/ash'
now remove /bin/ash from /etc/shells, then run the same command:
 qemux86:~$ chsh -s /bin/ash
 Password: <-- Enter password here
 chsh: /bin/ash is an invalid shell.
 qemux86:~$ 
if you make /etc/shells is writable to all people, chsh will fail with syslog info:
 Jul 15 05:38:38 qemux86 authpriv.err chsh[1091]: pam_shells(chsh:auth): /etc/shells is either world writable or not a normal file
* pam_rootok.so
modify pam_rootok.so item:
 auth required pam_rootok.so debug
then unprivileged users can't change their shell.
 qemux86:~$ chsh -s /bin/ash
 Password: 
 chsh: PAM authentication failed
 qemux86:~$ 
syslog info:
 Jul 15 06:43:14 qemux86 authpriv.debug chsh[1350]: pam_rootok(chsh:auth): root check failed
* pam_unix.so
**pam_unix in common-auth: please refer to sudo tests
**pam_unix in common-account and common-password don't have test point.
==== groupadd ====
/etc/pam.d/groupadd:
 #%PAM-1.0
 auth sufficient pam_rootok.so
 account required pam_permit.so
 password include system-auth(common-password)
* pam_rootok
please refer to chfn tests
*pam_unix.so in common-password doesn't has test point
==== groupdel ====
/etc/pam.d/groupdel(need patch)
 #%PAM-1.0
 auth sufficient pam_rootok.so
 account required pam_permit.so
 password include system-auth(common-password)
* pam_rootok
please refer to chfn tests
==== groupmems ====
/etc/pam.d/groupmems
 #%PAM-1.0
 auth sufficient pam_rootok.so
 account required pam_permit.so
 password include system-auth(common-password)
*pam_rootok:
refer to chfn tests
*pam_unix in common-password doesn't has test point
==== groupmod ====
/etc/pam.d/groupmod
 #%PAM-1.0
 auth sufficient pam_rootok.so
 account required pam_permit.so
 password include common-password
* pam_rootok
refer to chfn tests
* pam_unix in common-password
no test point
==== login ====
/etc/pam.d/login
 auth optional pam_faildelay.so delay=3000000
 auth [success=ok ignore=ignore user_unknown=ignore default=die] pam_securetty.so
 auth requisite pam_nologin.so
 session required pam_env.so readenv=1
 session required pam_env.so readenv=1 envfile=/etc/default/locale
 auth include common-auth
 auth optional pam_group.so
 session required pam_limits.so 
 session optional pam_lastlog.so 
 session optional pam_motd.so 
 session optional pam_mail.so standard 
 
 account include common-account 
 password include common-password 
 session include common-session
* pam_faildelay
this plugin an be used to set the delay on failure per-application. We increase "delay" to make it more obviously
 auth optional pam_faildelay.so delay=10000000
run login as root:
 root@qemux86:~# login
 qemux86 login: root
 Password: <-- enter a wrong password here, then will wait for 10 seconds to show next "login:"
 
 Login incorrect
 qemux86 login: 
syslog info:
 Jul 17 07:22:17 qemux86 authpriv.notice login[2223]: pam_unix(login:auth): authentication failure; logname=root uid=0 euid=0 tty=/dev/pts/2 ruser= rhost= user=root
 Jul 17 07:22:26 qemux86 authpriv.notice login[2223]: FAILED LOGIN (1) on '/dev/pts/2' FOR 'root', Authentication failure
* pam_securetty
pam_securetty allows root logins only if the user is logging in on a "secure" tty, as defined by the listing in /etc/securetty.
test steps:
 # ssh to yocto linux
 $ ssh root@192.168.7.2
 root@qemux86:~# tty 
 /dev/pts/1
 root@qemux86:~# login
 qemux86 login: root
 <-- don't ask for password, failed directly 
 Login incorrect
 qemux86 login: 
syslog info
 Jul 17 07:52:32 qemux86 authpriv.warn login[2341]: pam_securetty(login:auth): access denied: tty 'pts/1' is not secure !
 Jul 17 07:52:35 qemux86 authpriv.notice login[2341]: FAILED LOGIN (1) on '/dev/pts/1' FOR 'root', Authentication failure
Then add "pts/1" to file /etc/securetty, run commonds:
 root@qemux86:~# login
 qemux86 login: root
 Password: 
 Last login: Sun Jul 17 07:52:21 UTC 2011 from k-desktop.local on pts/1
 root@qemux86:~# 
syslog info
 Jul 17 07:56:00 qemux86 authpriv.notice login[2348]: ROOT LOGIN on '/dev/pts/1'
* pam_nologin
pam_nologin prevents non-root users from logging into the system when /etc/nologin exists. 
test steps
 root@qemux86:~# ls /etc/nologin
 ls: /etc/nologin: No such file or directory
 root@qemux86:~# login
 qemux86 login: test
 Last login: Sun Jul 17 07:19:24 UTC 2011 on pts/2
 qemux86:~$ logout
 root@qemux86:~# touch /etc/nologin
 root@qemux86:~# login
 qemux86 login: test
 
 
 Login incorrect
 qemux86 login: 
syslog info
 Jul 17 08:08:07 qemux86 authpriv.info login[2366]: pam_unix(login:session): session opened for user test by root(uid=0)
 Jul 17 08:08:08 qemux86 authpriv.info login[2366]: pam_unix(login:session): session closed for user test
 Jul 17 08:08:51 qemux86 authpriv.notice login[2371]: FAILED LOGIN (1) on '/dev/pts/1' FOR 'test', Authentication failure
* pam_env
refer to su tests
* pam_unix in common-auth
refer to chfn tests
* pam_group
pam_group grants group memberships to the user. Its configure file is /etc/security/group.conf.
First get your current tty by run
 root@qemux86:/etc/pam.d# tty
 /dev/pts/2
 root@qemux86:/etc/pam.d# 
then add a item to /etc/security/group.conf
 login; pts/* ;%root;Al0000-2400;plugdev,test 
'''
after that run commands
 root@qemux86:/etc/pam.d# id
 uid=0(root) gid=0(root) groups=0(root)
 root@qemux86:/etc/pam.d# login
 qemux86 login: root
 
 Password: 
 Last login: Mon Jul 18 00:20:47 UTC 2011 on pts/2
 root@qemux86:~# id
 uid=0(root) gid=0(root) groups=0(root),46(plugdev),1001(test)
 root@qemux86:~#
* pam_limits
pam_limits sets limits on the system resources that can be obtained in a user-session. 
Its default configure file is /etc/security/limits.conf, modify it with
 test - maxlogins 1
Login unprivileged user "test"
 root@qemux86:/etc/pam.d# login
 qemux86 login: test
 Last login: Sun Jul 17 08:08:07 UTC 2011 on pts/1
 qemux86:~$ 
And login in another terminal
 root@qemux86:~# login
 qemux86 login: test
 Too many logins for 'test'.
 Last login: Mon Jul 18 01:21:54 UTC 2011 on pts/2
 
 Permission denied
syslog info:
 Jul 18 01:39:55 qemux86 authpriv.debug login[2668]: pam_limits(login:session): reading settings from '/etc/security/limits.conf'
 Jul 18 01:39:55 qemux86 authpriv.debug login[2668]: pam_limits(login:session): process_limit: processing - maxlogins 1 for USER
 Jul 18 01:39:55 qemux86 authpriv.debug login[2668]: pam_limits(login:session): checking logins for 'test' (maximum of 1)
 Jul 18 01:39:55 qemux86 authpriv.warn login[2668]: pam_limits(login:session): Too many logins (max 1) for test
 Jul 18 01:39:55 qemux86 authpriv.info login[2668]: pam_unix(login:session): session opened for user test by root(uid=0)
 Jul 18 01:39:55 qemux86 authpriv.err login[2668]: Permission denied
* pam_lastlog
pam_lastlog is to display date of last login.
add options to pam_lastlog
 session optional pam_lastlog.so debug nodate
run commands and you can check that no last login date information shows
 root@qemux86:~# login
 qemux86 login: test
 Last login: on pts/2
 qemux86:~$
* pam_motd
pam_motd can be used to display arbitrary motd (message of the day) files after a successful login. By default the /etc/motd file is shown.
test steps:
 root@qemux86:~# cat /etc/motd
 root@qemux86:~# echo "Welcome to Yocto" > /etc/motd
 root@qemux86:~# login
 qemux86 login: root
 Password: 
 Last login: on pts/1
 Welcome to Yocto
 root@qemux86:~#
* pam_mail
refer to su tests
==== newusers ====
/etc/pam.d/newusers
 password include common-password
*pam_unix
modify the pam_unix item in common-password
 password [success=1 default=ignore] pam_unix.so debug 
run command:
 root@qemux86:~# newusers
 a::::::[Press key Enter]
 [Press Ctrl+d]
 No password supplied
 No password supplied
 No password supplied
 newusers: (user a) pam_chauthtok() failed, error:
 Authentication token manipulation error
 newusers: (line 1, user a) password not changed
syslog info:
 Jul 15 09:50:17 qemux86 authpriv.debug newusers[1560]: pam_unix(newusers:chauthtok): username [a] obtained
 Jul 15 09:50:17 qemux86 authpriv.debug newusers[1560]: pam_unix(newusers:chauthtok): username [a] obtained
 Jul 15 09:50:17 qemux86 authpriv.debug newusers[1560]: pam_unix(newusers:chauthtok): bad authentication token
 Jul 15 09:50:17 qemux86 authpriv.debug newusers[1560]: pam_unix(newusers:chauthtok): bad authentication token
 Jul 15 09:50:17 qemux86 authpriv.debug newusers[1560]: pam_unix(newusers:chauthtok): bad authentication token
 Jul 15 09:50:17 qemux86 authpriv.notice newusers[1560]: pam_unix(newusers:chauthtok): new password not acceptable
==== passwd ====
/etc/pam.d/passwd
 password include common-password
* pam_unix in common-password
modify the item to make password length not less than 4 characters:
 password [success=1 default=ignore] pam_unix.so minlen=4 debug
run test commands:
 qemux86:~$ passwd
 Changing password for test.
 (current) UNIX password: <-- input 123 here
 Enter new UNIX password: 
 Retype new UNIX password: 
 You must choose a longer password
 Enter new UNIX password: <-- input 1234 here
 Retype new UNIX password: 
 passwd: password updated successfully
 qemux86:~$ 
syslog doesn't has detail informatiaon
 Jul 17 02:00:39 qemux86 authpriv.debug passwd[1649]: pam_unix(passwd:chauthtok): username [test] obtained
 Jul 17 02:00:41 qemux86 authpriv.debug passwd[1649]: pam_unix(passwd:chauthtok): username [test] obtained
 Jul 17 02:00:49 qemux86 authpriv.notice passwd[1649]: pam_unix(passwd:chauthtok): password changed for test
==== su ====
/etc/pam.d/su
 auth sufficient pam_rootok.so
 session required pam_env.so readenv=1
 session required pam_env.so readenv=1 envfile=/etc/default/locale
 session optional pam_mail.so nopen
 auth include common-auth
 account include common-account
 session include common-session
* pam_rootok
refer to chfn tests
* pam_env
option readenv=1 means read configure file pointed by variable envfile, default is /etc/environment
We will add a variable named YOCTO to /etc/environment.
First we will check there is no var YOCTO after su
 root@qemux86:~# su test
 test@qemux86:/home/root$ echo $YOCTO
 test@qemux86:/home/root$ 
after add YOCTO=yoctolinux to /etc/environment, then test again
 root@qemux86:~# su test
 test@qemux86:/home/root$ echo $YOCTO
 yoctolinux
 test@qemux86:/home/root$ 
* pam_mail
The mailx in Yocto can NOT run correctly, so didn't test it. 
Test steps should be as follows. 
First remove option nopen which prevents show user mails
 #session optional pam_mail.so nopen
 session optional pam_mail.so 
Then mail a user, such as root(run test on Fedora 14)
 [packager@F14 ~]$ mail root
 Subject: test
 test
 EOT
 [packager@F14 ~]$ export LANG=C
 [packager@F14 ~]$ su -
 Password: 
 You have old mail in folder /var/mail/root.
 [root@F14 ~]#
* pam_unix in common-auth
refer to chfn tests
* pam_unix in common-account/common-session has no test point
==== useradd ====
/etc/pam.d/useradd(need patch)
 #%PAM-1.0
 auth sufficient pam_rootok.so
 account required pam_permit.so
 password include system-auth(common-password)
* pam_rootok
refer to chfn tests
* pam_unix in common-password:
no test point
==== userdel ====
/etc/pam.d/userdel(need patch)
 #%PAM-1.0
 auth sufficient pam_rootok.so
 account required pam_permit.so
 password include system-auth(common-password)
* pam_rootok
refer to chfn tests
* pam_unix in common-password: 
no test point
==== usermod ==== 
/etc/pam.d/usermod(need patch)
 #%PAM-1.0
 auth sufficient pam_rootok.so
 account required pam_permit.so
 password include system-auth(common-password)
* pam_rootok
refer to chfn tests
* pam_unix in common-password
no test point
=== sudo ===
*/etc/pam.d/sudo comes from Fedora, and replace system-auth with common-auth
 #%PAM-1.0
 auth include common-auth
 account include common-account
 password include common-password
 session required pam_keyinit.so revoke
 session required pam_limits.so
and content of common-auth has been show above.
*test pam plugins
**pam_unix.so
modify common-auth:
 auth [success=1 default=ignore] pam_unix.so debug
then unpriviledge user can NOT run sudo with blank password
 qemux86:~$ sudo rm /test
 Password:
 Sorry, try again.
 Password:
 Sorry, try again.
 Password:
 Sorry, try again.
 sudo: 3 incorrect password attempts
 qemux86:~$ sudo rm /test
 qemux86:~$
log in /var/log/auth.log:
 Jul 8 16:39:04 qemux86 sudo: pam_unix(sudo:auth): authentication failure; logname=test-pam uid=0 euid=0 tty=/dev/pts/1 ruser=test-pam rhost= user=test-pam
 Jul 8 16:39:14 qemux86 sudo: test-pam : 3 incorrect password attempts ; TTY=pts/1 ; PWD=/home/test-pam ; USER=root ; COMMAND=/bin/rm /test
 Jul 8 16:39:31 qemux86 sudo: pam_warn(sudo:account): function=[pam_sm_acct_mgmt] service=[sudo] terminal=[/dev/pts/1] user=[test-pam] ruser=[test-pam] rhost=[<unknown>]
 Jul 8 16:39:31 qemux86 sudo: test-pam : TTY=pts/1 ; PWD=/home/test-pam ; USER=root ; COMMAND=/bin/rm /test
**pam_deny.so
mv line
 auth requisite pam_deny.so
to the head of file, unprivilege user can NOT sudo any more:
 qemux86:~$ sudo rm /test
 Sorry, try again.
 Sorry, try again.
 Sorry, try again.
 sudo: 3 incorrect password attempts
 qemux86:~$
log in /var/log/auth.log:
 Jul 7 14:03:29 qemux86 sudo: test-pam : 3 incorrect password attempts ; TTY=pts/1 ; PWD=/home/test-pam ; USER=root ; COMMAND=/bin/rm /test
**pam_permit.so
comment this line
 auth required pam_permit.so
sudo will fail without ask user to enter password:
 qemux86:~$ sudo rm /test
 Sorry, try again.
 Sorry, try again.
 Sorry, try again.
 sudo: 3 incorrect password attempts
 qemux86:~$
log in /var/log/auth.log:
 Jul 7 12:43:22 qemux86 sudo: test-pam : 3 incorrect password attempts ; TTY=pts/1 ; PWD=/home/test-pam ; USER=root ; COMMAND=/bin/rm -f /test
**pam_limits.so
add line to /etc/security/limits.conf
 * - nofile 3
then sudo will fail:
 qemux86:~$ sudo rm /test
 Inconsistency detected by ld.so: dl-deps.c: 622: _dl_map_object_deps: Assertion `nlist > 1' failed!
modify the line:
 * - nofile 4
 qemux86:~$ sudo rm /test
 qemux86:~$
log in /var/log/auth.log:
 Jul 8 14:24:41 qemux86 sudo: pam_warn(sudo:account): function=[pam_sm_acct_mgmt] service=[sudo] terminal=[/dev/pts/1] user=[test-pam] ruser=[test-pam] rhost=[<unknown>]
 Jul 8 14:24:41 qemux86 sudo: test-pam : TTY=pts/1 ; PWD=/home/test-pam ; USER=root ; COMMAND=/bin/rm /test
 Jul 8 14:24:41 qemux86 sudo: pam_limits(sudo:session): reading settings from '/etc/security/limits.conf'
 Jul 8 14:24:41 qemux86 sudo: pam_limits(sudo:session): process_limit: processing - nofile 3 for DEFAULT
 Jul 8 14:24:50 qemux86 sudo: test-pam : TTY=pts/1 ; PWD=/home/test-pam ; USER=root ; COMMAND=/bin/rm /test
 Jul 8 14:24:50 qemux86 sudo: pam_limits(sudo:session): reading settings from '/etc/security/limits.conf'
 Jul 8 14:24:50 qemux86 sudo: pam_limits(sudo:session): process_limit: processing - nofile 4 for DEFAULT
** pam_keyinit
add option debug
 session optional pam_keyinit.so revoke debug
log shows pam_keyinit was called:
 Jul 7 14:13:39 qemux86 sudo: pam_warn(sudo:account): function=[pam_sm_acct_mgmt] service=[sudo] terminal=[/dev/pts/1] user=[test-pam] ruser=[test-pam] rhost=[<unknown>]
 Jul 7 14:13:39 qemux86 sudo: test-pam : TTY=pts/1 ; PWD=/home/test-pam ; USER=root ; COMMAND=/bin/rm /test
 Jul 7 14:13:39 qemux86 sudo: pam_keyinit(sudo:session): OPEN 1
 Jul 7 14:13:39 qemux86 sudo: pam_keyinit(sudo:session): UID:0 [0] GID:0 [1000]
 Jul 7 14:13:39 qemux86 sudo: pam_keyinit(sudo:session): GET SESSION = 143761918
 Jul 7 14:13:39 qemux86 sudo: pam_keyinit(sudo:session): GET SESSION = 669161571
according the source code pam_keyinit.c line 102 in function init_keyrings, the module return PAM_SUCCESS
== Identify upstream PAM patches to use ==
After checking the Fedora develop repository, the following packages may need patches(only libpam need to upgrade, other patches are pam related configure file but they are absent in poky):
* libpam: need update from current 1.1.3 to 1.1.4 Release Notes
* sudo: package sudo in Fedora provides /etc/pam.d/sudo and /etc/pam.d/sudo-i
** /etc/pam.d/sudo (Yocto use common-auth instead of system-auth)
 #%PAM-1.0
 auth include system-auth
 account include system-auth
 password include system-auth
 session optional pam_keyinit.so revoke
 session required pam_limits.so
* screen: check Fedora screen.pam
* util-linux: check Fedora source file util-linux-remote.pamd
* at: check Fedora util-linux-remote.pamd
* cups: check Fedora cups-1.1.16-system-auth.patch
* openssh: check Fedora sshd.pam
== PAM Unit Tests==
We use unit test cases provided by libpam itself, a subdirectory with name "xtests" under libpam source code. Right now we spit it as a sub-package libpam-xtests. After "bitbake libpam" you can find it under deploy directory. And it requires some packages:
 pam-plugin-debug 
 pam-plugin-access 
 pam-plugin-cracklib 
 pam-plugin-time 
 pam-plugin-pwhistory 
 pam-plugin-succeed-if 
All test cases are:
 tst-pam_dispatch1 tst-pam_dispatch2 tst-pam_dispatch3 \
 tst-pam_dispatch4 tst-pam_dispatch5 \
 tst-pam_cracklib1 tst-pam_cracklib2 \
 tst-pam_unix1 tst-pam_unix2 tst-pam_unix3 tst-pam_unix4 \
 tst-pam_access1 tst-pam_access2 tst-pam_access3 \
 tst-pam_access4 tst-pam_limits1 tst-pam_succeed_if1 \
 tst-pam_group1 tst-pam_authfail tst-pam_authsucceed \
 tst-pam_pwhistory1 tst-pam_time1
On build machine after install package libpam-xtests, go to the xtexts directory and run tests
 export ALL_TESTS="tst-pam_dispatch1 tst-pam_dispatch2 tst-pam_dispatch3 \
 tst-pam_dispatch4 tst-pam_dispatch5 \
 tst-pam_cracklib1 tst-pam_cracklib2 \
 tst-pam_unix1 tst-pam_unix2 tst-pam_unix3 tst-pam_unix4 \
 tst-pam_access1 tst-pam_access2 tst-pam_access3 \
 tst-pam_access4 tst-pam_limits1 tst-pam_succeed_if1 \
 tst-pam_group1 tst-pam_authfail tst-pam_authsucceed \
 tst-pam_pwhistory1 tst-pam_time1"
 cd /usr/share/Linux-PAM/xtests
 ./run-xtests.sh `pwd` $ALL_TESTS
If you want to run sigle test case, just run (take tst-pam_time1 for example)
 ./run-xtests.sh . tst-pam_time1
Two unit tests may NOT passed, they need some prerequisite:
* tst-pam_cracklib1
* tst-pam_cracklib2
**need /lib/security/pam_cracklib.so, need build cracklib first, and then libpam will check it and create pam-plugin-cracklib
**need /usr/share/cracklib/pw_dict.pwd file, please run command on host machine:
 cp /usr/share/cracklib/cracklib-small /tmp
 gzip /tmp/cracklib-small
 create-cracklib-dict /tmp/cracklib-small.gz
== Notes ==
=== Packages dropped ===
At the beginning we got a list of packages that use pam. After more work, some of them are dropped.
* consolekit provides a pam plugin module pam_ck_connector.so and not the package that use pam. Drop it.
* gnome-keyring can't call configuration file like "/etc/pam.d/gnome-keyring" because it is called by other program like "gnome-screensave" and "gdm". If we want test "pam_gnome_keyring.so", we need write .bb files to cross-compile gnome-screensave or gdm. So drop it.
* util-linux: 3 programs chfn chsh and login in util-linux will use libpam. Right now these programs are provided by package shadow. In util-linux.inc, EXTRA_OECONF has option "--disable-login-utils " which will disable to build them. Drop it.
* mc: mc has remove package mcserv and dropped dependency on PAM already, but didn't remove checking security/pam_misc.h. Drop it. Official change log
* libcap: if pam exists, libcap will create a pam plugin pam_cap.so to add a new front end for the authentication function. Because it is not a application, remove it from list.
* libuser: pam is libuser's build dependency, so remove it too.
* The busybox login has a option to use pam, but we use tinylogin's login right now (tinylogin also provides the su command)
* If you want to use pam_limits in /etc/pam.d/login, you have to add VIRTUAL-RUNTIME_login_manager = "busybox" to your distro config in order to replace tinylogin with busybox, as tinylogin does not provide PAM capabilites; also make sure that "login" and "PAM" are enabled in your busybox config
* gettext only has a example "hello-c++-kde" use pam under source code directory, and it doen't be compiled and only copied to destination. So omit gettext.
* sysvinit has a patch contrib/notify-pam-dead.patch for /sbin/init to use pam, but the whole contrib directory didn't take part in compilation. Drop it.
* xserver: based on following 2 reason drop it.
** the code use pam is old. Add xserver to original list to be pam-enabled by "bzgrep" tar balls. But in xserver the code to use pam only in os/utils.c function CheckUserAuthorization. No configure mechanism is provided to define macro USE_PAM to make the pam codes enabled. According to the comments, pam authentication only done for setuid servers (uid != euid). Our Xorg is not a setuid server, so we don't need it .
** Xorg in Fedora doesn't support pam. Once I check the xorg-x11-server.spec, and it installs a pam related configure file, so I thought it is pam enabled. But I check the executable file /usr/bin/Xorg , that /usr/bin/Xorg even doesn't link to libpam or libpam_misc. The config file "xserver" is also from Fedora 15, because it is not supported by Fedora itself we don't have any reason to support the configure file in oe.
=== Common configure files ===
When import pam related configure file for each package from Fedora, it may contains "include system-auth". System-auth is the Fedora common configure file and it is autogenerated by command authconfig. It contain all 4 types(auth, account, session, password) rules. But in Yocto these common rules are seperated according pam type, and they are common-auth, common-account, common-session and common-password.
So if configure files from Fedora contains system-auth, we use the seperated common configure files instead.