1API
2
3 bool pam_auth(string $username, string $password
4 [, string &$error [, $checkacctmgmt = true [, string $servicename ] ] ])
5 bool pam_chpass(string $username, string $oldpassword, string $newpassword
6 [, string &$error [, string $servicename ] ])
7
8 The parameters are
9
10 username - Username to check
11 password - User supplied password
12 error - Output parameter to put any error messages in
13 checkacctmgmt - Call pam_acct_mgmt() to check account expiration and access hours (requires root access!)
14 servicename - PAM service name to use (provided pam.force_servicename is not TRUE)
15 oldpassword - Current password on account
16 newpassword - Password to change to
17
18INSTALLATION
19
20 For pam_auth and pam_chpass to work, module must know about the PAM service to use.
21
22 By default, the PAM service is set to "php". It can be changed by adding the following
23 to your php.ini:
24
25 pam.servicename = "your-pam-service";
26
27 Service name can also be, optionally, passed as a parameter to pam_auth OR pam_chpass.
28
29 You can inform the module to ignore the service name passed as a parameter and use
30 pam.servicename only, by adding the following to your php.ini:
31
32 pam.force_servicename = 1;
33
34 Next, you'll need to create a pam service file for php. If you are on linux,
35 you'll need to create the file /etc/pam.d/php. You can copy another one to work
36 off of (/etc/pam.d/login is a good choice).
37
38 Some examples that should work:
39
40 on linux:
41
42# /etc/pam.d/php
43#
44# note: both an auth and account entry are required
45
46auth sufficient /lib/security/pam_pwdb.so shadow nodelay
47account sufficient /lib/security/pam_pwdb.so
48
49 on solaris:
50
51# add to /etc/pam.conf
52
53php auth requisite /usr/lib/security/pam_authtok_get.so.1
54php auth required /usr/lib/security/pam_unix_auth.so.1
55php account required /usr/lib/security/pam_unix_account.so.1
56
57 These would authenticate out of the unix password and shadow file. However
58 please checking other /etc/pam.d/ entries, as the libraries these examples
59 point to may not be correct.
60
61
62FAQ
63
64 * What is PAM?
65
66 PAM stands for Pluggable Authentication Module. It is a system that abstracts
67 user authentication to allow arbitrary modules to handle the real work. In this
68 way, pam enabled services can use a variety of complex authentication schemes
69 without modifying the applications. For more Information, and available
70 modules, see http://www.kernel.org/pub/linux/libs/pam/.
71
72
73 * Why would I want to use PAM from PHP?
74
75 PAM gives you very flexible control over authentication. As an example, there
76 are PAM modules that will authenticate against a local shadow or password file,
77 a Windows NT domain, an SQL database, LDAP, Kerberos, Radius, and more. In
78 addition, pam modules can give you the ability to have restrictions on the
79 authentication, such as the pam_tally module which limits the number of login
80 attempts, and the pam_listfile which let's you restrict access to a list of
81 users. Please note, using pam does not mean you can securely authenticate
82 users, it simply gives you the ability to do so with proper configuration and
83 planning.
84
85
86 * How can I get pam?
87
88 If you are running linux or solaris, you already have it! Linux and Solaris
89 both natively use pam for all authentication, so you're are all set. If you are
90 on other systems, well, you're on your own. I have no idea what PAM has been
91 ported too...
92
93
94 * I'm getting an Authentication Failure error, why?
95
96 Try setting the $checkacctmgmt parameter to false to skip the pam_acct_mgmt()
97 call, note that this only checks the password and skips performing account
98 validation such as account expiration and access. Otherwise see below.
99
100 The most likely reason for this is that you are trying to authenticate via a
101 local shadow file and you do not have permission to do so. The PAM modules
102 handling shadow authentication (used on Linux and Solaris) require that the
103 application have permission to read the shadow file (makes sense, eh?). If you
104 are running php as a cgi or as a webserver module, it is executed as your
105 webservers user and group.
106
107 By default, most Linux and Solaris systems are configured to only allow the root
108 user to read the shadow file. The recommended
109 way around this is to change permissions on the shadow file so that it is group
110 readable, and chgrp the file to the a group that the webserver is in. Before
111 doing this, you should give it some serious thought as allowing your webserver
112 to read the shadow file gives hackers another way to crack away at your system.
113
114 If you decide to enable this, I stronly suggest usage of the pam_tally module
115 to limit failed logins to a reasonable number of attempts, and one of the other
116 modules which will allow you to block root and other system users.
117
118
119 * The pam_auth function doesn't return anything, whattup?
120
121 Did you remember to create an entry in the pam configuration for the php
122 service?
123
124
125 * Logs indicate pam authenticated the user, but the function doesn't return
126 true, what gives?
127
128 Make sure your pam configuration has an entry for both auth and account, if you
129 do not have both, it will not work.
130