1.\" Copyright (c) 2001 Mark R V Murray 2.\" All rights reserved. 3.\" Copyright (c) 2001 Networks Associates Technology, Inc. 4.\" All rights reserved. 5.\" 6.\" This software was developed for the FreeBSD Project by ThinkSec AS and 7.\" NAI Labs, the Security Research Division of Network Associates, Inc. 8.\" under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the 9.\" DARPA CHATS research program. 10.\" 11.\" Redistribution and use in source and binary forms, with or without 12.\" modification, are permitted provided that the following conditions 13.\" are met: 14.\" 1. Redistributions of source code must retain the above copyright 15.\" notice, this list of conditions and the following disclaimer. 16.\" 2. Redistributions in binary form must reproduce the above copyright 17.\" notice, this list of conditions and the following disclaimer in the 18.\" documentation and/or other materials provided with the distribution. 19.\" 3. The name of the author may not be used to endorse or promote 20.\" products derived from this software without specific prior written 21.\" permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.Dd April 3, 2020 36.Dt PAM_UNIX 8 37.Os 38.Sh NAME 39.Nm pam_unix 40.Nd UNIX PAM module 41.Sh SYNOPSIS 42.Op Ar service-name 43.Ar module-type 44.Ar control-flag 45.Pa pam_unix 46.Op Ar options 47.Sh DESCRIPTION 48The 49.Ux 50authentication service module for PAM, 51.Nm 52provides functionality for three PAM categories: 53authentication, account management, and password management. 54In terms of the 55.Ar module-type 56parameter, they are the 57.Dq Li auth , 58.Dq Li account , 59and 60.Dq Li password 61features. 62It also provides a null function for session management. 63.Ss Ux Ss Authentication Module 64The 65.Ux 66authentication component provides functions to verify the identity of 67a user 68.Pq Fn pam_sm_authenticate , 69which obtains the relevant 70.Xr passwd 5 71entry. 72It prompts the user for a password and verifies that this is correct with 73.Xr crypt 3 . 74.Pp 75The following options may be passed to the authentication module: 76.Bl -tag -width ".Cm use_first_pass" 77.It Cm debug 78.Xr syslog 3 79debugging information at 80.Dv LOG_DEBUG 81level. 82.It Cm use_first_pass 83If the authentication module is not the first in the stack, and a 84previous module obtained the user's password, that password is used to 85authenticate the user. 86If this fails, the authentication module returns failure without 87prompting the user for a password. 88This option has no effect if the authentication module is the first in 89the stack, or if no previous modules obtained the user's password. 90.It Cm try_first_pass 91This option is similar to the 92.Cm use_first_pass 93option, except that if the previously obtained password fails, the 94user is prompted for another password. 95.It Cm auth_as_self 96This option will require the user to authenticate themselves as 97themselves, not as the account they are attempting to access. 98This is primarily for services like 99.Xr su 1 , 100where the user's ability to retype their own password might be deemed 101sufficient. 102.It Cm nullok 103If the password database has no password for the entity being 104authenticated, then this option will forgo password prompting, and 105silently allow authentication to succeed. 106.Pp 107.Sy NOTE: 108If 109.Nm 110is invoked by a process that does not have the privileges required to 111access the password database (in most cases, this means root 112privileges), the 113.Cm nullok 114option may cause 115.Nm 116to allow any user to log in with any password. 117.It Cm emptyok 118If the password database contains the password for the entity being 119authenticated, but the password matches an empty string, 120then this option will forgo password prompting, and 121silently allow authentication to succeed. 122.Pp 123The difference between this and 124.Cm nullok 125is that it avoids prompting for password when the password is set 126to an empty string, as opposed to not being set. 127.It Cm local_pass 128Use only the local password database, even if NIS is in use. 129This will cause an authentication failure if the system is configured 130to only use NIS. 131.It Cm nis_pass 132Use only the NIS password database. 133This will cause an authentication failure if the system is not 134configured to use NIS. 135.El 136.Ss Ux Ss Account Management Module 137The 138.Ux 139account management component provides a function to perform account 140management, 141.Fn pam_sm_acct_mgmt . 142The function verifies that the authenticated user is allowed to log 143into the local user account by checking the following criteria: 144.Bl -dash -offset indent 145.It 146locked status of the account compatible with 147.Xr pw 8 148.Cm lock ; 149.It 150the password expiry date from 151.Xr passwd 5 ; 152.It 153.Xr login.conf 5 154restrictions on the remote host, login time, and tty. 155.El 156.Pp 157The following options may be passed to the management module: 158.Bl -tag -width ".Cm use_first_pass" 159.It Cm debug 160.Xr syslog 3 161debugging information at 162.Dv LOG_DEBUG 163level. 164.El 165.Ss Ux Ss Password Management Module 166The 167.Ux 168password management component provides a function to perform password 169management, 170.Fn pam_sm_chauthtok . 171The function changes 172the user's password. 173.Pp 174The following options may be passed to the password module: 175.Bl -tag -width ".Cm use_first_pass" 176.It Cm debug 177.Xr syslog 3 178debugging information at 179.Dv LOG_DEBUG 180level. 181.It Cm no_warn 182suppress warning messages to the user. 183These messages include reasons why the user's authentication attempt 184was declined. 185.It Cm local_pass 186forces the password module to change a local password in favour of a 187NIS one. 188.It Cm nis_pass 189forces the password module to change a NIS password in favour of a 190local one. 191.El 192.Sh FILES 193.Bl -tag -width ".Pa /etc/master.passwd" -compact 194.It Pa /etc/master.passwd 195default 196.Ux 197password database. 198.El 199.Sh SEE ALSO 200.Xr passwd 1 , 201.Xr getlogin 2 , 202.Xr crypt 3 , 203.Xr getpwent 3 , 204.Xr syslog 3 , 205.Xr nsswitch.conf 5 , 206.Xr passwd 5 , 207.Xr pam 3 , 208.Xr pw 8 , 209.Xr yp 8 210.Sh BUGS 211The 212.Nm 213module ignores the 214.Dv PAM_CHANGE_EXPIRED_AUTHTOK 215flag. 216