1 .\" Title: pam_namespace
2 .\" Author: [see the "AUTHORS" section]
3 .\" Generator: DocBook XSL Stylesheets v1.74.0 <http://docbook.sf.net/>
5 .\" Manual: Linux-PAM Manual
6 .\" Source: Linux-PAM Manual
9 .TH "PAM_NAMESPACE" "8" "08/17/2012" "Linux-PAM Manual" "Linux-PAM Manual"
10 .\" -----------------------------------------------------------------
11 .\" * (re)Define some macros
12 .\" -----------------------------------------------------------------
13 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
14 .\" toupper - uppercase a string (locale-aware)
15 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
17 .tr aAbBcCdDeEfFgGhHiIjJkKlLmMnNoOpPqQrRsStTuUvVwWxXyYzZ
19 .tr aabbccddeeffgghhiijjkkllmmnnooppqqrrssttuuvvwwxxyyzz
21 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
22 .\" SH-xref - format a cross-reference to an SH section
23 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
32 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
33 .\" SH - level-one heading that works better for non-TTY output
34 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
36 .\" put an extra blank line of space above the head in non-TTY output
43 .nr an-prevailing-indent \\n[IN]
47 .HTML-TAG ".NH \\n[an-level]"
49 .nr an-no-space-flag 1
51 \." make the size of the head bigger
56 .\" if n (TTY output), use uppercase
61 .\" if not n (not TTY), use normal case (not uppercase)
65 .\" if not n (not TTY), put a border/line under subheading
70 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
71 .\" SS - level-two heading that works better for non-TTY output
72 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
77 .nr an-prevailing-indent \\n[IN]
82 .nr an-no-space-flag 1
85 \." make the size of the head bigger
91 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
92 .\" BB/BE - put background/screen (filled box) around block of text
93 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
106 .if "\\$2"adjust-for-leading-newline" \{\
114 .nr BW \\n(.lu-\\n(.i
117 .ie "\\$2"adjust-for-leading-newline" \{\
118 \M[\\$1]\h'1n'\v'+.5v'\D'P \\n(BWu 0 0 \\n(BHu -\\n(BWu 0 0 -\\n(BHu'\M[]
121 \M[\\$1]\h'1n'\v'-.5v'\D'P \\n(BWu 0 0 \\n(BHu -\\n(BWu 0 0 -\\n(BHu'\M[]
132 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
133 .\" BM/EM - put colored marker in margin next to block of text
134 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
151 \M[\\$1]\D'P -.75n 0 0 \\n(BHu -(\\n[.i]u - \\n(INu - .75n) 0 0 -\\n(BHu'\M[]
159 .\" -----------------------------------------------------------------
160 .\" * set default formatting
161 .\" -----------------------------------------------------------------
162 .\" disable hyphenation
164 .\" disable justification (adjust text to left margin only)
166 .\" -----------------------------------------------------------------
167 .\" * MAIN CONTENT STARTS HERE *
168 .\" -----------------------------------------------------------------
170 pam_namespace \- PAM module for configuring namespace for a session
173 .HP \w'\fBpam_namespace\&.so\fR\ 'u
174 \fBpam_namespace\&.so\fR [debug] [unmnt_remnt] [unmnt_only] [require_selinux] [gen_hash] [ignore_config_error] [ignore_instance_parent_mode] [unmount_on_close] [use_current_context] [use_default_context] [mount_private]
178 The pam_namespace PAM module sets up a private namespace for a session with polyinstantiated directories\&. A polyinstantiated directory provides a different instance of itself based on user name, or when using SELinux, user name, security context or both\&. If an executable script
179 \FC/etc/security/namespace\&.init\F[]
180 exists, it is used to initialize the instance directory after it is set up and mounted on the polyinstantiated directory\&. The script receives the polyinstantiated directory path, the instance directory path, flag whether the instance directory was newly created (0 for no, 1 for yes), and the user name as its arguments\&.
182 The pam_namespace module disassociates the session namespace from the parent namespace\&. Any mounts/unmounts performed in the parent namespace, such as mounting of devices, are not reflected in the session namespace\&. To propagate selected mount/unmount events from the parent namespace into the disassociated session namespace, an administrator may use the special shared\-subtree feature\&. For additional information on shared\-subtree feature, please refer to the mount(8) man page and the shared\-subtree description at http://lwn\&.net/Articles/159077 and http://lwn\&.net/Articles/159092\&.
187 A lot of debug information is logged using syslog
192 For programs such as su and newrole, the login session has already setup a polyinstantiated namespace\&. For these programs, polyinstantiation is performed based on new user id or security context, however the command first needs to undo the polyinstantiation performed by login\&. This argument instructs the command to first undo previous polyinstantiation before proceeding with new polyinstantiation based on new id/context
197 For trusted programs that want to undo any existing bind mounts and process instance directories on their own, this argument allows them to unmount currently mounted instance directories
200 \fBrequire_selinux\fR
202 If selinux is not enabled, return failure
207 Instead of using the security context string for the instance name, generate and use its md5 hash\&.
210 \fBignore_config_error\fR
212 If a line in the configuration file corresponding to a polyinstantiated directory contains format error, skip that line process the next line\&. Without this option, pam will return an error to the calling program resulting in termination of the session\&.
215 \fBignore_instance_parent_mode\fR
217 Instance parent directories by default are expected to have the restrictive mode of 000\&. Using this option, an administrator can choose to ignore the mode of the instance parent\&. This option should be used with caution as it will reduce security and isolation goals of the polyinstantiation mechanism\&.
220 \fBunmount_on_close\fR
222 Explicitly unmount the polyinstantiated directories instead of relying on automatic namespace destruction after the last process in a namespace exits\&. This option should be used only in case it is ensured by other means that there cannot be any processes running in the private namespace left after the session close\&. It is also useful only in case there are multiple pam session calls in sequence from the same process\&.
225 \fBuse_current_context\fR
227 Useful for services which do not change the SELinux context with setexeccon call\&. The module will use the current SELinux context of the calling process for the level and context polyinstantiation\&.
230 \fBuse_default_context\fR
232 Useful for services which do not use pam_selinux for changing the SELinux context with setexeccon call\&. The module will use the default SELinux context of the user for the level and context polyinstantiation\&.
237 This option can be used on systems where the / mount point or its submounts are made shared (for example with a
238 \fBmount \-\-make\-rshared /\fR
239 command)\&. The module will mark the whole directory tree so any mount and unmount operations in the polyinstantiation namespace are private\&. Normally the pam_namespace will try to detect the shared / mount point and make the polyinstantiated directories private automatically\&. This option has to be used just when only a subtree is shared and / is not\&.
241 Note that mounts and unmounts done in the private namespace will not affect the parent namespace if this option is used or when the shared / mount point is autodetected\&.
243 .SH "MODULE TYPES PROVIDED"
247 module type is provided\&. The module must not be called from multithreaded processes\&.
252 Namespace setup was successful\&.
257 Unexpected system error occurred while setting up namespace\&.
262 Unexpected namespace configuration error occurred\&.
266 \FC/etc/security/namespace\&.conf\F[]
268 Main configuration file
271 \FC/etc/security/namespace\&.d\F[]
273 Directory for additional configuration files
276 \FC/etc/security/namespace\&.init\F[]
278 Init script for instance directories
282 For the <service>s you need polyinstantiation (login for example) put the following line in /etc/pam\&.d/<service> as the last line for session group:
284 session required pam_namespace\&.so [arguments]
286 To use polyinstantiation with graphical display manager gdm, insert the following line, before exit 0, in /etc/gdm/PostSession/Default:
288 /usr/sbin/gdm\-safe\-restart
290 This allows gdm to restart after each session and appropriately adjust namespaces of display manager and the X server\&. If polyinstantiation of /tmp is desired along with the graphical environment, then additional configuration changes are needed to address the interaction of X server and font server namespaces with their use of /tmp to create communication sockets\&. Please use the initialization script
291 \FC/etc/security/namespace\&.init\F[]
292 to ensure that the X server and its clients can appropriately access the communication socket X0\&. Please refer to the sample instructions provided in the comment section of the instance initialization script
293 \FC/etc/security/namespace\&.init\F[]\&. In addition, perform the following changes to use graphical environment with polyinstantiation of /tmp:
306 .BB lightgray adjust-for-leading-newline
309 1\&. Disable the use of font server by commenting out "FontPath"
310 line in /etc/X11/xorg\&.conf\&. If you do want to use the font server
311 then you will have to augment the instance initialization
312 script to appropriately provide /tmp/\&.font\-unix from the
313 polyinstantiated /tmp\&.
314 2\&. Ensure that the gdm service is setup to use pam_namespace,
315 as described above, by modifying /etc/pam\&.d/gdm\&.
316 3\&. Ensure that the display manager is configured to restart X server
317 with each new session\&. This default setup can be verified by
318 making sure that /usr/share/gdm/defaults\&.conf contains
319 "AlwaysRestartServer=true", and it is not overridden by
320 /etc/gdm/custom\&.conf\&.
322 .EB lightgray adjust-for-leading-newline
336 \fBnamespace.conf\fR(5),
342 The namespace setup scheme was designed by Stephen Smalley, Janak Desai and Chad Sellers\&. The pam_namespace PAM module was developed by Janak Desai <janak@us\&.ibm\&.com>, Chad Sellers <csellers@tresys\&.com> and Steve Grubb <sgrubb@redhat\&.com>\&. Additional improvements by Xavier Toth <txtoth@gmail\&.com> and Tomas Mraz <tmraz@redhat\&.com>\&.