diff options
Diffstat (limited to 'modules/pam_namespace')
| -rw-r--r-- | modules/pam_namespace/README | 281 | ||||
| -rw-r--r-- | modules/pam_namespace/namespace.conf.5 | 129 | ||||
| -rw-r--r-- | modules/pam_namespace/pam_namespace.8 | 59 |
3 files changed, 270 insertions, 199 deletions
diff --git a/modules/pam_namespace/README b/modules/pam_namespace/README index c47ba232..cf5814e3 100644 --- a/modules/pam_namespace/README +++ b/modules/pam_namespace/README @@ -2,128 +2,167 @@ pam_namespace — PAM module for configuring namespace for a session ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ +DESCRIPTION -pam_namespace module: -Setup a private namespace with polyinstantiated directories. - -THEORY OF OPERATION: -The pam namespace module consults /etc/security/namespace.conf -configuration file and sets up a private namespace with polyinstantiated -directories for a session managed by PAM. A skeleton namespace.conf -installed by default provides example for polyinstantiating /tmp, /var/tmp -and users' home directory. - -If an executable script /etc/security/namespace.init exists, it -is used to initialize the namespace every time a new instance directory -is setup. The script receives the polyinstantiated directory path -and the instance directory path as its arguments. - -Each line in namespace.conf describes a limit for a user in the form: - -<polydir> <instance_prefix> <method> <list_of_uids> - -Where: -<polydir> - is the absolute pathname of the directory to polyinstantiate - Special entry $HOME is supported to designate user's home directory. - This field cannot be blank. - -<instance_prefix> - is the string prefix used to build the pathname for the - instantiation of <polydir>. The directory security context, or - optionally its md5sum string (32 hex characters), is appended to - the prefix to generate the final instance directory path. - This directory is created if it did not exist already, and is then - bind mounted on the <polydir> to provide an instance of <polydir> - based on the <method> column. The special string $HOME is replaced with - the user's home directory, and $USER with the username. - This field cannot be blank. - -<method> - is the method used for polyinstantiation. It can take 3 different - values; "user" for polyinstantiation based on user name, "context" - for polyinstantiation based on process security context, and "both" - for polyinstantiation based on both user name and security context. - Methods "context" and "both" are only available with SELinux. This - field cannot be blank. - -<list_of_uids> - is a comma separated list of user names for whom the - polyinstantiation is not performed. If left blank, polyinstantiation - will be performed for all users. - -EXAMPLE /etc/security/namespace.conf configuration file: -======================================================= -# Following three lines will polyinstantiate /tmp, /var/tmp and user's home -# directories. /tmp and /var/tmp will be polyinstantiated based on both -# security context as well as user name, whereas home directory will -# be polyinstantiated based on security context only. Polyinstantiation -# will not be performed for user root and adm for directories /tmp and -# /var/tmp, whereas home directories will be polyinstantiated for all -# users. The user name and/or context is appended to the instance prefix. -# -# Note that instance directories do not have to reside inside the -# polyinstantiated directory. In the examples below, instances of /tmp -# will be created in /tmp-inst directory, where as instances of /var/tmp -# and users home directories will reside within the directories that -# are being polyinstantiated. -# -# Instance parent directories must exist for the polyinstantiation -# mechanism to work. By default, they should be created with the mode -# of 000. pam_namespace module will enforce this mode unless it -# is explicitly called with an argument to ignore the mode of the -# instance parent. System administrators should use this argument with -# caution, as it will reduce security and isolation achieved by -# polyinstantiation. -# -/tmp /tmp-inst/ both root,adm -/var/tmp /var/tmp/tmp-inst/ both root,adm -$HOME $HOME/$USER.inst/inst- context - -ARGUMENTS RECOGNIZED: - debug - Verbose logging by syslog - - unmnt_remnt - 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. - - unmnt_only - 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. - - require_selinux - If selinux is not enabled, return failure. - - gen_hash - Instead of using the security context string for the instance - name, generate and use its md5 hash. - - ignore_config_error - 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. - - ignore_instance_parent_mode - 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. - -MODULE SERVICES PROVIDED: - session open_session and close_session - -USAGE: - 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: - - session required pam_namespace.so [arguments] - - This module also depends on pam_selinux.so setting the context. +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 /etc/security/namespace.init +exists, it is used to initialize the namespace every time a new instance +directory is setup. The script receives the polyinstantiated directory path and +the instance directory path as its arguments. +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. +OPTIONS + +debug + + A lot of debug information is logged using syslog + +unmnt_remnt + + 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 + +unmnt_only + + 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 + +require_selinux + + If selinux is not enabled, return failure + +gen_hash + + Instead of using the security context string for the instance name, + generate and use its md5 hash. + +ignore_config_error + + 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. + +ignore_instance_parent_mode + + 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. + +no_unmount_on_close + + For certain trusted programs such as newrole, open session is called from a + child process while the parent perfoms close session and pam end functions. + For these commands use this option to instruct pam_close_session to not + unmount the bind mounted polyinstantiated directory in the parent. + +DESCRIPTION + +This module allows setup of private namespaces with polyinstantiated +directories. Directories can be polyinstantiated based on user name or, in the +case of SELinux, user name, sensitivity level or complete security context. If +an executable script /etc/security/namespace.init exists, it is used to +initialize the namespace every time a new instance directory is setup. The +script receives the polyinstantiated directory path and the instance directory +path as its arguments. + +The /etc/security/namespace.conf file specifies which directories are +polyinstantiated, how they are polyinstantiated, how instance directories would +be named, and any users for whom polyinstantiation would not be performed. + +When someone logs in, the file namespace.conf is scanned where each non comment +line represents one polyinstantiated directory with space separated fields as +follows: + +polydir instance_prefix method list_of_uids + +The first field, polydir, is the absolute pathname of the directory to +polyinstantiate. Special entry $HOME is supported to designate user's home +directory. This field cannot be blank. + +The second field, instance_prefix is the string prefix used to build the +pathname for the instantiation of <polydir>. Depending on the polyinstantiation +method it is then appended with "instance differentiation string" to generate +the final instance directory path. This directory is created if it did not +exist already, and is then bind mounted on the <polydir> to provide an instance +of <polydir> based on the <method> column. The special string $HOME is replaced +with the user's home directory, and $USER with the username. This field cannot +be blank. The directory where polyinstantiated instances are to be created, +must exist and must have, by default, the mode of 000. The requirement that the +instance parent be of mode 000 can be overridden with the command line option +ignore_instance_parent_mode + +The third field, method, is the method used for polyinstantiation. It can take +3 different values; "user" for polyinstantiation based on user name, "level" +for polyinstantiation based on process MLS level and user name, and "context" +for polyinstantiation based on process security context and user name Methods +"context" and "level" are only available with SELinux. This field cannot be +blank. + +The fourth field, list_of_uids, is a comma separated list of user names for +whom the polyinstantiation is not performed. If left blank, polyinstantiation +will be performed for all users. + +In case of context or level polyinstantiation the SELinux context which is used +for polyinstantiation is the context used for executing a new process as +obtained by getexeccon. This context must be set by the calling application or +pam_selinux.so module. If this context is not set the polyinstatiation will be +based just on user name. + +The "instance differentiation string" is <user name> for "user" method and +<user name>_<raw directory context> for "context" and "level" methods. If the +whole string is too long the end of it is replaced with md5sum of itself. Also +when command line option gen_hash is used the whole string is replaced with +md5sum of itself. + +EXAMPLES + +These are some example lines which might be specified in /etc/security/ +namespace.conf. + + + # The following three lines will polyinstantiate /tmp, + # /var/tmp and user's home directories. /tmp and /var/tmp + # will be polyinstantiated based on the security level + # as well as user name, whereas home directory will be + # polyinstantiated based on the full security context and user name. + # Polyinstantiation will not be performed for user root + # and adm for directories /tmp and /var/tmp, whereas home + # directories will be polyinstantiated for all users. + # + # Note that instance directories do not have to reside inside + # the polyinstantiated directory. In the examples below, + # instances of /tmp will be created in /tmp-inst directory, + # where as instances of /var/tmp and users home directories + # will reside within the directories that are being + # polyinstantiated. + # + /tmp /tmp-inst/ level root,adm + /var/tmp /var/tmp/tmp-inst/ level root,adm + $HOME $HOME/$USER.inst/inst- context + + +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: + +session required pam_namespace.so [arguments] + +This module also depends on pam_selinux.so setting the context. diff --git a/modules/pam_namespace/namespace.conf.5 b/modules/pam_namespace/namespace.conf.5 index ff325a21..0a4d98e4 100644 --- a/modules/pam_namespace/namespace.conf.5 +++ b/modules/pam_namespace/namespace.conf.5 @@ -1,96 +1,101 @@ -.\"Generated by db2man.xsl. Don't modify this, modify the source. -.de Sh \" Subsection -.br -.if t .Sp -.ne 5 -.PP -\fB\\$1\fR -.PP -.. -.de Sp \" Vertical space (when we can't use .PP) -.if t .sp .5v -.if n .sp -.. -.de Ip \" List item -.br -.ie \\n(.$>=3 .ne \\$3 -.el .ne 3 -.IP "\\$1" \\$2 -.. -.TH "NAMESPACE.CONF" 5 "" "" "" -.SH NAME +.\" Title: namespace.conf +.\" Author: +.\" Generator: DocBook XSL Stylesheets v1.71.1 <http://docbook.sf.net/> +.\" Date: 06/20/2007 +.\" Manual: Linux\-PAM Manual +.\" Source: Linux\-PAM Manual +.\" +.TH "NAMESPACE.CONF" "5" "06/20/2007" "Linux\-PAM Manual" "Linux\-PAM Manual" +.\" disable hyphenation +.nh +.\" disable justification (adjust text to left margin only) +.ad l +.SH "NAME" namespace.conf \- the namespace configuration file .SH "DESCRIPTION" - .PP -This module allows setup of private namespaces with polyinstantiated directories\&. Directories can be polyinstantiated based on user name or, in the case of SELinux, user name, security context or both\&. If an executable script \fI/etc/security/namespace\&.init\fR exists, it is used to initialize the namespace every time a new instance directory is setup\&. The script receives the polyinstantiated directory path and the instance directory path as its arguments\&. - +This module allows setup of private namespaces with polyinstantiated directories. Directories can be polyinstantiated based on user name or, in the case of SELinux, user name, sensitivity level or complete security context. If an executable script +\fI/etc/security/namespace.init\fR +exists, it is used to initialize the namespace every time a new instance directory is setup. The script receives the polyinstantiated directory path and the instance directory path as its arguments. .PP -The \fI/etc/security/namespace\&.conf\fR file specifies which directories are polyinstantiated, how they are polyinstantiated, how instance directories would be named, and any users for whom polyinstantiation would not be performed\&. - +The +\fI/etc/security/namespace.conf\fR +file specifies which directories are polyinstantiated, how they are polyinstantiated, how instance directories would be named, and any users for whom polyinstantiation would not be performed. .PP -When someone logs in, the file \fInamespace\&.conf\fR is scanned where each non comment line represents one polyinstantiated directory with space separated fields as follows: - +When someone logs in, the file +\fInamespace.conf\fR +is scanned where each non comment line represents one polyinstantiated directory with space separated fields as follows: .PP - \fIpolydir\fR \fI instance_prefix\fR \fI method\fR \fI list_of_uids\fR +\fIpolydir\fR +\fI instance_prefix\fR +\fI method\fR +\fI list_of_uids\fR .PP -The first field, \fIpolydir\fR, is the absolute pathname of the directory to polyinstantiate\&. Special entry $HOME is supported to designate user's home directory\&. This field cannot be blank\&. - +The first field, +\fIpolydir\fR, is the absolute pathname of the directory to polyinstantiate. Special entry $HOME is supported to designate user's home directory. This field cannot be blank. .PP -The second field, \fIinstance_prefix\fR is the string prefix used to build the pathname for the instantiation of <polydir>\&. The directory security context, or optionally its md5sum string (32 hex characters), is appended to the prefix to generate the final instance directory path\&. This directory is created if it did not exist already, and is then bind mounted on the <polydir> to provide an instance of <polydir> based on the <method> column\&. The special string $HOME is replaced with the user's home directory, and $USER with the username\&. This field cannot be blank\&. The directory where polyinstantiated instances are to be created, must exist and must have, by default, the mode of 000\&. The requirement that the instance parent be of mode 000 can be overridden with the command line option <ignore_instance_parent_mode> - +The second field, +\fIinstance_prefix\fR +is the string prefix used to build the pathname for the instantiation of <polydir>. Depending on the polyinstantiation +\fImethod\fR +it is then appended with "instance differentiation string" to generate the final instance directory path. This directory is created if it did not exist already, and is then bind mounted on the <polydir> to provide an instance of <polydir> based on the <method> column. The special string $HOME is replaced with the user's home directory, and $USER with the username. This field cannot be blank. The directory where polyinstantiated instances are to be created, must exist and must have, by default, the mode of 000. The requirement that the instance parent be of mode 000 can be overridden with the command line option +\fIignore_instance_parent_mode\fR .PP -The third field, \fImethod\fR, is the method used for polyinstantiation\&. It can take 3 different values; "user" for polyinstantiation based on user name, "context" for polyinstantiation based on process security context, and "both" for polyinstantiation based on both user name and security context\&. Methods "context" and "both" are only available with SELinux\&. This field cannot be blank\&. - +The third field, +\fImethod\fR, is the method used for polyinstantiation. It can take 3 different values; "user" for polyinstantiation based on user name, "level" for polyinstantiation based on process MLS level and user name, and "context" for polyinstantiation based on process security context and user name Methods "context" and "level" are only available with SELinux. This field cannot be blank. .PP -The fourth field, \fIlist_of_uids\fR, is a comma separated list of user names for whom the polyinstantiation is not performed\&. If left blank, polyinstantiation will be performed for all users\&. - +The fourth field, +\fIlist_of_uids\fR, is a comma separated list of user names for whom the polyinstantiation is not performed. If left blank, polyinstantiation will be performed for all users. +.PP +In case of context or level polyinstantiation the SELinux context which is used for polyinstantiation is the context used for executing a new process as obtained by getexeccon. This context must be set by the calling application or +\fIpam_selinux.so\fR +module. If this context is not set the polyinstatiation will be based just on user name. +.PP +The "instance differentiation string" is <user name> for "user" method and <user name>_<raw directory context> for "context" and "level" methods. If the whole string is too long the end of it is replaced with md5sum of itself. Also when command line option +\fIgen_hash\fR +is used the whole string is replaced with md5sum of itself. .SH "EXAMPLES" - .PP -These are some example lines which might be specified in \fI/etc/security/namespace\&.conf\fR\&. - +These are some example lines which might be specified in +\fI/etc/security/namespace.conf\fR. +.sp +.RS 4 .nf - # The following three lines will polyinstantiate /tmp, - # /var/tmp and user's home directories\&. /tmp and /var/tmp - # will be polyinstantiated based on both security context + # /var/tmp and user's home directories. /tmp and /var/tmp + # will be polyinstantiated based on the security level # as well as user name, whereas home directory will be - # polyinstantiated based on security context only\&. + # polyinstantiated based on the full security context and user name. # Polyinstantiation will not be performed for user root # and adm for directories /tmp and /var/tmp, whereas home - # directories will be polyinstantiated for all users\&. + # directories will be polyinstantiated for all users. # # Note that instance directories do not have to reside inside - # the polyinstantiated directory\&. In the examples below, + # the polyinstantiated directory. In the examples below, # instances of /tmp will be created in /tmp\-inst directory, # where as instances of /var/tmp and users home directories # will reside within the directories that are being - # polyinstantiated\&. + # polyinstantiated. # - /tmp /tmp\-inst/ both root,adm - /var/tmp /var/tmp/tmp\-inst/ both root,adm - $HOME $HOME/$USER\&.inst/inst\- context + /tmp /tmp\-inst/ level root,adm + /var/tmp /var/tmp/tmp\-inst/ level root,adm + $HOME $HOME/$USER.inst/inst\- context .fi - +.RE .PP -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: - +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: .PP -session required pam_namespace\&.so [arguments] - +session required pam_namespace.so [arguments] .PP -This module also depends on pam_selinux\&.so setting the context\&. - +This module also depends on pam_selinux.so setting the context. .SH "SEE ALSO" - .PP - \fBpam_namespace\fR(8), \fBpam\&.d\fR(5), \fBpam\fR(8) +\fBpam_namespace\fR(8), +\fBpam.d\fR(5), +\fBpam\fR(8) .SH "AUTHORS" - .PP -The namespace\&.conf manual page was written by Janak Desai <janak@us\&.ibm\&.com>\&. - +The namespace.conf manual page was written by Janak Desai <janak@us.ibm.com>. diff --git a/modules/pam_namespace/pam_namespace.8 b/modules/pam_namespace/pam_namespace.8 index 126cfc88..8d136c99 100644 --- a/modules/pam_namespace/pam_namespace.8 +++ b/modules/pam_namespace/pam_namespace.8 @@ -1,11 +1,11 @@ .\" Title: pam_namespace .\" Author: -.\" Generator: DocBook XSL Stylesheets v1.70.1 <http://docbook.sf.net/> -.\" Date: 06/27/2006 +.\" Generator: DocBook XSL Stylesheets v1.71.1 <http://docbook.sf.net/> +.\" Date: 06/20/2007 .\" Manual: Linux\-PAM Manual .\" Source: Linux\-PAM Manual .\" -.TH "PAM_NAMESPACE" "8" "06/27/2006" "Linux\-PAM Manual" "Linux\-PAM Manual" +.TH "PAM_NAMESPACE" "8" "06/20/2007" "Linux\-PAM Manual" "Linux\-PAM Manual" .\" disable hyphenation .nh .\" disable justification (adjust text to left margin only) @@ -14,7 +14,7 @@ pam_namespace \- PAM module for configuring namespace for a session .SH "SYNOPSIS" .HP 17 -\fBpam_namespace.so\fR [debug] [unmnt_remnt] [unmnt_only] [require_selinux] [gen_hash] [ignore_config_error] [ignore_instance_parent_mode] +\fBpam_namespace.so\fR [debug] [unmnt_remnt] [unmnt_only] [require_selinux] [gen_hash] [ignore_config_error] [ignore_instance_parent_mode] [no_unmount_on_close] .SH "DESCRIPTION" .PP 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 @@ -23,46 +23,73 @@ exists, it is used to initialize the namespace every time a new instance directo .PP 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. .SH "OPTIONS" -.TP 3n +.PP \fBdebug\fR +.RS 4 A lot of debug information is logged using syslog -.TP 3n +.RE +.PP \fBunmnt_remnt\fR +.RS 4 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 -.TP 3n +.RE +.PP \fBunmnt_only\fR +.RS 4 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 -.TP 3n +.RE +.PP \fBrequire_selinux\fR +.RS 4 If selinux is not enabled, return failure -.TP 3n +.RE +.PP \fBgen_hash\fR +.RS 4 Instead of using the security context string for the instance name, generate and use its md5 hash. -.TP 3n +.RE +.PP \fBignore_config_error\fR +.RS 4 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. -.TP 3n +.RE +.PP \fBignore_instance_parent_mode\fR +.RS 4 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. +.RE +.PP +\fBno_unmount_on_close\fR +.RS 4 +For certain trusted programs such as newrole, open session is called from a child process while the parent perfoms close session and pam end functions. For these commands use this option to instruct pam_close_session to not unmount the bind mounted polyinstantiated directory in the parent. +.RE .SH "MODULE SERVICES PROVIDED" .PP The \fBsession\fR service is supported. .SH "RETURN VALUES" -.TP 3n +.PP PAM_SUCCESS +.RS 4 Namespace setup was successful. -.TP 3n +.RE +.PP PAM_SERVICE_ERR +.RS 4 Unexpected system error occurred while setting up namespace. -.TP 3n +.RE +.PP PAM_SESSION_ERR +.RS 4 Unexpected namespace configuration error occurred. +.RE .SH "FILES" -.TP 3n +.PP \fI/etc/security/namespace.conf\fR +.RS 4 Configuration file +.RE .SH "EXAMPLES" .PP 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: @@ -80,7 +107,7 @@ to ensure that the X server and its clients can appropriately access the communi .PP .sp -.RS 3n +.RS 4 .nf 1. Disable the use of font server by commenting out "FontPath" line in /etc/X11/xorg.conf. If you do want to use the font server |