I've just introduced mod_privileges to Apache HTTPD trunk.
This is a platform-specific module for Solaris 10 and OpenSolaris, that makes the webserver privileges(5)-aware. This enables the server to be run with enhanced security, and with different settings per virtual host. The feature likely to be of most interest is that it enables different virtual hosts to run under different Unix user and group IDs, using the VHostUser and VHostGroup directives. This is the capability once promised by the "perchild" MPM. It has one major drawback: it is not suitable for a threaded MPM. However, it is ideally suited for use with PHP, which of course also precludes threads. It should also be of interest to anyone hosting other in-process scripting environments such as mod_perl, mod_python or mod_ruby, or application modules. http://svn.apache.org/viewvc/httpd/httpd/trunk/modules/arch/unix/mod_privileges.c http://svn.apache.org/viewvc/httpd/httpd/trunk/docs/manual/mod/mod_privileges.xml -- Nick KewTitle: mod_privileges - Apache HTTP Server
Apache HTTP Server Version 2.3
Apache Module mod_privileges
Available Languages: en
| Description: | Support for Solaris privileges and for running virtual hosts under different user IDs. |
|---|---|
| Status: | Experimental |
| Module Identifier: | privileges_module |
| Compatibility: | Available in Apache 2.3 and up, on Solaris 10 and OpenSolaris platforms |
Summary
This module enables different Virtual Hosts to run with different
Unix™ User and Group IDs, and with different
Solaris Privileges. In particular, it offers a solution to the
problem of privilege separation between different Virtual Hosts, first
promised by the abandoned perchild MPM.
It also offers other security enhancements.
Unlike perchild, mod_privileges
is not itself an MPM. It works within a processing model to
set privileges and User/Group per request in a running process.
It is therefore not compatible with a threaded MPM, and will refuse
to run under one.
mod_privileges raises security issues similar to
those of suexec. But unlike suexec,
it applies not only to CGI programs but to the entire request processing
cycle, including in-process applications and subprocesses.
It is ideally suited to running PHP applications under mod_php,
which is also incompatible with threaded MPMs. It is also well-suited
to other in-process scripting applications such as mod_perl,
mod_python, and mod_ruby, and to
applications implemented in C as apache modules where privilege
separation is an issue.
DTracePrivileges Directive
| Description: | Determines whether the privileges required by dtrace are enabled. |
|---|---|
| Syntax: | DTracePrivileges On|Off |
| Default: | DTracePrivileges Off |
| Context: | server config |
| Status: | Experimental |
| Module: | mod_privileges |
| Compatibility: | Available on Solaris 10 and OpenSolaris with
non-threaded MPMs (prefork or custom MPM). |
This server-wide directive determines whether Apache will run with the privileges required to run dtrace. Note that DTracePrivileges On will not in itself activate DTrace, but DTracePrivileges Off will prevent it working.
VHostCGIMode Directive
| Description: | Determines whether the virtualhost can run subprocesses, and the privileges available to subprocesses. |
|---|---|
| Syntax: | VHostCGIMode On|Off|Secure |
| Default: | VHostCGIMode On |
| Context: | virtual host |
| Status: | Experimental |
| Module: | mod_privileges |
| Compatibility: | Available on Solaris 10 and OpenSolaris with
non-threaded MPMs (prefork or custom MPM). |
Determines whether the virtual host is allowed to run fork and exec,
the privileges required to run subprocesses. If this is set to
Off the virtualhost is denied the privileges and will not
be able to run traditional CGI programs or scripts under the traditional
mod_cgi, nor similar external programs such as those
created by mod_ext_filter or
RewriteMap prog.
Note that it does not prevent CGI programs running under alternative
process and security models such as mod_fcgid, which is a recommended solution in Solaris.
If set to On or Secure, the virtual host
is permitted to run external programs and scripts as above.
Setting VHostCGIMode Secure has
the effect of denying privileges to the subprocesses, as described
for VHostSecure.
VHostCGIPrivs Directive
| Description: | Assign arbitrary privileges to subprocesses created by a virtual host. |
|---|---|
| Syntax: | VHostPrivs [+-]?privilege-name [[+-]?privilege-name] ... |
| Default: | None |
| Context: | virtual host |
| Status: | Experimental |
| Module: | mod_privileges |
| Compatibility: | Available on Solaris 10 and OpenSolaris with
non-threaded MPMs (prefork or custom MPM)
and when mod_privileges is compiled with the
BIG_SECURITY_HOLE compile-time option. |
VHostCGIPrivs can be used to assign arbitrary privileges to subprocesses created by a virtual host, as discussed
under VHostCGIMode. Each privilege-name
is the name of a Solaris privilege, such as file_setid
or sys_nfs.
A privilege-name may optionally be prefixed by + or -, which will respectively allow or deny a privilege. If used with neither + nor -, all privileges otherwise assigned to the virtualhost will be denied. You can use this to override any of the default sets and construct your own privilege set.
Security
This directive can open huge security holes in apache subprocesses, up to and including running them with root-level powers. Do not use it unless you fully understand what you are doing!
VHostGroup Directive
| Description: | Sets the Group ID under which a virtual host runs. |
|---|---|
| Syntax: | VHostGroup unix-groupid |
| Default: | Inherits the group id specified in
|
| Context: | virtual host |
| Status: | Experimental |
| Module: | mod_privileges |
| Compatibility: | Available on Solaris 10 and OpenSolaris with
non-threaded MPMs (prefork or custom MPM). |
The VHostGroup directive sets the Unix group
under which the server will process requests to a virtualhost.
The group is set before the request is processed and reset afterwards
using Solaris Privileges. Since the setting applies to the
process, this is not compatible with threaded MPMs.
Unix-group is one of:
- A group name
- Refers to the given group by name.
#followed by a group number.- Refers to a group by its number.
Security
This directive cannot be used to run apache as root! Nevertheless, it opens potential security issues similar to those discussed in the suexec documentation.
See also
VHostPrivs Directive
| Description: | Assign arbitrary privileges to a virtual host. |
|---|---|
| Syntax: | VHostPrivs [+-]?privilege-name [[+-]?privilege-name] ... |
| Default: | None |
| Context: | virtual host |
| Status: | Experimental |
| Module: | mod_privileges |
| Compatibility: | Available on Solaris 10 and OpenSolaris with
non-threaded MPMs (prefork or custom MPM).
and when mod_privileges is compiled with the
BIG_SECURITY_HOLE compile-time option. |
VHostPrivs can be used to assign arbitrary privileges to a virtual host. Each privilege-name
is the name of a Solaris privilege, such as file_setid
or sys_nfs.
A privilege-name may optionally be prefixed by + or -, which will respectively allow or deny a privilege. If used with neither + nor -, all privileges otherwise assigned to the virtualhost will be denied. You can use this to override any of the default sets and construct your own privilege set.
Security
This directive can open huge security holes in apache, up to and including running requests with root-level powers. Do not use it unless you fully understand what you are doing!
VHostSecure Directive
| Description: | Determines whether the server runs with enhanced security for the virtualhost. |
|---|---|
| Syntax: | VHostSecure On|Off |
| Default: | VHostSecure On |
| Context: | virtual host |
| Status: | Experimental |
| Module: | mod_privileges |
| Compatibility: | Available on Solaris 10 and OpenSolaris with
non-threaded MPMs (prefork or custom MPM). |
Determines whether the virtual host processes requests with security enhanced by removal of Privileges that are rarely needed in a webserver, but which are available by default to a normal Unix user and may therefore be required by modules and applications. It is recommended that you retain the default (On) unless it prevents an application running. Since the setting applies to the process, this is not compatible with threaded MPMs.
Note
If VHostSecure prevents an application
running, this may be a warning sign that the application should be
reviewed for security.
VHostUser Directive
| Description: | Sets the User ID under which a virtual host runs. |
|---|---|
| Syntax: | VHostUser unix-userid |
| Default: | Inherits the userid specified in
|
| Context: | virtual host |
| Status: | Experimental |
| Module: | mod_privileges |
| Compatibility: | Available on Solaris 10 and OpenSolaris with
non-threaded MPMs (prefork or custom MPM). |
The VHostUser directive sets the Unix userid
under which the server will process requests to a virtualhost.
The userid is set before the request is processed and reset afterwards
using Solaris Privileges. Since the setting applies to the
process, this is not compatible with threaded MPMs.
Unix-userid is one of:
- A username
- Refers to the given user by name.
#followed by a user number.- Refers to a user by its number.
Security
This directive cannot be used to run apache as root! Nevertheless, it opens potential security issues similar to those discussed in the suexec documentation.
See also
Available Languages: en
