branches/gsoc08-privileges

gsoc08-privileges is pmagrath's development branch for Google Summer of Code 2008.

Summary

To implement facility to reduce need to execute MacPorts as root.

Current Status

On the 11th August, a Beta release was announced on macports-dev and a couple of bugs were shaken out. The code base for the branch is now reasonably well tested and about ready for integration into trunk where it can be tested more fully before the next point release of MacPorts. As such, on the 18th August 2008 (GSoC "pencils down" date) I termed it to be at "Release Candidate" stage.

Use Cases

Use Case 1: Current Situation with privilege descalation. Prefix is /opt/local. Root owns prefix. Fetch, build, extract, etc are done in per-user location (~/.macports) and do not require root privileges. Root privileges needed to install. Drop privileges when not needed if started with sudo.

Use Case 2: --with-no-root-privileges. Prefix is usually ~/.macports/opt/local (must be specified with --prefix). User owns prefix. No root privileges needed. Ports requiring root privileges (new user accounts, daemons etc.) cannot be installed without a sudo. It is necessary to use a --prefix with --with-no-root-privileges as the default --prefix isn't modified from /opt/local when --with-no-root-privileges is specified.

Use Case 3: --with-shared-directory. Prefix is /opt/local. Root owns prefix but shares full read write with a macports group. All members of macports group can install all packages that only effect the /opt/local hierarchy. Root privileges only needed for installs that effect directories outside the prefix. Port maintainers are responsible for designating this with the "install.asroot" option. Drop privileges when not needed.

The Plan

The proposal is to implement a number of improvements to the MacPorts code base in order to reduce the need to execute MacPorts with root privileges.

Reduce need for actions to run as root

MacPorts operations which do not explicitly need root privileges will be re-coded so that they will run with normal user privileges. Examples would include fetching, extracting and building the port.

Pretty much done. fetch, checksum, extract, patch, configure and build should now work fine. Operations are executed in ~/.macports/opt/.

Portfile Format

The portfile format shall be extended with an additional attribute to mark those ports that can not be installed without root privileges, such as those requiring StartupItems.

I've added the following new options to the Portfile format: patch.asroot, build.asroot, configure.asroot, destroot.asroot, and install.asroot. These take a boolean (yes/no) value. The default for all is no.

Privilege Escaltion

I would feel that the best behavior for if MacPorts is requested to perform a privileged operation for a port, if it currently has no privileged access would be for the user to be given the choice of elevating privileges (by evoking sudo), or aborting.

This has now been largely implemented. A special flag is now thrown ($errorisprivileges) when a port install (or other action) fails due to insufficient privileges. MacPorts will then assemble a sudo command to complete the action with and execute it, prompting the user to enter his/her password to do so.

MacPorts Group

It would be a good idea to create an additional group macports which users are allowed to run any port command. So /opt/local would be owned by the group macports with g+rw. (Gentoo's portage does something like this.)

This will allow users who are members of the new macports group to have full write permissions to /opt and its subfolders, and hence to install ports which only affect that hierarchy to install those ports without requiring root privileges.

I have added a "make group" command to the Makefile and a "--with-shared-directory" switch to the configure script. Running "make group" will create a macports group. "--with-shared-directory" will let let the group specified by "--with-install-group" have full read write access to the /opt/local hierarchy.

Privilege Dropping

Examine how we could drop root privileges for building. So we still run port using sudo, but for the actual building root privileges are dropped and the configure/build phase runs with the privileges of the current user only (or of some new unprivileged macports user?). Of course this needs investigation how the permissions inside the workpath need to be set to accomplish this.

Most actions are now performed using user privileges, up to and including the destroot stage. For install, the original root privileges are recovered and the install takes place as per usual. To the user, this is seamless and the only difference is that the build files get put in ~/.macports/opt rather than /opt. The user account to use when privileges are dropped can be set in macports.conf post-install or with the --with-macports-user=USER option on the ./configure switch. The default value is the user who installs MacPorts.

Install MacPorts in your home directory easily

Modify some of the configure scripts. Currently, if you want to install a MacPorts tree into your home, you need to configure it like this manually:

./configure \ --prefix=~/macports \ --with-install-user=foo \ --with-install-group=foo \ --with-tclpackage=~/Library/Tcl

It'd be great if this could be done with one switch only. For example:

./configure \ --prefix=~/macports \ --without-root-privileges

This will allow users to install packages into their own ~/.macports/opt instead of /opt when non root users wish to install ports for their own use only.

Done. A switch called "--with-no-root-privileges" has been added. Note that --prefix is a built in Autoconf macro that requires an absolute path. As such an example would be "./configure --prefix=/Users/{your-user-name-here}/.macports --with-no-root-privileges"

Goals

1) Implementation of the improvements outlined above.
2) Ability to easily install common packages without root privileges.
3) (Stretch) Easy use of MacPorts without root user account activation.

Related Resources

​http://thread.gmane.org/gmane.os.opendarwin.darwinports/16973/focus=17026