Please, a sudo clone with regex support

Great! This is what I needed.

The aim is to allow admins to delegate accurate least privilege access with ease. There are times when what is intended to be executed can be expressed easily with a regex to expose only what is needed and nothing more.

How do I install it

A simple install:

  git clone https://gitlab.com/edneville/please.git
  cd please
  cargo test && cargo build --release \
  && cp target/release/please target/release/pleaseedit /usr/local/bin \
  && chown root:root /usr/local/bin/please /usr/local/bin/pleaseedit
  && chmod 4755 /usr/local/bin/please /usr/local/bin/pleaseedit

Optionally, set sudo as an alias of please:

alias sudo="please"
alias sudoedit="pleaseedit"

How do I set it up

Next, configure your /etc/please.ini similar to this, replace user names with appropriate values. One of the simplest, that does not require password authentication can be defined as follows, assuming the user is ed:

The options are as follows:

include and includedir will override mandatory arguments.

Using a greedy .* for the regex field will be as good as saying the rule should match any command. In previous releases there was no anchor (^ and $) however, it seems more sensible to follow find's approach and insist that there are anchors around the regex. This avoids /bin/bash matching /home/user/bin/bash unless the rule permits something like /home/%{USER}/bin/bash.

If a include directive is met, no other enties in the section will be processed. The same goes for includedir.

The ordering of rules matters. The last match will win. Set permit=false if you wish to exclude something, but this should be very rare as the permit should be against a regex rather than using a positive and then a negative match. A rule of best practice is to avoid a fail open and then try and exclude most of the universe.

For example, using the two entries below:

[ed_root_du]
name=ed
target=root
permit=true
regex = ^(/usr)?/bin/du\s.*
require_pass=false

[ed_postgres]
name=ed
target=postgres
permit=true
regex = /bin/bash
require_pass=false

Would permit running du, as /usr/bin/du or /bin/du as root:

$ please du /home/*

And would also permit running a bash shell as postgres:

$ please -t postgres /bin/bash
postgres$

Date ranges

For large environments it is not unusual for a third party to require access during a short time frame for debugging. To accommodate this there are the notbefore and notafter time brackets. These can be either YYYYMMDD or YYYYMMDDHHMMSS.

The whole day is considered when using the shorter date form of YYYYMMDD.

Many enterprises may wish to permit access to a user for a limited time only, even if that individual is in the role permanently.

Date matches

Another date type is the datematch item, this constrains sections to a regex match against the date string Day Mon HH:MM:SS UTC Year.

You can permit some a group of users to perform some house keeping on a Monday:

[l2_housekeeping]
name=l2users
group=true
target=root
permit=true
regex = /usr/local/housekeeping/.*
datematch = ^Mon.*

pleaseedit

pleaseedit enables editing of files as another user. Enable editing rather than execution with edit=true. The first argument will be passed to EDITOR.

This is performed as follows:

1. user runs edit as pleaseedit -u root /etc/fstab
2. /etc/fstab is copied to /tmp/fstab.pleaseedit.$USER
3. user's EDITOR is executed against /tmp/fstab.pleaseedit.$USER
4. if EDITOR exits 0, and editcmd exits 0, then /tmp/fstab.pleaseedit.$USER is copied to /etc/fstab.pleaseedit.$USER
5. /etc/fstab.pleaseedit.$USER is set as root owned and renamed to /etc/fstab

editcmd

editcmd can be used prior to the tmp edit file move to the source location. This can be used to test configuration files are valid prior to renaming in place.

For something similar to apache, consider copying the config tree to a tmp directory before running the test to accommodate includes.

Other examples

Members of the audio group may remove temporary users that an application may not have cleaned up in the form of username_tmp.<10 random alphanumerics> using userdel:

[user_remove_tmp_user]
name = audio
group = true
permit = true
require_pass = false
regex = /usr/sbin/userdel -f -r %{USER}_tmp\.[a-zA-Z0-9]{10}

How about, for the purpose of housekeeping, some users may be permitted to destroy zfs snapshots that look roughly like they're date stamped:

[user_remove_snapshots]
name = data
group = true
permit = true
require_pass = false
regex = /usr/sbin/zfs destroy storage/photos@\d{8}T\d{6}

To list what you may or may not do:

$ please -l
You may run the following:
  file: /etc/please.ini
    ed_root_list:root: ^.*$
You may edit the following:
  file: /etc/please.ini
    ed_edit_ini:root: ^/etc/please.ini$

The above output shows that I may run anything and may edit the please.ini configuration.

Or, perhaps any user who's name starts admin may execute useradd and userdel:

[admin_users]
name = admin_\S+
permit = true
require_pass = false
regex = /usr/sbin/user(add|del)\s.*

Files

/etc/please.ini

Big installs

For big installs I suggest consider the following:

Consolidate

Where you can use groups when all member least privilege matches the set. It is best here to consider that people often perform the same role.

Central configuration considerations

To avoid single points of failure in a service, ini configuration should be generated in a single location and pushed to installs. ini files parse very quickly whilst accessing LDAP is not only slower but also error prone.

It could be possible to use caching, but a form of positive (correct match) and negative (incorrect match) would be required. 10,000 computers with hundreds of active users performing lookups against an LDAP server could be problematic.

For these reasons I prefer rsync configuration as the protocol is highly efficient and reduces network transfer overall.

Contributions

I welcome pull requests with open arms.

Locations

The source code for this project is currently hosted on gitlab and mirrored to github. There is a crate on crates.io. It also has a homepage where other project information is kept.

Why pleaser in some circles?

This project is named "please". In some places that project name was used by others for other things. Some packages will be named pleaser, some will be named please. The only important thing is if you wish someone to make you a sandwich, just say "please" first.

Todo

[ ] docker image for testing
[ ] plugins/modules
[ ] packages