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+++ readme.md
+xodo
+====
+
+Execute commands in Xorg as another user.
+
+## Getting started
+
+```
+$ ftp https://raw.githubusercontent.com/garotosopa/xodo/master/xodo.sh
+$ chmod +x xodo.sh
+$ doas mv -i xodo.sh /usr/local/bin/xodo
+```
+
+If your user doesn't have doas privileges, become root and copy the file accordingly.
+
+## Usage
+
+```
+$ doas xodo --setup firefox
+$ xodo firefox
+```
+
+If your user doesn't have doas privileges, become root and setup xodo with the --for option as described further below.
+
+## Command-line options
+
+```
+xodo <command> [--as <user>]
+xodo --setup <command> [--as <user>] [--for <user>]
+xodo --help
+```
+
+## Description
+
+The xodo utility authorizes a conventioned user in the form of $user-$command to connect to the active Xorg display, then executes the given command as this other user.
+
+This script has been developed to avoid a potential vulnerability in a desktop program to compromise anything else other than the program itself. To accomplish this, each program is executed as a different user that connects to the active Xorg display, using an Xauthority cookie file that's setup automatically by xodo.
+
+Before using xodo to execute commands, the unprivileged user must be created first, either manually or using the --setup option. Besides adding the new user, the main user that's going to execute xodo must be allowed in doas.conf to execute the given command as the other user. This is already taken care of when using xodo's --setup option.
+
+The command argument is mandatory and can either be an absolute or relative path, or just the command basename. In this latter case, the command is assumed to be in the current PATH. Arguments to the command being executed are not supported yet.
+
+The options are as follows:
+
+### --as <user>
+
+When specified, this is the unprivileged user as which the command is going to be executed, or the user that's going to be created when invoked with the --setup option.
+
+When ommitted, the convention assumes $user-$command instead. In this case, $USER environment variable is assumed. During setup, this can be overridden with the --for option.
+
+### --for <user>
+
+When specified, this is the user that will be allowed to execute the command as another user. This options is only used with --setup.
+
+When ommitted, the $USER environment variable is used.
+
+### --help
+### -h
+
+Display basic usage syntax.
+
+### --setup <command>
+
+Adds a new user and authorizes the current user in doas.conf to execute the given command as the new unprivileged user. The current user is also added to the new user's group.
+
+If the new user already exists, no user is added and the current user is not added to any group, but doas.conf still gets a new entry.
+
+Options --as and --for overrides the username being created, and the existing user that will be allowed to execute the command, respectively.
+
+This option must be used as root, as it calls useradd and usermod, and also appends an entry to doas.conf.
+
+## Examples
+
+Configure an unprivileged user for Mike to execute Firefox:
+
+```
+mike$ doas xodo --setup firefox
+```
+
+This assumes that Mike is permitted in doas.conf to execute xodo as root. Otherwise, root should be used directly for setting this up for Mike:
+
+```
+root# xodo --setup firefox --for mike
+```
+
+Either way, now Mike can execute Firefox as the user mike-firefox, so
+that any vulnerability in Firefox wouldn't compromise Mike's files:
+
+```
+mike$ xodo firefox
+```
+
+To create an unprivileged user different than the $user-$command convetion, use the --as option during setup:
+
+```
+root# xodo --setup firefox --for mike --as mike-work
+```
+
+Then specify this different user when executing xodo:
+
+```
+mike$ xodo firefox --as mike-work
+```
+
+## See also
+
+* [doas(1)](http://man.openbsd.org/OpenBSD-current/man1/doas.1)
+* [doas.conf(5)](http://man.openbsd.org/OpenBSD-current/man5/doas.conf.5)
+* [xauth(1)](http://man.openbsd.org/OpenBSD-current/man1/xauth.1)
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--- /dev/null
+++ xodo.sh
+#!/bin/sh
+
+set -e
+
+main() {
+ if [[ "$1" == "" ]]; then
+ echo "Missing arguments" >&2
+ display_usage >&2
+ return 1
+ elif [[ "$1" == "-h" ]] || [[ "$1" == "--help" ]]; then
+ display_usage
+ elif [[ "$1" == "--setup" ]]; then
+ shift
+ setup $@
+ else
+ execute $@
+ fi
+}
+
+execute() {
+ command=`which -- $1`
+ basename=`basename $command`
+ asuser=$USER-$basename
+
+ shift
+
+ if [[ "$1" == "--as" ]]; then
+ if [[ "$2" == "" ]]; then
+ echo "--as user not specified" >&2
+ display_usage >&2
+ return 1
+ fi
+
+ asuser=$2
+ elif [[ "$1" != "" ]]; then
+ echo "Invalid argument: $1" >&2
+ display_usage
+ return 1
+ fi
+
+ userinfo=`userinfo $asuser`
+ otherhome=`echo "$userinfo" | grep ^dir | sed s/^dir//`
+ authfile=$otherhome/.Xauthority
+
+ touch $authfile
+ xauth -f $authfile generate $DISPLAY . trusted
+ chgrp $asuser $authfile
+ chmod g+r $authfile
+
+ cd $otherhome
+ exec doas -u $asuser $command
+}
+
+setup() {
+ if [[ "$1" == "" ]]; then
+ echo "Command not specified" >&2
+ display_usage >&2
+ return 1
+ fi
+
+ command=`which -- $1`
+ basename=`basename $command`
+
+ shift
+
+ while [[ "$1" != "" ]]; do
+ if [[ "$1" == "--as" ]]; then
+ if [[ "$2" == "" ]]; then
+ echo "--as user not specified" >&2
+ display_usage >&2
+ return 1
+ elif [[ "$asuser" != "" ]]; then
+ echo "--as user specified twice" >&2
+ display_usage >&2
+ return 1
+ fi
+
+ asuser=$2
+ shift
+ shift
+ elif [[ "$1" == "--for" ]]; then
+ if [[ "$2" == "" ]]; then
+ echo "--for user not specified" >&2
+ display_usage >&2
+ return 1
+ elif [[ "$foruser" != "" ]]; then
+ echo "--for user specified twice" >&2
+ display_usage >&2
+ return 1
+ fi
+
+ foruser=$2
+ shift
+ shift
+ else
+ echo "Invalid argument: $1" >&2
+ display_usage
+ return 1
+ fi
+ done
+
+ asuser=${asuser-$USER-$basename}
+ foruser=${foruser-$USER}
+
+ echo "Setup $command as $asuser for $foruser" >&2
+ echo "Not implemented yet" >&2
+ return 1
+}
+
+display_usage() {
+ echo "usage: xodo <command> [--as <user>]"
+ echo " xodo --setup <command> [--as <user>] [--for <user>]"
+ echo " xodo --help"
+}
+
+main $@
