One Firefox profile per site (extras/firefox-profiles/new-profile.sh)

SYNOPSIS

firefox --profiles                        the profiles there are: command, address, choices
firefox --new-profile [NAME URL [...]]    make one (asks, without NAME and URL); Tab completes
firefox --remove-profile NAME             remove one (asks before deleting its logins and user)
firefox --profile NAME [URL]              open one (its own command, below, does the same)

bash ~/wren/extras/firefox-profiles/new-profile.sh                      the same, by the script: asks
bash ~/wren/extras/firefox-profiles/new-profile.sh NAME URL [--fast-js] [--hide-toolbars] [--no-sound] [--keep-cookies] [--ublock-standard]
bash ~/wren/extras/firefox-profiles/new-profile.sh --remove NAME        asks before deleting its logins and user
bash ~/wren/extras/firefox-profiles/new-profile.sh --manual             print the manual steps below

NAME                open that site in its own profile (Super+d finds it too);
                    firefox-NAME when a program is called NAME already
  the window shows only the page: Alt+Left back, Alt+Right forward, F5 reload, Ctrl+W close

For a site you stay logged in to (a bank, email, shopping), a Firefox of its own with a command named after it (github; firefox-NAME when a program has that name already, since ~/.local/bin comes first and the command would stand in for it): its own cookies, logins and history, run as its own locked-down Linux user, fx-NAME, like the sandboxed Firefox's (extras/firefox-sandbox.sh, which it needs), so a hacked page in one profile reaches neither your files nor the other profiles.

Only the clipboard and ~/Downloads/NAME are shared with you. Its address and choices are in /etc/wren/firefox-profiles/NAME.conf, a file only root can write. Its tabs and address bar are shown, so you can see which site you're on; --hide-toolbars shows only the page.

--no-sound keeps it silent (a bank needs no sound). Its cookies and site data are deleted when it closes, so you log in each time (KeePassXC fills it in) and the site can't recognise you from one visit to the next; --keep-cookies keeps them, to stay logged in. Run without NAME and URL it asks, fast JavaScript and sound too. A site you'd rather stay logged in to can also be kept in Firefox's own Settings > Privacy & Security > Manage Exceptions (Allow), which stays.

--fast-js turns the JavaScript JIT back on for that profile only, for heavy web apps.

--ublock-standard gives the profile's site uBlock's standard mode (ublock-allow SITE), for a site that breaks in medium mode, as GitHub does: other sites' scripts and frames run there, and the filter lists still block ads, trackers and known malware sites. uBlock's settings are shared by every Firefox, so that site gets standard mode in each of them; ublock-allow --remove SITE undoes it.

LIMITS

• Everything in the sandboxed Firefox's LIMITS applies to each profile.
• With --hide-toolbars there is no address bar to show which page you're on: follow only links you expect.
• --fast-js brings back what most serious Firefox exploits target, for that site.
• A profile's command takes a name no program has when it is made. A package installed later with the same name is hidden behind it until you remove the profile (type -a NAME shows both).
• Kept cookies (--keep-cookies) let the site recognise you on every visit; that is how you stay logged in.

MANUAL INSTALL

Set up the sandboxed Firefox first (firefox-sandbox.md). These steps make a profile called bank; use your own name (lowercase letters, digits and dashes) and address.

NAME=bank URL=https://mybank.example
# Its user: in the sandboxed Firefox's group, no password, no login shell,
# a home only it can enter; render for the GPU's render node
sudo mkdir -p /var/lib/wren-fx
sudo useradd --system --gid wren-fx --create-home --home-dir /var/lib/wren-fx/$NAME --shell /usr/sbin/nologin --comment "Wren Linux Firefox profile $NAME" fx-$NAME
sudo usermod --lock --shell /usr/sbin/nologin fx-$NAME
sudo chmod 0700 /var/lib/wren-fx/$NAME
sudo usermod -aG render fx-$NAME

# Its address and choices, in a file only root can write (fast_js=yes for the
# JIT, toolbars=shown for tabs and the address bar, sound=no for silence,
# cookies=keep to keep cookies and site data when it closes)
sudo install -d -o root -g root -m 0755 /etc/wren/firefox-profiles
printf 'url=%s\nfast_js=no\ntoolbars=shown\nsound=yes\ncookies=delete\n' "$URL" | sudo tee /etc/wren/firefox-profiles/$NAME.conf

# Your user may run the session script, and nothing else, as fx-NAME. visudo
# checks the rule first: never put a rule in /etc/sudoers.d it hasn't passed.
printf '%s ALL=(fx-%s) NOPASSWD: /usr/local/libexec/firefox-session\n' "$(id -un)" "$NAME" >/tmp/wren-fx-$NAME
sudo visudo -cf /tmp/wren-fx-$NAME
sudo install -o root -g root -m 0440 /tmp/wren-fx-$NAME /etc/sudoers.d/wren-fx-$NAME
rm /tmp/wren-fx-$NAME

# The command, named NAME: first check no program has that name (this must
# print nothing; if it prints anything, call the command firefox-$NAME instead)
type -a $NAME
mkdir -p ~/.local/bin
printf '#!/bin/sh\n# Written by Wren Linux extras/firefox-profiles/new-profile.sh\nexec /usr/local/bin/firefox --profile %s "$@"\n' "$NAME" >~/.local/bin/$NAME
chmod +x ~/.local/bin/$NAME
$NAME

To undo (files it downloaded stay in ~/Downloads/NAME):

NAME=bank
# The command (NAME or firefox-NAME: only the one Wren Linux wrote), the
# sudo rule and its settings
for c in ~/.local/bin/$NAME ~/.local/bin/firefox-$NAME; do grep -qs 'Written by Wren Linux extras/firefox-profiles' "$c" && rm "$c"; done
sudo rm /etc/sudoers.d/wren-fx-$NAME /etc/wren/firefox-profiles/$NAME.conf
# Its user, and its logins and history
sudo pkill -KILL -u fx-$NAME
sudo userdel fx-$NAME
sudo rm -rf /var/lib/wren-fx/$NAME /dev/shm/fx-$NAME-run