mirror of
https://github.com/open-webui/open-terminal.git
synced 2026-11-04 08:10:53 +00:00
217 lines
8.1 KiB
Bash
Executable File
217 lines
8.1 KiB
Bash
Executable File
#!/bin/sh
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set -e
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# ============================================================================
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# Open Terminal — Hardened Entrypoint (Slim & Alpine)
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# ============================================================================
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#
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# This entrypoint is shared by both the slim (Debian) and Alpine images.
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# It handles:
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# 1. Docker-secrets support (_FILE env vars)
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# 2. Home directory permissions & dotfile seeding
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# 3. Network egress filtering (iptables + dnsmasq whitelist)
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#
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# What it does NOT do (by design):
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# ✘ No runtime apt/pip package installation
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# ✘ No Docker socket detection
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# ✘ No sudo — privilege drop uses gosu (Debian) or su-exec (Alpine)
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#
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# ============================================================================
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# ── Helper: Docker-secrets _FILE resolution ────────────────────────────────
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#
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# Follows the convention from the official PostgreSQL image.
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# If OPEN_TERMINAL_API_KEY_FILE is set, its contents become the key.
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#
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file_env() {
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local var="$1"
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local fileVar="${var}_FILE"
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local def="${2:-}"
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local val="$def"
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eval local currentVal="\${$var:-}"
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eval local fileVal="\${$fileVar:-}"
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eval local varIsSet="\${$var+set}"
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eval local fileIsSet="\${$fileVar+set}"
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if [ "$varIsSet" = "set" ] && [ "$fileIsSet" = "set" ]; then
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printf >&2 'error: both %s and %s are set (but are exclusive)\n' "$var" "$fileVar"
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exit 1
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fi
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if [ -n "$currentVal" ]; then
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val="$currentVal"
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elif [ -n "$fileVal" ]; then
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val="$(cat "$fileVal")"
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fi
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export "$var"="$val"
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unset "$fileVar"
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}
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file_env 'OPEN_TERMINAL_API_KEY'
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# ── Helper: drop privileges to "user" ─────────────────────────────────────
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#
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# Detects gosu (Debian) vs su-exec (Alpine) automatically.
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# Both do the same thing: exec a command as a different user.
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#
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drop_to_user() {
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if command -v gosu >/dev/null 2>&1; then
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exec gosu user "$@"
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elif command -v su-exec >/dev/null 2>&1; then
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exec su-exec user "$@"
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else
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# Fallback: already running as the right user
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exec "$@"
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fi
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}
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# ── Home directory setup ──────────────────────────────────────────────────
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#
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# When /home/user is bind-mounted empty, Docker doesn't populate it with
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# the image contents. We seed essential dotfiles so bash works properly.
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#
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fix_home() {
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local home="/home/user"
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# Fix ownership if the mount changed it (works on both GNU and BusyBox stat)
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local owner_uid
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owner_uid=$(stat -c '%u' "$home" 2>/dev/null) || owner_uid=$(stat -f '%u' "$home" 2>/dev/null) || owner_uid="1000"
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if [ "$owner_uid" != "1000" ]; then
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chown -R user:user "$home" 2>/dev/null || true
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fi
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# Seed bashrc / profile from skeleton if missing
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if [ ! -f "$home/.bashrc" ]; then
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if [ -f /etc/skel/.bashrc ]; then
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cp /etc/skel/.bashrc "$home/.bashrc" 2>/dev/null || true
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fi
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fi
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if [ ! -f "$home/.profile" ]; then
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if [ -f /etc/skel/.profile ]; then
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cp /etc/skel/.profile "$home/.profile" 2>/dev/null || true
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fi
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fi
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mkdir -p "$home/.local/bin"
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chown -R user:user "$home" 2>/dev/null || true
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}
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# ── Network egress filtering ──────────────────────────────────────────────
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#
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# OPEN_TERMINAL_ALLOWED_DOMAINS unset → full internet access
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# OPEN_TERMINAL_ALLOWED_DOMAINS="" → block ALL outbound traffic
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# OPEN_TERMINAL_ALLOWED_DOMAINS="a,b" → DNS whitelist via dnsmasq
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#
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# When restricted, a local dnsmasq resolves only whitelisted domains.
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# iptables blocks all other outbound traffic. CAP_NET_ADMIN is then
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# permanently dropped so the rules can't be undone from inside.
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#
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setup_egress_firewall() {
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if ! command -v iptables >/dev/null 2>&1; then
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echo "ERROR: iptables is required for egress filtering" >&2
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exit 1
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fi
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# Flush any prior OUTPUT rules
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iptables -F OUTPUT 2>/dev/null || true
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# Capture upstream DNS before replacing resolv.conf, including in deny-all mode.
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UPSTREAM_DNS=$(grep -m1 '^nameserver' /etc/resolv.conf | awk '{print $2}')
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UPSTREAM_DNS="${UPSTREAM_DNS:-8.8.8.8}"
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if [ -z "$OPEN_TERMINAL_ALLOWED_DOMAINS" ]; then
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# ── Deny-all mode ──────────────────────────────────────────────
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echo "Egress: blocking ALL outbound traffic"
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else
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# ── Restricted mode (DNS whitelist + ipset) ────────────────────
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echo "Egress: DNS whitelist — $OPEN_TERMINAL_ALLOWED_DOMAINS"
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# Create ipset for dynamically resolved IPs
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ipset create allowed hash:ip -exist
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# Generate dnsmasq config:
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# - NXDOMAIN for everything by default
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# - Forward allowed domains to upstream DNS
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# - Auto-add resolved IPs to the 'allowed' ipset
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mkdir -p /etc/dnsmasq.d
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{
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echo "user=dnsmasq"
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echo "no-resolv"
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echo "no-hosts"
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echo "listen-address=127.0.0.1"
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echo "port=53"
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echo "address=/#/" # NXDOMAIN for everything by default
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# Process each comma-separated domain
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echo "$OPEN_TERMINAL_ALLOWED_DOMAINS" | tr ',' '\n' | while read -r domain; do
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domain=$(echo "$domain" | sed 's/^[[:space:]]*//;s/[[:space:]]*$//')
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[ -z "$domain" ] && continue
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# Strip wildcard prefix — dnsmasq matches all subdomains natively
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domain="${domain#\*.}"
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echo "server=/${domain}/${UPSTREAM_DNS}"
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echo "ipset=/${domain}/allowed"
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echo " ✓ ${domain} (+ subdomains)" >&2
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done
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} > /etc/dnsmasq.d/egress.conf
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# Start dnsmasq as a background daemon
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dnsmasq --conf-file=/etc/dnsmasq.d/egress.conf
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echo "dnsmasq started (upstream: ${UPSTREAM_DNS})"
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# Point the container at our local resolver
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echo "nameserver 127.0.0.1" > /etc/resolv.conf
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# Match the original destination: Docker rewrites its embedded DNS port.
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# Check DNS before allowing loopback or established connections.
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for protocol in udp tcp; do
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iptables -A OUTPUT -p "$protocol" -m conntrack --ctdir ORIGINAL \
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--ctorigdst "$UPSTREAM_DNS" --ctorigdstport 53 \
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-m owner --uid-owner dnsmasq -j ACCEPT
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iptables -A OUTPUT -p "$protocol" -m conntrack --ctdir ORIGINAL \
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--ctorigdst 127.0.0.1 --ctorigdstport 53 -j ACCEPT
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done
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fi
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# Also block Docker's loopback DNS in deny-all mode.
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for protocol in udp tcp; do
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iptables -A OUTPUT -p "$protocol" -m conntrack --ctdir ORIGINAL \
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--ctorigdstport 53 -j DROP
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done
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# Prevent direct access to Docker DNS's translated high ports as well.
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iptables -A OUTPUT -o lo -d "$UPSTREAM_DNS" -j DROP
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iptables -A OUTPUT -o lo -j ACCEPT
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iptables -A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
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if [ -n "$OPEN_TERMINAL_ALLOWED_DOMAINS" ]; then
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iptables -A OUTPUT -m set --match-set allowed dst -j ACCEPT
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fi
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iptables -A OUTPUT -j DROP
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echo "Egress firewall active — dropping CAP_NET_ADMIN permanently"
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}
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# ============================================================================
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# Main
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# ============================================================================
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fix_home
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# Export env vars for the app user (since we're running as root, these
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# won't be inherited automatically).
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export HOME="/home/user"
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export PATH="/home/user/.local/bin:${PATH}"
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# Call setup outside a conditional so failures stop startup under set -e.
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if [ "${OPEN_TERMINAL_ALLOWED_DOMAINS+set}" = "set" ]; then
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setup_egress_firewall
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exec capsh --drop=cap_net_admin --user=user -- -c 'exec open-terminal "$@"' -- "$@"
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else
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drop_to_user open-terminal "$@"
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fi
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