wg-quick: linux: add support for nft and prefer it

If nft(8) is installed, use it. These rules should be identical to the
iptables-restore(8) ones, with the advantage that cleanup is easy
because we use custom table names.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

diff --git a/src/wg-quick/linux.bash b/src/wg-quick/linux.bash
index 9bfeed1b63adc15897aea3ab0544ca0c0a261984..dde02951289f0cb33d4fa335ee5a95306b714d13 100755 (executable)
--- a/src/wg-quick/linux.bash
+++ b/src/wg-quick/linux.bash
@@ -95,7 +95,7 @@ add_if() {
 del_if() {
        local table
        [[ $HAVE_SET_DNS -eq 0 ]] || unset_dns
-       [[ $HAVE_SET_IPTABLES -eq 0 ]] || remove_iptables
+       [[ $HAVE_SET_FIREWALL -eq 0 ]] || remove_firewall
        if [[ -z $TABLE || $TABLE == auto ]] && get_fwmark table && [[ $(wg show "$INTERFACE" allowed-ips) =~ /0(\ |$'\n'|$) ]]; then
                while [[ $(ip -4 rule show 2>/dev/null) == *"lookup $table"* ]]; do
                        cmd ip -4 rule delete table $table
@@ -181,22 +181,30 @@ get_fwmark() {
        return 0
 }
 
-remove_iptables() {
-       local line iptables found restore
-       for iptables in iptables ip6tables; do
-               restore="" found=0
-               while read -r line; do
-                       [[ $line == "*"* || $line == COMMIT || $line == "-A "*"-m comment --comment \"wg-quick(8) rule for $INTERFACE\""* ]] || continue
-                       [[ $line == "-A"* ]] && found=1
-                       printf -v restore '%s%s\n' "$restore" "${line/#-A/-D}"
-               done < <($iptables-save 2>/dev/null)
-               [[ $found -ne 1 ]] || echo -n "$restore" | cmd $iptables-restore -n
-       done
+remove_firewall() {
+       if type -p nft >/dev/null; then
+               local table nftcmd
+               while read -r table; do
+                       [[ $table == *" wg-quick-$INTERFACE" ]] && printf -v nftcmd '%sdelete %s\n' "$nftcmd" "$table"
+               done < <(nft list tables 2>/dev/null)
+               [[ -z $nftcmd ]] || echo -n "$nftcmd" | cmd nft -f -
+       else
+               local line iptables found restore
+               for iptables in iptables ip6tables; do
+                       restore="" found=0
+                       while read -r line; do
+                               [[ $line == "*"* || $line == COMMIT || $line == "-A "*"-m comment --comment \"wg-quick(8) rule for $INTERFACE\""* ]] || continue
+                               [[ $line == "-A"* ]] && found=1
+                               printf -v restore '%s%s\n' "$restore" "${line/#-A/-D}"
+                       done < <($iptables-save 2>/dev/null)
+                       [[ $found -ne 1 ]] || echo -n "$restore" | cmd $iptables-restore -n
+               done
+       fi
 }
 
-HAVE_SET_IPTABLES=0
+HAVE_SET_FIREWALL=0
 add_default() {
-       local table proto i iptables
+       local table i
        if ! get_fwmark table; then
                table=51820
                while [[ -n $(ip -4 route show table $table 2>/dev/null) || -n $(ip -6 route show table $table 2>/dev/null) ]]; do
@@ -204,21 +212,32 @@ add_default() {
                done
                cmd wg set "$INTERFACE" fwmark $table
        fi
-       proto=-4 iptables=iptables
-       [[ $1 == *:* ]] && proto=-6 iptables=ip6tables
+       local proto=-4 iptables=iptables pf=ip
+       [[ $1 == *:* ]] && proto=-6 iptables=ip6tables pf=ip6
        cmd ip $proto route add "$1" dev "$INTERFACE" table $table
        cmd ip $proto rule add not fwmark $table table $table
        cmd ip $proto rule add table main suppress_prefixlength 0
 
-       local marker="-m comment --comment \"wg-quick(8) rule for $INTERFACE\"" restore=$'*raw\n'
+       local marker="-m comment --comment \"wg-quick(8) rule for $INTERFACE\"" restore=$'*raw\n' nftable="wg-quick-$INTERFACE" nftcmd 
+       printf -v nftcmd '%sadd table %s %s\n' "$nftcmd" "$pf" "$nftable"
+       printf -v nftcmd '%sadd chain %s %s preraw { type filter hook prerouting priority raw; }\n' "$nftcmd" "$pf" "$nftable"
+       printf -v nftcmd '%sadd chain %s %s premangle { type filter hook prerouting priority mangle; }\n' "$nftcmd" "$pf" "$nftable"
+       printf -v nftcmd '%sadd chain %s %s postmangle { type filter hook postrouting priority mangle; }\n' "$nftcmd" "$pf" "$nftable"
        for i in "${ADDRESSES[@]}"; do
                [[ ( $proto == -4 && $i != *:* ) || ( $proto == -6 && $i == *:* ) ]] || continue
                printf -v restore '%s-I PREROUTING ! -i %s -d %s -m addrtype ! --src-type LOCAL -j DROP %s\n' "$restore" "$INTERFACE" "${i%/*}" "$marker"
+               printf -v nftcmd '%sadd rule %s %s preraw iifname != %s %s daddr %s fib saddr type != local drop\n' "$nftcmd" "$pf" "$nftable" "$INTERFACE" "$pf" "${i%/*}"
        done
        printf -v restore '%sCOMMIT\n*mangle\n-I POSTROUTING -m mark --mark %d -p udp -j CONNMARK --save-mark %s\n-I PREROUTING -p udp -j CONNMARK --restore-mark %s\nCOMMIT\n' "$restore" $table "$marker" "$marker"
+       printf -v nftcmd '%sadd rule %s %s postmangle meta l4proto udp mark %d ct mark set mark \n' "$nftcmd" "$pf" "$nftable" $table
+       printf -v nftcmd '%sadd rule %s %s premangle meta l4proto udp meta mark set ct mark \n' "$nftcmd" "$pf" "$nftable"
        [[ $proto == -4 ]] && cmd sysctl -q net.ipv4.conf.all.src_valid_mark=1
-       echo -n "$restore" | cmd $iptables-restore -n
-       HAVE_SET_IPTABLES=1
+       if type -p nft >/dev/null; then
+               echo -n "$nftcmd" | cmd nft -f -
+       else
+               echo -n "$restore" | cmd $iptables-restore -n
+       fi
+       HAVE_SET_FIREWALL=1
        return 0
 }
 
@@ -323,7 +342,7 @@ cmd_down() {
        [[ $SAVE_CONFIG -eq 0 ]] || save_config
        del_if
        unset_dns || true
-       remove_iptables || true
+       remove_firewall || true
        execute_hooks "${POST_DOWN[@]}"
 }