extensions: libip6t_frag: Add translation to nft

Add translation for frag to nftables. According to the --fraglen code:

	case O_FRAGLEN:
		/*
		 * As of Linux 3.0, the kernel does not check for
		 * fraglen at all.
		 */

In addition, the kernel code doesn't show any reference to the flag
IP6T_FRAG_LEN, so this option is deprecated and won't be translated to
nft.

Examples:

$ sudo iptables-translate -t filter -A INPUT -m frag --fragid 100:200 -j ACCEPT
nft add rule ip6 filter INPUT frag id 100-200 counter accept

$ sudo iptables-translate -t filter -A INPUT -m frag --fragid 100 --fragres --fragmore -j ACCEPT
nft add rule ip6 filter INPUT frag id 100 frag reserved 1 frag more-fragments 1 counter accept

$ sudo iptables-translate -t filter -A INPUT -m frag ! --fragid 100:200 -j ACCEPT
nft add rule ip6 filter INPUT frag id != 100-200 counter accept

$ sudo iptables-translate -t filter -A INPUT -m frag --fragid 100:200 --fraglast -j ACCEPT
nft add rule ip6 filter INPUT frag id 100-200 frag more-fragments 0 counter accept

$ sudo iptables-translate -t filter -A INPUT -m frag --fragid 100:200 --fragfirst -j ACCEPT
nft add rule ip6 filter INPUT frag id 100-200 frag frag-off 0 counter accept

$ sudo iptables-translate -t filter -A INPUT -m frag --fraglast -j ACCEPT
nft add rule ip6 filter INPUT frag more-fragments 0 counter accept

Signed-off-by: Laura Garcia Liebana <nevola@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/extensions/libip6t_frag.c b/extensions/libip6t_frag.c
index 023df627ddad2c367f30ff7e04e4779682a629a9..57487c435aa7b4790caa33e005a78366f698ff72 100644 (file)
--- a/extensions/libip6t_frag.c
+++ b/extensions/libip6t_frag.c
@@ -173,6 +173,37 @@ static void frag_save(const void *ip, const struct xt_entry_match *match)
                printf(" --fraglast");
 }
 
+static int frag_xlate(const void *ip, const struct xt_entry_match *match,
+                     struct xt_xlate *xl, int numeric)
+{
+       const struct ip6t_frag *fraginfo = (struct ip6t_frag *)match->data;
+
+       if (!(fraginfo->ids[0] == 0 && fraginfo->ids[1] == 0xFFFFFFFF)) {
+               xt_xlate_add(xl, "frag id %s",
+                            (fraginfo->invflags & IP6T_FRAG_INV_IDS) ?
+                            "!= " : "");
+               if (fraginfo->ids[0] != fraginfo->ids[1])
+                       xt_xlate_add(xl, "%u-%u ", fraginfo->ids[0],
+                                    fraginfo->ids[1]);
+               else
+                       xt_xlate_add(xl, "%u ", fraginfo->ids[0]);
+       }
+
+       if (fraginfo->flags & IP6T_FRAG_RES)
+               xt_xlate_add(xl, "frag reserved 1 ");
+
+       if (fraginfo->flags & IP6T_FRAG_FST)
+               xt_xlate_add(xl, "frag frag-off 0 ");
+
+       if (fraginfo->flags & IP6T_FRAG_MF)
+               xt_xlate_add(xl, "frag more-fragments 1 ");
+
+       if (fraginfo->flags & IP6T_FRAG_NMF)
+               xt_xlate_add(xl, "frag more-fragments 0 ");
+
+       return 1;
+}
+
 static struct xtables_match frag_mt6_reg = {
        .name          = "frag",
        .version       = XTABLES_VERSION,
@@ -185,6 +216,7 @@ static struct xtables_match frag_mt6_reg = {
        .save          = frag_save,
        .x6_parse      = frag_parse,
        .x6_options    = frag_opts,
+       .xlate         = frag_xlate,
 };
 
 void