Hi Ahmed,

On Fri, Dec 29, 2017 at 12:07:52PM +0100, Ahmed Abdelsalam wrote:

Please, add this in SPDX format instead.

See include/uapi/linux/netfilter/xt_owner.h for instance.

+#ifndef _IP6T_SRH_H
+#define _IP6T_SRH_H
+
+#include <linux/types.h>
+#include <linux/netfilter.h>
+
+/* Values for "mt_flags" field in struct ip6t_srh */
+#define IP6T_SRH_NEXTHDR        0x0001
+#define IP6T_SRH_LEN_EQ         0x0002
+#define IP6T_SRH_LEN_GT         0x0004
+#define IP6T_SRH_LEN_LT         0x0008
+#define IP6T_SRH_SEGS_EQ        0x0010
+#define IP6T_SRH_SEGS_GT        0x0020
+#define IP6T_SRH_SEGS_LT        0x0040
+#define IP6T_SRH_LAST_EQ        0x0080
+#define IP6T_SRH_LAST_GT        0x0100
+#define IP6T_SRH_LAST_LT        0x0200
+#define IP6T_SRH_TAG            0x0400
+#define IP6T_SRH_MASK           0x07FF
+
+/* Values for "mt_invflags" field in struct ip6t_srh */
+#define IP6T_SRH_INV_NEXTHDR    0x0001
+#define IP6T_SRH_INV_LEN_EQ     0x0002
+#define IP6T_SRH_INV_LEN_GT     0x0004
+#define IP6T_SRH_INV_LEN_LT     0x0008
+#define IP6T_SRH_INV_SEGS_EQ    0x0010
+#define IP6T_SRH_INV_SEGS_GT    0x0020
+#define IP6T_SRH_INV_SEGS_LT    0x0040
+#define IP6T_SRH_INV_LAST_EQ    0x0080
+#define IP6T_SRH_INV_LAST_GT    0x0100
+#define IP6T_SRH_INV_LAST_LT    0x0200
+#define IP6T_SRH_INV_TAG        0x0400
+#define IP6T_SRH_INV_MASK       0x07FF

Looking at all these EQ, GT, LT... I think this should be very easy to
implement in nf_tables with no kernel changes.

You only need to add the protocol definition to:

nftables/src/exthdr.c

Would you have a look into this? This would be very much appreciated
to we keep nftables in sync with what we have in iptables.

Not a deal breaker, but modern code usually places these MODULE_*
lines at the end of the file.

+
+/* Test a struct->mt_invflags and a boolean for inequality */
+#define NF_SRH_INVF(ptr, flag, boolean)	\
+	((boolean) ^ !!((ptr)->mt_invflags & (flag)))
+
+static bool srh_mt6(const struct sk_buff *skb, struct xt_action_param *par)
+{
+	const struct ip6t_srh *srhinfo = par->matchinfo;
+	struct ipv6_sr_hdr *srh;
+	struct ipv6_sr_hdr _srh;
+	int hdrlen, srhoff = 0;
+
+	if (ipv6_find_hdr(skb, &srhoff, IPPROTO_ROUTING, NULL, NULL) < 0)
+		return false;
+
+	srh = skb_header_pointer(skb, srhoff, sizeof(_srh), &_srh);
+

Remove unnecessary line break.

+	if (!srh)
+		return false;
+
+	hdrlen = ipv6_optlen(srh);
+	if (skb->len - srhoff < hdrlen)
+		return false;
+
+	if (srh->type != IPV6_SRCRT_TYPE_4)
+		return false;
+
+	if (srh->segments_left > srh->first_segment)
+		return false;
+
+	/* Next Header matching */
+	if (srhinfo->mt_flags & IP6T_SRH_NEXTHDR)
+		if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_NEXTHDR,
+				!(srh->nexthdr == srhinfo->next_hdr)))
+			return false;
+
+	/* Header Extension Length matching */
+	if (srhinfo->mt_flags & IP6T_SRH_LEN_EQ)
+		if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LEN_EQ,
+				!(srh->hdrlen == srhinfo->hdr_len)))
+			return false;
+
+	if (srhinfo->mt_flags & IP6T_SRH_LEN_GT)
+		if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LEN_GT,
+				!(srh->hdrlen > srhinfo->hdr_len)))
+			return false;
+
+	if (srhinfo->mt_flags & IP6T_SRH_LEN_LT)
+		if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LEN_LT,
+				!(srh->hdrlen < srhinfo->hdr_len)))
+			return false;
+
+	/* Segments Left matching */
+	if (srhinfo->mt_flags & IP6T_SRH_SEGS_EQ)
+		if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_SEGS_EQ,
+				!(srh->segments_left == srhinfo->segs_left)))
+			return false;
+
+	if (srhinfo->mt_flags & IP6T_SRH_SEGS_GT)
+		if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_SEGS_GT,
+				!(srh->segments_left > srhinfo->segs_left)))
+			return false;
+
+	if (srhinfo->mt_flags & IP6T_SRH_SEGS_LT)
+		if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_SEGS_LT,
+				!(srh->segments_left < srhinfo->segs_left)))
+			return false;
+
+	/**
+	 * Last Entry matching
+	 * Last_Entry field was introduced in revision 6 of the SRH draft.
+	 * It was called First_Segment in the previous revision
+	 */
+	if (srhinfo->mt_flags & IP6T_SRH_LAST_EQ)
+		if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LAST_EQ,
+				!(srh->first_segment == srhinfo->last_entry)))
+			return false;
+
+	if (srhinfo->mt_flags & IP6T_SRH_LAST_GT)
+		if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LAST_GT,
+				!(srh->first_segment > srhinfo->last_entry)))
+			return false;
+
+	if (srhinfo->mt_flags & IP6T_SRH_LAST_LT)
+		if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LAST_LT,
+				!(srh->first_segment < srhinfo->last_entry)))
+			return false;
+
+	/**
+	 * Tag matchig
+	 * Tag field was introduced in revision 6 of the SRH draft.
+	 */
+	if (srhinfo->mt_flags & IP6T_SRH_TAG)
+		if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_TAG,
+				!(srh->tag == srhinfo->tag)))
+			return false;
+	return true;
+}
+
+static int srh_mt6_check(const struct xt_mtchk_param *par)
+{
+	const struct ip6t_srh *srhinfo = par->matchinfo;
+
+	if (srhinfo->mt_flags & ~IP6T_SRH_MASK) {
+		pr_debug("unknown srh match flags  %X\n", srhinfo->mt_flags);

Better call pr_err() here. I know we don't do this in other
extensions, but we should not use pr_debug() for this. ip6tables
explicit refers to 'dmesg' when -EINVAL is returned.

Thanks.