[PATCH iproute2 v2] GRE over IPv6 tunnel support

[Dmitry Kozlov <xeb@mail.ru>]

GRE over IPv6 tunnel support.

Signed-off-by: Dmitry Kozlov <xeb@mail.ru>
---
Changes:
Implemented 'ip link' family of commands to manage
ip6gre/ip6gretap tunnels.

 include/linux/if_arp.h     |   15 ++
 include/linux/if_tunnel.h  |   21 +++
 include/linux/ip6_tunnel.h |   18 ++
 ip/Makefile                |    2 +-
 ip/ip6tunnel.c             |  133 +++++++++++++--
 ip/link_gre6.c             |  397 ++++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 567 insertions(+), 19 deletions(-)
 
diff --git a/include/linux/if_arp.h b/include/linux/if_arp.h
index d2de0f9..9adcc29 100644
--- a/include/linux/if_arp.h
+++ b/include/linux/if_arp.h
@@ -92,6 +92,7 @@
 #define ARPHRD_PHONET	820		/* PhoNet media type		*/
 #define ARPHRD_PHONET_PIPE 821		/* PhoNet pipe header		*/
 #define ARPHRD_CAIF	822		/* CAIF media type		*/
+#define ARPHRD_IP6GRE	823		/* GRE over IPv6		*/
 
 #define ARPHRD_VOID	  0xFFFF	/* Void type, nothing is known */
 #define ARPHRD_NONE	  0xFFFE	/* zero header length */
@@ -154,5 +155,19 @@ struct arphdr {
 
 };
 
+#ifdef __KERNEL__
+#include <linux/skbuff.h>
+
+static inline struct arphdr *arp_hdr(const struct sk_buff *skb)
+{
+	return (struct arphdr *)skb_network_header(skb);
+}
+
+static inline int arp_hdr_len(struct net_device *dev)
+{
+	/* ARP header, plus 2 device addresses, plus 2 IP addresses. */
+	return sizeof(struct arphdr) + (dev->addr_len + sizeof(u32)) * 2;
+}
+#endif
 
 #endif	/* _LINUX_IF_ARP_H */
diff --git a/include/linux/if_tunnel.h b/include/linux/if_tunnel.h
index 8c819b8..8c5035a 100644
--- a/include/linux/if_tunnel.h
+++ b/include/linux/if_tunnel.h
@@ -4,6 +4,10 @@
 #include <linux/types.h>
 #include <asm/byteorder.h>
 
+#ifdef __KERNEL__
+#include <linux/ip.h>
+#include <linux/in6.h>
+#endif
 
 #define SIOCGETTUNNEL   (SIOCDEVPRIVATE + 0)
 #define SIOCADDTUNNEL   (SIOCDEVPRIVATE + 1)
@@ -71,9 +75,26 @@ enum {
 	IFLA_GRE_TTL,
 	IFLA_GRE_TOS,
 	IFLA_GRE_PMTUDISC,
+	IFLA_GRE_ENCAP_LIMIT,
+	IFLA_GRE_FLOWINFO,
+	IFLA_GRE_FLAGS,
 	__IFLA_GRE_MAX,
 };
 
 #define IFLA_GRE_MAX	(__IFLA_GRE_MAX - 1)
 
+/* VTI-mode i_flags */
+#define VTI_ISVTI 0x0001
+
+enum {
+	IFLA_VTI_UNSPEC,
+	IFLA_VTI_LINK,
+	IFLA_VTI_IKEY,
+	IFLA_VTI_OKEY,
+	IFLA_VTI_LOCAL,
+	IFLA_VTI_REMOTE,
+	__IFLA_VTI_MAX,
+};
+
+#define IFLA_VTI_MAX	(__IFLA_VTI_MAX - 1)
 #endif /* _IF_TUNNEL_H_ */
diff --git a/include/linux/ip6_tunnel.h b/include/linux/ip6_tunnel.h
index bf22b03..1efe2e0 100644
--- a/include/linux/ip6_tunnel.h
+++ b/include/linux/ip6_tunnel.h
@@ -31,4 +31,22 @@ struct ip6_tnl_parm {
 	struct in6_addr raddr;	/* remote tunnel end-point address */
 };
 
+struct ip6_tnl_parm2 {
+	char name[IFNAMSIZ];	/* name of tunnel device */
+	int link;		/* ifindex of underlying L2 interface */
+	__u8 proto;		/* tunnel protocol */
+	__u8 encap_limit;	/* encapsulation limit for tunnel */
+	__u8 hop_limit;		/* hop limit for tunnel */
+	__be32 flowinfo;	/* traffic class and flowlabel for tunnel */
+	__u32 flags;		/* tunnel flags */
+	struct in6_addr laddr;	/* local tunnel end-point address */
+	struct in6_addr raddr;	/* remote tunnel end-point address */
+
+	__be16			i_flags;
+	__be16			o_flags;
+	__be32			i_key;
+	__be32			o_key;
+};
+
+
 #endif
diff --git a/ip/Makefile b/ip/Makefile
index e029ea1..9c54a0b 100644
--- a/ip/Makefile
+++ b/ip/Makefile
@@ -3,7 +3,7 @@ IPOBJ=ip.o ipaddress.o ipaddrlabel.o iproute.o iprule.o ipnetns.o \
     ipmaddr.o ipmonitor.o ipmroute.o ipprefix.o iptuntap.o \
     ipxfrm.o xfrm_state.o xfrm_policy.o xfrm_monitor.o \
     iplink_vlan.o link_veth.o link_gre.o iplink_can.o \
-    iplink_macvlan.o iplink_macvtap.o ipl2tp.o
+    iplink_macvlan.o iplink_macvtap.o ipl2tp.o link_gre6.o
 
 RTMONOBJ=rtmon.o
 
diff --git a/ip/ip6tunnel.c b/ip/ip6tunnel.c
index c9720eb..399a579 100644
--- a/ip/ip6tunnel.c
+++ b/ip/ip6tunnel.c
@@ -48,11 +48,12 @@ static void usage(void) __attribute__((noreturn));
 static void usage(void)
 {
 	fprintf(stderr, "Usage: ip -f inet6 tunnel { add | change | del | show } [ NAME ]\n");
-	fprintf(stderr, "          [ mode { ip6ip6 | ipip6 | any } ]\n");
+	fprintf(stderr, "          [ mode { ip6ip6 | ipip6 | ip6gre | any } ]\n");
 	fprintf(stderr, "          [ remote ADDR local ADDR ] [ dev PHYS_DEV ]\n");
 	fprintf(stderr, "          [ encaplimit ELIM ]\n");
 	fprintf(stderr ,"          [ hoplimit TTL ] [ tclass TCLASS ] [ flowlabel FLOWLABEL ]\n");
 	fprintf(stderr, "          [ dscp inherit ]\n");
+	fprintf(stderr, "          [ [i|o]seq ] [ [i|o]key KEY ] [ [i|o]csum ]\n");
 	fprintf(stderr, "\n");
 	fprintf(stderr, "Where: NAME      := STRING\n");
 	fprintf(stderr, "       ADDR      := IPV6_ADDRESS\n");
@@ -60,12 +61,13 @@ static void usage(void)
 		IPV6_DEFAULT_TNL_ENCAP_LIMIT);
 	fprintf(stderr, "       TTL       := 0..255 (default=%d)\n",
 		DEFAULT_TNL_HOP_LIMIT);
-	fprintf(stderr, "       TOS       := { 0x0..0xff | inherit }\n");
+	fprintf(stderr, "       TCLASS    := { 0x0..0xff | inherit }\n");
 	fprintf(stderr, "       FLOWLABEL := { 0x0..0xfffff | inherit }\n");
+	fprintf(stderr, "       KEY       := { DOTTED_QUAD | NUMBER }\n");
 	exit(-1);
 }
 
-static void print_tunnel(struct ip6_tnl_parm *p)
+static void print_tunnel(struct ip6_tnl_parm2 *p)
 {
 	char remote[64];
 	char local[64];
@@ -104,9 +106,29 @@ static void print_tunnel(struct ip6_tnl_parm *p)
 
 	if (p->flags & IP6_TNL_F_RCV_DSCP_COPY)
 		printf(" dscp inherit");
+	
+	if (p->proto == IPPROTO_GRE) {
+		if ((p->i_flags&GRE_KEY) && (p->o_flags&GRE_KEY) && p->o_key == p->i_key)
+			printf(" key %u", ntohl(p->i_key));
+		else if ((p->i_flags|p->o_flags)&GRE_KEY) {
+			if (p->i_flags&GRE_KEY)
+				printf(" ikey %u ", ntohl(p->i_key));
+			if (p->o_flags&GRE_KEY)
+				printf(" okey %u ", ntohl(p->o_key));
+		}
+
+		if (p->i_flags&GRE_SEQ)
+			printf("%s  Drop packets out of sequence.\n", _SL_);
+		if (p->i_flags&GRE_CSUM)
+			printf("%s  Checksum in received packet is required.", _SL_);
+		if (p->o_flags&GRE_SEQ)
+			printf("%s  Sequence packets on output.", _SL_);
+		if (p->o_flags&GRE_CSUM)
+			printf("%s  Checksum output packets.", _SL_);
+	}
 }
 
-static int parse_args(int argc, char **argv, int cmd, struct ip6_tnl_parm *p)
+static int parse_args(int argc, char **argv, int cmd, struct ip6_tnl_parm2 *p)
 {
 	int count = 0;
 	char medium[IFNAMSIZ];
@@ -124,6 +146,9 @@ static int parse_args(int argc, char **argv, int cmd, struct ip6_tnl_parm *p)
 				 strcmp(*argv, "ipip6") == 0 ||
 				 strcmp(*argv, "ip4ip6") == 0)
 				p->proto = IPPROTO_IPIP;
+			else if (strcmp(*argv, "ip6gre") == 0 ||
+				 strcmp(*argv, "gre/ipv6") == 0)
+				p->proto = IPPROTO_GRE;
 			else if (strcmp(*argv, "any/ipv6") == 0 ||
 				 strcmp(*argv, "any") == 0)
 				p->proto = 0;
@@ -199,6 +224,60 @@ static int parse_args(int argc, char **argv, int cmd, struct ip6_tnl_parm *p)
 			if (strcmp(*argv, "inherit") != 0)
 				invarg("not inherit", *argv);
 			p->flags |= IP6_TNL_F_RCV_DSCP_COPY;
+		} else if (strcmp(*argv, "key") == 0) {
+			unsigned uval;
+			NEXT_ARG();
+			p->i_flags |= GRE_KEY;
+			p->o_flags |= GRE_KEY;
+			if (strchr(*argv, '.'))
+				p->i_key = p->o_key = get_addr32(*argv);
+			else {
+				if (get_unsigned(&uval, *argv, 0)<0) {
+					fprintf(stderr, "invalid value of \"key\"\n");
+					exit(-1);
+				}
+				p->i_key = p->o_key = htonl(uval);
+			}
+		} else if (strcmp(*argv, "ikey") == 0) {
+			unsigned uval;
+			NEXT_ARG();
+			p->i_flags |= GRE_KEY;
+			if (strchr(*argv, '.'))
+				p->i_key = get_addr32(*argv);
+			else {
+				if (get_unsigned(&uval, *argv, 0)<0) {
+					fprintf(stderr, "invalid value of \"ikey\"\n");
+					exit(-1);
+				}
+				p->i_key = htonl(uval);
+			}
+		} else if (strcmp(*argv, "okey") == 0) {
+			unsigned uval;
+			NEXT_ARG();
+			p->o_flags |= GRE_KEY;
+			if (strchr(*argv, '.'))
+				p->o_key = get_addr32(*argv);
+			else {
+				if (get_unsigned(&uval, *argv, 0)<0) {
+					fprintf(stderr, "invalid value of \"okey\"\n");
+					exit(-1);
+				}
+				p->o_key = htonl(uval);
+			}
+		} else if (strcmp(*argv, "seq") == 0) {
+			p->i_flags |= GRE_SEQ;
+			p->o_flags |= GRE_SEQ;
+		} else if (strcmp(*argv, "iseq") == 0) {
+			p->i_flags |= GRE_SEQ;
+		} else if (strcmp(*argv, "oseq") == 0) {
+			p->o_flags |= GRE_SEQ;
+		} else if (strcmp(*argv, "csum") == 0) {
+			p->i_flags |= GRE_CSUM;
+			p->o_flags |= GRE_CSUM;
+		} else if (strcmp(*argv, "icsum") == 0) {
+			p->i_flags |= GRE_CSUM;
+		} else if (strcmp(*argv, "ocsum") == 0) {
+			p->o_flags |= GRE_CSUM;
 		} else {
 			if (strcmp(*argv, "name") == 0) {
 				NEXT_ARG();
@@ -209,7 +288,7 @@ static int parse_args(int argc, char **argv, int cmd, struct ip6_tnl_parm *p)
 				duparg2("name", *argv);
 			strncpy(p->name, *argv, IFNAMSIZ - 1);
 			if (cmd == SIOCCHGTUNNEL && count == 0) {
-				struct ip6_tnl_parm old_p;
+				struct ip6_tnl_parm2 old_p;
 				memset(&old_p, 0, sizeof(old_p));
 				if (tnl_get_ioctl(*argv, &old_p))
 					return -1;
@@ -227,7 +306,7 @@ static int parse_args(int argc, char **argv, int cmd, struct ip6_tnl_parm *p)
 	return 0;
 }
 
-static void ip6_tnl_parm_init(struct ip6_tnl_parm *p, int apply_default)
+static void ip6_tnl_parm_init(struct ip6_tnl_parm2 *p, int apply_default)
 {
 	memset(p, 0, sizeof(*p));
 	p->proto = IPPROTO_IPV6;
@@ -241,8 +320,8 @@ static void ip6_tnl_parm_init(struct ip6_tnl_parm *p, int apply_default)
  * @p1: user specified parameter
  * @p2: database entry
  */
-static int ip6_tnl_parm_match(const struct ip6_tnl_parm *p1,
-			      const struct ip6_tnl_parm *p2)
+static int ip6_tnl_parm_match(const struct ip6_tnl_parm2 *p1,
+			      const struct ip6_tnl_parm2 *p2)
 {
 	return ((!p1->link || p1->link == p2->link) &&
 		(!p1->name[0] || strcmp(p1->name, p2->name) == 0) &&
@@ -260,7 +339,7 @@ static int ip6_tnl_parm_match(const struct ip6_tnl_parm *p1,
 		(!p1->flags || (p1->flags & p2->flags)));
 }
 
-static int do_tunnels_list(struct ip6_tnl_parm *p)
+static int do_tunnels_list(struct ip6_tnl_parm2 *p)
 {
 	char buf[512];
 	int err = -1;
@@ -284,7 +363,7 @@ static int do_tunnels_list(struct ip6_tnl_parm *p)
 			rx_fifo, rx_frame,
 			tx_bytes, tx_packets, tx_errs, tx_drops,
 			tx_fifo, tx_colls, tx_carrier, rx_multi;
-		struct ip6_tnl_parm p1;
+		struct ip6_tnl_parm2 p1;
 		char *ptr;
 
 		buf[sizeof(buf) - 1] = '\0';
@@ -309,10 +388,12 @@ static int do_tunnels_list(struct ip6_tnl_parm *p)
 			fprintf(stderr, "Failed to get type of [%s]\n", name);
 			continue;
 		}
-		if (type != ARPHRD_TUNNEL6)
+		if (type != ARPHRD_TUNNEL6 && type != ARPHRD_IP6GRE)
 			continue;
 		memset(&p1, 0, sizeof(p1));
 		ip6_tnl_parm_init(&p1, 0);
+		if (type == ARPHRD_IP6GRE)
+			p1.proto = IPPROTO_GRE;
 		strcpy(p1.name, name);
 		p1.link = ll_name_to_index(p1.name);
 		if (p1.link == 0)
@@ -343,7 +424,7 @@ static int do_tunnels_list(struct ip6_tnl_parm *p)
 
 static int do_show(int argc, char **argv)
 {
-        struct ip6_tnl_parm p;
+        struct ip6_tnl_parm2 p;
 
 	ll_init_map(&rth);
 	ip6_tnl_parm_init(&p, 0);
@@ -366,28 +447,44 @@ static int do_show(int argc, char **argv)
 
 static int do_add(int cmd, int argc, char **argv)
 {
-	struct ip6_tnl_parm p;
+	struct ip6_tnl_parm2 p;
 
 	ip6_tnl_parm_init(&p, 1);
 
 	if (parse_args(argc, argv, cmd, &p) < 0)
 		return -1;
 
-	return tnl_add_ioctl(cmd,
-			     cmd == SIOCCHGTUNNEL && p.name[0] ?
-			     p.name : "ip6tnl0", p.name, &p);
+	switch (p.proto) {
+	case IPPROTO_IPIP:
+	case IPPROTO_IPV6:
+		return tnl_add_ioctl(cmd, "ip6tnl0", p.name, &p);
+	case IPPROTO_GRE:
+		return tnl_add_ioctl(cmd, "ip6gre0", p.name, &p);
+	default:
+		fprintf(stderr, "cannot determine tunnel mode (ip6ip6, ipip6 or gre)\n");
+	}
+	return -1;
 }
 
 static int do_del(int argc, char **argv)
 {
-	struct ip6_tnl_parm p;
+	struct ip6_tnl_parm2 p;
 
 	ip6_tnl_parm_init(&p, 1);
 
 	if (parse_args(argc, argv, SIOCDELTUNNEL, &p) < 0)
 		return -1;
 
-	return tnl_del_ioctl(p.name[0] ? p.name : "ip6tnl0", p.name, &p);
+	switch (p.proto) {
+	case IPPROTO_IPIP:
+	case IPPROTO_IPV6:
+		return tnl_del_ioctl("ip6tnl0", p.name, &p);
+	case IPPROTO_GRE:
+		return tnl_del_ioctl("ip6gre0", p.name, &p);
+	default:
+		return tnl_del_ioctl(p.name, p.name, &p);
+	}
+	return -1;
 }
 
 int do_ip6tunnel(int argc, char **argv)
diff --git a/ip/link_gre6.c b/ip/link_gre6.c
new file mode 100644
index 0000000..3ffd3ce
--- /dev/null
+++ b/ip/link_gre6.c
@@ -0,0 +1,397 @@
+/*
+ * link_gre.c	gre driver module
+ *
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ *
+ * Authors:	Herbert Xu <herbert@gondor.apana.org.au>
+ *
+ */
+
+#include <string.h>
+#include <net/if.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+
+#include <linux/ip.h>
+#include <linux/if_tunnel.h>
+#include <linux/ip6_tunnel.h>
+
+#include "rt_names.h"
+#include "utils.h"
+#include "ip_common.h"
+#include "tunnel.h"
+
+#define IP6_FLOWINFO_TCLASS	htonl(0x0FF00000)
+#define IP6_FLOWINFO_FLOWLABEL	htonl(0x000FFFFF)
+
+#define DEFAULT_TNL_HOP_LIMIT	(64)
+
+static void usage(void) __attribute__((noreturn));
+static void usage(void)
+{
+	fprintf(stderr, "Usage: ip link { add | set | change | replace | del } NAME\n");
+	fprintf(stderr, "          type { ip6gre | ip6gretap } [ remote ADDR ] [ local ADDR ]\n");
+	fprintf(stderr, "          [ [i|o]seq ] [ [i|o]key KEY ] [ [i|o]csum ]\n");
+	fprintf(stderr, "          [ hoplimit TTL ] [ encaplimit ELIM ]\n");
+	fprintf(stderr, "          [ tclass TCLASS ] [ flowlabel FLOWLABEL ]\n");
+	fprintf(stderr, "          [ dscp inherit ] [ dev PHYS_DEV ]\n");
+	fprintf(stderr, "\n");
+	fprintf(stderr, "Where: NAME      := STRING\n");
+	fprintf(stderr, "       ADDR      := IPV6_ADDRESS\n");
+	fprintf(stderr, "       TTL       := { 0..255 } (default=%d)\n",
+		DEFAULT_TNL_HOP_LIMIT);
+	fprintf(stderr, "       KEY       := { DOTTED_QUAD | NUMBER }\n");
+	fprintf(stderr, "       ELIM      := { none | 0..255 }(default=%d)\n",
+		IPV6_DEFAULT_TNL_ENCAP_LIMIT);
+	fprintf(stderr, "       FLOWLABEL := { 0x0..0xfffff | inherit }\n");
+	exit(-1);
+}
+
+static int gre_parse_opt(struct link_util *lu, int argc, char **argv,
+			 struct nlmsghdr *n)
+{
+	struct {
+		struct nlmsghdr n;
+		struct ifinfomsg i;
+		char buf[1024];
+	} req;
+	struct ifinfomsg *ifi = (struct ifinfomsg *)(n + 1);
+	struct rtattr *tb[IFLA_MAX + 1];
+	struct rtattr *linkinfo[IFLA_INFO_MAX+1];
+	struct rtattr *greinfo[IFLA_GRE_MAX + 1];
+	__u16 iflags = 0;
+	__u16 oflags = 0;
+	unsigned ikey = 0;
+	unsigned okey = 0;
+	struct in6_addr raddr = IN6ADDR_ANY_INIT;
+	struct in6_addr laddr = IN6ADDR_ANY_INIT;
+	unsigned link = 0;
+	unsigned flowinfo = 0;
+	unsigned flags = 0;
+	__u8 hop_limit = DEFAULT_TNL_HOP_LIMIT;
+	__u8 encap_limit = IPV6_DEFAULT_TNL_ENCAP_LIMIT;
+	int len;
+
+	if (!(n->nlmsg_flags & NLM_F_CREATE)) {
+		memset(&req, 0, sizeof(req));
+
+		req.n.nlmsg_len = NLMSG_LENGTH(sizeof(*ifi));
+		req.n.nlmsg_flags = NLM_F_REQUEST;
+		req.n.nlmsg_type = RTM_GETLINK;
+		req.i.ifi_family = preferred_family;
+		req.i.ifi_index = ifi->ifi_index;
+
+		if (rtnl_talk(&rth, &req.n, 0, 0, &req.n) < 0) {
+get_failed:
+			fprintf(stderr,
+				"Failed to get existing tunnel info.\n");
+			return -1;
+		}
+
+		len = req.n.nlmsg_len;
+		len -= NLMSG_LENGTH(sizeof(*ifi));
+		if (len < 0)
+			goto get_failed;
+
+		parse_rtattr(tb, IFLA_MAX, IFLA_RTA(&req.i), len);
+
+		if (!tb[IFLA_LINKINFO])
+			goto get_failed;
+
+		parse_rtattr_nested(linkinfo, IFLA_INFO_MAX, tb[IFLA_LINKINFO]);
+
+		if (!linkinfo[IFLA_INFO_DATA])
+			goto get_failed;
+
+		parse_rtattr_nested(greinfo, IFLA_GRE_MAX,
+				    linkinfo[IFLA_INFO_DATA]);
+
+		if (greinfo[IFLA_GRE_IKEY])
+			ikey = rta_getattr_u32(greinfo[IFLA_GRE_IKEY]);
+
+		if (greinfo[IFLA_GRE_OKEY])
+			okey = rta_getattr_u32(greinfo[IFLA_GRE_OKEY]);
+
+		if (greinfo[IFLA_GRE_IFLAGS])
+			iflags = rta_getattr_u16(greinfo[IFLA_GRE_IFLAGS]);
+
+		if (greinfo[IFLA_GRE_OFLAGS])
+			oflags = rta_getattr_u16(greinfo[IFLA_GRE_OFLAGS]);
+
+		if (greinfo[IFLA_GRE_LOCAL])
+			memcpy(&laddr, RTA_DATA(greinfo[IFLA_GRE_LOCAL]), sizeof(laddr));
+
+		if (greinfo[IFLA_GRE_REMOTE])
+			memcpy(&raddr, RTA_DATA(greinfo[IFLA_GRE_REMOTE]), sizeof(raddr));
+
+		if (greinfo[IFLA_GRE_TTL])
+			hop_limit = rta_getattr_u8(greinfo[IFLA_GRE_TTL]);
+
+		if (greinfo[IFLA_GRE_LINK])
+			link = rta_getattr_u32(greinfo[IFLA_GRE_LINK]);
+		
+		if (greinfo[IFLA_GRE_ENCAP_LIMIT])
+			encap_limit = rta_getattr_u8(greinfo[IFLA_GRE_ENCAP_LIMIT]);
+		
+		if (greinfo[IFLA_GRE_FLOWINFO])
+			flowinfo = rta_getattr_u32(greinfo[IFLA_GRE_FLOWINFO]);
+		
+		if (greinfo[IFLA_GRE_FLAGS])
+			flags = rta_getattr_u32(greinfo[IFLA_GRE_FLAGS]);
+	}
+
+	while (argc > 0) {
+		if (!matches(*argv, "key")) {
+			unsigned uval;
+
+			NEXT_ARG();
+			iflags |= GRE_KEY;
+			oflags |= GRE_KEY;
+			if (strchr(*argv, '.'))
+				uval = get_addr32(*argv);
+			else {
+				if (get_unsigned(&uval, *argv, 0) < 0) {
+					fprintf(stderr,
+						"Invalid value for \"key\"\n");
+					exit(-1);
+				}
+				uval = htonl(uval);
+			}
+
+			ikey = okey = uval;
+		} else if (!matches(*argv, "ikey")) {
+			unsigned uval;
+
+			NEXT_ARG();
+			iflags |= GRE_KEY;
+			if (strchr(*argv, '.'))
+				uval = get_addr32(*argv);
+			else {
+				if (get_unsigned(&uval, *argv, 0)<0) {
+					fprintf(stderr, "invalid value of \"ikey\"\n");
+					exit(-1);
+				}
+				uval = htonl(uval);
+			}
+			ikey = uval;
+		} else if (!matches(*argv, "okey")) {
+			unsigned uval;
+
+			NEXT_ARG();
+			oflags |= GRE_KEY;
+			if (strchr(*argv, '.'))
+				uval = get_addr32(*argv);
+			else {
+				if (get_unsigned(&uval, *argv, 0)<0) {
+					fprintf(stderr, "invalid value of \"okey\"\n");
+					exit(-1);
+				}
+				uval = htonl(uval);
+			}
+			okey = uval;
+		} else if (!matches(*argv, "seq")) {
+			iflags |= GRE_SEQ;
+			oflags |= GRE_SEQ;
+		} else if (!matches(*argv, "iseq")) {
+			iflags |= GRE_SEQ;
+		} else if (!matches(*argv, "oseq")) {
+			oflags |= GRE_SEQ;
+		} else if (!matches(*argv, "csum")) {
+			iflags |= GRE_CSUM;
+			oflags |= GRE_CSUM;
+		} else if (!matches(*argv, "icsum")) {
+			iflags |= GRE_CSUM;
+		} else if (!matches(*argv, "ocsum")) {
+			oflags |= GRE_CSUM;
+		} else if (!matches(*argv, "remote")) {
+			inet_prefix addr;
+			NEXT_ARG();
+			get_prefix(&addr, *argv, preferred_family);
+			if (addr.family == AF_UNSPEC)
+				invarg("\"remote\" address family is AF_UNSPEC", *argv);
+			memcpy(&raddr, &addr.data, sizeof(raddr));
+		} else if (!matches(*argv, "local")) {
+			inet_prefix addr;
+			NEXT_ARG();
+			get_prefix(&addr, *argv, preferred_family);
+			if (addr.family == AF_UNSPEC)
+				invarg("\"local\" address family is AF_UNSPEC", *argv);
+			memcpy(&laddr, &addr.data, sizeof(laddr));
+		} else if (!matches(*argv, "dev")) {
+			NEXT_ARG();
+			link = if_nametoindex(*argv);
+			if (link == 0)
+				exit(-1);
+		} else if (!matches(*argv, "ttl") ||
+			   !matches(*argv, "hoplimit")) {
+			__u8 uval;
+			NEXT_ARG();
+			if (get_u8(&uval, *argv, 0))
+				invarg("invalid TTL", *argv);
+			hop_limit = uval;
+		} else if (!matches(*argv, "tos") ||
+			   !matches(*argv, "tclass") ||
+			   !matches(*argv, "dsfield")) {
+			__u8 uval;
+			NEXT_ARG();
+			if (strcmp(*argv, "inherit") == 0)
+				flags |= IP6_TNL_F_USE_ORIG_TCLASS;
+			else {
+				if (get_u8(&uval, *argv, 16))
+					invarg("invalid TClass", *argv);
+				flowinfo |= htonl((__u32)uval << 20) & IP6_FLOWINFO_TCLASS;
+				flags &= ~IP6_TNL_F_USE_ORIG_TCLASS;
+			}
+		} else if (strcmp(*argv, "flowlabel") == 0 ||
+			   strcmp(*argv, "fl") == 0) {
+			__u32 uval;
+			NEXT_ARG();
+			if (strcmp(*argv, "inherit") == 0)
+				flags |= IP6_TNL_F_USE_ORIG_FLOWLABEL;
+			else {
+				if (get_u32(&uval, *argv, 16))
+					invarg("invalid Flowlabel", *argv);
+				if (uval > 0xFFFFF)
+					invarg("invalid Flowlabel", *argv);
+				flowinfo |= htonl(uval) & IP6_FLOWINFO_FLOWLABEL;
+				flags &= ~IP6_TNL_F_USE_ORIG_FLOWLABEL;
+			}
+		} else if (strcmp(*argv, "dscp") == 0) {
+			NEXT_ARG();
+			if (strcmp(*argv, "inherit") != 0)
+				invarg("not inherit", *argv);
+			flags |= IP6_TNL_F_RCV_DSCP_COPY;
+		} else 
+			usage();
+		argc--; argv++;
+	}
+
+	addattr32(n, 1024, IFLA_GRE_IKEY, ikey);
+	addattr32(n, 1024, IFLA_GRE_OKEY, okey);
+	addattr_l(n, 1024, IFLA_GRE_IFLAGS, &iflags, 2);
+	addattr_l(n, 1024, IFLA_GRE_OFLAGS, &oflags, 2);
+	addattr_l(n, 1024, IFLA_GRE_LOCAL, &laddr, sizeof(laddr));
+	addattr_l(n, 1024, IFLA_GRE_REMOTE, &raddr, sizeof(raddr));
+	if (link)
+		addattr32(n, 1024, IFLA_GRE_LINK, link);
+	addattr_l(n, 1024, IFLA_GRE_TTL, &hop_limit, 1);
+	addattr_l(n, 1024, IFLA_GRE_ENCAP_LIMIT, &encap_limit, 1);
+	addattr_l(n, 1024, IFLA_GRE_FLOWINFO, &flowinfo, 4);
+	addattr_l(n, 1024, IFLA_GRE_FLAGS, &flowinfo, 4);
+
+	return 0;
+}
+
+static void gre_print_opt(struct link_util *lu, FILE *f, struct rtattr *tb[])
+{
+	char s1[1024];
+	char s2[64];
+	const char *local = "any";
+	const char *remote = "any";
+	unsigned iflags = 0;
+	unsigned oflags = 0;
+	unsigned flags = 0;
+	unsigned flowinfo = 0;
+	struct in6_addr in6_addr_any = IN6ADDR_ANY_INIT;
+
+	if (!tb)
+		return;
+
+	if (tb[IFLA_GRE_FLAGS])
+		flags = rta_getattr_u32(tb[IFLA_GRE_FLAGS]);
+	
+	if (tb[IFLA_GRE_FLOWINFO])
+		flags = rta_getattr_u32(tb[IFLA_GRE_FLOWINFO]);
+
+	if (tb[IFLA_GRE_REMOTE]) {
+		struct in6_addr addr;
+		memcpy(&addr, RTA_DATA(tb[IFLA_GRE_REMOTE]), sizeof(addr));
+
+		if (memcmp(&addr, &in6_addr_any, sizeof(addr)))
+			remote = format_host(AF_INET6, sizeof(addr), &addr, s1, sizeof(s1));
+	}
+
+	fprintf(f, "remote %s ", remote);
+
+	if (tb[IFLA_GRE_LOCAL]) {
+		struct in6_addr addr;
+		memcpy(&addr, RTA_DATA(tb[IFLA_GRE_LOCAL]), sizeof(addr));
+
+		if (memcmp(&addr, &in6_addr_any, sizeof(addr)))
+			local = format_host(AF_INET6, sizeof(addr), &addr, s1, sizeof(s1));
+	}
+
+	fprintf(f, "local %s ", local);
+
+	if (tb[IFLA_GRE_LINK] && rta_getattr_u32(tb[IFLA_GRE_LINK])) {
+		unsigned link = rta_getattr_u32(tb[IFLA_GRE_LINK]);
+		const char *n = if_indextoname(link, s2);
+
+		if (n)
+			fprintf(f, "dev %s ", n);
+		else
+			fprintf(f, "dev %u ", link);
+	}
+
+	if (tb[IFLA_GRE_TTL] && rta_getattr_u8(tb[IFLA_GRE_TTL]))
+		fprintf(f, "hoplimit %d ", rta_getattr_u8(tb[IFLA_GRE_TTL]));
+
+	if (flags & IP6_TNL_F_IGN_ENCAP_LIMIT)
+		fprintf(f, "encaplimit none ");
+	else if (tb[IFLA_GRE_ENCAP_LIMIT]) {
+		int encap_limit = rta_getattr_u8(tb[IFLA_GRE_ENCAP_LIMIT]);
+
+		fprintf(f, "encaplimit %d ", encap_limit);
+	}
+	
+	if (flags & IP6_TNL_F_USE_ORIG_FLOWLABEL)
+		fprintf(f, "flowlabel inherit ");
+	else
+		fprintf(f, "flowlabel 0x%05x ", ntohl(flowinfo & IP6_FLOWINFO_FLOWLABEL));
+	
+	if (flags & IP6_TNL_F_RCV_DSCP_COPY)
+		fprintf(f, "dscp inherit ");
+
+	if (tb[IFLA_GRE_IFLAGS])
+		iflags = rta_getattr_u16(tb[IFLA_GRE_IFLAGS]);
+
+	if (tb[IFLA_GRE_OFLAGS])
+		oflags = rta_getattr_u16(tb[IFLA_GRE_OFLAGS]);
+
+	if ((iflags & GRE_KEY) && tb[IFLA_GRE_IKEY]) {
+		inet_ntop(AF_INET, RTA_DATA(tb[IFLA_GRE_IKEY]), s2, sizeof(s2));
+		fprintf(f, "ikey %s ", s2);
+	}
+
+	if ((oflags & GRE_KEY) && tb[IFLA_GRE_OKEY]) {
+		inet_ntop(AF_INET, RTA_DATA(tb[IFLA_GRE_OKEY]), s2, sizeof(s2));
+		fprintf(f, "okey %s ", s2);
+	}
+
+	if (iflags & GRE_SEQ)
+		fputs("iseq ", f);
+	if (oflags & GRE_SEQ)
+		fputs("oseq ", f);
+	if (iflags & GRE_CSUM)
+		fputs("icsum ", f);
+	if (oflags & GRE_CSUM)
+		fputs("ocsum ", f);
+}
+
+struct link_util ip6gre_link_util = {
+	.id = "ip6gre",
+	.maxattr = IFLA_GRE_MAX,
+	.parse_opt = gre_parse_opt,
+	.print_opt = gre_print_opt,
+};
+
+struct link_util ip6gretap_link_util = {
+	.id = "ip6gretap",
+	.maxattr = IFLA_GRE_MAX,
+	.parse_opt = gre_parse_opt,
+	.print_opt = gre_print_opt,
+};