Message-Id: <20200624192310.16923-4-justin.iurman@uliege.be>
Date:   Wed, 24 Jun 2020 21:23:08 +0200
From:   Justin Iurman <justin.iurman@...ege.be>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, justin.iurman@...ege.be
Subject: [PATCH net-next 3/5] ipv6: ioam: Data plane support for Pre-allocated Trace

Implement support for processing the IOAM Pre-allocated Trace with IPv6,
see [1] and [2]. Introduce a new IPv6 Hop-by-Hop TLV option
IPV6_TLV_IOAM_HOPOPTS, see IANA [3].

A per-interface sysctl ioam6_enabled is provided to accept/drop IOAM
packets. Default is drop.

Another per-interface sysctl ioam6_id is provided to define the IOAM
(unique) identifier of the interface.

A per-namespace sysctl ioam6_id is provided to define the IOAM (unique)
identifier of the node.

Two relativistic hash tables: one for IOAM namespaces, the other for
IOAM schemas. A namespace can only have a single active schema and a
schema can only be attached to a single namespace (1:1 relationship).

  [1] https://tools.ietf.org/html/draft-ietf-ippm-ioam-ipv6-options-01
  [2] https://tools.ietf.org/html/draft-ietf-ippm-ioam-data-09
  [3] https://www.iana.org/assignments/ipv6-parameters/ipv6-parameters.xhtml#ipv6-parameters-2

Signed-off-by: Justin Iurman <justin.iurman@...ege.be>
---
 include/linux/ipv6.h       |   2 +
 include/net/ioam6.h        |  98 +++++++++++
 include/net/netns/ipv6.h   |   2 +
 include/uapi/linux/in6.h   |   1 +
 include/uapi/linux/ipv6.h  |   2 +
 net/ipv6/Makefile          |   2 +-
 net/ipv6/addrconf.c        |  20 +++
 net/ipv6/af_inet6.c        |   7 +
 net/ipv6/exthdrs.c         |  67 ++++++++
 net/ipv6/ioam6.c           | 326 +++++++++++++++++++++++++++++++++++++
 net/ipv6/sysctl_net_ipv6.c |   7 +
 11 files changed, 533 insertions(+), 1 deletion(-)
 create mode 100644 include/net/ioam6.h
 create mode 100644 net/ipv6/ioam6.c

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 5312a718bc7a..15732f964c6e 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -75,6 +75,8 @@ struct ipv6_devconf {
 	__s32		disable_policy;
 	__s32           ndisc_tclass;
 	__s32		rpl_seg_enabled;
+	__u32		ioam6_enabled;
+	__u32           ioam6_id;
 
 	struct ctl_table_header *sysctl_header;
 };
diff --git a/include/net/ioam6.h b/include/net/ioam6.h
new file mode 100644
index 000000000000..2a910bc99947
--- /dev/null
+++ b/include/net/ioam6.h
@@ -0,0 +1,98 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *  IOAM IPv6 implementation
+ *
+ *  Author:
+ *  Justin Iurman <justin.iurman@...ege.be>
+ */
+
+#ifndef _NET_IOAM6_H
+#define _NET_IOAM6_H
+
+#include <linux/net.h>
+#include <linux/ipv6.h>
+#include <linux/rhashtable-types.h>
+
+#define IOAM6_OPT_TRACE_PREALLOC 0
+
+#define IOAM6_TRACE_FLAG_OVERFLOW (1 << 3)
+
+#define IOAM6_TRACE_TYPE0  (1 << 31)
+#define IOAM6_TRACE_TYPE1  (1 << 30)
+#define IOAM6_TRACE_TYPE2  (1 << 29)
+#define IOAM6_TRACE_TYPE3  (1 << 28)
+#define IOAM6_TRACE_TYPE4  (1 << 27)
+#define IOAM6_TRACE_TYPE5  (1 << 26)
+#define IOAM6_TRACE_TYPE6  (1 << 25)
+#define IOAM6_TRACE_TYPE7  (1 << 24)
+#define IOAM6_TRACE_TYPE8  (1 << 23)
+#define IOAM6_TRACE_TYPE9  (1 << 22)
+#define IOAM6_TRACE_TYPE10 (1 << 21)
+#define IOAM6_TRACE_TYPE11 (1 << 20)
+#define IOAM6_TRACE_TYPE22 (1 << 9)
+
+#define IOAM6_EMPTY_FIELD_u16 0xffff
+#define IOAM6_EMPTY_FIELD_u24 0x00ffffff
+#define IOAM6_EMPTY_FIELD_u32 0xffffffff
+#define IOAM6_EMPTY_FIELD_u56 0x00ffffffffffffff
+#define IOAM6_EMPTY_FIELD_u64 0xffffffffffffffff
+
+struct ioam6_common_hdr {
+	u8 opt_type;
+	u8 opt_len;
+	u8 res;
+	u8 ioam_type;
+	__be16 namespace_id;
+} __packed;
+
+struct ioam6_trace_hdr {
+	__be16 info;
+	__be32 type;
+} __packed;
+
+struct ioam6_namespace {
+	struct rhash_head head;
+	struct rcu_head rcu;
+
+	__be16 id;
+	__be64 data;
+	bool remove_tlv;
+
+	struct ioam6_schema *schema;
+};
+
+struct ioam6_schema {
+	struct rhash_head head;
+	struct rcu_head rcu;
+
+	u32 id;
+	int len;
+	__be32 hdr;
+	u8 *data;
+
+	struct ioam6_namespace *ns;
+};
+
+struct ioam6_pernet_data {
+	struct mutex lock;
+	struct rhashtable namespaces;
+	struct rhashtable schemas;
+};
+
+static inline struct ioam6_pernet_data *ioam6_pernet(struct net *net)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+	return net->ipv6.ioam6_data;
+#else
+	return NULL;
+#endif
+}
+
+extern struct ioam6_namespace *ioam6_namespace(struct net *net, __be16 id);
+extern void ioam6_fill_trace_data(struct sk_buff *skb, int traceoff,
+				  struct ioam6_namespace *ns);
+
+extern int ioam6_init(void);
+extern void ioam6_exit(void);
+
+#endif
diff --git a/include/net/netns/ipv6.h b/include/net/netns/ipv6.h
index 5ec054473d81..89b27fa721f4 100644
--- a/include/net/netns/ipv6.h
+++ b/include/net/netns/ipv6.h
@@ -51,6 +51,7 @@ struct netns_sysctl_ipv6 {
 	int max_hbh_opts_len;
 	int seg6_flowlabel;
 	bool skip_notify_on_dev_down;
+	unsigned int ioam6_id;
 };
 
 struct netns_ipv6 {
@@ -115,6 +116,7 @@ struct netns_ipv6 {
 		spinlock_t	lock;
 		u32		seq;
 	} ip6addrlbl_table;
+	struct ioam6_pernet_data *ioam6_data;
 };
 
 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
diff --git a/include/uapi/linux/in6.h b/include/uapi/linux/in6.h
index 9f2273a08356..1c98435220c9 100644
--- a/include/uapi/linux/in6.h
+++ b/include/uapi/linux/in6.h
@@ -145,6 +145,7 @@ struct in6_flowlabel_req {
 #define IPV6_TLV_PADN		1
 #define IPV6_TLV_ROUTERALERT	5
 #define IPV6_TLV_CALIPSO	7	/* RFC 5570 */
+#define IPV6_TLV_IOAM_HOPOPTS	49
 #define IPV6_TLV_JUMBO		194
 #define IPV6_TLV_HAO		201	/* home address option */
 
diff --git a/include/uapi/linux/ipv6.h b/include/uapi/linux/ipv6.h
index 13e8751bf24a..eb521b2dd885 100644
--- a/include/uapi/linux/ipv6.h
+++ b/include/uapi/linux/ipv6.h
@@ -189,6 +189,8 @@ enum {
 	DEVCONF_ACCEPT_RA_RT_INFO_MIN_PLEN,
 	DEVCONF_NDISC_TCLASS,
 	DEVCONF_RPL_SEG_ENABLED,
+	DEVCONF_IOAM6_ENABLED,
+	DEVCONF_IOAM6_ID,
 	DEVCONF_MAX
 };
 
diff --git a/net/ipv6/Makefile b/net/ipv6/Makefile
index cf7b47bdb9b3..b7ef10d417d6 100644
--- a/net/ipv6/Makefile
+++ b/net/ipv6/Makefile
@@ -10,7 +10,7 @@ ipv6-objs :=	af_inet6.o anycast.o ip6_output.o ip6_input.o addrconf.o \
 		route.o ip6_fib.o ipv6_sockglue.o ndisc.o udp.o udplite.o \
 		raw.o icmp.o mcast.o reassembly.o tcp_ipv6.o ping.o \
 		exthdrs.o datagram.o ip6_flowlabel.o inet6_connection_sock.o \
-		udp_offload.o seg6.o fib6_notifier.o rpl.o
+		udp_offload.o seg6.o fib6_notifier.o rpl.o ioam6.o
 
 ipv6-offload :=	ip6_offload.o tcpv6_offload.o exthdrs_offload.o
 
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 840bfdb3d7bd..6c952a28ade2 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -236,6 +236,8 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = {
 	.addr_gen_mode		= IN6_ADDR_GEN_MODE_EUI64,
 	.disable_policy		= 0,
 	.rpl_seg_enabled	= 0,
+	.ioam6_enabled		= 0,
+	.ioam6_id               = 0,
 };
 
 static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
@@ -291,6 +293,8 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
 	.addr_gen_mode		= IN6_ADDR_GEN_MODE_EUI64,
 	.disable_policy		= 0,
 	.rpl_seg_enabled	= 0,
+	.ioam6_enabled		= 0,
+	.ioam6_id               = 0,
 };
 
 /* Check if link is ready: is it up and is a valid qdisc available */
@@ -5487,6 +5491,8 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf,
 	array[DEVCONF_DISABLE_POLICY] = cnf->disable_policy;
 	array[DEVCONF_NDISC_TCLASS] = cnf->ndisc_tclass;
 	array[DEVCONF_RPL_SEG_ENABLED] = cnf->rpl_seg_enabled;
+	array[DEVCONF_IOAM6_ENABLED] = cnf->ioam6_enabled;
+	array[DEVCONF_IOAM6_ID] = cnf->ioam6_id;
 }
 
 static inline size_t inet6_ifla6_size(void)
@@ -6867,6 +6873,20 @@ static const struct ctl_table addrconf_sysctl[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
+	{
+		.procname	= "ioam6_enabled",
+		.data		= &ipv6_devconf.ioam6_enabled,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "ioam6_id",
+		.data		= &ipv6_devconf.ioam6_id,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
 	{
 		/* sentinel */
 	}
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index b304b882e031..63a9ffc4b283 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -62,6 +62,7 @@
 #include <net/rpl.h>
 #include <net/compat.h>
 #include <net/xfrm.h>
+#include <net/ioam6.h>
 
 #include <linux/uaccess.h>
 #include <linux/mroute6.h>
@@ -1187,6 +1188,10 @@ static int __init inet6_init(void)
 	if (err)
 		goto rpl_fail;
 
+	err = ioam6_init();
+	if (err)
+		goto ioam6_fail;
+
 	err = igmp6_late_init();
 	if (err)
 		goto igmp6_late_err;
@@ -1210,6 +1215,8 @@ static int __init inet6_init(void)
 #endif
 igmp6_late_err:
 	rpl_exit();
+ioam6_fail:
+	ioam6_exit();
 rpl_fail:
 	seg6_exit();
 seg6_fail:
diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index f27ab3bf2e0c..00aee1358f1c 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -49,6 +49,8 @@
 #include <net/seg6_hmac.h>
 #endif
 #include <net/rpl.h>
+#include <net/ioam6.h>
+#include <net/dst_metadata.h>
 
 #include <linux/uaccess.h>
 
@@ -1010,6 +1012,67 @@ static int ipv6_hop_ra(struct sk_buff *skb, int optoff)
 	return TLV_REJECT;
 }
 
+/* IOAM */
+
+static int ipv6_hop_ioam(struct sk_buff *skb, int optoff)
+{
+	struct ioam6_common_hdr *ioamh;
+	struct ioam6_namespace *ns;
+
+	/* Must be 4n-aligned */
+	if (optoff & 3)
+		goto drop;
+
+	if (!skb_valid_dst(skb))
+		ip6_route_input(skb);
+
+	/* IOAM must be enabled on ingress interface */
+	if (!__in6_dev_get(skb->dev)->cnf.ioam6_enabled)
+		goto drop;
+
+	ioamh = (struct ioam6_common_hdr *)(skb_network_header(skb) + optoff);
+	ns = ioam6_namespace(ipv6_skb_net(skb), ioamh->namespace_id);
+
+	/* Unknown IOAM namespace, either:
+	 *  - Drop it if IOAM is not enabled on egress interface (if any)
+	 *  - Ignore it otherwise
+	 */
+	if (!ns) {
+		if (!__in6_dev_get(skb_dst(skb)->dev)->cnf.ioam6_enabled &&
+		    !(skb_dst(skb)->dev->flags & IFF_LOOPBACK))
+			goto drop;
+
+		goto accept;
+	}
+
+	if (ns->remove_tlv && !(skb_dst(skb)->dev->flags & IFF_LOOPBACK))
+		goto remove;
+
+	/* Known IOAM namespace which must not be removed:
+	 * IOAM must be enabled on egress interface
+	 */
+	if (!__in6_dev_get(skb_dst(skb)->dev)->cnf.ioam6_enabled &&
+	    !(skb_dst(skb)->dev->flags & IFF_LOOPBACK))
+		goto drop;
+
+	switch (ioamh->ioam_type) {
+	case IOAM6_OPT_TRACE_PREALLOC:
+		ioam6_fill_trace_data(skb, optoff + sizeof(*ioamh), ns);
+		IP6CB(skb)->flags |= IP6SKB_IOAM;
+		break;
+	default:
+		break;
+	}
+
+accept:
+	return TLV_ACCEPT;
+remove:
+	return TLV_REMOVE;
+drop:
+	kfree_skb(skb);
+	return TLV_REJECT;
+}
+
 /* Jumbo payload */
 
 static int ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
@@ -1081,6 +1144,10 @@ static const struct tlvtype_proc tlvprochopopt_lst[] = {
 		.type	= IPV6_TLV_ROUTERALERT,
 		.func	= ipv6_hop_ra,
 	},
+	{
+		.type	= IPV6_TLV_IOAM_HOPOPTS,
+		.func	= ipv6_hop_ioam,
+	},
 	{
 		.type	= IPV6_TLV_JUMBO,
 		.func	= ipv6_hop_jumbo,
diff --git a/net/ipv6/ioam6.c b/net/ipv6/ioam6.c
new file mode 100644
index 000000000000..406aa78eb504
--- /dev/null
+++ b/net/ipv6/ioam6.c
@@ -0,0 +1,326 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  IOAM IPv6 implementation
+ *
+ *  Author:
+ *  Justin Iurman <justin.iurman@...ege.be>
+ */
+
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/net.h>
+#include <linux/rhashtable.h>
+
+#include <net/addrconf.h>
+#include <net/ioam6.h>
+
+static inline void ioam6_ns_release(struct ioam6_namespace *ns)
+{
+	kfree_rcu(ns, rcu);
+}
+
+static inline void ioam6_sc_release(struct ioam6_schema *sc)
+{
+	kfree_rcu(sc, rcu);
+}
+
+static void ioam6_free_ns(void *ptr, void *arg)
+{
+	struct ioam6_namespace *ns = (struct ioam6_namespace *)ptr;
+
+	if (ns)
+		ioam6_ns_release(ns);
+}
+
+static void ioam6_free_sc(void *ptr, void *arg)
+{
+	struct ioam6_schema *sc = (struct ioam6_schema *)ptr;
+
+	if (sc)
+		ioam6_sc_release(sc);
+}
+
+static int ioam6_ns_cmpfn(struct rhashtable_compare_arg *arg, const void *obj)
+{
+	const struct ioam6_namespace *ns = obj;
+
+	return (ns->id != *(__be16 *)arg->key);
+}
+
+static int ioam6_sc_cmpfn(struct rhashtable_compare_arg *arg, const void *obj)
+{
+	const struct ioam6_schema *sc = obj;
+
+	return (sc->id != *(u32 *)arg->key);
+}
+
+static const struct rhashtable_params rht_ns_params = {
+	.key_len		= sizeof(__be16),
+	.key_offset		= offsetof(struct ioam6_namespace, id),
+	.head_offset		= offsetof(struct ioam6_namespace, head),
+	.automatic_shrinking	= true,
+	.obj_cmpfn		= ioam6_ns_cmpfn,
+};
+
+static const struct rhashtable_params rht_sc_params = {
+	.key_len		= sizeof(u32),
+	.key_offset		= offsetof(struct ioam6_schema, id),
+	.head_offset		= offsetof(struct ioam6_schema, head),
+	.automatic_shrinking	= true,
+	.obj_cmpfn		= ioam6_sc_cmpfn,
+};
+
+struct ioam6_namespace *ioam6_namespace(struct net *net, __be16 id)
+{
+	struct ioam6_pernet_data *nsdata = ioam6_pernet(net);
+
+	return rhashtable_lookup_fast(&nsdata->namespaces, &id, rht_ns_params);
+}
+
+void ioam6_fill_trace_data_node(struct sk_buff *skb, int nodeoff,
+				u32 trace_type, struct ioam6_namespace *ns)
+{
+	u8 *data = skb_network_header(skb) + nodeoff;
+	struct __kernel_sock_timeval ts;
+	u64 raw_u64;
+	u32 raw_u32;
+	u16 raw_u16;
+	u8 byte;
+
+	/* hop_lim and node_id */
+	if (trace_type & IOAM6_TRACE_TYPE0) {
+		byte = ipv6_hdr(skb)->hop_limit - 1;
+		raw_u32 = dev_net(skb->dev)->ipv6.sysctl.ioam6_id;
+		if (!raw_u32)
+			raw_u32 = IOAM6_EMPTY_FIELD_u24;
+		else
+			raw_u32 &= IOAM6_EMPTY_FIELD_u24;
+		*(__be32 *)data = cpu_to_be32((byte << 24) | raw_u32);
+		data += sizeof(__be32);
+	}
+
+	/* ingress_if_id and egress_if_id */
+	if (trace_type & IOAM6_TRACE_TYPE1) {
+		raw_u16 = __in6_dev_get(skb->dev)->cnf.ioam6_id;
+		if (!raw_u16)
+			raw_u16 = IOAM6_EMPTY_FIELD_u16;
+		*(__be16 *)data = cpu_to_be16(raw_u16);
+		data += sizeof(__be16);
+
+		raw_u16 = __in6_dev_get(skb_dst(skb)->dev)->cnf.ioam6_id;
+		if (!raw_u16)
+			raw_u16 = IOAM6_EMPTY_FIELD_u16;
+		*(__be16 *)data = cpu_to_be16(raw_u16);
+		data += sizeof(__be16);
+	}
+
+	/* timestamp seconds */
+	if (trace_type & IOAM6_TRACE_TYPE2) {
+		if (!skb->tstamp) {
+			*(__be32 *)data = cpu_to_be32(IOAM6_EMPTY_FIELD_u32);
+		} else {
+			skb_get_new_timestamp(skb, &ts);
+			*(__be32 *)data = cpu_to_be32((u32)ts.tv_sec);
+		}
+		data += sizeof(__be32);
+	}
+
+	/* timestamp subseconds */
+	if (trace_type & IOAM6_TRACE_TYPE3) {
+		if (!skb->tstamp) {
+			*(__be32 *)data = cpu_to_be32(IOAM6_EMPTY_FIELD_u32);
+		} else {
+			if (!(trace_type & IOAM6_TRACE_TYPE2))
+				skb_get_new_timestamp(skb, &ts);
+			*(__be32 *)data = cpu_to_be32((u32)ts.tv_usec);
+		}
+		data += sizeof(__be32);
+	}
+
+	/* transit delay */
+	if (trace_type & IOAM6_TRACE_TYPE4) {
+		*(__be32 *)data = cpu_to_be32(IOAM6_EMPTY_FIELD_u32);
+		data += sizeof(__be32);
+	}
+
+	/* namespace data */
+	if (trace_type & IOAM6_TRACE_TYPE5) {
+		*(__be32 *)data = (__be32)ns->data;
+		data += sizeof(__be32);
+	}
+
+	/* queue depth */
+	if (trace_type & IOAM6_TRACE_TYPE6) {
+		*(__be32 *)data = cpu_to_be32(IOAM6_EMPTY_FIELD_u32);
+		data += sizeof(__be32);
+	}
+
+	/* hop_lim and node_id (wide) */
+	if (trace_type & IOAM6_TRACE_TYPE7) {
+		byte = ipv6_hdr(skb)->hop_limit - 1;
+		raw_u64 = dev_net(skb->dev)->ipv6.sysctl.ioam6_id;
+		if (!raw_u64)
+			raw_u64 = IOAM6_EMPTY_FIELD_u56;
+		else
+			raw_u64 &= IOAM6_EMPTY_FIELD_u56;
+		*(__be64 *)data = cpu_to_be64(((u64)byte << 56) | raw_u64);
+		data += sizeof(__be64);
+	}
+
+	/* ingress_if_id and egress_if_id (wide) */
+	if (trace_type & IOAM6_TRACE_TYPE8) {
+		raw_u32 = __in6_dev_get(skb->dev)->cnf.ioam6_id;
+		if (!raw_u32)
+			raw_u32 = IOAM6_EMPTY_FIELD_u32;
+		*(__be32 *)data = cpu_to_be32(raw_u32);
+		data += sizeof(__be32);
+
+		raw_u32 = __in6_dev_get(skb_dst(skb)->dev)->cnf.ioam6_id;
+		if (!raw_u32)
+			raw_u32 = IOAM6_EMPTY_FIELD_u32;
+		*(__be32 *)data = cpu_to_be32(raw_u32);
+		data += sizeof(__be32);
+	}
+
+	/* namespace data (wide) */
+	if (trace_type & IOAM6_TRACE_TYPE9) {
+		*(__be64 *)data = ns->data;
+		data += sizeof(__be64);
+	}
+
+	/* buffer occupancy */
+	if (trace_type & IOAM6_TRACE_TYPE10) {
+		*(__be32 *)data = cpu_to_be32(IOAM6_EMPTY_FIELD_u32);
+		data += sizeof(__be32);
+	}
+
+	/* checksum complement */
+	if (trace_type & IOAM6_TRACE_TYPE11) {
+		*(__be32 *)data = cpu_to_be32(IOAM6_EMPTY_FIELD_u32);
+		data += sizeof(__be32);
+	}
+
+	/* opaque state snapshot */
+	if (trace_type & IOAM6_TRACE_TYPE22) {
+		if (!ns->schema) {
+			*(__be32 *)data = cpu_to_be32(IOAM6_EMPTY_FIELD_u24);
+		} else {
+			*(__be32 *)data = ns->schema->hdr;
+			data += sizeof(__be32);
+			memcpy(data, ns->schema->data, ns->schema->len);
+		}
+	}
+}
+
+void ioam6_fill_trace_data(struct sk_buff *skb, int traceoff,
+			   struct ioam6_namespace *ns)
+{
+	u8 nodelen, flags, remlen, sclen = 0;
+	struct ioam6_trace_hdr *trh;
+	int nodeoff;
+	u16 info;
+	u32 type;
+
+	trh = (struct ioam6_trace_hdr *)(skb_network_header(skb) + traceoff);
+	info = be16_to_cpu(trh->info);
+	type = be32_to_cpu(trh->type);
+
+	nodelen = info >> 11;
+	flags = (info >> 7) & 0xf;
+	remlen = info & 0x7f;
+
+	/* Skip if Overflow bit is set OR
+	 * if an unknown type (bit 12-21) is set
+	 */
+	if ((flags & IOAM6_TRACE_FLAG_OVERFLOW) || (type & 0xffc00))
+		return;
+
+	/* NodeLen does not include Opaque State Snapshot length. We need to
+	 * take it into account if the corresponding bit is set and if current
+	 * IOAM namespace has an active schema attached to it
+	 */
+	if (type & IOAM6_TRACE_TYPE22) {
+		/* Opaque State Snapshot header size */
+		sclen = sizeof_field(struct ioam6_schema, hdr) / 4;
+
+		if (ns->schema)
+			sclen += ns->schema->len / 4;
+	}
+
+	/* Not enough space remaining: set Overflow bit and skip */
+	if (!remlen || remlen < (nodelen + sclen)) {
+		info |= IOAM6_TRACE_FLAG_OVERFLOW << 7;
+		trh->info = cpu_to_be16(info);
+		return;
+	}
+
+	nodeoff = traceoff + sizeof(*trh) + remlen*4 - nodelen*4 - sclen*4;
+	ioam6_fill_trace_data_node(skb, nodeoff, type, ns);
+
+	/* Update RemainingLen */
+	remlen -= nodelen + sclen;
+	info = (info & 0xff80) | remlen;
+	trh->info = cpu_to_be16(info);
+}
+
+static int __net_init ioam6_net_init(struct net *net)
+{
+	struct ioam6_pernet_data *nsdata;
+	int err = -ENOMEM;
+
+	nsdata = kzalloc(sizeof(*nsdata), GFP_KERNEL);
+	if (!nsdata)
+		goto out;
+
+	mutex_init(&nsdata->lock);
+	net->ipv6.ioam6_data = nsdata;
+
+	err = rhashtable_init(&nsdata->namespaces, &rht_ns_params);
+	if (err)
+		goto free_nsdata;
+
+	err = rhashtable_init(&nsdata->schemas, &rht_sc_params);
+	if (err)
+		goto free_rht_ns;
+
+out:
+	return err;
+free_rht_ns:
+	rhashtable_destroy(&nsdata->namespaces);
+free_nsdata:
+	kfree(nsdata);
+	net->ipv6.ioam6_data = NULL;
+	goto out;
+}
+
+static void __net_exit ioam6_net_exit(struct net *net)
+{
+	struct ioam6_pernet_data *nsdata = ioam6_pernet(net);
+
+	rhashtable_free_and_destroy(&nsdata->namespaces, ioam6_free_ns, NULL);
+	rhashtable_free_and_destroy(&nsdata->schemas, ioam6_free_sc, NULL);
+
+	kfree(nsdata);
+}
+
+static struct pernet_operations ioam6_net_ops = {
+	.init = ioam6_net_init,
+	.exit = ioam6_net_exit,
+};
+
+int __init ioam6_init(void)
+{
+	int err = register_pernet_subsys(&ioam6_net_ops);
+
+	if (err)
+		return err;
+
+	pr_info("In-situ OAM (IOAM) with IPv6\n");
+	return 0;
+}
+
+void ioam6_exit(void)
+{
+	unregister_pernet_subsys(&ioam6_net_ops);
+}
diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c
index fac2135aa47b..da49b33ab6fc 100644
--- a/net/ipv6/sysctl_net_ipv6.c
+++ b/net/ipv6/sysctl_net_ipv6.c
@@ -159,6 +159,13 @@ static struct ctl_table ipv6_table_template[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
+	{
+		.procname	= "ioam6_id",
+		.data		= &init_net.ipv6.sysctl.ioam6_id,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec
+	},
 	{ }
 };
 
-- 
2.17.1

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