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, see IANA [3].

A new per-interface sysctl is introduced. The value is a boolean to accept (=1)
or ignore (=0, by default) IPv6 IOAM options on ingress for an interface:
 - net.ipv6.conf.XXX.ioam6_enabled

Two other sysctls are introduced to define IOAM IDs, represented by an integer.
They are respectively per-namespace and per-interface:
 - net.ipv6.ioam6_id
 - net.ipv6.conf.XXX.ioam6_id

The value of the first one represents the IOAM ID of the node itself (u32; max
and default value = U32_MAX>>8, due to hop limit concatenation) while the other
represents the IOAM ID of an interface (u16; max and default value = U16_MAX).

Each "ioam6_id" sysctl has a "_wide" equivalent:
 - net.ipv6.ioam6_id_wide
 - net.ipv6.conf.XXX.ioam6_id_wide

The value of the first one represents the wide IOAM ID of the node itself (u64;
max and default value = U64_MAX>>8, due to hop limit concatenation) while the
other represents the wide IOAM ID of an interface (u32; max and default value
= U32_MAX).

The use of short and wide equivalents is not exclusive, a deployment could
choose to leverage both. For example, net.ipv6.conf.XXX.ioam6_id (short format)
could be an identifier for a physical interface, whereas
net.ipv6.conf.XXX.ioam6_id_wide (wide format) could be an identifier for a
logical sub-interface. Documentation about new sysctls is provided at the end
of this patchset.

Two relativistic hash tables are used: 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
  [2] https://tools.ietf.org/html/draft-ietf-ippm-ioam-data
  [3] https://www.iana.org/assignments/ipv6-parameters/ipv6-parameters.xhtml#ipv6-parameters-2

Signed-off-by: Justin Iurman <justin.iurman@uliege.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 0 deletions

diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c
index d7cf26f730d7..d53dd142bf87 100644
--- a/net/ipv6/sysctl_net_ipv6.c
+++ b/net/ipv6/sysctl_net_ipv6.c
@@ -21,6 +21,7 @@
 #ifdef CONFIG_NETLABEL
 #include <net/calipso.h>
 #endif
+#include <linux/ioam6.h>
 
 static int two = 2;
 static int three = 3;
@@ -28,6 +29,8 @@ static int flowlabel_reflect_max = 0x7;
 static int auto_flowlabels_max = IP6_AUTO_FLOW_LABEL_MAX;
 static u32 rt6_multipath_hash_fields_all_mask =
 	FIB_MULTIPATH_HASH_FIELD_ALL_MASK;
+static u32 ioam6_id_max = IOAM6_DEFAULT_ID;
+static u64 ioam6_id_wide_max = IOAM6_DEFAULT_ID_WIDE;
 
 static int proc_rt6_multipath_hash_policy(struct ctl_table *table, int write,
 					  void *buffer, size_t *lenp, loff_t *ppos)
@@ -196,6 +199,22 @@ static struct ctl_table ipv6_table_template[] = {
 		.extra1         = SYSCTL_ZERO,
 		.extra2         = &two,
 	},
+	{
+		.procname	= "ioam6_id",
+		.data		= &init_net.ipv6.sysctl.ioam6_id,
+		.maxlen		= sizeof(u32),
+		.mode		= 0644,
+		.proc_handler	= proc_douintvec_minmax,
+		.extra2		= &ioam6_id_max,
+	},
+	{
+		.procname	= "ioam6_id_wide",
+		.data		= &init_net.ipv6.sysctl.ioam6_id_wide,
+		.maxlen		= sizeof(u64),
+		.mode		= 0644,
+		.proc_handler	= proc_doulongvec_minmax,
+		.extra2		= &ioam6_id_wide_max,
+	},
 	{ }
 };