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, 37 insertions, 0 deletions

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index bc330fffb4a8..1802287977f1 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -89,12 +89,15 @@
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 #include <linux/export.h>
+#include <linux/ioam6.h>
 
 #define	INFINITY_LIFE_TIME	0xFFFFFFFF
 
 #define IPV6_MAX_STRLEN \
 	sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")
 
+static u32 ioam6_if_id_max = U16_MAX;
+
 static inline u32 cstamp_delta(unsigned long cstamp)
 {
 	return (cstamp - INITIAL_JIFFIES) * 100UL / HZ;
@@ -237,6 +240,9 @@ 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               = IOAM6_DEFAULT_IF_ID,
+	.ioam6_id_wide		= IOAM6_DEFAULT_IF_ID_WIDE,
 };
 
 static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
@@ -293,6 +299,9 @@ 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               = IOAM6_DEFAULT_IF_ID,
+	.ioam6_id_wide		= IOAM6_DEFAULT_IF_ID_WIDE,
 };
 
 /* Check if link is ready: is it up and is a valid qdisc available */
@@ -5524,6 +5533,9 @@ 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;
+	array[DEVCONF_IOAM6_ID_WIDE] = cnf->ioam6_id_wide;
 }
 
 static inline size_t inet6_ifla6_size(void)
@@ -6931,6 +6943,31 @@ static const struct ctl_table addrconf_sysctl[] = {
 		.proc_handler	= proc_dointvec,
 	},
 	{
+		.procname	= "ioam6_enabled",
+		.data		= &ipv6_devconf.ioam6_enabled,
+		.maxlen		= sizeof(u8),
+		.mode		= 0644,
+		.proc_handler	= proc_dou8vec_minmax,
+		.extra1		= (void *)SYSCTL_ZERO,
+		.extra2		= (void *)SYSCTL_ONE,
+	},
+	{
+		.procname	= "ioam6_id",
+		.data		= &ipv6_devconf.ioam6_id,
+		.maxlen		= sizeof(u32),
+		.mode		= 0644,
+		.proc_handler	= proc_douintvec_minmax,
+		.extra1		= (void *)SYSCTL_ZERO,
+		.extra2		= (void *)&ioam6_if_id_max,
+	},
+	{
+		.procname	= "ioam6_id_wide",
+		.data		= &ipv6_devconf.ioam6_id_wide,
+		.maxlen		= sizeof(u32),
+		.mode		= 0644,
+		.proc_handler	= proc_douintvec,
+	},
+	{
 		/* sentinel */
 	}
 };