tcp_metrics: add netlink protocol spec in YAML

Add a protocol spec for tcp_metrics, so that it's accessible via YNL.
Useful at the very least for testing fixes.

In this episode of "10,000 ways to complicate netlink" the metric
nest has defines which are off by 1. iproute2 does:

        struct rtattr *m[TCP_METRIC_MAX + 1 + 1];

        parse_rtattr_nested(m, TCP_METRIC_MAX + 1, a);

        for (i = 0; i < TCP_METRIC_MAX + 1; i++) {
                // ...
                attr = m[i + 1];

This is too weird to support in YNL, add a new set of defines
with _correct_ values to the official kernel header.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/Documentation/netlink/specs/tcp_metrics.yaml b/Documentation/netlink/specs/tcp_metrics.yaml
new file mode 100644 (file)
index 0000000..1bd94f4
--- /dev/null
+++ b/Documentation/netlink/specs/tcp_metrics.yaml
@@ -0,0 +1,169 @@
+# SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
+
+name: tcp_metrics
+
+protocol: genetlink-legacy
+
+doc: |
+  Management interface for TCP metrics.
+
+c-family-name: tcp-metrics-genl-name
+c-version-name: tcp-metrics-genl-version
+max-by-define: true
+kernel-policy: global
+
+definitions:
+  -
+    name: tcp-fastopen-cookie-max
+    type: const
+    value: 16
+
+attribute-sets:
+  -
+    name: tcp-metrics
+    name-prefix: tcp-metrics-attr-
+    attributes:
+      -
+        name: addr-ipv4
+        type: u32
+        byte-order: big-endian
+        display-hint: ipv4
+      -
+        name: addr-ipv6
+        type: binary
+        checks:
+          min-len: 16
+        byte-order: big-endian
+        display-hint: ipv6
+      -
+        name: age
+        type: u64
+      -
+        name: tw-tsval
+        type: u32
+        doc: unused
+      -
+        name: tw-ts-stamp
+        type: s32
+        doc: unused
+      -
+        name: vals
+        type: nest
+        nested-attributes: metrics
+      -
+        name: fopen-mss
+        type: u16
+      -
+        name: fopen-syn-drops
+        type: u16
+      -
+        name: fopen-syn-drop-ts
+        type: u64
+      -
+        name: fopen-cookie
+        type: binary
+        checks:
+          min-len: tcp-fastopen-cookie-max
+      -
+        name: saddr-ipv4
+        type: u32
+        byte-order: big-endian
+        display-hint: ipv4
+      -
+        name: saddr-ipv6
+        type: binary
+        checks:
+          min-len: 16
+        byte-order: big-endian
+        display-hint: ipv6
+      -
+        name: pad
+        type: pad
+
+  -
+    name: metrics
+    # Intentionally don't define the name-prefix, see below.
+    doc: |
+      Attributes with metrics. Note that the values here do not match
+      the TCP_METRIC_* defines in the kernel, because kernel defines
+      are off-by one (e.g. rtt is defined as enum 0, while netlink carries
+      attribute type 1).
+    attributes:
+      -
+        name: rtt
+        type: u32
+        doc: |
+          Round Trip Time (RTT), in msecs with 3 bits fractional
+          (left-shift by 3 to get the msec value).
+      -
+        name: rttvar
+        type: u32
+        doc: |
+          Round Trip Time VARiance (RTT), in msecs with 2 bits fractional
+          (left-shift by 2 to get the msec value).
+      -
+        name: ssthresh
+        type: u32
+        doc: Slow Start THRESHold.
+      -
+        name: cwnd
+        type: u32
+        doc: Congestion Window.
+      -
+        name: reodering
+        type: u32
+        doc: Reodering metric.
+      -
+        name: rtt-us
+        type: u32
+        doc: |
+          Round Trip Time (RTT), in usecs, with 3 bits fractional
+          (left-shift by 3 to get the msec value).
+      -
+        name: rttvar-us
+        type: u32
+        doc: |
+          Round Trip Time (RTT), in usecs, with 2 bits fractional
+          (left-shift by 3 to get the msec value).
+
+operations:
+  list:
+    -
+      name: get
+      doc: Retrieve metrics.
+      attribute-set: tcp-metrics
+
+      dont-validate: [ strict, dump ]
+
+      do:
+        request: &sel_attrs
+          attributes:
+            - addr-ipv4
+            - addr-ipv6
+            - saddr-ipv4
+            - saddr-ipv6
+        reply: &all_attrs
+          attributes:
+            - addr-ipv4
+            - addr-ipv6
+            - saddr-ipv4
+            - saddr-ipv6
+            - age
+            - vals
+            - fopen-mss
+            - fopen-syn-drops
+            - fopen-syn-drop-ts
+            - fopen-cookie
+      dump:
+        reply: *all_attrs
+
+    -
+      name: del
+      doc: Delete metrics.
+      attribute-set: tcp-metrics
+
+      dont-validate: [ strict, dump ]
+      flags: [ admin-perm ]
+
+      do:
+        request: *sel_attrs

diff --git a/include/uapi/linux/tcp_metrics.h b/include/uapi/linux/tcp_metrics.h
index c48841076998b781e85846c0626b2278cef25313..927c735a5b0ef5cec144e9823e0d8e8245d6d0ac 100644 (file)
--- a/include/uapi/linux/tcp_metrics.h
+++ b/include/uapi/linux/tcp_metrics.h
@@ -27,6 +27,22 @@ enum tcp_metric_index {
 
 #define TCP_METRIC_MAX (__TCP_METRIC_MAX - 1)
 
+/* Re-define enum tcp_metric_index, again, using the values carried
+ * as netlink attribute types.
+ */
+enum {
+       TCP_METRICS_A_METRICS_RTT = 1,
+       TCP_METRICS_A_METRICS_RTTVAR,
+       TCP_METRICS_A_METRICS_SSTHRESH,
+       TCP_METRICS_A_METRICS_CWND,
+       TCP_METRICS_A_METRICS_REODERING,
+       TCP_METRICS_A_METRICS_RTT_US,
+       TCP_METRICS_A_METRICS_RTTVAR_US,
+
+       __TCP_METRICS_A_METRICS_MAX
+};
+#define TCP_METRICS_A_METRICS_MAX (__TCP_METRICS_A_METRICS_MAX - 1)
+
 enum {
        TCP_METRICS_ATTR_UNSPEC,
        TCP_METRICS_ATTR_ADDR_IPV4,             /* u32 */

diff --git a/tools/net/ynl/Makefile.deps b/tools/net/ynl/Makefile.deps
index dbdca32a1c612da41126066a5e3df4dee6d8bbaf..0712b5e82eb7984e859e30e4fd36fa6d85fd25e2 100644 (file)
--- a/tools/net/ynl/Makefile.deps
+++ b/tools/net/ynl/Makefile.deps
@@ -26,3 +26,4 @@ CFLAGS_nfsd:=$(call get_hdr_inc,_LINUX_NFSD_NETLINK_H,nfsd_netlink.h)
 CFLAGS_ovs_datapath:=$(call get_hdr_inc,__LINUX_OPENVSWITCH_H,openvswitch.h)
 CFLAGS_ovs_flow:=$(call get_hdr_inc,__LINUX_OPENVSWITCH_H,openvswitch.h)
 CFLAGS_ovs_vport:=$(call get_hdr_inc,__LINUX_OPENVSWITCH_H,openvswitch.h)
+CFLAGS_tcp_metrics:=$(call get_hdr_inc,_LINUX_TCP_METRICS_H,tcp_metrics.h)