netdev - [patch iproute2-next v2 3/5] devlink: introduce support for netns id for nested handle

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Date: Tue, 19 Sep 2023 13:56:42 +0200
From: Jiri Pirko <jiri@...nulli.us>
To: netdev@...r.kernel.org
Cc: stephen@...workplumber.org,
	dsahern@...il.com,
	daniel.machon@...rochip.com
Subject: [patch iproute2-next v2 3/5] devlink: introduce support for netns id for nested handle

From: Jiri Pirko <jiri@...dia.com>

Nested handle may contain DEVLINK_ATTR_NETNS_ID attribute that indicates
the network namespace where the nested devlink instance resides. Process
this converting to netns name if possible and print to user.

Signed-off-by: Jiri Pirko <jiri@...dia.com>
---
v1->v2:
- use previously introduced netns_netnsid_from_name() instead of code
  duplication for the same function.
- s/nesns_name_by_id_func/netns_name_by_id_func/
---
 devlink/devlink.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/devlink/devlink.c b/devlink/devlink.c
index d1795f616ca0..cf5d466bfc9d 100644
--- a/devlink/devlink.c
+++ b/devlink/devlink.c
@@ -24,6 +24,7 @@
 #include <linux/genetlink.h>
 #include <linux/devlink.h>
 #include <linux/netlink.h>
+#include <linux/net_namespace.h>
 #include <libmnl/libmnl.h>
 #include <netinet/ether.h>
 #include <sys/select.h>
@@ -722,6 +723,7 @@ static const enum mnl_attr_data_type devlink_policy[DEVLINK_ATTR_MAX + 1] = {
 	[DEVLINK_ATTR_LINECARD_SUPPORTED_TYPES] = MNL_TYPE_NESTED,
 	[DEVLINK_ATTR_NESTED_DEVLINK] = MNL_TYPE_NESTED,
 	[DEVLINK_ATTR_SELFTESTS] = MNL_TYPE_NESTED,
+	[DEVLINK_ATTR_NETNS_ID] = MNL_TYPE_U32,
 };
 
 static const enum mnl_attr_data_type
@@ -2723,6 +2725,40 @@ static bool should_arr_last_handle_end(struct dl *dl, const char *bus_name,
 	       !cmp_arr_last_handle(dl, bus_name, dev_name);
 }
 
+struct netns_name_by_id_ctx {
+	int32_t id;
+	char *name;
+	struct rtnl_handle *rth;
+};
+
+static int netns_name_by_id_func(char *nsname, void *arg)
+{
+	struct netns_name_by_id_ctx *ctx = arg;
+	int32_t ret;
+
+	ret = netns_netnsid_from_name(ctx->rth, nsname);
+	if (ret < 0 || ret != ctx->id)
+		return 0;
+	ctx->name = strdup(nsname);
+	return 1;
+}
+
+static char *netns_name_by_id(int32_t id)
+{
+	struct rtnl_handle rth;
+	struct netns_name_by_id_ctx ctx = {
+		.id = id,
+		.rth = &rth,
+	};
+
+	if (rtnl_open(&rth, 0) < 0)
+		return NULL;
+	netns_foreach(netns_name_by_id_func, &ctx);
+	rtnl_close(&rth);
+
+	return ctx.name;
+}
+
 static void pr_out_nested_handle(struct nlattr *nla_nested_dl)
 {
 	struct nlattr *tb[DEVLINK_ATTR_MAX + 1] = {};
@@ -2740,6 +2776,30 @@ static void pr_out_nested_handle(struct nlattr *nla_nested_dl)
 	sprintf(buf, "%s/%s", mnl_attr_get_str(tb[DEVLINK_ATTR_BUS_NAME]),
 		mnl_attr_get_str(tb[DEVLINK_ATTR_DEV_NAME]));
 	print_string(PRINT_ANY, "nested_devlink", " nested_devlink %s", buf);
+
+	if (tb[DEVLINK_ATTR_NETNS_ID]) {
+		int32_t id = mnl_attr_get_u32(tb[DEVLINK_ATTR_NETNS_ID]);
+
+		if (id >= 0) {
+			char *name = netns_name_by_id(id);
+
+			if (name) {
+				print_string(PRINT_ANY,
+					     "nested_devlink_netns",
+					     " nested_devlink_netns %s", name);
+				free(name);
+			} else {
+				print_int(PRINT_ANY,
+					  "nested_devlink_netnsid",
+					  " nested_devlink_netnsid %d", id);
+			}
+		} else {
+			print_string(PRINT_FP, NULL,
+				     " nested_devlink_netnsid %s", "unknown");
+			print_int(PRINT_JSON,
+				  "nested_devlink_netnsid", NULL, id);
+		}
+	}
 }
 
 static void __pr_out_handle_start(struct dl *dl, struct nlattr **tb,
-- 
2.41.0