[patch iproute2-next 2/4] devlink: introduce support for netns id for nested handle

[Jiri Pirko <jiri@resnulli.us>]

From: Jiri Pirko <jiri@nvidia.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@nvidia.com>
---
 devlink/devlink.c | 105 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 105 insertions(+)

diff --git a/devlink/devlink.c b/devlink/devlink.c
index d1795f616ca0..31dd29452c39 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 +2725,85 @@ static bool should_arr_last_handle_end(struct dl *dl, const char *bus_name,
 	       !cmp_arr_last_handle(dl, bus_name, dev_name);
 }
 
+static int32_t netns_id_by_name(const char *name)
+{
+	struct {
+		struct nlmsghdr n;
+		struct rtgenmsg g;
+		char            buf[1024];
+	} req = {
+		.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtgenmsg)),
+		.n.nlmsg_flags = NLM_F_REQUEST,
+		.n.nlmsg_type = RTM_GETNSID,
+		.g.rtgen_family = AF_UNSPEC,
+	};
+	int ret = NETNSA_NSID_NOT_ASSIGNED;
+	struct rtattr *tb[NETNSA_MAX + 1];
+	struct nlmsghdr *n = NULL;
+	struct rtnl_handle rth;
+	struct rtgenmsg *rtg;
+	int len;
+	int fd;
+
+	fd = netns_get_fd(name);
+	if (fd < 0)
+		return ret;
+
+	if (rtnl_open(&rth, 0) < 0)
+		return ret;
+
+	addattr32(&req.n, sizeof(req), NETNSA_FD, fd);
+	if (rtnl_talk(&rth, &req.n, &n) < 0)
+		goto out;
+
+	if (n->nlmsg_type == NLMSG_ERROR)
+		goto out;
+
+	rtg = NLMSG_DATA(n);
+	len = n->nlmsg_len;
+
+	len -= NLMSG_SPACE(sizeof(*rtg));
+	if (len < 0)
+		goto out;
+
+	parse_rtattr(tb, NETNSA_MAX, NETNS_RTA(rtg), len);
+	if (tb[NETNSA_NSID])
+		ret = rta_getattr_s32(tb[NETNSA_NSID]);
+
+out:
+	free(n);
+	rtnl_close(&rth);
+	close(fd);
+	return ret;
+}
+
+struct netns_name_by_id_ctx {
+	int32_t id;
+	char *name;
+};
+
+static int nesns_name_by_id_func(char *nsname, void *arg)
+{
+	struct netns_name_by_id_ctx *ctx = arg;
+	int32_t ret;
+
+	ret = netns_id_by_name(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 netns_name_by_id_ctx ctx = {
+		.id = id,
+	};
+
+	netns_foreach(nesns_name_by_id_func, &ctx);
+	return ctx.name;
+}
+
 static void pr_out_nested_handle(struct nlattr *nla_nested_dl)
 {
 	struct nlattr *tb[DEVLINK_ATTR_MAX + 1] = {};
@@ -2740,6 +2821,30 @@ 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