[PATCH 6.1 07/15] genetlink: add THIRD_GENL family

[Yana Bashlykova <yana2bsh@gmail.com>]

- New family with echo command
- Supports string and flag attributes
- Sysfs interface at /sys/kernel/third_genl/message

Signed-off-by: Yana Bashlykova <yana2bsh@gmail.com>
---
 .../net-pf-16-proto-16-family-PARALLEL_GENL.c | 103 ++++++++++++++++++
 1 file changed, 103 insertions(+)

diff --git a/drivers/net/genetlink/net-pf-16-proto-16-family-PARALLEL_GENL.c b/drivers/net/genetlink/net-pf-16-proto-16-family-PARALLEL_GENL.c
index cdedd77b2a1b..f651159a311c 100644
--- a/drivers/net/genetlink/net-pf-16-proto-16-family-PARALLEL_GENL.c
+++ b/drivers/net/genetlink/net-pf-16-proto-16-family-PARALLEL_GENL.c
@@ -152,10 +152,13 @@ static DEFINE_MUTEX(genl_mutex);
 
 #define PARALLEL_GENL_FAMILY_NAME "PARALLEL_GENL"
 
+#define THIRD_GENL_FAMILY_NAME "THIRD_GENL"
+
 #define PATH_GENL_TEST_NUM "/sys/kernel/genl_test/value"
 #define PATH_GENL_TEST_MES "/sys/kernel/genl_test/message"
 #define PATH_GENL_TEST_DEV "/sys/kernel/genl_test/some_info"
 #define PATH_PARALLEL_GENL_MES "/sys/kernel/parallel_genl/message"
+#define PATH_THIRD_GENL_MES "/sys/kernel/third_genl/message"
 
 // TEST_GENL
 enum {
@@ -205,6 +208,8 @@ static struct genl_family my_genl_family;
 
 static struct genl_family my_genl_family_parallel;
 
+static struct genl_family third_genl_family;
+
 enum my_multicast_groups {
 	MY_MCGRP_GENL,
 };
@@ -1077,6 +1082,94 @@ static struct genl_family my_genl_family_parallel = {
 	.n_mcgrps = ARRAY_SIZE(genl_many_mcgrps_two),
 };
 
+// THIRD_GENL
+enum {
+	THIRD_GENL_ATTR_UNSPEC,
+	THIRD_GENL_ATTR_DATA,
+	THIRD_GENL_ATTR_FLAG,
+	__THIRD_GENL_ATTR_MAX,
+};
+
+#define THIRD_GENL_ATTR_MAX (__THIRD_GENL_ATTR_MAX - 1)
+
+enum {
+	THIRD_GENL_CMD_UNSPEC,
+	THIRD_GENL_CMD_ECHO,
+	__THIRD_GENL_CMD_MAX,
+};
+
+#define THIRD_GENL_CMD_MAX (__THIRD_GENL_CMD_MAX - 1)
+
+static const struct nla_policy third_genl_policy[THIRD_GENL_ATTR_MAX + 1] = {
+	[THIRD_GENL_ATTR_UNSPEC] = { .type = NLA_UNSPEC },
+	[THIRD_GENL_ATTR_DATA] = { .type = NLA_STRING },
+	[THIRD_GENL_ATTR_FLAG] = { .type = NLA_FLAG },
+};
+
+// Functions for THIRD_GENL family
+static int third_genl_echo(struct sk_buff *skb, struct genl_info *info)
+{
+	struct sk_buff *msg;
+	void *data;
+	int ret;
+	char *str;
+
+	if (info->nlhdr->nlmsg_flags & NLM_F_ECHO) {
+		msg = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
+		if (!msg)
+			return -ENOMEM;
+
+		data = genlmsg_put_reply(msg, info, &my_genl_family, 0,
+					 THIRD_GENL_CMD_ECHO);
+		if (!data)
+			goto error;
+
+		str = "Hello from THIRD_GENL!";
+		strcpy(sysfs_data.third_genl_message, str);
+
+		ret = nla_put_string(msg, THIRD_GENL_ATTR_DATA, str);
+		if (ret < 0)
+			goto error;
+
+		ret = nla_put_flag(msg, THIRD_GENL_ATTR_FLAG);
+		if (ret < 0)
+			goto error;
+
+		genlmsg_end(msg, data);
+
+		genlmsg_reply(msg, info);
+	}
+
+	return 0;
+
+error:
+	nlmsg_free(msg);
+	return -EMSGSIZE;
+}
+
+// Generic Netlink operations for THIRD_GENL family
+static const struct genl_ops third_genl_ops[] = {
+	{
+		.cmd = THIRD_GENL_CMD_ECHO,
+		.flags = 0,
+		.policy = third_genl_policy,
+		.doit = third_genl_echo,
+		.dumpit = NULL,
+	},
+};
+
+// genl_family struct for THIRD_GENL family
+static struct genl_family third_genl_family = {
+	.hdrsize = 0,
+	.name = THIRD_GENL_FAMILY_NAME,
+	.version = 1,
+	.maxattr = THIRD_GENL_ATTR_MAX,
+	.netnsok = true,
+	.ops = third_genl_ops,
+	.n_ops = ARRAY_SIZE(third_genl_ops),
+	.policy = third_genl_policy,
+};
+
 // genl_family struct with incorrect name
 static struct genl_family incorrect_genl_family = {
 	.hdrsize = 0,
@@ -1144,8 +1237,16 @@ static int __init init_netlink(void)
 		goto failure_2;
 	}
 
+	rc = genl_register_family(&third_genl_family);
+	if (rc) {
+		pr_err("%s: Failed to register Generic Netlink family\n", __func__);
+		goto failure_3;
+	}
+
 	return 0;
 
+failure_3:
+	genl_unregister_family(&my_genl_family_parallel);
 failure_2:
 	genl_unregister_family(&my_genl_family);
 failure_1:
@@ -1311,6 +1412,7 @@ static int __init module_netlink_init(void)
 err_family:
 	genl_unregister_family(&my_genl_family);
 	genl_unregister_family(&my_genl_family_parallel);
+	genl_unregister_family(&third_genl_family);
 err_sysfs:
 	sysfs_remove_file(kobj_genl_test, &my_attr_u32_genl_test.attr);
 	sysfs_remove_file(kobj_genl_test, &my_attr_str_genl_test.attr);
@@ -1330,6 +1432,7 @@ static void __exit module_netlink_exit(void)
 	netlink_unregister_notifier(&genl_notifier);
 	genl_unregister_family(&my_genl_family);
 	genl_unregister_family(&my_genl_family_parallel);
+	genl_unregister_family(&third_genl_family);
 
 	sysfs_remove_file(kobj_genl_test, &my_attr_u32_genl_test.attr);
 	sysfs_remove_file(kobj_genl_test, &my_attr_str_genl_test.attr);
-- 
2.34.1