net/smc: add generic netlink support for system EID

With SMC-Dv2 users can configure if the static system EID should be used
during CLC handshake, or if only user EIDs are allowed.
Add generic netlink support to enable and disable the system EID, and
to retrieve the system EID and its current enabled state.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NGuvenc Gulce  <guvenc@linux.ibm.com>
Signed-off-by: NGuvenc Gulce <guvenc@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/uapi/linux/smc.h

@@ -56,6 +56,9 @@ enum {
 	SMC_NETLINK_ADD_UEID,
 	SMC_NETLINK_REMOVE_UEID,
 	SMC_NETLINK_FLUSH_UEID,
+	SMC_NETLINK_DUMP_SEID,
+	SMC_NETLINK_ENABLE_SEID,
+	SMC_NETLINK_DISABLE_SEID,
 };
 
 /* SMC_GENL_FAMILY top level attributes */
@@ -257,4 +260,13 @@ enum {
 	__SMC_NLA_EID_TABLE_MAX,
 	SMC_NLA_EID_TABLE_MAX = __SMC_NLA_EID_TABLE_MAX - 1
 };
+
+/* SMC_NETLINK_SEID attributes */
+enum {
+	SMC_NLA_SEID_UNSPEC,
+	SMC_NLA_SEID_ENTRY,	/* string */
+	SMC_NLA_SEID_ENABLED,	/* u8 */
+	__SMC_NLA_SEID_TABLE_MAX,
+	SMC_NLA_SEID_TABLE_MAX = __SMC_NLA_SEID_TABLE_MAX - 1
+};
 #endif /* _UAPI_LINUX_SMC_H */

net/smc/smc_clc.c

@@ -143,6 +143,10 @@ static int smc_clc_ueid_remove(char *ueid)
 			rc = 0;
 		}
 	}
+	if (!rc && !smc_clc_eid_table.ueid_cnt) {
+		smc_clc_eid_table.seid_enabled = 1;
+		rc = -EAGAIN;	/* indicate success and enabling of seid */
+	}
 	write_unlock(&smc_clc_eid_table.lock);
 	return rc;
 }
@@ -216,6 +220,64 @@ int smc_nl_dump_ueid(struct sk_buff *skb, struct netlink_callback *cb)
 	return skb->len;
 }
 
+int smc_nl_dump_seid(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	struct smc_nl_dmp_ctx *cb_ctx = smc_nl_dmp_ctx(cb);
+	char seid_str[SMC_MAX_EID_LEN + 1];
+	u8 seid_enabled;
+	void *hdr;
+	u8 *seid;
+
+	if (cb_ctx->pos[0])
+		return skb->len;
+
+	hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
+			  &smc_gen_nl_family, NLM_F_MULTI,
+			  SMC_NETLINK_DUMP_SEID);
+	if (!hdr)
+		return -ENOMEM;
+	if (!smc_ism_is_v2_capable())
+		goto end;
+
+	smc_ism_get_system_eid(&seid);
+	snprintf(seid_str, sizeof(seid_str), "%s", seid);
+	if (nla_put_string(skb, SMC_NLA_SEID_ENTRY, seid_str))
+		goto err;
+	read_lock(&smc_clc_eid_table.lock);
+	seid_enabled = smc_clc_eid_table.seid_enabled;
+	read_unlock(&smc_clc_eid_table.lock);
+	if (nla_put_u8(skb, SMC_NLA_SEID_ENABLED, seid_enabled))
+		goto err;
+end:
+	genlmsg_end(skb, hdr);
+	cb_ctx->pos[0]++;
+	return skb->len;
+err:
+	genlmsg_cancel(skb, hdr);
+	return -EMSGSIZE;
+}
+
+int smc_nl_enable_seid(struct sk_buff *skb, struct genl_info *info)
+{
+	write_lock(&smc_clc_eid_table.lock);
+	smc_clc_eid_table.seid_enabled = 1;
+	write_unlock(&smc_clc_eid_table.lock);
+	return 0;
+}
+
+int smc_nl_disable_seid(struct sk_buff *skb, struct genl_info *info)
+{
+	int rc = 0;
+
+	write_lock(&smc_clc_eid_table.lock);
+	if (!smc_clc_eid_table.ueid_cnt)
+		rc = -ENOENT;
+	else
+		smc_clc_eid_table.seid_enabled = 0;
+	write_unlock(&smc_clc_eid_table.lock);
+	return rc;
+}
+
 static bool _smc_clc_match_ueid(u8 *peer_ueid)
 {
 	struct smc_clc_eid_entry *tmp_ueid;

net/smc/smc_clc.h

@@ -347,5 +347,8 @@ int smc_nl_dump_ueid(struct sk_buff *skb, struct netlink_callback *cb);
 int smc_nl_add_ueid(struct sk_buff *skb, struct genl_info *info);
 int smc_nl_remove_ueid(struct sk_buff *skb, struct genl_info *info);
 int smc_nl_flush_ueid(struct sk_buff *skb, struct genl_info *info);
+int smc_nl_dump_seid(struct sk_buff *skb, struct netlink_callback *cb);
+int smc_nl_enable_seid(struct sk_buff *skb, struct genl_info *info);
+int smc_nl_disable_seid(struct sk_buff *skb, struct genl_info *info);
 
 #endif

net/smc/smc_netlink.c

@@ -96,6 +96,21 @@ static const struct genl_ops smc_gen_nl_ops[] = {
 		.flags = GENL_ADMIN_PERM,
 		.doit = smc_nl_flush_ueid,
 	},
+	{
+		.cmd = SMC_NETLINK_DUMP_SEID,
+		/* can be retrieved by unprivileged users */
+		.dumpit = smc_nl_dump_seid,
+	},
+	{
+		.cmd = SMC_NETLINK_ENABLE_SEID,
+		.flags = GENL_ADMIN_PERM,
+		.doit = smc_nl_enable_seid,
+	},
+	{
+		.cmd = SMC_NETLINK_DISABLE_SEID,
+		.flags = GENL_ADMIN_PERM,
+		.doit = smc_nl_disable_seid,
+	},
 };
 
 static const struct nla_policy smc_gen_nl_policy[2] = {