[J][PATCH 3/3] net/smc: add generic netlink support for system EID

[frank.heimes at canonical.com]

From: Karsten Graul <kgraul at linux.ibm.com>

BugLink: https://bugs.launchpad.net/bugs/1929060

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: Karsten Graul <kgraul at linux.ibm.com>
Reviewed-by: Guvenc Gulce  <guvenc at linux.ibm.com>
Signed-off-by: Guvenc Gulce <guvenc at linux.ibm.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
(cherry picked from commit 3c572145c24e21c24e1cd0fd168011eaba85da8e)
Signed-off-by: Frank Heimes <frank.heimes at canonical.com>
---
 include/uapi/linux/smc.h | 12 ++++++++
 net/smc/smc_clc.c        | 62 ++++++++++++++++++++++++++++++++++++++++
 net/smc/smc_clc.h        |  3 ++
 net/smc/smc_netlink.c    | 15 ++++++++++
 4 files changed, 92 insertions(+)

diff --git a/include/uapi/linux/smc.h b/include/uapi/linux/smc.h
index e3728af2832b..b175bd0165a1 100644
--- a/include/uapi/linux/smc.h
+++ b/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 */
diff --git a/net/smc/smc_clc.c b/net/smc/smc_clc.c
index 110c2ef45a3f..1cc8a76b39f9 100644
--- a/net/smc/smc_clc.c
+++ b/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;
diff --git a/net/smc/smc_clc.h b/net/smc/smc_clc.h
index 0699e0cee308..974d01d16bb5 100644
--- a/net/smc/smc_clc.h
+++ b/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
diff --git a/net/smc/smc_netlink.c b/net/smc/smc_netlink.c
index 4548ff2df245..f13ab0661ed5 100644
--- a/net/smc/smc_netlink.c
+++ b/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] = {
-- 
2.25.1