[PATCH v2 03/11] cifs: Register generic netlink family

Samuel Cabrero
2020-10-27T10:08:32Z

Register a new generic netlink family to talk to the witness service
userspace daemon.

Signed-off-by: Samuel Cabrero <scabrero@suse.de>
---
fs/cifs/Kconfig | 11 +++++
fs/cifs/Makefile | 2 +
fs/cifs/cifsfs.c | 17 ++++++-
fs/cifs/netlink.c | 68 ++++++++++++++++++++++++++
fs/cifs/netlink.h | 16 ++++++
include/uapi/linux/cifs/cifs_netlink.h | 31 ++++++++++++
6 files changed, 144 insertions(+), 1 deletion(-)
create mode 100644 fs/cifs/netlink.c
create mode 100644 fs/cifs/netlink.h
create mode 100644 include/uapi/linux/cifs/cifs_netlink.h

diff --git a/fs/cifs/Kconfig b/fs/cifs/Kconfig
index 604f65f4b6c5..664ac5c63d39 100644
--- a/fs/cifs/Kconfig
+++ b/fs/cifs/Kconfig
@@ -190,6 +190,17 @@ config CIFS_DFS_UPCALL
servers if their addresses change or for implicit mounts of
DFS junction points. If unsure, say Y.

+config CIFS_SWN_UPCALL
+ bool "SWN feature support"
+ depends on CIFS
+ help
+ The Service Witness Protocol (SWN) is used to get notifications
+ from a highly available server of resource state changes. This
+ feature enables an upcall mechanism for CIFS which contacts an
+ userspace daemon to establish the DCE/RPC connection to retrieve
+ the cluster available interfaces and resource change notifications.
+ If unsure, say Y.
+
config CIFS_NFSD_EXPORT
bool "Allow nfsd to export CIFS file system"
depends on CIFS && BROKEN
diff --git a/fs/cifs/Makefile b/fs/cifs/Makefile
index cd17d0e50f2a..b88fd46ac597 100644
--- a/fs/cifs/Makefile
+++ b/fs/cifs/Makefile
@@ -18,6 +18,8 @@ cifs-$(CONFIG_CIFS_UPCALL) += cifs_spnego.o

cifs-$(CONFIG_CIFS_DFS_UPCALL) += dns_resolve.o cifs_dfs_ref.o dfs_cache.o

+cifs-$(CONFIG_CIFS_SWN_UPCALL) += netlink.o
+
cifs-$(CONFIG_CIFS_FSCACHE) += fscache.o cache.o

cifs-$(CONFIG_CIFS_SMB_DIRECT) += smbdirect.o
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 472cb7777e3e..8111d0109a2e 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -55,6 +55,9 @@
#ifdef CONFIG_CIFS_DFS_UPCALL
#include "dfs_cache.h"
#endif
+#ifdef CONFIG_CIFS_SWN_UPCALL
+#include "netlink.h"
+#endif

/*
* DOS dates from 1980/1/1 through 2107/12/31
@@ -1617,10 +1620,15 @@ init_cifs(void)
if (rc)
goto out_destroy_dfs_cache;
#endif /* CONFIG_CIFS_UPCALL */
+#ifdef CONFIG_CIFS_SWN_UPCALL
+ rc = cifs_genl_init();
+ if (rc)
+ goto out_register_key_type;
+#endif /* CONFIG_CIFS_SWN_UPCALL */

rc = init_cifs_idmap();
if (rc)
- goto out_register_key_type;
+ goto out_cifs_swn_init;

rc = register_filesystem(&cifs_fs_type);
if (rc)
@@ -1636,7 +1644,11 @@ init_cifs(void)

out_init_cifs_idmap:
exit_cifs_idmap();
+out_cifs_swn_init:
+#ifdef CONFIG_CIFS_SWN_UPCALL
+ cifs_genl_exit();
out_register_key_type:
+#endif
#ifdef CONFIG_CIFS_UPCALL
exit_cifs_spnego();
out_destroy_dfs_cache:
@@ -1673,6 +1685,9 @@ exit_cifs(void)
unregister_filesystem(&smb3_fs_type);
cifs_dfs_release_automount_timer();
exit_cifs_idmap();
+#ifdef CONFIG_CIFS_SWN_UPCALL
+ cifs_genl_exit();
+#endif
#ifdef CONFIG_CIFS_UPCALL
exit_cifs_spnego();
#endif
diff --git a/fs/cifs/netlink.c b/fs/cifs/netlink.c
new file mode 100644
index 000000000000..5cd5dfee1132
--- /dev/null
+++ b/fs/cifs/netlink.c
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Netlink routines for CIFS
+ *
+ * Copyright (c) 2020 Samuel Cabrero <scabrero@suse.de>
+ */
+
+#include <net/genetlink.h>
+#include <uapi/linux/cifs/cifs_netlink.h>
+
+#include "cifsglob.h"
+#include "cifs_debug.h"
+
+static const struct nla_policy cifs_genl_policy[CIFS_GENL_ATTR_MAX + 1] = {
+};
+
+static struct genl_ops cifs_genl_ops[] = {
+};
+
+static const struct genl_multicast_group cifs_genl_mcgrps[] = {
+ [CIFS_GENL_MCGRP_SWN] = { .name = CIFS_GENL_MCGRP_SWN_NAME },
+};
+
+struct genl_family cifs_genl_family = {
+ .name = CIFS_GENL_NAME,
+ .version = CIFS_GENL_VERSION,
+ .hdrsize = 0,
+ .maxattr = CIFS_GENL_ATTR_MAX,
+ .module = THIS_MODULE,
+ .policy = cifs_genl_policy,
+ .ops = cifs_genl_ops,
+ .n_ops = ARRAY_SIZE(cifs_genl_ops),
+ .mcgrps = cifs_genl_mcgrps,
+ .n_mcgrps = ARRAY_SIZE(cifs_genl_mcgrps),
+};
+
+/**
+ * cifs_genl_init - Register generic netlink family
+ *
+ * Return zero if initialized successfully, otherwise non-zero.
+ */
+int cifs_genl_init(void)
+{
+ int ret;
+
+ ret = genl_register_family(&cifs_genl_family);
+ if (ret < 0) {
+ cifs_dbg(VFS, "%s: failed to register netlink family\n",
+ __func__);
+ return ret;
+ }
+
+ return 0;
+}
+
+/**
+ * cifs_genl_exit - Unregister generic netlink family
+ */
+void cifs_genl_exit(void)
+{
+ int ret;
+
+ ret = genl_unregister_family(&cifs_genl_family);
+ if (ret < 0) {
+ cifs_dbg(VFS, "%s: failed to unregister netlink family\n",
+ __func__);
+ }
+}
diff --git a/fs/cifs/netlink.h b/fs/cifs/netlink.h
new file mode 100644
index 000000000000..e2fa8ed24c54
--- /dev/null
+++ b/fs/cifs/netlink.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Netlink routines for CIFS
+ *
+ * Copyright (c) 2020 Samuel Cabrero <scabrero@suse.de>
+ */
+
+#ifndef _CIFS_NETLINK_H
+#define _CIFS_NETLINK_H
+
+extern struct genl_family cifs_genl_family;
+
+extern int cifs_genl_init(void);
+extern void cifs_genl_exit(void);
+
+#endif /* _CIFS_NETLINK_H */
diff --git a/include/uapi/linux/cifs/cifs_netlink.h b/include/uapi/linux/cifs/cifs_netlink.h
new file mode 100644
index 000000000000..cdb1bd78fbc7
--- /dev/null
+++ b/include/uapi/linux/cifs/cifs_netlink.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: LGPL-2.1+ WITH Linux-syscall-note */
+/*
+ * Netlink routines for CIFS
+ *
+ * Copyright (c) 2020 Samuel Cabrero <scabrero@suse.de>
+ */
+
+
+#ifndef _UAPILINUX_CIFS_NETLINK_H
+#define _UAPILINUX_CIFS_NETLINK_H
+
+#define CIFS_GENL_NAME "cifs"
+#define CIFS_GENL_VERSION 0x1
+
+#define CIFS_GENL_MCGRP_SWN_NAME "cifs_mcgrp_swn"
+
+enum cifs_genl_multicast_groups {
+ CIFS_GENL_MCGRP_SWN,
+};
+
+enum cifs_genl_attributes {
+ __CIFS_GENL_ATTR_MAX,
+};
+#define CIFS_GENL_ATTR_MAX (__CIFS_GENL_ATTR_MAX - 1)
+
+enum cifs_genl_commands {
+ __CIFS_GENL_CMD_MAX
+};
+#define CIFS_GENL_CMD_MAX (__CIFS_GENL_CMD_MAX - 1)
+
+#endif /* _UAPILINUX_CIFS_NETLINK_H */
--
2.29.0