cifs: Register generic netlink family

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

Signed-off-by: Samuel Cabrero <scabrero@suse.de>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/Kconfig b/fs/cifs/Kconfig
index 604f65f4b6c5717c5d3a08cd13e1dc84fc836be0..664ac5c63d39752d577a7302bd407a63a32358c5 100644 (file)
--- 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 848ebad6af7dbbe375ebeaa8c015a2188afd9222..9e398d227b0e4637eb63cff4568bc7aa6cd0de61 100644 (file)
--- 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 4f27f77d3053ab896e9d8c4128e0f8a1e57351d6..5d32561ae2ed6edfb036930440f9cbddd38e2770 100644 (file)
--- 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
 #include "fs_context.h"
 
 /*
@@ -1601,10 +1604,15 @@ 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)
@@ -1620,7 +1628,11 @@ 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:
@@ -1657,6 +1669,9 @@ 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 (file)
index 0000000..b915466
--- /dev/null
+++ b/fs/cifs/netlink.c
@@ -0,0 +1,69 @@
+// 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 "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 (file)
index 0000000..e2fa8ed
--- /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 (file)
index 0000000..cdb1bd7
--- /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 */