smb3: create smb3 equivalent alias for cifs pseudo-xattrs

We really, really don't want to be encouraging people to use
cifs (the dialect) since it is insecure, so to avoid confusion
we want to move them to names which include 'smb3' instead of
'cifs' - so this simply creates an alias for the pseudo-xattrs

e.g. can now do:
getfattr -n user.smb3.creationtime /mnt1/file
and
getfattr -n user.smb3.dosattrib /mnt1/file
and
getfattr -n system.smb3_acl /mnt1/file

instead of forcing you to use the string 'cifs' in
these (e.g. getfattr -n system.cifs_acl /mnt1/file)

Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/xattr.c

@@ -35,6 +35,14 @@
 #define CIFS_XATTR_CIFS_ACL "system.cifs_acl"
 #define CIFS_XATTR_ATTRIB "cifs.dosattrib"  /* full name: user.cifs.dosattrib */
 #define CIFS_XATTR_CREATETIME "cifs.creationtime"  /* user.cifs.creationtime */
+/*
+ * Although these three are just aliases for the above, need to move away from
+ * confusing users and using the 20+ year old term 'cifs' when it is no longer
+ * secure, replaced by SMB2 (then even more highly secure SMB3) many years ago
+ */
+#define SMB3_XATTR_CIFS_ACL "system.smb3_acl"
+#define SMB3_XATTR_ATTRIB "smb3.dosattrib"  /* full name: user.smb3.dosattrib */
+#define SMB3_XATTR_CREATETIME "smb3.creationtime"  /* user.smb3.creationtime */
 /* BB need to add server (Samba e.g) support for security and trusted prefix */
 
 enum { XATTR_USER, XATTR_CIFS_ACL, XATTR_ACL_ACCESS, XATTR_ACL_DEFAULT };
@@ -220,10 +228,12 @@ static int cifs_xattr_get(const struct xattr_handler *handler,
 	switch (handler->flags) {
 	case XATTR_USER:
 		cifs_dbg(FYI, "%s:querying user xattr %s\n", __func__, name);
-		if (strcmp(name, CIFS_XATTR_ATTRIB) == 0) {
+		if ((strcmp(name, CIFS_XATTR_ATTRIB) == 0) ||
+		    (strcmp(name, SMB3_XATTR_ATTRIB) == 0)) {
 			rc = cifs_attrib_get(dentry, inode, value, size);
 			break;
-		} else if (strcmp(name, CIFS_XATTR_CREATETIME) == 0) {
+		} else if ((strcmp(name, CIFS_XATTR_CREATETIME) == 0) ||
+		    (strcmp(name, SMB3_XATTR_CREATETIME) == 0)) {
 			rc = cifs_creation_time_get(dentry, inode, value, size);
 			break;
 		}
@@ -363,6 +373,19 @@ static const struct xattr_handler cifs_cifs_acl_xattr_handler = {
 	.set = cifs_xattr_set,
 };
 
+/*
+ * Although this is just an alias for the above, need to move away from
+ * confusing users and using the 20 year old term 'cifs' when it is no
+ * longer secure and was replaced by SMB2/SMB3 a long time ago, and
+ * SMB3 and later are highly secure.
+ */
+static const struct xattr_handler smb3_acl_xattr_handler = {
+	.name = SMB3_XATTR_CIFS_ACL,
+	.flags = XATTR_CIFS_ACL,
+	.get = cifs_xattr_get,
+	.set = cifs_xattr_set,
+};
+
 static const struct xattr_handler cifs_posix_acl_access_xattr_handler = {
 	.name = XATTR_NAME_POSIX_ACL_ACCESS,
 	.flags = XATTR_ACL_ACCESS,
@@ -381,6 +404,7 @@ const struct xattr_handler *cifs_xattr_handlers[] = {
 	&cifs_user_xattr_handler,
 	&cifs_os2_xattr_handler,
 	&cifs_cifs_acl_xattr_handler,
+	&smb3_acl_xattr_handler, /* alias for above since avoiding "cifs" */
 	&cifs_posix_acl_access_xattr_handler,
 	&cifs_posix_acl_default_xattr_handler,
 	NULL