v4.19.13 snapshot.
diff --git a/include/linux/sunrpc/svcauth.h b/include/linux/sunrpc/svcauth.h
new file mode 100644
index 0000000..04e404a
--- /dev/null
+++ b/include/linux/sunrpc/svcauth.h
@@ -0,0 +1,189 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * linux/include/linux/sunrpc/svcauth.h
+ *
+ * RPC server-side authentication stuff.
+ *
+ * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
+ */
+
+#ifndef _LINUX_SUNRPC_SVCAUTH_H_
+#define _LINUX_SUNRPC_SVCAUTH_H_
+
+#ifdef __KERNEL__
+
+#include <linux/string.h>
+#include <linux/sunrpc/msg_prot.h>
+#include <linux/sunrpc/cache.h>
+#include <linux/sunrpc/gss_api.h>
+#include <linux/hash.h>
+#include <linux/stringhash.h>
+#include <linux/cred.h>
+
+struct svc_cred {
+	kuid_t			cr_uid;
+	kgid_t			cr_gid;
+	struct group_info	*cr_group_info;
+	u32			cr_flavor; /* pseudoflavor */
+	/* name of form servicetype/hostname@REALM, passed down by
+	 * gss-proxy: */
+	char			*cr_raw_principal;
+	/* name of form servicetype@hostname, passed down by
+	 * rpc.svcgssd, or computed from the above: */
+	char			*cr_principal;
+	char			*cr_targ_princ;
+	struct gss_api_mech	*cr_gss_mech;
+};
+
+static inline void init_svc_cred(struct svc_cred *cred)
+{
+	cred->cr_group_info = NULL;
+	cred->cr_raw_principal = NULL;
+	cred->cr_principal = NULL;
+	cred->cr_targ_princ = NULL;
+	cred->cr_gss_mech = NULL;
+}
+
+static inline void free_svc_cred(struct svc_cred *cred)
+{
+	if (cred->cr_group_info)
+		put_group_info(cred->cr_group_info);
+	kfree(cred->cr_raw_principal);
+	kfree(cred->cr_principal);
+	kfree(cred->cr_targ_princ);
+	gss_mech_put(cred->cr_gss_mech);
+	init_svc_cred(cred);
+}
+
+struct svc_rqst;		/* forward decl */
+struct in6_addr;
+
+/* Authentication is done in the context of a domain.
+ *
+ * Currently, the nfs server uses the auth_domain to stand
+ * for the "client" listed in /etc/exports.
+ *
+ * More generally, a domain might represent a group of clients using
+ * a common mechanism for authentication and having a common mapping
+ * between local identity (uid) and network identity.  All clients
+ * in a domain have similar general access rights.  Each domain can
+ * contain multiple principals which will have different specific right
+ * based on normal Discretionary Access Control.
+ *
+ * A domain is created by an authentication flavour module based on name
+ * only.  Userspace then fills in detail on demand.
+ *
+ * In the case of auth_unix and auth_null, the auth_domain is also
+ * associated with entries in another cache representing the mapping
+ * of ip addresses to the given client.
+ */
+struct auth_domain {
+	struct kref		ref;
+	struct hlist_node	hash;
+	char			*name;
+	struct auth_ops		*flavour;
+};
+
+/*
+ * Each authentication flavour registers an auth_ops
+ * structure.
+ * name is simply the name.
+ * flavour gives the auth flavour. It determines where the flavour is registered
+ * accept() is given a request and should verify it.
+ *   It should inspect the authenticator and verifier, and possibly the data.
+ *    If there is a problem with the authentication *authp should be set.
+ *    The return value of accept() can indicate:
+ *      OK - authorised. client and credential are set in rqstp.
+ *           reqbuf points to arguments
+ *           resbuf points to good place for results.  verfier
+ *             is (probably) already in place.  Certainly space is
+ *	       reserved for it.
+ *      DROP - simply drop the request. It may have been deferred
+ *      GARBAGE - rpc garbage_args error
+ *      SYSERR - rpc system_err error
+ *      DENIED - authp holds reason for denial.
+ *      COMPLETE - the reply is encoded already and ready to be sent; no
+ *		further processing is necessary.  (This is used for processing
+ *		null procedure calls which are used to set up encryption
+ *		contexts.)
+ *
+ *   accept is passed the proc number so that it can accept NULL rpc requests
+ *   even if it cannot authenticate the client (as is sometimes appropriate).
+ *
+ * release() is given a request after the procedure has been run.
+ *  It should sign/encrypt the results if needed
+ * It should return:
+ *    OK - the resbuf is ready to be sent
+ *    DROP - the reply should be quitely dropped
+ *    DENIED - authp holds a reason for MSG_DENIED
+ *    SYSERR - rpc system_err
+ *
+ * domain_release()
+ *   This call releases a domain.
+ * set_client()
+ *   Givens a pending request (struct svc_rqst), finds and assigns
+ *   an appropriate 'auth_domain' as the client.
+ */
+struct auth_ops {
+	char *	name;
+	struct module *owner;
+	int	flavour;
+	int	(*accept)(struct svc_rqst *rq, __be32 *authp);
+	int	(*release)(struct svc_rqst *rq);
+	void	(*domain_release)(struct auth_domain *);
+	int	(*set_client)(struct svc_rqst *rq);
+};
+
+#define	SVC_GARBAGE	1
+#define	SVC_SYSERR	2
+#define	SVC_VALID	3
+#define	SVC_NEGATIVE	4
+#define	SVC_OK		5
+#define	SVC_DROP	6
+#define	SVC_CLOSE	7	/* Like SVC_DROP, but request is definitely
+				 * lost so if there is a tcp connection, it
+				 * should be closed
+				 */
+#define	SVC_DENIED	8
+#define	SVC_PENDING	9
+#define	SVC_COMPLETE	10
+
+struct svc_xprt;
+
+extern int	svc_authenticate(struct svc_rqst *rqstp, __be32 *authp);
+extern int	svc_authorise(struct svc_rqst *rqstp);
+extern int	svc_set_client(struct svc_rqst *rqstp);
+extern int	svc_auth_register(rpc_authflavor_t flavor, struct auth_ops *aops);
+extern void	svc_auth_unregister(rpc_authflavor_t flavor);
+
+extern struct auth_domain *unix_domain_find(char *name);
+extern void auth_domain_put(struct auth_domain *item);
+extern int auth_unix_add_addr(struct net *net, struct in6_addr *addr, struct auth_domain *dom);
+extern struct auth_domain *auth_domain_lookup(char *name, struct auth_domain *new);
+extern struct auth_domain *auth_domain_find(char *name);
+extern struct auth_domain *auth_unix_lookup(struct net *net, struct in6_addr *addr);
+extern int auth_unix_forget_old(struct auth_domain *dom);
+extern void svcauth_unix_purge(struct net *net);
+extern void svcauth_unix_info_release(struct svc_xprt *xpt);
+extern int svcauth_unix_set_client(struct svc_rqst *rqstp);
+
+extern int unix_gid_cache_create(struct net *net);
+extern void unix_gid_cache_destroy(struct net *net);
+
+/*
+ * The <stringhash.h> functions are good enough that we don't need to
+ * use hash_32() on them; just extracting the high bits is enough.
+ */
+static inline unsigned long hash_str(char const *name, int bits)
+{
+	return hashlen_hash(hashlen_string(NULL, name)) >> (32 - bits);
+}
+
+static inline unsigned long hash_mem(char const *buf, int length, int bits)
+{
+	return full_name_hash(NULL, buf, length) >> (32 - bits);
+}
+
+#endif /* __KERNEL__ */
+
+#endif /* _LINUX_SUNRPC_SVCAUTH_H_ */