SUNRPC: Add a generic RPC credential

Add an rpc credential that is not tied to any particular auth mechanism,
but that can be cached by NFS, and later used to look up a cred for
whichever auth mechanism that turns out to be valid when the RPC call is
being made.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

include/linux/sunrpc/auth.h

@@ -125,9 +125,12 @@ extern const struct rpc_authops	authunix_ops;
 extern const struct rpc_authops	authnull_ops;
 
 void __init		rpc_init_authunix(void);
+void __init		rpc_init_generic_auth(void);
 void __init		rpcauth_init_module(void);
 void __exit		rpcauth_remove_module(void);
+void __exit		rpc_destroy_generic_auth(void);
 
+struct rpc_cred *	rpc_lookup_cred(void);
 int			rpcauth_register(const struct rpc_authops *);
 int			rpcauth_unregister(const struct rpc_authops *);
 struct rpc_auth *	rpcauth_create(rpc_authflavor_t, struct rpc_clnt *);

net/sunrpc/Makefile

@@ -8,7 +8,7 @@ obj-$(CONFIG_SUNRPC_GSS) += auth_gss/
 obj-$(CONFIG_SUNRPC_XPRT_RDMA) += xprtrdma/
 
 sunrpc-y := clnt.o xprt.o socklib.o xprtsock.o sched.o \
-	    auth.o auth_null.o auth_unix.o \
+	    auth.o auth_null.o auth_unix.o auth_generic.o \
 	    svc.o svcsock.o svcauth.o svcauth_unix.o \
 	    rpcb_clnt.o timer.o xdr.o \
 	    sunrpc_syms.o cache.o rpc_pipe.o \

net/sunrpc/auth.c

@@ -566,6 +566,7 @@ static struct shrinker rpc_cred_shrinker = {
 void __init rpcauth_init_module(void)
 {
 	rpc_init_authunix();
+	rpc_init_generic_auth();
 	register_shrinker(&rpc_cred_shrinker);
 }
 

net/sunrpc/auth_generic.c

+/*
+ * Generic RPC credential
+ *
+ * Copyright (C) 2008, Trond Myklebust <Trond.Myklebust@netapp.com>
+ */
+
+#include <linux/err.h>
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/sunrpc/auth.h>
+#include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/debug.h>
+#include <linux/sunrpc/sched.h>
+
+#ifdef RPC_DEBUG
+# define RPCDBG_FACILITY	RPCDBG_AUTH
+#endif
+
+struct generic_cred {
+	struct rpc_cred gc_base;
+	struct auth_cred acred;
+};
+
+static struct rpc_auth generic_auth;
+static struct rpc_cred_cache generic_cred_cache;
+static const struct rpc_credops generic_credops;
+
+/*
+ * Public call interface
+ */
+struct rpc_cred *rpc_lookup_cred(void)
+{
+	return rpcauth_lookupcred(&generic_auth, 0);
+}
+EXPORT_SYMBOL_GPL(rpc_lookup_cred);
+
+/*
+ * Lookup generic creds for current process
+ */
+static struct rpc_cred *
+generic_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
+{
+	return rpcauth_lookup_credcache(&generic_auth, acred, flags);
+}
+
+static struct rpc_cred *
+generic_create_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
+{
+	struct generic_cred *gcred;
+
+	gcred = kmalloc(sizeof(*gcred), GFP_KERNEL);
+	if (gcred == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	rpcauth_init_cred(&gcred->gc_base, acred, &generic_auth, &generic_credops);
+	gcred->gc_base.cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
+
+	gcred->acred.uid = acred->uid;
+	gcred->acred.gid = acred->gid;
+	gcred->acred.group_info = acred->group_info;
+	if (gcred->acred.group_info != NULL)
+		get_group_info(gcred->acred.group_info);
+
+	dprintk("RPC:       allocated generic cred %p for uid %d gid %d\n",
+			gcred, acred->uid, acred->gid);
+	return &gcred->gc_base;
+}
+
+static void
+generic_free_cred(struct rpc_cred *cred)
+{
+	struct generic_cred *gcred = container_of(cred, struct generic_cred, gc_base);
+
+	dprintk("RPC:       generic_free_cred %p\n", gcred);
+	if (gcred->acred.group_info != NULL)
+		put_group_info(gcred->acred.group_info);
+	kfree(gcred);
+}
+
+static void
+generic_free_cred_callback(struct rcu_head *head)
+{
+	struct rpc_cred *cred = container_of(head, struct rpc_cred, cr_rcu);
+	generic_free_cred(cred);
+}
+
+static void
+generic_destroy_cred(struct rpc_cred *cred)
+{
+	call_rcu(&cred->cr_rcu, generic_free_cred_callback);
+}
+
+/*
+ * Match credentials against current process creds.
+ */
+static int
+generic_match(struct auth_cred *acred, struct rpc_cred *cred, int flags)
+{
+	struct generic_cred *gcred = container_of(cred, struct generic_cred, gc_base);
+
+	if (gcred->acred.uid != acred->uid ||
+	    gcred->acred.gid != acred->gid ||
+	    gcred->acred.group_info != acred->group_info)
+		return 0;
+	return 1;
+}
+
+void __init rpc_init_generic_auth(void)
+{
+	spin_lock_init(&generic_cred_cache.lock);
+}
+
+void __exit rpc_destroy_generic_auth(void)
+{
+	rpcauth_clear_credcache(&generic_cred_cache);
+}
+
+static struct rpc_cred_cache generic_cred_cache = {
+	{{ NULL, },},
+};
+
+static const struct rpc_authops generic_auth_ops = {
+	.owner = THIS_MODULE,
+#ifdef RPC_DEBUG
+	.au_name = "Generic",
+#endif
+	.lookup_cred = generic_lookup_cred,
+	.crcreate = generic_create_cred,
+};
+
+static struct rpc_auth generic_auth = {
+	.au_ops = &generic_auth_ops,
+	.au_count = ATOMIC_INIT(0),
+	.au_credcache = &generic_cred_cache,
+};
+
+static const struct rpc_credops generic_credops = {
+	.cr_name = "Generic cred",
+	.crdestroy = generic_destroy_cred,
+	.crmatch = generic_match,
+};