SUNRPC: Cache cred of process creating the rpc_client

When converting kuids to AUTH_UNIX creds, etc we will want to use the
same user namespace as the process that created the rpc client.

Signed-off-by: Trond Myklebust <[e-mail]>
Signed-off-by: Anna Schumaker <[e-mail]>

fs/lockd/host.c

···
 			.authflavor	= RPC_AUTH_UNIX,
 			.flags		= (RPC_CLNT_CREATE_NOPING |
 					   RPC_CLNT_CREATE_AUTOBIND),
+			.cred		= current_cred(),
 		};
 
 		/*

fs/lockd/mon.c

···
 		.version		= NSM_VERSION,
 		.authflavor		= RPC_AUTH_NULL,
 		.flags			= RPC_CLNT_CREATE_NOPING,
+		.cred			= current_cred(),
 	};
 
 	return rpc_create(&args);

fs/nfs/client.c

···
 		.program	= &nfs_program,
 		.version	= clp->rpc_ops->version,
 		.authflavor	= flavor,
+		.cred		= current_cred(),
 	};
 
 	if (test_bit(NFS_CS_DISCRTRY, &clp->cl_flags))

fs/nfs/mount_clnt.c

···
 		.program	= &mnt_program,
 		.version	= info->version,
 		.authflavor	= RPC_AUTH_UNIX,
+		.cred		= current_cred(),
 	};
 	struct rpc_clnt		*mnt_clnt;
 	int			status;
···
 		.version	= info->version,
 		.authflavor	= RPC_AUTH_UNIX,
 		.flags		= RPC_CLNT_CREATE_NOPING,
+		.cred		= current_cred(),
 	};
 	struct rpc_message msg	= {
 		.rpc_argp	= info->dirpath,

fs/nfsd/nfs4callback.c

···
 		.program	= &cb_program,
 		.version	= 1,
 		.flags		= (RPC_CLNT_CREATE_NOPING | RPC_CLNT_CREATE_QUIET),
+		.cred		= current_cred(),
 	};
 	struct rpc_clnt *client;
 	const struct cred *cred;

include/linux/sunrpc/clnt.h

···
 	struct dentry		*cl_debugfs;	/* debugfs directory */
 #endif
 	struct rpc_xprt_iter	cl_xpi;
+	const struct cred	*cl_cred;
 };
 
 /*
···
 	unsigned long		flags;
 	char			*client_name;
 	struct svc_xprt		*bc_xprt;	/* NFSv4.1 backchannel */
+	const struct cred	*cred;
 };
 
 struct rpc_add_xprt_test {

net/sunrpc/clnt.c

···
 	if (err)
 		goto out_no_clid;
 
+	clnt->cl_cred	  = get_cred(args->cred);
 	clnt->cl_procinfo = version->procs;
 	clnt->cl_maxproc  = version->nrprocs;
 	clnt->cl_prog     = args->prognumber ? : program->number;
···
 out_no_path:
 	rpc_free_iostats(clnt->cl_metrics);
 out_no_stats:
+	put_cred(clnt->cl_cred);
 	rpc_free_clid(clnt);
 out_no_clid:
 	kfree(clnt);
···
 	new->cl_discrtry = clnt->cl_discrtry;
 	new->cl_chatty = clnt->cl_chatty;
 	new->cl_principal = clnt->cl_principal;
+	new->cl_cred = get_cred(clnt->cl_cred);
 	return new;
 
 out_err:
···
 		.prognumber	= clnt->cl_prog,
 		.version	= clnt->cl_vers,
 		.authflavor	= clnt->cl_auth->au_flavor,
+		.cred		= clnt->cl_cred,
 	};
 	return __rpc_clone_client(&args, clnt);
 }
···
 		.prognumber	= clnt->cl_prog,
 		.version	= clnt->cl_vers,
 		.authflavor	= flavor,
+		.cred		= clnt->cl_cred,
 	};
 	return __rpc_clone_client(&args, clnt);
 }
···
 	xprt_put(rcu_dereference_raw(clnt->cl_xprt));
 	xprt_iter_destroy(&clnt->cl_xpi);
 	rpciod_down();
+	put_cred(clnt->cl_cred);
 	rpc_free_clid(clnt);
 	kfree(clnt);
 	return parent;
···
 		.prognumber	= program->number,
 		.version	= vers,
 		.authflavor	= old->cl_auth->au_flavor,
+		.cred		= old->cl_cred,
 	};
 	struct rpc_clnt *clnt;
 	int err;

net/sunrpc/rpcb_clnt.c

···
 		.program	= &rpcb_program,
 		.version	= RPCBVERS_2,
 		.authflavor	= RPC_AUTH_NULL,
+		.cred		= current_cred(),
 		/*
 		 * We turn off the idle timeout to prevent the kernel
 		 * from automatically disconnecting the socket.
···
 		.program	= &rpcb_program,
 		.version	= RPCBVERS_2,
 		.authflavor	= RPC_AUTH_UNIX,
+		.cred		= current_cred(),
 		.flags		= RPC_CLNT_CREATE_NOPING,
 	};
 	struct rpc_clnt *clnt, *clnt4;
···
 static struct rpc_clnt *rpcb_create(struct net *net, const char *nodename,
 				    const char *hostname,
 				    struct sockaddr *srvaddr, size_t salen,
-				    int proto, u32 version)
+				    int proto, u32 version,
+				    const struct cred *cred)
 {
 	struct rpc_create_args args = {
 		.net		= net,
···
 		.program	= &rpcb_program,
 		.version	= version,
 		.authflavor	= RPC_AUTH_UNIX,
+		.cred		= cred,
 		.flags		= (RPC_CLNT_CREATE_NOPING |
 					RPC_CLNT_CREATE_NONPRIVPORT),
 	};
···
 	rpcb_clnt = rpcb_create(xprt->xprt_net,
 				clnt->cl_nodename,
 				xprt->servername, sap, salen,
-				xprt->prot, bind_version);
+				xprt->prot, bind_version,
+				clnt->cl_cred);
 	if (IS_ERR(rpcb_clnt)) {
 		status = PTR_ERR(rpcb_clnt);
 		dprintk("RPC: %5u %s: rpcb_create failed, error %ld\n",