1 files changed, 429 insertions, 0 deletions
diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
new file mode 100644
index 000000000..456af7d23
--- /dev/null
+++ b/fs/nfs/callback.c
@@ -0,0 +1,429 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/fs/nfs/callback.c
+ *
+ * Copyright (C) 2004 Trond Myklebust
+ *
+ * NFSv4 callback handling
+ */
+
+#include <linux/completion.h>
+#include <linux/ip.h>
+#include <linux/module.h>
+#include <linux/sched/signal.h>
+#include <linux/sunrpc/svc.h>
+#include <linux/sunrpc/svcsock.h>
+#include <linux/nfs_fs.h>
+#include <linux/errno.h>
+#include <linux/mutex.h>
+#include <linux/freezer.h>
+#include <linux/sunrpc/svcauth_gss.h>
+#include <linux/sunrpc/bc_xprt.h>
+
+#include <net/inet_sock.h>
+
+#include "nfs4_fs.h"
+#include "callback.h"
+#include "internal.h"
+#include "netns.h"
+
+#define NFSDBG_FACILITY NFSDBG_CALLBACK
+
+struct nfs_callback_data {
+	unsigned int users;
+	struct svc_serv *serv;
+};
+
+static struct nfs_callback_data nfs_callback_info[NFS4_MAX_MINOR_VERSION + 1];
+static DEFINE_MUTEX(nfs_callback_mutex);
+static struct svc_program nfs4_callback_program;
+
+static int nfs4_callback_up_net(struct svc_serv *serv, struct net *net)
+{
+	const struct cred *cred = current_cred();
+	int ret;
+	struct nfs_net *nn = net_generic(net, nfs_net_id);
+
+	ret = svc_xprt_create(serv, "tcp", net, PF_INET,
+			      nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS,
+			      cred);
+	if (ret <= 0)
+		goto out_err;
+	nn->nfs_callback_tcpport = ret;
+	dprintk("NFS: Callback listener port = %u (af %u, net %x)\n",
+		nn->nfs_callback_tcpport, PF_INET, net->ns.inum);
+
+	ret = svc_xprt_create(serv, "tcp", net, PF_INET6,
+			      nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS,
+			      cred);
+	if (ret > 0) {
+		nn->nfs_callback_tcpport6 = ret;
+		dprintk("NFS: Callback listener port = %u (af %u, net %x)\n",
+			nn->nfs_callback_tcpport6, PF_INET6, net->ns.inum);
+	} else if (ret != -EAFNOSUPPORT)
+		goto out_err;
+	return 0;
+
+out_err:
+	return (ret) ? ret : -ENOMEM;
+}
+
+/*
+ * This is the NFSv4 callback kernel thread.
+ */
+static int
+nfs4_callback_svc(void *vrqstp)
+{
+	int err;
+	struct svc_rqst *rqstp = vrqstp;
+
+	set_freezable();
+
+	while (!kthread_freezable_should_stop(NULL)) {
+
+		if (signal_pending(current))
+			flush_signals(current);
+		/*
+		 * Listen for a request on the socket
+		 */
+		err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
+		if (err == -EAGAIN || err == -EINTR)
+			continue;
+		svc_process(rqstp);
+	}
+
+	svc_exit_thread(rqstp);
+	return 0;
+}
+
+#if defined(CONFIG_NFS_V4_1)
+/*
+ * The callback service for NFSv4.1 callbacks
+ */
+static int
+nfs41_callback_svc(void *vrqstp)
+{
+	struct svc_rqst *rqstp = vrqstp;
+	struct svc_serv *serv = rqstp->rq_server;
+	struct rpc_rqst *req;
+	int error;
+	DEFINE_WAIT(wq);
+
+	set_freezable();
+
+	while (!kthread_freezable_should_stop(NULL)) {
+
+		if (signal_pending(current))
+			flush_signals(current);
+
+		prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE);
+		spin_lock_bh(&serv->sv_cb_lock);
+		if (!list_empty(&serv->sv_cb_list)) {
+			req = list_first_entry(&serv->sv_cb_list,
+					struct rpc_rqst, rq_bc_list);
+			list_del(&req->rq_bc_list);
+			spin_unlock_bh(&serv->sv_cb_lock);
+			finish_wait(&serv->sv_cb_waitq, &wq);
+			dprintk("Invoking bc_svc_process()\n");
+			error = bc_svc_process(serv, req, rqstp);
+			dprintk("bc_svc_process() returned w/ error code= %d\n",
+				error);
+		} else {
+			spin_unlock_bh(&serv->sv_cb_lock);
+			if (!kthread_should_stop())
+				schedule();
+			finish_wait(&serv->sv_cb_waitq, &wq);
+		}
+	}
+
+	svc_exit_thread(rqstp);
+	return 0;
+}
+
+static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
+		struct svc_serv *serv)
+{
+	if (minorversion)
+		/*
+		 * Save the svc_serv in the transport so that it can
+		 * be referenced when the session backchannel is initialized
+		 */
+		xprt->bc_serv = serv;
+}
+#else
+static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
+		struct svc_serv *serv)
+{
+}
+#endif /* CONFIG_NFS_V4_1 */
+
+static int nfs_callback_start_svc(int minorversion, struct rpc_xprt *xprt,
+				  struct svc_serv *serv)
+{
+	int nrservs = nfs_callback_nr_threads;
+	int ret;
+
+	nfs_callback_bc_serv(minorversion, xprt, serv);
+
+	if (nrservs < NFS4_MIN_NR_CALLBACK_THREADS)
+		nrservs = NFS4_MIN_NR_CALLBACK_THREADS;
+
+	if (serv->sv_nrthreads == nrservs)
+		return 0;
+
+	ret = svc_set_num_threads(serv, NULL, nrservs);
+	if (ret) {
+		svc_set_num_threads(serv, NULL, 0);
+		return ret;
+	}
+	dprintk("nfs_callback_up: service started\n");
+	return 0;
+}
+
+static void nfs_callback_down_net(u32 minorversion, struct svc_serv *serv, struct net *net)
+{
+	struct nfs_net *nn = net_generic(net, nfs_net_id);
+
+	if (--nn->cb_users[minorversion])
+		return;
+
+	dprintk("NFS: destroy per-net callback data; net=%x\n", net->ns.inum);
+	svc_xprt_destroy_all(serv, net);
+}
+
+static int nfs_callback_up_net(int minorversion, struct svc_serv *serv,
+			       struct net *net, struct rpc_xprt *xprt)
+{
+	struct nfs_net *nn = net_generic(net, nfs_net_id);
+	int ret;
+
+	if (nn->cb_users[minorversion]++)
+		return 0;
+
+	dprintk("NFS: create per-net callback data; net=%x\n", net->ns.inum);
+
+	ret = svc_bind(serv, net);
+	if (ret < 0) {
+		printk(KERN_WARNING "NFS: bind callback service failed\n");
+		goto err_bind;
+	}
+
+	ret = 0;
+	if (!IS_ENABLED(CONFIG_NFS_V4_1) || minorversion == 0)
+		ret = nfs4_callback_up_net(serv, net);
+	else if (xprt->ops->bc_setup)
+		set_bc_enabled(serv);
+	else
+		ret = -EPROTONOSUPPORT;
+
+	if (ret < 0) {
+		printk(KERN_ERR "NFS: callback service start failed\n");
+		goto err_socks;
+	}
+	return 0;
+
+err_socks:
+	svc_rpcb_cleanup(serv, net);
+err_bind:
+	nn->cb_users[minorversion]--;
+	dprintk("NFS: Couldn't create callback socket: err = %d; "
+			"net = %x\n", ret, net->ns.inum);
+	return ret;
+}
+
+static struct svc_serv *nfs_callback_create_svc(int minorversion)
+{
+	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
+	int (*threadfn)(void *data);
+	struct svc_serv *serv;
+
+	/*
+	 * Check whether we're already up and running.
+	 */
+	if (cb_info->serv)
+		return svc_get(cb_info->serv);
+
+	/*
+	 * Sanity check: if there's no task,
+	 * we should be the first user ...
+	 */
+	if (cb_info->users)
+		printk(KERN_WARNING "nfs_callback_create_svc: no kthread, %d users??\n",
+			cb_info->users);
+
+	threadfn = nfs4_callback_svc;
+#if defined(CONFIG_NFS_V4_1)
+	if (minorversion)
+		threadfn = nfs41_callback_svc;
+#else
+	if (minorversion)
+		return ERR_PTR(-ENOTSUPP);
+#endif
+	serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE,
+			  threadfn);
+	if (!serv) {
+		printk(KERN_ERR "nfs_callback_create_svc: create service failed\n");
+		return ERR_PTR(-ENOMEM);
+	}
+	cb_info->serv = serv;
+	/* As there is only one thread we need to over-ride the
+	 * default maximum of 80 connections
+	 */
+	serv->sv_maxconn = 1024;
+	dprintk("nfs_callback_create_svc: service created\n");
+	return serv;
+}
+
+/*
+ * Bring up the callback thread if it is not already up.
+ */
+int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
+{
+	struct svc_serv *serv;
+	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
+	int ret;
+	struct net *net = xprt->xprt_net;
+
+	mutex_lock(&nfs_callback_mutex);
+
+	serv = nfs_callback_create_svc(minorversion);
+	if (IS_ERR(serv)) {
+		ret = PTR_ERR(serv);
+		goto err_create;
+	}
+
+	ret = nfs_callback_up_net(minorversion, serv, net, xprt);
+	if (ret < 0)
+		goto err_net;
+
+	ret = nfs_callback_start_svc(minorversion, xprt, serv);
+	if (ret < 0)
+		goto err_start;
+
+	cb_info->users++;
+err_net:
+	if (!cb_info->users)
+		cb_info->serv = NULL;
+	svc_put(serv);
+err_create:
+	mutex_unlock(&nfs_callback_mutex);
+	return ret;
+
+err_start:
+	nfs_callback_down_net(minorversion, serv, net);
+	dprintk("NFS: Couldn't create server thread; err = %d\n", ret);
+	goto err_net;
+}
+
+/*
+ * Kill the callback thread if it's no longer being used.
+ */
+void nfs_callback_down(int minorversion, struct net *net)
+{
+	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
+	struct svc_serv *serv;
+
+	mutex_lock(&nfs_callback_mutex);
+	serv = cb_info->serv;
+	nfs_callback_down_net(minorversion, serv, net);
+	cb_info->users--;
+	if (cb_info->users == 0) {
+		svc_get(serv);
+		svc_set_num_threads(serv, NULL, 0);
+		svc_put(serv);
+		dprintk("nfs_callback_down: service destroyed\n");
+		cb_info->serv = NULL;
+	}
+	mutex_unlock(&nfs_callback_mutex);
+}
+
+/* Boolean check of RPC_AUTH_GSS principal */
+int
+check_gss_callback_principal(struct nfs_client *clp, struct svc_rqst *rqstp)
+{
+	char *p = rqstp->rq_cred.cr_principal;
+
+	if (rqstp->rq_authop->flavour != RPC_AUTH_GSS)
+		return 1;
+
+	/* No RPC_AUTH_GSS on NFSv4.1 back channel yet */
+	if (clp->cl_minorversion != 0)
+		return 0;
+	/*
+	 * It might just be a normal user principal, in which case
+	 * userspace won't bother to tell us the name at all.
+	 */
+	if (p == NULL)
+		return 0;
+
+	/*
+	 * Did we get the acceptor from userland during the SETCLIENID
+	 * negotiation?
+	 */
+	if (clp->cl_acceptor)
+		return !strcmp(p, clp->cl_acceptor);
+
+	/*
+	 * Otherwise try to verify it using the cl_hostname. Note that this
+	 * doesn't work if a non-canonical hostname was used in the devname.
+	 */
+
+	/* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
+
+	if (memcmp(p, "nfs@", 4) != 0)
+		return 0;
+	p += 4;
+	if (strcmp(p, clp->cl_hostname) != 0)
+		return 0;
+	return 1;
+}
+
+/*
+ * pg_authenticate method for nfsv4 callback threads.
+ *
+ * The authflavor has been negotiated, so an incorrect flavor is a server
+ * bug. Deny packets with incorrect authflavor.
+ *
+ * All other checking done after NFS decoding where the nfs_client can be
+ * found in nfs4_callback_compound
+ */
+static int nfs_callback_authenticate(struct svc_rqst *rqstp)
+{
+	rqstp->rq_auth_stat = rpc_autherr_badcred;
+
+	switch (rqstp->rq_authop->flavour) {
+	case RPC_AUTH_NULL:
+		if (rqstp->rq_proc != CB_NULL)
+			return SVC_DENIED;
+		break;
+	case RPC_AUTH_GSS:
+		/* No RPC_AUTH_GSS support yet in NFSv4.1 */
+		 if (svc_is_backchannel(rqstp))
+			return SVC_DENIED;
+	}
+
+	rqstp->rq_auth_stat = rpc_auth_ok;
+	return SVC_OK;
+}
+
+/*
+ * Define NFS4 callback program
+ */
+static const struct svc_version *nfs4_callback_version[] = {
+	[1] = &nfs4_callback_version1,
+	[4] = &nfs4_callback_version4,
+};
+
+static struct svc_stat nfs4_callback_stats;
+
+static struct svc_program nfs4_callback_program = {
+	.pg_prog = NFS4_CALLBACK,			/* RPC service number */
+	.pg_nvers = ARRAY_SIZE(nfs4_callback_version),	/* Number of entries */
+	.pg_vers = nfs4_callback_version,		/* version table */
+	.pg_name = "NFSv4 callback",			/* service name */
+	.pg_class = "nfs",				/* authentication class */
+	.pg_stats = &nfs4_callback_stats,
+	.pg_authenticate = nfs_callback_authenticate,
+	.pg_init_request = svc_generic_init_request,
+	.pg_rpcbind_set	= svc_generic_rpcbind_set,
+};