path: root/net/sunrpc/rpc_pipe.c

/*
 * net/sunrpc/rpc_pipe.c
 *
 * Userland/kernel interface for rpcauth_gss.
 * Code shamelessly plagiarized from fs/nfsd/nfsctl.c
 * and fs/sysfs/inode.c
 *
 * Copyright (c) 2002, Trond Myklebust <trond.myklebust@fys.uio.no>
 *
 */
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/pagemap.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/fsnotify.h>
#include <linux/kernel.h>
#include <linux/rcupdate.h>
#include <linux/utsname.h>

#include <asm/ioctls.h>
#include <linux/poll.h>
#include <linux/wait.h>
#include <linux/seq_file.h>

#include <linux/sunrpc/clnt.h>
#include <linux/workqueue.h>
#include <linux/sunrpc/rpc_pipe_fs.h>
#include <linux/sunrpc/cache.h>
#include <linux/nsproxy.h>
#include <linux/notifier.h>

#include "netns.h"
#include "sunrpc.h"

#define RPCDBG_FACILITY RPCDBG_DEBUG

#define NET_NAME(net)	((net == &init_net) ? " (init_net)" : "")

static struct file_system_type rpc_pipe_fs_type;
static const struct rpc_pipe_ops gssd_dummy_pipe_ops;

static struct kmem_cache *rpc_inode_cachep __read_mostly;

#define RPC_UPCALL_TIMEOUT (30*HZ)

static BLOCKING_NOTIFIER_HEAD(rpc_pipefs_notifier_list);

int rpc_pipefs_notifier_register(struct notifier_block *nb)
{
	return blocking_notifier_chain_cond_register(&rpc_pipefs_notifier_list, nb);
}
EXPORT_SYMBOL_GPL(rpc_pipefs_notifier_register);

void rpc_pipefs_notifier_unregister(struct notifier_block *nb)
{
	blocking_notifier_chain_unregister(&rpc_pipefs_notifier_list, nb);
}
EXPORT_SYMBOL_GPL(rpc_pipefs_notifier_unregister);

static void rpc_purge_list(wait_queue_head_t *waitq, struct list_head *head,
		void (*destroy_msg)(struct rpc_pipe_msg *), int err)
{
	struct rpc_pipe_msg *msg;

	if (list_empty(head))
		return;
	do {
		msg = list_entry(head->next, struct rpc_pipe_msg, list);
		list_del_init(&msg->list);
		msg->errno = err;
		destroy_msg(msg);
	} while (!list_empty(head));

	if (waitq)
		wake_up(waitq);
}

static void
rpc_timeout_upcall_queue(struct work_struct *work)
{
	LIST_HEAD(free_list);
	struct rpc_pipe *pipe =
		container_of(work, struct rpc_pipe, queue_timeout.work);
	void (*destroy_msg)(struct rpc_pipe_msg *);
	struct dentry *dentry;

	spin_lock(&pipe->lock);
	destroy_msg = pipe->ops->destroy_msg;
	if (pipe->nreaders == 0) {
		list_splice_init(&pipe->pipe, &free_list);
		pipe->pipelen = 0;
	}
	dentry = dget(pipe->dentry);
	spin_unlock(&pipe->lock);
	rpc_purge_list(dentry ? &RPC_I(d_inode(dentry))->waitq : NULL,
			&free_list, destroy_msg, -ETIMEDOUT);
	dput(dentry);
}

ssize_t rpc_pipe_generic_upcall(struct file *filp, struct rpc_pipe_msg *msg,
				char __user *dst, size_t buflen)
{
	char *data = (char *)msg->data + msg->copied;
	size_t mlen = min(msg->len - msg->copied, buflen);
	unsigned long left;

	left = copy_to_user(dst, data, mlen);
	if (left == mlen) {
		msg->errno = -EFAULT;
		return -EFAULT;
	}

	mlen -= left;
	msg->copied += mlen;
	msg->errno = 0;
	return mlen;
}
EXPORT_SYMBOL_GPL(rpc_pipe_generic_upcall);

/**
 * rpc_queue_upcall - queue an upcall message to userspace
 * @pipe: upcall pipe on which to queue given message
 * @msg: message to queue
 *
 * Call with an @inode created by rpc_mkpipe() to queue an upcall.
 * A userspace process may then later read the upcall by performing a
 * read on an open file for this inode.  It is up to the caller to
 * initialize the fields of @msg (other than @msg->list) appropriately.
 */
int
rpc_queue_upcall(struct rpc_pipe *pipe, struct rpc_pipe_msg *msg)
{
	int res = -EPIPE;
	struct dentry *dentry;

	spin_lock(&pipe->lock);
	if (pipe->nreaders) {
		list_add_tail(&msg->list, &pipe->pipe);
		pipe->pipelen += msg->len;
		res = 0;
	} else if (pipe->flags & RPC_PIPE_WAIT_FOR_OPEN) {
		if (list_empty(&pipe->pipe))
			queue_delayed_work(rpciod_workqueue,
					&pipe->queue_timeout,
					RPC_UPCALL_TIMEOUT);
		list_add_tail(&msg->list, &pipe->pipe);
		pipe->pipelen += msg->len;
		res = 0;
	}
	dentry = dget(pipe->dentry);
	spin_unlock(&pipe->lock);
	if (dentry) {
		wake_up(&RPC_I(d_inode(dentry))->waitq);
		dput(dentry);
	}
	return res;
}
EXPORT_SYMBOL_GPL(rpc_queue_upcall);

static inline void
rpc_inode_setowner(struct inode *inode, void *private)
{
	RPC_I(inode)->private = private;
}

static void
rpc_close_pipes(struct inode *inode)
{
	struct rpc_pipe *pipe = RPC_I(inode)->pipe;
	int need_release;
	LIST_HEAD(free_list);

	inode_lock(inode);
	spin_lock(&pipe->lock);
	need_release = pipe->nreaders != 0 || pipe->nwriters != 0;
	pipe->nreaders = 0;
	list_splice_init(&pipe->in_upcall, &free_list);
	list_splice_init(&pipe->pipe, &free_list);
	pipe->pipelen = 0;
	pipe->dentry = NULL;
	spin_unlock(&pipe->lock);
	rpc_purge_list(&RPC_I(inode)->waitq, &free_list, pipe->ops->destroy_msg, -EPIPE);
	pipe->nwriters = 0;
	if (need_release && pipe->ops->release_pipe)
		pipe->ops->release_pipe(inode);
	cancel_delayed_work_sync(&pipe->queue_timeout);
	rpc_inode_setowner(inode, NULL);
	RPC_I(inode)->pipe = NULL;
	inode_unlock(inode);
}

static struct inode *
rpc_alloc_inode(struct super_block *sb)
{
	struct rpc_inode *rpci;
	rpci = kmem_cache_alloc(rpc_inode_cachep, GFP_KERNEL);
	if (!rpci)
		return NULL;
	return &rpci->vfs_inode;
}

static void
rpc_i_callback(struct rcu_head *head)
{
	struct inode *inode = container_of(head, struct inode, i_rcu);
	kmem_cache_free(rpc_inode_cachep, RPC_I(inode));
}

static void
rpc_destroy_inode(struct inode *inode)
{
	call_rcu(&inode->i_rcu, rpc_i_callback);
}

static int
rpc_pipe_open(struct inode *inode, struct file *filp)
{
	struct rpc_pipe *pipe;
	int first_open;
	int res = -ENXIO;

	inode_lock(inode);
	pipe = RPC_I(inode)->pipe;
	if (pipe == NULL)
		goto out;
	first_open = pipe->nreaders == 0 && pipe->nwriters == 0;
	if (first_open && pipe->ops->open_pipe) {
		res = pipe->ops->open_pipe(inode);
		if (res)
			goto out;
	}
	if (filp->f_mode & FMODE_READ)
		pipe->nreaders++;
	if (filp->f_mode & FMODE_WRITE)
		pipe->nwriters++;
	res = 0;
out:
	inode_unlock(inode);
	return res;
}

static int
rpc_pipe_release(struct inode *inode, struct file *filp)
{
	struct rpc_pipe *pipe;
	struct rpc_pipe_msg *msg;
	int last_close;

	inode_lock(inode);
	pipe = RPC_I(inode)->pipe;
	if (pipe == NULL)
		goto out;
	msg = filp->private_data;
	if (msg != NULL) {
		spin_lock(&pipe->lock);
		msg->errno = -EAGAIN;
		list_del_init(&msg->list);
		spin_unlock(&pipe->lock);
		pipe->ops->destroy_msg(msg);
	}
	if (filp->f_mode & FMODE_WRITE)
		pipe->nwriters --;
	if (filp->f_mode & FMODE_READ) {
		pipe->nreaders --;
		if (pipe->nreaders == 0) {
			LIST_HEAD(free_list);
			spin_lock(&pipe->lock);
			list_splice_init(&pipe->pipe, &free_list);
			pipe->pipelen = 0;
			spin_unlock(&pipe->lock);
			rpc_purge_list(&RPC_I(inode)->waitq, &free_list,
					pipe->ops->destroy_msg, -EAGAIN);
		}
	}
	last_close = pipe->nwriters == 0 && pipe->nreaders == 0;
	if (last_close && pipe->ops->release_pipe)
		pipe->ops->release_pipe(inode);
out:
	inode_unlock(inode);
	return 0;
}

static ssize_t
rpc_pipe_read(struct file *filp, char __user *buf, size_t len, loff_t *offset)
{
	struct inode *inode = file_inode(filp);
	struct rpc_pipe *pipe;
	struct rpc_pipe_msg *msg;
	int r