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![zhengbin](/assets/img/avatar_default.png)
Fixes coccicheck warning: fs/fuse/readdir.c:335:1-19: WARNING: Assignment of 0/1 to bool variable fs/fuse/file.c:1398:2-19: WARNING: Assignment of 0/1 to bool variable fs/fuse/file.c:1400:2-20: WARNING: Assignment of 0/1 to bool variable fs/fuse/cuse.c:454:1-20: WARNING: Assignment of 0/1 to bool variable fs/fuse/cuse.c:455:1-19: WARNING: Assignment of 0/1 to bool variable fs/fuse/inode.c:497:2-17: WARNING: Assignment of 0/1 to bool variable fs/fuse/inode.c:504:2-23: WARNING: Assignment of 0/1 to bool variable fs/fuse/inode.c:511:2-22: WARNING: Assignment of 0/1 to bool variable fs/fuse/inode.c:518:2-23: WARNING: Assignment of 0/1 to bool variable fs/fuse/inode.c:522:2-26: WARNING: Assignment of 0/1 to bool variable fs/fuse/inode.c:526:2-18: WARNING: Assignment of 0/1 to bool variable fs/fuse/inode.c:1000:1-20: WARNING: Assignment of 0/1 to bool variable Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: zhengbin <zhengbin13@huawei.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
654 lines
16 KiB
C
654 lines
16 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* CUSE: Character device in Userspace
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*
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* Copyright (C) 2008-2009 SUSE Linux Products GmbH
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* Copyright (C) 2008-2009 Tejun Heo <tj@kernel.org>
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*
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* CUSE enables character devices to be implemented from userland much
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* like FUSE allows filesystems. On initialization /dev/cuse is
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* created. By opening the file and replying to the CUSE_INIT request
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* userland CUSE server can create a character device. After that the
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* operation is very similar to FUSE.
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*
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* A CUSE instance involves the following objects.
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*
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* cuse_conn : contains fuse_conn and serves as bonding structure
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* channel : file handle connected to the userland CUSE server
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* cdev : the implemented character device
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* dev : generic device for cdev
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*
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* Note that 'channel' is what 'dev' is in FUSE. As CUSE deals with
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* devices, it's called 'channel' to reduce confusion.
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*
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* channel determines when the character device dies. When channel is
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* closed, everything begins to destruct. The cuse_conn is taken off
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* the lookup table preventing further access from cdev, cdev and
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* generic device are removed and the base reference of cuse_conn is
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* put.
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*
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* On each open, the matching cuse_conn is looked up and if found an
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* additional reference is taken which is released when the file is
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* closed.
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*/
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#define pr_fmt(fmt) "CUSE: " fmt
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#include <linux/fuse.h>
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#include <linux/cdev.h>
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#include <linux/device.h>
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#include <linux/file.h>
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#include <linux/fs.h>
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#include <linux/kdev_t.h>
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#include <linux/kthread.h>
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#include <linux/list.h>
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#include <linux/magic.h>
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#include <linux/miscdevice.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/stat.h>
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#include <linux/module.h>
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#include <linux/uio.h>
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#include <linux/user_namespace.h>
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#include "fuse_i.h"
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#define CUSE_CONNTBL_LEN 64
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struct cuse_conn {
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struct list_head list; /* linked on cuse_conntbl */
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struct fuse_conn fc; /* fuse connection */
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struct cdev *cdev; /* associated character device */
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struct device *dev; /* device representing @cdev */
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/* init parameters, set once during initialization */
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bool unrestricted_ioctl;
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};
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static DEFINE_MUTEX(cuse_lock); /* protects registration */
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static struct list_head cuse_conntbl[CUSE_CONNTBL_LEN];
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static struct class *cuse_class;
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static struct cuse_conn *fc_to_cc(struct fuse_conn *fc)
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{
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return container_of(fc, struct cuse_conn, fc);
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}
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static struct list_head *cuse_conntbl_head(dev_t devt)
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{
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return &cuse_conntbl[(MAJOR(devt) + MINOR(devt)) % CUSE_CONNTBL_LEN];
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}
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/**************************************************************************
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* CUSE frontend operations
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*
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* These are file operations for the character device.
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*
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* On open, CUSE opens a file from the FUSE mnt and stores it to
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* private_data of the open file. All other ops call FUSE ops on the
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* FUSE file.
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*/
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static ssize_t cuse_read_iter(struct kiocb *kiocb, struct iov_iter *to)
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{
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struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(kiocb);
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loff_t pos = 0;
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return fuse_direct_io(&io, to, &pos, FUSE_DIO_CUSE);
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}
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static ssize_t cuse_write_iter(struct kiocb *kiocb, struct iov_iter *from)
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{
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struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(kiocb);
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loff_t pos = 0;
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/*
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* No locking or generic_write_checks(), the server is
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* responsible for locking and sanity checks.
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*/
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return fuse_direct_io(&io, from, &pos,
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FUSE_DIO_WRITE | FUSE_DIO_CUSE);
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}
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static int cuse_open(struct inode *inode, struct file *file)
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{
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dev_t devt = inode->i_cdev->dev;
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struct cuse_conn *cc = NULL, *pos;
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int rc;
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/* look up and get the connection */
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mutex_lock(&cuse_lock);
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list_for_each_entry(pos, cuse_conntbl_head(devt), list)
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if (pos->dev->devt == devt) {
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fuse_conn_get(&pos->fc);
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cc = pos;
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break;
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}
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mutex_unlock(&cuse_lock);
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/* dead? */
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if (!cc)
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return -ENODEV;
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/*
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* Generic permission check is already done against the chrdev
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* file, proceed to open.
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*/
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rc = fuse_do_open(&cc->fc, 0, file, 0);
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if (rc)
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fuse_conn_put(&cc->fc);
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return rc;
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}
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static int cuse_release(struct inode *inode, struct file *file)
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{
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struct fuse_file *ff = file->private_data;
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struct fuse_conn *fc = ff->fc;
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fuse_sync_release(NULL, ff, file->f_flags);
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fuse_conn_put(fc);
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return 0;
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}
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static long cuse_file_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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struct fuse_file *ff = file->private_data;
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struct cuse_conn *cc = fc_to_cc(ff->fc);
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unsigned int flags = 0;
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if (cc->unrestricted_ioctl)
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flags |= FUSE_IOCTL_UNRESTRICTED;
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return fuse_do_ioctl(file, cmd, arg, flags);
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}
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static long cuse_file_compat_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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struct fuse_file *ff = file->private_data;
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struct cuse_conn *cc = fc_to_cc(ff->fc);
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unsigned int flags = FUSE_IOCTL_COMPAT;
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if (cc->unrestricted_ioctl)
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flags |= FUSE_IOCTL_UNRESTRICTED;
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return fuse_do_ioctl(file, cmd, arg, flags);
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}
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static const struct file_operations cuse_frontend_fops = {
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.owner = THIS_MODULE,
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.read_iter = cuse_read_iter,
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.write_iter = cuse_write_iter,
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.open = cuse_open,
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.release = cuse_release,
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.unlocked_ioctl = cuse_file_ioctl,
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.compat_ioctl = cuse_file_compat_ioctl,
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.poll = fuse_file_poll,
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.llseek = noop_llseek,
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};
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/**************************************************************************
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* CUSE channel initialization and destruction
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*/
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struct cuse_devinfo {
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const char *name;
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};
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/**
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* cuse_parse_one - parse one key=value pair
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* @pp: i/o parameter for the current position
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* @end: points to one past the end of the packed string
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* @keyp: out parameter for key
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* @valp: out parameter for value
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*
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* *@pp points to packed strings - "key0=val0\0key1=val1\0" which ends
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* at @end - 1. This function parses one pair and set *@keyp to the
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* start of the key and *@valp to the start of the value. Note that
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* the original string is modified such that the key string is
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* terminated with '\0'. *@pp is updated to point to the next string.
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*
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* RETURNS:
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* 1 on successful parse, 0 on EOF, -errno on failure.
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*/
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static int cuse_parse_one(char **pp, char *end, char **keyp, char **valp)
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{
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char *p = *pp;
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char *key, *val;
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while (p < end && *p == '\0')
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p++;
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if (p == end)
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return 0;
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if (end[-1] != '\0') {
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pr_err("info not properly terminated\n");
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return -EINVAL;
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}
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key = val = p;
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p += strlen(p);
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if (valp) {
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strsep(&val, "=");
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if (!val)
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val = key + strlen(key);
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key = strstrip(key);
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val = strstrip(val);
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} else
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key = strstrip(key);
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if (!strlen(key)) {
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pr_err("zero length info key specified\n");
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return -EINVAL;
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}
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*pp = p;
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*keyp = key;
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if (valp)
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*valp = val;
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return 1;
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}
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/**
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* cuse_parse_dev_info - parse device info
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* @p: device info string
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* @len: length of device info string
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* @devinfo: out parameter for parsed device info
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*
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* Parse @p to extract device info and store it into @devinfo. String
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* pointed to by @p is modified by parsing and @devinfo points into
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* them, so @p shouldn't be freed while @devinfo is in use.
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*
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* RETURNS:
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* 0 on success, -errno on failure.
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*/
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static int cuse_parse_devinfo(char *p, size_t len, struct cuse_devinfo *devinfo)
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{
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char *end = p + len;
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char *uninitialized_var(key), *uninitialized_var(val);
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int rc;
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while (true) {
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rc = cuse_parse_one(&p, end, &key, &val);
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if (rc < 0)
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return rc;
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if (!rc)
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break;
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if (strcmp(key, "DEVNAME") == 0)
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devinfo->name = val;
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else
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pr_warn("unknown device info \"%s\"\n", key);
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}
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if (!devinfo->name || !strlen(devinfo->name)) {
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pr_err("DEVNAME unspecified\n");
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return -EINVAL;
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}
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return 0;
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}
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static void cuse_gendev_release(struct device *dev)
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{
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kfree(dev);
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}
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struct cuse_init_args {
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struct fuse_args_pages ap;
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struct cuse_init_in in;
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struct cuse_init_out out;
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struct page *page;
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struct fuse_page_desc desc;
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};
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/**
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* cuse_process_init_reply - finish initializing CUSE channel
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*
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* This function creates the character device and sets up all the
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* required data structures for it. Please read the comment at the
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* top of this file for high level overview.
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*/
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static void cuse_process_init_reply(struct fuse_conn *fc,
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struct fuse_args *args, int error)
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{
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struct cuse_init_args *ia = container_of(args, typeof(*ia), ap.args);
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struct fuse_args_pages *ap = &ia->ap;
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struct cuse_conn *cc = fc_to_cc(fc), *pos;
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struct cuse_init_out *arg = &ia->out;
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struct page *page = ap->pages[0];
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struct cuse_devinfo devinfo = { };
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struct device *dev;
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struct cdev *cdev;
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dev_t devt;
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int rc, i;
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if (error || arg->major != FUSE_KERNEL_VERSION || arg->minor < 11)
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goto err;
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fc->minor = arg->minor;
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fc->max_read = max_t(unsigned, arg->max_read, 4096);
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fc->max_write = max_t(unsigned, arg->max_write, 4096);
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/* parse init reply */
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cc->unrestricted_ioctl = arg->flags & CUSE_UNRESTRICTED_IOCTL;
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rc = cuse_parse_devinfo(page_address(page), ap->args.out_args[1].size,
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&devinfo);
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if (rc)
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goto err;
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/* determine and reserve devt */
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devt = MKDEV(arg->dev_major, arg->dev_minor);
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if (!MAJOR(devt))
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rc = alloc_chrdev_region(&devt, MINOR(devt), 1, devinfo.name);
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else
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rc = register_chrdev_region(devt, 1, devinfo.name);
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if (rc) {
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pr_err("failed to register chrdev region\n");
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goto err;
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}
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/* devt determined, create device */
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rc = -ENOMEM;
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dev = kzalloc(sizeof(*dev), GFP_KERNEL);
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if (!dev)
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goto err_region;
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device_initialize(dev);
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dev_set_uevent_suppress(dev, 1);
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dev->class = cuse_class;
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dev->devt = devt;
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dev->release = cuse_gendev_release;
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dev_set_drvdata(dev, cc);
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dev_set_name(dev, "%s", devinfo.name);
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mutex_lock(&cuse_lock);
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/* make sure the device-name is unique */
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for (i = 0; i < CUSE_CONNTBL_LEN; ++i) {
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list_for_each_entry(pos, &cuse_conntbl[i], list)
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if (!strcmp(dev_name(pos->dev), dev_name(dev)))
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goto err_unlock;
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}
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rc = device_add(dev);
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if (rc)
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goto err_unlock;
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/* register cdev */
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rc = -ENOMEM;
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cdev = cdev_alloc();
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if (!cdev)
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goto err_unlock;
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cdev->owner = THIS_MODULE;
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cdev->ops = &cuse_frontend_fops;
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rc = cdev_add(cdev, devt, 1);
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if (rc)
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goto err_cdev;
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cc->dev = dev;
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cc->cdev = cdev;
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/* make the device available */
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list_add(&cc->list, cuse_conntbl_head(devt));
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mutex_unlock(&cuse_lock);
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/* announce device availability */
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dev_set_uevent_suppress(dev, 0);
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kobject_uevent(&dev->kobj, KOBJ_ADD);
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out:
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kfree(ia);
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__free_page(page);
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return;
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err_cdev:
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cdev_del(cdev);
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err_unlock:
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mutex_unlock(&cuse_lock);
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put_device(dev);
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err_region:
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unregister_chrdev_region(devt, 1);
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err:
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fuse_abort_conn(fc);
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goto out;
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}
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static int cuse_send_init(struct cuse_conn *cc)
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{
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int rc;
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struct page *page;
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struct fuse_conn *fc = &cc->fc;
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struct cuse_init_args *ia;
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struct fuse_args_pages *ap;
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BUILD_BUG_ON(CUSE_INIT_INFO_MAX > PAGE_SIZE);
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rc = -ENOMEM;
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page = alloc_page(GFP_KERNEL | __GFP_ZERO);
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if (!page)
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goto err;
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ia = kzalloc(sizeof(*ia), GFP_KERNEL);
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if (!ia)
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goto err_free_page;
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ap = &ia->ap;
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ia->in.major = FUSE_KERNEL_VERSION;
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ia->in.minor = FUSE_KERNEL_MINOR_VERSION;
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ia->in.flags |= CUSE_UNRESTRICTED_IOCTL;
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ap->args.opcode = CUSE_INIT;
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ap->args.in_numargs = 1;
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ap->args.in_args[0].size = sizeof(ia->in);
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ap->args.in_args[0].value = &ia->in;
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ap->args.out_numargs = 2;
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ap->args.out_args[0].size = sizeof(ia->out);
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ap->args.out_args[0].value = &ia->out;
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ap->args.out_args[1].size = CUSE_INIT_INFO_MAX;
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ap->args.out_argvar = true;
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ap->args.out_pages = true;
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ap->num_pages = 1;
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ap->pages = &ia->page;
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ap->descs = &ia->desc;
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ia->page = page;
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ia->desc.length = ap->args.out_args[1].size;
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ap->args.end = cuse_process_init_reply;
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rc = fuse_simple_background(fc, &ap->args, GFP_KERNEL);
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if (rc) {
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kfree(ia);
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err_free_page:
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__free_page(page);
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}
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err:
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return rc;
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}
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static void cuse_fc_release(struct fuse_conn *fc)
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{
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struct cuse_conn *cc = fc_to_cc(fc);
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kfree_rcu(cc, fc.rcu);
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}
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/**
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* cuse_channel_open - open method for /dev/cuse
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* @inode: inode for /dev/cuse
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* @file: file struct being opened
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*
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* Userland CUSE server can create a CUSE device by opening /dev/cuse
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* and replying to the initialization request kernel sends. This
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* function is responsible for handling CUSE device initialization.
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* Because the fd opened by this function is used during
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* initialization, this function only creates cuse_conn and sends
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* init. The rest is delegated to a kthread.
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*
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* RETURNS:
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* 0 on success, -errno on failure.
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*/
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static int cuse_channel_open(struct inode *inode, struct file *file)
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{
|
|
struct fuse_dev *fud;
|
|
struct cuse_conn *cc;
|
|
int rc;
|
|
|
|
/* set up cuse_conn */
|
|
cc = kzalloc(sizeof(*cc), GFP_KERNEL);
|
|
if (!cc)
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* Limit the cuse channel to requests that can
|
|
* be represented in file->f_cred->user_ns.
|
|
*/
|
|
fuse_conn_init(&cc->fc, file->f_cred->user_ns, &fuse_dev_fiq_ops, NULL);
|
|
|
|
fud = fuse_dev_alloc_install(&cc->fc);
|
|
if (!fud) {
|
|
kfree(cc);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
INIT_LIST_HEAD(&cc->list);
|
|
cc->fc.release = cuse_fc_release;
|
|
|
|
cc->fc.initialized = 1;
|
|
rc = cuse_send_init(cc);
|
|
if (rc) {
|
|
fuse_dev_free(fud);
|
|
fuse_conn_put(&cc->fc);
|
|
return rc;
|
|
}
|
|
file->private_data = fud;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cuse_channel_release - release method for /dev/cuse
|
|
* @inode: inode for /dev/cuse
|
|
* @file: file struct being closed
|
|
*
|
|
* Disconnect the channel, deregister CUSE device and initiate
|
|
* destruction by putting the default reference.
|
|
*
|
|
* RETURNS:
|
|
* 0 on success, -errno on failure.
|
|
*/
|
|
static int cuse_channel_release(struct inode *inode, struct file *file)
|
|
{
|
|
struct fuse_dev *fud = file->private_data;
|
|
struct cuse_conn *cc = fc_to_cc(fud->fc);
|
|
int rc;
|
|
|
|
/* remove from the conntbl, no more access from this point on */
|
|
mutex_lock(&cuse_lock);
|
|
list_del_init(&cc->list);
|
|
mutex_unlock(&cuse_lock);
|
|
|
|
/* remove device */
|
|
if (cc->dev)
|
|
device_unregister(cc->dev);
|
|
if (cc->cdev) {
|
|
unregister_chrdev_region(cc->cdev->dev, 1);
|
|
cdev_del(cc->cdev);
|
|
}
|
|
/* Base reference is now owned by "fud" */
|
|
fuse_conn_put(&cc->fc);
|
|
|
|
rc = fuse_dev_release(inode, file); /* puts the base reference */
|
|
|
|
return rc;
|
|
}
|
|
|
|
static struct file_operations cuse_channel_fops; /* initialized during init */
|
|
|
|
|
|
/**************************************************************************
|
|
* Misc stuff and module initializatiion
|
|
*
|
|
* CUSE exports the same set of attributes to sysfs as fusectl.
|
|
*/
|
|
|
|
static ssize_t cuse_class_waiting_show(struct device *dev,
|
|
struct device_attribute *attr, char *buf)
|
|
{
|
|
struct cuse_conn *cc = dev_get_drvdata(dev);
|
|
|
|
return sprintf(buf, "%d\n", atomic_read(&cc->fc.num_waiting));
|
|
}
|
|
static DEVICE_ATTR(waiting, 0400, cuse_class_waiting_show, NULL);
|
|
|
|
static ssize_t cuse_class_abort_store(struct device *dev,
|
|
struct device_attribute *attr,
|
|
const char *buf, size_t count)
|
|
{
|
|
struct cuse_conn *cc = dev_get_drvdata(dev);
|
|
|
|
fuse_abort_conn(&cc->fc);
|
|
return count;
|
|
}
|
|
static DEVICE_ATTR(abort, 0200, NULL, cuse_class_abort_store);
|
|
|
|
static struct attribute *cuse_class_dev_attrs[] = {
|
|
&dev_attr_waiting.attr,
|
|
&dev_attr_abort.attr,
|
|
NULL,
|
|
};
|
|
ATTRIBUTE_GROUPS(cuse_class_dev);
|
|
|
|
static struct miscdevice cuse_miscdev = {
|
|
.minor = CUSE_MINOR,
|
|
.name = "cuse",
|
|
.fops = &cuse_channel_fops,
|
|
};
|
|
|
|
MODULE_ALIAS_MISCDEV(CUSE_MINOR);
|
|
MODULE_ALIAS("devname:cuse");
|
|
|
|
static int __init cuse_init(void)
|
|
{
|
|
int i, rc;
|
|
|
|
/* init conntbl */
|
|
for (i = 0; i < CUSE_CONNTBL_LEN; i++)
|
|
INIT_LIST_HEAD(&cuse_conntbl[i]);
|
|
|
|
/* inherit and extend fuse_dev_operations */
|
|
cuse_channel_fops = fuse_dev_operations;
|
|
cuse_channel_fops.owner = THIS_MODULE;
|
|
cuse_channel_fops.open = cuse_channel_open;
|
|
cuse_channel_fops.release = cuse_channel_release;
|
|
|
|
cuse_class = class_create(THIS_MODULE, "cuse");
|
|
if (IS_ERR(cuse_class))
|
|
return PTR_ERR(cuse_class);
|
|
|
|
cuse_class->dev_groups = cuse_class_dev_groups;
|
|
|
|
rc = misc_register(&cuse_miscdev);
|
|
if (rc) {
|
|
class_destroy(cuse_class);
|
|
return rc;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void __exit cuse_exit(void)
|
|
{
|
|
misc_deregister(&cuse_miscdev);
|
|
class_destroy(cuse_class);
|
|
}
|
|
|
|
module_init(cuse_init);
|
|
module_exit(cuse_exit);
|
|
|
|
MODULE_AUTHOR("Tejun Heo <tj@kernel.org>");
|
|
MODULE_DESCRIPTION("Character device in Userspace");
|
|
MODULE_LICENSE("GPL");
|