forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
362 lines
8.3 KiB
362 lines
8.3 KiB
// SPDX-License-Identifier: GPL-2.0-only |
|
/* |
|
* linux/drivers/char/raw.c |
|
* |
|
* Front-end raw character devices. These can be bound to any block |
|
* devices to provide genuine Unix raw character device semantics. |
|
* |
|
* We reserve minor number 0 for a control interface. ioctl()s on this |
|
* device are used to bind the other minor numbers to block devices. |
|
*/ |
|
|
|
#include <linux/init.h> |
|
#include <linux/fs.h> |
|
#include <linux/major.h> |
|
#include <linux/blkdev.h> |
|
#include <linux/backing-dev.h> |
|
#include <linux/module.h> |
|
#include <linux/raw.h> |
|
#include <linux/capability.h> |
|
#include <linux/uio.h> |
|
#include <linux/cdev.h> |
|
#include <linux/device.h> |
|
#include <linux/mutex.h> |
|
#include <linux/gfp.h> |
|
#include <linux/compat.h> |
|
#include <linux/vmalloc.h> |
|
|
|
#include <linux/uaccess.h> |
|
|
|
struct raw_device_data { |
|
dev_t binding; |
|
struct block_device *bdev; |
|
int inuse; |
|
}; |
|
|
|
static struct class *raw_class; |
|
static struct raw_device_data *raw_devices; |
|
static DEFINE_MUTEX(raw_mutex); |
|
static const struct file_operations raw_ctl_fops; /* forward declaration */ |
|
|
|
static int max_raw_minors = CONFIG_MAX_RAW_DEVS; |
|
|
|
module_param(max_raw_minors, int, 0); |
|
MODULE_PARM_DESC(max_raw_minors, "Maximum number of raw devices (1-65536)"); |
|
|
|
/* |
|
* Open/close code for raw IO. |
|
* |
|
* We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to |
|
* point at the blockdev's address_space and set the file handle to use |
|
* O_DIRECT. |
|
* |
|
* Set the device's soft blocksize to the minimum possible. This gives the |
|
* finest possible alignment and has no adverse impact on performance. |
|
*/ |
|
static int raw_open(struct inode *inode, struct file *filp) |
|
{ |
|
const int minor = iminor(inode); |
|
struct block_device *bdev; |
|
int err; |
|
|
|
if (minor == 0) { /* It is the control device */ |
|
filp->f_op = &raw_ctl_fops; |
|
return 0; |
|
} |
|
|
|
pr_warn_ratelimited( |
|
"process %s (pid %d) is using the deprecated raw device\n" |
|
"support will be removed in Linux 5.14.\n", |
|
current->comm, current->pid); |
|
|
|
mutex_lock(&raw_mutex); |
|
|
|
/* |
|
* All we need to do on open is check that the device is bound. |
|
*/ |
|
err = -ENODEV; |
|
if (!raw_devices[minor].binding) |
|
goto out; |
|
bdev = blkdev_get_by_dev(raw_devices[minor].binding, |
|
filp->f_mode | FMODE_EXCL, raw_open); |
|
if (IS_ERR(bdev)) { |
|
err = PTR_ERR(bdev); |
|
goto out; |
|
} |
|
err = set_blocksize(bdev, bdev_logical_block_size(bdev)); |
|
if (err) |
|
goto out1; |
|
filp->f_flags |= O_DIRECT; |
|
filp->f_mapping = bdev->bd_inode->i_mapping; |
|
if (++raw_devices[minor].inuse == 1) |
|
file_inode(filp)->i_mapping = |
|
bdev->bd_inode->i_mapping; |
|
filp->private_data = bdev; |
|
raw_devices[minor].bdev = bdev; |
|
mutex_unlock(&raw_mutex); |
|
return 0; |
|
|
|
out1: |
|
blkdev_put(bdev, filp->f_mode | FMODE_EXCL); |
|
out: |
|
mutex_unlock(&raw_mutex); |
|
return err; |
|
} |
|
|
|
/* |
|
* When the final fd which refers to this character-special node is closed, we |
|
* make its ->mapping point back at its own i_data. |
|
*/ |
|
static int raw_release(struct inode *inode, struct file *filp) |
|
{ |
|
const int minor= iminor(inode); |
|
struct block_device *bdev; |
|
|
|
mutex_lock(&raw_mutex); |
|
bdev = raw_devices[minor].bdev; |
|
if (--raw_devices[minor].inuse == 0) |
|
/* Here inode->i_mapping == bdev->bd_inode->i_mapping */ |
|
inode->i_mapping = &inode->i_data; |
|
mutex_unlock(&raw_mutex); |
|
|
|
blkdev_put(bdev, filp->f_mode | FMODE_EXCL); |
|
return 0; |
|
} |
|
|
|
/* |
|
* Forward ioctls to the underlying block device. |
|
*/ |
|
static long |
|
raw_ioctl(struct file *filp, unsigned int command, unsigned long arg) |
|
{ |
|
struct block_device *bdev = filp->private_data; |
|
return blkdev_ioctl(bdev, 0, command, arg); |
|
} |
|
|
|
static int bind_set(int number, u64 major, u64 minor) |
|
{ |
|
dev_t dev = MKDEV(major, minor); |
|
dev_t raw = MKDEV(RAW_MAJOR, number); |
|
struct raw_device_data *rawdev; |
|
int err = 0; |
|
|
|
if (number <= 0 || number >= max_raw_minors) |
|
return -EINVAL; |
|
|
|
if (MAJOR(dev) != major || MINOR(dev) != minor) |
|
return -EINVAL; |
|
|
|
rawdev = &raw_devices[number]; |
|
|
|
/* |
|
* This is like making block devices, so demand the |
|
* same capability |
|
*/ |
|
if (!capable(CAP_SYS_ADMIN)) |
|
return -EPERM; |
|
|
|
/* |
|
* For now, we don't need to check that the underlying |
|
* block device is present or not: we can do that when |
|
* the raw device is opened. Just check that the |
|
* major/minor numbers make sense. |
|
*/ |
|
|
|
if (MAJOR(dev) == 0 && dev != 0) |
|
return -EINVAL; |
|
|
|
mutex_lock(&raw_mutex); |
|
if (rawdev->inuse) { |
|
mutex_unlock(&raw_mutex); |
|
return -EBUSY; |
|
} |
|
if (rawdev->binding) |
|
module_put(THIS_MODULE); |
|
|
|
rawdev->binding = dev; |
|
if (!dev) { |
|
/* unbind */ |
|
device_destroy(raw_class, raw); |
|
} else { |
|
__module_get(THIS_MODULE); |
|
device_destroy(raw_class, raw); |
|
device_create(raw_class, NULL, raw, NULL, "raw%d", number); |
|
} |
|
mutex_unlock(&raw_mutex); |
|
return err; |
|
} |
|
|
|
static int bind_get(int number, dev_t *dev) |
|
{ |
|
if (number <= 0 || number >= max_raw_minors) |
|
return -EINVAL; |
|
*dev = raw_devices[number].binding; |
|
return 0; |
|
} |
|
|
|
/* |
|
* Deal with ioctls against the raw-device control interface, to bind |
|
* and unbind other raw devices. |
|
*/ |
|
static long raw_ctl_ioctl(struct file *filp, unsigned int command, |
|
unsigned long arg) |
|
{ |
|
struct raw_config_request rq; |
|
dev_t dev; |
|
int err; |
|
|
|
switch (command) { |
|
case RAW_SETBIND: |
|
if (copy_from_user(&rq, (void __user *) arg, sizeof(rq))) |
|
return -EFAULT; |
|
|
|
return bind_set(rq.raw_minor, rq.block_major, rq.block_minor); |
|
|
|
case RAW_GETBIND: |
|
if (copy_from_user(&rq, (void __user *) arg, sizeof(rq))) |
|
return -EFAULT; |
|
|
|
err = bind_get(rq.raw_minor, &dev); |
|
if (err) |
|
return err; |
|
|
|
rq.block_major = MAJOR(dev); |
|
rq.block_minor = MINOR(dev); |
|
|
|
if (copy_to_user((void __user *)arg, &rq, sizeof(rq))) |
|
return -EFAULT; |
|
|
|
return 0; |
|
} |
|
|
|
return -EINVAL; |
|
} |
|
|
|
#ifdef CONFIG_COMPAT |
|
struct raw32_config_request { |
|
compat_int_t raw_minor; |
|
compat_u64 block_major; |
|
compat_u64 block_minor; |
|
}; |
|
|
|
static long raw_ctl_compat_ioctl(struct file *file, unsigned int cmd, |
|
unsigned long arg) |
|
{ |
|
struct raw32_config_request __user *user_req = compat_ptr(arg); |
|
struct raw32_config_request rq; |
|
dev_t dev; |
|
int err = 0; |
|
|
|
switch (cmd) { |
|
case RAW_SETBIND: |
|
if (copy_from_user(&rq, user_req, sizeof(rq))) |
|
return -EFAULT; |
|
|
|
return bind_set(rq.raw_minor, rq.block_major, rq.block_minor); |
|
|
|
case RAW_GETBIND: |
|
if (copy_from_user(&rq, user_req, sizeof(rq))) |
|
return -EFAULT; |
|
|
|
err = bind_get(rq.raw_minor, &dev); |
|
if (err) |
|
return err; |
|
|
|
rq.block_major = MAJOR(dev); |
|
rq.block_minor = MINOR(dev); |
|
|
|
if (copy_to_user(user_req, &rq, sizeof(rq))) |
|
return -EFAULT; |
|
|
|
return 0; |
|
} |
|
|
|
return -EINVAL; |
|
} |
|
#endif |
|
|
|
static const struct file_operations raw_fops = { |
|
.read_iter = blkdev_read_iter, |
|
.write_iter = blkdev_write_iter, |
|
.fsync = blkdev_fsync, |
|
.open = raw_open, |
|
.release = raw_release, |
|
.unlocked_ioctl = raw_ioctl, |
|
.llseek = default_llseek, |
|
.owner = THIS_MODULE, |
|
}; |
|
|
|
static const struct file_operations raw_ctl_fops = { |
|
.unlocked_ioctl = raw_ctl_ioctl, |
|
#ifdef CONFIG_COMPAT |
|
.compat_ioctl = raw_ctl_compat_ioctl, |
|
#endif |
|
.open = raw_open, |
|
.owner = THIS_MODULE, |
|
.llseek = noop_llseek, |
|
}; |
|
|
|
static struct cdev raw_cdev; |
|
|
|
static char *raw_devnode(struct device *dev, umode_t *mode) |
|
{ |
|
return kasprintf(GFP_KERNEL, "raw/%s", dev_name(dev)); |
|
} |
|
|
|
static int __init raw_init(void) |
|
{ |
|
dev_t dev = MKDEV(RAW_MAJOR, 0); |
|
int ret; |
|
|
|
if (max_raw_minors < 1 || max_raw_minors > 65536) { |
|
pr_warn("raw: invalid max_raw_minors (must be between 1 and 65536), using %d\n", |
|
CONFIG_MAX_RAW_DEVS); |
|
max_raw_minors = CONFIG_MAX_RAW_DEVS; |
|
} |
|
|
|
raw_devices = vzalloc(array_size(max_raw_minors, |
|
sizeof(struct raw_device_data))); |
|
if (!raw_devices) { |
|
printk(KERN_ERR "Not enough memory for raw device structures\n"); |
|
ret = -ENOMEM; |
|
goto error; |
|
} |
|
|
|
ret = register_chrdev_region(dev, max_raw_minors, "raw"); |
|
if (ret) |
|
goto error; |
|
|
|
cdev_init(&raw_cdev, &raw_fops); |
|
ret = cdev_add(&raw_cdev, dev, max_raw_minors); |
|
if (ret) |
|
goto error_region; |
|
raw_class = class_create(THIS_MODULE, "raw"); |
|
if (IS_ERR(raw_class)) { |
|
printk(KERN_ERR "Error creating raw class.\n"); |
|
cdev_del(&raw_cdev); |
|
ret = PTR_ERR(raw_class); |
|
goto error_region; |
|
} |
|
raw_class->devnode = raw_devnode; |
|
device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl"); |
|
|
|
return 0; |
|
|
|
error_region: |
|
unregister_chrdev_region(dev, max_raw_minors); |
|
error: |
|
vfree(raw_devices); |
|
return ret; |
|
} |
|
|
|
static void __exit raw_exit(void) |
|
{ |
|
device_destroy(raw_class, MKDEV(RAW_MAJOR, 0)); |
|
class_destroy(raw_class); |
|
cdev_del(&raw_cdev); |
|
unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), max_raw_minors); |
|
} |
|
|
|
module_init(raw_init); |
|
module_exit(raw_exit); |
|
MODULE_LICENSE("GPL");
|
|
|