4503efd089
Some sysfs binary files don't like having 0 passed to them as a size. Fix this up at the root by just returning to the vfs if userspace asks us for a zero sized buffer. Thanks to Pavel Roskin for pointing this out. Reported-by: Pavel Roskin <proski@gnu.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
285 lines
5.9 KiB
C
285 lines
5.9 KiB
C
/*
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* fs/sysfs/bin.c - sysfs binary file implementation
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*
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* Copyright (c) 2003 Patrick Mochel
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* Copyright (c) 2003 Matthew Wilcox
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* Copyright (c) 2004 Silicon Graphics, Inc.
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* Copyright (c) 2007 SUSE Linux Products GmbH
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* Copyright (c) 2007 Tejun Heo <teheo@suse.de>
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*
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* This file is released under the GPLv2.
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*
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* Please see Documentation/filesystems/sysfs.txt for more information.
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*/
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#undef DEBUG
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#include <linux/errno.h>
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#include <linux/fs.h>
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#include <linux/kernel.h>
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#include <linux/kobject.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/mutex.h>
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#include <asm/uaccess.h>
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#include "sysfs.h"
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struct bin_buffer {
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struct mutex mutex;
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void *buffer;
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int mmapped;
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};
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static int
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fill_read(struct dentry *dentry, char *buffer, loff_t off, size_t count)
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{
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struct sysfs_dirent *attr_sd = dentry->d_fsdata;
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struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
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struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
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int rc;
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/* need attr_sd for attr, its parent for kobj */
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if (!sysfs_get_active_two(attr_sd))
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return -ENODEV;
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rc = -EIO;
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if (attr->read)
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rc = attr->read(kobj, attr, buffer, off, count);
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sysfs_put_active_two(attr_sd);
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return rc;
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}
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static ssize_t
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read(struct file *file, char __user *userbuf, size_t bytes, loff_t *off)
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{
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struct bin_buffer *bb = file->private_data;
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struct dentry *dentry = file->f_path.dentry;
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int size = dentry->d_inode->i_size;
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loff_t offs = *off;
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int count = min_t(size_t, bytes, PAGE_SIZE);
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char *temp;
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if (!bytes)
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return 0;
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if (size) {
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if (offs > size)
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return 0;
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if (offs + count > size)
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count = size - offs;
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}
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temp = kmalloc(count, GFP_KERNEL);
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if (!temp)
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return -ENOMEM;
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mutex_lock(&bb->mutex);
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count = fill_read(dentry, bb->buffer, offs, count);
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if (count < 0) {
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mutex_unlock(&bb->mutex);
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goto out_free;
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}
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memcpy(temp, bb->buffer, count);
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mutex_unlock(&bb->mutex);
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if (copy_to_user(userbuf, temp, count)) {
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count = -EFAULT;
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goto out_free;
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}
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pr_debug("offs = %lld, *off = %lld, count = %d\n", offs, *off, count);
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*off = offs + count;
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out_free:
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kfree(temp);
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return count;
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}
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static int
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flush_write(struct dentry *dentry, char *buffer, loff_t offset, size_t count)
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{
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struct sysfs_dirent *attr_sd = dentry->d_fsdata;
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struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
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struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
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int rc;
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/* need attr_sd for attr, its parent for kobj */
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if (!sysfs_get_active_two(attr_sd))
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return -ENODEV;
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rc = -EIO;
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if (attr->write)
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rc = attr->write(kobj, attr, buffer, offset, count);
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sysfs_put_active_two(attr_sd);
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return rc;
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}
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static ssize_t write(struct file *file, const char __user *userbuf,
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size_t bytes, loff_t *off)
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{
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struct bin_buffer *bb = file->private_data;
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struct dentry *dentry = file->f_path.dentry;
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int size = dentry->d_inode->i_size;
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loff_t offs = *off;
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int count = min_t(size_t, bytes, PAGE_SIZE);
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char *temp;
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if (!bytes)
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return 0;
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if (size) {
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if (offs > size)
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return 0;
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if (offs + count > size)
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count = size - offs;
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}
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temp = kmalloc(count, GFP_KERNEL);
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if (!temp)
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return -ENOMEM;
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if (copy_from_user(temp, userbuf, count)) {
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count = -EFAULT;
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goto out_free;
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}
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mutex_lock(&bb->mutex);
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memcpy(bb->buffer, temp, count);
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count = flush_write(dentry, bb->buffer, offs, count);
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mutex_unlock(&bb->mutex);
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if (count > 0)
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*off = offs + count;
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out_free:
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kfree(temp);
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return count;
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}
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static int mmap(struct file *file, struct vm_area_struct *vma)
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{
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struct bin_buffer *bb = file->private_data;
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struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
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struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
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struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
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int rc;
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mutex_lock(&bb->mutex);
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/* need attr_sd for attr, its parent for kobj */
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if (!sysfs_get_active_two(attr_sd))
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return -ENODEV;
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rc = -EINVAL;
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if (attr->mmap)
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rc = attr->mmap(kobj, attr, vma);
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if (rc == 0 && !bb->mmapped)
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bb->mmapped = 1;
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else
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sysfs_put_active_two(attr_sd);
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mutex_unlock(&bb->mutex);
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return rc;
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}
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static int open(struct inode * inode, struct file * file)
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{
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struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
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struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
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struct bin_buffer *bb = NULL;
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int error;
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/* binary file operations requires both @sd and its parent */
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if (!sysfs_get_active_two(attr_sd))
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return -ENODEV;
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error = -EACCES;
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if ((file->f_mode & FMODE_WRITE) && !(attr->write || attr->mmap))
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goto err_out;
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if ((file->f_mode & FMODE_READ) && !(attr->read || attr->mmap))
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goto err_out;
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error = -ENOMEM;
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bb = kzalloc(sizeof(*bb), GFP_KERNEL);
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if (!bb)
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goto err_out;
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bb->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
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if (!bb->buffer)
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goto err_out;
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mutex_init(&bb->mutex);
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file->private_data = bb;
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/* open succeeded, put active references */
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sysfs_put_active_two(attr_sd);
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return 0;
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err_out:
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sysfs_put_active_two(attr_sd);
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kfree(bb);
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return error;
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}
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static int release(struct inode * inode, struct file * file)
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{
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struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
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struct bin_buffer *bb = file->private_data;
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if (bb->mmapped)
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sysfs_put_active_two(attr_sd);
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kfree(bb->buffer);
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kfree(bb);
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return 0;
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}
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const struct file_operations bin_fops = {
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.read = read,
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.write = write,
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.mmap = mmap,
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.llseek = generic_file_llseek,
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.open = open,
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.release = release,
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};
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/**
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* sysfs_create_bin_file - create binary file for object.
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* @kobj: object.
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* @attr: attribute descriptor.
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*/
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int sysfs_create_bin_file(struct kobject * kobj, struct bin_attribute * attr)
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{
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BUG_ON(!kobj || !kobj->sd || !attr);
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return sysfs_add_file(kobj->sd, &attr->attr, SYSFS_KOBJ_BIN_ATTR);
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}
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/**
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* sysfs_remove_bin_file - remove binary file for object.
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* @kobj: object.
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* @attr: attribute descriptor.
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*/
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void sysfs_remove_bin_file(struct kobject * kobj, struct bin_attribute * attr)
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{
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sysfs_hash_and_remove(kobj->sd, attr->attr.name);
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}
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EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
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EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);
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