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7c0f6ba682
This was entirely automated, using the script by Al: PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>' sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \ $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h) to do the replacement at the end of the merge window. Requested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
571 lines
15 KiB
C
571 lines
15 KiB
C
/* -*- mode: c; c-basic-offset: 8; -*-
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* vim: noexpandtab sw=8 ts=8 sts=0:
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*
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* file.c - operations for regular (text) files.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*
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* Based on sysfs:
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* sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
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*
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* configfs Copyright (C) 2005 Oracle. All rights reserved.
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*/
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#include <linux/fs.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 <linux/vmalloc.h>
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#include <linux/uaccess.h>
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#include <linux/configfs.h>
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#include "configfs_internal.h"
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/*
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* A simple attribute can only be 4096 characters. Why 4k? Because the
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* original code limited it to PAGE_SIZE. That's a bad idea, though,
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* because an attribute of 16k on ia64 won't work on x86. So we limit to
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* 4k, our minimum common page size.
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*/
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#define SIMPLE_ATTR_SIZE 4096
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struct configfs_buffer {
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size_t count;
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loff_t pos;
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char * page;
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struct configfs_item_operations * ops;
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struct mutex mutex;
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int needs_read_fill;
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bool read_in_progress;
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bool write_in_progress;
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char *bin_buffer;
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int bin_buffer_size;
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};
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/**
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* fill_read_buffer - allocate and fill buffer from item.
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* @dentry: dentry pointer.
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* @buffer: data buffer for file.
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*
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* Allocate @buffer->page, if it hasn't been already, then call the
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* config_item's show() method to fill the buffer with this attribute's
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* data.
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* This is called only once, on the file's first read.
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*/
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static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buffer)
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{
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struct configfs_attribute * attr = to_attr(dentry);
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struct config_item * item = to_item(dentry->d_parent);
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int ret = 0;
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ssize_t count;
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if (!buffer->page)
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buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
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if (!buffer->page)
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return -ENOMEM;
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count = attr->show(item, buffer->page);
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BUG_ON(count > (ssize_t)SIMPLE_ATTR_SIZE);
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if (count >= 0) {
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buffer->needs_read_fill = 0;
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buffer->count = count;
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} else
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ret = count;
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return ret;
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}
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/**
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* configfs_read_file - read an attribute.
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* @file: file pointer.
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* @buf: buffer to fill.
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* @count: number of bytes to read.
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* @ppos: starting offset in file.
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*
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* Userspace wants to read an attribute file. The attribute descriptor
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* is in the file's ->d_fsdata. The target item is in the directory's
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* ->d_fsdata.
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*
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* We call fill_read_buffer() to allocate and fill the buffer from the
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* item's show() method exactly once (if the read is happening from
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* the beginning of the file). That should fill the entire buffer with
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* all the data the item has to offer for that attribute.
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* We then call flush_read_buffer() to copy the buffer to userspace
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* in the increments specified.
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*/
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static ssize_t
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configfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
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{
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struct configfs_buffer * buffer = file->private_data;
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ssize_t retval = 0;
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mutex_lock(&buffer->mutex);
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if (buffer->needs_read_fill) {
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if ((retval = fill_read_buffer(file->f_path.dentry,buffer)))
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goto out;
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}
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pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
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__func__, count, *ppos, buffer->page);
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retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
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buffer->count);
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out:
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mutex_unlock(&buffer->mutex);
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return retval;
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}
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/**
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* configfs_read_bin_file - read a binary attribute.
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* @file: file pointer.
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* @buf: buffer to fill.
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* @count: number of bytes to read.
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* @ppos: starting offset in file.
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*
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* Userspace wants to read a binary attribute file. The attribute
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* descriptor is in the file's ->d_fsdata. The target item is in the
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* directory's ->d_fsdata.
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*
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* We check whether we need to refill the buffer. If so we will
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* call the attributes' attr->read() twice. The first time we
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* will pass a NULL as a buffer pointer, which the attributes' method
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* will use to return the size of the buffer required. If no error
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* occurs we will allocate the buffer using vmalloc and call
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* attr->read() again passing that buffer as an argument.
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* Then we just copy to user-space using simple_read_from_buffer.
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*/
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static ssize_t
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configfs_read_bin_file(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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{
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struct configfs_buffer *buffer = file->private_data;
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struct dentry *dentry = file->f_path.dentry;
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struct config_item *item = to_item(dentry->d_parent);
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struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
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ssize_t retval = 0;
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ssize_t len = min_t(size_t, count, PAGE_SIZE);
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mutex_lock(&buffer->mutex);
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/* we don't support switching read/write modes */
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if (buffer->write_in_progress) {
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retval = -ETXTBSY;
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goto out;
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}
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buffer->read_in_progress = 1;
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if (buffer->needs_read_fill) {
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/* perform first read with buf == NULL to get extent */
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len = bin_attr->read(item, NULL, 0);
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if (len <= 0) {
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retval = len;
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goto out;
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}
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/* do not exceed the maximum value */
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if (bin_attr->cb_max_size && len > bin_attr->cb_max_size) {
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retval = -EFBIG;
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goto out;
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}
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buffer->bin_buffer = vmalloc(len);
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if (buffer->bin_buffer == NULL) {
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retval = -ENOMEM;
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goto out;
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}
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buffer->bin_buffer_size = len;
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/* perform second read to fill buffer */
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len = bin_attr->read(item, buffer->bin_buffer, len);
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if (len < 0) {
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retval = len;
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vfree(buffer->bin_buffer);
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buffer->bin_buffer_size = 0;
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buffer->bin_buffer = NULL;
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goto out;
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}
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buffer->needs_read_fill = 0;
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}
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retval = simple_read_from_buffer(buf, count, ppos, buffer->bin_buffer,
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buffer->bin_buffer_size);
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out:
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mutex_unlock(&buffer->mutex);
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return retval;
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}
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/**
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* fill_write_buffer - copy buffer from userspace.
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* @buffer: data buffer for file.
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* @buf: data from user.
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* @count: number of bytes in @userbuf.
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*
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* Allocate @buffer->page if it hasn't been already, then
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* copy the user-supplied buffer into it.
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*/
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static int
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fill_write_buffer(struct configfs_buffer * buffer, const char __user * buf, size_t count)
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{
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int error;
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if (!buffer->page)
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buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0);
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if (!buffer->page)
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return -ENOMEM;
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if (count >= SIMPLE_ATTR_SIZE)
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count = SIMPLE_ATTR_SIZE - 1;
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error = copy_from_user(buffer->page,buf,count);
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buffer->needs_read_fill = 1;
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/* if buf is assumed to contain a string, terminate it by \0,
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* so e.g. sscanf() can scan the string easily */
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buffer->page[count] = 0;
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return error ? -EFAULT : count;
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}
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/**
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* flush_write_buffer - push buffer to config_item.
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* @dentry: dentry to the attribute
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* @buffer: data buffer for file.
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* @count: number of bytes
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*
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* Get the correct pointers for the config_item and the attribute we're
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* dealing with, then call the store() method for the attribute,
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* passing the buffer that we acquired in fill_write_buffer().
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*/
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static int
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flush_write_buffer(struct dentry * dentry, struct configfs_buffer * buffer, size_t count)
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{
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struct configfs_attribute * attr = to_attr(dentry);
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struct config_item * item = to_item(dentry->d_parent);
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return attr->store(item, buffer->page, count);
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}
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/**
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* configfs_write_file - write an attribute.
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* @file: file pointer
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* @buf: data to write
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* @count: number of bytes
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* @ppos: starting offset
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*
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* Similar to configfs_read_file(), though working in the opposite direction.
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* We allocate and fill the data from the user in fill_write_buffer(),
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* then push it to the config_item in flush_write_buffer().
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* There is no easy way for us to know if userspace is only doing a partial
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* write, so we don't support them. We expect the entire buffer to come
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* on the first write.
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* Hint: if you're writing a value, first read the file, modify only the
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* the value you're changing, then write entire buffer back.
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*/
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static ssize_t
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configfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
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{
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struct configfs_buffer * buffer = file->private_data;
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ssize_t len;
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mutex_lock(&buffer->mutex);
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len = fill_write_buffer(buffer, buf, count);
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if (len > 0)
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len = flush_write_buffer(file->f_path.dentry, buffer, len);
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if (len > 0)
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*ppos += len;
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mutex_unlock(&buffer->mutex);
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return len;
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}
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/**
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* configfs_write_bin_file - write a binary attribute.
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* @file: file pointer
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* @buf: data to write
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* @count: number of bytes
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* @ppos: starting offset
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*
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* Writing to a binary attribute file is similar to a normal read.
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* We buffer the consecutive writes (binary attribute files do not
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* support lseek) in a continuously growing buffer, but we don't
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* commit until the close of the file.
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*/
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static ssize_t
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configfs_write_bin_file(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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struct configfs_buffer *buffer = file->private_data;
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struct dentry *dentry = file->f_path.dentry;
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struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
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void *tbuf = NULL;
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ssize_t len;
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mutex_lock(&buffer->mutex);
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/* we don't support switching read/write modes */
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if (buffer->read_in_progress) {
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len = -ETXTBSY;
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goto out;
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}
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buffer->write_in_progress = 1;
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/* buffer grows? */
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if (*ppos + count > buffer->bin_buffer_size) {
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if (bin_attr->cb_max_size &&
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*ppos + count > bin_attr->cb_max_size) {
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len = -EFBIG;
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goto out;
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}
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tbuf = vmalloc(*ppos + count);
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if (tbuf == NULL) {
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len = -ENOMEM;
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goto out;
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}
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/* copy old contents */
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if (buffer->bin_buffer) {
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memcpy(tbuf, buffer->bin_buffer,
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buffer->bin_buffer_size);
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vfree(buffer->bin_buffer);
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}
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/* clear the new area */
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memset(tbuf + buffer->bin_buffer_size, 0,
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*ppos + count - buffer->bin_buffer_size);
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buffer->bin_buffer = tbuf;
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buffer->bin_buffer_size = *ppos + count;
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}
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len = simple_write_to_buffer(buffer->bin_buffer,
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buffer->bin_buffer_size, ppos, buf, count);
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out:
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mutex_unlock(&buffer->mutex);
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return len;
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}
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static int check_perm(struct inode * inode, struct file * file, int type)
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{
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struct config_item *item = configfs_get_config_item(file->f_path.dentry->d_parent);
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struct configfs_attribute * attr = to_attr(file->f_path.dentry);
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struct configfs_bin_attribute *bin_attr = NULL;
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struct configfs_buffer * buffer;
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struct configfs_item_operations * ops = NULL;
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int error = 0;
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if (!item || !attr)
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goto Einval;
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if (type & CONFIGFS_ITEM_BIN_ATTR)
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bin_attr = to_bin_attr(file->f_path.dentry);
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/* Grab the module reference for this attribute if we have one */
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if (!try_module_get(attr->ca_owner)) {
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error = -ENODEV;
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goto Done;
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}
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if (item->ci_type)
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ops = item->ci_type->ct_item_ops;
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else
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goto Eaccess;
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/* File needs write support.
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* The inode's perms must say it's ok,
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* and we must have a store method.
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*/
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if (file->f_mode & FMODE_WRITE) {
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if (!(inode->i_mode & S_IWUGO))
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goto Eaccess;
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if ((type & CONFIGFS_ITEM_ATTR) && !attr->store)
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goto Eaccess;
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if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_attr->write)
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goto Eaccess;
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}
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/* File needs read support.
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* The inode's perms must say it's ok, and we there
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* must be a show method for it.
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*/
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if (file->f_mode & FMODE_READ) {
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if (!(inode->i_mode & S_IRUGO))
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goto Eaccess;
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if ((type & CONFIGFS_ITEM_ATTR) && !attr->show)
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goto Eaccess;
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if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_attr->read)
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goto Eaccess;
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}
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/* No error? Great, allocate a buffer for the file, and store it
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* it in file->private_data for easy access.
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*/
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buffer = kzalloc(sizeof(struct configfs_buffer),GFP_KERNEL);
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if (!buffer) {
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error = -ENOMEM;
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goto Enomem;
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}
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mutex_init(&buffer->mutex);
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buffer->needs_read_fill = 1;
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buffer->read_in_progress = 0;
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buffer->write_in_progress = 0;
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buffer->ops = ops;
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file->private_data = buffer;
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goto Done;
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Einval:
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error = -EINVAL;
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goto Done;
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Eaccess:
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error = -EACCES;
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Enomem:
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module_put(attr->ca_owner);
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Done:
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if (error && item)
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config_item_put(item);
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return error;
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}
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static int configfs_release(struct inode *inode, struct file *filp)
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{
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struct config_item * item = to_item(filp->f_path.dentry->d_parent);
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struct configfs_attribute * attr = to_attr(filp->f_path.dentry);
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struct module * owner = attr->ca_owner;
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struct configfs_buffer * buffer = filp->private_data;
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if (item)
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config_item_put(item);
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/* After this point, attr should not be accessed. */
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module_put(owner);
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if (buffer) {
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if (buffer->page)
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free_page((unsigned long)buffer->page);
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mutex_destroy(&buffer->mutex);
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kfree(buffer);
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}
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return 0;
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}
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static int configfs_open_file(struct inode *inode, struct file *filp)
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{
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return check_perm(inode, filp, CONFIGFS_ITEM_ATTR);
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}
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static int configfs_open_bin_file(struct inode *inode, struct file *filp)
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{
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return check_perm(inode, filp, CONFIGFS_ITEM_BIN_ATTR);
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}
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static int configfs_release_bin_file(struct inode *inode, struct file *filp)
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{
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struct configfs_buffer *buffer = filp->private_data;
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struct dentry *dentry = filp->f_path.dentry;
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struct config_item *item = to_item(dentry->d_parent);
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struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
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ssize_t len = 0;
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int ret;
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buffer->read_in_progress = 0;
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if (buffer->write_in_progress) {
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buffer->write_in_progress = 0;
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len = bin_attr->write(item, buffer->bin_buffer,
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buffer->bin_buffer_size);
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/* vfree on NULL is safe */
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vfree(buffer->bin_buffer);
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buffer->bin_buffer = NULL;
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buffer->bin_buffer_size = 0;
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buffer->needs_read_fill = 1;
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}
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ret = configfs_release(inode, filp);
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if (len < 0)
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return len;
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return ret;
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}
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const struct file_operations configfs_file_operations = {
|
|
.read = configfs_read_file,
|
|
.write = configfs_write_file,
|
|
.llseek = generic_file_llseek,
|
|
.open = configfs_open_file,
|
|
.release = configfs_release,
|
|
};
|
|
|
|
const struct file_operations configfs_bin_file_operations = {
|
|
.read = configfs_read_bin_file,
|
|
.write = configfs_write_bin_file,
|
|
.llseek = NULL, /* bin file is not seekable */
|
|
.open = configfs_open_bin_file,
|
|
.release = configfs_release_bin_file,
|
|
};
|
|
|
|
/**
|
|
* configfs_create_file - create an attribute file for an item.
|
|
* @item: item we're creating for.
|
|
* @attr: atrribute descriptor.
|
|
*/
|
|
|
|
int configfs_create_file(struct config_item * item, const struct configfs_attribute * attr)
|
|
{
|
|
struct dentry *dir = item->ci_dentry;
|
|
struct configfs_dirent *parent_sd = dir->d_fsdata;
|
|
umode_t mode = (attr->ca_mode & S_IALLUGO) | S_IFREG;
|
|
int error = 0;
|
|
|
|
inode_lock_nested(d_inode(dir), I_MUTEX_NORMAL);
|
|
error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode,
|
|
CONFIGFS_ITEM_ATTR);
|
|
inode_unlock(d_inode(dir));
|
|
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* configfs_create_bin_file - create a binary attribute file for an item.
|
|
* @item: item we're creating for.
|
|
* @attr: atrribute descriptor.
|
|
*/
|
|
|
|
int configfs_create_bin_file(struct config_item *item,
|
|
const struct configfs_bin_attribute *bin_attr)
|
|
{
|
|
struct dentry *dir = item->ci_dentry;
|
|
struct configfs_dirent *parent_sd = dir->d_fsdata;
|
|
umode_t mode = (bin_attr->cb_attr.ca_mode & S_IALLUGO) | S_IFREG;
|
|
int error = 0;
|
|
|
|
inode_lock_nested(dir->d_inode, I_MUTEX_NORMAL);
|
|
error = configfs_make_dirent(parent_sd, NULL, (void *) bin_attr, mode,
|
|
CONFIGFS_ITEM_BIN_ATTR);
|
|
inode_unlock(dir->d_inode);
|
|
|
|
return error;
|
|
}
|