Re: [PATCH v5 2/4] ima: use fs method to read integrity data

[Christoph Hellwig <hch@lst.de>]

On Thu, Aug 10, 2017 at 07:41:45PM -0400, Mimi Zohar wrote:
> From: Christoph Hellwig <hch@lst.de>
> 
> Add a new ->integrity_read file operation to read data for integrity
> hash collection.  This is defined to be equivalent to ->read_iter,
> except that it will be called with the i_rwsem held exclusively.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Btw, most of this is yours now, feel free to take over the authorship
with a little credit to me for the initial patch if you want.

> Cc: Matthew Garrett <matthew.garrett@nebula.com>

I don't think that will reach Matthew anymore :)

> -static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
> -		size_t count, loff_t *ppos)
> +static ssize_t efivarfs_file_read_iter(struct kiocb *iocb,
> +				       struct iov_iter *iter)

The efivars switch to read_iter should be a separate patch before
this one.

>  /**
> + * simple_read_iter_from_buffer - copy data from the buffer to user space
> + * @iocb: struct containing the file, the current position and other info
> + * @to: the user space buffer to read to
> + * @from: the buffer to read from
> + * @available: the size of the buffer
> + *
> + * The simple_read_iter_from_buffer() function reads up to @available bytes
> + * from the current buffer into the user space buffer.
> + *
> + * On success, the current buffer offset is advanced by the number of bytes
> + * read, or a negative value is returned on error.
> + **/
> +ssize_t simple_read_iter_from_buffer(struct kiocb *iocb, struct iov_iter *to,
> +				     const void *from, size_t available)

The addition of simple_read_iter_from_buffer should be another separate
patch, before efivars starts using it.