Re: [PATCH v2 3/3] initramfs: introduce do_readxattrs()

[Roberto Sassu]

On 5/10/2019 11:33 PM, Jann Horn wrote:
> On Thu, May 09, 2019 at 01:24:20PM +0200, Roberto Sassu wrote:
> > This patch adds support for an alternative method to add xattrs to files in
> > the rootfs filesystem. Instead of extracting them directly from the ram
> > disk image, they are extracted from a regular file called .xattr-list, that
> > can be added by any ram disk generator available today.
> [...]
> > +struct path_hdr {
> > +	char p_size[10]; /* total size including p_size field */
> > +	char p_data[];  /* <path>\0<xattrs> */
> > +};
> > +
> > +static int __init do_readxattrs(void)
> > +{
> > +	struct path_hdr hdr;
> > +	char str[sizeof(hdr.p_size) + 1];
> > +	unsigned long file_entry_size;
> > +	size_t size, name_buf_size, total_size;
> > +	struct kstat st;
> > +	int ret, fd;
> > +
> > +	ret = vfs_lstat(XATTR_LIST_FILENAME, &st);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	total_size = st.size;
> > +
> > +	fd = ksys_open(XATTR_LIST_FILENAME, O_RDONLY, 0);
> > +	if (fd < 0)
> > +		return fd;
> > +
> > +	while (total_size) {
> > +		size = ksys_read(fd, (char *)&hdr, sizeof(hdr));
> [...]
> > +	ksys_close(fd);
> > +
> > +	if (ret < 0)
> > +		error("Unable to parse xattrs");
> > +
> > +	return ret;
> > +}
>
> Please use something like filp_open()+kernel_read()+fput() instead of
> ksys_open()+ksys_read()+ksys_close(). I understand that some of the init
> code needs to use the syscall wrappers because no equivalent VFS
> functions are available, but please use the VFS functions when that's
> easy to do.

Ok. Thanks for the suggestion.

Roberto

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