Re: [PATCH] debugfs: only accept read attributes for blobs

Greg Kroah-Hartman
2021-05-04T13:00:00Z

On Tue, May 04, 2021 at 02:17:20PM +0200, Wolfram Sang wrote:
> Blobs can only be read. So, keep only 'read' file attributes because the
> others will not work and only confuse users.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> ---
>
> I was confused for a second, thinking blobs can be written to. I will
> fix the few in-kernel users doing it wrong seperately.
>
> fs/debugfs/file.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
> index 686e0ad28788..d6aa6e04b7af 100644
> --- a/fs/debugfs/file.c
> +++ b/fs/debugfs/file.c
> @@ -890,7 +890,8 @@ static const struct file_operations fops_blob = {
> /**
> * debugfs_create_blob - create a debugfs file that is used to read a binary blob
> * @name: a pointer to a string containing the name of the file to create.
> - * @mode: the permission that the file should have
> + * @mode: the read permission that the file should have (other permissions are
> + * masked out)
> * @parent: a pointer to the parent dentry for this file. This should be a
> * directory dentry if set. If this parameter is %NULL, then the
> * file will be created in the root of the debugfs filesystem.
> @@ -914,7 +915,7 @@ struct dentry *debugfs_create_blob(const char *name, umode_t mode,
> struct dentry *parent,
> struct debugfs_blob_wrapper *blob)
> {
> - return debugfs_create_file_unsafe(name, mode, parent, blob, &fops_blob);
> + return debugfs_create_file_unsafe(name, mode & S_IRUGO, parent, blob, &fops_blob);

Can you use an octal number for this? I think checkpatch.pl will
complain here.

thanks,

greg k-h