Re: [PATCH v10 8/9] proc: use human-readable values for hidehid

Eric W. Biederman
2020-04-02T16:08:24Z

Alexey Gladkov <gladkov.alexey@gmail.com> writes:

> The hidepid parameter values are becoming more and more and it becomes
> difficult to remember what each new magic number means.

In principle I like this change. In practice I think you have just
broken ABI compatiblity with the new mount ABI.

In particular the following line seems broken.

> diff --git a/fs/proc/root.c b/fs/proc/root.c
> index dbcd96f07c7a..ba782d6e6197 100644
> --- a/fs/proc/root.c
> +++ b/fs/proc/root.c
> @@ -45,7 +45,7 @@ enum proc_param {
>
> static const struct fs_parameter_spec proc_fs_parameters[] = {
> fsparam_u32("gid", Opt_gid),
> - fsparam_u32("hidepid", Opt_hidepid),
> + fsparam_string("hidepid", Opt_hidepid),
> fsparam_string("subset", Opt_subset),
> {}
> };

As I read fs_parser.c fs_param_is_u32 handles string inputs and turns them
into numbers, and it handles binary numbers. However fs_param_is_string
appears to only handle strings. It appears to have not capacity to turn
raw binary numbers into strings.

So I think we probably need to fix fs_param_is_string to raw binary
numbers before we can safely make this change to fs/proc/root.c

David am I reading the fs_parser.c code correctly? If I am are you ok
with a change like the above?

Eric