Re: [PATCH v2] sysctl: treewide: constify the ctl_table argument of proc_handlers

[Kees Cook <kees@kernel.org>]

On Wed, Jun 19, 2024 at 12:09:00PM +0200, Thomas Weißschuh wrote:
> Adapt the proc_hander function signature to make it clear that handlers
> are not supposed to modify their ctl_table argument.
> 
> This is also a prerequisite to moving the static ctl_table structs into
> read-only data.
> 
> The patch was mostly generated by coccinelle with the following script:
> 
>     @@
>     identifier func, ctl, write, buffer, lenp, ppos;
>     @@
> 
>     int func(
>     - struct ctl_table *ctl,
>     + const struct ctl_table *ctl,
>       int write, void *buffer, size_t *lenp, loff_t *ppos)
>     { ... }
> 
> In addition to the scripted changes some other changes are done:
> 
> * The "typedef proc_handler" in include/linux/sysctl.h is changed to use
>   the "const ctl_table".
> 
> * The prototypes of non-static handlers in header-files are adapted
>   to match the changes of their respective definitions.
> 
> * kernel/watchdog.c: proc_watchdog_common()
>   This is called from a proc_handler itself and is als calling back
>   into another proc_handler, making it necessary to change it as part
>   of the proc_handler migration.
> 
> No functional change.
> 
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>

This looks good! I'll be glad to see these all be read-only. :)

Reviewed-by: Kees Cook <kees@kernel.org>

-- 
Kees Cook