Re: [PATCH 07/12] Input: sysrq: mv sysrq into drivers/tty/sysrq.c

[Kees Cook]

On Fri, May 09, 2025 at 02:54:11PM +0200, Joel Granados wrote:
> Move both sysrq ctl_table and supported sysrq_sysctl_handler helper
> function into drivers/tty/sysrq.c. Replaced the __do_proc_dointvec in
> helper function with do_proc_dointvec as the former is local to
> kernel/sysctl.c.

nit: do_proc_dointvec_minmax

> 
> This is part of a greater effort to move ctl tables into their
> respective subsystems which will reduce the merge conflicts in
> kernel/sysctl.c.
> 
> Signed-off-by: Joel Granados <joel.granados@xxxxxxxxxx>

But yes, this looks correct.

Reviewed-by: Kees Cook <kees@xxxxxxxxxx>

-Kees

> ---
>  drivers/tty/sysrq.c | 38 ++++++++++++++++++++++++++++++++++++++
>  kernel/sysctl.c     | 30 ------------------------------
>  2 files changed, 38 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
> index 6853c4660e7c2586487fea83c12f0b7780db1ee1..8a304189749f3e33af48141a1aba5e456616c7de 100644
> --- a/drivers/tty/sysrq.c
> +++ b/drivers/tty/sysrq.c
> @@ -1119,6 +1119,44 @@ int sysrq_toggle_support(int enable_mask)
>  }
>  EXPORT_SYMBOL_GPL(sysrq_toggle_support);
>  
> +static int sysrq_sysctl_handler(const struct ctl_table *table, int write,
> +				void *buffer, size_t *lenp, loff_t *ppos)
> +{
> +	int tmp, ret;
> +	struct ctl_table t = *table;
> +
> +	tmp = sysrq_mask();
> +	t.data = &tmp;
> +
> +	ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
> +
> +	if (ret || !write)
> +		return ret;
> +
> +	if (write)
> +		sysrq_toggle_support(tmp);
> +
> +	return 0;
> +}
> +
> +static const struct ctl_table sysrq_sysctl_table[] = {
> +	{
> +		.procname	= "sysrq",
> +		.data		= NULL,
> +		.maxlen		= sizeof(int),
> +		.mode		= 0644,
> +		.proc_handler	= sysrq_sysctl_handler,
> +	},
> +};
> +
> +static int __init init_sysrq_sysctl(void)
> +{
> +	register_sysctl_init("kernel", sysrq_sysctl_table);
> +	return 0;
> +}
> +
> +subsys_initcall(init_sysrq_sysctl);
> +
>  static int __sysrq_swap_key_ops(u8 key, const struct sysrq_key_op *insert_op_p,
>  				const struct sysrq_key_op *remove_op_p)
>  {
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index febf328054aa5a7b2462a256598f86f5ded87c90..ebcc7d75acd9fecbf3c10f31480c3cb6960cb53e 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -31,7 +31,6 @@
>  #include <linux/kernel.h>
>  #include <linux/kobject.h>
>  #include <linux/net.h>
> -#include <linux/sysrq.h>
>  #include <linux/highuid.h>
>  #include <linux/writeback.h>
>  #include <linux/ratelimit.h>
> @@ -964,26 +963,6 @@ int proc_dou8vec_minmax(const struct ctl_table *table, int write,
>  }
>  EXPORT_SYMBOL_GPL(proc_dou8vec_minmax);
>  
> -#ifdef CONFIG_MAGIC_SYSRQ
> -static int sysrq_sysctl_handler(const struct ctl_table *table, int write,
> -				void *buffer, size_t *lenp, loff_t *ppos)
> -{
> -	int tmp, ret;
> -
> -	tmp = sysrq_mask();
> -
> -	ret = __do_proc_dointvec(&tmp, table, write, buffer,
> -			       lenp, ppos, NULL, NULL);
> -	if (ret || !write)
> -		return ret;
> -
> -	if (write)
> -		sysrq_toggle_support(tmp);
> -
> -	return 0;
> -}
> -#endif
> -
>  static int __do_proc_doulongvec_minmax(void *data,
>  		const struct ctl_table *table, int write,
>  		void *buffer, size_t *lenp, loff_t *ppos,
> @@ -1612,15 +1591,6 @@ static const struct ctl_table kern_table[] = {
>  		.proc_handler	= proc_dostring,
>  	},
>  #endif
> -#ifdef CONFIG_MAGIC_SYSRQ
> -	{
> -		.procname	= "sysrq",
> -		.data		= NULL,
> -		.maxlen		= sizeof (int),
> -		.mode		= 0644,
> -		.proc_handler	= sysrq_sysctl_handler,
> -	},
> -#endif
>  #ifdef CONFIG_PROC_SYSCTL
>  	{
>  		.procname	= "cad_pid",
> 
> -- 
> 2.47.2
> 
> 

-- 
Kees Cook