Re: [PATCH v2] syscall_user_dispatch: Use CONFIG_SYSCTL for sysctl guard

[Randy Dunlap]

On 8/22/26 12:23 AM, Karl Mehltretter wrote:
> Commit 8d75c338f0bc ("sysctl: remove CONFIG_PROC_SYSCTL, it just mirrors
> CONFIG_SYSCTL") removed CONFIG_PROC_SYSCTL, but the sysctl added by
> commit 5b6e32ba7b59 ("syscall_user_dispatch: Add
> kernel.syscall_user_dispatch sysctl") is still guarded by it. Now that
> both commits are merged, kernel.syscall_user_dispatch is no longer
> registered.
> 
> syscall_user_dispatch_allowed defaults to true. SUD therefore remains
> available, but administrators cannot disable new activations.
> 
> Use CONFIG_SYSCTL for the guard and documentation.
> 
> Fixes: 5b6e32ba7b59 ("syscall_user_dispatch: Add kernel.syscall_user_dispatch sysctl")
> Assisted-by: Codex:gpt-5.6-sol
> Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>
> Reviewed-by: Joel Granados <joel.granados@xxxxxxxxxx>
> Signed-off-by: Karl Mehltretter <kmehltretter@xxxxxxxxx>

Acked-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Thanks.

> ---
> Changes in v2:
>   - Reword changelog and rebase onto mainline now that both commits
>     are merged there (v7.2 is unaffected, it has neither commit).
>   - Collected Acked-by/Reviewed-by tags from v1. No code change.
> 
> v1: https://lore.kernel.org/all/20260813062039.14567-1-kmehltretter@xxxxxxxxx/
> 
>  Documentation/admin-guide/sysctl/kernel.rst | 2 +-
>  kernel/entry/syscall_user_dispatch.c        | 4 ++--
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
> index b6328cd0f43e..ffea61d448eb 100644
> --- a/Documentation/admin-guide/sysctl/kernel.rst
> +++ b/Documentation/admin-guide/sysctl/kernel.rst
> @@ -1416,7 +1416,7 @@ Controls whether userspace may arm Syscall User Dispatch via
>    ==  ===================================================================
>  
>  Only present when the kernel is built with ``CONFIG_SYSCALL_USER_DISPATCH``
> -and ``CONFIG_PROC_SYSCTL``.
> +and ``CONFIG_SYSCTL``.
>  
>  
>  sysctl_writes_strict
> diff --git a/kernel/entry/syscall_user_dispatch.c b/kernel/entry/syscall_user_dispatch.c
> index 2002c7aae435..59c861866941 100644
> --- a/kernel/entry/syscall_user_dispatch.c
> +++ b/kernel/entry/syscall_user_dispatch.c
> @@ -178,7 +178,7 @@ int syscall_user_dispatch_set_config(struct task_struct *task, unsigned long siz
>  					      (char __user *)(uintptr_t)cfg.selector);
>  }
>  
> -#ifdef CONFIG_PROC_SYSCTL
> +#ifdef CONFIG_SYSCTL
>  static const struct ctl_table syscall_user_dispatch_sysctls[] = {
>  	{
>  		.procname	= "syscall_user_dispatch",
> @@ -195,4 +195,4 @@ static int __init syscall_user_dispatch_sysctl_init(void)
>  	return 0;
>  }
>  late_initcall(syscall_user_dispatch_sysctl_init);
> -#endif /* CONFIG_PROC_SYSCTL */
> +#endif /* CONFIG_SYSCTL */
> 
> base-commit: 26260251022fbc2f248a3d747a9b2b961b18d2d8

-- 
~Randy