On Fri, 2022-11-18 at 09:07 -0600, Nathan Lynch wrote:
> CONFIG_PPC_RTAS_FILTER has been optional but default-enabled since
> its
> introduction. It's been enabled in enterprise distro kernels for a
> while without causing ABI breakage that wasn't easily fixed, and it
> prevents harmful abuses of the rtas syscall.
>
> Let's make it unconditional.
>
> Signed-off-by: Nathan Lynch <nath...@linux.ibm.com>
Agreed.
Reviewed-by: Andrew Donnellan <a...@linux.ibm.com>
> ---
> arch/powerpc/Kconfig | 13 -------------
> arch/powerpc/kernel/rtas.c | 16 ----------------
> 2 files changed, 29 deletions(-)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 2ca5418457ed..8092915a4e9b 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -1012,19 +1012,6 @@ config PPC_SECVAR_SYSFS
> read/write operations on these variables. Say Y if you have
> secure boot enabled and want to expose variables to
> userspace.
>
> -config PPC_RTAS_FILTER
> - bool "Enable filtering of RTAS syscalls"
> - default y
> - depends on PPC_RTAS
> - help
> - The RTAS syscall API has security issues that could be used
> to
> - compromise system integrity. This option enforces
> restrictions on the
> - RTAS calls and arguments passed by userspace programs to
> mitigate
> - these issues.
> -
> - Say Y unless you know what you are doing and the filter is
> causing
> - problems for you.
> -
> endmenu
>
> config ISA_DMA_API
> diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
> index c3142d352f41..3929bcea92c0 100644
> --- a/arch/powerpc/kernel/rtas.c
> +++ b/arch/powerpc/kernel/rtas.c
> @@ -1051,8 +1051,6 @@ noinstr struct pseries_errorlog
> *get_pseries_errorlog(struct rtas_error_log *log
> return NULL;
> }
>
> -#ifdef CONFIG_PPC_RTAS_FILTER
> -
> /*
> * The sys_rtas syscall, as originally designed, allows root to pass
> * arbitrary physical addresses to RTAS calls. A number of RTAS
> calls
> @@ -1201,20 +1199,6 @@ static void __init
> rtas_syscall_filter_init(void)
> rtas_filters[i].token =
> rtas_token(rtas_filters[i].name);
> }
>
> -#else
> -
> -static bool block_rtas_call(int token, int nargs,
> - struct rtas_args *args)
> -{
> - return false;
> -}
> -
> -static void __init rtas_syscall_filter_init(void)
> -{
> -}
> -
> -#endif /* CONFIG_PPC_RTAS_FILTER */
> -
> /* We assume to be passed big endian arguments */
> SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs)
> {
--
Andrew Donnellan OzLabs, ADL Canberra
a...@linux.ibm.com IBM Australia Limited
