2020-01-09 08:16:01

by Christophe Leroy

Subject: [PATCH] init: fix misleading "This architecture does not have kernel memory protection" message

This message leads to think that memory protection is not implemented
for the said architecture, whereas absence of CONFIG_STRICT_KERNEL_RWX
only means that memory protection has not been selected at
compile time.

Don't print this message when CONFIG_ARCH_HAS_STRICT_KERNEL_RWX is
selected by the architecture. Instead, print "Kernel memory protection
not selected by kernel config."

Signed-off-by: Christophe Leroy <[email protected]>
---
init/main.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/init/main.c b/init/main.c
index 2cd736059416..fd31b15cc910 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1090,6 +1090,11 @@ static void mark_readonly(void)
} else
pr_info("Kernel memory protection disabled.\n");
}
+#elif defined(CONFIG_ARCH_HAS_STRICT_KERNEL_RWX)
+static inline void mark_readonly(void)
+{
+ pr_warn("Kernel memory protection not selected by kernel config.\n");
+}
#else
static inline void mark_readonly(void)
{
--
2.13.3

2020-01-10 05:15:05

by Kees Cook

Subject: Re: [PATCH] init: fix misleading "This architecture does not have kernel memory protection" message

On Thu, Jan 09, 2020 at 08:15:01AM +0000, Christophe Leroy wrote:
> This message leads to think that memory protection is not implemented
> for the said architecture, whereas absence of CONFIG_STRICT_KERNEL_RWX
> only means that memory protection has not been selected at
> compile time.
>
> Don't print this message when CONFIG_ARCH_HAS_STRICT_KERNEL_RWX is
> selected by the architecture. Instead, print "Kernel memory protection
> not selected by kernel config."
>
> Signed-off-by: Christophe Leroy <[email protected]>

Oh, yes, I like this. Should the message include a hint to the config
name?

Regardless:

Acked-by: Kees Cook <[email protected]>

-Kees

> ---
> init/main.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/init/main.c b/init/main.c
> index 2cd736059416..fd31b15cc910 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -1090,6 +1090,11 @@ static void mark_readonly(void)
> } else
> pr_info("Kernel memory protection disabled.\n");
> }
> +#elif defined(CONFIG_ARCH_HAS_STRICT_KERNEL_RWX)
> +static inline void mark_readonly(void)
> +{
> + pr_warn("Kernel memory protection not selected by kernel config.\n");
> +}
> #else
> static inline void mark_readonly(void)
> {
> --
> 2.13.3
>

--
Kees Cook