2021-07-02 04:47:30

by Tong Tiangen

Subject: [PATCH -next] riscv: Implement thread_struct whitelist for hardened usercopy

This whitelists the FPU register state portion of the thread_struct for
copying to userspace, instead of the default entire struct.

Signed-off-by: Tong Tiangen <[email protected]>
---
arch/riscv/Kconfig | 1 +
arch/riscv/include/asm/processor.h | 8 ++++++++
2 files changed, 9 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 821081bdb8b8..5c26c0726944 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -70,6 +70,7 @@ config RISCV
select HAVE_ARCH_MMAP_RND_BITS if MMU
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_TRACEHOOK
+ select HAVE_ARCH_THREAD_STRUCT_WHITELIST
select HAVE_ASM_MODVERSIONS
select HAVE_CONTEXT_TRACKING
select HAVE_DEBUG_KMEMLEAK
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index 021ed64ee608..46b492c78cbb 100644
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -37,6 +37,14 @@ struct thread_struct {
unsigned long bad_cause;
};

+/* Whitelist the fstate from the task_struct for hardened usercopy */
+static inline void arch_thread_struct_whitelist(unsigned long *offset,
+ unsigned long *size)
+{
+ *offset = offsetof(struct thread_struct, fstate);
+ *size = sizeof_field(struct thread_struct, fstate);
+}
+
#define INIT_THREAD { \
.sp = sizeof(init_stack) + (long)&init_stack, \
}
--
2.25.1

2021-08-04 05:01:51

by Palmer Dabbelt

Subject: Re: [PATCH -next] riscv: Implement thread_struct whitelist for hardened usercopy

On Thu, 01 Jul 2021 21:54:21 PDT (-0700), [email protected] wrote:
> This whitelists the FPU register state portion of the thread_struct for
> copying to userspace, instead of the default entire struct.
>
> Signed-off-by: Tong Tiangen <[email protected]>
> ---
> arch/riscv/Kconfig | 1 +
> arch/riscv/include/asm/processor.h | 8 ++++++++
> 2 files changed, 9 insertions(+)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 821081bdb8b8..5c26c0726944 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -70,6 +70,7 @@ config RISCV
> select HAVE_ARCH_MMAP_RND_BITS if MMU
> select HAVE_ARCH_SECCOMP_FILTER
> select HAVE_ARCH_TRACEHOOK
> + select HAVE_ARCH_THREAD_STRUCT_WHITELIST
> select HAVE_ASM_MODVERSIONS
> select HAVE_CONTEXT_TRACKING
> select HAVE_DEBUG_KMEMLEAK
> diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
> index 021ed64ee608..46b492c78cbb 100644
> --- a/arch/riscv/include/asm/processor.h
> +++ b/arch/riscv/include/asm/processor.h
> @@ -37,6 +37,14 @@ struct thread_struct {
> unsigned long bad_cause;
> };
>
> +/* Whitelist the fstate from the task_struct for hardened usercopy */
> +static inline void arch_thread_struct_whitelist(unsigned long *offset,
> + unsigned long *size)
> +{
> + *offset = offsetof(struct thread_struct, fstate);
> + *size = sizeof_field(struct thread_struct, fstate);
> +}
> +
> #define INIT_THREAD { \
> .sp = sizeof(init_stack) + (long)&init_stack, \
> }

Thanks, this is on for-next.