From: Tong Tiangen <tongtiangen@huawei.com>
Date: Fri, 2 Jul 2021 04:54:21 +0000 (+0000)
Subject: riscv: Implement thread_struct whitelist for hardened usercopy
X-Git-Tag: v5.15~359^2~18
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=13e47bebbe83f58ddc41d2987567e97c5068a1ec;p=platform%2Fkernel%2Flinux-starfive.git

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 <tongtiangen@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
---

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 8fcceb8..1af859b 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -72,6 +72,7 @@ config RISCV
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE if 64BIT && MMU
+	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
 	select HAVE_ARCH_VMAP_STACK if MMU && 64BIT
 	select HAVE_ASM_MODVERSIONS
 	select HAVE_CONTEXT_TRACKING
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index 021ed64..46b492c 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,	\
 }