From: Deepak Gupta debug@rivosinc.com
This patch selects config shadow stack support and landing pad instr support. Shadow stack support and landing instr support is hidden behind `CONFIG_RISCV_USER_CFI`. Selecting `CONFIG_RISCV_USER_CFI` wires up path to enumerate CPU support and if cpu support exists, kernel will support cpu assisted user mode cfi.
Signed-off-by: Deepak Gupta debug@rivosinc.com --- arch/riscv/Kconfig | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 9d386e9edc45..437b2f9abf3e 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -163,6 +163,7 @@ config RISCV select SYSCTL_EXCEPTION_TRACE select THREAD_INFO_IN_TASK select TRACE_IRQFLAGS_SUPPORT + select RISCV_USER_CFI select UACCESS_MEMCPY if !MMU select ZONE_DMA32 if 64BIT
@@ -182,6 +183,20 @@ config HAVE_SHADOW_CALL_STACK # https://github.com/riscv-non-isa/riscv-elf-psabi-doc/commit/a484e843e6eeb51f... depends on $(ld-option,--no-relax-gp)
+config RISCV_USER_CFI + bool "riscv userspace control flow integrity" + help + Provides CPU assisted control flow integrity to userspace tasks. + Control flow integrity is provided by implementing shadow stack for + backward edge and indirect branch tracking for forward edge in program. + Shadow stack protection is a hardware feature that detects function + return address corruption. This helps mitigate ROP attacks. + Indirect branch tracking enforces that all indirect branches must land + on a landing pad instruction else CPU will fault. This mitigates against + JOP / COP attacks. Applications must be enabled to use it, and old user- + space does not get protection "for free". + default y + config ARCH_MMAP_RND_BITS_MIN default 18 if 64BIT default 8