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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id j3-20020a170903024300b001624965d83bsm617411plh.228.2022.06.15.22.36.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Jun 2022 22:36:55 -0700 (PDT) Date: Wed, 15 Jun 2022 22:36:54 -0700 From: Kees Cook To: Dao Lu Cc: linux-kernel@vger.kernel.org, Paul Walmsley , Palmer Dabbelt , Albert Ou , Ard Biesheuvel , Guo Ren , Geert Uytterhoeven , Arnd Bergmann , Tong Tiangen , Mark Rutland , Changbin Du , Vincent Chen , "open list:RISC-V ARCHITECTURE" , "open list:EXTENSIBLE FIRMWARE INTERFACE (EFI)" Subject: Re: [PATCH] arch/riscv: Add support for STACKLEAK gcc plugin Message-ID: <202206152234.DE7FC51F9@keescook> References: <20220615213834.3116135-1-daolu@rivosinc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220615213834.3116135-1-daolu@rivosinc.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 15, 2022 at 02:38:29PM -0700, Dao Lu wrote: > This adds support for STACKLEAK gcc plugin to ricv by implementing typo: riscv > stackleak_check_alloca, based heavily on the arm64 version, and adding stackleak_check_alloca does not exist. Was this maybe from an older commit log? > the two helpers used by the stackleak common code: > current_top_of_stack() and on_thread_stack(). This also adds the missing > helper functions for riscv, on_stack() and on_task_stack(). > Additionally, this disables the plugin for EFI stub code for riscv. I can't speak to the arch-specific bits here, but if this passes the current LKDTM tests, then that should be a good indication that it's working. :) > > Signed-off-by: Dao Lu > --- > arch/riscv/Kconfig | 1 + > arch/riscv/include/asm/processor.h | 18 ++++++++++++++++++ > arch/riscv/include/asm/stacktrace.h | 27 +++++++++++++++++++++++++++ > arch/riscv/kernel/entry.S | 3 +++ > drivers/firmware/efi/libstub/Makefile | 2 +- > 5 files changed, 50 insertions(+), 1 deletion(-) > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > index c22f58155948..22aa146acd25 100644 > --- a/arch/riscv/Kconfig > +++ b/arch/riscv/Kconfig > @@ -80,6 +80,7 @@ config RISCV > select HAVE_ARCH_MMAP_RND_BITS if MMU > select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT > select HAVE_ARCH_SECCOMP_FILTER > + select HAVE_ARCH_STACKLEAK > select HAVE_ARCH_TRACEHOOK > select HAVE_ARCH_TRANSPARENT_HUGEPAGE if 64BIT && MMU > select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE > diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h > index 21c8072dce17..3a7505ab7f58 100644 > --- a/arch/riscv/include/asm/processor.h > +++ b/arch/riscv/include/asm/processor.h > @@ -85,6 +85,24 @@ int riscv_of_parent_hartid(struct device_node *node); > extern void riscv_fill_hwcap(void); > extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); > > +/* > + * For CONFIG_GCC_PLUGIN_STACKLEAK > + * > + * These need to be macros because otherwise we get stuck in a nightmare > + * of header definitions for the use of task_stack_page. > + */ > + > +struct stack_info { > + unsigned long low; > + unsigned long high; > +}; > + > +/* > + * The top of the current task's task stack > + */ > +#define current_top_of_stack() ((unsigned long)current->stack + THREAD_SIZE) > +#define on_thread_stack() (on_task_stack(current, current_stack_pointer, 1, NULL)) > + > #endif /* __ASSEMBLY__ */ > > #endif /* _ASM_RISCV_PROCESSOR_H */ > diff --git a/arch/riscv/include/asm/stacktrace.h b/arch/riscv/include/asm/stacktrace.h > index 3450c1912afd..afb66b677b6a 100644 > --- a/arch/riscv/include/asm/stacktrace.h > +++ b/arch/riscv/include/asm/stacktrace.h > @@ -16,4 +16,31 @@ extern void notrace walk_stackframe(struct task_struct *task, struct pt_regs *re > extern void dump_backtrace(struct pt_regs *regs, struct task_struct *task, > const char *loglvl); > > +static inline bool on_stack(unsigned long sp, unsigned long size, > + unsigned long low, unsigned long high, > + struct stack_info *info) > +{ > + if (!low) > + return false; > + > + if (sp < low || sp + size < sp || sp + size > high) > + return false; > + > + if (info) { > + info->low = low; > + info->high = high; > + } > + return true; > +} > + > +static inline bool on_task_stack(const struct task_struct *tsk, > + unsigned long sp, unsigned long size, > + struct stack_info *info) > +{ > + unsigned long low = (unsigned long)task_stack_page(tsk); > + unsigned long high = low + THREAD_SIZE; > + > + return on_stack(sp, size, low, high, info); > +} > + > #endif /* _ASM_RISCV_STACKTRACE_H */ > diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S > index 2e5b88ca11ce..65d441cb560f 100644 > --- a/arch/riscv/kernel/entry.S > +++ b/arch/riscv/kernel/entry.S > @@ -264,6 +264,9 @@ ret_from_exception: > bnez s0, resume_kernel > > resume_userspace: > +#ifdef CONFIG_GCC_PLUGIN_STACKLEAK > + call stackleak_erase > +#endif > /* Interrupts must be disabled here so flags are checked atomically */ > REG_L s0, TASK_TI_FLAGS(tp) /* current_thread_info->flags */ > andi s1, s0, _TIF_WORK_MASK > diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile > index d0537573501e..5e1fc4f82883 100644 > --- a/drivers/firmware/efi/libstub/Makefile > +++ b/drivers/firmware/efi/libstub/Makefile > @@ -25,7 +25,7 @@ cflags-$(CONFIG_ARM) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ > -fno-builtin -fpic \ > $(call cc-option,-mno-single-pic-base) > cflags-$(CONFIG_RISCV) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ > - -fpic > + -fpic $(DISABLE_STACKLEAK_PLUGIN) > > cflags-$(CONFIG_EFI_GENERIC_STUB) += -I$(srctree)/scripts/dtc/libfdt > > -- > 2.25.1 > -- Kees Cook