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Thu, 31 Jul 2025 16:20:31 -0700 (PDT) From: Deepak Gupta Date: Thu, 31 Jul 2025 16:19:34 -0700 Subject: [PATCH v19 24/27] riscv: create a config for shadow stack and landing pad instr support MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20250731-v5_user_cfi_series-v19-24-09b468d7beab@rivosinc.com> References: <20250731-v5_user_cfi_series-v19-0-09b468d7beab@rivosinc.com> In-Reply-To: <20250731-v5_user_cfi_series-v19-0-09b468d7beab@rivosinc.com> To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Lorenzo Stoakes , Paul Walmsley , Palmer Dabbelt , Albert Ou , Conor Dooley , Rob Herring , Krzysztof Kozlowski , Arnd Bergmann , Christian Brauner , Peter Zijlstra , Oleg Nesterov , Eric Biederman , Kees Cook , Jonathan Corbet , Shuah Khan , Jann Horn , Conor Dooley , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Andreas Hindborg , Alice Ryhl , Trevor Gross , Benno Lossin Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, alistair.francis@wdc.com, richard.henderson@linaro.org, jim.shu@sifive.com, andybnac@gmail.com, kito.cheng@sifive.com, charlie@rivosinc.com, atishp@rivosinc.com, evan@rivosinc.com, cleger@rivosinc.com, alexghiti@rivosinc.com, samitolvanen@google.com, broonie@kernel.org, rick.p.edgecombe@intel.com, rust-for-linux@vger.kernel.org, Zong Li , Deepak Gupta X-Mailer: b4 0.13.0 X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 237FD40007 X-Stat-Signature: j5b7kieyt38dyy9duhhx9cmg78enrtz1 X-HE-Tag: 1754004032-549686 X-HE-Meta: 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 Z7cgdPMn 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: This patch creates a config for shadow stack support and landing pad instr support. Shadow stack support and landing instr support can be enabled by selecting `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. If CONFIG_RISCV_USER_CFI is selected, select `ARCH_USES_HIGH_VMA_FLAGS`, `ARCH_HAS_USER_SHADOW_STACK` and DYNAMIC_SIGFRAME for riscv. Reviewed-by: Zong Li Signed-off-by: Deepak Gupta --- arch/riscv/Kconfig | 21 +++++++++++++++++++++ arch/riscv/configs/hardening.config | 4 ++++ 2 files changed, 25 insertions(+) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 36061f4732b7..385c3d93e378 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -1161,6 +1161,27 @@ config RANDOMIZE_BASE If unsure, say N. +config RISCV_USER_CFI + def_bool n + bool "riscv userspace control flow integrity" + depends on 64BIT && $(cc-option,-mabi=lp64 -march=rv64ima_zicfiss) + depends on RISCV_ALTERNATIVE + select RISCV_SBI + select ARCH_HAS_USER_SHADOW_STACK + select ARCH_USES_HIGH_VMA_FLAGS + select DYNAMIC_SIGFRAME + 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 n. + endmenu # "Kernel features" menu "Boot options" diff --git a/arch/riscv/configs/hardening.config b/arch/riscv/configs/hardening.config new file mode 100644 index 000000000000..089f4cee82f4 --- /dev/null +++ b/arch/riscv/configs/hardening.config @@ -0,0 +1,4 @@ +# RISCV specific kernel hardening options + +# Enable control flow integrity support for usermode. +CONFIG_RISCV_USER_CFI=y -- 2.43.0