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Wed, 15 Oct 2025 11:14:39 -0700 (PDT) From: Deepak Gupta Date: Wed, 15 Oct 2025 11:13:57 -0700 Subject: [PATCH v21 25/28] 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: <20251015-v5_user_cfi_series-v21-25-6a07856e90e7@rivosinc.com> References: <20251015-v5_user_cfi_series-v21-0-6a07856e90e7@rivosinc.com> In-Reply-To: <20251015-v5_user_cfi_series-v21-0-6a07856e90e7@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-Stat-Signature: fz7qoi49ebq36xk3uzcsqd9jc4q9ogyx X-Rspamd-Queue-Id: B7D6316000E X-Rspamd-Server: rspam09 X-HE-Tag: 1760552081-714614 X-HE-Meta: U2FsdGVkX19cdKgp3Z3eBu4YHRTFSz/PiYPSyQDipeZJkJUHEIX6XjR4YU5BZJzMHrnp/Yf3gllHjDxnr6yZopUpVUwSWAY45dcmjfY3AYT7xBDDx1+nyNo9ErMjuRJen0KMOLzs2pOrUziRaXWyawMqlT/rJWFhACrJkoVieXk+pIiRI2pNmfrRN6ETGKhYPD1rn+NSxK2V0fUNq8cfEQfzFhvGgy1VXPgmLoRbQ9YI7jzWExvwydxrzc8IiSPrkzw9VDesDnRcgd1ZggvSo/xWd5Fux+RJVBhR2eP/vW11GDV/U1Ah7bXSDCiCA0gp7lIgZ0oo/CefnUEPaVMRtakX/j6K4acJwEs7GJBF+h88NKCl8Gbqv/rA/s9jHK6Pza3d8W26oSkirRlrFQxmfrJiIHDxBwuNoSNRbJMqhtRLqH2qt0stJPLEBmCtHxH/AzYccEciCJNLrVgBch1VAjraLCPwkrxQgVTh7GpUSZ4qMmKId9nBnvGfMGbBxTC+F9RwIrbyH+vhjHjfLg7k654QFhckrH5MWEeIA+vD/EbPKx/Z7nJa2+YPxa0PZPSYfIwGR9NkfgDoNm7DDDq2XX13m9Pl6tdMrGOMrUb/H2JzJ/Er6kJU6kXJtPivMIMqPOWUzJUa+7JSCBqGJAt+QM60VcXfthifyLUoUamlEBMVUgGEQiUEN1Ux2hraqjO6zP2EXC/QUtXsLfjHEiMnstSoc0+7VMhlhqTHeyS7sBo0fFt1d3cmJV1hmM+IYV/KbRXTMw3gTCeZgbmqf/xdKoRazxEDTuW5fmxcXI+VVgYbkRRv5AnczHU3KVHOpCmn5G5Wgy0owWcIZouWcqfl1HHlavuGAVkSSlBfFSsKhTAkvR+xm9vBqRAtrijll+9sic6BJOwLRhf+dolx7qMaXBUGI8aep4DMbfyHKWJz7NGcgCkLxmN4wBpd8dEintWPQrc3cO1AullVt5QJm4+ VGFIfH0T TF1bRLRV7eiNiSXwoFFrvlc12Az8Phlez7XAlDbTsI6IsC8BMHH3Y63FyyO8qUOmtxKRToVJcvYg9/povo7zIKDXVd/wm7YQLpk4cgrBvi5japyq24pfegoX96k3YZ2ZxaijT/MuEcKx93Jx0CTVLhnc6E1NQbYX1/J+s+rvdJrRXYN4c+rOMZbguAQoXCJ78rJHae3BwqAmmshhYmoZaqDtkVoy9UWpfl8+PvK/2N4GFy17NeT/0ZsK8HgxKWiE0gsnIRv7rNcS2LCO+WZ+Y/RNCKakTWzW7Yky2kHn5ROKGjePWwoO2omIDk5VEPgxXLODvE3rdCRV6NmO2KSBUiLnJqzUnEzFeioDYMT/wP6LYEfbKx6B5KWpefhkKg5Oi0PRRP5LuMEhXNsnkqYIcPHm8f0jzxgVhW+M8r/Fsbzk0YmESjIhs4Gf1D1Pg81gkQBYCjV/UwDngQ16fTqIdjBWPo9DTuDEXaylf 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 0c6038dc5dfd..aed033e2b526 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -1146,6 +1146,27 @@ config RANDOMIZE_BASE If unsure, say N. +config RISCV_USER_CFI + def_bool y + 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