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J . Lu" , Yu-cheng Yu , linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, libc-alpha@sourceware.org, Mark Brown Subject: [PATCH v6 0/4] arm64: Enable BTI for the executable as well as the interpreter Date: Thu, 16 Sep 2021 16:28:17 +0100 Message-Id: <20210916152821.1153-1-broonie@kernel.org> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2343; h=from:subject; bh=FpfW2dml9iwXK4/Wly3stSwGR4U67dk+Puq8J5H2csI=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBhQ2KREZKgPv/EBvhKPZFFrjL0WsWLYD7CC1vAsC9i PARhInOJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCYUNikQAKCRAk1otyXVSH0P/1B/ 0cCj/YTkZ+DVhsjUTyg8TLY5ptwj+JU6OAT83cPtOtYWX2g0NWFIa/SZWmIgIIjniBzyaBulr/74fw RHfTK57MNOQkeXBg+c9aKnfKDGwcPdlll8J6iAHW/FDyEGVpHh8nANsQAKjSzhPm6t2SZca3suGdSH vue978zca/IX2R/L009gybaG+3x2s1PPej3mOak1e5Q4rzF5IoACW6loM1b9Q3smpGJuCH4cXRUmtA 4W1PFvc1lyyOx+HtSP/I/lX+QJXrSorx6PqdXYw/Xbz1540uW4D1SHKRNTSTzUXwnjMGIr5Vu28A/d eUT9a/QpSYKAy3qt5qYjnkY+PclYfq X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org Deployments of BTI on arm64 have run into issues interacting with systemd's MemoryDenyWriteExecute feature. Currently for dynamically linked executables the kernel will only handle architecture specific properties like BTI for the interpreter, the expectation is that the interpreter will then handle any properties on the main executable. For BTI this means remapping the executable segments PROT_EXEC | PROT_BTI. This interacts poorly with MemoryDenyWriteExecute since that is implemented using a seccomp filter which prevents setting PROT_EXEC on already mapped memory and lacks the context to be able to detect that memory is already mapped with PROT_EXEC. This series resolves this by handling the BTI property for both the interpreter and the main executable. This does mean that we may get more code with BTI enabled if running on a system without BTI support in the dynamic linker, this is expected to be a safe configuration and testing seems to confirm that. It also reduces the flexibility userspace has to disable BTI but it is expected that for cases where there are problems which require BTI to be disabled it is more likely that it will need to be disabled on a system level. v6: - Rebase onto v5.15-rc1. v5: - Rebase onto v5.14-rc2. - Tweak changelog on patch 1. - Use the helper for interpreter/executable flag in elf.h as well. v4: - Rebase onto v5.14-rc1. v3: - Fix passing of properties for parsing by the main executable. - Drop has_interp from arch_parse_elf_property(). - Coding style tweaks. v2: - Add a patch dropping has_interp from arch_adjust_elf_prot() - Fix bisection issue with static executables on arm64 in the first patch. Mark Brown (4): elf: Allow architectures to parse properties on the main executable arm64: Enable BTI for main executable as well as the interpreter elf: Remove has_interp property from arch_adjust_elf_prot() elf: Remove has_interp property from arch_parse_elf_property() arch/arm64/include/asm/elf.h | 14 ++++++++++++-- arch/arm64/kernel/process.c | 16 +++------------- fs/binfmt_elf.c | 29 ++++++++++++++++++++--------- include/linux/elf.h | 8 +++++--- 4 files changed, 40 insertions(+), 27 deletions(-) base-commit: 6880fa6c56601bb8ed59df6c30fd390cc5f6dd8f -- 2.20.1