From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by sourceware.org (Postfix) with ESMTPS id E406B3848400 for ; Fri, 4 Jun 2021 11:25:04 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org E406B3848400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7FBC2613FE; Fri, 4 Jun 2021 11:25:03 +0000 (UTC) From: Mark Brown To: Catalin Marinas , Will Deacon Cc: Szabolcs Nagy , Jeremy Linton , Dave Martin , "H . J . Lu" , Yu-cheng Yu , linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, libc-alpha@sourceware.org, Mark Brown Subject: [PATCH v2 0/3] arm64: Enable BTI for the executable as well as the interpreter Date: Fri, 4 Jun 2021 12:24:47 +0100 Message-Id: <20210604112450.13344-1-broonie@kernel.org> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1935; h=from:subject; bh=+xnPy6vKSA4JZpieqy9rOye/hz55CPiRF8qm7EZ7dLQ=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBgug1/P0DyUOyeqjIBzn0tFkh5xzY2HcRp/M4GxMOy 7l9nn6GJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCYLoNfwAKCRAk1otyXVSH0M4JB/ oCYpsh9QIw6zGh4hsBbAnGZXTxIBGgpmqKcoHdzJfdqIC1RHuvgoV9ogyktZossIvAC3Eto7QI9Afj DJfLcfPQI0zO48D0U9Ge9NpNN/8lG38ZVa5rKumludV0epWm+VghpilY0wwm6m4E1WejyeqfRsfSU6 jyJCN+0lYIo5uPUZjMXWIOsVFgpiZapNIADLiYbYysr0K0TnYttCMbk5xIApBqZGTO32S9fhcQpfSO 1n4Gr11eASSu9+5xsSSYW7FzTEJkWZQa2tykBmm9lVkEdIH4IU7JxhZgOa38SLAsuG4dv6E5xsf4Fw drI3jaegiD87No9WGWLji238b4n/PU X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-4.5 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 04 Jun 2021 11:25:06 -0000 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. 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 (3): 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() arch/arm64/include/asm/elf.h | 13 ++++++++++--- arch/arm64/kernel/process.c | 20 +++++++------------- fs/binfmt_elf.c | 29 ++++++++++++++++++++--------- include/linux/elf.h | 8 +++++--- 4 files changed, 42 insertions(+), 28 deletions(-) base-commit: c4681547bcce777daf576925a966ffa824edd09d -- 2.20.1