From patchwork Mon Apr 27 16:00:10 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 11512937 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 3BC311392 for ; Mon, 27 Apr 2020 16:01:52 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 98FE4205C9 for ; Mon, 27 Apr 2020 16:01:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="fqLi0Sky" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 98FE4205C9 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-18640-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 12234 invoked by uid 550); 27 Apr 2020 16:00:54 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 12177 invoked from network); 27 Apr 2020 16:00:53 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=jTb4YPIUPKL1E1OLE2ifNkQg2x2HSYmo0hj4Ci3DZ3A=; b=fqLi0SkyPjbXxPX/hPsXZeMNhq35aYqBNJAvT/Xx+BzPh7YlBx6i8WTACzT4FBHIRv yB3PamKTCHUBg04d9KVAhujS595QnxeeGH1EBSaBLJkOM7C2p6uhVroooOZkVWSFANBo EQq7r79O7lYvn3jVBEw+TI04/17VIVUaDIXO9ddhSuge+F4kykHowiB4XA1PixFt7f06 knShlLB1Y6N5OLuGmCs4M7eKqc6BblFu2RW9cdCpUqsLmxzOIrCdokmS7rXLST3WR3EJ 4YBYToSahIZ4xPJWmk/lOEd0e03hxC16yaJ1xBfFhei9FtsLMetBOg+CemUkcnsn0gik hibA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=jTb4YPIUPKL1E1OLE2ifNkQg2x2HSYmo0hj4Ci3DZ3A=; b=mzjOOI4qNZ8KDFQLW5EJ3Jt0L9Gc+OxY916GiX9Ki+EyPraSg8+snbC5TgtTHkQpJM bnhguJmb15DIsB0sfYsYk/S29Jitw/9ltySu/FzKbYhAO7OvNFK18NfbouUayKIhTsHB VYTbUwwgGaeLwJFvOSRzBe2Pu3swvpQrg8Deq10W1vGY5RR7DiTeJl8v8EaHEskfI1K5 E+zsszobZtnSZU0b4uhB3K2r77zHDjH3ENCkMXC8WWe+o3qra05tAGOkscF7/bkI0Wb1 05pf9fExPg5SNgUr6qgrKgcHIwT8MXow+wobfvyQVllPTss469k5YMN6ajxl86OgQc5N gRbA== X-Gm-Message-State: AGi0PuZQY/awW5Jhw6e/O+unuMJ0gjuYrNXW7u4h0C1+/8VQM+QIk55/ IDdQS4pIXEjckzAtyrWG98hPhKoKdzRxC8XZw5U= X-Google-Smtp-Source: APiQypLDtauRhcKiTQyzgC2LQ3XamOTxT1OCw5Clsp9y71dsXWMyuVGmw4gnWIV3Yp64XvmFFiqiRAvcGkJl+hJ0vkc= X-Received: by 2002:a05:6214:1513:: with SMTP id e19mr22507959qvy.75.1588003237430; Mon, 27 Apr 2020 09:00:37 -0700 (PDT) Date: Mon, 27 Apr 2020 09:00:10 -0700 In-Reply-To: <20200427160018.243569-1-samitolvanen@google.com> Message-Id: <20200427160018.243569-5-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20200427160018.243569-1-samitolvanen@google.com> X-Mailer: git-send-email 2.26.2.303.gf8c07b1a785-goog Subject: [PATCH v13 04/12] scs: disable when function graph tracing is enabled From: Sami Tolvanen To: Will Deacon , Catalin Marinas , James Morse , Steven Rostedt , Ard Biesheuvel , Mark Rutland , Masahiro Yamada , Michal Marek , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot Cc: Dave Martin , Kees Cook , Laura Abbott , Marc Zyngier , Masami Hiramatsu , Nick Desaulniers , Jann Horn , Miguel Ojeda , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Sami Tolvanen The graph tracer hooks returns by modifying frame records on the (regular) stack, but with SCS the return address is taken from the shadow stack, and the value in the frame record has no effect. As we don't currently have a mechanism to determine the corresponding slot on the shadow stack (and to pass this through the ftrace infrastructure), for now let's disable SCS when the graph tracer is enabled. With SCS the return address is taken from the shadow stack and the value in the frame record has no effect. The mcount based graph tracer hooks returns by modifying frame records on the (regular) stack, and thus is not compatible. The patchable-function-entry graph tracer used for DYNAMIC_FTRACE_WITH_REGS modifies the LR before it is saved to the shadow stack, and is compatible. Modifying the mcount based graph tracer to work with SCS would require a mechanism to determine the corresponding slot on the shadow stack (and to pass this through the ftrace infrastructure), and we expect that everyone will eventually move to the patchable-function-entry based graph tracer anyway, so for now let's disable SCS when the mcount-based graph tracer is enabled. SCS and patchable-function-entry are both supported from LLVM 10.x. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Reviewed-by: Mark Rutland --- arch/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/Kconfig b/arch/Kconfig index 334a3d9b19df..45dfca9a98d3 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -543,6 +543,7 @@ config ARCH_SUPPORTS_SHADOW_CALL_STACK config SHADOW_CALL_STACK bool "Clang Shadow Call Stack" depends on CC_IS_CLANG && ARCH_SUPPORTS_SHADOW_CALL_STACK + depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER help This option enables Clang's Shadow Call Stack, which uses a shadow stack to protect function return addresses from being