From patchwork Fri Dec 6 22:13:43 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 11277089 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 07AD714BD for ; Fri, 6 Dec 2019 22:16:02 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D4768206DB for ; Fri, 6 Dec 2019 22:16:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="cM9z4XA2"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=google.com header.i=@google.com header.b="SXuPCZw5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D4768206DB Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:To:From:Subject:References:Mime-Version :Message-Id:In-Reply-To:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=QWlq8ch+tXw65p8mtNCHwvdUQthqPTaHYWHGIrWgy6c=; b=cM9z4XA20Pyqti PnUih6ACcYeXRDFAGXzdQJLioBUqzXmhsL/611p4oAk2Sxg/UnocZ7B+T3EvZ3JthpF1L7AY5vp4p cjHuF/wOKRXqjbYm0GT1zX5lgt2gM7F2Z+oQks7BSEPOYoc6sXNDo1w2J82M2+2OHVHJanRApRTN+ Ko7eA59PUkSkg/2q5mCqAZkH8r6hQL4gUrMo0u5ZDDFV8FCdT6uPhWIScwvyDeZmUU/PPUqcPiCXM 90G3lOCF8PqJEQLRBkjdVBYkxKNnTXC7IMmwp/y0G4b7LZfdeFQdUa1hnPvtbtlIYu6w9dY+2WQT3 3V+2p4QuFcMejk8kq7Cw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1idLtG-0000zL-WA; Fri, 06 Dec 2019 22:15:59 +0000 Received: from mail-pf1-x449.google.com ([2607:f8b0:4864:20::449]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1idLrb-0006eW-LG for linux-arm-kernel@lists.infradead.org; Fri, 06 Dec 2019 22:14:17 +0000 Received: by mail-pf1-x449.google.com with SMTP id h22so4782149pfo.18 for ; Fri, 06 Dec 2019 14:14:14 -0800 (PST) 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=dSkqIg9MhTEqSRuUPD+wLwf3dmJwcSH5rhdG+lQGY0Y=; b=SXuPCZw5St6pvwTst8kmf5KElVFLKMFMp+CAkmkUaQLus5cyU/8kqr6V5JxAIwmDV8 RWdDAn+WZ18vV4T9eqQoonAjHW3Rzl/rq+nVdoOiKpP2KO897WS7qgb0uHjTrgJkEo1F 0w2fuPU7iE//Mhmc1AStldjXFL0gQujdjqFyhIQqo0PX3BYn+fe6w0aILNtXks9GiWbX y15Zqo4dF7akKdP8o3QHjsZgpRBi+Vh9QT2pwFLxPBRKjS+x9TmrUCopcszBpJQvv4wL EQLbAdHZz6TZ6uqyOto/Ft9UcaQoXc6w3u8Hni2mOOXu4O7zVJWi0IlEALO+ifSUBL0a F4QA== 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=dSkqIg9MhTEqSRuUPD+wLwf3dmJwcSH5rhdG+lQGY0Y=; b=BhETv0eChnbxZKkkG1sm9bztHT0qWC0CJD8g9ql5aiD5N24k5l70d9d7dryV1gF9Bg Xon3aSaOXhbi3iQxXTlPzbzXOlpObqdm0KCUWD2OAjis9GiLXijfxSqSY2YnQavMalBZ xwSCG9y2gzLkiV51IUIA9dCP3UQSP7OGJegpSSapatuTgCsoF5rTBxsPteRhSN8ol3F7 q4hBpIOOgTxYXn48vNg1le8yTFTxFpfX7K5LXO5UVD63hrcM2mtCZeWLJQ6yX/lspgQY /nWkpL7iXO2y4VnymLsy7xET1tUxIrgBnZkHP5WFpHVmL3IRQgHXHHV2Pe6xHRsGQ8om yWxA== X-Gm-Message-State: APjAAAWMQqRPqFHnmMGKyvMyp5O5BUPRquatQJuyFzkK3zh68oqlZ9HA ubFDHL789QU9EX9eoPZaZwPao5uQ/20SuHNCeUk= X-Google-Smtp-Source: APXvYqwr9gV3C2U9Vw8KNYzBqn9JcBiVcajDSJ2lm7uPyamXFOot36lh81Wh0+CfZKTc60xlWZW4gj6RW7XavjkgTmE= X-Received: by 2002:a63:4b52:: with SMTP id k18mr5960727pgl.371.1575670454000; Fri, 06 Dec 2019 14:14:14 -0800 (PST) Date: Fri, 6 Dec 2019 14:13:43 -0800 In-Reply-To: <20191206221351.38241-1-samitolvanen@google.com> Message-Id: <20191206221351.38241-8-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191206221351.38241-1-samitolvanen@google.com> X-Mailer: git-send-email 2.24.0.393.g34dc348eaf-goog Subject: [PATCH v6 07/15] scs: add support for stack usage debugging From: Sami Tolvanen To: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Mark Rutland X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191206_141415_709446_BF409397 X-CRM114-Status: UNSURE ( 9.78 ) X-CRM114-Notice: Please train this message. X-Spam-Score: -7.7 (-------) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (-7.7 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [2607:f8b0:4864:20:0:0:0:449 listed in] [list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -7.5 USER_IN_DEF_DKIM_WL From: address is in the default DKIM white-list -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.0 DKIMWL_WL_MED DKIMwl.org - Medium sender X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kees Cook , Jann Horn , Masahiro Yamada , Marc Zyngier , kernel-hardening@lists.openwall.com, Nick Desaulniers , linux-kernel@vger.kernel.org, Miguel Ojeda , clang-built-linux@googlegroups.com, Sami Tolvanen , Laura Abbott , Dave Martin , linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Implements CONFIG_DEBUG_STACK_USAGE for shadow stacks. When enabled, also prints out the highest shadow stack usage per process. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook --- kernel/scs.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/kernel/scs.c b/kernel/scs.c index 5245e992c692..ad74d13f2c0f 100644 --- a/kernel/scs.c +++ b/kernel/scs.c @@ -184,6 +184,44 @@ int scs_prepare(struct task_struct *tsk, int node) return 0; } +#ifdef CONFIG_DEBUG_STACK_USAGE +static inline unsigned long scs_used(struct task_struct *tsk) +{ + unsigned long *p = __scs_base(tsk); + unsigned long *end = scs_magic(p); + unsigned long s = (unsigned long)p; + + while (p < end && READ_ONCE_NOCHECK(*p)) + p++; + + return (unsigned long)p - s; +} + +static void scs_check_usage(struct task_struct *tsk) +{ + static DEFINE_SPINLOCK(lock); + static unsigned long highest; + unsigned long used = scs_used(tsk); + + if (used <= highest) + return; + + spin_lock(&lock); + + if (used > highest) { + pr_info("%s (%d): highest shadow stack usage: %lu bytes\n", + tsk->comm, task_pid_nr(tsk), used); + highest = used; + } + + spin_unlock(&lock); +} +#else +static inline void scs_check_usage(struct task_struct *tsk) +{ +} +#endif + bool scs_corrupted(struct task_struct *tsk) { unsigned long *magic = scs_magic(__scs_base(tsk)); @@ -200,6 +238,7 @@ void scs_release(struct task_struct *tsk) return; WARN_ON(scs_corrupted(tsk)); + scs_check_usage(tsk); scs_account(tsk, -1); task_set_scs(tsk, NULL);