From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A60FCC43603 for ; Fri, 6 Dec 2019 22:15:18 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id F17952245C for ; Fri, 6 Dec 2019 22:15:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="SXuPCZw5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F17952245C 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-17479-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 20178 invoked by uid 550); 6 Dec 2019 22:14:27 -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: Received: (qmail 20031 invoked from network); 6 Dec 2019 22:14:26 -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=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=Ttw7LJXCfMpNwPK4N6uZE7yO0z68yt0i/MnXe886btWqsvO3AXYuOgbqsd/Hb9YKQ6 P45XlTJ9t8LsWKBOYYIHRm5KvnY6ekT+BHnwsQaDSCdQorTgA0G2+FbrPi4xveY1Be7e T9A4qqTc0+kDr6L9PBGgW2FMlRQ1DQUxEyzreLYtY21pT0ivI4h2LSfPqKHhHSzVKDv/ 51zv4pshzjSOMyHiZ5Wvsu+FyZ6PjrwYMTyxzOP1Kq09eoP/qRA8O9RKc/z50WYbwNSh iMr4o0FoCW7J5xGWB2zcswDyyAlHQev16LjyjeGBZnIcz7NLYvV25MemTvTVJFHntq8N dqFA== X-Gm-Message-State: APjAAAWg5N+/zLXGC/U9a6gUDtIqGM6wChrR7MSj+KdLbcGGrb8xfHTI BFH5aLqF7aEe+XDZx148TGp4haO/NStKS/9d4gM= 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 Cc: Dave Martin , Kees Cook , Laura Abbott , Marc Zyngier , Nick Desaulniers , Jann Horn , Miguel Ojeda , Masahiro Yamada , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Sami Tolvanen Content-Type: text/plain; charset="UTF-8" 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); -- 2.24.0.393.g34dc348eaf-goog