From patchwork Thu Aug 16 22:17:01 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Popov X-Patchwork-Id: 10568257 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 09FFB13B4 for ; Thu, 16 Aug 2018 22:18:46 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id EBC4E2B8C4 for ; Thu, 16 Aug 2018 22:18:45 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id DE7972B8C8; Thu, 16 Aug 2018 22:18:45 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id ABD082B8C4 for ; Thu, 16 Aug 2018 22:18:44 +0000 (UTC) Received: (qmail 28514 invoked by uid 550); 16 Aug 2018 22:17:57 -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 28372 invoked from network); 16 Aug 2018 22:17:51 -0000 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:in-reply-to :references; bh=TnHmeoXB27+xaH/w7RKi37lqLzmtJxa1KZ8894T2XHg=; b=mplrJi9TJ7wDZV8KArU8U1CF9tuC2JghFeLKVbbnHABrxa25VFalFRQvS8vUNZ110L HOIo+xKCBmS1ovT15fzOmvRqDCWgH7Mrym+NpNm6lg6MdZiYs3B5zqMG+LVajaPTyav0 NhdINBVqwHNbEiwKTja9BrZZDjPSDH9eg9yD3fJ0Papw4NA7XZ17y3spdqzmGknT7cdz hrjhYplJAmsxKdkY5QKAqXo4ytzC5kMPZlDbaT0cCXwvT+LzwzunK4t0vLKevVTcdXox 8Jtaa+/D3lIu4mYXEmB2U4MUCXXUHlkpWTXCdA/2sll7QW1BtYBOWjR6yIgRGX6NdeWe LPGg== X-Gm-Message-State: AOUpUlGDehDwPE0OgOnhFskKXaaAGUw4vL1ch9IZj3nhIY4bx8k7wmxE n83X42X94sR8+YRJvZPeOgYRL6VVeEg= X-Google-Smtp-Source: AA+uWPwNZqQ/DFXHK25drQbaKMnU1GFYw8oyVof4X17/cpXAAnWdxT3ImdDMkXV+OuGZk2eB/BZ8AQ== X-Received: by 2002:a19:df43:: with SMTP id q3-v6mr19721699lfj.53.1534457860313; Thu, 16 Aug 2018 15:17:40 -0700 (PDT) From: Alexander Popov To: kernel-hardening@lists.openwall.com, Kees Cook , PaX Team , Brad Spengler , Ingo Molnar , Andy Lutomirski , Tycho Andersen , Laura Abbott , Mark Rutland , Ard Biesheuvel , Borislav Petkov , Richard Sandiford , Thomas Gleixner , "H . Peter Anvin" , Peter Zijlstra , "Dmitry V . Levin" , Emese Revfy , Jonathan Corbet , Andrey Ryabinin , "Kirill A . Shutemov" , Thomas Garnier , Andrew Morton , Alexei Starovoitov , Josef Bacik , Masami Hiramatsu , Nicholas Piggin , Al Viro , "David S . Miller" , Ding Tianhong , David Woodhouse , Josh Poimboeuf , Steven Rostedt , Dominik Brodowski , Juergen Gross , Linus Torvalds , Greg Kroah-Hartman , Dan Williams , Dave Hansen , Mathias Krause , Vikas Shivappa , Kyle Huey , Dmitry Safonov , Will Deacon , Arnd Bergmann , Florian Weimer , Boris Lukashev , Andrey Konovalov , x86@kernel.org, linux-kernel@vger.kernel.org, alex.popov@linux.com Subject: [PATCH v15 4/7] fs/proc: Show STACKLEAK metrics in the /proc file system Date: Fri, 17 Aug 2018 01:17:01 +0300 Message-Id: <1534457824-7211-5-git-send-email-alex.popov@linux.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1534457824-7211-1-git-send-email-alex.popov@linux.com> References: <1534457824-7211-1-git-send-email-alex.popov@linux.com> X-Virus-Scanned: ClamAV using ClamSMTP Introduce CONFIG_STACKLEAK_METRICS providing STACKLEAK information about tasks via the /proc file system. In particular, /proc//stack_depth shows the maximum kernel stack consumption for the current and previous syscalls. Although this information is not precise, it can be useful for estimating the STACKLEAK performance impact for your workloads. Suggested-by: Ingo Molnar Signed-off-by: Alexander Popov --- fs/proc/base.c | 18 ++++++++++++++++++ include/linux/sched.h | 1 + include/linux/stackleak.h | 3 +++ kernel/stackleak.c | 4 ++++ scripts/gcc-plugins/Kconfig | 12 ++++++++++++ 5 files changed, 38 insertions(+) diff --git a/fs/proc/base.c b/fs/proc/base.c index aaffc0c..66ee5b7 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2893,6 +2893,21 @@ static int proc_pid_patch_state(struct seq_file *m, struct pid_namespace *ns, } #endif /* CONFIG_LIVEPATCH */ +#ifdef CONFIG_STACKLEAK_METRICS +static int proc_stack_depth(struct seq_file *m, struct pid_namespace *ns, + struct pid *pid, struct task_struct *task) +{ + unsigned long prev_depth = THREAD_SIZE - + (task->prev_lowest_stack & (THREAD_SIZE - 1)); + unsigned long depth = THREAD_SIZE - + (task->lowest_stack & (THREAD_SIZE - 1)); + + seq_printf(m, "previous stack depth: %lu\nstack depth: %lu\n", + prev_depth, depth); + return 0; +} +#endif /* CONFIG_STACKLEAK_METRICS */ + /* * Thread groups */ @@ -2994,6 +3009,9 @@ static const struct pid_entry tgid_base_stuff[] = { #ifdef CONFIG_LIVEPATCH ONE("patch_state", S_IRUSR, proc_pid_patch_state), #endif +#ifdef CONFIG_STACKLEAK_METRICS + ONE("stack_depth", S_IRUGO, proc_stack_depth), +#endif }; static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx) diff --git a/include/linux/sched.h b/include/linux/sched.h index bbf2f7a..2540d0e 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1189,6 +1189,7 @@ struct task_struct { #ifdef CONFIG_GCC_PLUGIN_STACKLEAK unsigned long lowest_stack; + unsigned long prev_lowest_stack; #endif /* diff --git a/include/linux/stackleak.h b/include/linux/stackleak.h index 628c2b9..b911b97 100644 --- a/include/linux/stackleak.h +++ b/include/linux/stackleak.h @@ -18,6 +18,9 @@ static inline void stackleak_task_init(struct task_struct *t) { t->lowest_stack = (unsigned long)end_of_stack(t) + sizeof(unsigned long); +# ifdef CONFIG_STACKLEAK_METRICS + t->prev_lowest_stack = t->lowest_stack; +# endif } #else /* !CONFIG_GCC_PLUGIN_STACKLEAK */ static inline void stackleak_task_init(struct task_struct *t) { } diff --git a/kernel/stackleak.c b/kernel/stackleak.c index 628485d..f662395 100644 --- a/kernel/stackleak.c +++ b/kernel/stackleak.c @@ -41,6 +41,10 @@ asmlinkage void stackleak_erase(void) if (kstack_ptr == boundary) kstack_ptr += sizeof(unsigned long); +#ifdef CONFIG_STACKLEAK_METRICS + current->prev_lowest_stack = kstack_ptr; +#endif + /* * Now write the poison value to the kernel stack. Start from * 'kstack_ptr' and move up till the new 'boundary'. We assume that diff --git a/scripts/gcc-plugins/Kconfig b/scripts/gcc-plugins/Kconfig index cd69bff..f15093b 100644 --- a/scripts/gcc-plugins/Kconfig +++ b/scripts/gcc-plugins/Kconfig @@ -170,4 +170,16 @@ config STACKLEAK_TRACK_MIN_SIZE a stack frame size greater than or equal to this parameter. If unsure, leave the default value 100. +config STACKLEAK_METRICS + bool "Show STACKLEAK metrics in the /proc file system" + depends on GCC_PLUGIN_STACKLEAK + depends on PROC_FS + help + If this is set, STACKLEAK metrics for every task are available in + the /proc file system. In particular, /proc//stack_depth + shows the maximum kernel stack consumption for the current and + previous syscalls. Although this information is not precise, it + can be useful for estimating the STACKLEAK performance impact for + your workloads. + endif