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=-9.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 8CEB6C433DF for ; Thu, 21 May 2020 15:25:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 67E5C20826 for ; Thu, 21 May 2020 15:25:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="tLPDt4CX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730197AbgEUPXv (ORCPT ); Thu, 21 May 2020 11:23:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35200 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730169AbgEUPXr (ORCPT ); Thu, 21 May 2020 11:23:47 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D463BC05BD43; Thu, 21 May 2020 08:23:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description; bh=fxWOG5hif9vKKfwkrFVmM3NLzLAalQTXvsWxwZiBbb8=; b=tLPDt4CXYSglY3h76YESUhYKt7 J7svJNN2VWxKo5fiLN55He0+OYxMwHihpzccA/6pqOIk6QQRZb9GoogD1Bpu4Is9VaqR8zEDC0cBL suVR7wMoiJw/+SyTZTOTr6ocZU+uJOmR8sEZQuFFRTSLjGgWvP9Z52ytdUnOMMTLG2Z9pjZOUVsoR xSp9ZeKjCbRkpyUr2fGcMiaKZxyNKU3jxUVNoSwxusAdbOoCIXEhN1IBBfDnRDEy2bGW2bIHML3AI UH0MnonfWcMF0F7WZcUNh5+bsZPhmwYzF/JZ6Ex+byXTWsNsoM+5KEGXlS8ddrLAQ2PnBd+N9Ysh+ kEKX+18g==; Received: from [2001:4bb8:18c:5da7:c70:4a89:bc61:2] (helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jbn2v-0004WX-EX; Thu, 21 May 2020 15:23:46 +0000 From: Christoph Hellwig To: x86@kernel.org, Alexei Starovoitov , Daniel Borkmann , Masami Hiramatsu , Linus Torvalds , Andrew Morton Cc: linux-parisc@vger.kernel.org, linux-um@lists.infradead.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 14/23] tracing/kprobes: handle mixed kernel/userspace probes better Date: Thu, 21 May 2020 17:22:52 +0200 Message-Id: <20200521152301.2587579-15-hch@lst.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200521152301.2587579-1-hch@lst.de> References: <20200521152301.2587579-1-hch@lst.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Instead of using the dangerous probe_kernel_read and strncpy_from_unsafe helpers, rework probes to try a user probe based on the address if the architecture has a common address space for kernel and userspace. Signed-off-by: Christoph Hellwig --- kernel/trace/trace_kprobe.c | 72 ++++++++++++++++++++++--------------- 1 file changed, 43 insertions(+), 29 deletions(-) diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 4325f9e7fadaa..4aeaef53ba970 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -1200,6 +1200,15 @@ static const struct file_operations kprobe_profile_ops = { /* Kprobe specific fetch functions */ +/* Return the length of string -- including null terminal byte */ +static nokprobe_inline int +fetch_store_strlen_user(unsigned long addr) +{ + const void __user *uaddr = (__force const void __user *)addr; + + return strnlen_user_nofault(uaddr, MAX_STRING_SIZE); +} + /* Return the length of string -- including null terminal byte */ static nokprobe_inline int fetch_store_strlen(unsigned long addr) @@ -1207,30 +1216,27 @@ fetch_store_strlen(unsigned long addr) int ret, len = 0; u8 c; +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE + if (addr < TASK_SIZE) + return fetch_store_strlen_user(addr); +#endif + do { - ret = probe_kernel_read(&c, (u8 *)addr + len, 1); + ret = probe_kernel_read_strict(&c, (u8 *)addr + len, 1); len++; } while (c && ret == 0 && len < MAX_STRING_SIZE); return (ret < 0) ? ret : len; } -/* Return the length of string -- including null terminal byte */ -static nokprobe_inline int -fetch_store_strlen_user(unsigned long addr) -{ - const void __user *uaddr = (__force const void __user *)addr; - - return strnlen_user_nofault(uaddr, MAX_STRING_SIZE); -} - /* - * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max - * length and relative data location. + * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf + * with max length and relative data location. */ static nokprobe_inline int -fetch_store_string(unsigned long addr, void *dest, void *base) +fetch_store_string_user(unsigned long addr, void *dest, void *base) { + const void __user *uaddr = (__force const void __user *)addr; int maxlen = get_loc_len(*(u32 *)dest); void *__dest; long ret; @@ -1240,11 +1246,7 @@ fetch_store_string(unsigned long addr, void *dest, void *base) __dest = get_loc_data(dest, base); - /* - * Try to get string again, since the string can be changed while - * probing. - */ - ret = strncpy_from_unsafe(__dest, (void *)addr, maxlen); + ret = strncpy_from_user_nofault(__dest, uaddr, maxlen); if (ret >= 0) *(u32 *)dest = make_data_loc(ret, __dest - base); @@ -1252,35 +1254,37 @@ fetch_store_string(unsigned long addr, void *dest, void *base) } /* - * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf - * with max length and relative data location. + * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max + * length and relative data location. */ static nokprobe_inline int -fetch_store_string_user(unsigned long addr, void *dest, void *base) +fetch_store_string(unsigned long addr, void *dest, void *base) { - const void __user *uaddr = (__force const void __user *)addr; int maxlen = get_loc_len(*(u32 *)dest); void *__dest; long ret; +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE + if ((unsigned long)addr < TASK_SIZE) + return fetch_store_string_user(addr, dest, base); +#endif + if (unlikely(!maxlen)) return -ENOMEM; __dest = get_loc_data(dest, base); - ret = strncpy_from_user_nofault(__dest, uaddr, maxlen); + /* + * Try to get string again, since the string can be changed while + * probing. + */ + ret = strncpy_from_user_nofault(__dest, (void *)addr, maxlen); if (ret >= 0) *(u32 *)dest = make_data_loc(ret, __dest - base); return ret; } -static nokprobe_inline int -probe_mem_read(void *dest, void *src, size_t size) -{ - return probe_kernel_read(dest, src, size); -} - static nokprobe_inline int probe_mem_read_user(void *dest, void *src, size_t size) { @@ -1289,6 +1293,16 @@ probe_mem_read_user(void *dest, void *src, size_t size) return probe_user_read(dest, uaddr, size); } +static nokprobe_inline int +probe_mem_read(void *dest, void *src, size_t size) +{ +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE + if ((unsigned long)src < TASK_SIZE) + return probe_mem_read_user(dest, src, size); +#endif + return probe_kernel_read_strict(dest, src, size); +} + /* Note that we don't verify it, since the code does not come from user space */ static int process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest, -- 2.26.2