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=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 46FF5C433E0 for ; Tue, 9 Jun 2020 04:34:47 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0020120820 for ; Tue, 9 Jun 2020 04:34:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="el/2rVh9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0020120820 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A06768D001F; Tue, 9 Jun 2020 00:34:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9DC058D0011; Tue, 9 Jun 2020 00:34:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8F13E8D001F; Tue, 9 Jun 2020 00:34:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0106.hostedemail.com [216.40.44.106]) by kanga.kvack.org (Postfix) with ESMTP id 765878D0011 for ; Tue, 9 Jun 2020 00:34:46 -0400 (EDT) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 385D42490 for ; Tue, 9 Jun 2020 04:34:46 +0000 (UTC) X-FDA: 76908407772.28.cart77_370269f26dbf Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin28.hostedemail.com (Postfix) with ESMTP id 128ED6D6F for ; Tue, 9 Jun 2020 04:34:46 +0000 (UTC) X-HE-Tag: cart77_370269f26dbf X-Filterd-Recvd-Size: 6941 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf44.hostedemail.com (Postfix) with ESMTP for ; Tue, 9 Jun 2020 04:34:45 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 85EC620888; Tue, 9 Jun 2020 04:34:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591677285; bh=yZhcX8EF8Rq7gqHuzV06Kjp02hHg/grXaejgWOv0nLs=; h=Date:From:To:Subject:In-Reply-To:From; b=el/2rVh9DgnUxY78Aq22WkB2obtlkF7lvq6lb1lrf0qXpLBYhEmGn4bZvll5DLPVT By5MXP8OZFoHxK5jpAnLy4dYnXz3a12Idt2j9riKIkbQcIY9wbTfDJXQL+Uqs/fqrO x6b3nkIZSertIA6ur0GEQ8AXd+TTuV95ZFZ6lAGE= Date: Mon, 08 Jun 2020 21:34:44 -0700 From: Andrew Morton To: akpm@linux-foundation.org, ast@kernel.org, daniel@iogearbox.net, hch@lst.de, hpa@zytor.com, linux-mm@kvack.org, mhiramat@kernel.org, mingo@elte.hu, mm-commits@vger.kernel.org, svens@linux.ibm.com, tglx@linutronix.de, torvalds@linux-foundation.org Subject: [patch 86/93] tracing/kprobes: handle mixed kernel/userspace probes better Message-ID: <20200609043444.8qanU5wfk%akpm@linux-foundation.org> In-Reply-To: <20200608212922.5b7fa74ca3f4e2444441b7f9@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Queue-Id: 128ED6D6F X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Christoph Hellwig Subject: tracing/kprobes: handle mixed kernel/userspace probes better 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. [svens@linux.ibm.com:use strncpy_from_kernel_nofault() in fetch_store_string()] Link: http://lkml.kernel.org/r/20200606181903.49384-1-svens@linux.ibm.com Link: http://lkml.kernel.org/r/20200521152301.2587579-15-hch@lst.de Signed-off-by: Christoph Hellwig Signed-off-by: Sven Schnelle Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Masami Hiramatsu Cc: Thomas Gleixner Signed-off-by: Andrew Morton --- kernel/trace/trace_kprobe.c | 72 ++++++++++++++++++++-------------- 1 file changed, 43 insertions(+), 29 deletions(-) --- a/kernel/trace/trace_kprobe.c~tracing-kprobes-handle-mixed-kernel-userspace-probes-better +++ a/kernel/trace/trace_kprobe.c @@ -1202,35 +1202,41 @@ static const struct file_operations kpro /* 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) { 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, v __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); @@ -1252,23 +1254,31 @@ fetch_store_string(unsigned long addr, v } /* - * 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_kernel_nofault(__dest, (void *)addr, maxlen); if (ret >= 0) *(u32 *)dest = make_data_loc(ret, __dest - base); @@ -1276,12 +1286,6 @@ fetch_store_string_user(unsigned long ad } 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) { const void __user *uaddr = (__force const void __user *)src; @@ -1289,6 +1293,16 @@ probe_mem_read_user(void *dest, void *sr 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, _