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,USER_AGENT_GIT autolearn=ham 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 22B87C433E0 for ; Thu, 21 May 2020 15:45:22 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D50B0207D8 for ; Thu, 21 May 2020 15:45:21 +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" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D50B0207D8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 839E48000F; Thu, 21 May 2020 11:45:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7E90880008; Thu, 21 May 2020 11:45:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6FE658000F; Thu, 21 May 2020 11:45:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0166.hostedemail.com [216.40.44.166]) by kanga.kvack.org (Postfix) with ESMTP id 5A71080008 for ; Thu, 21 May 2020 11:45:21 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 052A24404 for ; Thu, 21 May 2020 15:45:21 +0000 (UTC) X-FDA: 76841150442.01.wrist39_85f8f114b4934 X-HE-Tag: wrist39_85f8f114b4934 X-Filterd-Recvd-Size: 6943 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf22.hostedemail.com (Postfix) with ESMTP for ; Thu, 21 May 2020 15:45:20 +0000 (UTC) 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 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Content-Transfer-Encoding: quoted-printable 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: 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 =3D { =20 /* Kprobe specific fetch functions */ =20 +/* Return the length of string -- including null terminal byte */ +static nokprobe_inline int +fetch_store_strlen_user(unsigned long addr) +{ + const void __user *uaddr =3D (__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 =3D 0; u8 c; =20 +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE + if (addr < TASK_SIZE) + return fetch_store_strlen_user(addr); +#endif + do { - ret =3D probe_kernel_read(&c, (u8 *)addr + len, 1); + ret =3D probe_kernel_read_strict(&c, (u8 *)addr + len, 1); len++; } while (c && ret =3D=3D 0 && len < MAX_STRING_SIZE); =20 return (ret < 0) ? ret : len; } =20 -/* Return the length of string -- including null terminal byte */ -static nokprobe_inline int -fetch_store_strlen_user(unsigned long addr) -{ - const void __user *uaddr =3D (__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 =3D (__force const void __user *)addr; int maxlen =3D get_loc_len(*(u32 *)dest); void *__dest; long ret; @@ -1240,11 +1246,7 @@ fetch_store_string(unsigned long addr, void *dest,= void *base) =20 __dest =3D get_loc_data(dest, base); =20 - /* - * Try to get string again, since the string can be changed while - * probing. - */ - ret =3D strncpy_from_unsafe(__dest, (void *)addr, maxlen); + ret =3D strncpy_from_user_nofault(__dest, uaddr, maxlen); if (ret >=3D 0) *(u32 *)dest =3D make_data_loc(ret, __dest - base); =20 @@ -1252,35 +1254,37 @@ fetch_store_string(unsigned long addr, void *dest= , void *base) } =20 /* - * 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 =3D (__force const void __user *)addr; int maxlen =3D get_loc_len(*(u32 *)dest); void *__dest; long ret; =20 +#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; =20 __dest =3D get_loc_data(dest, base); =20 - ret =3D strncpy_from_user_nofault(__dest, uaddr, maxlen); + /* + * Try to get string again, since the string can be changed while + * probing. + */ + ret =3D strncpy_from_user_nofault(__dest, (void *)addr, maxlen); if (ret >=3D 0) *(u32 *)dest =3D make_data_loc(ret, __dest - base); =20 return ret; } =20 -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); } =20 +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, --=20 2.26.2