From patchwork Fri Nov 6 00:06:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Xu X-Patchwork-Id: 11885481 X-Patchwork-Delegate: bpf@iogearbox.net 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=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 48FF4C388F7 for ; Fri, 6 Nov 2020 00:06:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D705420786 for ; Fri, 6 Nov 2020 00:06:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=dxuuu.xyz header.i=@dxuuu.xyz header.b="kc2XFpTC"; dkim=temperror (0-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="cCOx0iu/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732727AbgKFAGw (ORCPT ); Thu, 5 Nov 2020 19:06:52 -0500 Received: from out5-smtp.messagingengine.com ([66.111.4.29]:59487 "EHLO out5-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729162AbgKFAGt (ORCPT ); Thu, 5 Nov 2020 19:06:49 -0500 Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailout.nyi.internal (Postfix) with ESMTP id 371905C0236; Thu, 5 Nov 2020 19:06:48 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute3.internal (MEProxy); Thu, 05 Nov 2020 19:06:48 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dxuuu.xyz; h= from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; s=fm1; bh=mkQNWZBo7LAmh Gnqr0maVLRmZnUOpV0QQCTASmqfUzw=; b=kc2XFpTCzvdVbSWvKFkR3brub8cob cFB4LY6w8D0QsjQU/qrNwVbTqCvgU2jGinCmZyI75uPCQHrPTGandCV/+zlgBy44 CMOdhjpjdcSqFHsGSGVBhdCbDNoNGp6Df3re3ufMU1tUOoveujq16BtmYJLYYuht 75vdo/ip3BagD3oHwg7qv0onyvJftuPD+lZNExrLMxdzDsc6RRE4jkcQBbRqCGFx 9pNHwrLhjH5vdKW/8X6o07ivHa3kiy/xMh0p6GxfZIS98kyFbVoWWMoSZsTaBQ4Z H0Iimvi8MeRtuqS8woezslb9JLfXJwCkNukf+ukirr7IZC7pVtUeSzRCw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:date:from :in-reply-to:message-id:mime-version:references:subject:to :x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm1; bh=mkQNWZBo7LAmhGnqr0maVLRmZnUOpV0QQCTASmqfUzw=; b=cCOx0iu/ pl2ufcvgyJkeo3c0cnCRagpzc6oEfb07uAAw15qDvUB9JmTzEsyuFdT1PctsFPj9 VR2vjWmuXxFBBhNB8HeoPGBzGDjW+ZY9NBkTQpQVlUBWqGHvDa1eKRhEu3bEoUM4 m7BjHhbIeWJZ3VXrH3Mm+VMhB6D7vsGEV8anC7qsycajqC4CfGngmrza4ZwNaYZP 95i8v7tE3EHGC+ODghtoJYQa4BPV9UOM5vmXW/Y/WHxffwwgowdJJLtDH+GSyEMV +Sk8bd0V9ZPnTDCHVWIpwyFxt9/6frj7Knq4pWvVS/cnPHyzXhi0137NlzoHXaMZ xc20UgA9DnuHbA== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedujedruddtkedgudelucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucgfrhhlucfvnfffucdljedtmdenucfjughrpefhvf fufffkofgjfhgggfestdekredtredttdenucfhrhhomhepffgrnhhivghlucgiuhcuoegu gihusegugihuuhhurdighiiiqeenucggtffrrghtthgvrhhnpefgkeduleekhfetvefhge fgvdegfeejfefguedvuddthffggffhhedtueeuteefieenucfkphepieelrddukedurddu tdehrdeigeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhroh hmpegugihusegugihuuhhurdighiii X-ME-Proxy: Received: from localhost.localdomain (c-69-181-105-64.hsd1.ca.comcast.net [69.181.105.64]) by mail.messagingengine.com (Postfix) with ESMTPA id 3A71C328037B; Thu, 5 Nov 2020 19:06:47 -0500 (EST) From: Daniel Xu To: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, songliubraving@fb.com, andrii.nakryiko@gmail.com Cc: Daniel Xu , kernel-team@fb.com Subject: [PATCH bpf v4 2/2] selftest/bpf: Test bpf_probe_read_user_str() strips trailing bytes after NUL Date: Thu, 5 Nov 2020 16:06:35 -0800 Message-Id: <8b8c8f51aff8fabac4425da9b0054b4c976c944b.1604620776.git.dxu@dxuuu.xyz> X-Mailer: git-send-email 2.28.0 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Previously, bpf_probe_read_user_str() could potentially overcopy the trailing bytes after the NUL due to how do_strncpy_from_user() does the copy in long-sized strides. The issue has been fixed in the previous commit. This commit adds a selftest that ensures we don't regress bpf_probe_read_user_str() again. Signed-off-by: Daniel Xu Acked-by: Song Liu Acked-by: Andrii Nakryiko --- .../bpf/prog_tests/probe_read_user_str.c | 71 +++++++++++++++++++ .../bpf/progs/test_probe_read_user_str.c | 25 +++++++ 2 files changed, 96 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/probe_read_user_str.c create mode 100644 tools/testing/selftests/bpf/progs/test_probe_read_user_str.c diff --git a/tools/testing/selftests/bpf/prog_tests/probe_read_user_str.c b/tools/testing/selftests/bpf/prog_tests/probe_read_user_str.c new file mode 100644 index 000000000000..e419298132b5 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/probe_read_user_str.c @@ -0,0 +1,71 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include "test_probe_read_user_str.skel.h" + +static const char str1[] = "mestring"; +static const char str2[] = "mestringalittlebigger"; +static const char str3[] = "mestringblubblubblubblubblub"; + +static int test_one_str(struct test_probe_read_user_str *skel, const char *str, + size_t len) +{ + int err, duration = 0; + char buf[256]; + + /* Ensure bytes after string are ones */ + memset(buf, 1, sizeof(buf)); + memcpy(buf, str, len); + + /* Give prog our userspace pointer */ + skel->bss->user_ptr = buf; + + /* Trigger tracepoint */ + usleep(1); + + /* Did helper fail? */ + if (CHECK(skel->bss->ret < 0, "prog_ret", "prog returned: %ld\n", + skel->bss->ret)) + return 1; + + /* Check that string was copied correctly */ + err = memcmp(skel->bss->buf, str, len); + if (CHECK(err, "memcmp", "prog copied wrong string")) + return 1; + + /* Now check that no extra trailing bytes were copied */ + memset(buf, 0, sizeof(buf)); + err = memcmp(skel->bss->buf + len, buf, sizeof(buf) - len); + if (CHECK(err, "memcmp", "trailing bytes were not stripped")) + return 1; + + return 0; +} + +void test_probe_read_user_str(void) +{ + struct test_probe_read_user_str *skel; + int err, duration = 0; + + skel = test_probe_read_user_str__open_and_load(); + if (CHECK(!skel, "test_probe_read_user_str__open_and_load", + "skeleton open and load failed\n")) + return; + + /* Give pid to bpf prog so it doesn't read from anyone else */ + skel->bss->pid = getpid(); + + err = test_probe_read_user_str__attach(skel); + if (CHECK(err, "test_probe_read_user_str__attach", + "skeleton attach failed: %d\n", err)) + goto out; + + if (test_one_str(skel, str1, sizeof(str1))) + goto out; + if (test_one_str(skel, str2, sizeof(str2))) + goto out; + if (test_one_str(skel, str3, sizeof(str3))) + goto out; + +out: + test_probe_read_user_str__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/test_probe_read_user_str.c b/tools/testing/selftests/bpf/progs/test_probe_read_user_str.c new file mode 100644 index 000000000000..3ae398b75dcd --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_probe_read_user_str.c @@ -0,0 +1,25 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include + +#include + +pid_t pid = 0; +long ret = 0; +void *user_ptr = 0; +char buf[256] = {}; + +SEC("tracepoint/syscalls/sys_enter_nanosleep") +int on_write(void *ctx) +{ + if (pid != (bpf_get_current_pid_tgid() >> 32)) + return 0; + + ret = bpf_probe_read_user_str(buf, sizeof(buf), user_ptr); + + return 0; +} + +char _license[] SEC("license") = "GPL";