From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id E0898385841D for ; Thu, 10 Mar 2022 14:35:47 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org E0898385841D Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-218-FxYZcEcsN36WwOeVhPy6PA-1; Thu, 10 Mar 2022 09:35:45 -0500 X-MC-Unique: FxYZcEcsN36WwOeVhPy6PA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A7DBF801AFE for ; Thu, 10 Mar 2022 14:35:44 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.88]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E903767E7A for ; Thu, 10 Mar 2022 14:35:43 +0000 (UTC) From: Florian Weimer To: libc-alpha@sourceware.org Subject: [PATCH v2 2/2] nss: Protect against errno changes in function lookup (bug 28953) In-Reply-To: <7ce5ab8833fc46897b05be07f243e10893571c2d.1646922805.git.fweimer@redhat.com> References: <7ce5ab8833fc46897b05be07f243e10893571c2d.1646922805.git.fweimer@redhat.com> X-From-Line: ccc2d096177bf9db5f86499777e31c545cfa39a1 Mon Sep 17 00:00:00 2001 Message-Id: Date: Thu, 10 Mar 2022 15:35:42 +0100 User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-11.9 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H5, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 Mar 2022 14:35:49 -0000 dlopen may clobber errno. The nss_test_errno module uses an ELF constructor to achieve that, but there could be internal errors during dlopen that cause this, too. Therefore, the NSS framework has to guard against such errno clobbers. __nss_module_get_function is currently the only function that calls __nss_module_load, so it is sufficient to save and restore errno around this call. --- v2: Fix copyright headers. Use $(libnss_files.so-version). Add test module dependency in the right place. nss/Makefile | 15 ++++++++-- nss/nss_module.c | 5 ++++ nss/nss_test_errno.c | 58 ++++++++++++++++++++++++++++++++++++++ nss/tst-nss-test_errno.c | 61 ++++++++++++++++++++++++++++++++++++++++ 4 files changed, 136 insertions(+), 3 deletions(-) create mode 100644 nss/nss_test_errno.c create mode 100644 nss/tst-nss-test_errno.c diff --git a/nss/Makefile b/nss/Makefile index 74e2c2426c..de439d4911 100644 --- a/nss/Makefile +++ b/nss/Makefile @@ -60,7 +60,8 @@ tests = test-netdb test-digits-dots tst-nss-getpwent bug17079 \ tst-nss-test1 \ tst-nss-test2 \ tst-nss-test4 \ - tst-nss-test5 + tst-nss-test5 \ + tst-nss-test_errno xtests = bug-erange tests-container = \ @@ -132,7 +133,7 @@ libnss_compat-inhibit-o = $(filter-out .os,$(object-suffixes)) ifeq ($(build-static-nss),yes) tests-static += tst-nss-static endif -extra-test-objs += nss_test1.os nss_test2.os +extra-test-objs += nss_test1.os nss_test2.os nss_test_errno.os include ../Rules @@ -166,19 +167,26 @@ rtld-tests-LDFLAGS += -Wl,--dynamic-list=nss_test.ver libof-nss_test1 = extramodules libof-nss_test2 = extramodules +libof-nss_test_errno = extramodules $(objpfx)/libnss_test1.so: $(objpfx)nss_test1.os $(link-libc-deps) $(build-module) $(objpfx)/libnss_test2.so: $(objpfx)nss_test2.os $(link-libc-deps) $(build-module) +$(objpfx)/libnss_test_errno.so: $(objpfx)nss_test_errno.os $(link-libc-deps) + $(build-module) $(objpfx)nss_test2.os : nss_test1.c # Use the nss_files suffix for these objects as well. $(objpfx)/libnss_test1.so$(libnss_files.so-version): $(objpfx)/libnss_test1.so $(make-link) $(objpfx)/libnss_test2.so$(libnss_files.so-version): $(objpfx)/libnss_test2.so $(make-link) +$(objpfx)/libnss_test_errno.so$(libnss_files.so-version): \ + $(objpfx)/libnss_test_errno.so + $(make-link) $(patsubst %,$(objpfx)%.out,$(tests) $(tests-container)) : \ $(objpfx)/libnss_test1.so$(libnss_files.so-version) \ - $(objpfx)/libnss_test2.so$(libnss_files.so-version) + $(objpfx)/libnss_test2.so$(libnss_files.so-version) \ + $(objpfx)/libnss_test_errno.so$(libnss_files.so-version) ifeq (yes,$(have-thread-library)) $(objpfx)tst-cancel-getpwuid_r: $(shared-thread-library) @@ -194,3 +202,4 @@ LDFLAGS-tst-nss-test2 = -Wl,--disable-new-dtags LDFLAGS-tst-nss-test3 = -Wl,--disable-new-dtags LDFLAGS-tst-nss-test4 = -Wl,--disable-new-dtags LDFLAGS-tst-nss-test5 = -Wl,--disable-new-dtags +LDFLAGS-tst-nss-test_errno = -Wl,--disable-new-dtags diff --git a/nss/nss_module.c b/nss/nss_module.c index f9a1263e5a..4839448e35 100644 --- a/nss/nss_module.c +++ b/nss/nss_module.c @@ -330,9 +330,14 @@ name_search (const void *left, const void *right) void * __nss_module_get_function (struct nss_module *module, const char *name) { + /* A successful dlopen might clobber errno. */ + int saved_errno = errno; + if (!__nss_module_load (module)) return NULL; + __set_errno (saved_errno); + function_name *name_entry = bsearch (name, nss_function_name_array, array_length (nss_function_name_array), sizeof (function_name), name_search); diff --git a/nss/nss_test_errno.c b/nss/nss_test_errno.c new file mode 100644 index 0000000000..680f8a07b9 --- /dev/null +++ b/nss/nss_test_errno.c @@ -0,0 +1,58 @@ +/* NSS service provider with errno clobber. + Copyright (C) 2022 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#include +#include +#include + +/* Catch misnamed and functions. */ +#pragma GCC diagnostic error "-Wmissing-prototypes" +NSS_DECLARE_MODULE_FUNCTIONS (test_errno) + +static void __attribute__ ((constructor)) +init (void) +{ + /* An arbitrary error code which is otherwise not used. */ + errno = ELIBBAD; +} + +/* Lookup functions for pwd follow that do not return any data. */ + +/* Catch misnamed function definitions. */ + +enum nss_status +_nss_test_errno_setpwent (int stayopen) +{ + setenv ("_nss_test_errno_setpwent", "yes", 1); + return NSS_STATUS_SUCCESS; +} + +enum nss_status +_nss_test_errno_getpwent_r (struct passwd *result, + char *buffer, size_t size, int *errnop) +{ + setenv ("_nss_test_errno_getpwent_r", "yes", 1); + return NSS_STATUS_NOTFOUND; +} + +enum nss_status +_nss_test_errno_endpwent (void) +{ + setenv ("_nss_test_errno_endpwent", "yes", 1); + return NSS_STATUS_SUCCESS; +} diff --git a/nss/tst-nss-test_errno.c b/nss/tst-nss-test_errno.c new file mode 100644 index 0000000000..d2c42dd363 --- /dev/null +++ b/nss/tst-nss-test_errno.c @@ -0,0 +1,61 @@ +/* getpwent failure when dlopen clobbers errno (bug 28953). + Copyright (C) 2022 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#include +#include +#include +#include +#include +#include +#include + +static int +do_test (void) +{ + __nss_configure_lookup ("passwd", "files test_errno"); + + errno = 0; + setpwent (); + TEST_COMPARE (errno, 0); + + bool root_seen = false; + while (true) + { + errno = 0; + struct passwd *e = getpwent (); + if (e == NULL) + break; + if (strcmp (e->pw_name, "root")) + root_seen = true; + } + + TEST_COMPARE (errno, 0); + TEST_VERIFY (root_seen); + + errno = 0; + endpwent (); + TEST_COMPARE (errno, 0); + + TEST_COMPARE_STRING (getenv ("_nss_test_errno_setpwent"), "yes"); + TEST_COMPARE_STRING (getenv ("_nss_test_errno_getpwent_r"), "yes"); + TEST_COMPARE_STRING (getenv ("_nss_test_errno_endpwent"), "yes"); + + return 0; +} + +#include -- 2.35.1