From 54b12733959238204d7b0e46e69fc7f7d8890b20 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Fri, 11 Mar 2022 08:23:56 +0100 Subject: nss: Protect against errno changes in function lookup (bug 28953) 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. Reviewed-by: Carlos O'Donell (cherry picked from commit 9bdf92c79d63b42f931101bb6df87129c408b0c4) --- NEWS | 1 + nss/Makefile | 14 ++++++++--- nss/nss_module.c | 12 +++++++++- nss/nss_test_errno.c | 58 +++++++++++++++++++++++++++++++++++++++++++++ nss/tst-nss-test_errno.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 142 insertions(+), 4 deletions(-) create mode 100644 nss/nss_test_errno.c create mode 100644 nss/tst-nss-test_errno.c diff --git a/NEWS b/NEWS index 81f5decd2b..aa442a5e4b 100644 --- a/NEWS +++ b/NEWS @@ -67,6 +67,7 @@ The following bugs are resolved with this release: without /sys and /proc [28896] strncmp-avx2-rtm and wcsncmp-avx2-rtm fallback on non-rtm variants when avoiding overflow + [28953] nss: Protect against errno changes in function lookup Version 2.34 diff --git a/nss/Makefile b/nss/Makefile index e223243d9d..716bc8f6ef 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) diff --git a/nss/nss_module.c b/nss/nss_module.c index b28cb94a6a..3a4a464256 100644 --- a/nss/nss_module.c +++ b/nss/nss_module.c @@ -330,8 +330,18 @@ 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; + { + /* Reporting module load failure is currently inaccurate. See + bug 22041. Not changing errno is the conservative choice. */ + __set_errno (saved_errno); + return NULL; + } + + __set_errno (saved_errno); function_name *name_entry = bsearch (name, nss_function_name_array, array_length (nss_function_name_array), 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 -- cgit 1.4.1