glibc/nss/nss_test_errno.c
Florian Weimer 9bdf92c79d 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 <carlos@redhat.com>
2022-03-11 08:24:19 +01:00

59 lines
1.7 KiB
C

/* 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
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <nss.h>
#include <stdlib.h>
/* 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;
}