forked from mirrors/nixpkgs
1fbbeff0c1
Fixes CVE-2014-8121, CVE-2015-1781 and two unnumbered problems (apparently). All these commits should be contained in the 2.22 release, but we don't want that yet due to unresolved locale incompatibilites.
231 lines
6.9 KiB
Diff
231 lines
6.9 KiB
Diff
From 03d2730b44cc2236318fd978afa2651753666c55 Mon Sep 17 00:00:00 2001
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From: Florian Weimer <fweimer@redhat.com>
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Date: Wed, 29 Apr 2015 14:41:25 +0200
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Subject: [PATCH] CVE-2014-8121: Do not close NSS files database during
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iteration [BZ #18007]
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MIME-Version: 1.0
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Content-Type: text/plain; charset=utf8
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Content-Transfer-Encoding: 8bit
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Robin Hack discovered Samba would enter an infinite loop processing
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certain quota-related requests. We eventually tracked this down to a
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glibc issue.
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Running a (simplified) test case under strace shows that /etc/passwd
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is continuously opened and closed:
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â¦
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open("/etc/passwd", O_RDONLY|O_CLOEXEC) = 3
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lseek(3, 0, SEEK_CUR) = 0
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read(3, "root:x:0:0:root:/root:/bin/bash\n"..., 4096) = 2717
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lseek(3, 2717, SEEK_SET) = 2717
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close(3) = 0
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open("/etc/passwd", O_RDONLY|O_CLOEXEC) = 3
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lseek(3, 0, SEEK_CUR) = 0
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lseek(3, 0, SEEK_SET) = 0
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read(3, "root:x:0:0:root:/root:/bin/bash\n"..., 4096) = 2717
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lseek(3, 2717, SEEK_SET) = 2717
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close(3) = 0
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open("/etc/passwd", O_RDONLY|O_CLOEXEC) = 3
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lseek(3, 0, SEEK_CUR) = 0
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â¦
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The lookup function implementation in
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nss/nss_files/files-XXX.c:DB_LOOKUP has code to prevent that. It is
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supposed skip closing the input file if it was already open.
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/* Reset file pointer to beginning or open file. */ \
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status = internal_setent (keep_stream); \
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\
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if (status == NSS_STATUS_SUCCESS) \
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{ \
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/* Tell getent function that we have repositioned the file pointer. */ \
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last_use = getby; \
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\
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while ((status = internal_getent (result, buffer, buflen, errnop \
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H_ERRNO_ARG EXTRA_ARGS_VALUE)) \
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== NSS_STATUS_SUCCESS) \
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{ break_if_match } \
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\
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if (! keep_stream) \
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internal_endent (); \
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} \
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keep_stream is initialized from the stayopen flag in internal_setent.
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internal_setent is called from the set*ent implementation as:
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status = internal_setent (stayopen);
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However, for non-host database, this flag is always 0, per the
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STAYOPEN magic in nss/getXXent_r.c.
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Thus, the fix is this:
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- status = internal_setent (stayopen);
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+ status = internal_setent (1);
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This is not a behavioral change even for the hosts database (where the
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application can specify the stayopen flag) because with a call to
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sethostent(0), the file handle is still not closed in the
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implementation of gethostent.
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---
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ChangeLog | 8 ++++
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NEWS | 12 +++--
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nss/Makefile | 2 +-
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nss/nss_files/files-XXX.c | 2 +-
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nss/tst-nss-getpwent.c | 118 ++++++++++++++++++++++++++++++++++++++++++++++
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5 files changed, 136 insertions(+), 6 deletions(-)
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create mode 100644 nss/tst-nss-getpwent.c
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diff --git a/nss/Makefile b/nss/Makefile
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index d75dad2..65ab7b5 100644
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--- a/nss/Makefile
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+++ b/nss/Makefile
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@@ -47,7 +47,7 @@ install-bin := getent makedb
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makedb-modules = xmalloc hash-string
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extra-objs += $(makedb-modules:=.o)
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-tests = test-netdb tst-nss-test1 test-digits-dots
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+tests = test-netdb tst-nss-test1 test-digits-dots tst-nss-getpwent
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xtests = bug-erange
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# Specify rules for the nss_* modules. We have some services.
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diff --git a/nss/nss_files/files-XXX.c b/nss/nss_files/files-XXX.c
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index a7a45e5..a7ce5ea 100644
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--- a/nss/nss_files/files-XXX.c
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+++ b/nss/nss_files/files-XXX.c
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@@ -134,7 +134,7 @@ CONCAT(_nss_files_set,ENTNAME) (int stayopen)
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__libc_lock_lock (lock);
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- status = internal_setent (stayopen);
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+ status = internal_setent (1);
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if (status == NSS_STATUS_SUCCESS && fgetpos (stream, &position) < 0)
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{
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diff --git a/nss/tst-nss-getpwent.c b/nss/tst-nss-getpwent.c
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new file mode 100644
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index 0000000..f2e8abc
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--- /dev/null
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+++ b/nss/tst-nss-getpwent.c
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@@ -0,0 +1,118 @@
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+/* Copyright (C) 2015 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <http://www.gnu.org/licenses/>. */
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+
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+#include <pwd.h>
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+#include <stdbool.h>
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+#include <stdio.h>
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+#include <stdlib.h>
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+#include <string.h>
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+
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+int
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+do_test (void)
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+{
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+ /* Count the number of entries in the password database, and fetch
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+ data from the first and last entries. */
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+ size_t count = 0;
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+ struct passwd * pw;
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+ char *first_name = NULL;
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+ uid_t first_uid = 0;
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+ char *last_name = NULL;
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+ uid_t last_uid = 0;
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+ setpwent ();
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+ while ((pw = getpwent ()) != NULL)
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+ {
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+ if (first_name == NULL)
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+ {
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+ first_name = strdup (pw->pw_name);
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+ if (first_name == NULL)
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+ {
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+ printf ("strdup: %m\n");
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+ return 1;
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+ }
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+ first_uid = pw->pw_uid;
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+ }
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+
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+ free (last_name);
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+ last_name = strdup (pw->pw_name);
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+ if (last_name == NULL)
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+ {
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+ printf ("strdup: %m\n");
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+ return 1;
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+ }
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+ last_uid = pw->pw_uid;
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+ ++count;
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+ }
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+ endpwent ();
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+
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+ if (count == 0)
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+ {
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+ printf ("No entries in the password database.\n");
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+ return 0;
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+ }
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+
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+ /* Try again, this time interleaving with name-based and UID-based
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+ lookup operations. The counts do not match if the interleaved
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+ lookups affected the enumeration. */
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+ size_t new_count = 0;
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+ setpwent ();
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+ while ((pw = getpwent ()) != NULL)
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+ {
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+ if (new_count == count)
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+ {
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+ printf ("Additional entry in the password database.\n");
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+ return 1;
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+ }
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+ ++new_count;
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+ struct passwd *pw2 = getpwnam (first_name);
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+ if (pw2 == NULL)
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+ {
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+ printf ("getpwnam (%s) failed: %m\n", first_name);
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+ return 1;
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+ }
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+ pw2 = getpwnam (last_name);
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+ if (pw2 == NULL)
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+ {
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+ printf ("getpwnam (%s) failed: %m\n", last_name);
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+ return 1;
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+ }
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+ pw2 = getpwuid (first_uid);
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+ if (pw2 == NULL)
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+ {
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+ printf ("getpwuid (%llu) failed: %m\n",
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+ (unsigned long long) first_uid);
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+ return 1;
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+ }
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+ pw2 = getpwuid (last_uid);
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+ if (pw2 == NULL)
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+ {
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+ printf ("getpwuid (%llu) failed: %m\n",
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+ (unsigned long long) last_uid);
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+ return 1;
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+ }
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+ }
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+ endpwent ();
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+ if (new_count < count)
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+ {
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+ printf ("Missing entry in the password database.\n");
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+ return 1;
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+ }
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+
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+ return 0;
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+}
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+
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+#define TEST_FUNCTION do_test ()
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+#include "../test-skeleton.c"
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