From 99135114ba23c3110b7e4e650fabdc5e639746b7 Mon Sep 17 00:00:00 2001 From: DJ Delorie Date: Fri, 28 Jun 2019 18:30:00 -0500 Subject: [PATCH] nss_db: fix endent wrt NULL mappings [BZ #24695] [BZ #24696] nss_db allows for getpwent et al to be called without a set*ent, but it only works once. After the last get*ent a set*ent is required to restart, because the end*ent did not properly reset the module. Resetting it to NULL allows for a proper restart. If the database doesn't exist, however, end*ent erroniously called munmap which set errno. The test case runs "makedb" inside the testroot, so needs selinux DSOs installed. --- ChangeLog | 16 +++++ nss/Makefile | 4 +- nss/nss_db/db-open.c | 6 +- nss/tst-nss-db-endgrent.c | 54 +++++++++++++++ .../etc/nsswitch.conf | 1 + nss/tst-nss-db-endpwent.c | 66 +++++++++++++++++++ .../etc/nsswitch.conf | 1 + nss/tst-nss-db-endpwent.root/var/db/passwd.in | 4 ++ support/Makefile | 5 ++ support/links-dso-program-c.c | 17 +++++ support/links-dso-program.cc | 17 +++++ 11 files changed, 189 insertions(+), 2 deletions(-) create mode 100644 nss/tst-nss-db-endgrent.c create mode 100644 nss/tst-nss-db-endgrent.root/etc/nsswitch.conf create mode 100644 nss/tst-nss-db-endpwent.c create mode 100644 nss/tst-nss-db-endpwent.root/etc/nsswitch.conf create mode 100644 nss/tst-nss-db-endpwent.root/var/db/passwd.in diff --git a/ChangeLog b/ChangeLog index dd99d9883b..d42f4faeb0 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,19 @@ +2019-07-10 DJ Delorie + Sergei Trofimovich + + [BZ #24696] + [BZ #24695] + * nss/nss_db/db-open.c (internal_endent): Protect against NULL + mappings. + * nss/tst-nss-db-endgrent.c: New. + * nss/tst-nss-db-endgrent.root: New. + * nss/tst-nss-db-endpwent.c: New. + * nss/tst-nss-db-endpwent.root: New. + * nss/Makefile: Add new tests. + * support/links-dso-program-c.c: Add selinux dependency. + * support/links-dso-program.cc: Add selinux dependency. + * support/Makefile: Build those with -lselinux if enabled. + 2019-07-10 Szabolcs Nagy * sysdeps/aarch64/dl-machine.h (elf_machine_runtime_setup): Remove the diff --git a/nss/Makefile b/nss/Makefile index 95081bddc5..a15c3b7d90 100644 --- a/nss/Makefile +++ b/nss/Makefile @@ -61,7 +61,9 @@ xtests = bug-erange tests-container = \ tst-nss-test3 \ - tst-nss-files-hosts-long + tst-nss-files-hosts-long \ + tst-nss-db-endpwent \ + tst-nss-db-endgrent # Tests which need libdl ifeq (yes,$(build-shared)) diff --git a/nss/nss_db/db-open.c b/nss/nss_db/db-open.c index 8a83d6b930..3fa11e9ab0 100644 --- a/nss/nss_db/db-open.c +++ b/nss/nss_db/db-open.c @@ -63,5 +63,9 @@ internal_setent (const char *file, struct nss_db_map *mapping) void internal_endent (struct nss_db_map *mapping) { - munmap (mapping->header, mapping->len); + if (mapping->header != NULL) + { + munmap (mapping->header, mapping->len); + mapping->header = NULL; + } } diff --git a/nss/tst-nss-db-endgrent.c b/nss/tst-nss-db-endgrent.c new file mode 100644 index 0000000000..367cc6c901 --- /dev/null +++ b/nss/tst-nss-db-endgrent.c @@ -0,0 +1,54 @@ +/* Test for endgrent changing errno for BZ #24696 + Copyright (C) 2019 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 + +/* The following test verifies that if the db NSS Service is initialized + with no database (getgrent), that a subsequent closure (endgrent) does + not set errno. In the case of the db service it is not an error to close + the service and so it should not set errno. */ + +static int +do_test (void) +{ + /* Just make sure it's not there, although usually it won't be. */ + unlink ("/var/db/group.db"); + + /* This, in conjunction with the testroot's nsswitch.conf, causes + the nss_db module to be "connected" and initialized - but the + testroot has no group.db, so no mapping will be created. */ + getgrent (); + + errno = 0; + + /* Before the fix, this would call munmap (NULL) and set errno. */ + endgrent (); + + if (errno != 0) + FAIL_EXIT1 ("endgrent set errno to %d\n", errno); + + return 0; +} +#include diff --git a/nss/tst-nss-db-endgrent.root/etc/nsswitch.conf b/nss/tst-nss-db-endgrent.root/etc/nsswitch.conf new file mode 100644 index 0000000000..21471df94f --- /dev/null +++ b/nss/tst-nss-db-endgrent.root/etc/nsswitch.conf @@ -0,0 +1 @@ +group : db files diff --git a/nss/tst-nss-db-endpwent.c b/nss/tst-nss-db-endpwent.c new file mode 100644 index 0000000000..cb85410b7c --- /dev/null +++ b/nss/tst-nss-db-endpwent.c @@ -0,0 +1,66 @@ +/* Test for endpwent->getpwent crash for BZ #24695 + Copyright (C) 2019 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 + +/* It is entirely allowed to start with a getpwent call without + resetting the state of the service via a call to setpwent. + You can also call getpwent more times than you have entries in + the service, and it should not fail. This test iteratates the + database once, gets to the end, and then attempts a second + iteration to look for crashes. */ + +static void +try_it (void) +{ + struct passwd *pw; + + /* setpwent is intentionally omitted here. The first call to + getpwent detects that it's first and initializes. The second + time try_it is called, this "first call" was not detected before + the fix, and getpwent would crash. */ + + while ((pw = getpwent ()) != NULL) + ; + + /* We only care if this segfaults or not. */ + endpwent (); +} + +static int +do_test (void) +{ + char *cmd; + + cmd = xasprintf ("%s/makedb -o /var/db/passwd.db /var/db/passwd.in", + support_bindir_prefix); + system (cmd); + free (cmd); + + try_it (); + try_it (); + + return 0; +} +#include diff --git a/nss/tst-nss-db-endpwent.root/etc/nsswitch.conf b/nss/tst-nss-db-endpwent.root/etc/nsswitch.conf new file mode 100644 index 0000000000..593ffc564a --- /dev/null +++ b/nss/tst-nss-db-endpwent.root/etc/nsswitch.conf @@ -0,0 +1 @@ +passwd: db diff --git a/nss/tst-nss-db-endpwent.root/var/db/passwd.in b/nss/tst-nss-db-endpwent.root/var/db/passwd.in new file mode 100644 index 0000000000..98f39126ef --- /dev/null +++ b/nss/tst-nss-db-endpwent.root/var/db/passwd.in @@ -0,0 +1,4 @@ +.root root:x:0:0:root:/root:/bin/bash +=0 root:x:0:0:root:/root:/bin/bash +.bin bin:x:1:1:bin:/bin:/sbin/nologin +=1 bin:x:1:1:bin:/bin:/sbin/nologin diff --git a/support/Makefile b/support/Makefile index 56c1ed43bb..ab66913a02 100644 --- a/support/Makefile +++ b/support/Makefile @@ -191,6 +191,11 @@ LINKS_DSO_PROGRAM = links-dso-program LDLIBS-links-dso-program = -lstdc++ -lgcc -lgcc_s $(libunwind) endif +ifeq (yes,$(have-selinux)) +LDLIBS-$(LINKS_DSO_PROGRAM) += -lselinux +endif + + LDLIBS-test-container = $(libsupport) others += test-container diff --git a/support/links-dso-program-c.c b/support/links-dso-program-c.c index d28a28a0d0..5fcbab2c17 100644 --- a/support/links-dso-program-c.c +++ b/support/links-dso-program-c.c @@ -1,9 +1,26 @@ #include +/* makedb needs selinux dso's. */ +#ifdef HAVE_SELINUX +# include +#endif + +/* The purpose of this file is to indicate to the build system which + shared objects need to be copied into the testroot, such as gcc or + selinux support libraries. This program is never executed, only + scanned for dependencies on shared objects, so the code below may + seem weird - it's written to survive gcc optimization and force + such dependencies. +*/ + int main (int argc, char **argv) { /* Complexity to keep gcc from optimizing this away. */ printf ("This is a test %s.\n", argc > 1 ? argv[1] : "null"); +#ifdef HAVE_SELINUX + /* This exists to force libselinux.so to be required. */ + printf ("selinux %d\n", is_selinux_enabled ()); +#endif return 0; } diff --git a/support/links-dso-program.cc b/support/links-dso-program.cc index dba6976c06..4bc2411086 100644 --- a/support/links-dso-program.cc +++ b/support/links-dso-program.cc @@ -1,11 +1,28 @@ #include +/* makedb needs selinux dso's. */ +#ifdef HAVE_SELINUX +# include +#endif + using namespace std; +/* The purpose of this file is to indicate to the build system which + shared objects need to be copied into the testroot, such as gcc or + selinux support libraries. This program is never executed, only + scanned for dependencies on shared objects, so the code below may + seem weird - it's written to survive gcc optimization and force + such dependencies. +*/ + int main (int argc, char **argv) { /* Complexity to keep gcc from optimizing this away. */ cout << (argc > 1 ? argv[1] : "null"); +#ifdef HAVE_SELINUX + /* This exists to force libselinux.so to be required. */ + cout << "selinux " << is_selinux_enabled (); +#endif return 0; }