glibc/nss/nss_database.h
DJ Delorie 9b456c5da9 nss: fix nss_database_lookup2's alternate handling [BZ #27416]
__nss_database_lookup2's extra arguments were left unused in the
nsswitch reloading patch set; this broke compat (default config
ignored) and shadow files (secondary name ignored) which relies on
these fallbacks.

This patch adds in the previous behavior by correcting the
initialization of the database list to reflect the fallbacks.  This
means that the nss_database_lookup2 interface no longer needs to be
passed the fallback info, so API and callers were adjusted.

Since all callers needed to be edited anyway, the calls were changed
from __nss_database_lookup2 to the faster __nss_database_get.  This
was an intended optimization which was deferred during the initial
lookup changes to avoid touching so many files.

The test case verifies that compat targets work (passwd) and that the
default configuration works (group).  Tested on x86-64.
2021-03-09 14:34:50 -05:00

88 lines
3.3 KiB
C

/* Mapping NSS services to action lists.
Copyright (C) 2020-2021 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/>. */
#ifndef _NSS_DATABASE_H
#define _NSS_DATABASE_H
#include <file_change_detection.h>
/* Each "line" in nsswitch.conf maps a supported database (example:
passwd) to one or more name service providers (example: files dns).
Internally, each name service provider (example: dns) is a
dynamically loadable module (i.e. libnss_dns.so), managed by
nss_module.h. The sequence of providers and rules (example: files
[SUCCESS=RETURN] dns) is mapped by nss_action.h to a cached entry
which encodes the sequence of modules and rules. Keeping track of
all supported databases and their corresponding actions is done
here.
The key entry is __nss_database_get, which provides a set of
actions which can be used with nss_lookup_function() and
nss_next(). Callers should assume that these functions are fast,
and should not cache the result longer than needed. */
#include "nss_action.h"
/* The enumeration literal in enum nss_database for the database NAME
(e.g., nss_database_hosts for hosts). */
#define NSS_DATABASE_LITERAL(name) nss_database_##name
enum nss_database
{
#define DEFINE_DATABASE(name) NSS_DATABASE_LITERAL (name),
#include "databases.def"
#undef DEFINE_DATABASE
/* Total number of databases. */
NSS_DATABASE_COUNT
};
/* Looks up the action list for DB and stores it in *ACTIONS. Returns
true on success or false on failure. Success can mean that
*ACTIONS is NULL. */
bool __nss_database_get (enum nss_database db, nss_action_list *actions);
libc_hidden_proto (__nss_database_get)
/* Like __nss_database_get, but does not reload /etc/nsswitch.conf
from disk. This assumes that there has been a previous successful
__nss_database_get call (which may not have returned any data). */
nss_action_list __nss_database_get_noreload (enum nss_database db)
attribute_hidden;
/* Called from __libc_freeres. */
void __nss_database_freeres (void) attribute_hidden;
/* Internal type. Exposed only for fork handling purposes. */
struct nss_database_data
{
struct file_change_detection nsswitch_conf;
nss_action_list services[NSS_DATABASE_COUNT];
int reload_disabled; /* Actually bool; int for atomic access. */
bool initialized;
};
/* Called by fork in the parent process, before forking. */
void __nss_database_fork_prepare_parent (struct nss_database_data *data)
attribute_hidden;
/* Called by fork in the new subprocess, after forking. */
void __nss_database_fork_subprocess (struct nss_database_data *data)
attribute_hidden;
#endif /* _NSS_DATABASE_H */