glibc/nss/nsswitch.c
Petr Vorel ae7a94e5e3 Remove --enable-obsolete-nsl configure flag
this means that *always* libnsl is only built as shared library for
backward compatibility and the NSS modules libnss_nis and libnss_nisplus
are not built at all, libnsl's headers aren't installed.

This compatibility is kept only for architectures and ABIs that have
been added in or before version 2.28.

Replacement implementations based on TIRPC, which additionally support
IPv6, are available from <https://github.com/thkukuk/>.

This change does not affect libnss_compat which does not depended
on libnsl since 2.27 and thus can be used without NIS.

libnsl code depends on Sun RPC, e.g. on --enable-obsolete-rpc (installed
libnsl headers use installed Sun RPC headers), which will be removed in
the following commit.
2020-07-08 17:25:57 +02:00

921 lines
23 KiB
C

/* Copyright (C) 1996-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
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 <ctype.h>
#include <dlfcn.h>
#include <errno.h>
#include <netdb.h>
#include <libc-lock.h>
#include <search.h>
#include <stdio.h>
#include <stdio_ext.h>
#include <stdlib.h>
#include <string.h>
#include <aliases.h>
#include <grp.h>
#include <netinet/ether.h>
#include <pwd.h>
#include <shadow.h>
#if !defined DO_STATIC_NSS || defined SHARED
# include <gnu/lib-names.h>
#endif
#include "nsswitch.h"
#include "../nscd/nscd_proto.h"
#include <sysdep.h>
#include <config.h>
/* Prototypes for the local functions. */
static name_database *nss_parse_file (const char *fname);
static name_database_entry *nss_getline (char *line);
static service_user *nss_parse_service_list (const char *line);
#if !defined DO_STATIC_NSS || defined SHARED
static service_library *nss_new_service (name_database *database,
const char *name);
#endif
/* Declare external database variables. */
#define DEFINE_DATABASE(name) \
service_user *__nss_##name##_database attribute_hidden; \
weak_extern (__nss_##name##_database)
#include "databases.def"
#undef DEFINE_DATABASE
/* Structure to map database name to variable. */
static const struct
{
const char name[10];
service_user **dbp;
} databases[] =
{
#define DEFINE_DATABASE(name) \
{ #name, &__nss_##name##_database },
#include "databases.def"
#undef DEFINE_DATABASE
};
#define ndatabases (sizeof (databases) / sizeof (databases[0]))
#ifdef USE_NSCD
/* Flags whether custom rules for database is set. */
bool __nss_database_custom[NSS_DBSIDX_max];
#endif
__libc_lock_define_initialized (static, lock)
#if !defined DO_STATIC_NSS || defined SHARED
/* String with revision number of the shared object files. */
static const char *const __nss_shlib_revision = LIBNSS_FILES_SO + 15;
#endif
/* The root of the whole data base. */
static name_database *service_table;
/* List of default service lists that were generated by glibc because
/etc/nsswitch.conf did not provide a value.
The list is only maintained so we can free such service lists in
__libc_freeres. */
static name_database_entry *defconfig_entries;
#if defined USE_NSCD && (!defined DO_STATIC_NSS || defined SHARED)
/* Nonzero if this is the nscd process. */
static bool is_nscd;
/* The callback passed to the init functions when nscd is used. */
static void (*nscd_init_cb) (size_t, struct traced_file *);
#endif
/* -1 == database not found
0 == database entry pointer stored */
int
__nss_database_lookup2 (const char *database, const char *alternate_name,
const char *defconfig, service_user **ni)
{
/* Prevent multiple threads to change the service table. */
__libc_lock_lock (lock);
/* Reconsider database variable in case some other thread called
`__nss_configure_lookup' while we waited for the lock. */
if (*ni != NULL)
{
__libc_lock_unlock (lock);
return 0;
}
/* Are we initialized yet? */
if (service_table == NULL)
/* Read config file. */
service_table = nss_parse_file (_PATH_NSSWITCH_CONF);
/* Test whether configuration data is available. */
if (service_table != NULL)
{
/* Return first `service_user' entry for DATABASE. */
name_database_entry *entry;
/* XXX Could use some faster mechanism here. But each database is
only requested once and so this might not be critical. */
for (entry = service_table->entry; entry != NULL; entry = entry->next)
if (strcmp (database, entry->name) == 0)
*ni = entry->service;
if (*ni == NULL && alternate_name != NULL)
/* We haven't found an entry so far. Try to find it with the
alternative name. */
for (entry = service_table->entry; entry != NULL; entry = entry->next)
if (strcmp (alternate_name, entry->name) == 0)
*ni = entry->service;
}
/* No configuration data is available, either because nsswitch.conf
doesn't exist or because it doesn't have a line for this database.
DEFCONFIG specifies the default service list for this database,
or null to use the most common default. */
if (*ni == NULL)
{
*ni = nss_parse_service_list (defconfig ?: "files");
if (*ni != NULL)
{
/* Record the memory we've just allocated in defconfig_entries list,
so we can free it later. */
name_database_entry *entry;
/* Allocate ENTRY plus size of name (1 here). */
entry = (name_database_entry *) malloc (sizeof (*entry) + 1);
if (entry != NULL)
{
entry->next = defconfig_entries;
entry->service = *ni;
entry->name[0] = '\0';
defconfig_entries = entry;
}
}
}
__libc_lock_unlock (lock);
return *ni != NULL ? 0 : -1;
}
libc_hidden_def (__nss_database_lookup2)
/* -1 == not found
0 == function found
1 == finished */
int
__nss_lookup (service_user **ni, const char *fct_name, const char *fct2_name,
void **fctp)
{
*fctp = __nss_lookup_function (*ni, fct_name);
if (*fctp == NULL && fct2_name != NULL)
*fctp = __nss_lookup_function (*ni, fct2_name);
while (*fctp == NULL
&& nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_CONTINUE
&& (*ni)->next != NULL)
{
*ni = (*ni)->next;
*fctp = __nss_lookup_function (*ni, fct_name);
if (*fctp == NULL && fct2_name != NULL)
*fctp = __nss_lookup_function (*ni, fct2_name);
}
return *fctp != NULL ? 0 : (*ni)->next == NULL ? 1 : -1;
}
libc_hidden_def (__nss_lookup)
/* -1 == not found
0 == adjusted for next function
1 == finished */
int
__nss_next2 (service_user **ni, const char *fct_name, const char *fct2_name,
void **fctp, int status, int all_values)
{
if (all_values)
{
if (nss_next_action (*ni, NSS_STATUS_TRYAGAIN) == NSS_ACTION_RETURN
&& nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_RETURN
&& nss_next_action (*ni, NSS_STATUS_NOTFOUND) == NSS_ACTION_RETURN
&& nss_next_action (*ni, NSS_STATUS_SUCCESS) == NSS_ACTION_RETURN)
return 1;
}
else
{
/* This is really only for debugging. */
if (__builtin_expect (NSS_STATUS_TRYAGAIN > status
|| status > NSS_STATUS_RETURN, 0))
__libc_fatal ("Illegal status in __nss_next.\n");
if (nss_next_action (*ni, status) == NSS_ACTION_RETURN)
return 1;
}
if ((*ni)->next == NULL)
return -1;
do
{
*ni = (*ni)->next;
*fctp = __nss_lookup_function (*ni, fct_name);
if (*fctp == NULL && fct2_name != NULL)
*fctp = __nss_lookup_function (*ni, fct2_name);
}
while (*fctp == NULL
&& nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_CONTINUE
&& (*ni)->next != NULL);
return *fctp != NULL ? 0 : -1;
}
libc_hidden_def (__nss_next2)
int
__nss_configure_lookup (const char *dbname, const char *service_line)
{
service_user *new_db;
size_t cnt;
for (cnt = 0; cnt < ndatabases; ++cnt)
{
int cmp = strcmp (dbname, databases[cnt].name);
if (cmp == 0)
break;
if (cmp < 0)
{
__set_errno (EINVAL);
return -1;
}
}
if (cnt == ndatabases)
{
__set_errno (EINVAL);
return -1;
}
/* Test whether it is really used. */
if (databases[cnt].dbp == NULL)
/* Nothing to do, but we could do. */
return 0;
/* Try to generate new data. */
new_db = nss_parse_service_list (service_line);
if (new_db == NULL)
{
/* Illegal service specification. */
__set_errno (EINVAL);
return -1;
}
/* Prevent multiple threads to change the service table. */
__libc_lock_lock (lock);
/* Install new rules. */
*databases[cnt].dbp = new_db;
#ifdef USE_NSCD
__nss_database_custom[cnt] = true;
#endif
__libc_lock_unlock (lock);
return 0;
}
/* Comparison function for searching NI->known tree. */
static int
known_compare (const void *p1, const void *p2)
{
return p1 == p2 ? 0 : strcmp (*(const char *const *) p1,
*(const char *const *) p2);
}
#if !defined DO_STATIC_NSS || defined SHARED
/* Load library. */
static int
nss_load_library (service_user *ni)
{
if (ni->library == NULL)
{
/* This service has not yet been used. Fetch the service
library for it, creating a new one if need be. If there
is no service table from the file, this static variable
holds the head of the service_library list made from the
default configuration. */
static name_database default_table;
ni->library = nss_new_service (service_table ?: &default_table,
ni->name);
if (ni->library == NULL)
return -1;
}
if (ni->library->lib_handle == NULL)
{
/* Load the shared library. */
size_t shlen = (7 + strlen (ni->name) + 3
+ strlen (__nss_shlib_revision) + 1);
int saved_errno = errno;
char shlib_name[shlen];
/* Construct shared object name. */
__stpcpy (__stpcpy (__stpcpy (__stpcpy (shlib_name,
"libnss_"),
ni->name),
".so"),
__nss_shlib_revision);
ni->library->lib_handle = __libc_dlopen (shlib_name);
if (ni->library->lib_handle == NULL)
{
/* Failed to load the library. */
ni->library->lib_handle = (void *) -1l;
__set_errno (saved_errno);
}
# ifdef USE_NSCD
else if (is_nscd)
{
/* Call the init function when nscd is used. */
size_t initlen = (5 + strlen (ni->name)
+ strlen ("_init") + 1);
char init_name[initlen];
/* Construct the init function name. */
__stpcpy (__stpcpy (__stpcpy (init_name,
"_nss_"),
ni->name),
"_init");
/* Find the optional init function. */
void (*ifct) (void (*) (size_t, struct traced_file *))
= __libc_dlsym (ni->library->lib_handle, init_name);
if (ifct != NULL)
{
void (*cb) (size_t, struct traced_file *) = nscd_init_cb;
# ifdef PTR_DEMANGLE
PTR_DEMANGLE (cb);
# endif
ifct (cb);
}
}
# endif
}
return 0;
}
#endif
void *
__nss_lookup_function (service_user *ni, const char *fct_name)
{
void **found, *result;
/* We now modify global data. Protect it. */
__libc_lock_lock (lock);
/* Search the tree of functions previously requested. Data in the
tree are `known_function' structures, whose first member is a
`const char *', the lookup key. The search returns a pointer to
the tree node structure; the first member of the is a pointer to
our structure (i.e. what will be a `known_function'); since the
first member of that is the lookup key string, &FCT_NAME is close
enough to a pointer to our structure to use as a lookup key that
will be passed to `known_compare' (above). */
found = __tsearch (&fct_name, &ni->known, &known_compare);
if (found == NULL)
/* This means out-of-memory. */
result = NULL;
else if (*found != &fct_name)
{
/* The search found an existing structure in the tree. */
result = ((known_function *) *found)->fct_ptr;
#ifdef PTR_DEMANGLE
PTR_DEMANGLE (result);
#endif
}
else
{
/* This name was not known before. Now we have a node in the tree
(in the proper sorted position for FCT_NAME) that points to
&FCT_NAME instead of any real `known_function' structure.
Allocate a new structure and fill it in. */
known_function *known = malloc (sizeof *known);
if (! known)
{
#if !defined DO_STATIC_NSS || defined SHARED
remove_from_tree:
#endif
/* Oops. We can't instantiate this node properly.
Remove it from the tree. */
__tdelete (&fct_name, &ni->known, &known_compare);
free (known);
result = NULL;
}
else
{
/* Point the tree node at this new structure. */
*found = known;
known->fct_name = fct_name;
#if !defined DO_STATIC_NSS || defined SHARED
/* Load the appropriate library. */
if (nss_load_library (ni) != 0)
/* This only happens when out of memory. */
goto remove_from_tree;
if (ni->library->lib_handle == (void *) -1l)
/* Library not found => function not found. */
result = NULL;
else
{
/* Get the desired function. */
size_t namlen = (5 + strlen (ni->name) + 1
+ strlen (fct_name) + 1);
char name[namlen];
/* Construct the function name. */
__stpcpy (__stpcpy (__stpcpy (__stpcpy (name, "_nss_"),
ni->name),
"_"),
fct_name);
/* Look up the symbol. */
result = __libc_dlsym (ni->library->lib_handle, name);
}
#else
/* We can't get function address dynamically in static linking. */
{
# define DEFINE_ENT(h,nm) \
{ #h"_get"#nm"ent_r", _nss_##h##_get##nm##ent_r }, \
{ #h"_end"#nm"ent", _nss_##h##_end##nm##ent }, \
{ #h"_set"#nm"ent", _nss_##h##_set##nm##ent },
# define DEFINE_GET(h,nm) \
{ #h"_get"#nm"_r", _nss_##h##_get##nm##_r },
# define DEFINE_GETBY(h,nm,ky) \
{ #h"_get"#nm"by"#ky"_r", _nss_##h##_get##nm##by##ky##_r },
static struct fct_tbl { const char *fname; void *fp; } *tp, tbl[] =
{
# include "function.def"
{ NULL, NULL }
};
size_t namlen = (5 + strlen (ni->name) + 1
+ strlen (fct_name) + 1);
char name[namlen];
/* Construct the function name. */
__stpcpy (__stpcpy (__stpcpy (name, ni->name),
"_"),
fct_name);
result = NULL;
for (tp = &tbl[0]; tp->fname; tp++)
if (strcmp (tp->fname, name) == 0)
{
result = tp->fp;
break;
}
}
#endif
/* Remember function pointer for later calls. Even if null, we
record it so a second try needn't search the library again. */
known->fct_ptr = result;
#ifdef PTR_MANGLE
PTR_MANGLE (known->fct_ptr);
#endif
}
}
/* Remove the lock. */
__libc_lock_unlock (lock);
return result;
}
libc_hidden_def (__nss_lookup_function)
static name_database *
nss_parse_file (const char *fname)
{
FILE *fp;
name_database *result;
name_database_entry *last;
char *line;
size_t len;
/* Open the configuration file. */
fp = fopen (fname, "rce");
if (fp == NULL)
return NULL;
/* No threads use this stream. */
__fsetlocking (fp, FSETLOCKING_BYCALLER);
result = (name_database *) malloc (sizeof (name_database));
if (result == NULL)
{
fclose (fp);
return NULL;
}
result->entry = NULL;
result->library = NULL;
last = NULL;
line = NULL;
len = 0;
do
{
name_database_entry *this;
ssize_t n;
n = __getline (&line, &len, fp);
if (n < 0)
break;
if (line[n - 1] == '\n')
line[n - 1] = '\0';
/* Because the file format does not know any form of quoting we
can search forward for the next '#' character and if found
make it terminating the line. */
*__strchrnul (line, '#') = '\0';
/* If the line is blank it is ignored. */
if (line[0] == '\0')
continue;
/* Each line completely specifies the actions for a database. */
this = nss_getline (line);
if (this != NULL)
{
if (last != NULL)
last->next = this;
else
result->entry = this;
last = this;
}
}
while (!__feof_unlocked (fp));
/* Free the buffer. */
free (line);
/* Close configuration file. */
fclose (fp);
return result;
}
/* Read the source names:
`( <source> ( "[" "!"? (<status> "=" <action> )+ "]" )? )*'
*/
static service_user *
nss_parse_service_list (const char *line)
{
service_user *result = NULL, **nextp = &result;
while (1)
{
service_user *new_service;
const char *name;
while (isspace (line[0]))
++line;
if (line[0] == '\0')
/* No source specified. */
return result;
/* Read <source> identifier. */
name = line;
while (line[0] != '\0' && !isspace (line[0]) && line[0] != '[')
++line;
if (name == line)
return result;
new_service = (service_user *) malloc (sizeof (service_user)
+ (line - name + 1));
if (new_service == NULL)
return result;
*((char *) __mempcpy (new_service->name, name, line - name)) = '\0';
/* Set default actions. */
new_service->actions[2 + NSS_STATUS_TRYAGAIN] = NSS_ACTION_CONTINUE;
new_service->actions[2 + NSS_STATUS_UNAVAIL] = NSS_ACTION_CONTINUE;
new_service->actions[2 + NSS_STATUS_NOTFOUND] = NSS_ACTION_CONTINUE;
new_service->actions[2 + NSS_STATUS_SUCCESS] = NSS_ACTION_RETURN;
new_service->actions[2 + NSS_STATUS_RETURN] = NSS_ACTION_RETURN;
new_service->library = NULL;
new_service->known = NULL;
new_service->next = NULL;
while (isspace (line[0]))
++line;
if (line[0] == '[')
{
/* Read criterions. */
do
++line;
while (line[0] != '\0' && isspace (line[0]));
do
{
int not;
enum nss_status status;
lookup_actions action;
/* Grok ! before name to mean all statii but that one. */
not = line[0] == '!';
if (not)
++line;
/* Read status name. */
name = line;
while (line[0] != '\0' && !isspace (line[0]) && line[0] != '='
&& line[0] != ']')
++line;
/* Compare with known statii. */
if (line - name == 7)
{
if (__strncasecmp (name, "SUCCESS", 7) == 0)
status = NSS_STATUS_SUCCESS;
else if (__strncasecmp (name, "UNAVAIL", 7) == 0)
status = NSS_STATUS_UNAVAIL;
else
goto finish;
}
else if (line - name == 8)
{
if (__strncasecmp (name, "NOTFOUND", 8) == 0)
status = NSS_STATUS_NOTFOUND;
else if (__strncasecmp (name, "TRYAGAIN", 8) == 0)
status = NSS_STATUS_TRYAGAIN;
else
goto finish;
}
else
goto finish;
while (isspace (line[0]))
++line;
if (line[0] != '=')
goto finish;
do
++line;
while (isspace (line[0]));
name = line;
while (line[0] != '\0' && !isspace (line[0]) && line[0] != '='
&& line[0] != ']')
++line;
if (line - name == 6 && __strncasecmp (name, "RETURN", 6) == 0)
action = NSS_ACTION_RETURN;
else if (line - name == 8
&& __strncasecmp (name, "CONTINUE", 8) == 0)
action = NSS_ACTION_CONTINUE;
else if (line - name == 5
&& __strncasecmp (name, "MERGE", 5) == 0)
action = NSS_ACTION_MERGE;
else
goto finish;
if (not)
{
/* Save the current action setting for this status,
set them all to the given action, and reset this one. */
const lookup_actions save = new_service->actions[2 + status];
new_service->actions[2 + NSS_STATUS_TRYAGAIN] = action;
new_service->actions[2 + NSS_STATUS_UNAVAIL] = action;
new_service->actions[2 + NSS_STATUS_NOTFOUND] = action;
new_service->actions[2 + NSS_STATUS_SUCCESS] = action;
new_service->actions[2 + status] = save;
}
else
new_service->actions[2 + status] = action;
/* Skip white spaces. */
while (isspace (line[0]))
++line;
}
while (line[0] != ']');
/* Skip the ']'. */
++line;
}
*nextp = new_service;
nextp = &new_service->next;
continue;
finish:
free (new_service);
return result;
}
}
static name_database_entry *
nss_getline (char *line)
{
const char *name;
name_database_entry *result;
size_t len;
/* Ignore leading white spaces. ATTENTION: this is different from
what is implemented in Solaris. The Solaris man page says a line
beginning with a white space character is ignored. We regard
this as just another misfeature in Solaris. */
while (isspace (line[0]))
++line;
/* Recognize `<database> ":"'. */
name = line;
while (line[0] != '\0' && !isspace (line[0]) && line[0] != ':')
++line;
if (line[0] == '\0' || name == line)
/* Syntax error. */
return NULL;
*line++ = '\0';
len = strlen (name) + 1;
result = (name_database_entry *) malloc (sizeof (name_database_entry) + len);
if (result == NULL)
return NULL;
/* Save the database name. */
memcpy (result->name, name, len);
/* Parse the list of services. */
result->service = nss_parse_service_list (line);
result->next = NULL;
return result;
}
#if !defined DO_STATIC_NSS || defined SHARED
static service_library *
nss_new_service (name_database *database, const char *name)
{
service_library **currentp = &database->library;
while (*currentp != NULL)
{
if (strcmp ((*currentp)->name, name) == 0)
return *currentp;
currentp = &(*currentp)->next;
}
/* We have to add the new service. */
*currentp = (service_library *) malloc (sizeof (service_library));
if (*currentp == NULL)
return NULL;
(*currentp)->name = name;
(*currentp)->lib_handle = NULL;
(*currentp)->next = NULL;
return *currentp;
}
#endif
#if defined SHARED && defined USE_NSCD
/* Load all libraries for the service. */
static void
nss_load_all_libraries (const char *service, const char *def)
{
service_user *ni = NULL;
if (__nss_database_lookup2 (service, NULL, def, &ni) == 0)
while (ni != NULL)
{
nss_load_library (ni);
ni = ni->next;
}
}
/* Called by nscd and nscd alone. */
void
__nss_disable_nscd (void (*cb) (size_t, struct traced_file *))
{
# ifdef PTR_MANGLE
PTR_MANGLE (cb);
# endif
nscd_init_cb = cb;
is_nscd = true;
/* Find all the relevant modules so that the init functions are called. */
nss_load_all_libraries ("passwd", "files");
nss_load_all_libraries ("group", "files");
nss_load_all_libraries ("hosts", "dns [!UNAVAIL=return] files");
nss_load_all_libraries ("services", NULL);
/* Disable all uses of NSCD. */
__nss_not_use_nscd_passwd = -1;
__nss_not_use_nscd_group = -1;
__nss_not_use_nscd_hosts = -1;
__nss_not_use_nscd_services = -1;
__nss_not_use_nscd_netgroup = -1;
}
#endif
static void
free_database_entries (name_database_entry *entry)
{
while (entry != NULL)
{
name_database_entry *olde = entry;
service_user *service = entry->service;
while (service != NULL)
{
service_user *olds = service;
if (service->known != NULL)
__tdestroy (service->known, free);
service = service->next;
free (olds);
}
entry = entry->next;
free (olde);
}
}
/* Free all resources if necessary. */
libc_freeres_fn (free_defconfig)
{
name_database_entry *entry = defconfig_entries;
if (entry == NULL)
/* defconfig was not used. */
return;
/* Don't disturb ongoing other threads (if there are any). */
defconfig_entries = NULL;
free_database_entries (entry);
}
libc_freeres_fn (free_mem)
{
name_database *top = service_table;
service_library *library;
if (top == NULL)
/* Maybe we have not read the nsswitch.conf file. */
return;
/* Don't disturb ongoing other threads (if there are any). */
service_table = NULL;
free_database_entries (top->entry);
library = top->library;
while (library != NULL)
{
service_library *oldl = library;
if (library->lib_handle && library->lib_handle != (void *) -1l)
__libc_dlclose (library->lib_handle);
library = library->next;
free (oldl);
}
free (top);
}