[2/3] Mark internal nss symbols with attribute_hidden [BZ #18822]
Commit Message
On Sun, Aug 20, 2017 at 1:08 AM, Florian Weimer <fw@deneb.enyo.de> wrote:
> * H. J. Lu:
>
>> extern service_user *__nss_group_database attribute_hidden;
>> -service_user *__nss_initgroups_database;
>> +service_user *__nss_initgroups_database attribute_hidden;
>> static bool use_initgroups_entry;
>
> Please use DEFINE_DATABASE in nsswitch.h instead to generate all
> __nss_*_database declarations (and remove the declaration from
> nss/XXX-lookup.c).
Done.
>> diff --git a/nss/getXXent.c b/nss/getXXent.c
>> index aad374197f..31bd24b924 100644
>> --- a/nss/getXXent.c
>> +++ b/nss/getXXent.c
>> @@ -56,7 +56,7 @@
>> /* Prototype of the reentrant version. */
>> extern int INTERNAL (REENTRANT_GETNAME) (LOOKUP_TYPE *resbuf, char *buffer,
>> size_t buflen, LOOKUP_TYPE **result
>> - H_ERRNO_PARM);
>> + H_ERRNO_PARM) attribute_hidden;
>
> Ideally, we should have a full complement of prototypes in include/,
> so that we get some type safety here. But until that, this part looks
> fine.
>
>> /* Flags whether custom rules for database is set. */
>> -extern bool __nss_database_custom[NSS_DBSIDX_max];
>> +extern bool __nss_database_custom[NSS_DBSIDX_max] attribute_hidden;
>
> The entire declaration should probably be guarded with #ifndef
> USE_NSCD because if the symbol is used from nscd, it would give wrong
> results.
Done.
Here is the updated patch. Tested on x86-64 with and without --disable-nscd.
OK for master?
Thanks.
Comments
On 08/20/2017 07:18 PM, H.J. Lu wrote:
> diff --git a/grp/initgroups.c b/grp/initgroups.c
> index 0d5b841796..0ffb5ceea1 100644
> --- a/grp/initgroups.c
> +++ b/grp/initgroups.c
> @@ -37,7 +37,6 @@ typedef enum nss_status (*initgroups_dyn_function) (const char *, gid_t,
> gid_t **, long int, int *);
>
> extern service_user *__nss_group_database attribute_hidden;
> -service_user *__nss_initgroups_database;
The declaration of __nss_group_database is no longer necessary, either.
I think these additional declarations can be removed as well"
nscd/gai.c:service_user *__nss_hosts_database;
posix/tst-rfc3484-2.c:service_user *__nss_hosts_database attribute_hidden;
posix/tst-rfc3484-3.c:service_user *__nss_hosts_database attribute_hidden;
posix/tst-rfc3484.c:service_user *__nss_hosts_database attribute_hidden;
sysdeps/posix/getaddrinfo.c:extern service_user *__nss_hosts_database
attribute_hidden;
Thanks,
Florian
From 6876672e67fb5e3a71139585ca4c16e43cfed70e Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Fri, 18 Aug 2017 12:27:59 -0700
Subject: [PATCH] Mark internal nss symbols with attribute_hidden [BZ #18822]
Mark internal nss symbols with attribute_hidden to allow direct access
within libc.so and libc.a without using GOT nor PLT.
Tested on x86-64 with and without --disable-nscd.
[BZ #18822]
* grp/initgroups.c (__nss_initgroups_database): Removed.
* nss/XXX-lookup.c (DATABASE_NAME_SYMBOL): Likewise.
* nss/getXXent.c (INTERNAL (REENTRANT_GETNAME)): Add
attribute_hidden.
* nss/nsswitch.c (__nss_database_custom): Define only if
USE_NSCD is defined.
(__nss_configure_lookup): Use __nss_database_custom only if
USE_NSCD is defined.
* nss/nsswitch.h (__nss_database_custom): Declare only if
USE_NSCD is defined. Add attribute_hidden.
(__nss_setent): Add attribute_hidden.
(__nss_endent): Likewise.
(__nss_getent_r): Likewise.
(__nss_getent): Likewise.
(DEFINE_DATABASE): Declare __nss_##arg##_database.
---
grp/initgroups.c | 1 -
nss/XXX-lookup.c | 2 --
nss/getXXent.c | 2 +-
nss/nsswitch.c | 4 ++++
nss/nsswitch.h | 23 +++++++++++++++--------
5 files changed, 20 insertions(+), 12 deletions(-)
@@ -37,7 +37,6 @@ typedef enum nss_status (*initgroups_dyn_function) (const char *, gid_t,
gid_t **, long int, int *);
extern service_user *__nss_group_database attribute_hidden;
-service_user *__nss_initgroups_database;
static bool use_initgroups_entry;
@@ -52,8 +52,6 @@
#define DEFAULT_CONFIG NULL
#endif
-service_user *DATABASE_NAME_SYMBOL attribute_hidden;
-
int
DB_LOOKUP_FCT (service_user **ni, const char *fct_name, const char *fct2_name,
void **fctp)
@@ -56,7 +56,7 @@
/* Prototype of the reentrant version. */
extern int INTERNAL (REENTRANT_GETNAME) (LOOKUP_TYPE *resbuf, char *buffer,
size_t buflen, LOOKUP_TYPE **result
- H_ERRNO_PARM);
+ H_ERRNO_PARM) attribute_hidden;
/* We need to protect the dynamic buffer handling. */
__libc_lock_define_initialized (static, lock);
@@ -73,8 +73,10 @@ static const struct
};
#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)
@@ -304,7 +306,9 @@ __nss_configure_lookup (const char *dbname, const char *service_line)
/* Install new rules. */
*databases[cnt].dbp = new_db;
+#ifdef USE_NSCD
__nss_database_custom[cnt] = true;
+#endif
__libc_lock_unlock (lock);
@@ -96,17 +96,19 @@ typedef struct name_database
} name_database;
+#ifdef USE_NSCD
/* Indices into DATABASES in nsswitch.c and __NSS_DATABASE_CUSTOM. */
enum
{
-#define DEFINE_DATABASE(arg) NSS_DBSIDX_##arg,
-#include "databases.def"
-#undef DEFINE_DATABASE
+# define DEFINE_DATABASE(arg) NSS_DBSIDX_##arg,
+# include "databases.def"
+# undef DEFINE_DATABASE
NSS_DBSIDX_max
};
/* Flags whether custom rules for database is set. */
-extern bool __nss_database_custom[NSS_DBSIDX_max];
+extern bool __nss_database_custom[NSS_DBSIDX_max] attribute_hidden;
+#endif
/* Warning for NSS functions, which don't require dlopen if glibc
was built with --enable-static-nss. */
@@ -180,11 +182,13 @@ extern void __nss_setent (const char *func_name,
db_lookup_function lookup_fct,
service_user **nip, service_user **startp,
service_user **last_nip, int stayon,
- int *stayon_tmp, int res);
+ int *stayon_tmp, int res)
+ attribute_hidden;
extern void __nss_endent (const char *func_name,
db_lookup_function lookup_fct,
service_user **nip, service_user **startp,
- service_user **last_nip, int res);
+ service_user **last_nip, int res)
+ attribute_hidden;
extern int __nss_getent_r (const char *getent_func_name,
const char *setent_func_name,
db_lookup_function lookup_fct,
@@ -192,10 +196,12 @@ extern int __nss_getent_r (const char *getent_func_name,
service_user **last_nip, int *stayon_tmp,
int res,
void *resbuf, char *buffer, size_t buflen,
- void **result, int *h_errnop);
+ void **result, int *h_errnop)
+ attribute_hidden;
extern void *__nss_getent (getent_r_function func,
void **resbuf, char **buffer, size_t buflen,
- size_t *buffer_size, int *h_errnop);
+ size_t *buffer_size, int *h_errnop)
+ attribute_hidden;
struct resolv_context;
struct hostent;
extern int __nss_hostname_digits_dots_context (struct resolv_context *,
@@ -221,6 +227,7 @@ libc_hidden_proto (__nss_hostname_digits_dots)
/* Prototypes for __nss_*_lookup2 functions. */
#define DEFINE_DATABASE(arg) \
+ service_user *__nss_##arg##_database attribute_hidden; \
int __nss_##arg##_lookup2 (service_user **, const char *, \
const char *, void **); \
libc_hidden_proto (__nss_##arg##_lookup2)
--
2.13.5