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Avoid calling internal libc function through PLT or accessing data

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though GOT, by staticizing and hiding.  Add setter for
__error_selector to hide it as well.

Suggested and reviewed by:	jilles
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2015-01-05 01:06:54 +00:00
parent fd520b6e21
commit 1a744fefc2
5 changed files with 16 additions and 9 deletions
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4
lib/libc/include/libc_private.h
View File

@ -173,13 +173,13 @@ typedef pthread_func_t pthread_func_entry_t[2];
extern pthread_func_entry_t __thr_jtable[];
extern int *(*__error_selector)(void);
void __set_error_selector(int *(*arg)(void));
int _pthread_mutex_init_calloc_cb_stub(pthread_mutex_t *mutex,
void *(calloc_cb)(__size_t, __size_t));
typedef int (*interpos_func_t)(void);
interpos_func_t *__libc_interposing_slot(int interposno);
extern interpos_func_t __libc_interposing[];
extern interpos_func_t __libc_interposing[] __hidden;
enum {
INTERPOS_accept,

3
lib/libc/sys/Symbol.map
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@ -1045,8 +1045,7 @@ FBSDprivate_1.0 {
__sys_write;
_writev;
__sys_writev;
__error_unthreaded;
__error_selector;
__set_error_selector;
nlm_syscall;
gssd_syscall;
__libc_interposing_slot;

14
lib/libc/sys/__error.c
View File

@ -32,13 +32,21 @@ __FBSDID("$FreeBSD$");
extern int errno;
int *
static int *
__error_unthreaded(void)
{
return(&errno);
return (&errno);
}
int *(*__error_selector)(void) = __error_unthreaded;
static int *(*__error_selector)(void) = __error_unthreaded;
void
__set_error_selector(int *(*arg)(void))
{
__error_selector = arg;
}
int *
__error(void)

2
lib/libthr/thread/thr_private.h
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@ -914,7 +914,7 @@ void _thr_tsd_unload(struct dl_phdr_info *phdr_info) __hidden;
void _thr_sigact_unload(struct dl_phdr_info *phdr_info) __hidden;
void _thr_stack_fix_protection(struct pthread *thrd);
int *__error_threaded(void);
int *__error_threaded(void) __hidden;
void __thr_interpose_libc(void) __hidden;
pid_t __thr_fork(void);
int __thr_pause(void) __hidden;

2
lib/libthr/thread/thr_syscalls.c
View File

@ -692,7 +692,7 @@ void
__thr_interpose_libc(void)
{
__error_selector = __error_threaded;
__set_error_selector(__error_threaded);
#define SLOT(name) \
*(__libc_interposing_slot(INTERPOS_##name)) = \
(interpos_func_t)__thr_##name;