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nptl: Move legacy unwinding implementation into libc

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It is still used internally.  Since unwinding is now available
unconditionally, avoid indirect calls through function pointers loaded
from the stack by inlining the non-cancellation cleanup code.  This
avoids a regression in security hardening.

The out-of-line  __libc_cleanup_routine implementation is no longer
needed because the inline definition is now static __always_inline.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Florian Weimer
2021-04-21 19:49:50 +02:00
parent 5715c29e91
commit f79f206581
7 changed files with 98 additions and 117 deletions
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59
sysdeps/nptl/libc-lock.h
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@@ -143,39 +143,40 @@ typedef struct __libc_lock_recursive_opaque__ __libc_lock_recursive_t;
__libc_maybe_call (__pthread_mutex_unlock, (&(NAME).mutex), 0)
#endif
/* Note that for I/O cleanup handling we are using the old-style
cancel handling. It does not have to be integrated with C++ since
no C++ code is called in the middle. The old-style handling is
faster and the support is not going away. */
extern void _pthread_cleanup_push_defer (struct _pthread_cleanup_buffer *buffer,
void (*routine) (void *), void *arg);
extern void _pthread_cleanup_pop_restore (struct _pthread_cleanup_buffer *buffer,
int execute);
/* Put the unwind buffer BUFFER on the per-thread callback stack. The
caller must fill BUFFER->__routine and BUFFER->__arg before calling
this function. */
void __libc_cleanup_push_defer (struct _pthread_cleanup_buffer *buffer);
libc_hidden_proto (__libc_cleanup_push_defer)
/* Remove BUFFER from the unwind callback stack. The caller must invoke
the callback if desired. */
void __libc_cleanup_pop_restore (struct _pthread_cleanup_buffer *buffer);
libc_hidden_proto (__libc_cleanup_pop_restore)
/* Start critical region with cleanup. */
#define __libc_cleanup_region_start(DOIT, FCT, ARG) \
{ struct _pthread_cleanup_buffer _buffer; \
int _avail; \
if (DOIT) { \
_avail = PTFAVAIL (_pthread_cleanup_push_defer); \
if (_avail) { \
__libc_ptf_call_always (_pthread_cleanup_push_defer, (&_buffer, FCT, \
ARG)); \
} else { \
_buffer.__routine = (FCT); \
_buffer.__arg = (ARG); \
} \
} else { \
_avail = 0; \
}
#define __libc_cleanup_region_start(DOIT, FCT, ARG) \
{ bool _cleanup_start_doit; \
struct _pthread_cleanup_buffer _buffer; \
/* Non-addressable copy of FCT, so that we avoid indirect calls on \
the non-unwinding path. */ \
void (*_cleanup_routine) (void *) = (FCT); \
_buffer.__arg = (ARG); \
if (DOIT) \
{ \
_cleanup_start_doit = true; \
_buffer.__routine = _cleanup_routine; \
__libc_cleanup_push_defer (&_buffer); \
} \
else \
_cleanup_start_doit = false;
/* End critical region with cleanup. */
#define __libc_cleanup_region_end(DOIT) \
if (_avail) { \
__libc_ptf_call_always (_pthread_cleanup_pop_restore, (&_buffer, DOIT));\
} else if (DOIT) \
_buffer.__routine (_buffer.__arg); \
}
#define __libc_cleanup_region_end(DOIT) \
if (_cleanup_start_doit) \
__libc_cleanup_pop_restore (&_buffer); \
if (DOIT) \
_cleanup_routine (_buffer.__arg); \
} /* matches __libc_cleanup_region_start */
/* Hide the definitions which are only supposed to be used inside libc in