nptl: Move legacy unwinding implementation into libc

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>

diff --git a/nptl/Versions b/nptl/Versions
index 60202b4969fc15d4bba508deae670ac1176fd6b1..2e5a964b11bad6e761ff22d85be47d3f94af4b8f 100644 (file)
--- a/nptl/Versions
+++ b/nptl/Versions
@@ -87,6 +87,8 @@ libc {
     __futex_abstimed_wait64;
     __futex_abstimed_wait_cancelable64;
     __libc_alloca_cutoff;
+    __libc_cleanup_pop_restore;
+    __libc_cleanup_push_defer;
     __libc_dl_error_tsd;
     __libc_pthread_init;
     __lll_clocklock_elision;

diff --git a/nptl/cleanup_defer_compat.c b/nptl/cleanup_defer_compat.c
index 49ef53ea60d051bc6601ac371557790db37867d7..1957318208136c6a71a80baab89cd5fa5e702103 100644 (file)
--- a/nptl/cleanup_defer_compat.c
+++ b/nptl/cleanup_defer_compat.c
@@ -17,41 +17,15 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include "pthreadP.h"
-
+#include <libc-lock.h>
 
 void
 _pthread_cleanup_push_defer (struct _pthread_cleanup_buffer *buffer,
                             void (*routine) (void *), void *arg)
 {
-  struct pthread *self = THREAD_SELF;
-
   buffer->__routine = routine;
   buffer->__arg = arg;
-  buffer->__prev = THREAD_GETMEM (self, cleanup);
-
-  int cancelhandling = THREAD_GETMEM (self, cancelhandling);
-
-  /* Disable asynchronous cancellation for now.  */
-  if (__glibc_unlikely (cancelhandling & CANCELTYPE_BITMASK))
-    while (1)
-      {
-       int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
-                                               cancelhandling
-                                               & ~CANCELTYPE_BITMASK,
-                                               cancelhandling);
-       if (__glibc_likely (curval == cancelhandling))
-         /* Successfully replaced the value.  */
-         break;
-
-       /* Prepare for the next round.  */
-       cancelhandling = curval;
-      }
-
-  buffer->__canceltype = (cancelhandling & CANCELTYPE_BITMASK
-                         ? PTHREAD_CANCEL_ASYNCHRONOUS
-                         : PTHREAD_CANCEL_DEFERRED);
-
-  THREAD_SETMEM (self, cleanup, buffer);
+  __libc_cleanup_push_defer (buffer);
 }
 strong_alias (_pthread_cleanup_push_defer, __pthread_cleanup_push_defer)
 
@@ -60,31 +34,7 @@ void
 _pthread_cleanup_pop_restore (struct _pthread_cleanup_buffer *buffer,
                              int execute)
 {
-  struct pthread *self = THREAD_SELF;
-
-  THREAD_SETMEM (self, cleanup, buffer->__prev);
-
-  int cancelhandling;
-  if (__builtin_expect (buffer->__canceltype != PTHREAD_CANCEL_DEFERRED, 0)
-      && ((cancelhandling = THREAD_GETMEM (self, cancelhandling))
-         & CANCELTYPE_BITMASK) == 0)
-    {
-      while (1)
-       {
-         int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
-                                                 cancelhandling
-                                                 | CANCELTYPE_BITMASK,
-                                                 cancelhandling);
-         if (__glibc_likely (curval == cancelhandling))
-           /* Successfully replaced the value.  */
-           break;
-
-         /* Prepare for the next round.  */
-         cancelhandling = curval;
-       }
-
-      CANCELLATION_P (self);
-    }
+  __libc_cleanup_pop_restore (buffer);
 
   /* If necessary call the cleanup routine after we removed the
      current cleanup block from the list.  */

diff --git a/nptl/libc-cleanup.c b/nptl/libc-cleanup.c
index 61f97eceda3df1c50762b5e6ad878dfd8d2f62c9..14ccfe92851ffc02c6bb1a592096905bfaa9e90e 100644 (file)
--- a/nptl/libc-cleanup.c
+++ b/nptl/libc-cleanup.c
@@ -17,11 +17,69 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include "pthreadP.h"
+#include <tls.h>
+#include <libc-lock.h>
 
+void
+__libc_cleanup_push_defer (struct _pthread_cleanup_buffer *buffer)
+{
+  struct pthread *self = THREAD_SELF;
+
+  buffer->__prev = THREAD_GETMEM (self, cleanup);
+
+  int cancelhandling = THREAD_GETMEM (self, cancelhandling);
+
+  /* Disable asynchronous cancellation for now.  */
+  if (__glibc_unlikely (cancelhandling & CANCELTYPE_BITMASK))
+    while (1)
+      {
+       int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
+                                               cancelhandling
+                                               & ~CANCELTYPE_BITMASK,
+                                               cancelhandling);
+       if (__glibc_likely (curval == cancelhandling))
+         /* Successfully replaced the value.  */
+         break;
+
+       /* Prepare for the next round.  */
+       cancelhandling = curval;
+      }
+
+  buffer->__canceltype = (cancelhandling & CANCELTYPE_BITMASK
+                         ? PTHREAD_CANCEL_ASYNCHRONOUS
+                         : PTHREAD_CANCEL_DEFERRED);
+
+  THREAD_SETMEM (self, cleanup, buffer);
+}
+libc_hidden_def (__libc_cleanup_push_defer)
 
 void
-__libc_cleanup_routine (struct __pthread_cleanup_frame *f)
+__libc_cleanup_pop_restore (struct _pthread_cleanup_buffer *buffer)
 {
-  if (f->__do_it)
-    f->__cancel_routine (f->__cancel_arg);
+  struct pthread *self = THREAD_SELF;
+
+  THREAD_SETMEM (self, cleanup, buffer->__prev);
+
+  int cancelhandling;
+  if (__builtin_expect (buffer->__canceltype != PTHREAD_CANCEL_DEFERRED, 0)
+      && ((cancelhandling = THREAD_GETMEM (self, cancelhandling))
+         & CANCELTYPE_BITMASK) == 0)
+    {
+      while (1)
+       {
+         int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
+                                                 cancelhandling
+                                                 | CANCELTYPE_BITMASK,
+                                                 cancelhandling);
+         if (__glibc_likely (curval == cancelhandling))
+           /* Successfully replaced the value.  */
+           break;
+
+         /* Prepare for the next round.  */
+         cancelhandling = curval;
+       }
+
+      CANCELLATION_P (self);
+    }
 }
+libc_hidden_def (__libc_cleanup_pop_restore)

diff --git a/nptl/nptl-init.c b/nptl/nptl-init.c
index 2c7e2222d491377e0b8716916d5734ba3ba33075..43e2564e59cbe3656306181154732d3e85e83bf3 100644 (file)
--- a/nptl/nptl-init.c
+++ b/nptl/nptl-init.c
@@ -95,8 +95,6 @@ static const struct pthread_functions pthread_functions =
     .ptr___pthread_key_create = __pthread_key_create,
     .ptr___pthread_getspecific = __pthread_getspecific,
     .ptr___pthread_setspecific = __pthread_setspecific,
-    .ptr__pthread_cleanup_push_defer = __pthread_cleanup_push_defer,
-    .ptr__pthread_cleanup_pop_restore = __pthread_cleanup_pop_restore,
     .ptr_nthreads = &__nptl_nthreads,
     .ptr___pthread_unwind = &__pthread_unwind,
     .ptr__nptl_deallocate_tsd = __nptl_deallocate_tsd,

diff --git a/sysdeps/nptl/libc-lock.h b/sysdeps/nptl/libc-lock.h
index dea96121b365e299dea3eeb3fe52ec539e2908d6..e8a5e68a129bd1b89385716ee9a421b431607a54 100644 (file)
--- a/sysdeps/nptl/libc-lock.h
+++ b/sysdeps/nptl/libc-lock.h
@@ -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

diff --git a/sysdeps/nptl/libc-lockP.h b/sysdeps/nptl/libc-lockP.h
index 63b605dee2f3365f952d65f7d6632437e29b817e..2c928b7a76ed4feda320e7c8fa35f2ddd1f8536d 100644 (file)
--- a/sysdeps/nptl/libc-lockP.h
+++ b/sysdeps/nptl/libc-lockP.h
@@ -251,32 +251,12 @@ _Static_assert (LLL_LOCK_INITIALIZER == 0, "LLL_LOCK_INITIALIZER != 0");
 /* Get once control variable.  */
 #define __libc_once_get(ONCE_CONTROL)  ((ONCE_CONTROL) != PTHREAD_ONCE_INIT)
 
-/* Note that for I/O cleanup handling we are using the old-style
-   cancel handling.  It does not have to be integrated with C++ snce
-   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 (struct _pthread_cleanup_buffer *buffer,
-                                  void (*routine) (void *), void *arg);
-extern void _pthread_cleanup_pop (struct _pthread_cleanup_buffer *buffer,
-                                 int execute);
-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);
-
-/* Sometimes we have to exit the block in the middle.  */
-#define __libc_cleanup_end(DOIT) \
-    if (_avail) {                                                            \
-      __libc_ptf_call_always (_pthread_cleanup_pop_restore, (&_buffer, DOIT));\
-    } else if (DOIT)                                                         \
-      _buffer.__routine (_buffer.__arg)
-
 /* __libc_cleanup_push and __libc_cleanup_pop depend on exception
    handling and stack unwinding.  */
 #ifdef __EXCEPTIONS
 
 /* Normal cleanup handling, based on C cleanup attribute.  */
-__extern_inline void
+static __always_inline void
 __libc_cleanup_routine (struct __pthread_cleanup_frame *f)
 {
   if (f->__do_it)
@@ -388,8 +368,6 @@ weak_extern (__pthread_once)
 weak_extern (__pthread_initialize)
 weak_extern (__pthread_atfork)
 weak_extern (__pthread_setcancelstate)
-weak_extern (_pthread_cleanup_push_defer)
-weak_extern (_pthread_cleanup_pop_restore)
 # else
 #  pragma weak __pthread_mutex_init
 #  pragma weak __pthread_mutex_destroy
@@ -412,8 +390,6 @@ weak_extern (_pthread_cleanup_pop_restore)
 #  pragma weak __pthread_initialize
 #  pragma weak __pthread_atfork
 #  pragma weak __pthread_setcancelstate
-#  pragma weak _pthread_cleanup_push_defer
-#  pragma weak _pthread_cleanup_pop_restore
 # endif
 #endif
 

diff --git a/sysdeps/nptl/pthread-functions.h b/sysdeps/nptl/pthread-functions.h
index 97a5c4893923d3f8dadba4a00f026602d59fcbe2..4268084b66b3c061e927fdf038d1a838936b1d00 100644 (file)
--- a/sysdeps/nptl/pthread-functions.h
+++ b/sysdeps/nptl/pthread-functions.h
@@ -57,10 +57,6 @@ struct pthread_functions
   int (*ptr___pthread_key_create) (pthread_key_t *, void (*) (void *));
   void *(*ptr___pthread_getspecific) (pthread_key_t);
   int (*ptr___pthread_setspecific) (pthread_key_t, const void *);
-  void (*ptr__pthread_cleanup_push_defer) (struct _pthread_cleanup_buffer *,
-                                          void (*) (void *), void *);
-  void (*ptr__pthread_cleanup_pop_restore) (struct _pthread_cleanup_buffer *,
-                                           int);
 #define HAVE_PTR_NTHREADS
   unsigned int *ptr_nthreads;
   void (*ptr___pthread_unwind) (__pthread_unwind_buf_t *)