So it turns out that libcrypto on i386 platforms, unconditionaly compiles this

little gem called OPENSSL_indirect_call(), supposedly to be ``handy under
Win32''.

In my view, this is a free-win ROP entry point. Why try and return to libc
when you can return to libcrypto with an easy to use interface?

Better not give that much attack surface, and remove this undocumented
entry point.

ok beck@ tedu@

diff --git a/lib/libcrypto/x86cpuid.pl b/lib/libcrypto/x86cpuid.pl
index c7a57a3..169036d 100644 (file)
--- a/lib/libcrypto/x86cpuid.pl
+++ b/lib/libcrypto/x86cpuid.pl
@@ -257,45 +257,6 @@ for (@ARGV) { $sse2=1 if (/-DOPENSSL_IA32_SSE2/); }
        &ret    ();
 &function_end_B("OPENSSL_atomic_add");
 
-# This function can become handy under Win32 in situations when
-# we don't know which calling convention, __stdcall or __cdecl(*),
-# indirect callee is using. In C it can be deployed as
-#
-#ifdef OPENSSL_CPUID_OBJ
-#      type OPENSSL_indirect_call(void *f,...);
-#      ...
-#      OPENSSL_indirect_call(func,[up to $max arguments]);
-#endif
-#
-# (*)  it's designed to work even for __fastcall if number of
-#      arguments is 1 or 2!
-&function_begin_B("OPENSSL_indirect_call");
-       {
-       my ($max,$i)=(7,);      # $max has to be chosen as 4*n-1
-                               # in order to preserve eventual
-                               # stack alignment
-       &push   ("ebp");
-       &mov    ("ebp","esp");
-       &sub    ("esp",$max*4);
-       &mov    ("ecx",&DWP(12,"ebp"));
-       &mov    (&DWP(0,"esp"),"ecx");
-       &mov    ("edx",&DWP(16,"ebp"));
-       &mov    (&DWP(4,"esp"),"edx");
-       for($i=2;$i<$max;$i++)
-               {
-               # Some copies will be redundant/bogus...
-               &mov    ("eax",&DWP(12+$i*4,"ebp"));
-               &mov    (&DWP(0+$i*4,"esp"),"eax");
-               }
-       &call_ptr       (&DWP(8,"ebp"));# make the call...
-       &mov    ("esp","ebp");  # ... and just restore the stack pointer
-                               # without paying attention to what we called,
-                               # (__cdecl *func) or (__stdcall *one).
-       &pop    ("ebp");
-       &ret    ();
-       }
-&function_end_B("OPENSSL_indirect_call");
-
 &function_begin_B("OPENSSL_ia32_rdrand");
        &mov    ("ecx",8);
 &set_label("loop");

diff --git a/lib/libssl/src/crypto/x86cpuid.pl b/lib/libssl/src/crypto/x86cpuid.pl
index c7a57a3..169036d 100644 (file)
--- a/lib/libssl/src/crypto/x86cpuid.pl
+++ b/lib/libssl/src/crypto/x86cpuid.pl
@@ -257,45 +257,6 @@ for (@ARGV) { $sse2=1 if (/-DOPENSSL_IA32_SSE2/); }
        &ret    ();
 &function_end_B("OPENSSL_atomic_add");
 
-# This function can become handy under Win32 in situations when
-# we don't know which calling convention, __stdcall or __cdecl(*),
-# indirect callee is using. In C it can be deployed as
-#
-#ifdef OPENSSL_CPUID_OBJ
-#      type OPENSSL_indirect_call(void *f,...);
-#      ...
-#      OPENSSL_indirect_call(func,[up to $max arguments]);
-#endif
-#
-# (*)  it's designed to work even for __fastcall if number of
-#      arguments is 1 or 2!
-&function_begin_B("OPENSSL_indirect_call");
-       {
-       my ($max,$i)=(7,);      # $max has to be chosen as 4*n-1
-                               # in order to preserve eventual
-                               # stack alignment
-       &push   ("ebp");
-       &mov    ("ebp","esp");
-       &sub    ("esp",$max*4);
-       &mov    ("ecx",&DWP(12,"ebp"));
-       &mov    (&DWP(0,"esp"),"ecx");
-       &mov    ("edx",&DWP(16,"ebp"));
-       &mov    (&DWP(4,"esp"),"edx");
-       for($i=2;$i<$max;$i++)
-               {
-               # Some copies will be redundant/bogus...
-               &mov    ("eax",&DWP(12+$i*4,"ebp"));
-               &mov    (&DWP(0+$i*4,"esp"),"eax");
-               }
-       &call_ptr       (&DWP(8,"ebp"));# make the call...
-       &mov    ("esp","ebp");  # ... and just restore the stack pointer
-                               # without paying attention to what we called,
-                               # (__cdecl *func) or (__stdcall *one).
-       &pop    ("ebp");
-       &ret    ();
-       }
-&function_end_B("OPENSSL_indirect_call");
-
 &function_begin_B("OPENSSL_ia32_rdrand");
        &mov    ("ecx",8);
 &set_label("loop");