ext-cryptopp/trap.h
Jeffrey Walton 399a1546de Add CRYPTOPP_ASSERT (Issue 277, CVE-2016-7420)
trap.h and CRYPTOPP_ASSERT has existed for over a year in Master. We deferred on the cut-over waiting for a minor version bump (5.7). We have to use it now due to CVE-2016-7420
2016-09-16 11:27:15 -04:00

178 lines
8.5 KiB
C++

// trap.h - written and placed in public domain by Jeffrey Walton.
// Copyright assigned to Crypto++ project
//! \file trap.h
//! \brief Debugging and diagnostic assertions
//! \details <tt>CRYPTOPP_ASSERT</tt> is the library's debugging and diagnostic assertion. <tt>CRYPTOPP_ASSERT</tt>
//! is enabled by <tt>CRYPTOPP_DEBUG</tt>, <tt>DEBUG</tt> or <tt>_DEBUG</tt>.
//! \details <tt>CRYPTOPP_ASSERT</tt> raises a <tt>SIGTRAP</tt> (Unix) or calls <tt>DebugBreak()</tt> (Windows).
//! <tt>CRYPTOPP_ASSERT</tt> is only in effect when the user requests a debug configuration. Unlike Posix assert,
//! <tt>NDEBUG</tt> (or failure to define it) does not affect the library.
//! The traditional Posix define <tt>NDEBUG</tt> has no effect on <tt>CRYPTOPP_DEBUG</tt> or DebugTrapHandler.
//! \since Crypto++ 5.6.5
//! \sa DebugTrapHandler, <A HREF="http://github.com/weidai11/cryptopp/issues/277">Issue 277</A>,
//! <A HREF="http://seclists.org/oss-sec/2016/q3/520">CVE-2016-7420</A>
#ifndef CRYPTOPP_TRAP_H
#define CRYPTOPP_TRAP_H
#include "config.h"
#if CRYPTOPP_DEBUG
# include <iostream>
# include <sstream>
# if defined(CRYPTOPP_WIN32_AVAILABLE)
# define WIN32_LEAN_AND_MEAN
# include <Windows.h>
# elif defined(CRYPTOPP_BSD_AVAILABLE) || defined(CRYPTOPP_UNIX_AVAILABLE)
# include <signal.h>
# endif
#endif // CRYPTOPP_DEBUG
// ************** run-time assertion ***************
#if defined(CRYPTOPP_DOXYGEN_PROCESSING)
//! \brief Debugging and diagnostic assertion
//! \details <tt>CRYPTOPP_ASSERT</tt> is the library's debugging and diagnostic assertion. <tt>CRYPTOPP_ASSERT</tt>
//! is enabled by the preprocessor macros <tt>CRYPTOPP_DEBUG</tt>, <tt>DEBUG</tt> or <tt>_DEBUG</tt>.
//! \details <tt>CRYPTOPP_ASSERT</tt> raises a <tt>SIGTRAP</tt> (Unix) or calls <tt>DebugBreak()</tt> (Windows).
//! <tt>CRYPTOPP_ASSERT</tt> is only in effect when the user explictly requests a debug configuration.
//! \details If you want to ensure <tt>CRYPTOPP_ASSERT</tt> is inert, then <em>do not</em> define
//! <tt>CRYPTOPP_DEBUG</tt>, <tt>DEBUG</tt> or <tt>_DEBUG</tt>. Avoiding the defines means <tt>CRYPTOPP_ASSERT</tt>
//! is processed into <tt>((void)(exp))</tt>.
//! \details The traditional Posix define <tt>NDEBUG</tt> has no effect on <tt>CRYPTOPP_DEBUG</tt>, <tt>CRYPTOPP_ASSERT</tt>
//! or DebugTrapHandler.
//! \details An example of using \ref CRYPTOPP_ASSERT "CRYPTOPP_ASSERT" and DebugTrapHandler is shown below. The library's
//! test program, <tt>cryptest.exe</tt> (from test.cpp), exercises the structure:
//! <pre>
//! #if CRYPTOPP_DEBUG && (defined(CRYPTOPP_BSD_AVAILABLE) || defined(CRYPTOPP_UNIX_AVAILABLE))
//! static const DebugTrapHandler g_dummyHandler;
//! #endif
//!
//! int main(int argc, char* argv[])
//! {
//! CRYPTOPP_ASSERT(argv != nullptr);
//! ...
//! }
//! </pre>
//! \since Crypto++ 5.6.5
//! \sa DebugTrapHandler, SignalHandler, <A HREF="http://github.com/weidai11/cryptopp/issues/277">Issue 277</A>,
//! <A HREF="http://seclists.org/oss-sec/2016/q3/520">CVE-2016-7420</A>
# define CRYPTOPP_ASSERT(exp) { ... }
#endif
#if CRYPTOPP_DEBUG && (defined(CRYPTOPP_BSD_AVAILABLE) || defined(CRYPTOPP_UNIX_AVAILABLE))
# define CRYPTOPP_ASSERT(exp) { \
if (!(exp)) { \
std::ostringstream oss; \
oss << "Assertion failed: " << (char*)(__FILE__) << "(" \
<< (int)(__LINE__) << "): " << (char*)(__func__) \
<< std::endl; \
std::cerr << oss.str(); \
raise(SIGTRAP); \
} \
}
#elif CRYPTOPP_DEBUG && defined(CRYPTOPP_WIN32_AVAILABLE)
# define CRYPTOPP_ASSERT(exp) { \
if (!(exp)) { \
std::ostringstream oss; \
oss << "Assertion failed: " << (char*)(__FILE__) << "(" \
<< (int)(__LINE__) << "): " << (char*)(__FUNCTION__) \
<< std::endl; \
std::cerr << oss.str(); \
DebugBreak(); \
} \
}
#endif // DEBUG and Unix or Windows
// Remove CRYPTOPP_ASSERT in non-debug builds.
// Can't use CRYPTOPP_UNUSED due to circular dependency
#ifndef CRYPTOPP_ASSERT
# define CRYPTOPP_ASSERT(exp) ((void)(exp))
#endif
NAMESPACE_BEGIN(CryptoPP)
// ************** SIGTRAP handler ***************
#if (CRYPTOPP_DEBUG && (defined(CRYPTOPP_BSD_AVAILABLE) || defined(CRYPTOPP_UNIX_AVAILABLE))) || defined(CRYPTOPP_DOXYGEN_PROCESSING)
//! \brief Default SIGTRAP handler
//! \details DebugTrapHandler() can be used by a program to install an empty SIGTRAP handler. If present,
//! the handler ensures there is a signal handler in place for <tt>SIGTRAP</tt> raised by
//! <tt>CRYPTOPP_ASSERT</tt>. If <tt>CRYPTOPP_ASSERT</tt> raises <tt>SIGTRAP</tt> <em>without</em>
//! a handler, then one of two things can occur. First, the OS might allow the program
//! to continue. Second, the OS might terminate the program. OS X allows the program to continue, while
//! some Linuxes terminate the program.
//! \details If DebugTrapHandler detects another handler in place, then it will not install a handler. This
//! ensures a debugger can gain control of the <tt>SIGTRAP</tt> signal without contention. It also allows multiple
//! DebugTrapHandler to be created without contentious or unusual behavior. Though muliple DebugTrapHandler can be
//! created, a program should only create one, if needed.
//! \details A DebugTrapHandler is subject to C++ static initialization [dis]order. If you need to install a handler
//! and it must be installed early, then reference the code associated with <tt>CRYPTOPP_INIT_PRIORITY</tt> in
//! cryptlib.cpp and cpu.cpp.
//! \details If you want to ensure <tt>CRYPTOPP_ASSERT</tt> is inert, then <em>do not</em> define
//! <tt>CRYPTOPP_DEBUG</tt>, <tt>DEBUG</tt> or <tt>_DEBUG</tt>. Avoiding the defines means <tt>CRYPTOPP_ASSERT</tt>
//! is processed into <tt>((void)(exp))</tt>.
//! \details The traditional Posix define <tt>NDEBUG</tt> has no effect on <tt>CRYPTOPP_DEBUG</tt>, <tt>CRYPTOPP_ASSERT</tt>
//! or DebugTrapHandler.
//! \details An example of using \ref CRYPTOPP_ASSERT "CRYPTOPP_ASSERT" and DebugTrapHandler is shown below. The library's
//! test program, <tt>cryptest.exe</tt> (from test.cpp), exercises the structure:
//! <pre>
//! #if CRYPTOPP_DEBUG && (defined(CRYPTOPP_BSD_AVAILABLE) || defined(CRYPTOPP_UNIX_AVAILABLE))
//! static const DebugTrapHandler g_dummyHandler;
//! #endif
//!
//! int main(int argc, char* argv[])
//! {
//! CRYPTOPP_ASSERT(argv != nullptr);
//! ...
//! }
//! </pre>
//! \since Crypto++ 5.6.5
//! \sa \ref CRYPTOPP_ASSERT "CRYPTOPP_ASSERT", SignalHandler, <A HREF="http://github.com/weidai11/cryptopp/issues/277">Issue 277</A>,
//! <A HREF="http://seclists.org/oss-sec/2016/q3/520">CVE-2016-7420</A>
struct DebugTrapHandler
{
DebugTrapHandler()
{
// http://pubs.opengroup.org/onlinepubs/007908799/xsh/sigaction.html
struct sigaction old_handler, new_handler;
memset(&old_handler, 0x00, sizeof(old_handler));
memset(&new_handler, 0x00, sizeof(new_handler));
do
{
int ret = 0;
ret = sigaction (SIGTRAP, 0, &old_handler);
if (ret != 0) break; // Failed
// Don't step on another's handler
if (old_handler.sa_handler != 0) break;
// Set up the structure to specify the NULL action.
new_handler.sa_handler = &DebugTrapHandler::NullHandler;
new_handler.sa_flags = 0;
ret = sigemptyset (&new_handler.sa_mask);
if (ret != 0) break; // Failed
// Install it
ret = sigaction (SIGTRAP, &new_handler, 0);
if (ret != 0) break; // Failed
} while(0);
}
static void NullHandler(int /*unused*/) { }
private:
DebugTrapHandler(const DebugTrapHandler &);
void operator=(const DebugTrapHandler &);
};
#endif // DebugTrapHandler
NAMESPACE_END
#endif // CRYPTOPP_TRAP_H