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// Copyright (c) 2013 Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// exploitability_linux.cc: Linux specific exploitability engine.
//
// Provides a guess at the exploitability of the crash for the Linux
// platform given a minidump and process_state.
//
// Author: Matthew Riley
#include "processor/exploitability_linux.h"
#include "google_breakpad/common/minidump_exception_linux.h"
#include "google_breakpad/processor/call_stack.h"
#include "google_breakpad/processor/process_state.h"
#include "google_breakpad/processor/stack_frame.h"
#include "processor/logging.h"
namespace {
// This function in libc is called if the program was compiled with
// -fstack-protector and a function's stack canary changes.
const char kStackCheckFailureFunction[] = "__stack_chk_fail";
// This function in libc is called if the program was compiled with
// -D_FORTIFY_SOURCE=2, a function like strcpy() is called, and the runtime
// can determine that the call would overflow the target buffer.
const char kBoundsCheckFailureFunction[] = "__chk_fail";
} // namespace
namespace google_breakpad {
ExploitabilityLinux::ExploitabilityLinux(Minidump *dump,
ProcessState *process_state)
: Exploitability(dump, process_state) { }
ExploitabilityRating ExploitabilityLinux::CheckPlatformExploitability() {
// Check the crashing thread for functions suggesting a buffer overflow or
// stack smash.
if (process_state_->requesting_thread() != -1) {
CallStack* crashing_thread =
process_state_->threads()->at(process_state_->requesting_thread());
const vector<StackFrame*>& crashing_thread_frames =
*crashing_thread->frames();
for (size_t i = 0; i < crashing_thread_frames.size(); ++i) {
if (crashing_thread_frames[i]->function_name ==
kStackCheckFailureFunction) {
return EXPLOITABILITY_HIGH;
}
if (crashing_thread_frames[i]->function_name ==
kBoundsCheckFailureFunction) {
return EXPLOITABILITY_HIGH;
}
}
}
// Getting exception data. (It should exist for all minidumps.)
MinidumpException *exception = dump_->GetException();
if (exception == NULL) {
BPLOG(INFO) << "No exception record.";
return EXPLOITABILITY_ERR_PROCESSING;
}
const MDRawExceptionStream *raw_exception_stream = exception->exception();
if (raw_exception_stream == NULL) {
BPLOG(INFO) << "No raw exception stream.";
return EXPLOITABILITY_ERR_PROCESSING;
}
// Checking for benign exceptions that caused the crash.
if (this->BenignCrashTrigger(raw_exception_stream)) {
return EXPLOITABILITY_NONE;
}
// Check if the instruction pointer is in a valid instruction region
// by finding if it maps to an executable part of memory.
uint64_t instruction_ptr = 0;
const MinidumpContext *context = exception->GetContext();
if (context == NULL) {
BPLOG(INFO) << "No exception context.";
return EXPLOITABILITY_ERR_PROCESSING;
}
// Getting the instruction pointer.
if (!context->GetInstructionPointer(&instruction_ptr)) {
return EXPLOITABILITY_ERR_PROCESSING;
}
// Checking for the instruction pointer in a valid instruction region.
if (!this->InstructionPointerInCode(instruction_ptr)) {
return EXPLOITABILITY_HIGH;
}
return EXPLOITABILITY_INTERESTING;
}
bool ExploitabilityLinux::InstructionPointerInCode(uint64_t instruction_ptr) {
// Here we get memory mapping. Most minidumps will not contain a memory
// mapping, so we will commonly resort to checking modules.
MinidumpMemoryInfoList *mem_info_list = dump_->GetMemoryInfoList();
const MinidumpMemoryInfo *mem_info =
mem_info_list ?
mem_info_list->GetMemoryInfoForAddress(instruction_ptr) : NULL;
// Checking if the memory mapping at the instruction pointer is executable.
// If there is no memory mapping, we will use the modules as reference.
if (mem_info != NULL) {
return mem_info->IsExecutable();
}
// If the memory mapping retrieval fails, we will check the modules
// to see if the instruction pointer is inside a module.
// TODO(liuandrew): Check if the instruction pointer lies in an executable
// region within the module.
MinidumpModuleList *minidump_module_list = dump_->GetModuleList();
return !minidump_module_list ||
minidump_module_list->GetModuleForAddress(instruction_ptr);
}
bool ExploitabilityLinux::BenignCrashTrigger(const MDRawExceptionStream
*raw_exception_stream) {
// Here we check the cause of crash.
// If the exception of the crash is a benign exception,
// it is probably not exploitable.
switch (raw_exception_stream->exception_record.exception_code) {
case MD_EXCEPTION_CODE_LIN_SIGHUP:
case MD_EXCEPTION_CODE_LIN_SIGINT:
case MD_EXCEPTION_CODE_LIN_SIGQUIT:
case MD_EXCEPTION_CODE_LIN_SIGTRAP:
case MD_EXCEPTION_CODE_LIN_SIGABRT:
case MD_EXCEPTION_CODE_LIN_SIGFPE:
case MD_EXCEPTION_CODE_LIN_SIGKILL:
case MD_EXCEPTION_CODE_LIN_SIGUSR1:
case MD_EXCEPTION_CODE_LIN_SIGUSR2:
case MD_EXCEPTION_CODE_LIN_SIGPIPE:
case MD_EXCEPTION_CODE_LIN_SIGALRM:
case MD_EXCEPTION_CODE_LIN_SIGTERM:
case MD_EXCEPTION_CODE_LIN_SIGCHLD:
case MD_EXCEPTION_CODE_LIN_SIGCONT:
case MD_EXCEPTION_CODE_LIN_SIGSTOP:
case MD_EXCEPTION_CODE_LIN_SIGTSTP:
case MD_EXCEPTION_CODE_LIN_SIGTTIN:
case MD_EXCEPTION_CODE_LIN_SIGTTOU:
case MD_EXCEPTION_CODE_LIN_SIGURG:
case MD_EXCEPTION_CODE_LIN_SIGXCPU:
case MD_EXCEPTION_CODE_LIN_SIGXFSZ:
case MD_EXCEPTION_CODE_LIN_SIGVTALRM:
case MD_EXCEPTION_CODE_LIN_SIGPROF:
case MD_EXCEPTION_CODE_LIN_SIGWINCH:
case MD_EXCEPTION_CODE_LIN_SIGIO:
case MD_EXCEPTION_CODE_LIN_SIGPWR:
case MD_EXCEPTION_CODE_LIN_SIGSYS:
case MD_EXCEPTION_CODE_LIN_DUMP_REQUESTED:
return true;
break;
default:
return false;
break;
}
}
} // namespace google_breakpad
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