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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/processor/process_state.h"
#include "google_breakpad/processor/call_stack.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;
}
}
}
// 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;
// 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 MinidumpContext *context = exception->GetContext();
if (context == NULL) {
BPLOG(INFO) << "No exception context.";
return EXPLOITABILITY_ERR_PROCESSING;
}
// Getting instruction pointer based off architecture.
uint32_t architecture = context->GetContextCPU();
switch (architecture) {
case MD_CONTEXT_X86:
instruction_ptr = context->GetContextX86()->eip;
break;
case MD_CONTEXT_AMD64:
instruction_ptr = context->GetContextAMD64()->rip;
break;
default:
// TODO(liuandrew): Add support ARM and arm64 architectures.
BPLOG(INFO) << "Unsupported architecture.";
return EXPLOITABILITY_ERR_PROCESSING;
}
if (!this->InstructionPointerInCode(instruction_ptr)) {
return EXPLOITABILITY_HIGH;
}
return EXPLOITABILITY_NONE;
}
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);
}
} // namespace google_breakpad
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