Move dead submodules in-tree

Signed-off-by: swurl <swurl@swurl.xyz>

externals/breakpad/src/processor/exploitability_linux.cc

@@ -0,0 +1,320 @@
+// Copyright 2013 Google LLC
+//
+// 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 LLC 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
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>  // Must come first
+#endif
+
+#include "processor/exploitability_linux.h"
+
+#include <string.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"
+#ifdef __linux__
+#include "processor/disassembler_objdump.h"
+#endif
+#include "processor/logging.h"
+
+namespace {
+
+// Prefixes for memory mapping names.
+constexpr char kHeapPrefix[] = "[heap";
+constexpr char kStackPrefix[] =  "[stack";
+
+// This function in libc is called if the program was compiled with
+// -fstack-protector and a function's stack canary changes.
+constexpr 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.
+constexpr char kBoundsCheckFailureFunction[] = "__chk_fail";
+
+}  // namespace
+
+namespace google_breakpad {
+
+ExploitabilityLinux::ExploitabilityLinux(Minidump* dump,
+                                         ProcessState* process_state)
+    : Exploitability(dump, process_state),
+      enable_objdump_(false) { }
+
+ExploitabilityLinux::ExploitabilityLinux(Minidump* dump,
+                                         ProcessState* process_state,
+                                         bool enable_objdump)
+    : Exploitability(dump, process_state),
+      enable_objdump_(enable_objdump) { }
+
+
+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;
+  uint64_t stack_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)) {
+    BPLOG(INFO) << "Failed to retrieve instruction pointer.";
+    return EXPLOITABILITY_ERR_PROCESSING;
+  }
+
+  // Getting the stack pointer.
+  if (!context->GetStackPointer(&stack_ptr)) {
+    BPLOG(INFO) << "Failed to retrieve stack pointer.";
+    return EXPLOITABILITY_ERR_PROCESSING;
+  }
+
+  // Checking for the instruction pointer in a valid instruction region,
+  // a misplaced stack pointer, and an executable stack or heap.
+  if (!this->InstructionPointerInCode(instruction_ptr) ||
+       this->StackPointerOffStack(stack_ptr) ||
+       this->ExecutableStackOrHeap()) {
+    return EXPLOITABILITY_HIGH;
+  }
+
+  // Check for write to read only memory or invalid memory, shelling out
+  // to objdump is enabled.
+  if (enable_objdump_ && this->EndedOnIllegalWrite(instruction_ptr)) {
+    return EXPLOITABILITY_HIGH;
+  }
+
+  // There was no strong evidence suggesting exploitability, but the minidump
+  // does not appear totally benign either.
+  return EXPLOITABILITY_INTERESTING;
+}
+
+bool ExploitabilityLinux::EndedOnIllegalWrite(uint64_t instruction_ptr) {
+#ifndef __linux__
+  BPLOG(INFO) << "MinGW does not support fork and exec. Terminating method.";
+  return false;
+#else
+  // Get memory region containing instruction pointer.
+  MinidumpMemoryList* memory_list = dump_->GetMemoryList();
+  MinidumpMemoryRegion* memory_region =
+      memory_list ?
+      memory_list->GetMemoryRegionForAddress(instruction_ptr) : NULL;
+  if (!memory_region) {
+    BPLOG(INFO) << "No memory region around instruction pointer.";
+    return false;
+  }
+
+  // Get exception data to find architecture.
+  string architecture = "";
+  MinidumpException* exception = dump_->GetException();
+  // This should never evaluate to true, since this should not be reachable
+  // without checking for exception data earlier.
+  if (!exception) {
+    BPLOG(INFO) << "No exception data.";
+    return false;
+  }
+  const MDRawExceptionStream* raw_exception_stream = exception->exception();
+  const MinidumpContext* context = exception->GetContext();
+  // This should not evaluate to true, for the same reason mentioned above.
+  if (!raw_exception_stream || !context) {
+    BPLOG(INFO) << "No exception or architecture data.";
+    return false;
+  }
+
+  DisassemblerObjdump disassembler(context->GetContextCPU(), memory_region,
+                                   instruction_ptr);
+  if (!disassembler.IsValid()) {
+    BPLOG(INFO) << "Disassembling fault instruction failed.";
+    return false;
+  }
+
+  // Check if the operation is a write to memory.
+  // First, the instruction must one that can write to memory.
+  auto instruction = disassembler.operation();
+  if (!instruction.compare("mov") || !instruction.compare("inc") ||
+      !instruction.compare("dec") || !instruction.compare("and") ||
+      !instruction.compare("or") || !instruction.compare("xor") ||
+      !instruction.compare("not") || !instruction.compare("neg") ||
+      !instruction.compare("add") || !instruction.compare("sub") ||
+      !instruction.compare("shl") || !instruction.compare("shr")) {
+    uint64_t write_address = 0;
+
+    // Check that the destination is a memory address. CalculateDestAddress will
+    // return false if the destination is not a memory address.
+    if (!disassembler.CalculateDestAddress(*context, write_address)) {
+      return false;
+    }
+
+    // If the program crashed as a result of a write, the destination of
+    // the write must have been an address that did not permit writing.
+    // However, if the address is under 4k, due to program protections,
+    // the crash does not suggest exploitability for writes with such a
+    // low target address.
+    return write_address > 4096;
+  } else {
+    return false;
+  }
+#endif  // __linux__
+}
+
+bool ExploitabilityLinux::StackPointerOffStack(uint64_t stack_ptr) {
+  MinidumpLinuxMapsList* linux_maps_list = dump_->GetLinuxMapsList();
+  // Inconclusive if there are no mappings available.
+  if (!linux_maps_list) {
+    return false;
+  }
+  const MinidumpLinuxMaps* linux_maps =
+      linux_maps_list->GetLinuxMapsForAddress(stack_ptr);
+  // Checks if the stack pointer maps to a valid mapping and if the mapping
+  // is not the stack. If the mapping has no name, it is inconclusive whether
+  // it is off the stack.
+  return !linux_maps || (linux_maps->GetPathname().compare("") &&
+                         linux_maps->GetPathname().compare(
+                             0, strlen(kStackPrefix), kStackPrefix));
+}
+
+bool ExploitabilityLinux::ExecutableStackOrHeap() {
+  MinidumpLinuxMapsList* linux_maps_list = dump_->GetLinuxMapsList();
+  if (linux_maps_list) {
+    for (size_t i = 0; i < linux_maps_list->get_maps_count(); i++) {
+      const MinidumpLinuxMaps* linux_maps =
+          linux_maps_list->GetLinuxMapsAtIndex(i);
+      // Check for executable stack or heap for each mapping.
+      if (linux_maps && (!linux_maps->GetPathname().compare(
+                             0, strlen(kStackPrefix), kStackPrefix) ||
+                         !linux_maps->GetPathname().compare(
+                             0, strlen(kHeapPrefix), kHeapPrefix)) &&
+          linux_maps->IsExecutable()) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+bool ExploitabilityLinux::InstructionPointerInCode(uint64_t instruction_ptr) {
+  // Get Linux memory mapping from /proc/self/maps. Checking whether the
+  // region the instruction pointer is in has executable permission can tell
+  // whether it is in a valid code region. If there is no mapping for the
+  // instruction pointer, it is indicative that the instruction pointer is
+  // not within a module, which implies that it is outside a valid area.
+  MinidumpLinuxMapsList* linux_maps_list = dump_->GetLinuxMapsList();
+  const MinidumpLinuxMaps* linux_maps =
+      linux_maps_list ?
+      linux_maps_list->GetLinuxMapsForAddress(instruction_ptr) : NULL;
+  return linux_maps ? linux_maps->IsExecutable() : false;
+}
+
+bool ExploitabilityLinux::BenignCrashTrigger(
+    const MDRawExceptionStream* raw_exception_stream) {
+  // 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;
+    default:
+      return false;
+  }
+}
+
+}  // namespace google_breakpad