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https://github.com/mozilla/gecko-dev.git
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e5e885ae31
# ignore-this-changeset --HG-- extra : amend_source : 7221c8d15a765df71171099468e7c7faa648f37c extra : histedit_source : a0cce6015636202bff09e35a13f72e03257a7695
342 lines
10 KiB
C++
342 lines
10 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "PoisonIOInterposer.h"
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#include "mach_override.h"
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#include "mozilla/ArrayUtils.h"
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#include "mozilla/Assertions.h"
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#include "mozilla/DebugOnly.h"
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#include "mozilla/IOInterposer.h"
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#include "mozilla/Mutex.h"
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#include "mozilla/ProcessedStack.h"
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#include "mozilla/Telemetry.h"
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#include "mozilla/UniquePtrExtensions.h"
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#include "nsPrintfCString.h"
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#include "mozilla/StackWalk.h"
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#include "nsTraceRefcnt.h"
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#include "plstr.h"
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#include "prio.h"
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#include <algorithm>
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#include <vector>
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#include <sys/param.h>
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#include <sys/stat.h>
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#include <sys/socket.h>
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#include <sys/uio.h>
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#include <aio.h>
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#include <dlfcn.h>
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#include <fcntl.h>
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#include <unistd.h>
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#ifdef MOZ_REPLACE_MALLOC
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# include "replace_malloc_bridge.h"
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#endif
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namespace {
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using namespace mozilla;
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// Bit tracking if poisoned writes are enabled
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static bool sIsEnabled = false;
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// Check if writes are dirty before reporting IO
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static bool sOnlyReportDirtyWrites = false;
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// Routines for write validation
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bool IsValidWrite(int aFd, const void* aWbuf, size_t aCount);
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bool IsIPCWrite(int aFd, const struct stat& aBuf);
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/******************************** IO AutoTimer ********************************/
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/**
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* RAII class for timing the duration of an I/O call and reporting the result
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* to the IOInterposeObserver API.
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*/
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class MacIOAutoObservation : public IOInterposeObserver::Observation {
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public:
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MacIOAutoObservation(IOInterposeObserver::Operation aOp, int aFd)
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: IOInterposeObserver::Observation(aOp, sReference,
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sIsEnabled && !IsDebugFile(aFd)),
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mFd(aFd),
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mHasQueriedFilename(false) {}
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MacIOAutoObservation(IOInterposeObserver::Operation aOp, int aFd,
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const void* aBuf, size_t aCount)
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: IOInterposeObserver::Observation(
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aOp, sReference,
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sIsEnabled && !IsDebugFile(aFd) && IsValidWrite(aFd, aBuf, aCount)),
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mFd(aFd),
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mHasQueriedFilename(false) {}
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// Custom implementation of IOInterposeObserver::Observation::Filename
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void Filename(nsAString& aFilename) override;
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~MacIOAutoObservation() { Report(); }
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private:
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int mFd;
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bool mHasQueriedFilename;
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nsString mFilename;
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static const char* sReference;
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};
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const char* MacIOAutoObservation::sReference = "PoisonIOInterposer";
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// Get filename for this observation
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void MacIOAutoObservation::Filename(nsAString& aFilename) {
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// If mHasQueriedFilename is true, then we already have it
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if (mHasQueriedFilename) {
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aFilename = mFilename;
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return;
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}
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char filename[MAXPATHLEN];
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if (fcntl(mFd, F_GETPATH, filename) != -1) {
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mFilename = NS_ConvertUTF8toUTF16(filename);
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} else {
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mFilename.Truncate();
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}
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mHasQueriedFilename = true;
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aFilename = mFilename;
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}
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/****************************** Write Validation ******************************/
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// We want to detect "actual" writes, not IPC. Some IPC mechanisms are
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// implemented with file descriptors, so filter them out.
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bool IsIPCWrite(int aFd, const struct stat& aBuf) {
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if ((aBuf.st_mode & S_IFMT) == S_IFIFO) {
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return true;
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}
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if ((aBuf.st_mode & S_IFMT) != S_IFSOCK) {
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return false;
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}
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sockaddr_storage address;
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socklen_t len = sizeof(address);
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if (getsockname(aFd, (sockaddr*)&address, &len) != 0) {
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return true; // Ignore the aFd if we can't find what it is.
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}
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return address.ss_family == AF_UNIX;
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}
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// We want to report actual disk IO not things that don't move bits on the disk
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bool IsValidWrite(int aFd, const void* aWbuf, size_t aCount) {
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// Ignore writes of zero bytes, Firefox does some during shutdown.
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if (aCount == 0) {
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return false;
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}
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{
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struct stat buf;
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int rv = fstat(aFd, &buf);
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if (rv != 0) {
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return true;
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}
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if (IsIPCWrite(aFd, buf)) {
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return false;
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}
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}
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// For writev we pass a nullptr aWbuf. We should only get here from
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// dbm, and it uses write, so assert that we have aWbuf.
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if (!aWbuf) {
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return true;
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}
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// Break, here if we're allowed to report non-dirty writes
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if (!sOnlyReportDirtyWrites) {
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return true;
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}
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// As a really bad hack, accept writes that don't change the on disk
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// content. This is needed because dbm doesn't keep track of dirty bits
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// and can end up writing the same data to disk twice. Once when the
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// user (nss) asks it to sync and once when closing the database.
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auto wbuf2 = MakeUniqueFallible<char[]>(aCount);
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if (!wbuf2) {
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return true;
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}
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off_t pos = lseek(aFd, 0, SEEK_CUR);
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if (pos == -1) {
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return true;
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}
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ssize_t r = read(aFd, wbuf2.get(), aCount);
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if (r < 0 || (size_t)r != aCount) {
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return true;
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}
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int cmp = memcmp(aWbuf, wbuf2.get(), aCount);
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if (cmp != 0) {
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return true;
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}
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off_t pos2 = lseek(aFd, pos, SEEK_SET);
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if (pos2 != pos) {
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return true;
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}
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// Otherwise this is not a valid write
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return false;
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}
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/*************************** Function Interception ***************************/
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/** Structure for declaration of function override */
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struct FuncData {
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const char* Name; // Name of the function for the ones we use dlsym
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const void* Wrapper; // The function that we will replace 'Function' with
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void* Function; // The function that will be replaced with 'Wrapper'
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void* Buffer; // Will point to the jump buffer that lets us call
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// 'Function' after it has been replaced.
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};
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// Wrap aio_write. We have not seen it before, so just assert/report it.
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typedef ssize_t (*aio_write_t)(struct aiocb* aAioCbp);
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ssize_t wrap_aio_write(struct aiocb* aAioCbp);
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FuncData aio_write_data = {0, (void*)wrap_aio_write, (void*)aio_write};
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ssize_t wrap_aio_write(struct aiocb* aAioCbp) {
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MacIOAutoObservation timer(IOInterposeObserver::OpWrite, aAioCbp->aio_fildes);
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aio_write_t old_write = (aio_write_t)aio_write_data.Buffer;
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return old_write(aAioCbp);
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}
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// Wrap pwrite-like functions.
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// We have not seen them before, so just assert/report it.
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typedef ssize_t (*pwrite_t)(int aFd, const void* buf, size_t aNumBytes,
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off_t aOffset);
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template <FuncData& foo>
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ssize_t wrap_pwrite_temp(int aFd, const void* aBuf, size_t aNumBytes,
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off_t aOffset) {
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MacIOAutoObservation timer(IOInterposeObserver::OpWrite, aFd);
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pwrite_t old_write = (pwrite_t)foo.Buffer;
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return old_write(aFd, aBuf, aNumBytes, aOffset);
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}
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// Define a FuncData for a pwrite-like functions.
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#define DEFINE_PWRITE_DATA(X, NAME) \
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FuncData X##_data = {NAME, (void*)wrap_pwrite_temp<X##_data>};
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// This exists everywhere.
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DEFINE_PWRITE_DATA(pwrite, "pwrite")
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// These exist on 32 bit OS X
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DEFINE_PWRITE_DATA(pwrite_NOCANCEL_UNIX2003, "pwrite$NOCANCEL$UNIX2003");
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DEFINE_PWRITE_DATA(pwrite_UNIX2003, "pwrite$UNIX2003");
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// This exists on 64 bit OS X
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DEFINE_PWRITE_DATA(pwrite_NOCANCEL, "pwrite$NOCANCEL");
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typedef ssize_t (*writev_t)(int aFd, const struct iovec* aIov, int aIovCount);
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template <FuncData& foo>
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ssize_t wrap_writev_temp(int aFd, const struct iovec* aIov, int aIovCount) {
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MacIOAutoObservation timer(IOInterposeObserver::OpWrite, aFd, nullptr,
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aIovCount);
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writev_t old_write = (writev_t)foo.Buffer;
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return old_write(aFd, aIov, aIovCount);
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}
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// Define a FuncData for a writev-like functions.
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#define DEFINE_WRITEV_DATA(X, NAME) \
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FuncData X##_data = {NAME, (void*)wrap_writev_temp<X##_data>};
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// This exists everywhere.
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DEFINE_WRITEV_DATA(writev, "writev");
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// These exist on 32 bit OS X
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DEFINE_WRITEV_DATA(writev_NOCANCEL_UNIX2003, "writev$NOCANCEL$UNIX2003");
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DEFINE_WRITEV_DATA(writev_UNIX2003, "writev$UNIX2003");
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// This exists on 64 bit OS X
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DEFINE_WRITEV_DATA(writev_NOCANCEL, "writev$NOCANCEL");
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typedef ssize_t (*write_t)(int aFd, const void* aBuf, size_t aCount);
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template <FuncData& foo>
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ssize_t wrap_write_temp(int aFd, const void* aBuf, size_t aCount) {
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MacIOAutoObservation timer(IOInterposeObserver::OpWrite, aFd, aBuf, aCount);
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write_t old_write = (write_t)foo.Buffer;
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return old_write(aFd, aBuf, aCount);
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}
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// Define a FuncData for a write-like functions.
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#define DEFINE_WRITE_DATA(X, NAME) \
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FuncData X##_data = {NAME, (void*)wrap_write_temp<X##_data>};
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// This exists everywhere.
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DEFINE_WRITE_DATA(write, "write");
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// These exist on 32 bit OS X
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DEFINE_WRITE_DATA(write_NOCANCEL_UNIX2003, "write$NOCANCEL$UNIX2003");
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DEFINE_WRITE_DATA(write_UNIX2003, "write$UNIX2003");
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// This exists on 64 bit OS X
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DEFINE_WRITE_DATA(write_NOCANCEL, "write$NOCANCEL");
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FuncData* Functions[] = {&aio_write_data,
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&pwrite_data, &pwrite_NOCANCEL_UNIX2003_data,
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&pwrite_UNIX2003_data, &pwrite_NOCANCEL_data,
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&write_data, &write_NOCANCEL_UNIX2003_data,
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&write_UNIX2003_data, &write_NOCANCEL_data,
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&writev_data, &writev_NOCANCEL_UNIX2003_data,
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&writev_UNIX2003_data, &writev_NOCANCEL_data};
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const int NumFunctions = ArrayLength(Functions);
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} // namespace
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/******************************** IO Poisoning ********************************/
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namespace mozilla {
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void InitPoisonIOInterposer() {
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// Enable reporting from poisoned write methods
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sIsEnabled = true;
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// Make sure we only poison writes once!
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static bool WritesArePoisoned = false;
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if (WritesArePoisoned) {
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return;
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}
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WritesArePoisoned = true;
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// stdout and stderr are OK.
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MozillaRegisterDebugFD(1);
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MozillaRegisterDebugFD(2);
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#ifdef MOZ_REPLACE_MALLOC
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// The contract with InitDebugFd is that the given registry can be used
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// at any moment, so the instance needs to persist longer than the scope
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// of this functions.
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static DebugFdRegistry registry;
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ReplaceMalloc::InitDebugFd(registry);
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#endif
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for (int i = 0; i < NumFunctions; ++i) {
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FuncData* d = Functions[i];
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if (!d->Function) {
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d->Function = dlsym(RTLD_DEFAULT, d->Name);
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}
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if (!d->Function) {
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continue;
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}
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DebugOnly<mach_error_t> t =
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mach_override_ptr(d->Function, d->Wrapper, &d->Buffer);
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MOZ_ASSERT(t == err_none);
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}
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}
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void OnlyReportDirtyWrites() { sOnlyReportDirtyWrites = true; }
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void ClearPoisonIOInterposer() {
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// Not sure how or if we can unpoison the functions. Would be nice, but no
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// worries we won't need to do this anyway.
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sIsEnabled = false;
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}
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} // namespace mozilla
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