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afl-gcc-common.h
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/* GCC plugin common infrastructure for AFL++ instrumentation passes.
Copyright 2014-2019 Free Software Foundation, Inc
Copyright 2015, 2016 Google Inc. All rights reserved.
Copyright 2019-2023 AdaCore
Written by Alexandre Oliva <[email protected]>, based on the AFL++
GCC plugin.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "../include/config.h"
#include "../include/debug.h"
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#ifdef likely
#undef likely
#endif
#ifdef unlikely
#undef unlikely
#endif
#include <list>
#include <string>
#include <fstream>
#include <algorithm>
#include <fnmatch.h>
#include <gcc-plugin.h>
#include <plugin-version.h>
#include <toplev.h>
#include <tree-pass.h>
#include <context.h>
#include <tree.h>
#include <gimplify.h>
#include <basic-block.h>
#include <tree-ssa-alias.h>
#include <gimple-expr.h>
#include <gimple.h>
#include <gimple-iterator.h>
#include <stringpool.h>
#include <gimple-ssa.h>
#if (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) >= \
60200 /* >= version 6.2.0 */
#include <tree-vrp.h>
#endif
#include <tree-ssanames.h>
#include <tree-phinodes.h>
#include <ssa-iterators.h>
#include <intl.h>
namespace {
struct afl_base_pass : gimple_opt_pass {
afl_base_pass(bool quiet, bool debug, struct pass_data const &pd)
: gimple_opt_pass(pd, g), be_quiet(quiet), debug(debug) {
initInstrumentList();
}
/* Are we outputting to a non-terminal, or running with AFL_QUIET
set? */
const bool be_quiet;
/* Are we running with AFL_DEBUG set? */
const bool debug;
#define report_fatal_error(msg) BADF(msg)
std::list<std::string> allowListFiles;
std::list<std::string> allowListFunctions;
std::list<std::string> denyListFiles;
std::list<std::string> denyListFunctions;
/* Note: this ignore check is also called in isInInstrumentList() */
bool isIgnoreFunction(function *F) {
// Starting from "LLVMFuzzer" these are functions used in libfuzzer based
// fuzzing campaign installations, e.g. oss-fuzz
static constexpr const char *ignoreList[] = {
"asan.",
"llvm.",
"sancov.",
"__ubsan_",
"ign.",
"__afl_",
"_fini",
"__libc_csu",
"__asan",
"__msan",
"__cmplog",
"__sancov",
"msan.",
"LLVMFuzzerM",
"LLVMFuzzerC",
"LLVMFuzzerI",
"__decide_deferred",
"maybe_duplicate_stderr",
"discard_output",
"close_stdout",
"dup_and_close_stderr",
"maybe_close_fd_mask",
"ExecuteFilesOnyByOne"
};
const char *name = IDENTIFIER_POINTER(DECL_NAME(F->decl));
int len = IDENTIFIER_LENGTH(DECL_NAME(F->decl));
for (auto const &ignoreListFunc : ignoreList) {
if (strncmp(name, ignoreListFunc, len) == 0) { return true; }
}
return false;
}
void initInstrumentList() {
char *allowlist = getenv("AFL_GCC_ALLOWLIST");
if (!allowlist) allowlist = getenv("AFL_GCC_INSTRUMENT_FILE");
if (!allowlist) allowlist = getenv("AFL_GCC_WHITELIST");
if (!allowlist) allowlist = getenv("AFL_LLVM_ALLOWLIST");
if (!allowlist) allowlist = getenv("AFL_LLVM_INSTRUMENT_FILE");
if (!allowlist) allowlist = getenv("AFL_LLVM_WHITELIST");
char *denylist = getenv("AFL_GCC_DENYLIST");
if (!denylist) denylist = getenv("AFL_GCC_BLOCKLIST");
if (!denylist) denylist = getenv("AFL_LLVM_DENYLIST");
if (!denylist) denylist = getenv("AFL_LLVM_BLOCKLIST");
if (allowlist && denylist)
FATAL(
"You can only specify either AFL_GCC_ALLOWLIST or AFL_GCC_DENYLIST "
"but not both!");
if (allowlist) {
std::string line;
std::ifstream fileStream;
fileStream.open(allowlist);
if (!fileStream) report_fatal_error("Unable to open AFL_GCC_ALLOWLIST");
getline(fileStream, line);
while (fileStream) {
int is_file = -1;
std::size_t npos;
std::string original_line = line;
line.erase(std::remove_if(line.begin(), line.end(), ::isspace),
line.end());
// remove # and following
if ((npos = line.find("#")) != std::string::npos)
line = line.substr(0, npos);
if (line.compare(0, 4, "fun:") == 0) {
is_file = 0;
line = line.substr(4);
} else if (line.compare(0, 9, "function:") == 0) {
is_file = 0;
line = line.substr(9);
} else if (line.compare(0, 4, "src:") == 0) {
is_file = 1;
line = line.substr(4);
} else if (line.compare(0, 7, "source:") == 0) {
is_file = 1;
line = line.substr(7);
}
if (line.find(":") != std::string::npos) {
FATAL("invalid line in AFL_GCC_ALLOWLIST: %s", original_line.c_str());
}
if (line.length() > 0) {
// if the entry contains / or . it must be a file
if (is_file == -1)
if (line.find("/") != std::string::npos ||
line.find(".") != std::string::npos)
is_file = 1;
// otherwise it is a function
if (is_file == 1)
allowListFiles.push_back(line);
else
allowListFunctions.push_back(line);
}
getline(fileStream, line);
}
if (debug)
DEBUGF("loaded allowlist with %zu file and %zu function entries\n",
allowListFiles.size(), allowListFunctions.size());
}
if (denylist) {
std::string line;
std::ifstream fileStream;
fileStream.open(denylist);
if (!fileStream) report_fatal_error("Unable to open AFL_GCC_DENYLIST");
getline(fileStream, line);
while (fileStream) {
int is_file = -1;
std::size_t npos;
std::string original_line = line;
line.erase(std::remove_if(line.begin(), line.end(), ::isspace),
line.end());
// remove # and following
if ((npos = line.find("#")) != std::string::npos)
line = line.substr(0, npos);
if (line.compare(0, 4, "fun:") == 0) {
is_file = 0;
line = line.substr(4);
} else if (line.compare(0, 9, "function:") == 0) {
is_file = 0;
line = line.substr(9);
} else if (line.compare(0, 4, "src:") == 0) {
is_file = 1;
line = line.substr(4);
} else if (line.compare(0, 7, "source:") == 0) {
is_file = 1;
line = line.substr(7);
}
if (line.find(":") != std::string::npos) {
FATAL("invalid line in AFL_GCC_DENYLIST: %s", original_line.c_str());
}
if (line.length() > 0) {
// if the entry contains / or . it must be a file
if (is_file == -1)
if (line.find("/") != std::string::npos ||
line.find(".") != std::string::npos)
is_file = 1;
// otherwise it is a function
if (is_file == 1)
denyListFiles.push_back(line);
else
denyListFunctions.push_back(line);
}
getline(fileStream, line);
}
if (debug)
DEBUGF("loaded denylist with %zu file and %zu function entries\n",
denyListFiles.size(), denyListFunctions.size());
}
}
/* Returns the source file name attached to the function declaration F. If
there is no source location information, returns an empty string. */
std::string getSourceName(function *F) {
return DECL_SOURCE_FILE(F->decl) ? DECL_SOURCE_FILE(F->decl) : "";
}
bool isInInstrumentList(function *F) {
bool return_default = true;
// is this a function with code? If it is external we don't instrument it
// anyway and it can't be in the instrument file list. Or if it is it is
// ignored.
if (isIgnoreFunction(F)) return false;
if (!denyListFiles.empty() || !denyListFunctions.empty()) {
if (!denyListFunctions.empty()) {
std::string instFunction = IDENTIFIER_POINTER(DECL_NAME(F->decl));
for (std::list<std::string>::iterator it = denyListFunctions.begin();
it != denyListFunctions.end(); ++it) {
/* We don't check for filename equality here because
* filenames might actually be full paths. Instead we
* check that the actual filename ends in the filename
* specified in the list. We also allow UNIX-style pattern
* matching */
if (instFunction.length() >= it->length()) {
if (fnmatch(("*" + *it).c_str(), instFunction.c_str(), 0) == 0) {
if (debug)
DEBUGF(
"Function %s is in the deny function list, not "
"instrumenting ... \n",
instFunction.c_str());
return false;
}
}
}
}
if (!denyListFiles.empty()) {
std::string source_file = getSourceName(F);
if (!source_file.empty()) {
for (std::list<std::string>::iterator it = denyListFiles.begin();
it != denyListFiles.end(); ++it) {
/* We don't check for filename equality here because
* filenames might actually be full paths. Instead we
* check that the actual filename ends in the filename
* specified in the list. We also allow UNIX-style pattern
* matching */
if (source_file.length() >= it->length()) {
if (fnmatch(("*" + *it).c_str(), source_file.c_str(), 0) == 0) {
return false;
}
}
}
} else {
// we could not find out the location. in this case we say it is not
// in the instrument file list
if (!be_quiet)
WARNF(
"No debug information found for function %s, will be "
"instrumented (recompile with -g -O[1-3]).",
IDENTIFIER_POINTER(DECL_NAME(F->decl)));
}
}
}
// if we do not have a instrument file list return true
if (!allowListFiles.empty() || !allowListFunctions.empty()) {
return_default = false;
if (!allowListFunctions.empty()) {
std::string instFunction = IDENTIFIER_POINTER(DECL_NAME(F->decl));
for (std::list<std::string>::iterator it = allowListFunctions.begin();
it != allowListFunctions.end(); ++it) {
/* We don't check for filename equality here because
* filenames might actually be full paths. Instead we
* check that the actual filename ends in the filename
* specified in the list. We also allow UNIX-style pattern
* matching */
if (instFunction.length() >= it->length()) {
if (fnmatch(("*" + *it).c_str(), instFunction.c_str(), 0) == 0) {
if (debug)
DEBUGF(
"Function %s is in the allow function list, instrumenting "
"... \n",
instFunction.c_str());
return true;
}
}
}
}
if (!allowListFiles.empty()) {
std::string source_file = getSourceName(F);
if (!source_file.empty()) {
for (std::list<std::string>::iterator it = allowListFiles.begin();
it != allowListFiles.end(); ++it) {
/* We don't check for filename equality here because
* filenames might actually be full paths. Instead we
* check that the actual filename ends in the filename
* specified in the list. We also allow UNIX-style pattern
* matching */
if (source_file.length() >= it->length()) {
if (fnmatch(("*" + *it).c_str(), source_file.c_str(), 0) == 0) {
if (debug)
DEBUGF(
"Function %s is in the allowlist (%s), instrumenting ... "
"\n",
IDENTIFIER_POINTER(DECL_NAME(F->decl)),
source_file.c_str());
return true;
}
}
}
} else {
// we could not find out the location. In this case we say it is not
// in the instrument file list
if (!be_quiet)
WARNF(
"No debug information found for function %s, will not be "
"instrumented (recompile with -g -O[1-3]).",
IDENTIFIER_POINTER(DECL_NAME(F->decl)));
return false;
}
}
}
return return_default;
}
};
} // namespace
// compatibility for older gcc versions
#if (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) >= \
60200 /* >= version 6.2.0 */
#define gimple gimple *
#else
#define gimple gimple
#endif