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ImHex/plugins/yara_rules/source/content/yara_rule.cpp

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#include <content/yara_rule.hpp>
#include <wolv/literals.hpp>
#include <wolv/utils/guards.hpp>
#include <wolv/utils/string.hpp>
#include <wolv/io/file.hpp>
// <yara/types.h>'s RE type has a zero-sized array, which is not allowed in ISO C++.
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpedantic"
#include <yara.h>
#pragma GCC diagnostic pop
namespace hex::plugin::yara {
using namespace wolv::literals;
struct ResultContext {
YaraRule *rule;
std::vector<YaraRule::Rule> matchedRules;
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std::vector<std::string> consoleMessages;
std::string includeBuffer;
};
void YaraRule::init() {
yr_initialize();
}
void YaraRule::cleanup() {
yr_finalize();
}
YaraRule::YaraRule(const std::string &content) : m_content(content) { }
YaraRule::YaraRule(const std::fs::path &path) : m_filePath(path) {
wolv::io::File file(path, wolv::io::File::Mode::Read);
if (!file.isValid())
return;
m_content = file.readString();
}
static int scanFunction(YR_SCAN_CONTEXT *context, int message, void *data, void *userData) {
auto &resultContext = *static_cast<ResultContext *>(userData);
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switch (message) {
case CALLBACK_MSG_RULE_MATCHING: {
const auto *rule = static_cast<const YR_RULE *>(data);
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if (rule->strings != nullptr) {
YR_STRING *string;
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yr_rule_strings_foreach(rule, string) {
YaraRule::Rule newRule;
newRule.identifier = rule->identifier;
YR_MATCH *match;
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yr_string_matches_foreach(context, string, match) {
newRule.matches.push_back({ string->identifier, Region { u64(match->offset), size_t(match->match_length) }, false });
}
YR_META *meta;
yr_rule_metas_foreach(rule, meta) {
newRule.metadata[meta->identifier] = meta->string;
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}
const char *tag;
yr_rule_tags_foreach(rule, tag) {
newRule.tags.emplace_back(tag);
}
resultContext.matchedRules.emplace_back(std::move(newRule));
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}
} else {
YaraRule::Rule newRule;
newRule.identifier = rule->identifier;
newRule.matches.push_back({ "", Region::Invalid(), true });
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}
break;
}
case CALLBACK_MSG_CONSOLE_LOG: {
resultContext.consoleMessages.emplace_back(static_cast<const char *>(data));
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break;
}
default:
break;
}
return resultContext.rule->isInterrupted() ? CALLBACK_ABORT : CALLBACK_CONTINUE;
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}
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wolv::util::Expected<YaraRule::Result, YaraRule::Error> YaraRule::match(prv::Provider *provider, Region region) {
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YR_COMPILER *compiler = nullptr;
yr_compiler_create(&compiler);
ON_SCOPE_EXIT {
yr_compiler_destroy(compiler);
};
m_interrupted = false;
ResultContext resultContext = {};
resultContext.rule = this;
yr_compiler_set_include_callback(
compiler,
[](const char *includeName, const char *, const char *, void *userData) -> const char * {
auto context = static_cast<ResultContext *>(userData);
wolv::io::File file(context->rule->m_filePath.parent_path() / includeName, wolv::io::File::Mode::Read);
if (!file.isValid())
return nullptr;
context->includeBuffer = file.readString();
return context->includeBuffer.c_str();
},
[](const char *ptr, void *userData) {
hex::unused(ptr, userData);
},
&resultContext
);
if (yr_compiler_add_string(compiler, m_content.c_str(), nullptr) != ERROR_SUCCESS) {
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std::string errorMessage(0xFFFF, '\x00');
yr_compiler_get_error_message(compiler, errorMessage.data(), errorMessage.size());
return wolv::util::Unexpected(Error { Error::Type::CompileError, errorMessage.c_str() });
}
YR_RULES *yaraRules;
yr_compiler_get_rules(compiler, &yaraRules);
ON_SCOPE_EXIT { yr_rules_destroy(yaraRules); };
YR_MEMORY_BLOCK_ITERATOR iterator;
struct ScanContext {
prv::Provider *provider;
Region region;
std::vector<u8> buffer;
YR_MEMORY_BLOCK currBlock = {};
};
ScanContext context;
context.provider = provider;
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context.region = region;
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context.currBlock.base = 0;
context.currBlock.fetch_data = [](YR_MEMORY_BLOCK *block) -> const u8 * {
auto &context = *static_cast<ScanContext *>(block->context);
context.buffer.resize(context.currBlock.size);
if (context.buffer.empty())
return nullptr;
block->size = context.currBlock.size;
context.provider->read(context.provider->getBaseAddress() + context.currBlock.base, context.buffer.data(), context.buffer.size());
return context.buffer.data();
};
iterator.file_size = [](YR_MEMORY_BLOCK_ITERATOR *iterator) -> u64 {
auto &context = *static_cast<ScanContext *>(iterator->context);
return context.region.size;
};
iterator.context = &context;
iterator.first = [](YR_MEMORY_BLOCK_ITERATOR *iterator) -> YR_MEMORY_BLOCK *{
auto &context = *static_cast<ScanContext *>(iterator->context);
context.currBlock.base = context.region.address;
context.currBlock.size = 0;
context.buffer.clear();
iterator->last_error = ERROR_SUCCESS;
return iterator->next(iterator);
};
iterator.next = [](YR_MEMORY_BLOCK_ITERATOR *iterator) -> YR_MEMORY_BLOCK * {
auto &context = *static_cast<ScanContext *>(iterator->context);
u64 address = context.currBlock.base + context.currBlock.size;
iterator->last_error = ERROR_SUCCESS;
context.currBlock.base = address;
context.currBlock.size = std::min<size_t>(context.region.size - (address - context.region.address), 10_MiB);
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context.currBlock.context = &context;
if (context.currBlock.size == 0) return nullptr;
return &context.currBlock;
};
if (yr_rules_scan_mem_blocks(yaraRules, &iterator, 0, scanFunction, &resultContext, 0) != ERROR_SUCCESS) {
std::string errorMessage(0xFFFF, '\x00');
yr_compiler_get_error_message(compiler, errorMessage.data(), errorMessage.size());
return wolv::util::Unexpected(Error { Error::Type::RuntimeError, errorMessage.c_str() });
}
if (m_interrupted)
return wolv::util::Unexpected(Error { Error::Type::Interrupted, "" });
return Result { resultContext.matchedRules, resultContext.consoleMessages };
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}
void YaraRule::interrupt() {
m_interrupted = true;
}
bool YaraRule::isInterrupted() const {
return m_interrupted;
}
}