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Merge #17095: util: Filter control characters out of log messages

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d7820a1250070f3640246ae497e049bee0b3516f util: Filter control characters out of log messages (Wladimir J. van der Laan)

Pull request description:

  Belts and suspenders: make sure outgoing log messages don't contain potentially suspicious characters, such as terminal control codes.

  This escapes control characters except newline ('\n') in C syntax. It escapes instead of removes them to still allow for troubleshooting issues where they accidentally end up in strings (it is a debug log, after all).

  (more checks could be added such as UTF-8 validity and unicode code-point range checking—this is substantially more involved and would need to keep track of state between characters and even `LogPrint` calls as they could end up split up—but escape codes seem to be the most common attack vector for terminals.)

ACKs for top commit:
  practicalswift:
    ACK d7820a1250070f3640246ae497e049bee0b3516f - tested and works as expected :)

Tree-SHA512: 0806265addebdcec1062a6def3e903555e62ba5e93967ce9ee6943d16462a222b3f41135a5bff0a76966ae9e7ed75f211d7785bceda788ae0b0654bf3fd891bf
This commit is contained in:
Wladimir J. van der Laan 2019-10-16 16:04:16 +02:00
commit c34b88620d
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GPG Key ID: 1E4AED62986CD25D
2 changed files with 41 additions and 1 deletions
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24
src/logging.cpp
View File

@ -224,10 +224,32 @@ std::string BCLog::Logger::LogTimestampStr(const std::string& str)
return strStamped;
}
namespace BCLog {
/** Belts and suspenders: make sure outgoing log messages don't contain
* potentially suspicious characters, such as terminal control codes.
*
* This escapes control characters except newline ('\n') in C syntax.
* It escapes instead of removes them to still allow for troubleshooting
* issues where they accidentally end up in strings.
*/
std::string LogEscapeMessage(const std::string& str) {
std::string ret;
for (char ch_in : str) {
uint8_t ch = (uint8_t)ch_in;
if ((ch >= 32 || ch == '\n') && ch != '\x7f') {
ret += ch_in;
} else {
ret += strprintf("\\x%02x", ch);
}
}
return ret;
}
}
void BCLog::Logger::LogPrintStr(const std::string& str)
{
std::lock_guard<std::mutex> scoped_lock(m_cs);
std::string str_prefixed = str;
std::string str_prefixed = LogEscapeMessage(str);
if (m_log_threadnames && m_started_new_line) {
str_prefixed.insert(0, "[" + util::ThreadGetInternalName() + "] ");

18
src/test/util_tests.cpp
View File

@ -26,6 +26,11 @@
#include <boost/test/unit_test.hpp>
/* defined in logging.cpp */
namespace BCLog {
std::string LogEscapeMessage(const std::string& str);
}
BOOST_FIXTURE_TEST_SUITE(util_tests, BasicTestingSetup)
BOOST_AUTO_TEST_CASE(util_criticalsection)
@ -1696,4 +1701,17 @@ BOOST_AUTO_TEST_CASE(test_spanparsing)
BOOST_CHECK_EQUAL(SpanToStr(results[3]), "");
}
BOOST_AUTO_TEST_CASE(test_LogEscapeMessage)
{
// ASCII and UTF-8 must pass through unaltered.
BOOST_CHECK_EQUAL(BCLog::LogEscapeMessage("Valid log message貓"), "Valid log message貓");
// Newlines must pass through unaltered.
BOOST_CHECK_EQUAL(BCLog::LogEscapeMessage("Message\n with newlines\n"), "Message\n with newlines\n");
// Other control characters are escaped in C syntax.
BOOST_CHECK_EQUAL(BCLog::LogEscapeMessage("\x01\x7f Corrupted log message\x0d"), R"(\x01\x7f Corrupted log message\x0d)");
// Embedded NULL characters are escaped too.
const std::string NUL("O\x00O", 3);
BOOST_CHECK_EQUAL(BCLog::LogEscapeMessage(NUL), R"(O\x00O)");
}
BOOST_AUTO_TEST_SUITE_END()