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author | Wladimir J. van der Laan <laanwj@protonmail.com> | 2021-03-16 13:07:52 +0100 |
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committer | Wladimir J. van der Laan <laanwj@protonmail.com> | 2021-03-16 13:11:59 +0100 |
commit | 1b6c463e033f861561d1a46ccf7eec069bbac09f (patch) | |
tree | a6175ed1a96ea54a5cfd275503ed6ffb65e9039a /src | |
parent | 77234793004a757426f67389d09bcee502033aa1 (diff) | |
parent | 7059e6d82275b44efc41675ee10760145b6c1073 (diff) | |
download | bitcoin-1b6c463e033f861561d1a46ccf7eec069bbac09f.tar.xz |
Merge #21407: i2p: limit the size of incoming messages
7059e6d82275b44efc41675ee10760145b6c1073 test: add a test to ensure RecvUntilTerminator() limit works (Vasil Dimov)
80a5a8ea2b7ad512c74c29df5b504e9be6cf23a0 i2p: limit the size of incoming messages (Vasil Dimov)
Pull request description:
Put a limit on the amount of data `Sock::RecvUntilTerminator()` can read
if no terminator is received.
In the case of I2P this avoids a runaway (or malicious) I2P proxy
sending us tons of data without a terminator before a timeout is
triggered.
ACKs for top commit:
laanwj:
Re-ACK 7059e6d82275b44efc41675ee10760145b6c1073
Tree-SHA512: 21f3f3468c765c726cdc877eae847cdb4dbe225d94c5bd1849bd752c9761fac881c554f16ea7a685ad40312159d554e126c481e21c5fd83a6d947060b920373d
Diffstat (limited to 'src')
-rw-r--r-- | src/i2p.cpp | 4 | ||||
-rw-r--r-- | src/i2p.h | 8 | ||||
-rw-r--r-- | src/test/sock_tests.cpp | 31 | ||||
-rw-r--r-- | src/util/sock.cpp | 10 | ||||
-rw-r--r-- | src/util/sock.h | 5 |
5 files changed, 53 insertions, 5 deletions
diff --git a/src/i2p.cpp b/src/i2p.cpp index 42270deaeb..d16c620d88 100644 --- a/src/i2p.cpp +++ b/src/i2p.cpp @@ -153,7 +153,7 @@ bool Session::Accept(Connection& conn) } const std::string& peer_dest = - conn.sock.RecvUntilTerminator('\n', MAX_WAIT_FOR_IO, *m_interrupt); + conn.sock.RecvUntilTerminator('\n', MAX_WAIT_FOR_IO, *m_interrupt, MAX_MSG_SIZE); conn.peer = CService(DestB64ToAddr(peer_dest), Params().GetDefaultPort()); @@ -252,7 +252,7 @@ Session::Reply Session::SendRequestAndGetReply(const Sock& sock, // signaled. static constexpr auto recv_timeout = 3min; - reply.full = sock.RecvUntilTerminator('\n', recv_timeout, *m_interrupt); + reply.full = sock.RecvUntilTerminator('\n', recv_timeout, *m_interrupt, MAX_MSG_SIZE); for (const auto& kv : spanparsing::Split(reply.full, ' ')) { const auto& pos = std::find(kv.begin(), kv.end(), '='); @@ -41,6 +41,14 @@ struct Connection { namespace sam { /** + * The maximum size of an incoming message from the I2P SAM proxy (in bytes). + * Used to avoid a runaway proxy from sending us an "unlimited" amount of data without a terminator. + * The longest known message is ~1400 bytes, so this is high enough not to be triggered during + * normal operation, yet low enough to avoid a malicious proxy from filling our memory. + */ +static constexpr size_t MAX_MSG_SIZE{65536}; + +/** * I2P SAM session. */ class Session diff --git a/src/test/sock_tests.cpp b/src/test/sock_tests.cpp index ed9780dfb5..400de875b7 100644 --- a/src/test/sock_tests.cpp +++ b/src/test/sock_tests.cpp @@ -4,11 +4,13 @@ #include <compat.h> #include <test/util/setup_common.h> +#include <threadinterrupt.h> #include <util/sock.h> #include <util/system.h> #include <boost/test/unit_test.hpp> +#include <cassert> #include <thread> using namespace std::chrono_literals; @@ -144,6 +146,35 @@ BOOST_AUTO_TEST_CASE(wait) waiter.join(); } +BOOST_AUTO_TEST_CASE(recv_until_terminator_limit) +{ + constexpr auto timeout = 1min; // High enough so that it is never hit. + CThreadInterrupt interrupt; + int s[2]; + CreateSocketPair(s); + + Sock sock_send(s[0]); + Sock sock_recv(s[1]); + + std::thread receiver([&sock_recv, &timeout, &interrupt]() { + constexpr size_t max_data{10}; + bool threw_as_expected{false}; + // BOOST_CHECK_EXCEPTION() writes to some variables shared with the main thread which + // creates a data race. So mimic it manually. + try { + sock_recv.RecvUntilTerminator('\n', timeout, interrupt, max_data); + } catch (const std::runtime_error& e) { + threw_as_expected = HasReason("too many bytes without a terminator")(e); + } + assert(threw_as_expected); + }); + + BOOST_REQUIRE_NO_THROW(sock_send.SendComplete("1234567", timeout, interrupt)); + BOOST_REQUIRE_NO_THROW(sock_send.SendComplete("89a\n", timeout, interrupt)); + + receiver.join(); +} + #endif /* WIN32 */ BOOST_AUTO_TEST_SUITE_END() diff --git a/src/util/sock.cpp b/src/util/sock.cpp index e13c52a16a..f9ecfef5d4 100644 --- a/src/util/sock.cpp +++ b/src/util/sock.cpp @@ -175,7 +175,8 @@ void Sock::SendComplete(const std::string& data, std::string Sock::RecvUntilTerminator(uint8_t terminator, std::chrono::milliseconds timeout, - CThreadInterrupt& interrupt) const + CThreadInterrupt& interrupt, + size_t max_data) const { const auto deadline = GetTime<std::chrono::milliseconds>() + timeout; std::string data; @@ -190,9 +191,14 @@ std::string Sock::RecvUntilTerminator(uint8_t terminator, // at a time is about 50 times slower. for (;;) { + if (data.size() >= max_data) { + throw std::runtime_error( + strprintf("Received too many bytes without a terminator (%u)", data.size())); + } + char buf[512]; - const ssize_t peek_ret{Recv(buf, sizeof(buf), MSG_PEEK)}; + const ssize_t peek_ret{Recv(buf, std::min(sizeof(buf), max_data - data.size()), MSG_PEEK)}; switch (peek_ret) { case -1: { diff --git a/src/util/sock.h b/src/util/sock.h index ecebb84205..4b0618dcff 100644 --- a/src/util/sock.h +++ b/src/util/sock.h @@ -135,13 +135,16 @@ public: * @param[in] terminator Character up to which to read from the socket. * @param[in] timeout Timeout for the entire operation. * @param[in] interrupt If this is signaled then the operation is canceled. + * @param[in] max_data The maximum amount of data (in bytes) to receive. If this many bytes + * are received and there is still no terminator, then this method will throw an exception. * @return The data that has been read, without the terminating character. * @throws std::runtime_error if the operation cannot be completed. In this case some bytes may * have been consumed from the socket. */ virtual std::string RecvUntilTerminator(uint8_t terminator, std::chrono::milliseconds timeout, - CThreadInterrupt& interrupt) const; + CThreadInterrupt& interrupt, + size_t max_data) const; /** * Check if still connected. |