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Fix thread-safety bug in SSL_get_peer_cert_chain.

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https://boringssl-review.googlesource.com/12704 pushed it just too far
to the edge. Once we have an established SSL_SESSION, any modifications
need to either be locked or done ahead of time. Do it ahead of time.
session->is_server gives a suitable place to check and X509s are
ref-counted so this should be cheap.

Add a regression test via TSan. Confirmed that TSan indeed catches this.

Change-Id: I30ce7b757d3a44465b318af3c98961ff3667483e
Reviewed-on: https://boringssl-review.googlesource.com/c/33606
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: Adam Langley <agl@google.com>
This commit is contained in:
David Benjamin 2018-12-13 12:20:54 -06:00 committed by CQ bot account: commit-bot@chromium.org
parent 200fe6786b
commit 4cce955d14
3 changed files with 98 additions and 45 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
ssl/ssl_asn1.cc
View File

@ -697,11 +697,6 @@ UniquePtr<SSL_SESSION> SSL_SESSION_parse(CBS *cbs,
}
}
if (!x509_method->session_cache_objects(ret.get())) {
OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
return nullptr;
}
CBS age_add;
int age_add_present;
if (!CBS_get_optional_asn1_octet_string(&session, &age_add, &age_add_present,
@ -737,6 +732,11 @@ UniquePtr<SSL_SESSION> SSL_SESSION_parse(CBS *cbs,
return nullptr;
}
if (!x509_method->session_cache_objects(ret.get())) {
OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
return nullptr;
}
return ret;
}

59
ssl/ssl_test.cc
View File

@ -4521,6 +4521,65 @@ TEST(SSLTest, GetCertificateThreads) {
EXPECT_EQ(cert2, cert2_thread);
EXPECT_EQ(0, X509_cmp(cert.get(), cert2));
}
// Functions which access properties on the negotiated session are thread-safe
// where needed. Prior to TLS 1.3, clients resuming sessions and servers
// performing stateful resumption will share an underlying SSL_SESSION object,
// potentially across threads.
TEST_P(SSLVersionTest, SessionPropertiesThreads) {
if (version() == TLS1_3_VERSION) {
// Our TLS 1.3 implementation does not support stateful resumption.
ASSERT_FALSE(CreateClientSession(client_ctx_.get(), server_ctx_.get()));
return;
}
SSL_CTX_set_options(server_ctx_.get(), SSL_OP_NO_TICKET);
SSL_CTX_set_session_cache_mode(client_ctx_.get(), SSL_SESS_CACHE_BOTH);
SSL_CTX_set_session_cache_mode(server_ctx_.get(), SSL_SESS_CACHE_BOTH);
ASSERT_TRUE(UseCertAndKey(client_ctx_.get()));
ASSERT_TRUE(UseCertAndKey(server_ctx_.get()));
// Configure mutual authentication, so we have more session state.
SSL_CTX_set_custom_verify(
client_ctx_.get(), SSL_VERIFY_PEER,
[](SSL *ssl, uint8_t *out_alert) { return ssl_verify_ok; });
SSL_CTX_set_custom_verify(
server_ctx_.get(), SSL_VERIFY_PEER,
[](SSL *ssl, uint8_t *out_alert) { return ssl_verify_ok; });
// Establish a client session to test with.
bssl::UniquePtr<SSL_SESSION> session =
CreateClientSession(client_ctx_.get(), server_ctx_.get());
ASSERT_TRUE(session);
// Resume with it twice.
UniquePtr<SSL> ssls[4];
ClientConfig config;
config.session = session.get();
ASSERT_TRUE(ConnectClientAndServer(&ssls[0], &ssls[1], client_ctx_.get(),
server_ctx_.get(), config));
ASSERT_TRUE(ConnectClientAndServer(&ssls[2], &ssls[3], client_ctx_.get(),
server_ctx_.get(), config));
// Read properties in parallel.
auto read_properties = [](const SSL *ssl) {
EXPECT_TRUE(SSL_get_peer_cert_chain(ssl));
bssl::UniquePtr<X509> peer(SSL_get_peer_certificate(ssl));
EXPECT_TRUE(peer);
EXPECT_TRUE(SSL_get_current_cipher(ssl));
EXPECT_TRUE(SSL_get_curve_id(ssl));
};
std::vector<std::thread> threads;
for (const auto &ssl_ptr : ssls) {
const SSL *ssl = ssl_ptr.get();
threads.emplace_back([=] { read_properties(ssl); });
}
for (auto &thread : threads) {
thread.join();
}
}
#endif
constexpr size_t kNumQUICLevels = 4;

74
ssl/ssl_x509.cc
View File

@ -281,16 +281,25 @@ static void ssl_crypto_x509_cert_dup(CERT *new_cert, const CERT *cert) {
}
static int ssl_crypto_x509_session_cache_objects(SSL_SESSION *sess) {
bssl::UniquePtr<STACK_OF(X509)> chain;
bssl::UniquePtr<STACK_OF(X509)> chain, chain_without_leaf;
if (sk_CRYPTO_BUFFER_num(sess->certs.get()) > 0) {
chain.reset(sk_X509_new_null());
if (!chain) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
return 0;
}
if (sess->is_server) {
// chain_without_leaf is only needed for server sessions. See
// |SSL_get_peer_cert_chain|.
chain_without_leaf.reset(sk_X509_new_null());
if (!chain_without_leaf) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
return 0;
}
}
}
X509 *leaf = nullptr;
bssl::UniquePtr<X509> leaf;
for (CRYPTO_BUFFER *cert : sess->certs.get()) {
UniquePtr<X509> x509(X509_parse_from_buffer(cert));
if (!x509) {
@ -298,7 +307,11 @@ static int ssl_crypto_x509_session_cache_objects(SSL_SESSION *sess) {
return 0;
}
if (leaf == nullptr) {
leaf = x509.get();
leaf = UpRef(x509);
} else if (chain_without_leaf &&
!PushToStack(chain_without_leaf.get(), UpRef(x509))) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
return 0;
}
if (!PushToStack(chain.get(), std::move(x509))) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
@ -308,26 +321,28 @@ static int ssl_crypto_x509_session_cache_objects(SSL_SESSION *sess) {
sk_X509_pop_free(sess->x509_chain, X509_free);
sess->x509_chain = chain.release();
sk_X509_pop_free(sess->x509_chain_without_leaf, X509_free);
sess->x509_chain_without_leaf = NULL;
sess->x509_chain_without_leaf = chain_without_leaf.release();
X509_free(sess->x509_peer);
if (leaf != NULL) {
X509_up_ref(leaf);
}
sess->x509_peer = leaf;
sess->x509_peer = leaf.release();
return 1;
}
static int ssl_crypto_x509_session_dup(SSL_SESSION *new_session,
const SSL_SESSION *session) {
if (session->x509_peer != NULL) {
X509_up_ref(session->x509_peer);
new_session->x509_peer = session->x509_peer;
}
if (session->x509_chain != NULL) {
new_session->x509_peer = UpRef(session->x509_peer).release();
if (session->x509_chain != nullptr) {
new_session->x509_chain = X509_chain_up_ref(session->x509_chain);
if (new_session->x509_chain == NULL) {
if (new_session->x509_chain == nullptr) {
return 0;
}
}
if (session->x509_chain_without_leaf != nullptr) {
new_session->x509_chain_without_leaf =
X509_chain_up_ref(session->x509_chain_without_leaf);
if (new_session->x509_chain_without_leaf == nullptr) {
return 0;
}
}
@ -525,38 +540,17 @@ X509 *SSL_get_peer_certificate(const SSL *ssl) {
STACK_OF(X509) *SSL_get_peer_cert_chain(const SSL *ssl) {
check_ssl_x509_method(ssl);
if (ssl == NULL) {
return NULL;
if (ssl == nullptr) {
return nullptr;
}
SSL_SESSION *session = SSL_get_session(ssl);
if (session == NULL ||
session->x509_chain == NULL) {
return NULL;
}
if (!ssl->server) {
return session->x509_chain;
if (session == nullptr) {
return nullptr;
}
// OpenSSL historically didn't include the leaf certificate in the returned
// certificate chain, but only for servers.
if (session->x509_chain_without_leaf == NULL) {
session->x509_chain_without_leaf = sk_X509_new_null();
if (session->x509_chain_without_leaf == NULL) {
return NULL;
}
for (size_t i = 1; i < sk_X509_num(session->x509_chain); i++) {
X509 *cert = sk_X509_value(session->x509_chain, i);
if (!PushToStack(session->x509_chain_without_leaf, UpRef(cert))) {
sk_X509_pop_free(session->x509_chain_without_leaf, X509_free);
session->x509_chain_without_leaf = NULL;
return NULL;
}
}
}
return session->x509_chain_without_leaf;
return ssl->server ? session->x509_chain_without_leaf : session->x509_chain;
}
STACK_OF(X509) *SSL_get_peer_full_cert_chain(const SSL *ssl) {