Add a callback for DDoS protection.
This callback receives information about the ClientHello and can decide
whether or not to allow the handshake to continue.
Change-Id: I21be28335fa74fedb5b73a310ee24310670fc923
Reviewed-on: https://boringssl-review.googlesource.com/3721
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h
index 19ed07b..82d632a 100644
--- a/include/openssl/ssl.h
+++ b/include/openssl/ssl.h
@@ -809,6 +809,11 @@
* will not call the callback a second time. */
int (*select_certificate_cb)(const struct ssl_early_callback_ctx *);
+ /* dos_protection_cb is called once the resumption decision for a ClientHello
+ * has been made. It returns one to continue the handshake or zero to
+ * abort. */
+ int (*dos_protection_cb) (const struct ssl_early_callback_ctx *);
+
/* quiet_shutdown is true if the connection should not send a close_notify on
* shutdown. */
int quiet_shutdown;
@@ -2228,6 +2233,12 @@
OPENSSL_EXPORT int SSL_cache_hit(SSL *s);
OPENSSL_EXPORT int SSL_is_server(SSL *s);
+/* SSL_CTX_set_dos_protection_cb sets a callback that is called once the
+ * resumption decision for a ClientHello has been made. It can return 1 to
+ * allow the handshake to continue or zero to cause the handshake to abort. */
+void SSL_CTX_set_dos_protection_cb(
+ SSL_CTX *ctx, int (*cb)(const struct ssl_early_callback_ctx *));
+
/* SSL_get_structure_sizes returns the sizes of the SSL, SSL_CTX and
* SSL_SESSION structures so that a test can ensure that outside code agrees on
* these values. */
diff --git a/ssl/s3_srvr.c b/ssl/s3_srvr.c
index ddff5c5..535c1df 100644
--- a/ssl/s3_srvr.c
+++ b/ssl/s3_srvr.c
@@ -1086,6 +1086,13 @@
}
}
+ if (s->ctx->dos_protection_cb != NULL && s->ctx->dos_protection_cb(&early_ctx) == 0) {
+ /* Connection rejected for DOS reasons. */
+ al = SSL_AD_ACCESS_DENIED;
+ OPENSSL_PUT_ERROR(SSL, ssl3_get_client_hello, SSL_R_CONNECTION_REJECTED);
+ goto f_err;
+ }
+
if (!CBS_get_u16_length_prefixed(&client_hello, &cipher_suites) ||
!CBS_get_u8_length_prefixed(&client_hello, &compression_methods) ||
CBS_len(&compression_methods) == 0) {
diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
index 68f4ccb..46b9cb6 100644
--- a/ssl/ssl_lib.c
+++ b/ssl/ssl_lib.c
@@ -3128,6 +3128,11 @@
int SSL_is_server(SSL *s) { return s->server; }
+void SSL_CTX_set_dos_protection_cb(
+ SSL_CTX *ctx, int (*cb)(const struct ssl_early_callback_ctx *)) {
+ ctx->dos_protection_cb = cb;
+}
+
void SSL_enable_fastradio_padding(SSL *s, char on_off) {
s->fastradio_padding = on_off;
}
diff --git a/ssl/test/bssl_shim.cc b/ssl/test/bssl_shim.cc
index ad4fa1a..3e712fc 100644
--- a/ssl/test/bssl_shim.cc
+++ b/ssl/test/bssl_shim.cc
@@ -308,6 +308,18 @@
}
}
+static int DDoSCallback(const struct ssl_early_callback_ctx *early_context) {
+ const TestConfig *config = GetConfigPtr(early_context->ssl);
+ static int callback_num = 0;
+
+ callback_num++;
+ if (config->fail_ddos_callback ||
+ (config->fail_second_ddos_callback && callback_num == 2)) {
+ return 0;
+ }
+ return 1;
+}
+
// Connect returns a new socket connected to localhost on |port| or -1 on
// error.
static int Connect(uint16_t port) {
@@ -600,6 +612,9 @@
SSL_set_options(ssl.get(), SSL_OP_NO_QUERY_MTU);
SSL_set_mtu(ssl.get(), config->mtu);
}
+ if (config->install_ddos_callback) {
+ SSL_CTX_set_dos_protection_cb(ssl_ctx, DDoSCallback);
+ }
int sock = Connect(config->port);
if (sock == -1) {
diff --git a/ssl/test/runner/runner.go b/ssl/test/runner/runner.go
index d1dbe87..3f26786 100644
--- a/ssl/test/runner/runner.go
+++ b/ssl/test/runner/runner.go
@@ -2037,6 +2037,37 @@
}
}
+func addDDoSCallbackTests() {
+ // DDoS callback.
+
+ for _, resume := range []bool{false, true} {
+ suffix := "Resume"
+ if resume {
+ suffix = "No" + suffix
+ }
+
+ testCases = append(testCases, testCase{
+ testType: serverTest,
+ name: "Server-DDoS-OK-" + suffix,
+ flags: []string{"-install-ddos-callback"},
+ resumeSession: resume,
+ })
+
+ failFlag := "-fail-ddos-callback"
+ if resume {
+ failFlag = "-fail-second-ddos-callback"
+ }
+ testCases = append(testCases, testCase{
+ testType: serverTest,
+ name: "Server-DDoS-Reject-" + suffix,
+ flags: []string{"-install-ddos-callback", failFlag},
+ resumeSession: resume,
+ shouldFail: true,
+ expectedError: ":CONNECTION_REJECTED:",
+ })
+ }
+}
+
func addVersionNegotiationTests() {
for i, shimVers := range tlsVersions {
// Assemble flags to disable all newer versions on the shim.
@@ -3029,6 +3060,7 @@
addCBCPaddingTests()
addCBCSplittingTests()
addClientAuthTests()
+ addDDoSCallbackTests()
addVersionNegotiationTests()
addMinimumVersionTests()
addD5BugTests()
diff --git a/ssl/test/test_config.cc b/ssl/test/test_config.cc
index 4db72b4..cbfc10f 100644
--- a/ssl/test/test_config.cc
+++ b/ssl/test/test_config.cc
@@ -75,6 +75,9 @@
{ "-implicit-handshake", &TestConfig::implicit_handshake },
{ "-use-early-callback", &TestConfig::use_early_callback },
{ "-fail-early-callback", &TestConfig::fail_early_callback },
+ { "-install-ddos-callback", &TestConfig::install_ddos_callback },
+ { "-fail-ddos-callback", &TestConfig::fail_ddos_callback },
+ { "-fail-second-ddos-callback", &TestConfig::fail_second_ddos_callback },
};
const Flag<std::string> kStringFlags[] = {
@@ -142,7 +145,9 @@
mtu(0),
implicit_handshake(false),
use_early_callback(false),
- fail_early_callback(false) {
+ fail_early_callback(false),
+ install_ddos_callback(false),
+ fail_ddos_callback(false) {
}
bool ParseConfig(int argc, char **argv, TestConfig *out_config) {
diff --git a/ssl/test/test_config.h b/ssl/test/test_config.h
index a54fb23..380e845 100644
--- a/ssl/test/test_config.h
+++ b/ssl/test/test_config.h
@@ -70,6 +70,9 @@
bool implicit_handshake;
bool use_early_callback;
bool fail_early_callback;
+ bool install_ddos_callback;
+ bool fail_ddos_callback;
+ bool fail_second_ddos_callback;
};
bool ParseConfig(int argc, char **argv, TestConfig *out_config);
