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authorPeter Wu <peter@lekensteyn.nl>2020-05-04 00:16:40 +0200
committerPeter Wu <peter@lekensteyn.nl>2020-05-27 21:19:51 +0200
commit7be7c56be941192c0f9b4ba33a7cb1f12a821035 (patch)
tree548ee72b3cb3fe86071ea1990f2a48f9a91d04e1
parent6011a986ca3a4c162eb0daf9204fa5ddbc20a86e (diff)
wolfssl: add SSLKEYLOGFILE support
Tested following the same curl and tshark commands as in commit "vtls: Extract and simplify key log file handling from OpenSSL" using WolfSSL v4.4.0-stable-128-g5179503e8 from git master built with `./configure --enable-all --enable-debug CFLAGS=-DHAVE_SECRET_CALLBACK`. Full support for this feature requires certain wolfSSL build options, see "Availability note" in lib/vtls/wolfssl.c for details. Closes #5327
-rw-r--r--lib/vtls/wolfssl.c144
1 files changed, 144 insertions, 0 deletions
diff --git a/lib/vtls/wolfssl.c b/lib/vtls/wolfssl.c
index f022f93c1..8f7dd3abd 100644
--- a/lib/vtls/wolfssl.c
+++ b/lib/vtls/wolfssl.c
@@ -63,6 +63,7 @@
#include "sendf.h"
#include "inet_pton.h"
#include "vtls.h"
+#include "keylog.h"
#include "parsedate.h"
#include "connect.h" /* for the connect timeout */
#include "select.h"
@@ -99,6 +100,107 @@ struct ssl_backend_data {
static Curl_recv wolfssl_recv;
static Curl_send wolfssl_send;
+#ifdef OPENSSL_EXTRA
+/*
+ * Availability note:
+ * The TLS 1.3 secret callback (wolfSSL_set_tls13_secret_cb) was added in
+ * WolfSSL 4.4.0, but requires the -DHAVE_SECRET_CALLBACK build option. If that
+ * option is not set, then TLS 1.3 will not be logged.
+ * For TLS 1.2 and before, we use wolfSSL_get_keys().
+ * SSL_get_client_random and wolfSSL_get_keys require OPENSSL_EXTRA
+ * (--enable-opensslextra or --enable-all).
+ */
+#if defined(HAVE_SECRET_CALLBACK) && defined(WOLFSSL_TLS13)
+static int
+wolfssl_tls13_secret_callback(SSL *ssl, int id, const unsigned char *secret,
+ int secretSz, void *ctx)
+{
+ const char *label;
+ unsigned char client_random[SSL3_RANDOM_SIZE];
+ (void)ctx;
+
+ if(!ssl || !Curl_tls_keylog_enabled()) {
+ return 0;
+ }
+
+ switch(id) {
+ case CLIENT_EARLY_TRAFFIC_SECRET:
+ label = "CLIENT_EARLY_TRAFFIC_SECRET";
+ break;
+ case CLIENT_HANDSHAKE_TRAFFIC_SECRET:
+ label = "CLIENT_HANDSHAKE_TRAFFIC_SECRET";
+ break;
+ case SERVER_HANDSHAKE_TRAFFIC_SECRET:
+ label = "SERVER_HANDSHAKE_TRAFFIC_SECRET";
+ break;
+ case CLIENT_TRAFFIC_SECRET:
+ label = "CLIENT_TRAFFIC_SECRET_0";
+ break;
+ case SERVER_TRAFFIC_SECRET:
+ label = "SERVER_TRAFFIC_SECRET_0";
+ break;
+ case EARLY_EXPORTER_SECRET:
+ label = "EARLY_EXPORTER_SECRET";
+ break;
+ case EXPORTER_SECRET:
+ label = "EXPORTER_SECRET";
+ break;
+ default:
+ return 0;
+ }
+
+ if(SSL_get_client_random(ssl, client_random, SSL3_RANDOM_SIZE) == 0) {
+ /* Should never happen as wolfSSL_KeepArrays() was called before. */
+ return 0;
+ }
+
+ Curl_tls_keylog_write(label, client_random, secret, secretSz);
+ return 0;
+}
+#endif /* defined(HAVE_SECRET_CALLBACK) && defined(WOLFSSL_TLS13) */
+
+static void
+wolfssl_log_tls12_secret(SSL *ssl)
+{
+ unsigned char *ms, *sr, *cr;
+ unsigned int msLen, srLen, crLen, i, x = 0;
+
+#if LIBWOLFSSL_VERSION_HEX >= 0x0300d000 /* >= 3.13.0 */
+ /* wolfSSL_GetVersion is available since 3.13, we use it instead of
+ * SSL_version since the latter relies on OPENSSL_ALL (--enable-opensslall or
+ * --enable-all). Failing to perform this check could result in an unusable
+ * key log line when TLS 1.3 is actually negotiated. */
+ switch(wolfSSL_GetVersion(ssl)) {
+ case WOLFSSL_SSLV3:
+ case WOLFSSL_TLSV1:
+ case WOLFSSL_TLSV1_1:
+ case WOLFSSL_TLSV1_2:
+ break;
+ default:
+ /* TLS 1.3 does not use this mechanism, the "master secret" returned below
+ * is not directly usable. */
+ return;
+ }
+#endif
+
+ if(SSL_get_keys(ssl, &ms, &msLen, &sr, &srLen, &cr, &crLen) != SSL_SUCCESS) {
+ return;
+ }
+
+ /* Check for a missing master secret and skip logging. That can happen if
+ * curl rejects the server certificate and aborts the handshake.
+ */
+ for(i = 0; i < msLen; i++) {
+ x |= ms[i];
+ }
+ if(x == 0) {
+ return;
+ }
+
+ Curl_tls_keylog_write("CLIENT_RANDOM", cr, ms, msLen);
+}
+#endif /* OPENSSL_EXTRA */
+
static int do_file_type(const char *type)
{
if(!type || !type[0])
@@ -385,6 +487,17 @@ wolfssl_connect_step1(struct connectdata *conn,
}
#endif /* HAVE_ALPN */
+#ifdef OPENSSL_EXTRA
+ if(Curl_tls_keylog_enabled()) {
+ /* Ensure the Client Random is preserved. */
+ wolfSSL_KeepArrays(backend->handle);
+#if defined(HAVE_SECRET_CALLBACK) && defined(WOLFSSL_TLS13)
+ wolfSSL_set_tls13_secret_cb(backend->handle,
+ wolfssl_tls13_secret_callback, NULL);
+#endif
+ }
+#endif /* OPENSSL_EXTRA */
+
/* Check if there's a cached ID we can/should use here! */
if(SSL_SET_OPTION(primary.sessionid)) {
void *ssl_sessionid = NULL;
@@ -444,6 +557,31 @@ wolfssl_connect_step2(struct connectdata *conn,
}
ret = SSL_connect(backend->handle);
+
+#ifdef OPENSSL_EXTRA
+ if(Curl_tls_keylog_enabled()) {
+ /* If key logging is enabled, wait for the handshake to complete and then
+ * proceed with logging secrets (for TLS 1.2 or older).
+ *
+ * During the handshake (ret==-1), wolfSSL_want_read() is true as it waits
+ * for the server response. At that point the master secret is not yet
+ * available, so we must not try to read it.
+ * To log the secret on completion with a handshake failure, detect
+ * completion via the observation that there is nothing to read or write.
+ * Note that OpenSSL SSL_want_read() is always true here. If wolfSSL ever
+ * changes, the worst case is that no key is logged on error.
+ */
+ if(ret == SSL_SUCCESS ||
+ (!wolfSSL_want_read(backend->handle) &&
+ !wolfSSL_want_write(backend->handle))) {
+ wolfssl_log_tls12_secret(backend->handle);
+ /* Client Random and master secrets are no longer needed, erase these.
+ * Ignored while the handshake is still in progress. */
+ wolfSSL_FreeArrays(backend->handle);
+ }
+ }
+#endif /* OPENSSL_EXTRA */
+
if(ret != 1) {
char error_buffer[WOLFSSL_MAX_ERROR_SZ];
int detail = SSL_get_error(backend->handle, ret);
@@ -750,6 +888,9 @@ static size_t Curl_wolfssl_version(char *buffer, size_t size)
static int Curl_wolfssl_init(void)
{
+#ifdef OPENSSL_EXTRA
+ Curl_tls_keylog_open();
+#endif
return (wolfSSL_Init() == SSL_SUCCESS);
}
@@ -757,6 +898,9 @@ static int Curl_wolfssl_init(void)
static void Curl_wolfssl_cleanup(void)
{
wolfSSL_Cleanup();
+#ifdef OPENSSL_EXTRA
+ Curl_tls_keylog_close();
+#endif
}