--- /dev/null
+/*
+ * Dumps master keys for OpenSSL clients to file. The format is documented at
+ * https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/Key_Log_Format
+ * Supports TLS 1.3 when used with OpenSSL 1.1.1.
+ *
+ * Copyright (C) 2014 Peter Wu <peter@lekensteyn.nl>
+ * Licensed under the terms of GPLv3 (or any later version) at your choice.
+ *
+ * Usage:
+ * cc sslkeylog.c -shared -o libsslkeylog.so -fPIC -ldl
+ * SSLKEYLOGFILE=premaster.txt LD_PRELOAD=./libsslkeylog.so openssl ...
+ */
+
+/*
+ * A single libsslkeylog.so supports multiple OpenSSL runtime versions. If you
+ * would like to build this library without OpenSSL development headers and do
+ * not require support for older OpenSSL versions, then disable it by defining
+ * the NO_OPENSSL_102_SUPPORT or NO_OPENSSL_110_SUPPORT macros.
+ */
+/* Define to drop OpenSSL <= 1.0.2 support and require OpenSSL >= 1.1.0. */
+//#define NO_OPENSSL_102_SUPPORT
+/* Define to drop OpenSSL <= 1.1.0 support and require OpenSSL >= 1.1.1. */
+//#define NO_OPENSSL_110_SUPPORT
+
+/* No OpenSSL 1.1.0 support implies no OpenSSL 1.0.2 support. */
+#ifdef NO_OPENSSL_110_SUPPORT
+# define NO_OPENSSL_102_SUPPORT
+#endif
+
+#define _GNU_SOURCE /* for RTLD_NEXT */
+#include <dlfcn.h>
+#ifndef NO_OPENSSL_102_SUPPORT
+# include <openssl/ssl.h>
+#endif /* ! NO_OPENSSL_102_SUPPORT */
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#ifndef OPENSSL_SONAME
+/* fallback library if OpenSSL is not already loaded. Other values to try:
+ * libssl.so.0.9.8 libssl.so.1.0.0 libssl.so.1.1 */
+# define OPENSSL_SONAME "libssl.so"
+#endif
+
+#define FIRSTLINE "# SSL key logfile generated by sslkeylog.c\n"
+#define FIRSTLINE_LEN (sizeof(FIRSTLINE) - 1)
+
+/* When building for OpenSSL 1.1.0 or newer, no headers are required. */
+#ifdef NO_OPENSSL_102_SUPPORT
+typedef struct ssl_st SSL;
+typedef struct ssl_ctx_st SSL_CTX;
+/* Extra definitions for OpenSSL 1.1.0 support when headers are unavailable. */
+# ifndef NO_OPENSSL_110_SUPPORT
+typedef struct ssl_session_st SSL_SESSION;
+# define SSL3_RANDOM_SIZE 32
+# define SSL_MAX_MASTER_KEY_LENGTH 48
+# define OPENSSL_VERSION_NUMBER 0x10100000L
+# endif /* ! NO_OPENSSL_110_SUPPORT */
+#endif /* ! NO_OPENSSL_102_SUPPORT */
+
+static int keylog_file_fd = -1;
+
+/* Legacy routines for dumping TLS <= 1.2 secrets on older OpenSSL versions. */
+#ifndef NO_OPENSSL_110_SUPPORT
+#define PREFIX "CLIENT_RANDOM "
+#define PREFIX_LEN (sizeof(PREFIX) - 1)
+
+static inline void put_hex(char *buffer, int pos, char c)
+{
+ unsigned char c1 = ((unsigned char) c) >> 4;
+ unsigned char c2 = c & 0xF;
+ buffer[pos] = c1 < 10 ? '0' + c1 : 'A' + c1 - 10;
+ buffer[pos+1] = c2 < 10 ? '0' + c2 : 'A' + c2 - 10;
+}
+
+static void dump_to_fd(int fd, unsigned char *client_random,
+ unsigned char *master_key, int master_key_length)
+{
+ int pos, i;
+ char line[PREFIX_LEN + 2 * SSL3_RANDOM_SIZE + 1 +
+ 2 * SSL_MAX_MASTER_KEY_LENGTH + 1];
+
+ memcpy(line, PREFIX, PREFIX_LEN);
+ pos = PREFIX_LEN;
+ /* Client Random for SSLv3/TLS */
+ for (i = 0; i < SSL3_RANDOM_SIZE; i++) {
+ put_hex(line, pos, client_random[i]);
+ pos += 2;
+ }
+ line[pos++] = ' ';
+ /* Master Secret (size is at most SSL_MAX_MASTER_KEY_LENGTH) */
+ for (i = 0; i < master_key_length; i++) {
+ put_hex(line, pos, master_key[i]);
+ pos += 2;
+ }
+ line[pos++] = '\n';
+ /* Write at once rather than using buffered I/O. Perhaps there is concurrent
+ * write access so do not write hex values one by one. */
+ write(fd, line, pos);
+}
+#endif /* ! NO_OPENSSL_110_SUPPORT */
+
+static void init_keylog_file(void)
+{
+ if (keylog_file_fd >= 0)
+ return;
+
+ const char *filename = getenv("SSLKEYLOGFILE");
+ if (filename) {
+ keylog_file_fd = open(filename, O_WRONLY | O_APPEND | O_CREAT, 0644);
+ if (keylog_file_fd >= 0 && lseek(keylog_file_fd, 0, SEEK_END) == 0) {
+ /* file is opened successfully and there is no data (pos == 0) */
+ write(keylog_file_fd, FIRSTLINE, FIRSTLINE_LEN);
+ }
+ }
+}
+
+static inline void *try_lookup_symbol(const char *sym, int optional)
+{
+ void *func = dlsym(RTLD_NEXT, sym);
+ if (!func && optional && dlsym(RTLD_NEXT, "SSL_new")) {
+ /* Symbol not found, but an old OpenSSL version was actually loaded. */
+ return NULL;
+ }
+ /* Symbol not found, OpenSSL is not loaded (linked) so try to load it
+ * manually. This is error-prone as it depends on a fixed library name.
+ * Perhaps it should be an env name? */
+ if (!func) {
+ void *handle = dlopen(OPENSSL_SONAME, RTLD_LAZY);
+ if (!handle) {
+ fprintf(stderr, "Lookup error for %s: %s\n", sym, dlerror());
+ abort();
+ }
+ func = dlsym(handle, sym);
+ if (!func && !optional) {
+ fprintf(stderr, "Cannot lookup %s\n", sym);
+ abort();
+ }
+ dlclose(handle);
+ }
+ return func;
+}
+
+static inline void *lookup_symbol(const char *sym)
+{
+ return try_lookup_symbol(sym, 0);
+}
+
+#ifndef NO_OPENSSL_110_SUPPORT
+typedef struct ssl_tap_state {
+ int master_key_length;
+ unsigned char master_key[SSL_MAX_MASTER_KEY_LENGTH];
+
+} ssl_tap_state_t;
+
+static inline SSL_SESSION *ssl_get_session(const SSL *ssl)
+{
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L
+ static SSL_SESSION *(*func)();
+ if (!func) {
+ func = lookup_symbol("SSL_get_session");
+ }
+ return func(ssl);
+#else
+ return ssl->session;
+#endif
+}
+
+static void copy_master_secret(const SSL_SESSION *session,
+ unsigned char *master_key_out, int *keylen_out)
+{
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L
+ static size_t (*func)();
+ if (!func) {
+ func = lookup_symbol("SSL_SESSION_get_master_key");
+ }
+ *keylen_out = func(session, master_key_out, SSL_MAX_MASTER_KEY_LENGTH);
+#else
+ if (session->master_key_length > 0) {
+ *keylen_out = session->master_key_length;
+ memcpy(master_key_out, session->master_key,
+ session->master_key_length);
+ }
+#endif
+}
+
+static void copy_client_random(const SSL *ssl, unsigned char *client_random)
+{
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L
+ static size_t (*func)();
+ if (!func) {
+ func = lookup_symbol("SSL_get_client_random");
+ }
+ /* ssl->s3 is not checked in openssl 1.1.0-pre6, but let's assume that
+ * we have a valid SSL context if we have a non-NULL session. */
+ func(ssl, client_random, SSL3_RANDOM_SIZE);
+#else
+ if (ssl->s3) {
+ memcpy(client_random, ssl->s3->client_random, SSL3_RANDOM_SIZE);
+ }
+#endif
+}
+
+/* non-NULL if the new OpenSSL 1.1.1 keylog API is supported. */
+static int supports_keylog_api(void)
+{
+ static int supported = -1;
+ if (supported == -1) {
+ supported = try_lookup_symbol("SSL_CTX_set_keylog_callback", 1) != NULL;
+ }
+ return supported;
+}
+
+/* Copies SSL state for later comparison in tap_ssl_key. */
+static void ssl_tap_state_init(ssl_tap_state_t *state, const SSL *ssl)
+{
+ if (supports_keylog_api()) {
+ /* Favor using the callbacks API to extract secrets. */
+ return;
+ }
+
+ const SSL_SESSION *session = ssl_get_session(ssl);
+
+ memset(state, 0, sizeof(ssl_tap_state_t));
+ if (session) {
+ copy_master_secret(session, state->master_key, &state->master_key_length);
+ }
+}
+
+#define SSL_TAP_STATE(state, ssl) \
+ ssl_tap_state_t state; \
+ ssl_tap_state_init(&state, ssl)
+
+static void tap_ssl_key(const SSL *ssl, ssl_tap_state_t *state)
+{
+ if (supports_keylog_api()) {
+ /* Favor using the callbacks API to extract secrets. */
+ return;
+ }
+
+ const SSL_SESSION *session = ssl_get_session(ssl);
+ unsigned char client_random[SSL3_RANDOM_SIZE];
+ unsigned char master_key[SSL_MAX_MASTER_KEY_LENGTH];
+ int master_key_length = 0;
+
+ if (session) {
+ copy_master_secret(session, master_key, &master_key_length);
+ /* Assume we have a client random if the master key is set. */
+ if (master_key_length > 0) {
+ copy_client_random(ssl, client_random);
+ }
+ }
+
+ /* Write the logfile when the master key is available for SSLv3/TLSv1. */
+ if (master_key_length > 0) {
+ /* Skip writing keys if it did not change. */
+ if (state->master_key_length == master_key_length &&
+ memcmp(state->master_key, master_key, master_key_length) == 0) {
+ return;
+ }
+
+ init_keylog_file();
+ if (keylog_file_fd >= 0) {
+ dump_to_fd(keylog_file_fd, client_random, master_key,
+ master_key_length);
+ }
+ }
+}
+
+int SSL_connect(SSL *ssl)
+{
+ static int (*func)();
+ if (!func) {
+ func = lookup_symbol(__func__);
+ }
+ SSL_TAP_STATE(state, ssl);
+ int ret = func(ssl);
+ tap_ssl_key(ssl, &state);
+ return ret;
+}
+
+int SSL_do_handshake(SSL *ssl)
+{
+ static int (*func)();
+ if (!func) {
+ func = lookup_symbol(__func__);
+ }
+ SSL_TAP_STATE(state, ssl);
+ int ret = func(ssl);
+ tap_ssl_key(ssl, &state);
+ return ret;
+}
+
+int SSL_accept(SSL *ssl)
+{
+ static int (*func)();
+ if (!func) {
+ func = lookup_symbol(__func__);
+ }
+ SSL_TAP_STATE(state, ssl);
+ int ret = func(ssl);
+ tap_ssl_key(ssl, &state);
+ return ret;
+}
+
+int SSL_read(SSL *ssl, void *buf, int num)
+{
+ static int (*func)();
+ if (!func) {
+ func = lookup_symbol(__func__);
+ }
+ SSL_TAP_STATE(state, ssl);
+ int ret = func(ssl, buf, num);
+ tap_ssl_key(ssl, &state);
+ return ret;
+}
+
+int SSL_write(SSL *ssl, const void *buf, int num)
+{
+ static int (*func)();
+ if (!func) {
+ func = lookup_symbol(__func__);
+ }
+ SSL_TAP_STATE(state, ssl);
+ int ret = func(ssl, buf, num);
+ tap_ssl_key(ssl, &state);
+ return ret;
+}
+#endif /* ! NO_OPENSSL_110_SUPPORT */
+
+/* Key extraction via the new OpenSSL 1.1.1 API. */
+static void keylog_callback(const SSL *ssl, const char *line)
+{
+ init_keylog_file();
+ if (keylog_file_fd >= 0) {
+ write(keylog_file_fd, line, strlen(line));
+ write(keylog_file_fd, "\n", 1);
+ }
+}
+
+SSL *SSL_new(SSL_CTX *ctx)
+{
+ static SSL *(*func)();
+ static void (*set_keylog_cb)();
+ if (!func) {
+ func = lookup_symbol(__func__);
+#ifdef NO_OPENSSL_110_SUPPORT
+ /* The new API MUST be available since OpenSSL 1.1.1. */
+ set_keylog_cb = lookup_symbol("SSL_CTX_set_keylog_callback");
+#else /* ! NO_OPENSSL_110_SUPPORT */
+ /* May be NULL if used with an older OpenSSL runtime library. */
+ set_keylog_cb = try_lookup_symbol("SSL_CTX_set_keylog_callback", 1);
+#endif /* ! NO_OPENSSL_110_SUPPORT */
+ }
+ if (set_keylog_cb) {
+ /* Override any previous key log callback. */
+ set_keylog_cb(ctx, keylog_callback);
+ }
+ return func(ctx);
+}
projects / thirdparty / knot-resolver.git / commitdiff
