diff options
Diffstat (limited to 'modules/http/debug_opensslkeylog.c')
| -rw-r--r-- | modules/http/debug_opensslkeylog.c | 369 |
1 files changed, 369 insertions, 0 deletions
diff --git a/modules/http/debug_opensslkeylog.c b/modules/http/debug_opensslkeylog.c new file mode 100644 index 0000000..6709eb7 --- /dev/null +++ b/modules/http/debug_opensslkeylog.c @@ -0,0 +1,369 @@ +/* + * 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> + * SPDX-License-Identifier: GPL-3.0-or-later + * + * 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 + +#ifndef _GNU_SOURCE +# define _GNU_SOURCE /* for RTLD_NEXT */ +#endif + +#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 + +/* 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) + +#pragma GCC diagnostic ignored "-Wpedantic" +#pragma GCC diagnostic ignored "-Wunused-result" + +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("OPENSSLKEYLOGFILE"); + if (filename) { + /* ctime output is max 26 bytes, POSIX 1003.1-2017 */ + keylog_file_fd = open(filename, O_WRONLY | O_APPEND | O_CREAT, 0600); + if (keylog_file_fd >= 0) { + time_t timenow = time(NULL); + char txtnow[30] = { '#', ' ', 0 }; + ctime_r(&timenow, txtnow + 2); + /* file is opened successfully and there is no data (pos == 0) */ + write(keylog_file_fd, txtnow, strlen(txtnow)); + } + } +} + +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); +} |