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Merge remote-tracking branch 'public/bug15760_hard_026_v2'

Browse Source 
Conflicts:
	src/common/tortls.c
This commit is contained in:
Nick Mathewson 2015-06-02 13:45:27 -04:00
commit 0030765e04
2 changed files with 109 additions and 198 deletions
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18
configure.ac
View File

@ -610,10 +610,28 @@ else
fi
AC_SUBST(TOR_OPENSSL_LIBS)
dnl Now check for particular openssl functions.
save_LIBS="$LIBS"
save_LDFLAGS="$LDFLAGS"
save_CPPFLAGS="$CPPFLAGS"
LIBS="$TOR_OPENSSL_LIBS $LIBS"
LDFLAGS="$TOR_LDFLAGS_openssl $LDFLAGS"
CPPFLAGS="$TOR_CPPFLAGS_openssl $CPPFLAGS"
AC_CHECK_MEMBERS([struct ssl_method_st.get_cipher_by_char], , ,
[#include <openssl/ssl.h>
])
AC_CHECK_FUNCS([ \
SSL_SESSION_get_master_key \
SSL_get_server_random \
SSL_get_client_ciphers \
SSL_get_client_random \
SSL_CIPHER_find \
])
LIBS="$save_LIBS"
LDFLAGS="$save_LDFLAGS"
CPPFLAGS="$save_CPPFLAGS"
dnl ------------------------------------------------------
dnl Where do you live, zlib? And how do we call you?

289
src/common/tortls.c
View File

@ -205,16 +205,6 @@ struct tor_tls_t {
void *callback_arg;
};
#ifdef V2_HANDSHAKE_CLIENT
/** An array of fake SSL_CIPHER objects that we use in order to trick OpenSSL
* in client mode into advertising the ciphers we want. See
* rectify_client_ciphers() for details. */
static SSL_CIPHER *CLIENT_CIPHER_DUMMIES = NULL;
/** A stack of SSL_CIPHER objects, some real, some fake.
* See rectify_client_ciphers() for details. */
static STACK_OF(SSL_CIPHER) *CLIENT_CIPHER_STACK = NULL;
#endif
/** The ex_data index in which we store a pointer to an SSL object's
* corresponding tor_tls_t object. */
static int tor_tls_object_ex_data_index = -1;
@ -531,12 +521,6 @@ tor_tls_free_all(void)
client_tls_context = NULL;
tor_tls_context_decref(ctx);
}
#ifdef V2_HANDSHAKE_CLIENT
if (CLIENT_CIPHER_DUMMIES)
tor_free(CLIENT_CIPHER_DUMMIES);
if (CLIENT_CIPHER_STACK)
sk_SSL_CIPHER_free(CLIENT_CIPHER_STACK);
#endif
}
/** We need to give OpenSSL a callback to verify certificates. This is
@ -727,7 +711,6 @@ const char UNRESTRICTED_SERVER_CIPHER_LIST[] =
* (SSL3_TXT_RSA_NULL_SHA). If you do this, you won't be able to communicate
* with any of the "real" Tors, though. */
#ifdef V2_HANDSHAKE_CLIENT
#define CIPHER(id, name) name ":"
#define XCIPHER(id, name)
/** List of ciphers that clients should advertise, omitting items that
@ -741,28 +724,6 @@ static const char CLIENT_CIPHER_LIST[] =
#undef CIPHER
#undef XCIPHER
/** Holds a cipher that we want to advertise, and its 2-byte ID. */
typedef struct cipher_info_t { unsigned id; const char *name; } cipher_info_t;
/** A list of all the ciphers that clients should advertise, including items
* that OpenSSL might not know about. */
static const cipher_info_t CLIENT_CIPHER_INFO_LIST[] = {
#define CIPHER(id, name) { id, name },
#define XCIPHER(id, name) { id, #name },
#include "ciphers.inc"
#undef CIPHER
#undef XCIPHER
};
/** The length of CLIENT_CIPHER_INFO_LIST and CLIENT_CIPHER_DUMMIES. */
static const int N_CLIENT_CIPHERS = ARRAY_LENGTH(CLIENT_CIPHER_INFO_LIST);
#endif
#ifndef V2_HANDSHAKE_CLIENT
#undef CLIENT_CIPHER_LIST
#define CLIENT_CIPHER_LIST (TLS1_TXT_DHE_RSA_WITH_AES_128_SHA ":" \
SSL3_TXT_EDH_RSA_DES_192_CBC3_SHA)
#endif
/** Free all storage held in <b>cert</b> */
void
tor_x509_cert_free(tor_x509_cert_t *cert)
@ -1440,7 +1401,7 @@ static int
find_cipher_by_id(const SSL *ssl, const SSL_METHOD *m, uint16_t cipher)
{
const SSL_CIPHER *c;
#if OPENSSL_VERSION_NUMBER >= OPENSSL_V_SERIES(1,0,2)
#ifdef HAVE_SSL_CIPHER_FIND
{
unsigned char cipherid[3];
tor_assert(ssl);
@ -1597,13 +1558,19 @@ tor_tls_classify_client_ciphers(const SSL *ssl,
static int
tor_tls_client_is_using_v2_ciphers(const SSL *ssl)
{
STACK_OF(SSL_CIPHER) *ciphers;
#ifdef HAVE_SSL_GET_CLIENT_CIPHERS
ciphers = SSL_get_ciphers(ssl);
#else
SSL_SESSION *session;
if (!(session = SSL_get_session((SSL *)ssl))) {
log_info(LD_NET, "No session on TLS?");
return CIPHERS_ERR;
}
ciphers = session->ciphers;
#endif
return tor_tls_classify_client_ciphers(ssl, session->ciphers) >= CIPHERS_V2;
return tor_tls_classify_client_ciphers(ssl, ciphers) >= CIPHERS_V2;
}
/** Invoked when we're accepting a connection on <b>ssl</b>, and the connection
@ -1702,150 +1669,6 @@ tor_tls_setup_session_secret_cb(tor_tls_t *tls)
SSL_set_session_secret_cb(tls->ssl, tor_tls_session_secret_cb, NULL);
}
/** Explain which ciphers we're missing. */
static void
log_unsupported_ciphers(smartlist_t *unsupported)
{
char *joined;
log_notice(LD_NET, "We weren't able to find support for all of the "
"TLS ciphersuites that we wanted to advertise. This won't "
"hurt security, but it might make your Tor (if run as a client) "
"more easy for censors to block.");
if (SSLeay() < 0x10000000L) {
log_notice(LD_NET, "To correct this, use a more recent OpenSSL, "
"built without disabling any secure ciphers or features.");
} else {
log_notice(LD_NET, "To correct this, use a version of OpenSSL "
"built with none of its ciphers disabled.");
}
joined = smartlist_join_strings(unsupported, ":", 0, NULL);
log_info(LD_NET, "The unsupported ciphers were: %s", joined);
tor_free(joined);
}
static void
set_ssl_ciphers_to_list(SSL *ssl, STACK_OF(SSL_CIPHER) *stack)
{
STACK_OF(SSL_CIPHER) *ciphers;
int r, i;
/* #1: ensure that the ssl object has its own list of ciphers. Otherwise we
* might be about to stomp the SSL_CTX ciphers list. */
r = SSL_set_cipher_list(ssl, "HIGH");
tor_assert(r);
/* #2: Grab ssl_ciphers and clear it. */
ciphers = SSL_get_ciphers(ssl);
tor_assert(ciphers);
sk_SSL_CIPHER_zero(ciphers);
/* #3: Copy the elements from stack. */
for (i = 0; i < sk_SSL_CIPHER_num(stack); ++i) {
SSL_CIPHER *c = sk_SSL_CIPHER_value(stack, i);
sk_SSL_CIPHER_push(ciphers, c);
}
}
/** Replace the ciphers on <b>ssl</b> with a new list of SSL ciphersuites:
* specifically, a list designed to mimic a common web browser. We might not
* be able to do that if OpenSSL doesn't support all the ciphers we want.
* Some of the ciphers in the list won't actually be implemented by OpenSSL:
* that's okay so long as the server doesn't select them.
*
* [If the server <b>does</b> select a bogus cipher, we won't crash or
* anything; we'll just fail later when we try to look up the cipher in
* ssl->cipher_list_by_id.]
*/
static void
rectify_client_ciphers(SSL *ssl)
{
#ifdef V2_HANDSHAKE_CLIENT
if (PREDICT_UNLIKELY(!CLIENT_CIPHER_STACK)) {
STACK_OF(SSL_CIPHER) *ciphers = SSL_get_ciphers(ssl);
/* We need to set CLIENT_CIPHER_STACK to an array of the ciphers
* we want to use/advertise. */
int i = 0, j = 0;
smartlist_t *unsupported = smartlist_new();
/* First, create a dummy SSL_CIPHER for every cipher. */
CLIENT_CIPHER_DUMMIES =
tor_malloc_zero(sizeof(SSL_CIPHER)*N_CLIENT_CIPHERS);
for (i=0; i < N_CLIENT_CIPHERS; ++i) {
CLIENT_CIPHER_DUMMIES[i].valid = 1;
/* The "3<<24" here signifies that the cipher is supposed to work with
* SSL3 and TLS1. */
CLIENT_CIPHER_DUMMIES[i].id = CLIENT_CIPHER_INFO_LIST[i].id | (3<<24);
CLIENT_CIPHER_DUMMIES[i].name = CLIENT_CIPHER_INFO_LIST[i].name;
}
CLIENT_CIPHER_STACK = sk_SSL_CIPHER_new_null();
tor_assert(CLIENT_CIPHER_STACK);
log_debug(LD_NET, "List was: %s", CLIENT_CIPHER_LIST);
for (j = 0; j < sk_SSL_CIPHER_num(ciphers); ++j) {
SSL_CIPHER *cipher = sk_SSL_CIPHER_value(ciphers, j);
log_debug(LD_NET, "Cipher %d: %lx %s", j,
SSL_CIPHER_get_id(cipher), SSL_CIPHER_get_name(cipher));
}
/* Then copy as many ciphers as we can from the good list, inserting
* dummies as needed. Let j be an index into list of ciphers we have
* (ciphers) and let i be an index into the ciphers we want
* (CLIENT_INFO_CIPHER_LIST). We are building a list of ciphers in
* CLIENT_CIPHER_STACK.
*/
for (i = j = 0; i < N_CLIENT_CIPHERS; ) {
SSL_CIPHER *cipher = NULL;
if (j < sk_SSL_CIPHER_num(ciphers))
cipher = sk_SSL_CIPHER_value(ciphers, j);
if (cipher && ((SSL_CIPHER_get_id(cipher) >> 24) & 0xff) != 3) {
/* Skip over non-v3 ciphers entirely. (This should no longer be
* needed, thanks to saying !SSLv2 above.) */
log_debug(LD_NET, "Skipping v%d cipher %s",
(int)((SSL_CIPHER_get_id(cipher)>>24) & 0xff),
SSL_CIPHER_get_name(cipher));
++j;
} else if (cipher &&
(SSL_CIPHER_get_id(cipher) & 0xffff) ==
CLIENT_CIPHER_INFO_LIST[i].id) {
/* "cipher" is the cipher we expect. Put it on the list. */
log_debug(LD_NET, "Found cipher %s", SSL_CIPHER_get_name(cipher));
sk_SSL_CIPHER_push(CLIENT_CIPHER_STACK, cipher);
++j;
++i;
} else if (!strcmp(CLIENT_CIPHER_DUMMIES[i].name,
"SSL_RSA_FIPS_WITH_3DES_EDE_CBC_SHA")) {
/* We found bogus cipher 0xfeff, which OpenSSL doesn't support and
* never has. For this one, we need a dummy. */
log_debug(LD_NET, "Inserting fake %s", CLIENT_CIPHER_DUMMIES[i].name);
sk_SSL_CIPHER_push(CLIENT_CIPHER_STACK, &CLIENT_CIPHER_DUMMIES[i]);
++i;
} else {
/* OpenSSL doesn't have this one. */
log_debug(LD_NET, "Completely omitting unsupported cipher %s",
CLIENT_CIPHER_INFO_LIST[i].name);
smartlist_add(unsupported, (char*) CLIENT_CIPHER_INFO_LIST[i].name);
++i;
}
}
if (smartlist_len(unsupported))
log_unsupported_ciphers(unsupported);
smartlist_free(unsupported);
}
set_ssl_ciphers_to_list(ssl, CLIENT_CIPHER_STACK);
#else
(void)ciphers;
#endif
}
/** Create a new TLS object from a file descriptor, and a flag to
* determine whether it is functioning as a server.
*/
@ -1885,8 +1708,6 @@ tor_tls_new(int sock, int isServer)
tor_free(result);
goto err;
}
if (!isServer)
rectify_client_ciphers(result->ssl);
result->socket = sock;
bio = BIO_new_socket(sock, BIO_NOCLOSE);
if (! bio) {
@ -2769,6 +2590,46 @@ tor_tls_server_got_renegotiate(tor_tls_t *tls)
return tls->got_renegotiate;
}
#ifndef HAVE_SSL_GET_CLIENT_RANDOM
static size_t
SSL_get_client_random(SSL *s, uint8_t *out, size_t len)
{
if (len == 0)
return SSL3_RANDOM_SIZE;
tor_assert(len == SSL3_RANDOM_SIZE);
tor_assert(s->s3);
memcpy(out, s->s3->client_random, len);
return len;
}
#endif
#ifndef HAVE_SSL_GET_SERVER_RANDOM
static size_t
SSL_get_server_random(SSL *s, uint8_t *out, size_t len)
{
if (len == 0)
return SSL3_RANDOM_SIZE;
tor_assert(len == SSL3_RANDOM_SIZE);
tor_assert(s->s3);
memcpy(out, s->s3->server_random, len);
return len;
}
#endif
#ifndef HAVE_SSL_SESSION_GET_MASTER_KEY
static size_t
SSL_SESSION_get_master_key(SSL_SESSION *s, uint8_t *out, size_t len)
{
if (len == 0)
return s->master_key_length;
tor_assert(len == (size_t)s->master_key_length);
tor_assert(s->master_key);
memcpy(out, s->master_key, len);
return len;
}
#endif
/** Set the DIGEST256_LEN buffer at <b>secrets_out</b> to the value used in
* the v3 handshake to prove that the client knows the TLS secrets for the
* connection <b>tls</b>. Return 0 on success, -1 on failure.
@ -2777,25 +2638,57 @@ MOCK_IMPL(int,
tor_tls_get_tlssecrets,(tor_tls_t *tls, uint8_t *secrets_out))
{
#define TLSSECRET_MAGIC "Tor V3 handshake TLS cross-certification"
char buf[128];
uint8_t buf[128];
size_t len;
tor_assert(tls);
tor_assert(tls->ssl);
tor_assert(tls->ssl->s3);
tor_assert(tls->ssl->session);
SSL *const ssl = tls->ssl;
SSL_SESSION *const session = SSL_get_session(ssl);
tor_assert(ssl);
tor_assert(session);
const size_t server_random_len = SSL_get_server_random(ssl, NULL, 0);
const size_t client_random_len = SSL_get_client_random(ssl, NULL, 0);
const size_t master_key_len = SSL_SESSION_get_master_key(session, NULL, 0);
tor_assert(server_random_len);
tor_assert(client_random_len);
tor_assert(master_key_len);
len = client_random_len + server_random_len + strlen(TLSSECRET_MAGIC) + 1;
tor_assert(len <= sizeof(buf));
{
size_t r = SSL_get_client_random(ssl, buf, client_random_len);
tor_assert(r == client_random_len);
}
{
size_t r = SSL_get_server_random(ssl, buf+client_random_len, server_random_len);
tor_assert(r == server_random_len);
}
uint8_t *master_key = tor_malloc_zero(master_key_len);
{
size_t r = SSL_SESSION_get_master_key(session, master_key, master_key_len);
tor_assert(r == master_key_len);
}
uint8_t *nextbuf = buf + client_random_len + server_random_len;
memcpy(nextbuf, TLSSECRET_MAGIC, strlen(TLSSECRET_MAGIC) + 1);
/*
The value is an HMAC, using the TLS master key as the HMAC key, of
client_random | server_random | TLSSECRET_MAGIC
*/
memcpy(buf + 0, tls->ssl->s3->client_random, 32);
memcpy(buf + 32, tls->ssl->s3->server_random, 32);
memcpy(buf + 64, TLSSECRET_MAGIC, strlen(TLSSECRET_MAGIC) + 1);
len = 64 + strlen(TLSSECRET_MAGIC) + 1;
crypto_hmac_sha256((char*)secrets_out,
(char*)tls->ssl->session->master_key,
tls->ssl->session->master_key_length,
buf, len);
(char*)master_key,
master_key_len,
(char*)buf, len);
memwipe(buf, 0, sizeof(buf));
memwipe(master_key, 0, master_key_len);
tor_free(master_key);
return 0;
}