commit 2f7c9b6ecb1a7855167b2c65781b2c4b1b014807 Author: Nick Mathewson nickm@torproject.org Date: Wed May 13 12:38:17 2015 -0400

Tweak rectify_client_ciphers to work with openssl 1.1

The key here is to never touch ssl->cipher_list directly, but only via SSL_get_ciphers(). But it's not so simple.

See, if there is no specialized cipher_list on the SSL object, SSL_get_ciphers returns the cipher_list on the SSL_CTX. But we sure don't want to modify that one! So we need to use SSL_set_cipher_list first to make sure that we really have a cipher list on the SSL object. --- src/common/tortls.c | 55 ++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 39 insertions(+), 16 deletions(-)

diff --git a/src/common/tortls.c b/src/common/tortls.c index 97352c0..08966b6 100644 --- a/src/common/tortls.c +++ b/src/common/tortls.c @@ -1800,21 +1800,46 @@ log_unsupported_ciphers(smartlist_t *unsupported) tor_free(joined); }

-/** Replace *<b>ciphers</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. +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(STACK_OF(SSL_CIPHER) **ciphers) +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; @@ -1835,21 +1860,21 @@ rectify_client_ciphers(STACK_OF(SSL_CIPHER) **ciphers) 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); + 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, cipher->id, cipher->name); }

/* 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 + * (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 (j < sk_SSL_CIPHER_num(ciphers)) + cipher = sk_SSL_CIPHER_value(ciphers, j); if (cipher && ((cipher->id >> 24) & 0xff) != 3) { /* Skip over non-v3 ciphers entirely. (This should no longer be * needed, thanks to saying !SSLv2 above.) */ @@ -1886,12 +1911,10 @@ rectify_client_ciphers(STACK_OF(SSL_CIPHER) **ciphers) smartlist_free(unsupported); }

- sk_SSL_CIPHER_free(*ciphers); - *ciphers = sk_SSL_CIPHER_dup(CLIENT_CIPHER_STACK); - tor_assert(*ciphers); + set_ssl_ciphers_to_list(ssl, CLIENT_CIPHER_STACK);

#else - (void)ciphers; + (void)ciphers; #endif }

@@ -1935,7 +1958,7 @@ tor_tls_new(int sock, int isServer) goto err; } if (!isServer) - rectify_client_ciphers(&result->ssl->cipher_list); + rectify_client_ciphers(result->ssl); result->socket = sock; bio = BIO_new_socket(sock, BIO_NOCLOSE); if (! bio) {