From a92ca561bc91f4ebd2f53578e82058efcde61aed Mon Sep 17 00:00:00 2001 From: David Benjamin Date: Mon, 23 Oct 2017 19:13:05 -0400 Subject: [PATCH] Fix weak digest in TLS 1.2 with SNI. MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 1ce95f19601bbc6bfd24092c76c8f8105124e857 was incomplete and did not handle the case when SSL_set_SSL_CTX was called from the cert_cb callback rather than the SNI callback. The consequence is any server using OpenSSL 1.0.2 and the cert_cb callback for SNI only ever signs a weak digest, SHA-1, even when connecting to clients which use secure ones. Fix this and add regression tests for both this and the original issue. Fixes #4554. Reviewed-by: Emilia Käsper Reviewed-by: Matt Caswell (Merged from https://github.com/openssl/openssl/pull/4577) --- ssl/ssl_lib.c | 4 +++ ssl/ssltest.c | 71 ++++++++++++++++++++++++++++++++++++++++++++------- test/testssl | 9 +++++++ 3 files changed, 75 insertions(+), 9 deletions(-) diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c index 8466da0e97..3539f4b8d2 100644 --- a/ssl/ssl_lib.c +++ b/ssl/ssl_lib.c @@ -3180,6 +3180,7 @@ SSL_CTX *SSL_set_SSL_CTX(SSL *ssl, SSL_CTX *ctx) #endif ssl->cert = ssl_cert_dup(ctx->cert); if (ocert) { + int i; /* Preserve any already negotiated parameters */ if (ssl->server) { ssl->cert->peer_sigalgs = ocert->peer_sigalgs; @@ -3189,6 +3190,9 @@ SSL_CTX *SSL_set_SSL_CTX(SSL *ssl, SSL_CTX *ctx) ssl->cert->ciphers_rawlen = ocert->ciphers_rawlen; ocert->ciphers_raw = NULL; } + for (i = 0; i < SSL_PKEY_NUM; i++) { + ssl->cert->pkeys[i].digest = ocert->pkeys[i].digest; + } #ifndef OPENSSL_NO_TLSEXT ssl->cert->alpn_proposed = ocert->alpn_proposed; ssl->cert->alpn_proposed_len = ocert->alpn_proposed_len; diff --git a/ssl/ssltest.c b/ssl/ssltest.c index b75cac61fb..2d6141cd95 100644 --- a/ssl/ssltest.c +++ b/ssl/ssltest.c @@ -315,6 +315,9 @@ static int s_ticket1 = 0; static int s_ticket2 = 0; static int c_ticket = 0; static int ticket_expect = -1; +static int sni_in_cert_cb = 0; +static const char *client_sigalgs = NULL; +static const char *server_digest_expect = NULL; static int servername_cb(SSL *s, int *ad, void *arg) { @@ -355,6 +358,11 @@ static int verify_servername(SSL *client, SSL *server) BIO_printf(bio_stdout, "Servername: context is unknown\n"); return -1; } +static int cert_cb(SSL *ssl, void *arg) +{ + int unused; + return servername_cb(ssl, &unused, NULL) != SSL_TLSEXT_ERR_ALERT_FATAL; +} static int verify_ticket(SSL* ssl) { @@ -371,6 +379,20 @@ static int verify_ticket(SSL* ssl) return -1; } +static int verify_server_digest(SSL* ssl) +{ + int nid = NID_undef; + + if (server_digest_expect == NULL) + return 0; + SSL_get_peer_signature_nid(ssl, &nid); + if (strcmp(server_digest_expect, OBJ_nid2sn(nid)) == 0) + return 1; + BIO_printf(bio_stdout, "Expected server digest %s, got %s.\n", + server_digest_expect, OBJ_nid2sn(nid)); + return -1; +} + /*- * next_protos_parse parses a comma separated list of strings into a string * in a format suitable for passing to SSL_CTX_set_next_protos_advertised. @@ -831,6 +853,7 @@ static void sv_usage(void) #endif #ifndef OPENSSL_NO_TLS1 fprintf(stderr, " -tls1 - use TLSv1\n"); + fprintf(stderr, " -tls12 - use TLSv1.2\n"); #endif #ifndef OPENSSL_NO_DTLS fprintf(stderr, " -dtls1 - use DTLSv1\n"); @@ -884,6 +907,9 @@ static void sv_usage(void) fprintf(stderr, " -c_ticket - enable/disable session tickets on the client\n"); fprintf(stderr, " -ticket_expect - indicate that the client should (or should not) have a ticket\n"); #endif + fprintf(stderr, " -sni_in_cert_cb - have the server handle SNI in the certificate callback\n"); + fprintf(stderr, " -client_sigalgs arg - the signature algorithms to configure on the client\n"); + fprintf(stderr, " -server_digest_expect arg - the expected server signing digest\n"); } static void print_details(SSL *c_ssl, const char *prefix) @@ -1010,7 +1036,7 @@ int main(int argc, char *argv[]) int badop = 0; int bio_pair = 0; int force = 0; - int dtls1 = 0, dtls12 = 0, tls1 = 0, ssl2 = 0, ssl3 = 0, ret = 1; + int dtls1 = 0, dtls12 = 0, tls1 = 0, tls12 = 0, ssl2 = 0, ssl3 = 0, ret = 1; int client_auth = 0; int server_auth = 0, i; struct app_verify_arg app_verify_arg = @@ -1164,6 +1190,11 @@ int main(int argc, char *argv[]) no_protocol = 1; #endif tls1 = 1; + } else if (strcmp(*argv, "-tls12") == 0) { +#ifdef OPENSSL_NO_TLS1 + no_protocol = 1; +#endif + tls12 = 1; } else if (strcmp(*argv, "-ssl3") == 0) { #ifdef OPENSSL_NO_SSL3_METHOD no_protocol = 1; @@ -1343,6 +1374,16 @@ int main(int argc, char *argv[]) else if (strcmp(*argv, "no") == 0) ticket_expect = 0; #endif + } else if (strcmp(*argv, "-sni_in_cert_cb") == 0) { + sni_in_cert_cb = 1; + } else if (strcmp(*argv, "-client_sigalgs") == 0) { + if (--argc < 1) + goto bad; + client_sigalgs = *(++argv); + } else if (strcmp(*argv, "-server_digest_expect") == 0) { + if (--argc < 1) + goto bad; + server_digest_expect = *(++argv); } else { fprintf(stderr, "unknown option %s\n", *argv); badop = 1; @@ -1373,9 +1414,9 @@ int main(int argc, char *argv[]) goto end; } - if (ssl2 + ssl3 + tls1 + dtls1 + dtls12 > 1) { - fprintf(stderr, "At most one of -ssl2, -ssl3, -tls1, -dtls1 or -dtls12 should " - "be requested.\n"); + if (ssl2 + ssl3 + tls1 + tls12 + dtls1 + dtls12 > 1) { + fprintf(stderr, "At most one of -ssl2, -ssl3, -tls1, -tls12, -dtls1 or " + "-dtls12 should be requested.\n"); EXIT(1); } @@ -1391,10 +1432,11 @@ int main(int argc, char *argv[]) goto end; } - if (!ssl2 && !ssl3 && !tls1 && !dtls1 && !dtls12 && number > 1 && !reuse && !force) { + if (!ssl2 && !ssl3 && !tls1 && !tls12 && !dtls1 && !dtls12 && number > 1 + && !reuse && !force) { fprintf(stderr, "This case cannot work. Use -f to perform " "the test anyway (and\n-d to see what happens), " - "or add one of ssl2, -ssl3, -tls1, -dtls1, -dtls12, -reuse\n" + "or add one of ssl2, -ssl3, -tls1, -tls12, -dtls1, -dtls12, -reuse\n" "to avoid protocol mismatch.\n"); EXIT(1); } @@ -1458,7 +1500,7 @@ int main(int argc, char *argv[]) #endif /* - * At this point, ssl2/ssl3/tls1 is only set if the protocol is + * At this point, ssl2/ssl3/tls1/tls12 is only set if the protocol is * available. (Otherwise we exit early.) However the compiler doesn't * know this, so we ifdef. */ @@ -1482,6 +1524,8 @@ int main(int argc, char *argv[]) #ifndef OPENSSL_NO_TLS1 if (tls1) meth = TLSv1_method(); + else if (tls12) + meth = TLSv1_2_method(); else #endif meth = SSLv23_method(); @@ -1778,8 +1822,12 @@ int main(int argc, char *argv[]) OPENSSL_free(alpn); } - if (sn_server1 || sn_server2) - SSL_CTX_set_tlsext_servername_callback(s_ctx, servername_cb); + if (sn_server1 || sn_server2) { + if (sni_in_cert_cb) + SSL_CTX_set_cert_cb(s_ctx, cert_cb, NULL); + else + SSL_CTX_set_tlsext_servername_callback(s_ctx, servername_cb); + } #ifndef OPENSSL_NO_TLSEXT if (s_ticket1 == 0) @@ -1799,6 +1847,9 @@ int main(int argc, char *argv[]) SSL_CTX_set_options(c_ctx, SSL_OP_NO_TICKET); #endif + if (client_sigalgs != NULL) + SSL_CTX_set1_sigalgs_list(c_ctx, client_sigalgs); + c_ssl = SSL_new(c_ctx); s_ssl = SSL_new(s_ctx); @@ -1864,6 +1915,8 @@ int main(int argc, char *argv[]) ret = 1; if (verify_ticket(c_ssl) < 0) ret = 1; + if (verify_server_digest(c_ssl) < 0) + ret = 1; SSL_free(s_ssl); SSL_free(c_ssl); diff --git a/test/testssl b/test/testssl index d7dda6e9a5..21bc4d8140 100644 --- a/test/testssl +++ b/test/testssl @@ -292,6 +292,15 @@ if [ -z "$extra" -a `uname -m` = "x86_64" ]; then $ssltest -cipher AES128-SHA256 -bytes 8m || exit 1 fi +############################################################################# +# Signature algorithms + SNI + +$ssltest -tls12 -sn_client server1 -sn_server1 server1 -sn_server2 server2 -sn_expect1 -client_sigalgs RSA+SHA256 -server_digest_expect SHA256 || exit 1 +$ssltest -tls12 -sn_client server1 -sn_server1 server1 -sn_server2 server2 -sn_expect1 -client_sigalgs RSA+SHA256 -server_digest_expect SHA256 -sni_in_cert_cb || exit 1 +# Switching SSL_CTX on SNI must not break signature algorithm negotiation. +$ssltest -tls12 -sn_client server2 -sn_server1 server1 -sn_server2 server2 -sn_expect2 -client_sigalgs RSA+SHA256 -server_digest_expect SHA256 || exit 1 +$ssltest -tls12 -sn_client server2 -sn_server1 server1 -sn_server2 server2 -sn_expect2 -client_sigalgs RSA+SHA256 -server_digest_expect SHA256 -sni_in_cert_cb || exit 1 + $ssltest -bio_pair -sn_client alice -sn_server1 alice -sn_server2 bob -s_ticket1 no -s_ticket2 no -c_ticket no -ticket_expect no || exit 1 $ssltest -bio_pair -sn_client alice -sn_server1 alice -sn_server2 bob -s_ticket1 no -s_ticket2 no -c_ticket yes -ticket_expect no || exit 1 -- 2.25.1