From c589c34e619c8700ab16b152dd9c8ee58356b319 Mon Sep 17 00:00:00 2001 From: Benjamin Kaduk Date: Thu, 11 Jan 2018 11:47:12 -0600 Subject: [PATCH] Add support for the TLS 1.3 signature_algorithms_cert extension The new extension is like signature_algorithms, but only for the signature *on* the certificate we will present to the peer (the old signature_algorithms extension is still used for signatures that we *generate*, i.e., those over TLS data structures). We do not need to generate this extension, since we are the same implementation as our X.509 stack and can handle the same types of signatures, but we need to be prepared to receive it, and use the received information when selecting what certificate to present. There is a lot of interplay between signature_algorithms_cert and signature_algorithms, since both affect what certificate we can use, and thus the resulting signature algorithm used for TLS messages. So, apply signature_algorithms_cert (if present) as a filter on what certificates we can consider when choosing a certificate+sigalg pair. As part of this addition, we also remove the fallback code that let keys of type EVP_PKEY_RSA be used to generate RSA-PSS signatures -- the new rsa_pss_pss_* and rsa_pss_rsae_* signature schemes have pulled the key type into what is covered by the signature algorithm, so we should not apply this sort of compatibility workaround. Reviewed-by: Matt Caswell (Merged from https://github.com/openssl/openssl/pull/5068) --- crypto/err/openssl.txt | 3 +- include/openssl/sslerr.h | 3 +- include/openssl/tls1.h | 1 + ssl/s3_lib.c | 2 + ssl/ssl_err.c | 4 +- ssl/ssl_locl.h | 8 ++- ssl/statem/extensions.c | 18 ++++++ ssl/statem/extensions_srvr.c | 23 +++++++- ssl/statem/statem_clnt.c | 6 +- ssl/statem/statem_locl.h | 2 + ssl/t1_lib.c | 108 ++++++++++++++++++++--------------- 11 files changed, 126 insertions(+), 52 deletions(-) diff --git a/crypto/err/openssl.txt b/crypto/err/openssl.txt index accd83cadc..ed706da904 100644 --- a/crypto/err/openssl.txt +++ b/crypto/err/openssl.txt @@ -1,4 +1,4 @@ -# Copyright 1999-2018 The OpenSSL Project Authors. All Rights Reserved. +# Copyright 1999-2017 The OpenSSL Project Authors. All Rights Reserved. # # Licensed under the OpenSSL license (the "License"). You may not use # this file except in compliance with the License. You can obtain a copy @@ -1321,6 +1321,7 @@ SSL_F_TLS_PARSE_CTOS_RENEGOTIATE:464:tls_parse_ctos_renegotiate SSL_F_TLS_PARSE_CTOS_SERVER_NAME:573:tls_parse_ctos_server_name SSL_F_TLS_PARSE_CTOS_SESSION_TICKET:574:tls_parse_ctos_session_ticket SSL_F_TLS_PARSE_CTOS_SIG_ALGS:575:tls_parse_ctos_sig_algs +SSL_F_TLS_PARSE_CTOS_SIG_ALGS_CERT:615:tls_parse_ctos_sig_algs_cert SSL_F_TLS_PARSE_CTOS_SRP:576:tls_parse_ctos_srp SSL_F_TLS_PARSE_CTOS_STATUS_REQUEST:577:tls_parse_ctos_status_request SSL_F_TLS_PARSE_CTOS_SUPPORTED_GROUPS:578:tls_parse_ctos_supported_groups diff --git a/include/openssl/sslerr.h b/include/openssl/sslerr.h index 2431b492d1..ec81ba3f03 100644 --- a/include/openssl/sslerr.h +++ b/include/openssl/sslerr.h @@ -1,6 +1,6 @@ /* * Generated by util/mkerr.pl DO NOT EDIT - * Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved. + * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved. * * Licensed under the OpenSSL license (the "License"). You may not use * this file except in compliance with the License. You can obtain a copy @@ -364,6 +364,7 @@ int ERR_load_SSL_strings(void); # define SSL_F_TLS_PARSE_CTOS_SERVER_NAME 573 # define SSL_F_TLS_PARSE_CTOS_SESSION_TICKET 574 # define SSL_F_TLS_PARSE_CTOS_SIG_ALGS 575 +# define SSL_F_TLS_PARSE_CTOS_SIG_ALGS_CERT 615 # define SSL_F_TLS_PARSE_CTOS_SRP 576 # define SSL_F_TLS_PARSE_CTOS_STATUS_REQUEST 577 # define SSL_F_TLS_PARSE_CTOS_SUPPORTED_GROUPS 578 diff --git a/include/openssl/tls1.h b/include/openssl/tls1.h index 500a6374b9..434e327f76 100644 --- a/include/openssl/tls1.h +++ b/include/openssl/tls1.h @@ -146,6 +146,7 @@ extern "C" { # define TLSEXT_TYPE_cookie 44 # define TLSEXT_TYPE_psk_kex_modes 45 # define TLSEXT_TYPE_certificate_authorities 47 +# define TLSEXT_TYPE_signature_algorithms_cert 50 # define TLSEXT_TYPE_key_share 51 /* Temporary extension type */ diff --git a/ssl/s3_lib.c b/ssl/s3_lib.c index 9d8bd8b041..7efffd7fc0 100644 --- a/ssl/s3_lib.c +++ b/ssl/s3_lib.c @@ -3324,6 +3324,7 @@ void ssl3_free(SSL *s) OPENSSL_free(s->s3->tmp.ciphers_raw); OPENSSL_clear_free(s->s3->tmp.pms, s->s3->tmp.pmslen); OPENSSL_free(s->s3->tmp.peer_sigalgs); + OPENSSL_free(s->s3->tmp.peer_cert_sigalgs); ssl3_free_digest_list(s); OPENSSL_free(s->s3->alpn_selected); OPENSSL_free(s->s3->alpn_proposed); @@ -3343,6 +3344,7 @@ int ssl3_clear(SSL *s) OPENSSL_free(s->s3->tmp.ciphers_raw); OPENSSL_clear_free(s->s3->tmp.pms, s->s3->tmp.pmslen); OPENSSL_free(s->s3->tmp.peer_sigalgs); + OPENSSL_free(s->s3->tmp.peer_cert_sigalgs); #if !defined(OPENSSL_NO_EC) || !defined(OPENSSL_NO_DH) EVP_PKEY_free(s->s3->tmp.pkey); diff --git a/ssl/ssl_err.c b/ssl/ssl_err.c index 111579b3da..746678cb39 100644 --- a/ssl/ssl_err.c +++ b/ssl/ssl_err.c @@ -1,6 +1,6 @@ /* * Generated by util/mkerr.pl DO NOT EDIT - * Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved. + * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved. * * Licensed under the OpenSSL license (the "License"). You may not use * this file except in compliance with the License. You can obtain a copy @@ -568,6 +568,8 @@ static const ERR_STRING_DATA SSL_str_functs[] = { "tls_parse_ctos_session_ticket"}, {ERR_PACK(ERR_LIB_SSL, SSL_F_TLS_PARSE_CTOS_SIG_ALGS, 0), "tls_parse_ctos_sig_algs"}, + {ERR_PACK(ERR_LIB_SSL, SSL_F_TLS_PARSE_CTOS_SIG_ALGS_CERT, 0), + "tls_parse_ctos_sig_algs_cert"}, {ERR_PACK(ERR_LIB_SSL, SSL_F_TLS_PARSE_CTOS_SRP, 0), "tls_parse_ctos_srp"}, {ERR_PACK(ERR_LIB_SSL, SSL_F_TLS_PARSE_CTOS_STATUS_REQUEST, 0), "tls_parse_ctos_status_request"}, diff --git a/ssl/ssl_locl.h b/ssl/ssl_locl.h index 8d948fb479..6afd0091cf 100644 --- a/ssl/ssl_locl.h +++ b/ssl/ssl_locl.h @@ -701,6 +701,7 @@ typedef enum tlsext_index_en { TLSEXT_IDX_encrypt_then_mac, TLSEXT_IDX_signed_certificate_timestamp, TLSEXT_IDX_extended_master_secret, + TLSEXT_IDX_signature_algorithms_cert, TLSEXT_IDX_signature_algorithms, TLSEXT_IDX_supported_versions, TLSEXT_IDX_psk_kex_modes, @@ -1507,10 +1508,13 @@ typedef struct ssl3_state_st { * signature algorithms peer reports: e.g. supported signature * algorithms extension for server or as part of a certificate * request for client. + * Keep track of the algorithms for TLS and X.509 usage separately. */ uint16_t *peer_sigalgs; - /* Size of above array */ + uint16_t *peer_cert_sigalgs; + /* Size of above arrays */ size_t peer_sigalgslen; + size_t peer_cert_sigalgslen; /* Sigalg peer actually uses */ const SIGALG_LOOKUP *peer_sigalg; /* @@ -2473,7 +2477,7 @@ __owur long ssl_get_algorithm2(SSL *s); __owur int tls12_copy_sigalgs(SSL *s, WPACKET *pkt, const uint16_t *psig, size_t psiglen); __owur int tls1_save_u16(PACKET *pkt, uint16_t **pdest, size_t *pdestlen); -__owur int tls1_save_sigalgs(SSL *s, PACKET *pkt); +__owur int tls1_save_sigalgs(SSL *s, PACKET *pkt, int cert); __owur int tls1_process_sigalgs(SSL *s); __owur int tls1_set_peer_legacy_sigalg(SSL *s, const EVP_PKEY *pkey); __owur int tls1_lookup_md(const SIGALG_LOOKUP *lu, const EVP_MD **pmd); diff --git a/ssl/statem/extensions.c b/ssl/statem/extensions.c index 5a0fa25571..5ad86f20af 100644 --- a/ssl/statem/extensions.c +++ b/ssl/statem/extensions.c @@ -29,6 +29,7 @@ static int init_npn(SSL *s, unsigned int context); #endif static int init_alpn(SSL *s, unsigned int context); static int final_alpn(SSL *s, unsigned int context, int sent); +static int init_sig_algs_cert(SSL *s, unsigned int context); static int init_sig_algs(SSL *s, unsigned int context); static int init_certificate_authorities(SSL *s, unsigned int context); static EXT_RETURN tls_construct_certificate_authorities(SSL *s, WPACKET *pkt, @@ -280,6 +281,14 @@ static const EXTENSION_DEFINITION ext_defs[] = { init_ems, tls_parse_ctos_ems, tls_parse_stoc_ems, tls_construct_stoc_ems, tls_construct_ctos_ems, final_ems }, + { + TLSEXT_TYPE_signature_algorithms_cert, + SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_3_CERTIFICATE_REQUEST, + init_sig_algs_cert, tls_parse_ctos_sig_algs_cert, + tls_parse_ctos_sig_algs_cert, + /* We do not generate signature_algorithms_cert at present. */ + NULL, NULL, NULL + }, { TLSEXT_TYPE_signature_algorithms, SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_3_CERTIFICATE_REQUEST, @@ -1090,6 +1099,15 @@ static int init_sig_algs(SSL *s, unsigned int context) return 1; } +static int init_sig_algs_cert(SSL *s, unsigned int context) +{ + /* Clear any signature algorithms extension received */ + OPENSSL_free(s->s3->tmp.peer_cert_sigalgs); + s->s3->tmp.peer_cert_sigalgs = NULL; + + return 1; +} + #ifndef OPENSSL_NO_SRP static int init_srp(SSL *s, unsigned int context) { diff --git a/ssl/statem/extensions_srvr.c b/ssl/statem/extensions_srvr.c index fadc6a70ea..0a7bac4d8b 100644 --- a/ssl/statem/extensions_srvr.c +++ b/ssl/statem/extensions_srvr.c @@ -276,6 +276,27 @@ int tls_parse_ctos_session_ticket(SSL *s, PACKET *pkt, unsigned int context, return 1; } +int tls_parse_ctos_sig_algs_cert(SSL *s, PACKET *pkt, unsigned int context, + X509 *x, size_t chainidx) +{ + PACKET supported_sig_algs; + + if (!PACKET_as_length_prefixed_2(pkt, &supported_sig_algs) + || PACKET_remaining(&supported_sig_algs) == 0) { + SSLfatal(s, SSL_AD_DECODE_ERROR, + SSL_F_TLS_PARSE_CTOS_SIG_ALGS_CERT, SSL_R_BAD_EXTENSION); + return 0; + } + + if (!s->hit && !tls1_save_sigalgs(s, &supported_sig_algs, 1)) { + SSLfatal(s, SSL_AD_DECODE_ERROR, + SSL_F_TLS_PARSE_CTOS_SIG_ALGS_CERT, SSL_R_BAD_EXTENSION); + return 0; + } + + return 1; +} + int tls_parse_ctos_sig_algs(SSL *s, PACKET *pkt, unsigned int context, X509 *x, size_t chainidx) { @@ -288,7 +309,7 @@ int tls_parse_ctos_sig_algs(SSL *s, PACKET *pkt, unsigned int context, X509 *x, return 0; } - if (!s->hit && !tls1_save_sigalgs(s, &supported_sig_algs)) { + if (!s->hit && !tls1_save_sigalgs(s, &supported_sig_algs, 0)) { SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_CTOS_SIG_ALGS, SSL_R_BAD_EXTENSION); return 0; diff --git a/ssl/statem/statem_clnt.c b/ssl/statem/statem_clnt.c index 31291383fd..8a33386cd0 100644 --- a/ssl/statem/statem_clnt.c +++ b/ssl/statem/statem_clnt.c @@ -2458,7 +2458,11 @@ MSG_PROCESS_RETURN tls_process_certificate_request(SSL *s, PACKET *pkt) return MSG_PROCESS_ERROR; } - if (!tls1_save_sigalgs(s, &sigalgs)) { + /* + * Despite this being for certificates, preserve compatibility + * with pre-TLS 1.3 and use the regular sigalgs field. + */ + if (!tls1_save_sigalgs(s, &sigalgs, 0)) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PROCESS_CERTIFICATE_REQUEST, SSL_R_SIGNATURE_ALGORITHMS_ERROR); diff --git a/ssl/statem/statem_locl.h b/ssl/statem/statem_locl.h index 38b0ce8ba7..f16d3cba4e 100644 --- a/ssl/statem/statem_locl.h +++ b/ssl/statem/statem_locl.h @@ -205,6 +205,8 @@ int tls_parse_ctos_supported_groups(SSL *s, PACKET *pkt, unsigned int context, #endif int tls_parse_ctos_session_ticket(SSL *s, PACKET *pkt, unsigned int context, X509 *x, size_t chainidx); +int tls_parse_ctos_sig_algs_cert(SSL *s, PACKET *pkt, unsigned int context, + X509 *x, size_t chainidx); int tls_parse_ctos_sig_algs(SSL *s, PACKET *pkt, unsigned int context, X509 *x, size_t chainidx); #ifndef OPENSSL_NO_OCSP diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c index 00ac5133b3..d4c9086e5a 100644 --- a/ssl/t1_lib.c +++ b/ssl/t1_lib.c @@ -1131,7 +1131,8 @@ int tls1_set_server_sigalgs(SSL *s) * If peer sent no signature algorithms check to see if we support * the default algorithm for each certificate type */ - if (s->s3->tmp.peer_sigalgs == NULL) { + if (s->s3->tmp.peer_cert_sigalgs == NULL + && s->s3->tmp.peer_sigalgs == NULL) { const uint16_t *sent_sigs; size_t sent_sigslen = tls12_get_psigalgs(s, 1, &sent_sigs); @@ -1596,7 +1597,7 @@ int tls1_save_u16(PACKET *pkt, uint16_t **pdest, size_t *pdestlen) return 1; } -int tls1_save_sigalgs(SSL *s, PACKET *pkt) +int tls1_save_sigalgs(SSL *s, PACKET *pkt, int cert) { /* Extension ignored for inappropriate versions */ if (!SSL_USE_SIGALGS(s)) @@ -1605,10 +1606,13 @@ int tls1_save_sigalgs(SSL *s, PACKET *pkt) if (s->cert == NULL) return 0; - return tls1_save_u16(pkt, &s->s3->tmp.peer_sigalgs, - &s->s3->tmp.peer_sigalgslen); + if (cert) + return tls1_save_u16(pkt, &s->s3->tmp.peer_cert_sigalgs, + &s->s3->tmp.peer_cert_sigalgslen); + else + return tls1_save_u16(pkt, &s->s3->tmp.peer_sigalgs, + &s->s3->tmp.peer_sigalgslen); - return 1; } /* Set preferred digest for each key type */ @@ -1974,10 +1978,11 @@ int tls1_check_chain(SSL *s, X509 *x, EVP_PKEY *pk, STACK_OF(X509) *chain, if (TLS1_get_version(s) >= TLS1_2_VERSION && strict_mode) { int default_nid; int rsign = 0; - if (s->s3->tmp.peer_sigalgs) + if (s->s3->tmp.peer_cert_sigalgs != NULL + || s->s3->tmp.peer_sigalgs != NULL) { default_nid = 0; /* If no sigalgs extension use defaults from RFC5246 */ - else { + } else { switch (idx) { case SSL_PKEY_RSA: rsign = EVP_PKEY_RSA; @@ -2312,13 +2317,48 @@ static int tls12_get_cert_sigalg_idx(const SSL *s, const SIGALG_LOOKUP *lu) if (clu == NULL || !(clu->amask & s->s3->tmp.new_cipher->algorithm_auth)) return -1; - /* If PSS and we have no PSS cert use RSA */ - if (sig_idx == SSL_PKEY_RSA_PSS_SIGN && !ssl_has_cert(s, sig_idx)) - sig_idx = SSL_PKEY_RSA; - return s->s3->tmp.valid_flags[sig_idx] & CERT_PKEY_VALID ? sig_idx : -1; } +/* + * Returns true if |s| has a usable certificate configured for use + * with signature scheme |sig|. + * "Usable" includes a check for presence as well as applying + * the signature_algorithm_cert restrictions sent by the peer (if any). + * Returns false if no usable certificate is found. + */ +static int has_usable_cert(SSL *s, const SIGALG_LOOKUP *sig, int idx) +{ + const SIGALG_LOOKUP *lu; + int mdnid, pknid; + size_t i; + + /* TLS 1.2 callers can override lu->sig_idx, but not TLS 1.3 callers. */ + if (idx == -1) + idx = sig->sig_idx; + if (!ssl_has_cert(s, idx)) + return 0; + if (s->s3->tmp.peer_cert_sigalgs != NULL) { + for (i = 0; i < s->s3->tmp.peer_cert_sigalgslen; i++) { + lu = tls1_lookup_sigalg(s->s3->tmp.peer_cert_sigalgs[i]); + if (lu == NULL + || !X509_get_signature_info(s->cert->pkeys[idx].x509, &mdnid, + &pknid, NULL, NULL)) + continue; + /* + * TODO this does not differentiate between the + * rsa_pss_pss_* and rsa_pss_rsae_* schemes since we do not + * have a chain here that lets us look at the key OID in the + * signing certificate. + */ + if (mdnid == lu->hash && pknid == lu->sig) + return 1; + } + return 0; + } + return 1; +} + /* * Choose an appropriate signature algorithm based on available certificates * Sets chosen certificate and signature algorithm. @@ -2355,14 +2395,9 @@ int tls_choose_sigalg(SSL *s, int fatalerrs) || lu->sig == EVP_PKEY_DSA || lu->sig == EVP_PKEY_RSA) continue; - if (!tls1_lookup_md(lu, NULL)) + /* Check that we have a cert, and signature_algorithms_cert */ + if (!tls1_lookup_md(lu, NULL) || !has_usable_cert(s, lu, -1)) continue; - if (!ssl_has_cert(s, lu->sig_idx)) { - if (lu->sig_idx != SSL_PKEY_RSA_PSS_SIGN - || !ssl_has_cert(s, SSL_PKEY_RSA)) - continue; - sig_idx = SSL_PKEY_RSA; - } if (lu->sig == EVP_PKEY_EC) { #ifndef OPENSSL_NO_EC if (curve == -1) { @@ -2381,21 +2416,8 @@ int tls_choose_sigalg(SSL *s, int fatalerrs) } else if (lu->sig == EVP_PKEY_RSA_PSS) { /* validate that key is large enough for the signature algorithm */ EVP_PKEY *pkey; - int pkey_id; - if (sig_idx == -1) - pkey = s->cert->pkeys[lu->sig_idx].privatekey; - else - pkey = s->cert->pkeys[sig_idx].privatekey; - pkey_id = EVP_PKEY_id(pkey); - if (pkey_id != EVP_PKEY_RSA_PSS - && pkey_id != EVP_PKEY_RSA) - continue; - /* - * The pkey type is EVP_PKEY_RSA_PSS or EVP_PKEY_RSA - * EVP_PKEY_get0_RSA returns NULL if the type is not EVP_PKEY_RSA - * so use EVP_PKEY_get0 instead - */ + pkey = s->cert->pkeys[lu->sig_idx].privatekey; if (!rsa_pss_check_min_key_size(EVP_PKEY_get0(pkey), lu)) continue; } @@ -2416,8 +2438,8 @@ int tls_choose_sigalg(SSL *s, int fatalerrs) return 1; if (SSL_USE_SIGALGS(s)) { + size_t i; if (s->s3->tmp.peer_sigalgs != NULL) { - size_t i; #ifndef OPENSSL_NO_EC int curve; @@ -2444,21 +2466,16 @@ int tls_choose_sigalg(SSL *s, int fatalerrs) int cc_idx = s->cert->key - s->cert->pkeys; sig_idx = lu->sig_idx; - if (cc_idx != sig_idx) { - if (sig_idx != SSL_PKEY_RSA_PSS_SIGN - || cc_idx != SSL_PKEY_RSA) - continue; - sig_idx = SSL_PKEY_RSA; - } + if (cc_idx != sig_idx) + continue; } + /* Check that we have a cert, and sig_algs_cert */ + if (!has_usable_cert(s, lu, sig_idx)) + continue; if (lu->sig == EVP_PKEY_RSA_PSS) { /* validate that key is large enough for the signature algorithm */ EVP_PKEY *pkey = s->cert->pkeys[sig_idx].privatekey; - int pkey_id = EVP_PKEY_id(pkey); - if (pkey_id != EVP_PKEY_RSA_PSS - && pkey_id != EVP_PKEY_RSA) - continue; if (!rsa_pss_check_min_key_size(EVP_PKEY_get0(pkey), lu)) continue; } @@ -2479,7 +2496,7 @@ int tls_choose_sigalg(SSL *s, int fatalerrs) * If we have no sigalg use defaults */ const uint16_t *sent_sigs; - size_t sent_sigslen, i; + size_t sent_sigslen; if ((lu = tls1_get_legacy_sigalg(s, -1)) == NULL) { if (!fatalerrs) @@ -2492,7 +2509,8 @@ int tls_choose_sigalg(SSL *s, int fatalerrs) /* Check signature matches a type we sent */ sent_sigslen = tls12_get_psigalgs(s, 1, &sent_sigs); for (i = 0; i < sent_sigslen; i++, sent_sigs++) { - if (lu->sigalg == *sent_sigs) + if (lu->sigalg == *sent_sigs + && has_usable_cert(s, lu, lu->sig_idx)) break; } if (i == sent_sigslen) { -- 2.39.2