/* $OpenBSD: ssl_tlsext.c,v 1.149 2024/04/16 17:46:30 tb Exp $ */ /* * Copyright (c) 2016, 2017, 2019 Joel Sing * Copyright (c) 2017 Doug Hogan * Copyright (c) 2018-2019, 2024 Bob Beck * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #include #include #include #include #include #include #include "bytestring.h" #include "ssl_local.h" #include "ssl_sigalgs.h" #include "ssl_tlsext.h" #define TLSEXT_TYPE_alpn TLSEXT_TYPE_application_layer_protocol_negotiation #define TLSEXT_MAX_SUPPORTED_GROUPS 64 /* * Supported Application-Layer Protocol Negotiation - RFC 7301 */ static int tlsext_alpn_client_needs(SSL *s, uint16_t msg_type) { /* ALPN protos have been specified and this is the initial handshake */ return s->alpn_client_proto_list != NULL && s->s3->hs.finished_len == 0; } static int tlsext_alpn_client_build(SSL *s, uint16_t msg_type, CBB *cbb) { CBB protolist; if (!CBB_add_u16_length_prefixed(cbb, &protolist)) return 0; if (!CBB_add_bytes(&protolist, s->alpn_client_proto_list, s->alpn_client_proto_list_len)) return 0; if (!CBB_flush(cbb)) return 0; return 1; } int tlsext_alpn_check_format(CBS *cbs) { CBS proto_name_list; if (CBS_len(cbs) == 0) return 0; CBS_dup(cbs, &proto_name_list); while (CBS_len(&proto_name_list) > 0) { CBS proto_name; if (!CBS_get_u8_length_prefixed(&proto_name_list, &proto_name)) return 0; if (CBS_len(&proto_name) == 0) return 0; } return 1; } static int tlsext_alpn_server_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { CBS alpn, selected_cbs; const unsigned char *selected; unsigned char selected_len; int r; if (!CBS_get_u16_length_prefixed(cbs, &alpn)) return 0; if (!tlsext_alpn_check_format(&alpn)) return 0; if (s->ctx->alpn_select_cb == NULL) return 1; /* * XXX - A few things should be considered here: * 1. Ensure that the same protocol is selected on session resumption. * 2. Should the callback be called even if no ALPN extension was sent? * 3. TLSv1.2 and earlier: ensure that SNI has already been processed. */ r = s->ctx->alpn_select_cb(s, &selected, &selected_len, CBS_data(&alpn), CBS_len(&alpn), s->ctx->alpn_select_cb_arg); if (r == SSL_TLSEXT_ERR_OK) { CBS_init(&selected_cbs, selected, selected_len); if (!CBS_stow(&selected_cbs, &s->s3->alpn_selected, &s->s3->alpn_selected_len)) { *alert = SSL_AD_INTERNAL_ERROR; return 0; } return 1; } /* On SSL_TLSEXT_ERR_NOACK behave as if no callback was present. */ if (r == SSL_TLSEXT_ERR_NOACK) return 1; *alert = SSL_AD_NO_APPLICATION_PROTOCOL; SSLerror(s, SSL_R_NO_APPLICATION_PROTOCOL); return 0; } static int tlsext_alpn_server_needs(SSL *s, uint16_t msg_type) { return s->s3->alpn_selected != NULL; } static int tlsext_alpn_server_build(SSL *s, uint16_t msg_type, CBB *cbb) { CBB list, selected; if (!CBB_add_u16_length_prefixed(cbb, &list)) return 0; if (!CBB_add_u8_length_prefixed(&list, &selected)) return 0; if (!CBB_add_bytes(&selected, s->s3->alpn_selected, s->s3->alpn_selected_len)) return 0; if (!CBB_flush(cbb)) return 0; return 1; } static int tlsext_alpn_client_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { CBS list, proto; if (s->alpn_client_proto_list == NULL) { *alert = SSL_AD_UNSUPPORTED_EXTENSION; return 0; } if (!CBS_get_u16_length_prefixed(cbs, &list)) return 0; if (!CBS_get_u8_length_prefixed(&list, &proto)) return 0; if (CBS_len(&list) != 0) return 0; if (CBS_len(&proto) == 0) return 0; if (!CBS_stow(&proto, &s->s3->alpn_selected, &s->s3->alpn_selected_len)) return 0; return 1; } /* * Supported Groups - RFC 7919 section 2 */ static int tlsext_supportedgroups_client_needs(SSL *s, uint16_t msg_type) { return ssl_has_ecc_ciphers(s) || (s->s3->hs.our_max_tls_version >= TLS1_3_VERSION); } static int tlsext_supportedgroups_client_build(SSL *s, uint16_t msg_type, CBB *cbb) { const uint16_t *groups; size_t groups_len; CBB grouplist; int i; tls1_get_group_list(s, 0, &groups, &groups_len); if (groups_len == 0) { SSLerror(s, ERR_R_INTERNAL_ERROR); return 0; } if (!CBB_add_u16_length_prefixed(cbb, &grouplist)) return 0; for (i = 0; i < groups_len; i++) { if (!ssl_security_supported_group(s, groups[i])) continue; if (!CBB_add_u16(&grouplist, groups[i])) return 0; } if (!CBB_flush(cbb)) return 0; return 1; } static int tlsext_supportedgroups_server_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { uint16_t *groups = NULL; size_t groups_len; CBS grouplist; int i, j; int ret = 0; if (!CBS_get_u16_length_prefixed(cbs, &grouplist)) goto err; groups_len = CBS_len(&grouplist); if (groups_len == 0 || groups_len % 2 != 0) goto err; groups_len /= 2; if (groups_len > TLSEXT_MAX_SUPPORTED_GROUPS) goto err; if (s->hit) goto done; if (s->s3->hs.tls13.hrr) { if (s->session->tlsext_supportedgroups == NULL) { *alert = SSL_AD_HANDSHAKE_FAILURE; return 0; } /* * The ClientHello extension hashing ensures that the client * did not change its list of supported groups. */ goto done; } if (s->session->tlsext_supportedgroups != NULL) goto err; /* XXX internal error? */ if ((groups = reallocarray(NULL, groups_len, sizeof(uint16_t))) == NULL) { *alert = SSL_AD_INTERNAL_ERROR; goto err; } for (i = 0; i < groups_len; i++) { if (!CBS_get_u16(&grouplist, &groups[i])) goto err; /* * Do not allow duplicate groups to be sent. This is not * currently specified in RFC 8446 or earlier, but there is no * legitimate justification for this to occur in TLS 1.2 or TLS * 1.3. */ for (j = 0; j < i; j++) { if (groups[i] == groups[j]) { *alert = SSL_AD_ILLEGAL_PARAMETER; goto err; } } } if (CBS_len(&grouplist) != 0) goto err; s->session->tlsext_supportedgroups = groups; s->session->tlsext_supportedgroups_length = groups_len; groups = NULL; done: ret = 1; err: free(groups); return ret; } /* This extension is never used by the server. */ static int tlsext_supportedgroups_server_needs(SSL *s, uint16_t msg_type) { return 0; } static int tlsext_supportedgroups_server_build(SSL *s, uint16_t msg_type, CBB *cbb) { return 0; } static int tlsext_supportedgroups_client_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { /* * This extension is only allowed in TLSv1.3 encrypted extensions. * It is not permitted in a ServerHello in any version of TLS. */ if (msg_type != SSL_TLSEXT_MSG_EE) return 0; /* * RFC 8446, section 4.2.7: TLSv1.3 servers can send this extension but * clients must not act on it during the handshake. This allows servers * to advertise their preferences for subsequent handshakes. We ignore * this complication. */ if (!CBS_skip(cbs, CBS_len(cbs))) { *alert = SSL_AD_INTERNAL_ERROR; return 0; } return 1; } /* * Supported Point Formats Extension - RFC 4492 section 5.1.2 */ static int tlsext_ecpf_build(SSL *s, uint16_t msg_type, CBB *cbb) { CBB ecpf; size_t formats_len; const uint8_t *formats; tls1_get_formatlist(s, 0, &formats, &formats_len); if (formats_len == 0) { SSLerror(s, ERR_R_INTERNAL_ERROR); return 0; } if (!CBB_add_u8_length_prefixed(cbb, &ecpf)) return 0; if (!CBB_add_bytes(&ecpf, formats, formats_len)) return 0; if (!CBB_flush(cbb)) return 0; return 1; } static int tlsext_ecpf_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { CBS ecpf; if (!CBS_get_u8_length_prefixed(cbs, &ecpf)) return 0; if (CBS_len(&ecpf) == 0) return 0; /* Must contain uncompressed (0) - RFC 8422, section 5.1.2. */ if (!CBS_contains_zero_byte(&ecpf)) { SSLerror(s, SSL_R_TLS_INVALID_ECPOINTFORMAT_LIST); *alert = SSL_AD_ILLEGAL_PARAMETER; return 0; } if (!s->hit) { if (!CBS_stow(&ecpf, &(s->session->tlsext_ecpointformatlist), &(s->session->tlsext_ecpointformatlist_length))) { *alert = SSL_AD_INTERNAL_ERROR; return 0; } } return 1; } static int tlsext_ecpf_client_needs(SSL *s, uint16_t msg_type) { return ssl_has_ecc_ciphers(s); } static int tlsext_ecpf_client_build(SSL *s, uint16_t msg_type, CBB *cbb) { return tlsext_ecpf_build(s, msg_type, cbb); } static int tlsext_ecpf_server_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { return tlsext_ecpf_process(s, msg_type, cbs, alert); } static int tlsext_ecpf_server_needs(SSL *s, uint16_t msg_type) { return ssl_using_ecc_cipher(s); } static int tlsext_ecpf_server_build(SSL *s, uint16_t msg_type, CBB *cbb) { return tlsext_ecpf_build(s, msg_type, cbb); } static int tlsext_ecpf_client_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { return tlsext_ecpf_process(s, msg_type, cbs, alert); } /* * Renegotiation Indication - RFC 5746. */ static int tlsext_ri_client_needs(SSL *s, uint16_t msg_type) { return (s->renegotiate); } static int tlsext_ri_client_build(SSL *s, uint16_t msg_type, CBB *cbb) { CBB reneg; if (!CBB_add_u8_length_prefixed(cbb, &reneg)) return 0; if (!CBB_add_bytes(&reneg, s->s3->previous_client_finished, s->s3->previous_client_finished_len)) return 0; if (!CBB_flush(cbb)) return 0; return 1; } static int tlsext_ri_server_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { CBS reneg; if (!CBS_get_u8_length_prefixed(cbs, &reneg)) { SSLerror(s, SSL_R_RENEGOTIATION_ENCODING_ERR); return 0; } if (!CBS_mem_equal(&reneg, s->s3->previous_client_finished, s->s3->previous_client_finished_len)) { SSLerror(s, SSL_R_RENEGOTIATION_MISMATCH); *alert = SSL_AD_HANDSHAKE_FAILURE; return 0; } s->s3->renegotiate_seen = 1; s->s3->send_connection_binding = 1; return 1; } static int tlsext_ri_server_needs(SSL *s, uint16_t msg_type) { return (s->s3->hs.negotiated_tls_version < TLS1_3_VERSION && s->s3->send_connection_binding); } static int tlsext_ri_server_build(SSL *s, uint16_t msg_type, CBB *cbb) { CBB reneg; if (!CBB_add_u8_length_prefixed(cbb, &reneg)) return 0; if (!CBB_add_bytes(&reneg, s->s3->previous_client_finished, s->s3->previous_client_finished_len)) return 0; if (!CBB_add_bytes(&reneg, s->s3->previous_server_finished, s->s3->previous_server_finished_len)) return 0; if (!CBB_flush(cbb)) return 0; return 1; } static int tlsext_ri_client_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { CBS reneg, prev_client, prev_server; /* * Ensure that the previous client and server values are both not * present, or that they are both present. */ if ((s->s3->previous_client_finished_len == 0 && s->s3->previous_server_finished_len != 0) || (s->s3->previous_client_finished_len != 0 && s->s3->previous_server_finished_len == 0)) { *alert = SSL_AD_INTERNAL_ERROR; return 0; } if (!CBS_get_u8_length_prefixed(cbs, &reneg)) { SSLerror(s, SSL_R_RENEGOTIATION_ENCODING_ERR); return 0; } if (!CBS_get_bytes(&reneg, &prev_client, s->s3->previous_client_finished_len)) { SSLerror(s, SSL_R_RENEGOTIATION_ENCODING_ERR); return 0; } if (!CBS_get_bytes(&reneg, &prev_server, s->s3->previous_server_finished_len)) { SSLerror(s, SSL_R_RENEGOTIATION_ENCODING_ERR); return 0; } if (CBS_len(&reneg) != 0) { SSLerror(s, SSL_R_RENEGOTIATION_ENCODING_ERR); return 0; } if (!CBS_mem_equal(&prev_client, s->s3->previous_client_finished, s->s3->previous_client_finished_len)) { SSLerror(s, SSL_R_RENEGOTIATION_MISMATCH); *alert = SSL_AD_HANDSHAKE_FAILURE; return 0; } if (!CBS_mem_equal(&prev_server, s->s3->previous_server_finished, s->s3->previous_server_finished_len)) { SSLerror(s, SSL_R_RENEGOTIATION_MISMATCH); *alert = SSL_AD_HANDSHAKE_FAILURE; return 0; } s->s3->renegotiate_seen = 1; s->s3->send_connection_binding = 1; return 1; } /* * Signature Algorithms - RFC 5246 section 7.4.1.4.1. */ static int tlsext_sigalgs_client_needs(SSL *s, uint16_t msg_type) { return (s->s3->hs.our_max_tls_version >= TLS1_2_VERSION); } static int tlsext_sigalgs_client_build(SSL *s, uint16_t msg_type, CBB *cbb) { uint16_t tls_version = s->s3->hs.negotiated_tls_version; CBB sigalgs; if (msg_type == SSL_TLSEXT_MSG_CH) tls_version = s->s3->hs.our_min_tls_version; if (!CBB_add_u16_length_prefixed(cbb, &sigalgs)) return 0; if (!ssl_sigalgs_build(tls_version, &sigalgs, SSL_get_security_level(s))) return 0; if (!CBB_flush(cbb)) return 0; return 1; } static int tlsext_sigalgs_server_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { CBS sigalgs; if (!CBS_get_u16_length_prefixed(cbs, &sigalgs)) return 0; if (CBS_len(&sigalgs) % 2 != 0 || CBS_len(&sigalgs) > 64) return 0; if (!CBS_stow(&sigalgs, &s->s3->hs.sigalgs, &s->s3->hs.sigalgs_len)) return 0; return 1; } static int tlsext_sigalgs_server_needs(SSL *s, uint16_t msg_type) { return (s->s3->hs.negotiated_tls_version >= TLS1_3_VERSION); } static int tlsext_sigalgs_server_build(SSL *s, uint16_t msg_type, CBB *cbb) { CBB sigalgs; if (!CBB_add_u16_length_prefixed(cbb, &sigalgs)) return 0; if (!ssl_sigalgs_build(s->s3->hs.negotiated_tls_version, &sigalgs, SSL_get_security_level(s))) return 0; if (!CBB_flush(cbb)) return 0; return 1; } static int tlsext_sigalgs_client_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { CBS sigalgs; if (ssl_effective_tls_version(s) < TLS1_3_VERSION) return 0; if (!CBS_get_u16_length_prefixed(cbs, &sigalgs)) return 0; if (CBS_len(&sigalgs) % 2 != 0 || CBS_len(&sigalgs) > 64) return 0; if (!CBS_stow(&sigalgs, &s->s3->hs.sigalgs, &s->s3->hs.sigalgs_len)) return 0; return 1; } /* * Server Name Indication - RFC 6066, section 3. */ static int tlsext_sni_client_needs(SSL *s, uint16_t msg_type) { return (s->tlsext_hostname != NULL); } static int tlsext_sni_client_build(SSL *s, uint16_t msg_type, CBB *cbb) { CBB server_name_list, host_name; if (!CBB_add_u16_length_prefixed(cbb, &server_name_list)) return 0; if (!CBB_add_u8(&server_name_list, TLSEXT_NAMETYPE_host_name)) return 0; if (!CBB_add_u16_length_prefixed(&server_name_list, &host_name)) return 0; if (!CBB_add_bytes(&host_name, (const uint8_t *)s->tlsext_hostname, strlen(s->tlsext_hostname))) return 0; if (!CBB_flush(cbb)) return 0; return 1; } static int tlsext_sni_is_ip_literal(CBS *cbs, int *is_ip) { union { struct in_addr ip4; struct in6_addr ip6; } addrbuf; char *hostname = NULL; *is_ip = 0; if (!CBS_strdup(cbs, &hostname)) return 0; if (inet_pton(AF_INET, hostname, &addrbuf) == 1 || inet_pton(AF_INET6, hostname, &addrbuf) == 1) *is_ip = 1; free(hostname); return 1; } /* * Validate that the CBS contains only a hostname consisting of RFC 5890 * compliant A-labels (see RFC 6066 section 3). Not a complete check * since we don't parse punycode to verify its validity but limits to * correct structure and character set. */ int tlsext_sni_is_valid_hostname(CBS *cbs, int *is_ip) { uint8_t prev, c = 0; int component = 0; CBS hostname; *is_ip = 0; CBS_dup(cbs, &hostname); if (CBS_len(&hostname) > TLSEXT_MAXLEN_host_name) return 0; /* An IP literal is invalid as a host name (RFC 6066 section 3). */ if (!tlsext_sni_is_ip_literal(&hostname, is_ip)) return 0; if (*is_ip) return 0; while (CBS_len(&hostname) > 0) { prev = c; if (!CBS_get_u8(&hostname, &c)) return 0; /* Everything has to be ASCII, with no NUL byte. */ if (!isascii(c) || c == '\0') return 0; /* It must be alphanumeric, a '-', or a '.' */ if (!isalnum(c) && c != '-' && c != '.') return 0; /* '-' and '.' must not start a component or be at the end. */ if (component == 0 || CBS_len(&hostname) == 0) { if (c == '-' || c == '.') return 0; } if (c == '.') { /* Components can not end with a dash. */ if (prev == '-') return 0; /* Start new component */ component = 0; continue; } /* Components must be 63 chars or less. */ if (++component > 63) return 0; } return 1; } static int tlsext_sni_server_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { CBS server_name_list, host_name; uint8_t name_type; int is_ip; if (!CBS_get_u16_length_prefixed(cbs, &server_name_list)) goto err; if (!CBS_get_u8(&server_name_list, &name_type)) goto err; /* * RFC 6066 section 3, only one type (host_name) is specified. * We do not tolerate unknown types, neither does BoringSSL. * other implementations appear more tolerant. */ if (name_type != TLSEXT_NAMETYPE_host_name) { *alert = SSL_AD_ILLEGAL_PARAMETER; goto err; } /* * RFC 6066 section 3 specifies a host name must be at least 1 byte * so 0 length is a decode error. */ if (!CBS_get_u16_length_prefixed(&server_name_list, &host_name)) goto err; if (CBS_len(&host_name) < 1) goto err; if (!tlsext_sni_is_valid_hostname(&host_name, &is_ip)) { /* * Various pieces of software have been known to set the SNI * host name to an IP address, even though that violates the * RFC. If this is the case, pretend the SNI extension does * not exist. */ if (is_ip) goto done; *alert = SSL_AD_ILLEGAL_PARAMETER; goto err; } if (s->hit || s->s3->hs.tls13.hrr) { if (s->session->tlsext_hostname == NULL) { *alert = SSL_AD_UNRECOGNIZED_NAME; goto err; } if (!CBS_mem_equal(&host_name, s->session->tlsext_hostname, strlen(s->session->tlsext_hostname))) { *alert = SSL_AD_UNRECOGNIZED_NAME; goto err; } } else { if (s->session->tlsext_hostname != NULL) goto err; if (!CBS_strdup(&host_name, &s->session->tlsext_hostname)) { *alert = SSL_AD_INTERNAL_ERROR; goto err; } } done: /* * RFC 6066 section 3 forbids multiple host names with the same type, * therefore we allow only one entry. */ if (CBS_len(&server_name_list) != 0) { *alert = SSL_AD_ILLEGAL_PARAMETER; goto err; } return 1; err: return 0; } static int tlsext_sni_server_needs(SSL *s, uint16_t msg_type) { if (s->hit) return 0; return (s->session->tlsext_hostname != NULL); } static int tlsext_sni_server_build(SSL *s, uint16_t msg_type, CBB *cbb) { return 1; } static int tlsext_sni_client_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { if (s->tlsext_hostname == NULL || CBS_len(cbs) != 0) { *alert = SSL_AD_UNRECOGNIZED_NAME; return 0; } if (s->hit) { if (s->session->tlsext_hostname == NULL) { *alert = SSL_AD_UNRECOGNIZED_NAME; return 0; } if (strcmp(s->tlsext_hostname, s->session->tlsext_hostname) != 0) { *alert = SSL_AD_UNRECOGNIZED_NAME; return 0; } } else { if (s->session->tlsext_hostname != NULL) return 0; if ((s->session->tlsext_hostname = strdup(s->tlsext_hostname)) == NULL) { *alert = SSL_AD_INTERNAL_ERROR; return 0; } } return 1; } /* * Certificate Status Request - RFC 6066 section 8. */ static int tlsext_ocsp_client_needs(SSL *s, uint16_t msg_type) { if (msg_type != SSL_TLSEXT_MSG_CH) return 0; return (s->tlsext_status_type == TLSEXT_STATUSTYPE_ocsp); } static int tlsext_ocsp_client_build(SSL *s, uint16_t msg_type, CBB *cbb) { CBB respid_list, respid, exts; unsigned char *ext_data; size_t ext_len; int i; if (!CBB_add_u8(cbb, TLSEXT_STATUSTYPE_ocsp)) return 0; if (!CBB_add_u16_length_prefixed(cbb, &respid_list)) return 0; for (i = 0; i < sk_OCSP_RESPID_num(s->tlsext_ocsp_ids); i++) { unsigned char *respid_data; OCSP_RESPID *id; size_t id_len; if ((id = sk_OCSP_RESPID_value(s->tlsext_ocsp_ids, i)) == NULL) return 0; if ((id_len = i2d_OCSP_RESPID(id, NULL)) == -1) return 0; if (!CBB_add_u16_length_prefixed(&respid_list, &respid)) return 0; if (!CBB_add_space(&respid, &respid_data, id_len)) return 0; if ((i2d_OCSP_RESPID(id, &respid_data)) != id_len) return 0; } if (!CBB_add_u16_length_prefixed(cbb, &exts)) return 0; if ((ext_len = i2d_X509_EXTENSIONS(s->tlsext_ocsp_exts, NULL)) == -1) return 0; if (!CBB_add_space(&exts, &ext_data, ext_len)) return 0; if ((i2d_X509_EXTENSIONS(s->tlsext_ocsp_exts, &ext_data) != ext_len)) return 0; if (!CBB_flush(cbb)) return 0; return 1; } static int tlsext_ocsp_server_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { int alert_desc = SSL_AD_DECODE_ERROR; CBS respid_list, respid, exts; const unsigned char *p; uint8_t status_type; int ret = 0; if (msg_type != SSL_TLSEXT_MSG_CH) goto err; if (!CBS_get_u8(cbs, &status_type)) goto err; if (status_type != TLSEXT_STATUSTYPE_ocsp) { /* ignore unknown status types */ s->tlsext_status_type = -1; if (!CBS_skip(cbs, CBS_len(cbs))) { *alert = SSL_AD_INTERNAL_ERROR; return 0; } return 1; } s->tlsext_status_type = status_type; if (!CBS_get_u16_length_prefixed(cbs, &respid_list)) goto err; /* XXX */ sk_OCSP_RESPID_pop_free(s->tlsext_ocsp_ids, OCSP_RESPID_free); s->tlsext_ocsp_ids = NULL; if (CBS_len(&respid_list) > 0) { s->tlsext_ocsp_ids = sk_OCSP_RESPID_new_null(); if (s->tlsext_ocsp_ids == NULL) { alert_desc = SSL_AD_INTERNAL_ERROR; goto err; } } while (CBS_len(&respid_list) > 0) { OCSP_RESPID *id; if (!CBS_get_u16_length_prefixed(&respid_list, &respid)) goto err; p = CBS_data(&respid); if ((id = d2i_OCSP_RESPID(NULL, &p, CBS_len(&respid))) == NULL) goto err; if (!sk_OCSP_RESPID_push(s->tlsext_ocsp_ids, id)) { alert_desc = SSL_AD_INTERNAL_ERROR; OCSP_RESPID_free(id); goto err; } } /* Read in request_extensions */ if (!CBS_get_u16_length_prefixed(cbs, &exts)) goto err; if (CBS_len(&exts) > 0) { sk_X509_EXTENSION_pop_free(s->tlsext_ocsp_exts, X509_EXTENSION_free); p = CBS_data(&exts); if ((s->tlsext_ocsp_exts = d2i_X509_EXTENSIONS(NULL, &p, CBS_len(&exts))) == NULL) goto err; } ret = 1; err: if (ret == 0) *alert = alert_desc; return ret; } static int tlsext_ocsp_server_needs(SSL *s, uint16_t msg_type) { if (s->s3->hs.negotiated_tls_version >= TLS1_3_VERSION && s->tlsext_status_type == TLSEXT_STATUSTYPE_ocsp && s->ctx->tlsext_status_cb != NULL) { s->tlsext_status_expected = 0; if (s->ctx->tlsext_status_cb(s, s->ctx->tlsext_status_arg) == SSL_TLSEXT_ERR_OK && s->tlsext_ocsp_resp_len > 0) s->tlsext_status_expected = 1; } return s->tlsext_status_expected; } static int tlsext_ocsp_server_build(SSL *s, uint16_t msg_type, CBB *cbb) { CBB ocsp_response; if (s->s3->hs.negotiated_tls_version >= TLS1_3_VERSION) { if (!CBB_add_u8(cbb, TLSEXT_STATUSTYPE_ocsp)) return 0; if (!CBB_add_u24_length_prefixed(cbb, &ocsp_response)) return 0; if (!CBB_add_bytes(&ocsp_response, s->tlsext_ocsp_resp, s->tlsext_ocsp_resp_len)) return 0; if (!CBB_flush(cbb)) return 0; } return 1; } static int tlsext_ocsp_client_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { uint8_t status_type; CBS response; if (ssl_effective_tls_version(s) >= TLS1_3_VERSION) { if (msg_type == SSL_TLSEXT_MSG_CR) { /* * RFC 8446, 4.4.2.1 - the server may request an OCSP * response with an empty status_request. */ if (CBS_len(cbs) == 0) return 1; SSLerror(s, SSL_R_LENGTH_MISMATCH); return 0; } if (!CBS_get_u8(cbs, &status_type)) { SSLerror(s, SSL_R_LENGTH_MISMATCH); return 0; } if (status_type != TLSEXT_STATUSTYPE_ocsp) { SSLerror(s, SSL_R_UNSUPPORTED_STATUS_TYPE); return 0; } if (!CBS_get_u24_length_prefixed(cbs, &response)) { SSLerror(s, SSL_R_LENGTH_MISMATCH); return 0; } if (CBS_len(&response) > 65536) { SSLerror(s, SSL_R_DATA_LENGTH_TOO_LONG); return 0; } if (!CBS_stow(&response, &s->tlsext_ocsp_resp, &s->tlsext_ocsp_resp_len)) { *alert = SSL_AD_INTERNAL_ERROR; return 0; } } else { if (s->tlsext_status_type == -1) { *alert = SSL_AD_UNSUPPORTED_EXTENSION; return 0; } /* Set flag to expect CertificateStatus message */ s->tlsext_status_expected = 1; } return 1; } /* * SessionTicket extension - RFC 5077 section 3.2 */ static int tlsext_sessionticket_client_needs(SSL *s, uint16_t msg_type) { /* * Send session ticket extension when enabled and not overridden. * * When renegotiating, send an empty session ticket to indicate support. */ if ((SSL_get_options(s) & SSL_OP_NO_TICKET) != 0) return 0; if (!ssl_security_tickets(s)) return 0; if (s->new_session) return 1; if (s->tlsext_session_ticket != NULL && s->tlsext_session_ticket->data == NULL) return 0; return 1; } static int tlsext_sessionticket_client_build(SSL *s, uint16_t msg_type, CBB *cbb) { /* * Signal that we support session tickets by sending an empty * extension when renegotiating or no session found. */ if (s->new_session || s->session == NULL) return 1; if (s->session->tlsext_tick != NULL) { /* Attempt to resume with an existing session ticket */ if (!CBB_add_bytes(cbb, s->session->tlsext_tick, s->session->tlsext_ticklen)) return 0; } else if (s->tlsext_session_ticket != NULL) { /* * Attempt to resume with a custom provided session ticket set * by SSL_set_session_ticket_ext(). */ if (s->tlsext_session_ticket->length > 0) { size_t ticklen = s->tlsext_session_ticket->length; if ((s->session->tlsext_tick = malloc(ticklen)) == NULL) return 0; memcpy(s->session->tlsext_tick, s->tlsext_session_ticket->data, ticklen); s->session->tlsext_ticklen = ticklen; if (!CBB_add_bytes(cbb, s->session->tlsext_tick, s->session->tlsext_ticklen)) return 0; } } if (!CBB_flush(cbb)) return 0; return 1; } static int tlsext_sessionticket_server_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { if (s->tls_session_ticket_ext_cb) { if (!s->tls_session_ticket_ext_cb(s, CBS_data(cbs), (int)CBS_len(cbs), s->tls_session_ticket_ext_cb_arg)) { *alert = SSL_AD_INTERNAL_ERROR; return 0; } } /* We need to signal that this was processed fully */ if (!CBS_skip(cbs, CBS_len(cbs))) { *alert = SSL_AD_INTERNAL_ERROR; return 0; } return 1; } static int tlsext_sessionticket_server_needs(SSL *s, uint16_t msg_type) { return (s->tlsext_ticket_expected && !(SSL_get_options(s) & SSL_OP_NO_TICKET) && ssl_security_tickets(s)); } static int tlsext_sessionticket_server_build(SSL *s, uint16_t msg_type, CBB *cbb) { /* Empty ticket */ return 1; } static int tlsext_sessionticket_client_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { if (s->tls_session_ticket_ext_cb) { if (!s->tls_session_ticket_ext_cb(s, CBS_data(cbs), (int)CBS_len(cbs), s->tls_session_ticket_ext_cb_arg)) { *alert = SSL_AD_INTERNAL_ERROR; return 0; } } if ((SSL_get_options(s) & SSL_OP_NO_TICKET) != 0 || CBS_len(cbs) > 0) { *alert = SSL_AD_UNSUPPORTED_EXTENSION; return 0; } s->tlsext_ticket_expected = 1; return 1; } /* * DTLS extension for SRTP key establishment - RFC 5764 */ #ifndef OPENSSL_NO_SRTP static int tlsext_srtp_client_needs(SSL *s, uint16_t msg_type) { return SSL_is_dtls(s) && SSL_get_srtp_profiles(s) != NULL; } static int tlsext_srtp_client_build(SSL *s, uint16_t msg_type, CBB *cbb) { CBB profiles, mki; int ct, i; STACK_OF(SRTP_PROTECTION_PROFILE) *clnt = NULL; const SRTP_PROTECTION_PROFILE *prof; if ((clnt = SSL_get_srtp_profiles(s)) == NULL) { SSLerror(s, SSL_R_EMPTY_SRTP_PROTECTION_PROFILE_LIST); return 0; } if ((ct = sk_SRTP_PROTECTION_PROFILE_num(clnt)) < 1) { SSLerror(s, SSL_R_EMPTY_SRTP_PROTECTION_PROFILE_LIST); return 0; } if (!CBB_add_u16_length_prefixed(cbb, &profiles)) return 0; for (i = 0; i < ct; i++) { if ((prof = sk_SRTP_PROTECTION_PROFILE_value(clnt, i)) == NULL) return 0; if (!CBB_add_u16(&profiles, prof->id)) return 0; } if (!CBB_add_u8_length_prefixed(cbb, &mki)) return 0; if (!CBB_flush(cbb)) return 0; return 1; } static int tlsext_srtp_server_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { const SRTP_PROTECTION_PROFILE *cprof, *sprof; STACK_OF(SRTP_PROTECTION_PROFILE) *clnt = NULL, *srvr; int i, j; int ret; uint16_t id; CBS profiles, mki; ret = 0; if (!CBS_get_u16_length_prefixed(cbs, &profiles)) goto err; if (CBS_len(&profiles) == 0 || CBS_len(&profiles) % 2 != 0) goto err; if ((clnt = sk_SRTP_PROTECTION_PROFILE_new_null()) == NULL) goto err; while (CBS_len(&profiles) > 0) { if (!CBS_get_u16(&profiles, &id)) goto err; if (!srtp_find_profile_by_num(id, &cprof)) { if (!sk_SRTP_PROTECTION_PROFILE_push(clnt, cprof)) goto err; } } if (!CBS_get_u8_length_prefixed(cbs, &mki) || CBS_len(&mki) != 0) { SSLerror(s, SSL_R_BAD_SRTP_MKI_VALUE); goto done; } /* * Per RFC 5764 section 4.1.1 * * Find the server preferred profile using the client's list. * * The server MUST send a profile if it sends the use_srtp * extension. If one is not found, it should fall back to the * negotiated DTLS cipher suite or return a DTLS alert. */ if ((srvr = SSL_get_srtp_profiles(s)) == NULL) goto err; for (i = 0; i < sk_SRTP_PROTECTION_PROFILE_num(srvr); i++) { if ((sprof = sk_SRTP_PROTECTION_PROFILE_value(srvr, i)) == NULL) goto err; for (j = 0; j < sk_SRTP_PROTECTION_PROFILE_num(clnt); j++) { if ((cprof = sk_SRTP_PROTECTION_PROFILE_value(clnt, j)) == NULL) goto err; if (cprof->id == sprof->id) { s->srtp_profile = sprof; ret = 1; goto done; } } } /* If we didn't find anything, fall back to the negotiated */ ret = 1; goto done; err: SSLerror(s, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST); done: sk_SRTP_PROTECTION_PROFILE_free(clnt); return ret; } static int tlsext_srtp_server_needs(SSL *s, uint16_t msg_type) { return SSL_is_dtls(s) && SSL_get_selected_srtp_profile(s) != NULL; } static int tlsext_srtp_server_build(SSL *s, uint16_t msg_type, CBB *cbb) { SRTP_PROTECTION_PROFILE *profile; CBB srtp, mki; if (!CBB_add_u16_length_prefixed(cbb, &srtp)) return 0; if ((profile = SSL_get_selected_srtp_profile(s)) == NULL) return 0; if (!CBB_add_u16(&srtp, profile->id)) return 0; if (!CBB_add_u8_length_prefixed(cbb, &mki)) return 0; if (!CBB_flush(cbb)) return 0; return 1; } static int tlsext_srtp_client_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { STACK_OF(SRTP_PROTECTION_PROFILE) *clnt; const SRTP_PROTECTION_PROFILE *prof; int i; uint16_t id; CBS profile_ids, mki; if (!CBS_get_u16_length_prefixed(cbs, &profile_ids)) { SSLerror(s, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST); return 0; } if (!CBS_get_u16(&profile_ids, &id) || CBS_len(&profile_ids) != 0) { SSLerror(s, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST); return 0; } if (!CBS_get_u8_length_prefixed(cbs, &mki) || CBS_len(&mki) != 0) { SSLerror(s, SSL_R_BAD_SRTP_MKI_VALUE); *alert = SSL_AD_ILLEGAL_PARAMETER; return 0; } if ((clnt = SSL_get_srtp_profiles(s)) == NULL) { SSLerror(s, SSL_R_NO_SRTP_PROFILES); return 0; } for (i = 0; i < sk_SRTP_PROTECTION_PROFILE_num(clnt); i++) { if ((prof = sk_SRTP_PROTECTION_PROFILE_value(clnt, i)) == NULL) { SSLerror(s, SSL_R_NO_SRTP_PROFILES); return 0; } if (prof->id == id) { s->srtp_profile = prof; return 1; } } SSLerror(s, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST); return 0; } #endif /* OPENSSL_NO_SRTP */ /* * TLSv1.3 Key Share - RFC 8446 section 4.2.8. */ static int tlsext_keyshare_client_needs(SSL *s, uint16_t msg_type) { return (s->s3->hs.our_max_tls_version >= TLS1_3_VERSION); } static int tlsext_keyshare_client_build(SSL *s, uint16_t msg_type, CBB *cbb) { CBB client_shares, key_exchange; if (!CBB_add_u16_length_prefixed(cbb, &client_shares)) return 0; if (!CBB_add_u16(&client_shares, tls_key_share_group(s->s3->hs.key_share))) return 0; if (!CBB_add_u16_length_prefixed(&client_shares, &key_exchange)) return 0; if (!tls_key_share_public(s->s3->hs.key_share, &key_exchange)) return 0; if (!CBB_flush(cbb)) return 0; return 1; } static int tlsext_keyshare_server_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { const uint16_t *client_groups = NULL, *server_groups = NULL; size_t client_groups_len = 0, server_groups_len = 0; size_t i, j, client_groups_index; int preferred_group_found = 0; int decode_error; uint16_t group, client_preferred_group; CBS client_shares, key_exchange; /* * RFC 8446 section 4.2.8: * * Each KeyShareEntry value MUST correspond to a group offered in the * "supported_groups" extension and MUST appear in the same order. * However, the values MAY be a non-contiguous subset of the * "supported_groups". */ if (!tlsext_extension_seen(s, TLSEXT_TYPE_supported_groups)) { *alert = SSL_AD_ILLEGAL_PARAMETER; return 0; } if (!tlsext_extension_processed(s, TLSEXT_TYPE_supported_groups)) { *alert = SSL_AD_INTERNAL_ERROR; return 0; } if (s->s3->hs.tls13.hrr) { if (!CBS_get_u16_length_prefixed(cbs, &client_shares)) return 0; /* Unpack client share. */ if (!CBS_get_u16(&client_shares, &group)) return 0; if (!CBS_get_u16_length_prefixed(&client_shares, &key_exchange)) return 0; /* There should only be one share. */ if (CBS_len(&client_shares) != 0) return 0; if (group != s->s3->hs.tls13.server_group) { *alert = SSL_AD_ILLEGAL_PARAMETER; return 0; } if (s->s3->hs.key_share != NULL) { *alert = SSL_AD_INTERNAL_ERROR; return 0; } /* Decode and store the selected key share. */ if ((s->s3->hs.key_share = tls_key_share_new(group)) == NULL) { *alert = SSL_AD_INTERNAL_ERROR; return 0; } if (!tls_key_share_peer_public(s->s3->hs.key_share, &key_exchange, &decode_error, NULL)) { if (!decode_error) *alert = SSL_AD_INTERNAL_ERROR; return 0; } return 1; } /* * XXX similar to tls1_get_supported_group, but client pref * only - consider deduping later. */ /* * We are now assured of at least one client group. * Get the client and server group preference orders. */ tls1_get_group_list(s, 0, &server_groups, &server_groups_len); tls1_get_group_list(s, 1, &client_groups, &client_groups_len); /* * Find the group that is most preferred by the client that * we also support. */ for (i = 0; i < client_groups_len && !preferred_group_found; i++) { if (!ssl_security_supported_group(s, client_groups[i])) continue; for (j = 0; j < server_groups_len; j++) { if (server_groups[j] == client_groups[i]) { client_preferred_group = client_groups[i]; preferred_group_found = 1; break; } } } if (!CBS_get_u16_length_prefixed(cbs, &client_shares)) return 0; client_groups_index = 0; while (CBS_len(&client_shares) > 0) { int client_sent_group; /* Unpack client share. */ if (!CBS_get_u16(&client_shares, &group)) return 0; if (!CBS_get_u16_length_prefixed(&client_shares, &key_exchange)) return 0; /* * Ensure the client share group was sent in supported groups, * and was sent in the same order as supported groups. The * supported groups has already been checked for duplicates. */ client_sent_group = 0; while (client_groups_index < client_groups_len) { if (group == client_groups[client_groups_index++]) { client_sent_group = 1; break; } } if (!client_sent_group) { *alert = SSL_AD_ILLEGAL_PARAMETER; return 0; } /* * Ignore this client share if we're using earlier than TLSv1.3 * or we've already selected a key share. */ if (s->s3->hs.our_max_tls_version < TLS1_3_VERSION) continue; if (s->s3->hs.key_share != NULL) continue; /* * Ignore this client share if it is not for the most client * preferred supported group. This avoids a potential downgrade * situation where the client sends a client share for something * less preferred, and we choose to to use it instead of * requesting the more preferred group. */ if (!preferred_group_found || group != client_preferred_group) continue; /* Decode and store the selected key share. */ if ((s->s3->hs.key_share = tls_key_share_new(group)) == NULL) { *alert = SSL_AD_INTERNAL_ERROR; return 0; } if (!tls_key_share_peer_public(s->s3->hs.key_share, &key_exchange, &decode_error, NULL)) { if (!decode_error) *alert = SSL_AD_INTERNAL_ERROR; return 0; } } return 1; } static int tlsext_keyshare_server_needs(SSL *s, uint16_t msg_type) { return (s->s3->hs.negotiated_tls_version >= TLS1_3_VERSION && tlsext_extension_seen(s, TLSEXT_TYPE_key_share)); } static int tlsext_keyshare_server_build(SSL *s, uint16_t msg_type, CBB *cbb) { CBB key_exchange; /* In the case of a HRR, we only send the server selected group. */ if (s->s3->hs.tls13.hrr) { if (s->s3->hs.tls13.server_group == 0) return 0; return CBB_add_u16(cbb, s->s3->hs.tls13.server_group); } if (s->s3->hs.key_share == NULL) return 0; if (!CBB_add_u16(cbb, tls_key_share_group(s->s3->hs.key_share))) return 0; if (!CBB_add_u16_length_prefixed(cbb, &key_exchange)) return 0; if (!tls_key_share_public(s->s3->hs.key_share, &key_exchange)) return 0; if (!CBB_flush(cbb)) return 0; return 1; } static int tlsext_keyshare_client_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { CBS key_exchange; int decode_error; uint16_t group; /* Unpack server share. */ if (!CBS_get_u16(cbs, &group)) return 0; if (CBS_len(cbs) == 0) { /* HRR does not include an actual key share, only the group. */ if (msg_type != SSL_TLSEXT_MSG_HRR) return 0; s->s3->hs.tls13.server_group = group; return 1; } if (!CBS_get_u16_length_prefixed(cbs, &key_exchange)) return 0; if (s->s3->hs.key_share == NULL) { *alert = SSL_AD_INTERNAL_ERROR; return 0; } if (tls_key_share_group(s->s3->hs.key_share) != group) { *alert = SSL_AD_INTERNAL_ERROR; return 0; } if (!tls_key_share_peer_public(s->s3->hs.key_share, &key_exchange, &decode_error, NULL)) { if (!decode_error) *alert = SSL_AD_INTERNAL_ERROR; return 0; } return 1; } /* * Supported Versions - RFC 8446 section 4.2.1. */ static int tlsext_versions_client_needs(SSL *s, uint16_t msg_type) { return (s->s3->hs.our_max_tls_version >= TLS1_3_VERSION); } static int tlsext_versions_client_build(SSL *s, uint16_t msg_type, CBB *cbb) { uint16_t max, min; uint16_t version; CBB versions; max = s->s3->hs.our_max_tls_version; min = s->s3->hs.our_min_tls_version; if (!CBB_add_u8_length_prefixed(cbb, &versions)) return 0; /* XXX - fix, but contiguous for now... */ for (version = max; version >= min; version--) { if (!CBB_add_u16(&versions, version)) return 0; } if (!CBB_flush(cbb)) return 0; return 1; } static int tlsext_versions_server_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { CBS versions; uint16_t version; uint16_t max, min; uint16_t matched_version = 0; max = s->s3->hs.our_max_tls_version; min = s->s3->hs.our_min_tls_version; if (!CBS_get_u8_length_prefixed(cbs, &versions)) return 0; while (CBS_len(&versions) > 0) { if (!CBS_get_u16(&versions, &version)) return 0; /* * XXX What is below implements client preference, and * ignores any server preference entirely. */ if (matched_version == 0 && version >= min && version <= max) matched_version = version; } if (matched_version > 0) { /* XXX - this should be stored for later processing. */ s->version = matched_version; return 1; } *alert = SSL_AD_PROTOCOL_VERSION; return 0; } static int tlsext_versions_server_needs(SSL *s, uint16_t msg_type) { return (s->s3->hs.negotiated_tls_version >= TLS1_3_VERSION); } static int tlsext_versions_server_build(SSL *s, uint16_t msg_type, CBB *cbb) { return CBB_add_u16(cbb, TLS1_3_VERSION); } static int tlsext_versions_client_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { uint16_t selected_version; if (!CBS_get_u16(cbs, &selected_version)) return 0; /* XXX - need to fix for DTLS 1.3 */ if (selected_version < TLS1_3_VERSION) { *alert = SSL_AD_ILLEGAL_PARAMETER; return 0; } /* XXX test between min and max once initialization code goes in */ s->s3->hs.tls13.server_version = selected_version; return 1; } /* * Cookie - RFC 8446 section 4.2.2. */ static int tlsext_cookie_client_needs(SSL *s, uint16_t msg_type) { return (s->s3->hs.our_max_tls_version >= TLS1_3_VERSION && s->s3->hs.tls13.cookie_len > 0 && s->s3->hs.tls13.cookie != NULL); } static int tlsext_cookie_client_build(SSL *s, uint16_t msg_type, CBB *cbb) { CBB cookie; if (!CBB_add_u16_length_prefixed(cbb, &cookie)) return 0; if (!CBB_add_bytes(&cookie, s->s3->hs.tls13.cookie, s->s3->hs.tls13.cookie_len)) return 0; if (!CBB_flush(cbb)) return 0; return 1; } static int tlsext_cookie_server_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { CBS cookie; if (!CBS_get_u16_length_prefixed(cbs, &cookie)) return 0; if (CBS_len(&cookie) != s->s3->hs.tls13.cookie_len) return 0; /* * Check provided cookie value against what server previously * sent - client *MUST* send the same cookie with new CR after * a cookie is sent by the server with an HRR. */ if (!CBS_mem_equal(&cookie, s->s3->hs.tls13.cookie, s->s3->hs.tls13.cookie_len)) { /* XXX special cookie mismatch alert? */ *alert = SSL_AD_ILLEGAL_PARAMETER; return 0; } return 1; } static int tlsext_cookie_server_needs(SSL *s, uint16_t msg_type) { /* * Server needs to set cookie value in tls13 handshake * in order to send one, should only be sent with HRR. */ return (s->s3->hs.our_max_tls_version >= TLS1_3_VERSION && s->s3->hs.tls13.cookie_len > 0 && s->s3->hs.tls13.cookie != NULL); } static int tlsext_cookie_server_build(SSL *s, uint16_t msg_type, CBB *cbb) { CBB cookie; /* XXX deduplicate with client code */ if (!CBB_add_u16_length_prefixed(cbb, &cookie)) return 0; if (!CBB_add_bytes(&cookie, s->s3->hs.tls13.cookie, s->s3->hs.tls13.cookie_len)) return 0; if (!CBB_flush(cbb)) return 0; return 1; } static int tlsext_cookie_client_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { CBS cookie; /* * XXX This currently assumes we will not get a second * HRR from a server with a cookie to process after accepting * one from the server in the same handshake */ if (s->s3->hs.tls13.cookie != NULL || s->s3->hs.tls13.cookie_len != 0) { *alert = SSL_AD_ILLEGAL_PARAMETER; return 0; } if (!CBS_get_u16_length_prefixed(cbs, &cookie)) return 0; if (!CBS_stow(&cookie, &s->s3->hs.tls13.cookie, &s->s3->hs.tls13.cookie_len)) return 0; return 1; } /* * Pre-Shared Key Exchange Modes - RFC 8446, 4.2.9. */ static int tlsext_psk_kex_modes_client_needs(SSL *s, uint16_t msg_type) { return (s->s3->hs.tls13.use_psk_dhe_ke && s->s3->hs.our_max_tls_version >= TLS1_3_VERSION); } static int tlsext_psk_kex_modes_client_build(SSL *s, uint16_t msg_type, CBB *cbb) { CBB ke_modes; if (!CBB_add_u8_length_prefixed(cbb, &ke_modes)) return 0; /* Only indicate support for PSK with DHE key establishment. */ if (!CBB_add_u8(&ke_modes, TLS13_PSK_DHE_KE)) return 0; if (!CBB_flush(cbb)) return 0; return 1; } static int tlsext_psk_kex_modes_server_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { CBS ke_modes; uint8_t ke_mode; if (!CBS_get_u8_length_prefixed(cbs, &ke_modes)) return 0; while (CBS_len(&ke_modes) > 0) { if (!CBS_get_u8(&ke_modes, &ke_mode)) return 0; if (ke_mode == TLS13_PSK_DHE_KE) s->s3->hs.tls13.use_psk_dhe_ke = 1; } return 1; } static int tlsext_psk_kex_modes_server_needs(SSL *s, uint16_t msg_type) { /* Servers MUST NOT send this extension. */ return 0; } static int tlsext_psk_kex_modes_server_build(SSL *s, uint16_t msg_type, CBB *cbb) { return 0; } static int tlsext_psk_kex_modes_client_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { return 0; } /* * Pre-Shared Key Extension - RFC 8446, 4.2.11 */ static int tlsext_psk_client_needs(SSL *s, uint16_t msg_type) { return 0; } static int tlsext_psk_client_build(SSL *s, uint16_t msg_type, CBB *cbb) { return 0; } static int tlsext_psk_client_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { return CBS_skip(cbs, CBS_len(cbs)); } static int tlsext_psk_server_needs(SSL *s, uint16_t msg_type) { return 0; } static int tlsext_psk_server_build(SSL *s, uint16_t msg_type, CBB *cbb) { return 0; } static int tlsext_psk_server_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { return CBS_skip(cbs, CBS_len(cbs)); } /* * QUIC transport parameters extension - RFC 9001 section 8.2. */ static int tlsext_quic_transport_parameters_client_needs(SSL *s, uint16_t msg_type) { return SSL_is_quic(s) && s->quic_transport_params_len > 0; } static int tlsext_quic_transport_parameters_client_build(SSL *s, uint16_t msg_type, CBB *cbb) { if (!CBB_add_bytes(cbb, s->quic_transport_params, s->quic_transport_params_len)) return 0; return 1; } static int tlsext_quic_transport_parameters_client_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { if (!SSL_is_quic(s)) { *alert = SSL_AD_UNSUPPORTED_EXTENSION; return 0; } if (!CBS_stow(cbs, &s->s3->peer_quic_transport_params, &s->s3->peer_quic_transport_params_len)) return 0; if (!CBS_skip(cbs, s->s3->peer_quic_transport_params_len)) return 0; return 1; } static int tlsext_quic_transport_parameters_server_needs(SSL *s, uint16_t msg_type) { return SSL_is_quic(s) && s->quic_transport_params_len > 0; } static int tlsext_quic_transport_parameters_server_build(SSL *s, uint16_t msg_type, CBB *cbb) { if (!CBB_add_bytes(cbb, s->quic_transport_params, s->quic_transport_params_len)) return 0; return 1; } static int tlsext_quic_transport_parameters_server_process(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { if (!SSL_is_quic(s)) { *alert = SSL_AD_UNSUPPORTED_EXTENSION; return 0; } if (!CBS_stow(cbs, &s->s3->peer_quic_transport_params, &s->s3->peer_quic_transport_params_len)) return 0; if (!CBS_skip(cbs, s->s3->peer_quic_transport_params_len)) return 0; return 1; } struct tls_extension_funcs { int (*needs)(SSL *s, uint16_t msg_type); int (*build)(SSL *s, uint16_t msg_type, CBB *cbb); int (*process)(SSL *s, uint16_t msg_type, CBS *cbs, int *alert); }; struct tls_extension { uint16_t type; uint16_t messages; struct tls_extension_funcs client; struct tls_extension_funcs server; }; /* * TLS extensions (in processing order). */ static const struct tls_extension tls_extensions[] = { { .type = TLSEXT_TYPE_supported_versions, .messages = SSL_TLSEXT_MSG_CH | SSL_TLSEXT_MSG_SH | SSL_TLSEXT_MSG_HRR, .client = { .needs = tlsext_versions_client_needs, .build = tlsext_versions_client_build, .process = tlsext_versions_client_process, }, .server = { .needs = tlsext_versions_server_needs, .build = tlsext_versions_server_build, .process = tlsext_versions_server_process, }, }, { .type = TLSEXT_TYPE_supported_groups, .messages = SSL_TLSEXT_MSG_CH | SSL_TLSEXT_MSG_EE, .client = { .needs = tlsext_supportedgroups_client_needs, .build = tlsext_supportedgroups_client_build, .process = tlsext_supportedgroups_client_process, }, .server = { .needs = tlsext_supportedgroups_server_needs, .build = tlsext_supportedgroups_server_build, .process = tlsext_supportedgroups_server_process, }, }, { .type = TLSEXT_TYPE_key_share, .messages = SSL_TLSEXT_MSG_CH | SSL_TLSEXT_MSG_SH | SSL_TLSEXT_MSG_HRR, .client = { .needs = tlsext_keyshare_client_needs, .build = tlsext_keyshare_client_build, .process = tlsext_keyshare_client_process, }, .server = { .needs = tlsext_keyshare_server_needs, .build = tlsext_keyshare_server_build, .process = tlsext_keyshare_server_process, }, }, { .type = TLSEXT_TYPE_server_name, .messages = SSL_TLSEXT_MSG_CH | SSL_TLSEXT_MSG_EE, .client = { .needs = tlsext_sni_client_needs, .build = tlsext_sni_client_build, .process = tlsext_sni_client_process, }, .server = { .needs = tlsext_sni_server_needs, .build = tlsext_sni_server_build, .process = tlsext_sni_server_process, }, }, { .type = TLSEXT_TYPE_renegotiate, .messages = SSL_TLSEXT_MSG_CH | SSL_TLSEXT_MSG_SH, .client = { .needs = tlsext_ri_client_needs, .build = tlsext_ri_client_build, .process = tlsext_ri_client_process, }, .server = { .needs = tlsext_ri_server_needs, .build = tlsext_ri_server_build, .process = tlsext_ri_server_process, }, }, { .type = TLSEXT_TYPE_status_request, .messages = SSL_TLSEXT_MSG_CH | SSL_TLSEXT_MSG_CR | SSL_TLSEXT_MSG_CT, .client = { .needs = tlsext_ocsp_client_needs, .build = tlsext_ocsp_client_build, .process = tlsext_ocsp_client_process, }, .server = { .needs = tlsext_ocsp_server_needs, .build = tlsext_ocsp_server_build, .process = tlsext_ocsp_server_process, }, }, { .type = TLSEXT_TYPE_ec_point_formats, .messages = SSL_TLSEXT_MSG_CH | SSL_TLSEXT_MSG_SH, .client = { .needs = tlsext_ecpf_client_needs, .build = tlsext_ecpf_client_build, .process = tlsext_ecpf_client_process, }, .server = { .needs = tlsext_ecpf_server_needs, .build = tlsext_ecpf_server_build, .process = tlsext_ecpf_server_process, }, }, { .type = TLSEXT_TYPE_session_ticket, .messages = SSL_TLSEXT_MSG_CH | SSL_TLSEXT_MSG_SH, .client = { .needs = tlsext_sessionticket_client_needs, .build = tlsext_sessionticket_client_build, .process = tlsext_sessionticket_client_process, }, .server = { .needs = tlsext_sessionticket_server_needs, .build = tlsext_sessionticket_server_build, .process = tlsext_sessionticket_server_process, }, }, { .type = TLSEXT_TYPE_signature_algorithms, .messages = SSL_TLSEXT_MSG_CH | SSL_TLSEXT_MSG_CR, .client = { .needs = tlsext_sigalgs_client_needs, .build = tlsext_sigalgs_client_build, .process = tlsext_sigalgs_client_process, }, .server = { .needs = tlsext_sigalgs_server_needs, .build = tlsext_sigalgs_server_build, .process = tlsext_sigalgs_server_process, }, }, { .type = TLSEXT_TYPE_alpn, .messages = SSL_TLSEXT_MSG_CH | SSL_TLSEXT_MSG_EE, .client = { .needs = tlsext_alpn_client_needs, .build = tlsext_alpn_client_build, .process = tlsext_alpn_client_process, }, .server = { .needs = tlsext_alpn_server_needs, .build = tlsext_alpn_server_build, .process = tlsext_alpn_server_process, }, }, { .type = TLSEXT_TYPE_cookie, .messages = SSL_TLSEXT_MSG_CH | SSL_TLSEXT_MSG_HRR, .client = { .needs = tlsext_cookie_client_needs, .build = tlsext_cookie_client_build, .process = tlsext_cookie_client_process, }, .server = { .needs = tlsext_cookie_server_needs, .build = tlsext_cookie_server_build, .process = tlsext_cookie_server_process, }, }, #ifndef OPENSSL_NO_SRTP { .type = TLSEXT_TYPE_use_srtp, .messages = SSL_TLSEXT_MSG_CH | SSL_TLSEXT_MSG_SH /* XXX */ | SSL_TLSEXT_MSG_EE, .client = { .needs = tlsext_srtp_client_needs, .build = tlsext_srtp_client_build, .process = tlsext_srtp_client_process, }, .server = { .needs = tlsext_srtp_server_needs, .build = tlsext_srtp_server_build, .process = tlsext_srtp_server_process, }, }, #endif /* OPENSSL_NO_SRTP */ { .type = TLSEXT_TYPE_quic_transport_parameters, .messages = SSL_TLSEXT_MSG_CH | SSL_TLSEXT_MSG_EE, .client = { .needs = tlsext_quic_transport_parameters_client_needs, .build = tlsext_quic_transport_parameters_client_build, .process = tlsext_quic_transport_parameters_client_process, }, .server = { .needs = tlsext_quic_transport_parameters_server_needs, .build = tlsext_quic_transport_parameters_server_build, .process = tlsext_quic_transport_parameters_server_process, }, }, { .type = TLSEXT_TYPE_psk_key_exchange_modes, .messages = SSL_TLSEXT_MSG_CH, .client = { .needs = tlsext_psk_kex_modes_client_needs, .build = tlsext_psk_kex_modes_client_build, .process = tlsext_psk_kex_modes_client_process, }, .server = { .needs = tlsext_psk_kex_modes_server_needs, .build = tlsext_psk_kex_modes_server_build, .process = tlsext_psk_kex_modes_server_process, }, }, { .type = TLSEXT_TYPE_pre_shared_key, .messages = SSL_TLSEXT_MSG_CH | SSL_TLSEXT_MSG_SH, .client = { .needs = tlsext_psk_client_needs, .build = tlsext_psk_client_build, .process = tlsext_psk_client_process, }, .server = { .needs = tlsext_psk_server_needs, .build = tlsext_psk_server_build, .process = tlsext_psk_server_process, }, }, }; #define N_TLS_EXTENSIONS (sizeof(tls_extensions) / sizeof(*tls_extensions)) /* Ensure that extensions fit in a uint32_t bitmask. */ CTASSERT(N_TLS_EXTENSIONS <= (sizeof(uint32_t) * 8)); struct tlsext_data { CBS extensions[N_TLS_EXTENSIONS]; }; static struct tlsext_data * tlsext_data_new(void) { return calloc(1, sizeof(struct tlsext_data)); } static void tlsext_data_free(struct tlsext_data *td) { freezero(td, sizeof(*td)); } uint16_t tls_extension_type(const struct tls_extension *extension) { return extension->type; } const struct tls_extension * tls_extension_find(uint16_t type, size_t *tls_extensions_idx) { size_t i; for (i = 0; i < N_TLS_EXTENSIONS; i++) { if (tls_extensions[i].type == type) { *tls_extensions_idx = i; return &tls_extensions[i]; } } return NULL; } int tlsext_extension_seen(SSL *s, uint16_t type) { size_t idx; if (tls_extension_find(type, &idx) == NULL) return 0; return ((s->s3->hs.extensions_seen & (1 << idx)) != 0); } int tlsext_extension_processed(SSL *s, uint16_t type) { size_t idx; if (tls_extension_find(type, &idx) == NULL) return 0; return ((s->s3->hs.extensions_processed & (1 << idx)) != 0); } const struct tls_extension_funcs * tlsext_funcs(const struct tls_extension *tlsext, int is_server) { if (is_server) return &tlsext->server; return &tlsext->client; } int tlsext_randomize_build_order(SSL *s) { const struct tls_extension *psk_ext; size_t idx, new_idx, psk_idx; size_t alpn_idx = 0, sni_idx = 0; free(s->tlsext_build_order); s->tlsext_build_order_len = 0; if ((s->tlsext_build_order = calloc(sizeof(*s->tlsext_build_order), N_TLS_EXTENSIONS)) == NULL) return 0; s->tlsext_build_order_len = N_TLS_EXTENSIONS; /* RFC 8446, section 4.2 - PSK MUST be the last extension in the CH. */ if ((psk_ext = tls_extension_find(TLSEXT_TYPE_pre_shared_key, &psk_idx)) == NULL) return 0; s->tlsext_build_order[N_TLS_EXTENSIONS - 1] = psk_ext; /* Fisher-Yates shuffle with PSK fixed. */ for (idx = 0; idx < psk_idx; idx++) { new_idx = arc4random_uniform(idx + 1); s->tlsext_build_order[idx] = s->tlsext_build_order[new_idx]; s->tlsext_build_order[new_idx] = &tls_extensions[idx]; } /* * XXX - Apache2 special until year 2025: ensure that SNI precedes ALPN * for clients so that virtual host setups work correctly. */ if (s->server) return 1; for (idx = 0; idx < N_TLS_EXTENSIONS; idx++) { if (s->tlsext_build_order[idx]->type == TLSEXT_TYPE_alpn) alpn_idx = idx; if (s->tlsext_build_order[idx]->type == TLSEXT_TYPE_server_name) sni_idx = idx; } if (alpn_idx < sni_idx) { const struct tls_extension *tmp; tmp = s->tlsext_build_order[alpn_idx]; s->tlsext_build_order[alpn_idx] = s->tlsext_build_order[sni_idx]; s->tlsext_build_order[sni_idx] = tmp; } return 1; } int tlsext_linearize_build_order(SSL *s) { size_t idx; free(s->tlsext_build_order); s->tlsext_build_order_len = 0; if ((s->tlsext_build_order = calloc(sizeof(*s->tlsext_build_order), N_TLS_EXTENSIONS)) == NULL) return 0; s->tlsext_build_order_len = N_TLS_EXTENSIONS; for (idx = 0; idx < N_TLS_EXTENSIONS; idx++) s->tlsext_build_order[idx] = &tls_extensions[idx]; return 1; } static int tlsext_build(SSL *s, int is_server, uint16_t msg_type, CBB *cbb) { const struct tls_extension_funcs *ext; const struct tls_extension *tlsext; CBB extensions, extension_data; int extensions_present = 0; uint16_t tls_version; size_t i; tls_version = ssl_effective_tls_version(s); if (!CBB_add_u16_length_prefixed(cbb, &extensions)) return 0; for (i = 0; i < N_TLS_EXTENSIONS; i++) { tlsext = s->tlsext_build_order[i]; ext = tlsext_funcs(tlsext, is_server); /* RFC 8446 Section 4.2 */ if (tls_version >= TLS1_3_VERSION && !(tlsext->messages & msg_type)) continue; if (!ext->needs(s, msg_type)) continue; if (!CBB_add_u16(&extensions, tlsext->type)) return 0; if (!CBB_add_u16_length_prefixed(&extensions, &extension_data)) return 0; if (!ext->build(s, msg_type, &extension_data)) return 0; extensions_present = 1; } if (!extensions_present && (msg_type & (SSL_TLSEXT_MSG_CH | SSL_TLSEXT_MSG_SH)) != 0) CBB_discard_child(cbb); if (!CBB_flush(cbb)) return 0; return 1; } int tlsext_clienthello_hash_extension(SSL *s, uint16_t type, CBS *cbs) { /* * RFC 8446 4.1.2. For subsequent CH, early data will be removed, * cookie may be added, padding may be removed. */ struct tls13_ctx *ctx = s->tls13; if (type == TLSEXT_TYPE_early_data || type == TLSEXT_TYPE_cookie || type == TLSEXT_TYPE_padding) return 1; if (!tls13_clienthello_hash_update_bytes(ctx, (void *)&type, sizeof(type))) return 0; /* * key_share data may be changed, and pre_shared_key data may * be changed. */ if (type == TLSEXT_TYPE_pre_shared_key || type == TLSEXT_TYPE_key_share) return 1; if (!tls13_clienthello_hash_update(ctx, cbs)) return 0; return 1; } static int tlsext_parse(SSL *s, struct tlsext_data *td, int is_server, uint16_t msg_type, CBS *cbs, int *alert) { const struct tls_extension *tlsext; CBS extensions, extension_data; uint16_t type; size_t idx; uint16_t tls_version; int alert_desc; tls_version = ssl_effective_tls_version(s); s->s3->hs.extensions_seen = 0; /* An empty extensions block is valid. */ if (CBS_len(cbs) == 0) return 1; alert_desc = SSL_AD_DECODE_ERROR; if (!CBS_get_u16_length_prefixed(cbs, &extensions)) goto err; while (CBS_len(&extensions) > 0) { if (!CBS_get_u16(&extensions, &type)) goto err; if (!CBS_get_u16_length_prefixed(&extensions, &extension_data)) goto err; if (s->tlsext_debug_cb != NULL) s->tlsext_debug_cb(s, !is_server, type, (unsigned char *)CBS_data(&extension_data), CBS_len(&extension_data), s->tlsext_debug_arg); /* Unknown extensions are ignored. */ if ((tlsext = tls_extension_find(type, &idx)) == NULL) continue; if (tls_version >= TLS1_3_VERSION && is_server && msg_type == SSL_TLSEXT_MSG_CH) { if (!tlsext_clienthello_hash_extension(s, type, &extension_data)) goto err; } /* RFC 8446 Section 4.2 */ if (tls_version >= TLS1_3_VERSION && !(tlsext->messages & msg_type)) { alert_desc = SSL_AD_ILLEGAL_PARAMETER; goto err; } /* Check for duplicate known extensions. */ if ((s->s3->hs.extensions_seen & (1 << idx)) != 0) goto err; s->s3->hs.extensions_seen |= (1 << idx); CBS_dup(&extension_data, &td->extensions[idx]); } return 1; err: *alert = alert_desc; return 0; } static int tlsext_process(SSL *s, struct tlsext_data *td, int is_server, uint16_t msg_type, int *alert) { const struct tls_extension_funcs *ext; const struct tls_extension *tlsext; int alert_desc; size_t idx; alert_desc = SSL_AD_DECODE_ERROR; s->s3->hs.extensions_processed = 0; /* Run processing for present TLS extensions, in a defined order. */ for (idx = 0; idx < N_TLS_EXTENSIONS; idx++) { tlsext = &tls_extensions[idx]; if ((s->s3->hs.extensions_seen & (1 << idx)) == 0) continue; ext = tlsext_funcs(tlsext, is_server); if (ext->process == NULL) continue; if (!ext->process(s, msg_type, &td->extensions[idx], &alert_desc)) goto err; if (CBS_len(&td->extensions[idx]) != 0) goto err; s->s3->hs.extensions_processed |= (1 << idx); } return 1; err: *alert = alert_desc; return 0; } static void tlsext_server_reset_state(SSL *s) { s->tlsext_status_type = -1; s->s3->renegotiate_seen = 0; free(s->s3->alpn_selected); s->s3->alpn_selected = NULL; s->s3->alpn_selected_len = 0; s->srtp_profile = NULL; } int tlsext_server_build(SSL *s, uint16_t msg_type, CBB *cbb) { return tlsext_build(s, 1, msg_type, cbb); } int tlsext_server_parse(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { struct tlsext_data *td; int ret = 0; if ((td = tlsext_data_new()) == NULL) goto err; /* XXX - this should be done by the caller... */ if (msg_type == SSL_TLSEXT_MSG_CH) tlsext_server_reset_state(s); if (!tlsext_parse(s, td, 1, msg_type, cbs, alert)) goto err; if (!tlsext_process(s, td, 1, msg_type, alert)) goto err; ret = 1; err: tlsext_data_free(td); return ret; } static void tlsext_client_reset_state(SSL *s) { s->s3->renegotiate_seen = 0; free(s->s3->alpn_selected); s->s3->alpn_selected = NULL; s->s3->alpn_selected_len = 0; } int tlsext_client_build(SSL *s, uint16_t msg_type, CBB *cbb) { return tlsext_build(s, 0, msg_type, cbb); } int tlsext_client_parse(SSL *s, uint16_t msg_type, CBS *cbs, int *alert) { struct tlsext_data *td; int ret = 0; if ((td = tlsext_data_new()) == NULL) goto err; /* XXX - this should be done by the caller... */ if (msg_type == SSL_TLSEXT_MSG_SH) tlsext_client_reset_state(s); if (!tlsext_parse(s, td, 0, msg_type, cbs, alert)) goto err; if (!tlsext_process(s, td, 0, msg_type, alert)) goto err; ret = 1; err: tlsext_data_free(td); return ret; }