From 5ebeb8b5d90f9f47418b6b8d898ace8f1b4d4104 Mon Sep 17 00:00:00 2001 From: Adam Langley Date: Mon, 15 Apr 2013 18:07:47 -0400 This change adds support for ALPN[1] in OpenSSL. ALPN is the IETF blessed version of NPN and we'll be supporting both ALPN and NPN for some time yet. [1] https://tools.ietf.org/html/draft-ietf-tls-applayerprotoneg-00 --- apps/s_client.c | 40 +++++++++++++- ssl/s3_lib.c | 13 +++++ ssl/ssl.h | 45 +++++++++++++++ ssl/ssl3.h | 10 ++++ ssl/ssl_lib.c | 87 +++++++++++++++++++++++++++++ ssl/t1_lib.c | 167 +++++++++++++++++++++++++++++++++++++++++++++++++++++++- ssl/tls1.h | 3 + 7 files changed, 362 insertions(+), 3 deletions(-) diff --git a/apps/s_client.c b/apps/s_client.c index 791e277..cb1efcd 100644 --- a/apps/s_client.c +++ b/apps/s_client.c @@ -359,6 +359,7 @@ static void sc_usage(void) BIO_printf(bio_err," -no_ticket - disable use of RFC4507bis session tickets\n"); # ifndef OPENSSL_NO_NEXTPROTONEG BIO_printf(bio_err," -nextprotoneg arg - enable NPN extension, considering named protocols supported (comma-separated list)\n"); + BIO_printf(bio_err," -alpn arg - enable ALPN extension, considering named protocols supported (comma-separated list)\n"); # endif #endif BIO_printf(bio_err," -cutthrough - enable 1-RTT full-handshake for strong ciphers\n"); @@ -611,6 +612,7 @@ int MAIN(int argc, char **argv) {NULL,0}; # ifndef OPENSSL_NO_NEXTPROTONEG const char *next_proto_neg_in = NULL; + const char *alpn_in = NULL; # endif #endif char *sess_in = NULL; @@ -883,6 +885,11 @@ int MAIN(int argc, char **argv) if (--argc < 1) goto bad; next_proto_neg_in = *(++argv); } + else if (strcmp(*argv,"-alpn") == 0) + { + if (--argc < 1) goto bad; + alpn_in = *(++argv); + } # endif #endif else if (strcmp(*argv,"-cutthrough") == 0) @@ -1157,9 +1164,23 @@ bad: */ if (socket_type == SOCK_DGRAM) SSL_CTX_set_read_ahead(ctx, 1); -#if !defined(OPENSSL_NO_TLSEXT) && !defined(OPENSSL_NO_NEXTPROTONEG) +#if !defined(OPENSSL_NO_TLSEXT) +# if !defined(OPENSSL_NO_NEXTPROTONEG) if (next_proto.data) SSL_CTX_set_next_proto_select_cb(ctx, next_proto_cb, &next_proto); +# endif + if (alpn_in) + { + unsigned short alpn_len; + unsigned char *alpn = next_protos_parse(&alpn_len, alpn_in); + + if (alpn == NULL) + { + BIO_printf(bio_err, "Error parsing -alpn argument\n"); + goto end; + } + SSL_CTX_set_alpn_protos(ctx, alpn, alpn_len); + } #endif /* Enable handshake cutthrough for client connections using @@ -2077,7 +2098,8 @@ static void print_stuff(BIO *bio, SSL *s, int full) } #endif -#if !defined(OPENSSL_NO_TLSEXT) && !defined(OPENSSL_NO_NEXTPROTONEG) +#if !defined(OPENSSL_NO_TLSEXT) +# if !defined(OPENSSL_NO_NEXTPROTONEG) if (next_proto.status != -1) { const unsigned char *proto; unsigned int proto_len; @@ -2086,6 +2108,20 @@ static void print_stuff(BIO *bio, SSL *s, int full) BIO_write(bio, proto, proto_len); BIO_write(bio, "\n", 1); } + { + const unsigned char *proto; + unsigned int proto_len; + SSL_get0_alpn_selected(s, &proto, &proto_len); + if (proto_len > 0) + { + BIO_printf(bio, "ALPN protocol: "); + BIO_write(bio, proto, proto_len); + BIO_write(bio, "\n", 1); + } + else + BIO_printf(bio, "No ALPN negotiated\n"); + } +# endif #endif #ifndef OPENSSL_NO_SRTP diff --git a/ssl/s3_lib.c b/ssl/s3_lib.c index 5e46393..2cd1654 100644 --- a/ssl/s3_lib.c +++ b/ssl/s3_lib.c @@ -2996,6 +2996,11 @@ void ssl3_free(SSL *s) BIO_free(s->s3->handshake_buffer); } if (s->s3->handshake_dgst) ssl3_free_digest_list(s); +#ifndef OPENSSL_NO_TLSEXT + if (s->s3->alpn_selected) + OPENSSL_free(s->s3->alpn_selected); +#endif + #ifndef OPENSSL_NO_SRP SSL_SRP_CTX_free(s); #endif @@ -3055,6 +3060,14 @@ void ssl3_clear(SSL *s) if (s->s3->handshake_dgst) { ssl3_free_digest_list(s); } + +#if !defined(OPENSSL_NO_TLSEXT) + if (s->s3->alpn_selected) + { + free(s->s3->alpn_selected); + s->s3->alpn_selected = NULL; + } +#endif memset(s->s3,0,sizeof *s->s3); s->s3->rbuf.buf = rp; s->s3->wbuf.buf = wp; diff --git a/ssl/ssl.h b/ssl/ssl.h index e8c73fa..612c7aa 100644 --- a/ssl/ssl.h +++ b/ssl/ssl.h @@ -1019,6 +1019,31 @@ struct ssl_ctx_st void *arg); void *next_proto_select_cb_arg; # endif + + /* ALPN information + * (we are in the process of transitioning from NPN to ALPN.) */ + + /* For a server, this contains a callback function that allows the + * server to select the protocol for the connection. + * out: on successful return, this must point to the raw protocol + * name (without the length prefix). + * outlen: on successful return, this contains the length of |*out|. + * in: points to the client's list of supported protocols in + * wire-format. + * inlen: the length of |in|. */ + int (*alpn_select_cb)(SSL *s, + const unsigned char **out, + unsigned char *outlen, + const unsigned char* in, + unsigned int inlen, + void *arg); + void *alpn_select_cb_arg; + + /* For a client, this contains the list of supported protocols in wire + * format. */ + unsigned char* alpn_client_proto_list; + unsigned alpn_client_proto_list_len; + /* SRTP profiles we are willing to do from RFC 5764 */ STACK_OF(SRTP_PROTECTION_PROFILE) *srtp_profiles; @@ -1120,6 +1145,21 @@ void SSL_get0_next_proto_negotiated(const SSL *s, #define OPENSSL_NPN_NO_OVERLAP 2 #endif +int SSL_CTX_set_alpn_protos(SSL_CTX *ctx, const unsigned char* protos, + unsigned protos_len); +int SSL_set_alpn_protos(SSL *ssl, const unsigned char* protos, + unsigned protos_len); +void SSL_CTX_set_alpn_select_cb(SSL_CTX* ctx, + int (*cb) (SSL *ssl, + const unsigned char **out, + unsigned char *outlen, + const unsigned char *in, + unsigned int inlen, + void *arg), + void *arg); +void SSL_get0_alpn_selected(const SSL *ssl, const unsigned char **data, + unsigned *len); + #ifndef OPENSSL_NO_PSK /* the maximum length of the buffer given to callbacks containing the * resulting identity/psk */ @@ -1422,6 +1462,11 @@ struct ssl_st char tlsext_channel_id_enabled; /* The client's Channel ID private key. */ EVP_PKEY *tlsext_channel_id_private; + + /* For a client, this contains the list of supported protocols in wire + * format. */ + unsigned char* alpn_client_proto_list; + unsigned alpn_client_proto_list_len; #else #define session_ctx ctx #endif /* OPENSSL_NO_TLSEXT */ diff --git a/ssl/ssl3.h b/ssl/ssl3.h index 3229995..28c46d5 100644 --- a/ssl/ssl3.h +++ b/ssl/ssl3.h @@ -551,6 +551,16 @@ typedef struct ssl3_state_st * each are big-endian values. */ unsigned char tlsext_channel_id[64]; + /* ALPN information + * (we are in the process of transitioning from NPN to ALPN.) */ + + /* In a server these point to the selected ALPN protocol after the + * ClientHello has been processed. In a client these contain the + * protocol that the server selected once the ServerHello has been + * processed. */ + unsigned char *alpn_selected; + unsigned alpn_selected_len; + /* These point to the digest function to use for signatures made with * each type of public key. A NULL value indicates that the default * digest should be used, which is SHA1 as of TLS 1.2. diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c index e360550..b472423 100644 --- a/ssl/ssl_lib.c +++ b/ssl/ssl_lib.c @@ -359,6 +359,17 @@ SSL *SSL_new(SSL_CTX *ctx) # ifndef OPENSSL_NO_NEXTPROTONEG s->next_proto_negotiated = NULL; # endif + + if (s->ctx->alpn_client_proto_list) + { + s->alpn_client_proto_list = + OPENSSL_malloc(s->ctx->alpn_client_proto_list_len); + if (s->alpn_client_proto_list == NULL) + goto err; + memcpy(s->alpn_client_proto_list, s->ctx->alpn_client_proto_list, + s->ctx->alpn_client_proto_list_len); + s->alpn_client_proto_list_len = s->ctx->alpn_client_proto_list_len; + } #endif s->verify_result=X509_V_OK; @@ -564,6 +575,8 @@ void SSL_free(SSL *s) OPENSSL_free(s->tlsext_ocsp_resp); if (s->tlsext_channel_id_private) EVP_PKEY_free(s->tlsext_channel_id_private); + if (s->alpn_client_proto_list) + OPENSSL_free(s->alpn_client_proto_list); #endif if (s->client_CA != NULL) @@ -1615,6 +1628,78 @@ void SSL_CTX_set_next_proto_select_cb(SSL_CTX *ctx, int (*cb) (SSL *s, unsigned ctx->next_proto_select_cb_arg = arg; } # endif + +/* SSL_CTX_set_alpn_protos sets the ALPN protocol list on |ctx| to |protos|. + * |protos| must be in wire-format (i.e. a series of non-empty, 8-bit + * length-prefixed strings). + * + * Returns 0 on success. */ +int SSL_CTX_set_alpn_protos(SSL_CTX *ctx, const unsigned char* protos, + unsigned protos_len) + { + if (ctx->alpn_client_proto_list) + OPENSSL_free(ctx->alpn_client_proto_list); + + ctx->alpn_client_proto_list = OPENSSL_malloc(protos_len); + if (!ctx->alpn_client_proto_list) + return 1; + memcpy(ctx->alpn_client_proto_list, protos, protos_len); + ctx->alpn_client_proto_list_len = protos_len; + + return 0; + } + +/* SSL_set_alpn_protos sets the ALPN protocol list on |ssl| to |protos|. + * |protos| must be in wire-format (i.e. a series of non-empty, 8-bit + * length-prefixed strings). + * + * Returns 0 on success. */ +int SSL_set_alpn_protos(SSL *ssl, const unsigned char* protos, + unsigned protos_len) + { + if (ssl->alpn_client_proto_list) + OPENSSL_free(ssl->alpn_client_proto_list); + + ssl->alpn_client_proto_list = OPENSSL_malloc(protos_len); + if (!ssl->alpn_client_proto_list) + return 1; + memcpy(ssl->alpn_client_proto_list, protos, protos_len); + ssl->alpn_client_proto_list_len = protos_len; + + return 0; + } + +/* SSL_CTX_set_alpn_select_cb sets a callback function on |ctx| that is called + * during ClientHello processing in order to select an ALPN protocol from the + * client's list of offered protocols. */ +void SSL_CTX_set_alpn_select_cb(SSL_CTX* ctx, + int (*cb) (SSL *ssl, + const unsigned char **out, + unsigned char *outlen, + const unsigned char *in, + unsigned int inlen, + void *arg), + void *arg) + { + ctx->alpn_select_cb = cb; + ctx->alpn_select_cb_arg = arg; + } + +/* SSL_get0_alpn_selected gets the selected ALPN protocol (if any) from |ssl|. + * On return it sets |*data| to point to |*len| bytes of protocol name (not + * including the leading length-prefix byte). If the server didn't respond with + * a negotiated protocol then |*len| will be zero. */ +void SSL_get0_alpn_selected(const SSL *ssl, const unsigned char **data, + unsigned *len) + { + *data = NULL; + if (ssl->s3) + *data = ssl->s3->alpn_selected; + if (*data == NULL) + *len = 0; + else + *len = ssl->s3->alpn_selected_len; + } #endif int SSL_export_keying_material(SSL *s, unsigned char *out, size_t olen, @@ -1955,6 +2040,8 @@ void SSL_CTX_free(SSL_CTX *a) #ifndef OPENSSL_NO_TLSEXT if (a->tlsext_channel_id_private) EVP_PKEY_free(a->tlsext_channel_id_private); + if (a->alpn_client_proto_list != NULL) + OPENSSL_free(a->alpn_client_proto_list); #endif OPENSSL_free(a); diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c index 1f93a6f..b2e049a 100644 --- a/ssl/t1_lib.c +++ b/ssl/t1_lib.c @@ -659,6 +659,18 @@ unsigned char *ssl_add_clienthello_tlsext(SSL *s, unsigned char *p, unsigned cha s2n(0,ret); } + if (s->alpn_client_proto_list && !s->s3->tmp.finish_md_len) + { + if ((size_t)(limit - ret) < 6 + s->alpn_client_proto_list_len) + return NULL; + s2n(TLSEXT_TYPE_application_layer_protocol_negotiation,ret); + s2n(2 + s->alpn_client_proto_list_len,ret); + s2n(s->alpn_client_proto_list_len,ret); + memcpy(ret, s->alpn_client_proto_list, + s->alpn_client_proto_list_len); + ret += s->alpn_client_proto_list_len; + } + #ifndef OPENSSL_NO_SRTP if(SSL_get_srtp_profiles(s)) { @@ -879,6 +891,21 @@ unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *p, unsigned cha s2n(0,ret); } + if (s->s3->alpn_selected) + { + const unsigned char *selected = s->s3->alpn_selected; + unsigned len = s->s3->alpn_selected_len; + + if ((long)(limit - ret - 4 - 2 - 1 - len) < 0) + return NULL; + s2n(TLSEXT_TYPE_application_layer_protocol_negotiation,ret); + s2n(3 + len,ret); + s2n(1 + len,ret); + *ret++ = len; + memcpy(ret, selected, len); + ret += len; + } + if ((extdatalen = ret-p-2)== 0) return p; @@ -966,6 +993,76 @@ static void ssl_check_for_safari(SSL *s, const unsigned char *data, const unsign s->is_probably_safari = 1; } +/* tls1_alpn_handle_client_hello is called to process the ALPN extension in a + * ClientHello. + * data: the contents of the extension, not including the type and length. + * data_len: the number of bytes in |data| + * al: a pointer to the alert value to send in the event of a non-zero + * return. + * + * returns: 0 on success. */ +static int tls1_alpn_handle_client_hello(SSL *s, const unsigned char *data, + unsigned data_len, int *al) + { + unsigned i; + unsigned proto_len; + const unsigned char *selected; + unsigned char selected_len; + int r; + + if (s->ctx->alpn_select_cb == NULL) + return 0; + + if (data_len < 2) + goto parse_error; + + /* data should contain a uint16 length followed by a series of 8-bit, + * length-prefixed strings. */ + i = ((unsigned) data[0]) << 8 | + ((unsigned) data[1]); + data_len -= 2; + data += 2; + if (data_len != i) + goto parse_error; + + if (data_len < 2) + goto parse_error; + + for (i = 0; i < data_len;) + { + proto_len = data[i]; + i++; + + if (proto_len == 0) + goto parse_error; + + if (i + proto_len < i || i + proto_len > data_len) + goto parse_error; + + i += proto_len; + } + + r = s->ctx->alpn_select_cb(s, &selected, &selected_len, data, data_len, + s->ctx->alpn_select_cb_arg); + if (r == SSL_TLSEXT_ERR_OK) { + if (s->s3->alpn_selected) + OPENSSL_free(s->s3->alpn_selected); + s->s3->alpn_selected = OPENSSL_malloc(selected_len); + if (!s->s3->alpn_selected) + { + *al = SSL_AD_INTERNAL_ERROR; + return -1; + } + memcpy(s->s3->alpn_selected, selected, selected_len); + s->s3->alpn_selected_len = selected_len; + } + return 0; + +parse_error: + *al = SSL_AD_DECODE_ERROR; + return -1; + } + int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d, int n, int *al) { unsigned short type; @@ -988,6 +1085,12 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d, in s->s3->next_proto_neg_seen = 0; #endif + if (s->s3->alpn_selected) + { + OPENSSL_free(s->s3->alpn_selected); + s->s3->alpn_selected = NULL; + } + #ifndef OPENSSL_NO_HEARTBEATS s->tlsext_heartbeat &= ~(SSL_TLSEXT_HB_ENABLED | SSL_TLSEXT_HB_DONT_SEND_REQUESTS); @@ -1420,7 +1523,8 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d, in #endif #ifndef OPENSSL_NO_NEXTPROTONEG else if (type == TLSEXT_TYPE_next_proto_neg && - s->s3->tmp.finish_md_len == 0) + s->s3->tmp.finish_md_len == 0 && + s->s3->alpn_selected == NULL) { /* We shouldn't accept this extension on a * renegotiation. @@ -1444,6 +1548,16 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d, in else if (type == TLSEXT_TYPE_channel_id && s->tlsext_channel_id_enabled) s->s3->tlsext_channel_id_valid = 1; + else if (type == TLSEXT_TYPE_application_layer_protocol_negotiation && + s->ctx->alpn_select_cb && + s->s3->tmp.finish_md_len == 0) + { + if (tls1_alpn_handle_client_hello(s, data, size, al) != 0) + return 0; + /* ALPN takes precedence over NPN. */ + s->s3->next_proto_neg_seen = 0; + } + /* session ticket processed earlier */ #ifndef OPENSSL_NO_SRTP else if (type == TLSEXT_TYPE_use_srtp) @@ -1508,6 +1622,12 @@ int ssl_parse_serverhello_tlsext(SSL *s, unsigned char **p, unsigned char *d, in s->s3->next_proto_neg_seen = 0; #endif + if (s->s3->alpn_selected) + { + OPENSSL_free(s->s3->alpn_selected); + s->s3->alpn_selected = NULL; + } + #ifndef OPENSSL_NO_HEARTBEATS s->tlsext_heartbeat &= ~(SSL_TLSEXT_HB_ENABLED | SSL_TLSEXT_HB_DONT_SEND_REQUESTS); @@ -1677,6 +1797,51 @@ int ssl_parse_serverhello_tlsext(SSL *s, unsigned char **p, unsigned char *d, in else if (type == TLSEXT_TYPE_channel_id) s->s3->tlsext_channel_id_valid = 1; + else if (type == TLSEXT_TYPE_application_layer_protocol_negotiation) + { + unsigned len; + + /* We must have requested it. */ + if (s->alpn_client_proto_list == NULL) + { + *al = TLS1_AD_UNSUPPORTED_EXTENSION; + return 0; + } + if (size < 4) + { + *al = TLS1_AD_DECODE_ERROR; + return 0; + } + /* The extension data consists of: + * uint16 list_length + * uint8 proto_length; + * uint8 proto[proto_length]; */ + len = data[0]; + len <<= 8; + len |= data[1]; + if (len != (unsigned) size - 2) + { + *al = TLS1_AD_DECODE_ERROR; + return 0; + } + len = data[2]; + if (len != (unsigned) size - 3) + { + *al = TLS1_AD_DECODE_ERROR; + return 0; + } + if (s->s3->alpn_selected) + OPENSSL_free(s->s3->alpn_selected); + s->s3->alpn_selected = OPENSSL_malloc(len); + if (!s->s3->alpn_selected) + { + *al = TLS1_AD_INTERNAL_ERROR; + return 0; + } + memcpy(s->s3->alpn_selected, data + 3, len); + s->s3->alpn_selected_len = len; + } + else if (type == TLSEXT_TYPE_renegotiate) { if(!ssl_parse_serverhello_renegotiate_ext(s, data, size, al)) diff --git a/ssl/tls1.h b/ssl/tls1.h index 8fc1ff4..c6670f4 100644 --- a/ssl/tls1.h +++ b/ssl/tls1.h @@ -230,6 +230,9 @@ extern "C" { /* ExtensionType value from RFC5620 */ #define TLSEXT_TYPE_heartbeat 15 +/* ExtensionType value from draft-ietf-tls-applayerprotoneg-00 */ +#define TLSEXT_TYPE_application_layer_protocol_negotiation 16 + /* ExtensionType value from RFC4507 */ #define TLSEXT_TYPE_session_ticket 35 -- 1.8.2.1