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Move DTLS CCS processing into the state machine

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Continuing on from the previous commit this moves the processing of DTLS
CCS messages out of the record layer and into the state machine.

Reviewed-by: Tim Hudson <tjh@openssl.org>
This commit is contained in:
Matt Caswell 2015-06-02 11:33:07 +01:00
parent 657da85eea
commit c69f2adf71
6 changed files with 129 additions and 92 deletions
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59
ssl/d1_both.c
View file

@ -160,8 +160,8 @@ static void dtls1_set_message_header_int(SSL *s, unsigned char mt,
unsigned short seq_num,
unsigned long frag_off,
unsigned long frag_len);
static long dtls1_get_message_fragment(SSL *s, int st1, int stn, long max,
int *ok);
static long dtls1_get_message_fragment(SSL *s, int st1, int stn, int mt,
long max, int *ok);
static hm_fragment *dtls1_hm_fragment_new(unsigned long frag_len,
int reassembly)
@ -470,7 +470,7 @@ long dtls1_get_message(SSL *s, int st1, int stn, int mt, long max, int *ok)
memset(msg_hdr, 0, sizeof(*msg_hdr));
again:
i = dtls1_get_message_fragment(s, st1, stn, max, ok);
i = dtls1_get_message_fragment(s, st1, stn, mt, max, ok);
if (i == DTLS1_HM_BAD_FRAGMENT || i == DTLS1_HM_FRAGMENT_RETRY) {
/* bad fragment received */
goto again;
@ -485,6 +485,20 @@ long dtls1_get_message(SSL *s, int st1, int stn, int mt, long max, int *ok)
}
p = (unsigned char *)s->init_buf->data;
if (mt == SSL3_MT_CHANGE_CIPHER_SPEC) {
if (s->msg_callback) {
s->msg_callback(0, s->version, SSL3_RT_CHANGE_CIPHER_SPEC,
p, 1, s, s->msg_callback_arg);
}
/*
* This isn't a real handshake message so skip the processing below.
* dtls1_get_message_fragment() will never return a CCS if mt == -1,
* so we are ok to continue in that case.
*/
return i;
}
msg_len = msg_hdr->msg_len;
/* reconstruct message header */
@ -835,11 +849,11 @@ dtls1_process_out_of_seq_message(SSL *s, const struct hm_header_st *msg_hdr,
}
static long
dtls1_get_message_fragment(SSL *s, int st1, int stn, long max, int *ok)
dtls1_get_message_fragment(SSL *s, int st1, int stn, int mt, long max, int *ok)
{
unsigned char wire[DTLS1_HM_HEADER_LENGTH];
unsigned long len, frag_off, frag_len;
int i, al;
int i, al, recvd_type;
struct hm_header_st msg_hdr;
redo:
@ -851,13 +865,46 @@ dtls1_get_message_fragment(SSL *s, int st1, int stn, long max, int *ok)
}
/* read handshake message header */
i = s->method->ssl_read_bytes(s, SSL3_RT_HANDSHAKE, NULL, wire,
i = s->method->ssl_read_bytes(s, SSL3_RT_HANDSHAKE, &recvd_type, wire,
DTLS1_HM_HEADER_LENGTH, 0);
if (i <= 0) { /* nbio, or an error */
s->rwstate = SSL_READING;
*ok = 0;
return i;
}
if(recvd_type == SSL3_RT_CHANGE_CIPHER_SPEC) {
/* This isn't a real handshake message - its a CCS.
* There is no message sequence number in a CCS to give us confidence
* that this was really intended to be at this point in the handshake
* sequence. Therefore we only allow this if we were explicitly looking
* for it (i.e. if |mt| is -1 we still don't allow it).
*/
if(mt == SSL3_MT_CHANGE_CIPHER_SPEC) {
if (wire[0] != SSL3_MT_CCS) {
al = SSL_AD_UNEXPECTED_MESSAGE;
SSLerr(SSL_F_SSL3_GET_MESSAGE, SSL_R_BAD_CHANGE_CIPHER_SPEC);
goto f_err;
}
memcpy(s->init_buf->data, wire, i);
s->init_num = i - 1;
s->init_msg = s->init_buf->data + 1;
s->s3->tmp.message_type = SSL3_MT_CHANGE_CIPHER_SPEC;
s->s3->tmp.message_size = i - 1;
s->state = stn;
*ok = 1;
return i-1;
} else {
/*
* We weren't expecting a CCS yet. Probably something got
* re-ordered or this is a retransmit. We should drop this and try
* again.
*/
s->init_num = 0;
goto redo;
}
}
/* Handshake fails if message header is incomplete */
if (i != DTLS1_HM_HEADER_LENGTH) {
al = SSL_AD_UNEXPECTED_MESSAGE;

19
ssl/d1_clnt.c
View file

@ -271,7 +271,6 @@ int dtls1_connect(SSL *s)
memset(s->s3->client_random, 0, sizeof(s->s3->client_random));
s->d1->send_cookie = 0;
s->hit = 0;
s->d1->change_cipher_spec_ok = 0;
/*
* Should have been reset by ssl3_get_finished, too.
*/
@ -376,7 +375,7 @@ int dtls1_connect(SSL *s)
sizeof(sctpauthkey), sctpauthkey);
#endif
s->state = SSL3_ST_CR_FINISHED_A;
s->state = SSL3_ST_CR_CHANGE_A;
} else
s->state = DTLS1_ST_CR_HELLO_VERIFY_REQUEST_A;
}
@ -628,7 +627,7 @@ int dtls1_connect(SSL *s)
if (s->tlsext_ticket_expected)
s->s3->tmp.next_state = SSL3_ST_CR_SESSION_TICKET_A;
else
s->s3->tmp.next_state = SSL3_ST_CR_FINISHED_A;
s->s3->tmp.next_state = SSL3_ST_CR_CHANGE_A;
}
s->init_num = 0;
break;
@ -638,7 +637,7 @@ int dtls1_connect(SSL *s)
ret = ssl3_get_new_session_ticket(s);
if (ret <= 0)
goto end;
s->state = SSL3_ST_CR_FINISHED_A;
s->state = SSL3_ST_CR_CHANGE_A;
s->init_num = 0;
break;
@ -651,9 +650,19 @@ int dtls1_connect(SSL *s)
s->init_num = 0;
break;
case SSL3_ST_CR_CHANGE_A:
case SSL3_ST_CR_CHANGE_B:
ret = ssl3_get_change_cipher_spec(s, SSL3_ST_CR_CHANGE_A,
SSL3_ST_CR_CHANGE_B);
if (ret <= 0)
goto end;
s->state = SSL3_ST_CR_FINISHED_A;
s->init_num = 0;
break;
case SSL3_ST_CR_FINISHED_A:
case SSL3_ST_CR_FINISHED_B:
s->d1->change_cipher_spec_ok = 1;
ret = ssl3_get_finished(s, SSL3_ST_CR_FINISHED_A,
SSL3_ST_CR_FINISHED_B);
if (ret <= 0)

31
ssl/d1_srvr.c
View file

@ -257,7 +257,6 @@ int dtls1_accept(SSL *s)
}
s->init_num = 0;
s->d1->change_cipher_spec_ok = 0;
/*
* Should have been reset by ssl3_get_finished, too.
*/
@ -378,7 +377,7 @@ int dtls1_accept(SSL *s)
goto end;
}
s->state = SSL3_ST_SR_FINISHED_A;
s->state = SSL3_ST_SR_CHANGE_A;
break;
case DTLS1_SCTP_ST_SW_WRITE_SOCK:
@ -624,7 +623,7 @@ int dtls1_accept(SSL *s)
* pub key in a certificate, the CertificateVerify message is
* not sent.
*/
s->state = SSL3_ST_SR_FINISHED_A;
s->state = SSL3_ST_SR_CHANGE_A;
s->init_num = 0;
} else if (SSL_USE_SIGALGS(s)) {
s->state = SSL3_ST_SR_CERT_VRFY_A;
@ -675,23 +674,23 @@ int dtls1_accept(SSL *s)
s->state = DTLS1_SCTP_ST_SR_READ_SOCK;
else
#endif
s->state = SSL3_ST_SR_FINISHED_A;
s->state = SSL3_ST_SR_CHANGE_A;
s->init_num = 0;
break;
case SSL3_ST_SR_CHANGE_A:
case SSL3_ST_SR_CHANGE_B:
ret = ssl3_get_change_cipher_spec(s, SSL3_ST_SR_CHANGE_A,
SSL3_ST_SR_CHANGE_B);
if (ret <= 0)
goto end;
s->state = SSL3_ST_SR_FINISHED_A;
s->init_num = 0;
break;
case SSL3_ST_SR_FINISHED_A:
case SSL3_ST_SR_FINISHED_B:
/*
* Enable CCS. Receiving a CCS clears the flag, so make
* sure not to re-enable it to ban duplicates. This *should* be the
* first time we have received one - but we check anyway to be
* cautious.
* s->s3->change_cipher_spec is set when a CCS is
* processed in d1_pkt.c, and remains set until
* the client's Finished message is read.
*/
if (!s->s3->change_cipher_spec)
s->d1->change_cipher_spec_ok = 1;
ret = ssl3_get_finished(s, SSL3_ST_SR_FINISHED_A,
SSL3_ST_SR_FINISHED_B);
if (ret <= 0)
@ -779,7 +778,7 @@ int dtls1_accept(SSL *s)
goto end;
s->state = SSL3_ST_SW_FLUSH;
if (s->hit) {
s->s3->tmp.next_state = SSL3_ST_SR_FINISHED_A;
s->s3->tmp.next_state = SSL3_ST_SR_CHANGE_A;
#ifndef OPENSSL_NO_SCTP
/*

70
ssl/record/rec_layer_d1.c
View file

@ -379,8 +379,9 @@ int dtls1_process_buffered_records(SSL *s)
* (possibly multiple records if we still don't have anything to return).
*
* This function must handle any surprises the peer may have for us, such as
* Alert records (e.g. close_notify), ChangeCipherSpec records (not really
* a surprise, but handled as if it were), or renegotiation requests.
* Alert records (e.g. close_notify) or renegotiation requests. ChangeCipherSpec
* messages are treated as if they were handshake messages *if* the |recd_type|
* argument is non NULL.
* Also if record payloads contain fragments too small to process, we store
* them until there is enough for the respective protocol (the record protocol
* may use arbitrary fragmentation and even interleaving):
@ -538,9 +539,14 @@ int dtls1_read_bytes(SSL *s, int type, int *recvd_type, unsigned char *buf,
return (0);
}
if (type == SSL3_RECORD_get_type(rr)) {
/* SSL3_RT_APPLICATION_DATA or
* SSL3_RT_HANDSHAKE */
if (type == SSL3_RECORD_get_type(rr)
|| (SSL3_RECORD_get_type(rr) == SSL3_RT_CHANGE_CIPHER_SPEC
&& type == SSL3_RT_HANDSHAKE && recvd_type != NULL)) {
/*
* SSL3_RT_APPLICATION_DATA or
* SSL3_RT_HANDSHAKE or
* SSL3_RT_CHANGE_CIPHER_SPEC
*/
/*
* make sure that we are not getting application data when we are
* doing a handshake for the first time
@ -552,6 +558,9 @@ int dtls1_read_bytes(SSL *s, int type, int *recvd_type, unsigned char *buf,
goto f_err;
}
if (recvd_type != NULL)
*recvd_type = SSL3_RECORD_get_type(rr);
if (len <= 0)
return (len);
@ -858,59 +867,11 @@ int dtls1_read_bytes(SSL *s, int type, int *recvd_type, unsigned char *buf,
}
if (SSL3_RECORD_get_type(rr) == SSL3_RT_CHANGE_CIPHER_SPEC) {
unsigned int ccs_hdr_len = DTLS1_CCS_HEADER_LENGTH;
if (s->version == DTLS1_BAD_VER)
ccs_hdr_len = 3;
/*
* 'Change Cipher Spec' is just a single byte, so we know exactly
* what the record payload has to look like
*/
/* XDTLS: check that epoch is consistent */
if ((SSL3_RECORD_get_length(rr) != ccs_hdr_len)
|| (SSL3_RECORD_get_off(rr) != 0)
|| (SSL3_RECORD_get_data(rr)[0] != SSL3_MT_CCS)) {
i = SSL_AD_ILLEGAL_PARAMETER;
SSLerr(SSL_F_DTLS1_READ_BYTES, SSL_R_BAD_CHANGE_CIPHER_SPEC);
goto err;
}
SSL3_RECORD_set_length(rr, 0);
if (s->msg_callback)
s->msg_callback(0, s->version, SSL3_RT_CHANGE_CIPHER_SPEC,
SSL3_RECORD_get_data(rr), 1, s, s->msg_callback_arg);
/*
* We can't process a CCS now, because previous handshake messages
* are still missing, so just drop it.
*/
if (!s->d1->change_cipher_spec_ok) {
goto start;
}
s->d1->change_cipher_spec_ok = 0;
s->s3->change_cipher_spec = 1;
if (!ssl3_do_change_cipher_spec(s))
goto err;
/* do this whenever CCS is processed */
dtls1_reset_seq_numbers(s, SSL3_CC_READ);
if (s->version == DTLS1_BAD_VER)
s->d1->handshake_read_seq++;
#ifndef OPENSSL_NO_SCTP
/*
* Remember that a CCS has been received, so that an old key of
* SCTP-Auth can be deleted when a CCS is sent. Will be ignored if no
* SCTP is used
*/
BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_AUTH_CCS_RCVD, 1, NULL);
#endif
SSL3_RECORD_set_length(rr, 0);
goto start;
}
@ -1026,7 +987,6 @@ int dtls1_read_bytes(SSL *s, int type, int *recvd_type, unsigned char *buf,
f_err:
ssl3_send_alert(s, SSL3_AL_FATAL, al);
err:
return (-1);
}

37
ssl/s3_both.c
View file

@ -240,12 +240,23 @@ int ssl3_get_change_cipher_spec(SSL *s, int a, int b)
/*
* 'Change Cipher Spec' is just a single byte, which should already have
* been consumed by ssl_get_message() so there should be no bytes left
* been consumed by ssl_get_message() so there should be no bytes left,
* unless we're using DTLS1_BAD_VER, which has an extra 2 bytes
*/
if (n != 0) {
al = SSL_AD_ILLEGAL_PARAMETER;
SSLerr(SSL_F_SSL3_GET_CHANGE_CIPHER_SPEC, SSL_R_BAD_CHANGE_CIPHER_SPEC);
goto f_err;
if (SSL_IS_DTLS(s)) {
if ((s->version == DTLS1_BAD_VER && n != DTLS1_CCS_HEADER_LENGTH + 1)
|| (s->version != DTLS1_BAD_VER
&& n != DTLS1_CCS_HEADER_LENGTH - 1)) {
al = SSL_AD_ILLEGAL_PARAMETER;
SSLerr(SSL_F_SSL3_GET_CHANGE_CIPHER_SPEC, SSL_R_BAD_CHANGE_CIPHER_SPEC);
goto f_err;
}
} else {
if (n != 0) {
al = SSL_AD_ILLEGAL_PARAMETER;
SSLerr(SSL_F_SSL3_GET_CHANGE_CIPHER_SPEC, SSL_R_BAD_CHANGE_CIPHER_SPEC);
goto f_err;
}
}
/* Check we have a cipher to change to */
@ -262,6 +273,22 @@ int ssl3_get_change_cipher_spec(SSL *s, int a, int b)
goto f_err;
}
if (SSL_IS_DTLS(s)) {
dtls1_reset_seq_numbers(s, SSL3_CC_READ);
if (s->version == DTLS1_BAD_VER)
s->d1->handshake_read_seq++;
#ifndef OPENSSL_NO_SCTP
/*
* Remember that a CCS has been received, so that an old key of
* SCTP-Auth can be deleted when a CCS is sent. Will be ignored if no
* SCTP is used
*/
BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_AUTH_CCS_RCVD, 1, NULL);
#endif
}
return 1;
f_err:
ssl3_send_alert(s, SSL3_AL_FATAL, al);

5
ssl/ssl_locl.h
View file

@ -1437,11 +1437,6 @@ typedef struct dtls1_state_st {
unsigned short timeout_duration;
unsigned int retransmitting;
/*
* Set when the handshake is ready to process peer's ChangeCipherSpec message.
* Cleared after the message has been processed.
*/
unsigned int change_cipher_spec_ok;
# ifndef OPENSSL_NO_SCTP
/* used when SSL_ST_XX_FLUSH is entered */
int next_state;