Commit message: Fix Seg fault in DTLSv1_listen

The DTLSv1_listen function is intended to be stateless and processes
the initial ClientHello from many peers. It is common for user code to
loop over the call to DTLSv1_listen until a valid ClientHello is received
with an associated cookie. A defect in the implementation of DTLSv1_listen
means that state is preserved in the SSL object from one invokation to the
next that can lead to a segmentation fault. Erorrs processing the initial
ClientHello can trigger this scenario. An example of such an error could
be that a DTLS1.0 only client is attempting to connect to a DTLS1.2 only
server.

CVE-2015-0207

Reviewed-by: Richard Levitte <levitte@openssl.org>
CVE: CVE-2015-0207
CWE: NVD-CWE-Other
Vulnerability description: The dtls1_listen function in d1_lib.c in OpenSSL 1.0.2 before 1.0.2a does not properly isolate the state information of independent data streams, which allows remote attackers to cause a denial of service (application crash) via crafted DTLS traffic, as demonstrated by DTLS 1.0 traffic to a DTLS 1.2 server.

Project: openssl

int dtls1_check_timeout_num(SSL *s)
{
    unsigned int mtu;

    s->d1->timeout.num_alerts++;

    /* Reduce MTU after 2 unsuccessful retransmissions */
    if (s->d1->timeout.num_alerts > 2
        && !(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) {
        mtu =
            BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0,
                     NULL);
        if (mtu < s->d1->mtu)
            s->d1->mtu = mtu;
    }

    if (s->d1->timeout.num_alerts > DTLS1_TMO_ALERT_COUNT) {
        /* fail the connection, enough alerts have been sent */
        SSLerr(SSL_F_DTLS1_CHECK_TIMEOUT_NUM, SSL_R_READ_TIMEOUT_EXPIRED);
        return -1;
    }

    return 0;
}

Project: openssl

void dtls1_clear(SSL *s)
{
    pqueue unprocessed_rcds;
    pqueue processed_rcds;
    pqueue buffered_messages;
    pqueue sent_messages;
    pqueue buffered_app_data;
    unsigned int mtu;
    unsigned int link_mtu;

    if (s->d1) {
        unprocessed_rcds = s->d1->unprocessed_rcds.q;
        processed_rcds = s->d1->processed_rcds.q;
        buffered_messages = s->d1->buffered_messages;
        sent_messages = s->d1->sent_messages;
        buffered_app_data = s->d1->buffered_app_data.q;
        mtu = s->d1->mtu;
        link_mtu = s->d1->link_mtu;

        dtls1_clear_queues(s);

        memset(s->d1, 0, sizeof(*(s->d1)));

        if (s->server) {
            s->d1->cookie_len = sizeof(s->d1->cookie);
        }

        if (SSL_get_options(s) & SSL_OP_NO_QUERY_MTU) {
            s->d1->mtu = mtu;
            s->d1->link_mtu = link_mtu;
        }

        s->d1->unprocessed_rcds.q = unprocessed_rcds;
        s->d1->processed_rcds.q = processed_rcds;
        s->d1->buffered_messages = buffered_messages;
        s->d1->sent_messages = sent_messages;
        s->d1->buffered_app_data.q = buffered_app_data;
    }

    ssl3_clear(s);
    if (s->options & SSL_OP_CISCO_ANYCONNECT)
        s->client_version = s->version = DTLS1_BAD_VER;
    else if (s->method->version == DTLS_ANY_VERSION)
        s->version = DTLS1_2_VERSION;
    else
        s->version = s->method->version;
}

Project: openssl

static void dtls1_clear_queues(SSL *s)
{
    pitem *item = NULL;
    hm_fragment *frag = NULL;
    DTLS1_RECORD_DATA *rdata;

    while ((item = pqueue_pop(s->d1->unprocessed_rcds.q)) != NULL) {
        rdata = (DTLS1_RECORD_DATA *)item->data;
        if (rdata->rbuf.buf) {
            OPENSSL_free(rdata->rbuf.buf);
        }
        OPENSSL_free(item->data);
        pitem_free(item);
    }

    while ((item = pqueue_pop(s->d1->processed_rcds.q)) != NULL) {
        rdata = (DTLS1_RECORD_DATA *)item->data;
        if (rdata->rbuf.buf) {
            OPENSSL_free(rdata->rbuf.buf);
        }
        OPENSSL_free(item->data);
        pitem_free(item);
    }

    while ((item = pqueue_pop(s->d1->buffered_messages)) != NULL) {
        frag = (hm_fragment *)item->data;
        dtls1_hm_fragment_free(frag);
        pitem_free(item);
    }

    while ((item = pqueue_pop(s->d1->sent_messages)) != NULL) {
        frag = (hm_fragment *)item->data;
        dtls1_hm_fragment_free(frag);
        pitem_free(item);
    }

    while ((item = pqueue_pop(s->d1->buffered_app_data.q)) != NULL) {
        rdata = (DTLS1_RECORD_DATA *)item->data;
        if (rdata->rbuf.buf) {
            OPENSSL_free(rdata->rbuf.buf);
        }
        OPENSSL_free(item->data);
        pitem_free(item);
    }
}

Project: openssl

long dtls1_ctrl(SSL *s, int cmd, long larg, void *parg)
{
    int ret = 0;

    switch (cmd) {
    case DTLS_CTRL_GET_TIMEOUT:
        if (dtls1_get_timeout(s, (struct timeval *)parg) != NULL) {
            ret = 1;
        }
        break;
    case DTLS_CTRL_HANDLE_TIMEOUT:
        ret = dtls1_handle_timeout(s);
        break;
    case DTLS_CTRL_LISTEN:
        ret = dtls1_listen(s, parg);
        break;
    case SSL_CTRL_CHECK_PROTO_VERSION:
        /*
         * For library-internal use; checks that the current protocol is the
         * highest enabled version (according to s->ctx->method, as version
         * negotiation may have changed s->method).
         */
        if (s->version == s->ctx->method->version)
            return 1;
        /*
         * Apparently we're using a version-flexible SSL_METHOD (not at its
         * highest protocol version).
         */
        if (s->ctx->method->version == DTLS_method()->version) {
#if DTLS_MAX_VERSION != DTLS1_2_VERSION
# error Code needs update for DTLS_method() support beyond DTLS1_2_VERSION.
#endif
            if (!(s->options & SSL_OP_NO_DTLSv1_2))
                return s->version == DTLS1_2_VERSION;
            if (!(s->options & SSL_OP_NO_DTLSv1))
                return s->version == DTLS1_VERSION;
        }
        return 0;               /* Unexpected state; fail closed. */
    case DTLS_CTRL_SET_LINK_MTU:
        if (larg < (long)dtls1_link_min_mtu())
            return 0;
        s->d1->link_mtu = larg;
        return 1;
    case DTLS_CTRL_GET_LINK_MIN_MTU:
        return (long)dtls1_link_min_mtu();
    case SSL_CTRL_SET_MTU:
        /*
         *  We may not have a BIO set yet so can't call dtls1_min_mtu()
         *  We'll have to make do with dtls1_link_min_mtu() and max overhead
         */
        if (larg < (long)dtls1_link_min_mtu() - DTLS1_MAX_MTU_OVERHEAD)
            return 0;
        s->d1->mtu = larg;
        return larg;
    default:
        ret = ssl3_ctrl(s, cmd, larg, parg);
        break;
    }
    return (ret);
}

Project: openssl

long dtls1_default_timeout(void)
{
    /*
     * 2 hours, the 24 hours mentioned in the DTLSv1 spec is way too long for
     * http, the cache would over fill
     */
    return (60 * 60 * 2);
}

Project: openssl

void dtls1_double_timeout(SSL *s)
{
    s->d1->timeout_duration *= 2;
    if (s->d1->timeout_duration > 60)
        s->d1->timeout_duration = 60;
    dtls1_start_timer(s);
}

Project: openssl

void dtls1_free(SSL *s)
{
    ssl3_free(s);

    dtls1_clear_queues(s);

    pqueue_free(s->d1->unprocessed_rcds.q);
    pqueue_free(s->d1->processed_rcds.q);
    pqueue_free(s->d1->buffered_messages);
    pqueue_free(s->d1->sent_messages);
    pqueue_free(s->d1->buffered_app_data.q);

    OPENSSL_free(s->d1);
    s->d1 = NULL;
}

Project: openssl

const SSL_CIPHER *dtls1_get_cipher(unsigned int u)
{
    const SSL_CIPHER *ciph = ssl3_get_cipher(u);

    if (ciph != NULL) {
        if (ciph->algorithm_enc == SSL_RC4)
            return NULL;
    }

    return ciph;
}

Project: openssl

struct timeval *dtls1_get_timeout(SSL *s, struct timeval *timeleft)
{
    struct timeval timenow;

    /* If no timeout is set, just return NULL */
    if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
        return NULL;
    }

    /* Get current time */
    get_current_time(&timenow);

    /* If timer already expired, set remaining time to 0 */
    if (s->d1->next_timeout.tv_sec < timenow.tv_sec ||
        (s->d1->next_timeout.tv_sec == timenow.tv_sec &&
         s->d1->next_timeout.tv_usec <= timenow.tv_usec)) {
        memset(timeleft, 0, sizeof(struct timeval));
        return timeleft;
    }

    /* Calculate time left until timer expires */
    memcpy(timeleft, &(s->d1->next_timeout), sizeof(struct timeval));
    timeleft->tv_sec -= timenow.tv_sec;
    timeleft->tv_usec -= timenow.tv_usec;
    if (timeleft->tv_usec < 0) {
        timeleft->tv_sec--;
        timeleft->tv_usec += 1000000;
    }

    /*
     * If remaining time is less than 15 ms, set it to 0 to prevent issues
     * because of small devergences with socket timeouts.
     */
    if (timeleft->tv_sec == 0 && timeleft->tv_usec < 15000) {
        memset(timeleft, 0, sizeof(struct timeval));
    }

    return timeleft;
}

Project: openssl

int dtls1_handle_timeout(SSL *s)
{
    /* if no timer is expired, don't do anything */
    if (!dtls1_is_timer_expired(s)) {
        return 0;
    }

    dtls1_double_timeout(s);

    if (dtls1_check_timeout_num(s) < 0)
        return -1;

    s->d1->timeout.read_timeouts++;
    if (s->d1->timeout.read_timeouts > DTLS1_TMO_READ_COUNT) {
        s->d1->timeout.read_timeouts = 1;
    }
#ifndef OPENSSL_NO_HEARTBEATS
    if (s->tlsext_hb_pending) {
        s->tlsext_hb_pending = 0;
        return dtls1_heartbeat(s);
    }
#endif

    dtls1_start_timer(s);
    return dtls1_retransmit_buffered_messages(s);
}

Project: openssl

static int dtls1_handshake_write(SSL *s)
{
    return dtls1_do_write(s, SSL3_RT_HANDSHAKE);
}

Project: openssl

int dtls1_is_timer_expired(SSL *s)
{
    struct timeval timeleft;

    /* Get time left until timeout, return false if no timer running */
    if (dtls1_get_timeout(s, &timeleft) == NULL) {
        return 0;
    }

    /* Return false if timer is not expired yet */
    if (timeleft.tv_sec > 0 || timeleft.tv_usec > 0) {
        return 0;
    }

    /* Timer expired, so return true */
    return 1;
}

Project: openssl

int dtls1_new(SSL *s)
{
    DTLS1_STATE *d1;

    if (!ssl3_new(s))
        return (0);
    if ((d1 = OPENSSL_malloc(sizeof *d1)) == NULL)
        return (0);
    memset(d1, 0, sizeof *d1);

    /* d1->handshake_epoch=0; */

    d1->unprocessed_rcds.q = pqueue_new();
    d1->processed_rcds.q = pqueue_new();
    d1->buffered_messages = pqueue_new();
    d1->sent_messages = pqueue_new();
    d1->buffered_app_data.q = pqueue_new();

    if (s->server) {
        d1->cookie_len = sizeof(s->d1->cookie);
    }

    d1->link_mtu = 0;
    d1->mtu = 0;

    if (!d1->unprocessed_rcds.q || !d1->processed_rcds.q
        || !d1->buffered_messages || !d1->sent_messages
        || !d1->buffered_app_data.q) {
        if (d1->unprocessed_rcds.q)
            pqueue_free(d1->unprocessed_rcds.q);
        if (d1->processed_rcds.q)
            pqueue_free(d1->processed_rcds.q);
        if (d1->buffered_messages)
            pqueue_free(d1->buffered_messages);
        if (d1->sent_messages)
            pqueue_free(d1->sent_messages);
        if (d1->buffered_app_data.q)
            pqueue_free(d1->buffered_app_data.q);
        OPENSSL_free(d1);
        return (0);
    }

    s->d1 = d1;
    s->method->ssl_clear(s);
    return (1);
}

Project: openssl

static void dtls1_set_handshake_header(SSL *s, int htype, unsigned long len)
{
    unsigned char *p = (unsigned char *)s->init_buf->data;
    dtls1_set_message_header(s, p, htype, len, 0, len);
    s->init_num = (int)len + DTLS1_HM_HEADER_LENGTH;
    s->init_off = 0;
    /* Buffer the message to handle re-xmits */
    dtls1_buffer_message(s, 0);
}

Project: openssl

void dtls1_start_timer(SSL *s)
{
#ifndef OPENSSL_NO_SCTP
    /* Disable timer for SCTP */
    if (BIO_dgram_is_sctp(SSL_get_wbio(s))) {
        memset(&(s->d1->next_timeout), 0, sizeof(struct timeval));
        return;
    }
#endif

    /* If timer is not set, initialize duration with 1 second */
    if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
        s->d1->timeout_duration = 1;
    }

    /* Set timeout to current time */
    get_current_time(&(s->d1->next_timeout));

    /* Add duration to current time */
    s->d1->next_timeout.tv_sec += s->d1->timeout_duration;
    BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
             &(s->d1->next_timeout));
}

Project: openssl

void dtls1_stop_timer(SSL *s)
{
    /* Reset everything */
    memset(&(s->d1->timeout), 0, sizeof(struct dtls1_timeout_st));
    memset(&(s->d1->next_timeout), 0, sizeof(struct timeval));
    s->d1->timeout_duration = 1;
    BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
             &(s->d1->next_timeout));
    /* Clear retransmission buffer */
    dtls1_clear_record_buffer(s);
}

Project: openssl

static void get_current_time(struct timeval *t)
{
#if defined(_WIN32)
    SYSTEMTIME st;
    union {
        unsigned __int64 ul;
        FILETIME ft;
    } now;

    GetSystemTime(&st);
    SystemTimeToFileTime(&st, &now.ft);
# ifdef  __MINGW32__
    now.ul -= 116444736000000000ULL;
# else
    now.ul -= 116444736000000000UI64; /* re-bias to 1/1/1970 */
# endif
    t->tv_sec = (long)(now.ul / 10000000);
    t->tv_usec = ((int)(now.ul % 10000000)) / 10;
#elif defined(OPENSSL_SYS_VMS)
    struct timeb tb;
    ftime(&tb);
    t->tv_sec = (long)tb.time;
    t->tv_usec = (long)tb.millitm * 1000;
#else
    gettimeofday(t, NULL);
#endif
}