Commit 22646a07 authored by Matt Caswell's avatar Matt Caswell
Browse files

Don't allow too many consecutive warning alerts 



Certain warning alerts are ignored if they are received. This can mean that
no progress will be made if one peer continually sends those warning alerts.
Implement a count so that we abort the connection if we receive too many.

Issue reported by Shi Lei.

Reviewed-by: default avatarRich Salz <rsalz@openssl.org>
parent 006a788c

ssl/d1_pkt.c

+15 −0
Original line number Diff line number Diff line
@@ -951,6 +951,13 @@ int dtls1_read_bytes(SSL *s, int type, unsigned char *buf, int len, int peek) 
        goto start;

    }



    /*

     * Reset the count of consecutive warning alerts if we've got a non-empty

     * record that isn't an alert.

     */

    if (rr->type != SSL3_RT_ALERT && rr->length != 0)

        s->cert->alert_count = 0;



    /* we now have a packet which can be read and processed */



    if (s->s3->change_cipher_spec /* set when we receive ChangeCipherSpec,
@@ -1217,6 +1224,14 @@ int dtls1_read_bytes(SSL *s, int type, unsigned char *buf, int len, int peek) 


        if (alert_level == SSL3_AL_WARNING) {

            s->s3->warn_alert = alert_descr;



            s->cert->alert_count++;

            if (s->cert->alert_count == MAX_WARN_ALERT_COUNT) {

                al = SSL_AD_UNEXPECTED_MESSAGE;

                SSLerr(SSL_F_DTLS1_READ_BYTES, SSL_R_TOO_MANY_WARN_ALERTS);

                goto f_err;

            }



            if (alert_descr == SSL_AD_CLOSE_NOTIFY) {

#ifndef OPENSSL_NO_SCTP

                /*

ssl/s3_pkt.c

+15 −0
Original line number Diff line number Diff line
@@ -1229,6 +1229,13 @@ int ssl3_read_bytes(SSL *s, int type, unsigned char *buf, int len, int peek) 
            return (ret);

    }



    /*

     * Reset the count of consecutive warning alerts if we've got a non-empty

     * record that isn't an alert.

     */

    if (rr->type != SSL3_RT_ALERT && rr->length != 0)

        s->cert->alert_count = 0;



    /* we now have a packet which can be read and processed */



    if (s->s3->change_cipher_spec /* set when we receive ChangeCipherSpec,
@@ -1443,6 +1450,14 @@ int ssl3_read_bytes(SSL *s, int type, unsigned char *buf, int len, int peek) 


        if (alert_level == SSL3_AL_WARNING) {

            s->s3->warn_alert = alert_descr;



            s->cert->alert_count++;

            if (s->cert->alert_count == MAX_WARN_ALERT_COUNT) {

                al = SSL_AD_UNEXPECTED_MESSAGE;

                SSLerr(SSL_F_SSL3_READ_BYTES, SSL_R_TOO_MANY_WARN_ALERTS);

                goto f_err;

            }



            if (alert_descr == SSL_AD_CLOSE_NOTIFY) {

                s->shutdown |= SSL_RECEIVED_SHUTDOWN;

                return (0);

ssl/ssl.h

+1 −0
Original line number Diff line number Diff line
@@ -3107,6 +3107,7 @@ void ERR_load_SSL_strings(void); 
# define SSL_R_TLS_INVALID_ECPOINTFORMAT_LIST             157

# define SSL_R_TLS_PEER_DID_NOT_RESPOND_WITH_CERTIFICATE_LIST 233

# define SSL_R_TLS_RSA_ENCRYPTED_VALUE_LENGTH_IS_WRONG    234

# define SSL_R_TOO_MANY_WARN_ALERTS                       409

# define SSL_R_TRIED_TO_USE_UNSUPPORTED_CIPHER            235

# define SSL_R_UNABLE_TO_DECODE_DH_CERTS                  236

# define SSL_R_UNABLE_TO_DECODE_ECDH_CERTS                313

ssl/ssl_locl.h

+4 −0
Original line number Diff line number Diff line
@@ -591,6 +591,8 @@ typedef struct { 
 */

# define SSL_EXT_FLAG_SENT       0x2



# define MAX_WARN_ALERT_COUNT    5



typedef struct {

    custom_ext_method *meths;

    size_t meths_count;
@@ -698,6 +700,8 @@ typedef struct cert_st { 
    unsigned char *alpn_proposed;   /* server */

    unsigned int alpn_proposed_len;

    int alpn_sent;                  /* client */

    /* Count of the number of consecutive warning alerts received */

    unsigned int alert_count;

} CERT;



typedef struct sess_cert_st {