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Address feedback on SSLv2 ClientHello processing

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Feedback on the previous SSLv2 ClientHello processing fix was that it
breaks layering by reading init_num in the record layer. It also does not
detect if there was a previous non-fatal warning.

This is an alternative approach that directly tracks in the record layer
whether this is the first record.

GitHub Issue #1298

Reviewed-by: Tim Hudson <tjh@openssl.org>
This commit is contained in:
Matt Caswell 2016-08-01 17:15:13 +01:00
parent c35d339d98
commit 44efb88a21
4 changed files with 13 additions and 7 deletions
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1
ssl/record/rec_layer_s3.c
View file

@ -33,6 +33,7 @@
void RECORD_LAYER_init(RECORD_LAYER *rl, SSL *s)
{
rl->s = s;
RECORD_LAYER_set_first_record(&s->rlayer, 1);
SSL3_RECORD_clear(rl->rrec, SSL_MAX_PIPELINES);
}

3
ssl/record/record.h
View file

@ -199,6 +199,9 @@ typedef struct record_layer_st {
unsigned char read_sequence[SEQ_NUM_SIZE];
unsigned char write_sequence[SEQ_NUM_SIZE];
/* Set to true if this is the first record in a connection */
unsigned int is_first_record;
DTLS_RECORD_LAYER *d;
} RECORD_LAYER;

2
ssl/record/record_locl.h
View file

@ -31,6 +31,8 @@
#define RECORD_LAYER_reset_empty_record_count(rl) \
((rl)->empty_record_count = 0)
#define RECORD_LAYER_get_empty_record_count(rl) ((rl)->empty_record_count)
#define RECORD_LAYER_is_first_record(rl) ((rl)->is_first_record)
#define RECORD_LAYER_set_first_record(rl, val) ((rl)->is_first_record = (val))
#define DTLS_RECORD_LAYER_get_r_epoch(rl) ((rl)->d->r_epoch)
__owur int ssl3_read_n(SSL *s, int n, int max, int extend, int clearold);

14
ssl/record/ssl3_record.c
View file

@ -162,15 +162,14 @@ int ssl3_get_record(SSL *s)
* Check whether this is a regular record or an SSLv2 style record.
* The latter can only be used in the first record of an initial
* ClientHello for old clients. Initial ClientHello means
* s->first_packet is set and s->server is true. The first record
* means we've not received any data so far (s->init_num == 0) and
* have had no empty records. We check s->read_hash and
* s->enc_read_ctx to ensure this does not apply during
* renegotiation.
* s->first_packet is set and s->server is true. The first record
* means s->rlayer.is_first_record is true. Probably this is
* sufficient in itself instead of s->first_packet, but I am
* cautious. We check s->read_hash and s->enc_read_ctx to ensure
* this does not apply during renegotiation.
*/
if (s->first_packet && s->server
&& s->init_num == 0
&& RECORD_LAYER_get_empty_record_count(&s->rlayer) == 0
&& RECORD_LAYER_is_first_record(&s->rlayer)
&& s->read_hash == NULL && s->enc_read_ctx == NULL
&& (p[0] & 0x80) && (p[2] == SSL2_MT_CLIENT_HELLO)) {
/*
@ -335,6 +334,7 @@ int ssl3_get_record(SSL *s)
/* we have pulled in a full packet so zero things */
RECORD_LAYER_reset_packet_length(&s->rlayer);
RECORD_LAYER_set_first_record(&s->rlayer, 0);
} while (num_recs < max_recs
&& rr[num_recs-1].type == SSL3_RT_APPLICATION_DATA
&& SSL_USE_EXPLICIT_IV(s)