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Use sc_asn1_read_tag to read first tag of partially block (#1454) 

Sc_asn1_read_tag can return SC_ERROR_ASN1_END_OF_CONTENTS
which indicates the tag and length are OK, but any value
is not completely contained in the buffer supplied. card-piv.c
can use this when reading just the beginning of a object to
determine the size of a buffer needed to hold the object.
This commit is contained in:
Doug Engert 2018-08-23 13:35:24 -05:00 committed by Frank Morgner
parent 97f0a341b0
commit 719ec39b3e
1 changed files with 13 additions and 12 deletions
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25
src/libopensc/card-piv.c
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@ -479,6 +479,7 @@ static int piv_general_io(sc_card_t *card, int ins, int p1, int p2,
size_t * recvbuflen)
{
int r;
int r_tag ;
sc_apdu_t apdu;
u8 rbufinitbuf[4096];
u8 *rbuf;
@ -572,16 +573,12 @@ static int piv_general_io(sc_card_t *card, int ins, int p1, int p2,
* the buffer is bigger, so it will not produce "ASN1.tag too long!" */
body = rbuf;
if (sc_asn1_read_tag(&body, rbuflen, &cla_out, &tag_out, &bodylen) != SC_SUCCESS
r_tag = sc_asn1_read_tag(&body, apdu.resplen, &cla_out, &tag_out, &bodylen);
sc_log(card->ctx, "r_tag:%d body:%p", r_tag, body);
if ( (r_tag != SC_SUCCESS && r_tag != SC_ERROR_ASN1_END_OF_CONTENTS)
|| body == NULL) {
/* only early beta cards had this problem */
sc_log(card->ctx, "***** received buffer tag MISSING ");
body = rbuf;
/* some readers/cards might return 6c 00 */
if (apdu.sw1 == 0x61 || apdu.sw2 == 0x6c )
bodylen = 12000;
else
bodylen = apdu.resplen;
bodylen = apdu.resplen;
}
rbuflen = body - rbuf + bodylen;
@ -856,6 +853,7 @@ static int piv_read_obj_from_file(sc_card_t * card, char * filename,
u8 **buf, size_t *buf_len)
{
int r;
int r_tag;
int f = -1;
size_t len;
u8 tagbuf[16];
@ -881,10 +879,11 @@ static int piv_read_obj_from_file(sc_card_t * card, char * filename,
goto err;
}
body = tagbuf;
if (sc_asn1_read_tag(&body, 0xfffff, &cla_out, &tag_out, &bodylen) != SC_SUCCESS
r_tag = sc_asn1_read_tag(&body, len, &cla_out, &tag_out, &bodylen);
if ((r_tag != SC_SUCCESS && r_tag != SC_ERROR_ASN1_END_OF_CONTENTS)
|| body == NULL) {
sc_log(card->ctx, "DER problem");
r = SC_ERROR_INVALID_ASN1_OBJECT;
r = SC_ERROR_FILE_NOT_FOUND;
goto err;
}
rbuflen = body - tagbuf + bodylen;
@ -947,10 +946,12 @@ piv_get_data(sc_card_t * card, int enumtag, u8 **buf, size_t *buf_len)
rbuflen = sizeof(rbufinitbuf);
r = piv_general_io(card, 0xCB, 0x3F, 0xFF, tagbuf, p - tagbuf, &rbuf, &rbuflen);
if (r > 0) {
int r_tag;
body = rbuf;
if (sc_asn1_read_tag(&body, 0xffff, &cla_out, &tag_out, &bodylen) != SC_SUCCESS
r_tag = sc_asn1_read_tag(&body, rbuflen, &cla_out, &tag_out, &bodylen);
if ((r_tag != SC_SUCCESS && r_tag != SC_ERROR_ASN1_END_OF_CONTENTS)
|| body == NULL) {
sc_log(card->ctx, "***** received buffer tag MISSING ");
sc_log(card->ctx, "r_tag:%d body:%p", r_tag, body);
r = SC_ERROR_FILE_NOT_FOUND;
goto err;
}