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[pki] more ASN.1 parser improvements

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This commit is contained in:
Pete Batard 2017-09-05 22:21:34 +01:00
parent 94e4c0905b
commit 9464ae94a4
3 changed files with 43 additions and 29 deletions
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60
src/parser.c
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@ -1266,10 +1266,12 @@ char* replace_char(const char* src, const char c, const char* rep)
return res;
}
static void* get_data_from_asn1_internal(const uint8_t* buf, size_t buf_len, const void* oid,
size_t oid_len, uint8_t asn1_type, size_t* data_len, BOOL* matched)
/*
* Internal recursive call for get_data_from_asn1(). Returns FALSE on error, TRUE otherwise.
*/
static BOOL get_data_from_asn1_internal(const uint8_t* buf, size_t buf_len, const void* oid,
size_t oid_len, uint8_t asn1_type, void** data, size_t* data_len, BOOL* matched)
{
void* ret;
size_t pos = 0, len, len_len, i;
uint8_t tag;
BOOL is_sequence, is_universal_tag;
@ -1280,7 +1282,7 @@ static void* get_data_from_asn1_internal(const uint8_t* buf, size_t buf_len, con
tag = buf[pos++] & 0x1F;
if (tag == 0x1F) {
uprintf("get_data_from_asn1: Long form tags are unsupported");
return NULL;
return FALSE;
}
// Compute the length
@ -1294,7 +1296,7 @@ static void* get_data_from_asn1_internal(const uint8_t* buf, size_t buf_len, con
// The data we're dealing with is not expected to ever be larger than 64K
if (len_len > 2) {
uprintf("get_data_from_asn1: Length fields larger than 2 bytes are unsupported");
return NULL;
return FALSE;
}
for (i = 0; i < len_len; i++) {
len <<= 8;
@ -1306,51 +1308,57 @@ static void* get_data_from_asn1_internal(const uint8_t* buf, size_t buf_len, con
if (len > buf_len - pos) {
uprintf("get_data_from_asn1: Overflow error (computed length %d is larger than remaining data)", len);
return NULL;
return FALSE;
}
}
if (len != 0) {
if (is_sequence) {
ret = get_data_from_asn1_internal(&buf[pos], len, oid, oid_len, asn1_type, data_len, matched);
if (ret != NULL)
return ret;
if (!get_data_from_asn1_internal(&buf[pos], len, oid, oid_len, asn1_type, data, data_len, matched))
return FALSE; // error
if (*data != NULL)
return TRUE;
} else if (is_universal_tag) { // Only process tags that belong to the UNIVERSAL class
// NB: 0x06 = "OID" tag
if ((!*matched) && (tag == 0x06) && (len == oid_len) && (memcmp(&buf[pos], oid, oid_len) == 0)) {
*matched = TRUE;
} else if ((*matched) && (tag == asn1_type)) {
*data_len = len;
return (void*)&buf[pos];
*data = (void*)&buf[pos];
return TRUE;
}
}
pos += len;
}
};
return NULL;
return TRUE;
}
// Helper functions to convert an OID string to an OID byte array
// Taken from from openpgp-oid.c
static size_t make_flagged_int(unsigned long value, uint8_t *buf, size_t buflen)
/*
* Helper functions to convert an OID string to an OID byte array
* Taken from from openpgp-oid.c
*/
static size_t make_flagged_int(unsigned long value, uint8_t *buf, size_t buf_len)
{
BOOL more = FALSE;
int shift;
for (shift = 28; shift > 0; shift -= 7) {
if (more || value >= ((unsigned long)1 << shift)) {
buf[buflen++] = (uint8_t) (0x80 | (value >> shift));
buf[buf_len++] = (uint8_t) (0x80 | (value >> shift));
value -= (value >> shift) << shift;
more = TRUE;
}
}
buf[buflen++] = (uint8_t) value;
return buflen;
buf[buf_len++] = (uint8_t) value;
return buf_len;
}
// Convert OID string 'oid_str' to an OID byte array of size 'ret_len'
// The returned array must be freed by the caller.
/*
* Convert OID string 'oid_str' to an OID byte array of size 'ret_len'
* The returned array must be freed by the caller.
*/
static uint8_t* oid_from_str(const char* oid_str, size_t* ret_len)
{
uint8_t* oid = NULL;
@ -1414,21 +1422,27 @@ err:
*/
void* get_data_from_asn1(const uint8_t* buf, size_t buf_len, const char* oid_str, uint8_t asn1_type, size_t* data_len)
{
void* ret;
void* data = NULL;
uint8_t* oid = NULL;
size_t oid_len = 0;
BOOL matched = ((oid_str == NULL) || (oid_str[0] == 0));
if (buf_len >= 65536) {
uprintf("get_data_from_asn1: Buffers larger than 64KB are not supported");
return NULL;
}
if (!matched) {
// We have an OID string to convert
oid = oid_from_str(oid_str, &oid_len);
if (oid == NULL) {
uprintf("get_oid_data_from_asn1: Could not convert OID string '%s'", oid_str);
uprintf("get_data_from_asn1: Could not convert OID string '%s'", oid_str);
return NULL;
}
}
ret = get_data_from_asn1_internal(buf, buf_len, oid, oid_len, asn1_type, data_len, &matched);
// No need to check for the return value as data is always NULL on error
get_data_from_asn1_internal(buf, buf_len, oid, oid_len, asn1_type, &data, data_len, &matched);
free(oid);
return ret;
return data;
}