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/*
* Part of DNS zone file validator `validns`.
*
* Copyright 2011-2014 Anton Berezin <tobez@tobez.org>
* Modified BSD license.
* (See LICENSE file in the distribution.)
*
*/
#include <sys/types.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <openssl/bn.h>
#include <openssl/evp.h>
#include <openssl/rsa.h>
#include "common.h"
#include "textparse.h"
#include "mempool.h"
#include "carp.h"
#include "rr.h"
static struct rr_dnskey *all_dns_keys = NULL;
static struct rr* dnskey_parse(char *name, long ttl, int type, char *s)
{
struct rr_dnskey *rr = getmem(sizeof(*rr));
struct binary_data key;
int flags, proto, algorithm;
unsigned int ac;
int i;
static struct rr *result;
flags = extract_integer(&s, "flags", NULL);
if (flags < 0) return NULL;
if (flags & 0xfe7e)
return bitch("reserved flags bits are set");
if (flags & 0x0001 && !(flags & 0x0100))
return bitch("SEP bit is set but Zone Key bit is unset");
rr->flags = flags;
/* TODO validate that `name` is the name of the zone if flags have Zone Key bit set */
proto = extract_integer(&s, "protocol", NULL);
if (proto < 0) return NULL;
if (proto != 3)
return bitch("bad protocol value");
rr->protocol = proto;
algorithm = extract_algorithm(&s, "algorithm");
if (algorithm == ALG_UNSUPPORTED) return NULL;
if (algorithm == ALG_PRIVATEDNS || algorithm == ALG_PRIVATEOID) {
return bitch("private algorithms are not supported in DNSKEY");
}
rr->algorithm = algorithm;
key = extract_base64_binary_data(&s, "public key");
if (key.length < 0) return NULL;
/* TODO validate key length based on algorithm */
rr->pubkey = key;
ac = 0;
ac += rr->flags;
ac += rr->protocol << 8;
ac += rr->algorithm;
for (i = 0; i < rr->pubkey.length; i++) {
ac += (i & 1) ? (unsigned char)rr->pubkey.data[i] : ((unsigned char)rr->pubkey.data[i]) << 8;
}
ac += (ac >> 16) & 0xFFFF;
rr->key_tag = ac & 0xFFFF;
rr->pkey_built = 0;
rr->pkey = NULL;
rr->key_type = KEY_TYPE_UNUSED;
if (*s) {
return bitch("garbage after valid DNSKEY data");
}
result = store_record(type, name, ttl, rr);
if (result) {
rr->next_key = all_dns_keys;
all_dns_keys = rr;
}
return result;
}
static char* dnskey_human(struct rr *rrv)
{
RRCAST(dnskey);
char s[1024];
snprintf(s, 1024, "%hu %d %d XXX ; key id = %hu",
rr->flags, rr->protocol, rr->algorithm, rr->key_tag);
return quickstrdup_temp(s);
}
static struct binary_data dnskey_wirerdata(struct rr *rrv)
{
RRCAST(dnskey);
return compose_binary_data("211d", 1,
rr->flags, rr->protocol, rr->algorithm,
rr->pubkey);
}
static void *dnskey_validate(struct rr *rrv)
{
RRCAST(dnskey);
if (G.opt.policy_checks[POLICY_DNSKEY]) {
if (algorithm_type(rr->algorithm) == ALG_RSA_FAMILY) {
unsigned int e_bytes;
unsigned char *pk;
int l;
pk = (unsigned char *)rr->pubkey.data;
l = rr->pubkey.length;
e_bytes = *pk++;
l--;
if (e_bytes == 0) {
if (l < 2)
return moan(rr->rr.file_name, rr->rr.line, "public key is too short");
e_bytes = (*pk++) << 8;
e_bytes += *pk++;
l -= 2;
}
if (l < e_bytes)
return moan(rr->rr.file_name, rr->rr.line, "public key is too short");
if (*pk == 0)
return moan(rr->rr.file_name, rr->rr.line, "leading zero octets in public key exponent");
pk += e_bytes;
l -= e_bytes;
if (l > 0 && *pk == 0)
return moan(rr->rr.file_name, rr->rr.line, "leading zero octets in key modulus");
}
}
return NULL;
}
struct rr_methods dnskey_methods = { dnskey_parse, dnskey_human, dnskey_wirerdata, NULL, dnskey_validate };
int dnskey_build_pkey(struct rr_dnskey *rr)
{
if (rr->pkey_built)
return rr->pkey ? 1 : 0;
rr->pkey_built = 1;
if (algorithm_type(rr->algorithm) == ALG_RSA_FAMILY) {
RSA *rsa;
EVP_PKEY *pkey;
unsigned int e_bytes;
unsigned char *pk;
int l;
BIGNUM *n, *e;
rsa = RSA_new();
if (!rsa)
goto done;
pk = (unsigned char *)rr->pubkey.data;
l = rr->pubkey.length;
e_bytes = *pk++;
l--;
if (e_bytes == 0) {
if (l < 2) /* public key is too short */
goto done;
e_bytes = (*pk++) << 8;
e_bytes += *pk++;
l -= 2;
}
if (l < e_bytes) /* public key is too short */
goto done;
e = BN_bin2bn(pk, e_bytes, NULL);
pk += e_bytes;
l -= e_bytes;
n = BN_bin2bn(pk, l, NULL);
if (!e || !n)
goto done;
RSA_set0_key(rsa, n, e, NULL);
pkey = EVP_PKEY_new();
if (!pkey)
goto done;
if (!EVP_PKEY_set1_RSA(pkey, rsa))
goto done;
rr->pkey = pkey;
}
done:
if (!rr->pkey) {
moan(rr->rr.file_name, rr->rr.line, "error building pkey");
}
return rr->pkey ? 1 : 0;
}
void
dnskey_ksk_policy_check(void)
{
struct rr_dnskey *rr = all_dns_keys;
int ksk_found = 0;
while (rr) {
if (rr->key_type == KEY_TYPE_KSK)
ksk_found = 1;
rr = rr->next_key;
}
if (!ksk_found)
moan(all_dns_keys->rr.file_name, all_dns_keys->rr.line, "No KSK found");
}
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