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/* Copyright (c) 2001 Matej Pfajfar.
* Copyright (c) 2001-2004, Roger Dingledine.
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2020, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* @file authcert_parse.c
* @brief Authority certificate parsing.
**/
#include "core/or/or.h"
#include "feature/dirparse/authcert_parse.h"
#include "feature/dirparse/parsecommon.h"
#include "feature/dirparse/sigcommon.h"
#include "feature/dirparse/unparseable.h"
#include "feature/nodelist/authcert.h"
#include "lib/memarea/memarea.h"
#include "feature/nodelist/authority_cert_st.h"
#include "feature/dirparse/authcert_members.h"
/** List of tokens recognized in V3 authority certificates. */
// clang-format off
static token_rule_t dir_key_certificate_table[] = {
AUTHCERT_MEMBERS,
T1("fingerprint", K_FINGERPRINT, CONCAT_ARGS, NO_OBJ ),
END_OF_TABLE
};
// clang-format on
/** Parse a key certificate from <b>s</b>; point <b>end-of-string</b> to
* the first character after the certificate. */
authority_cert_t *
authority_cert_parse_from_string(const char *s, size_t maxlen,
const char **end_of_string)
{
/** Reject any certificate at least this big; it is probably an overflow, an
* attack, a bug, or some other nonsense. */
#define MAX_CERT_SIZE (128*1024)
authority_cert_t *cert = NULL, *old_cert;
smartlist_t *tokens = NULL;
char digest[DIGEST_LEN];
directory_token_t *tok;
char fp_declared[DIGEST_LEN];
const char *eos;
size_t len;
int found;
memarea_t *area = NULL;
const char *end_of_s = s + maxlen;
const char *s_dup = s;
s = eat_whitespace_eos(s, end_of_s);
eos = tor_memstr(s, end_of_s - s, "\ndir-key-certification");
if (! eos) {
log_warn(LD_DIR, "No signature found on key certificate");
return NULL;
}
eos = tor_memstr(eos, end_of_s - eos, "\n-----END SIGNATURE-----\n");
if (! eos) {
log_warn(LD_DIR, "No end-of-signature found on key certificate");
return NULL;
}
eos = memchr(eos+2, '\n', end_of_s - (eos+2));
tor_assert(eos);
++eos;
len = eos - s;
if (len > MAX_CERT_SIZE) {
log_warn(LD_DIR, "Certificate is far too big (at %lu bytes long); "
"rejecting", (unsigned long)len);
return NULL;
}
tokens = smartlist_new();
area = memarea_new();
if (tokenize_string(area,s, eos, tokens, dir_key_certificate_table, 0) < 0) {
log_warn(LD_DIR, "Error tokenizing key certificate");
goto err;
}
if (router_get_hash_impl(s, eos - s, digest, "dir-key-certificate-version",
"\ndir-key-certification", '\n', DIGEST_SHA1) < 0)
goto err;
tok = smartlist_get(tokens, 0);
if (tok->tp != K_DIR_KEY_CERTIFICATE_VERSION || strcmp(tok->args[0], "3")) {
log_warn(LD_DIR,
"Key certificate does not begin with a recognized version (3).");
goto err;
}
cert = tor_malloc_zero(sizeof(authority_cert_t));
memcpy(cert->cache_info.signed_descriptor_digest, digest, DIGEST_LEN);
tok = find_by_keyword(tokens, K_DIR_SIGNING_KEY);
tor_assert(tok->key);
cert->signing_key = tok->key;
tok->key = NULL;
if (crypto_pk_get_digest(cert->signing_key, cert->signing_key_digest))
goto err;
tok = find_by_keyword(tokens, K_DIR_IDENTITY_KEY);
tor_assert(tok->key);
cert->identity_key = tok->key;
tok->key = NULL;
tok = find_by_keyword(tokens, K_FINGERPRINT);
tor_assert(tok->n_args);
if (base16_decode(fp_declared, DIGEST_LEN, tok->args[0],
strlen(tok->args[0])) != DIGEST_LEN) {
log_warn(LD_DIR, "Couldn't decode key certificate fingerprint %s",
escaped(tok->args[0]));
goto err;
}
if (crypto_pk_get_digest(cert->identity_key,
cert->cache_info.identity_digest))
goto err;
if (tor_memneq(cert->cache_info.identity_digest, fp_declared, DIGEST_LEN)) {
log_warn(LD_DIR, "Digest of certificate key didn't match declared "
"fingerprint");
goto err;
}
tok = find_opt_by_keyword(tokens, K_DIR_ADDRESS);
if (tok) {
struct in_addr in;
char *address = NULL;
tor_assert(tok->n_args);
/* XXX++ use some tor_addr parse function below instead. -RD */
if (tor_addr_port_split(LOG_WARN, tok->args[0], &address,
&cert->dir_port) < 0 ||
tor_inet_aton(address, &in) == 0) {
log_warn(LD_DIR, "Couldn't parse dir-address in certificate");
tor_free(address);
goto err;
}
cert->addr = ntohl(in.s_addr);
tor_free(address);
}
tok = find_by_keyword(tokens, K_DIR_KEY_PUBLISHED);
if (parse_iso_time(tok->args[0], &cert->cache_info.published_on) < 0) {
goto err;
}
tok = find_by_keyword(tokens, K_DIR_KEY_EXPIRES);
if (parse_iso_time(tok->args[0], &cert->expires) < 0) {
goto err;
}
tok = smartlist_get(tokens, smartlist_len(tokens)-1);
if (tok->tp != K_DIR_KEY_CERTIFICATION) {
log_warn(LD_DIR, "Certificate didn't end with dir-key-certification.");
goto err;
}
/* If we already have this cert, don't bother checking the signature. */
old_cert = authority_cert_get_by_digests(
cert->cache_info.identity_digest,
cert->signing_key_digest);
found = 0;
if (old_cert) {
/* XXXX We could just compare signed_descriptor_digest, but that wouldn't
* buy us much. */
if (old_cert->cache_info.signed_descriptor_len == len &&
old_cert->cache_info.signed_descriptor_body &&
tor_memeq(s, old_cert->cache_info.signed_descriptor_body, len)) {
log_debug(LD_DIR, "We already checked the signature on this "
"certificate; no need to do so again.");
found = 1;
}
}
if (!found) {
if (check_signature_token(digest, DIGEST_LEN, tok, cert->identity_key, 0,
"key certificate")) {
goto err;
}
tok = find_by_keyword(tokens, K_DIR_KEY_CROSSCERT);
if (check_signature_token(cert->cache_info.identity_digest,
DIGEST_LEN,
tok,
cert->signing_key,
CST_NO_CHECK_OBJTYPE,
"key cross-certification")) {
goto err;
}
}
cert->cache_info.signed_descriptor_len = len;
cert->cache_info.signed_descriptor_body = tor_malloc(len+1);
memcpy(cert->cache_info.signed_descriptor_body, s, len);
cert->cache_info.signed_descriptor_body[len] = 0;
cert->cache_info.saved_location = SAVED_NOWHERE;
if (end_of_string) {
*end_of_string = eat_whitespace(eos);
}
SMARTLIST_FOREACH(tokens, directory_token_t *, t, token_clear(t));
smartlist_free(tokens);
if (area) {
DUMP_AREA(area, "authority cert");
memarea_drop_all(area);
}
return cert;
err:
dump_desc(s_dup, "authority cert");
authority_cert_free(cert);
SMARTLIST_FOREACH(tokens, directory_token_t *, t, token_clear(t));
smartlist_free(tokens);
if (area) {
DUMP_AREA(area, "authority cert");
memarea_drop_all(area);
}
return NULL;
}
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