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Refactor dirobj signature generation

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Now we can compute the hash and signature of a dirobj before
concatenating the smartlist, and we don't need to play silly games
with sigbuf and realloc any more.
This commit is contained in:
Nick Mathewson 2013-02-22 12:53:45 -05:00
parent fd93622cc8
commit cb75519bbf
7 changed files with 122 additions and 85 deletions
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23
src/common/crypto.c
View File

@ -1631,6 +1631,29 @@ crypto_digest_assign(crypto_digest_t *into,
memcpy(into,from,sizeof(crypto_digest_t));
}
/** Given a list of strings in <b>lst</b>, set the <b>len_out</b>-byte digest
* at <b>digest_out</b> to the hash of the concatenation of those strings,
* plus the optional string <b>append</b>, computed with the algorithm
* <b>alg</b>. */
void
crypto_digest_smartlist(char *digest_out, size_t len_out,
const smartlist_t *lst, const char *append,
digest_algorithm_t alg)
{
crypto_digest_t *d;
if (alg == DIGEST_SHA1)
d = crypto_digest_new();
else
d = crypto_digest256_new(alg);
SMARTLIST_FOREACH(lst, const char *, cp,
crypto_digest_add_bytes(d, cp, strlen(cp)));
if (append)
crypto_digest_add_bytes(d, append, strlen(append));
crypto_digest_get_digest(d, digest_out, len_out);
crypto_digest_free(d);
}
/** Compute the HMAC-SHA-1 of the <b>msg_len</b> bytes in <b>msg</b>, using
* the <b>key</b> of length <b>key_len</b>. Store the DIGEST_LEN-byte result
* in <b>hmac_out</b>.

4
src/common/crypto.h
View File

@ -206,6 +206,10 @@ int crypto_digest(char *digest, const char *m, size_t len);
int crypto_digest256(char *digest, const char *m, size_t len,
digest_algorithm_t algorithm);
int crypto_digest_all(digests_t *ds_out, const char *m, size_t len);
struct smartlist_t;
void crypto_digest_smartlist(char *digest_out, size_t len_out,
const struct smartlist_t *lst, const char *append,
digest_algorithm_t alg);
const char *crypto_digest_algorithm_get_name(digest_algorithm_t alg);
int crypto_digest_algorithm_parse_name(const char *name);
crypto_digest_t *crypto_digest_new(void);

21
src/or/dirserv.c
View File

@ -2911,7 +2911,6 @@ generate_v2_networkstatus_opinion(void)
size_t identity_pkey_len;
char *status = NULL, *client_versions = NULL, *server_versions = NULL,
*identity_pkey = NULL, *hostname = NULL;
size_t status_len;
const or_options_t *options = get_options();
char fingerprint[FINGERPRINT_LEN+1];
char published[ISO_TIME_LEN+1];
@ -3032,22 +3031,20 @@ generate_v2_networkstatus_opinion(void)
smartlist_add_asprintf(chunks, "directory-signature %s\n",
options->Nickname);
status = smartlist_join_strings(chunks, "", 0, NULL);
#define MAX_V2_OPINION_SIGNATURE_LEN 4096
status_len = strlen(status) + MAX_V2_OPINION_SIGNATURE_LEN + 1;
status = tor_realloc(status, status_len);
if (router_get_networkstatus_v2_hash(status, digest)<0) {
log_warn(LD_BUG, "Unable to hash network status");
goto done;
}
crypto_digest_smartlist(digest, DIGEST_LEN, chunks, "", DIGEST_SHA1);
note_crypto_pk_op(SIGN_DIR);
if (router_append_dirobj_signature(status, status_len,digest,DIGEST_LEN,
private_key)<0) {
{
char *sig;
if (!(sig = router_get_dirobj_signature(digest,DIGEST_LEN,
private_key))) {
log_warn(LD_BUG, "Unable to sign router status.");
goto done;
}
smartlist_add(chunks, sig);
}
status = smartlist_join_strings(chunks, "", 0, NULL);
{
networkstatus_v2_t *ns;

64
src/or/dirvote.c
View File

@ -75,7 +75,6 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
char *client_versions_line = NULL, *server_versions_line = NULL;
networkstatus_voter_info_t *voter;
char *status = NULL;
size_t status_len;
tor_assert(private_signing_key);
tor_assert(v3_ns->type == NS_TYPE_VOTE || v3_ns->type == NS_TYPE_OPINION);
@ -185,6 +184,11 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
smartlist_add(chunks, tor_strdup("directory-footer\n"));
/* The digest includes everything up through the space after
* directory-signature. (Yuck.) */
crypto_digest_smartlist(digest, DIGEST_LEN, chunks,
"directory-signature ", DIGEST_SHA1);
{
char signing_key_fingerprint[FINGERPRINT_LEN+1];
if (crypto_pk_get_fingerprint(private_signing_key,
@ -197,21 +201,18 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
signing_key_fingerprint);
}
status = smartlist_join_strings(chunks, "", 0, NULL);
#define MAX_VOTE_SIGNATURE_LEN 4096
status_len = strlen(status) + MAX_VOTE_SIGNATURE_LEN + 1;
status = tor_realloc(status, status_len);
if (router_get_networkstatus_v3_hash(status, digest, DIGEST_SHA1)<0)
goto err;
note_crypto_pk_op(SIGN_DIR);
if (router_append_dirobj_signature(status+strlen(status),
status_len,
digest, DIGEST_LEN,
private_signing_key)<0) {
{
char *sig = router_get_dirobj_signature(digest, DIGEST_LEN,
private_signing_key);
if (!sig) {
log_warn(LD_BUG, "Unable to sign networkstatus vote.");
goto err;
}
smartlist_add(chunks, sig);
}
status = smartlist_join_strings(chunks, "", 0, NULL);
{
networkstatus_t *v;
@ -479,24 +480,6 @@ compute_routerstatus_consensus(smartlist_t *votes, int consensus_method,
return most;
}
/** Given a list of strings in <b>lst</b>, set the <b>len_out</b>-byte digest
* at <b>digest_out</b> to the hash of the concatenation of those strings,
* computed with the algorithm <b>alg</b>. */
static void
hash_list_members(char *digest_out, size_t len_out,
smartlist_t *lst, digest_algorithm_t alg)
{
crypto_digest_t *d;
if (alg == DIGEST_SHA1)
d = crypto_digest_new();
else
d = crypto_digest256_new(alg);
SMARTLIST_FOREACH(lst, const char *, cp,
crypto_digest_add_bytes(d, cp, strlen(cp)));
crypto_digest_get_digest(d, digest_out, len_out);
crypto_digest_free(d);
}
/** Sorting helper: compare two strings based on their values as base-ten
* positive integers. (Non-integers are treated as prior to all integers, and
* compared lexically.) */
@ -2095,12 +2078,12 @@ networkstatus_compute_consensus(smartlist_t *votes,
size_t digest_len =
flavor == FLAV_NS ? DIGEST_LEN : DIGEST256_LEN;
const char *algname = crypto_digest_algorithm_get_name(digest_alg);
char sigbuf[4096];
char *signature;
smartlist_add(chunks, tor_strdup("directory-signature "));
/* Compute the hash of the chunks. */
hash_list_members(digest, digest_len, chunks, digest_alg);
crypto_digest_smartlist(digest, digest_len, chunks, "", digest_alg);
/* Get the fingerprints */
crypto_pk_get_fingerprint(identity_key, fingerprint, 0);
@ -2116,14 +2099,12 @@ networkstatus_compute_consensus(smartlist_t *votes,
signing_key_fingerprint);
}
/* And the signature. */
sigbuf[0] = '\0';
if (router_append_dirobj_signature(sigbuf, sizeof(sigbuf),
digest, digest_len,
signing_key)) {
if (!(signature = router_get_dirobj_signature(digest, digest_len,
signing_key))) {
log_warn(LD_BUG, "Couldn't sign consensus networkstatus.");
goto done;
}
smartlist_add(chunks, tor_strdup(sigbuf));
smartlist_add(chunks, signature);
if (legacy_id_key_digest && legacy_signing_key && consensus_method >= 3) {
smartlist_add(chunks, tor_strdup("directory-signature "));
@ -2139,14 +2120,13 @@ networkstatus_compute_consensus(smartlist_t *votes,
algname, fingerprint,
signing_key_fingerprint);
}
sigbuf[0] = '\0';
if (router_append_dirobj_signature(sigbuf, sizeof(sigbuf),
digest, digest_len,
legacy_signing_key)) {
if (!(signature = router_get_dirobj_signature(digest, digest_len,
legacy_signing_key))) {
log_warn(LD_BUG, "Couldn't sign consensus networkstatus.");
goto done;
}
smartlist_add(chunks, tor_strdup(sigbuf));
smartlist_add(chunks, signature);
}
}

21
src/or/router.c
View File

@ -2248,7 +2248,6 @@ router_dump_router_to_string(routerinfo_t *router,
const or_options_t *options = get_options();
smartlist_t *chunks = NULL;
char *output = NULL;
size_t output_len;
/* Make sure the identity key matches the one in the routerinfo. */
if (!crypto_pk_eq_keys(ident_key, router->identity_pkey)) {
@ -2395,24 +2394,22 @@ router_dump_router_to_string(routerinfo_t *router,
/* Sign the descriptor */
smartlist_add(chunks, tor_strdup("router-signature\n"));
output = smartlist_join_strings(chunks, "", 0, NULL);
#define MAX_DESC_SIGNATURE_LEN 4096
output_len = strlen(output) + MAX_DESC_SIGNATURE_LEN + 1;
output = tor_realloc(output, output_len);
if (router_get_router_hash(output, strlen(output), digest) < 0) {
goto err;
}
crypto_digest_smartlist(digest, DIGEST_LEN, chunks, "", DIGEST_SHA1);
note_crypto_pk_op(SIGN_RTR);
if (router_append_dirobj_signature(output, output_len,
digest,DIGEST_LEN,ident_key)<0) {
{
char *sig;
if (!(sig = router_get_dirobj_signature(digest, DIGEST_LEN, ident_key))) {
log_warn(LD_BUG, "Couldn't sign router descriptor");
goto err;
}
smartlist_add(chunks, sig);
}
/* include a last '\n' */
strlcat(output, "\n", output_len);
smartlist_add(chunks, tor_strdup("\n"));
output = smartlist_join_strings(chunks, "", 0, NULL);
#ifdef DEBUG_ROUTER_DUMP_ROUTER_TO_STRING
{

57
src/or/routerparse.c
View File

@ -683,20 +683,19 @@ router_get_extrainfo_hash(const char *s, size_t s_len, char *digest)
"\nrouter-signature",'\n', DIGEST_SHA1);
}
/** Helper: used to generate signatures for routers, directories and
* network-status objects. Given a digest in <b>digest</b> and a secret
* <b>private_key</b>, generate an PKCS1-padded signature, BASE64-encode it,
* surround it with -----BEGIN/END----- pairs, and write it to the
* <b>buf_len</b>-byte buffer at <b>buf</b>. Return 0 on success, -1 on
* failure.
*/
int
router_append_dirobj_signature(char *buf, size_t buf_len, const char *digest,
size_t digest_len, crypto_pk_t *private_key)
/** DOCDOC */
char *
router_get_dirobj_signature(const char *digest,
size_t digest_len,
crypto_pk_t *private_key)
{
char *signature;
size_t i, keysize;
int siglen;
char *buf = NULL;
size_t buf_len;
/* overestimate of BEGIN/END lines total len. */
#define BEGIN_END_OVERHEAD_LEN 64
keysize = crypto_pk_keysize(private_key);
signature = tor_malloc(keysize);
@ -706,7 +705,12 @@ router_append_dirobj_signature(char *buf, size_t buf_len, const char *digest,
log_warn(LD_BUG,"Couldn't sign digest.");
goto err;
}
if (strlcat(buf, "-----BEGIN SIGNATURE-----\n", buf_len) >= buf_len)
/* The *2 here is a ridiculous overestimate of base-64 overhead. */
buf_len = (siglen * 2) + BEGIN_END_OVERHEAD_LEN;
buf = tor_malloc(buf_len);
if (strlcpy(buf, "-----BEGIN SIGNATURE-----\n", buf_len) >= buf_len)
goto truncated;
i = strlen(buf);
@ -719,13 +723,42 @@ router_append_dirobj_signature(char *buf, size_t buf_len, const char *digest,
goto truncated;
tor_free(signature);
return 0;
return buf;
truncated:
log_warn(LD_BUG,"tried to exceed string length.");
err:
tor_free(signature);
tor_free(buf);
return NULL;
}
/** Helper: used to generate signatures for routers, directories and
* network-status objects. Given a digest in <b>digest</b> and a secret
* <b>private_key</b>, generate an PKCS1-padded signature, BASE64-encode it,
* surround it with -----BEGIN/END----- pairs, and write it to the
* <b>buf_len</b>-byte buffer at <b>buf</b>. Return 0 on success, -1 on
* failure.
*/
int
router_append_dirobj_signature(char *buf, size_t buf_len, const char *digest,
size_t digest_len, crypto_pk_t *private_key)
{
size_t sig_len, s_len;
char *sig = router_get_dirobj_signature(digest, digest_len, private_key);
if (!sig) {
log_warn(LD_BUG, "No signature generated");
return -1;
}
sig_len = strlen(sig);
s_len = strlen(buf);
if (sig_len + s_len + 1 > buf_len) {
log_warn(LD_BUG, "Not enough room for signature");
tor_free(sig);
return -1;
}
memcpy(buf+s_len, sig, sig_len+1);
return 0;
}
/** Return VS_RECOMMENDED if <b>myversion</b> is contained in

3
src/or/routerparse.h
View File

@ -21,6 +21,9 @@ int router_get_networkstatus_v3_hash(const char *s, char *digest,
int router_get_networkstatus_v3_hashes(const char *s, digests_t *digests);
int router_get_extrainfo_hash(const char *s, size_t s_len, char *digest);
#define DIROBJ_MAX_SIG_LEN 256
char *router_get_dirobj_signature(const char *digest,
size_t digest_len,
crypto_pk_t *private_key);
int router_append_dirobj_signature(char *buf, size_t buf_len,
const char *digest,
size_t digest_len,