consdiffmgr: function to re-validate stored sha3 digests at startup

This commit is contained in:
Nick Mathewson 2017-04-15 11:43:53 -04:00
parent 6c86e63029
commit 655f1c8e01
3 changed files with 59 additions and 2 deletions

View File

@ -370,8 +370,6 @@ consdiffmgr_cleanup(void)
smartlist_free(objects);
smartlist_free(consensuses);
smartlist_free(diffs);
// XXXX for anything where the sha3 doesn't match -- delete it. But not
// XXXX here. Somewhere else?
// Actually remove files, if they're not used.
consensus_cache_delete_pending(cdm_cache_get());
@ -390,6 +388,61 @@ consdiffmgr_configure(const consdiff_cfg_t *cfg)
(void) cdm_cache_get();
}
/**
* Scan the consensus diff manager's cache for any grossly malformed entries,
* and mark them as deletable. Return 0 if no problems were found; 1
* if problems were found and fixed.
*/
int
consdiffmgr_validate(void)
{
/* Right now, we only check for entries that have bad sha3 values */
int problems = 0;
smartlist_t *objects = smartlist_new();
consensus_cache_find_all(objects, cdm_cache_get(),
NULL, NULL);
SMARTLIST_FOREACH_BEGIN(objects, consensus_cache_entry_t *, obj) {
const char *lv_sha3 =
consensus_cache_entry_get_value(obj, LABEL_SHA3_DIGEST);
if (lv_sha3 == NULL)
continue;
uint8_t sha3_expected[DIGEST256_LEN];
uint8_t sha3_received[DIGEST256_LEN];
int r = cdm_entry_get_sha3_value(sha3_expected, obj, LABEL_SHA3_DIGEST);
if (r == -1) {
/* digest isn't there; that's allowed */
continue;
} else if (r == -2) {
/* digest is malformed; that's not allowed */
problems = 1;
consensus_cache_entry_mark_for_removal(obj);
continue;
}
const uint8_t *body;
size_t bodylen;
consensus_cache_entry_incref(obj);
r = consensus_cache_entry_get_body(obj, &body, &bodylen);
if (r == 0) {
crypto_digest256((char *)sha3_received, (const char *)body, bodylen,
DIGEST_SHA3_256);
}
consensus_cache_entry_decref(obj);
if (r < 0)
continue;
if (fast_memneq(sha3_received, sha3_expected, DIGEST256_LEN)) {
problems = 1;
consensus_cache_entry_mark_for_removal(obj);
continue;
}
} SMARTLIST_FOREACH_END(obj);
smartlist_free(objects);
return problems;
}
/**
* Helper: build new diffs of <b>flavor</b> as needed
*/

View File

@ -33,6 +33,7 @@ void consdiffmgr_rescan(void);
int consdiffmgr_cleanup(void);
void consdiffmgr_configure(const consdiff_cfg_t *cfg);
void consdiffmgr_free_all(void);
int consdiffmgr_validate(void);
#ifdef CONSDIFFMGR_PRIVATE
STATIC consensus_cache_t *cdm_cache_get(void);

View File

@ -556,6 +556,9 @@ test_consdiffmgr_cleanup_old_diffs(void *arg)
tt_int_op(0, OP_EQ, consdiffmgr_add_consensus(md_body[3], md_ns[3]));
tt_int_op(2, OP_EQ, consdiffmgr_cleanup());
/* Everything should be valid at this point */
tt_int_op(0, OP_EQ, consdiffmgr_validate());
done:
for (i = 0; i < N; ++i) {
tor_free(md_body[i]);