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https://gitlab.torproject.org/tpo/core/tor.git
synced 2024-11-24 04:13:28 +01:00
Reload unparseable descriptor dump FIFO state from on-disk dumped descriptors at startup
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38cced90ef
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421cf21b3c
@ -588,6 +588,8 @@ static int check_signature_token(const char *digest,
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/* Dump mechanism for unparseable descriptors */
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static void dump_desc_populate_fifo_from_directory(const char *dirname);
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/** List of dumped descriptors for FIFO cleanup purposes */
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STATIC smartlist_t *descs_dumped = NULL;
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/** Total size of dumped descriptors for FIFO cleanup */
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@ -597,6 +599,7 @@ static int have_dump_desc_dir = 0;
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static int problem_with_dump_desc_dir = 0;
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#define DESC_DUMP_DATADIR_SUBDIR "unparseable-descs"
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#define DESC_DUMP_BASE_FILENAME "unparseable-desc"
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/*
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* One entry in the list of dumped descriptors; filename dumped to, length
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@ -607,6 +610,7 @@ typedef struct {
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char *filename;
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size_t len;
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uint8_t digest_sha256[DIGEST256_LEN];
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time_t when;
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} dumped_desc_t;
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/** Find the dump directory and check if we'll be able to create it */
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@ -660,6 +664,10 @@ dump_desc_init(void)
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problem_with_dump_desc_dir = 1;
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}
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if (have_dump_desc_dir && !problem_with_dump_desc_dir) {
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dump_desc_populate_fifo_from_directory(dump_desc_dir);
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}
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tor_free(dump_desc_dir);
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}
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@ -718,6 +726,7 @@ dump_desc_fifo_add_and_clean(char *filename, const uint8_t *digest_sha256,
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ent = tor_malloc_zero(sizeof(*ent));
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ent->filename = filename;
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ent->len = len;
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ent->when = time(NULL);
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memcpy(ent->digest_sha256, digest_sha256, DIGEST256_LEN);
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/* Do we need to do some cleanup? */
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@ -790,6 +799,8 @@ dump_desc_fifo_bump_hash(const uint8_t *digest_sha256)
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} SMARTLIST_FOREACH_END(ent);
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if (match) {
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/* Update the timestamp */
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match->when = time(NULL);
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/* Add it back at the end of the list */
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smartlist_add(descs_dumped, match);
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@ -820,6 +831,225 @@ dump_desc_fifo_cleanup(void)
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}
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}
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/** Handle one file for dump_desc_populate_fifo_from_directory(); make sure
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* the filename is sensibly formed and matches the file content, and either
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* return a dumped_desc_t for it or remove the file and return NULL.
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*/
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static dumped_desc_t *
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dump_desc_populate_one_file(const char *dirname, const char *f)
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{
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dumped_desc_t *ent = NULL;
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char *path = NULL, *desc = NULL;
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const char *digest_str;
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char digest[DIGEST256_LEN], content_digest[DIGEST256_LEN];
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/* Expected prefix before digest in filenames */
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const char *f_pfx = DESC_DUMP_BASE_FILENAME ".";
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/*
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* Stat while reading; this is important in case the file
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* contains a NUL character.
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*/
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struct stat st;
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/* Sanity-check args */
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tor_assert(dirname != NULL);
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tor_assert(f != NULL);
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/* Form the full path */
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tor_asprintf(&path, "%s" PATH_SEPARATOR "%s", dirname, f);
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/* Check that f has the form DESC_DUMP_BASE_FILENAME.<digest256> */
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if (!strcmpstart(f, f_pfx)) {
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/* It matches the form, but is the digest parseable as such? */
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digest_str = f + strlen(f_pfx);
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if (base16_decode(digest, DIGEST256_LEN,
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digest_str, strlen(digest_str)) != DIGEST256_LEN) {
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/* We failed to decode it */
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digest_str = NULL;
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}
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} else {
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/* No match */
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digest_str = NULL;
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}
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if (!digest_str) {
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/* We couldn't get a sensible digest */
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log_notice(LD_DIR,
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"Removing unrecognized filename %s from unparseable "
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"descriptors directory", f);
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tor_unlink(path);
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/* We're done */
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goto done;
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}
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/*
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* The filename has the form DESC_DUMP_BASE_FILENAME "." <digest256> and
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* we've decoded the digest. Next, check that we can read it and the
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* content matches this digest. We are relying on the fact that if the
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* file contains a '\0', read_file_to_str() will allocate space for and
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* read the entire file and return the correct size in st.
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*/
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desc = read_file_to_str(path, RFTS_IGNORE_MISSING, &st);
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if (!desc) {
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/* We couldn't read it */
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log_notice(LD_DIR,
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"Failed to read %s from unparseable descriptors directory; "
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"attempting to remove it.", f);
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tor_unlink(path);
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/* We're done */
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goto done;
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}
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/*
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* We got one; now compute its digest and check that it matches the
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* filename.
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*/
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if (crypto_digest256((char *)content_digest, desc, st.st_size,
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DIGEST_SHA256) != 0) {
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/* Weird, but okay */
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log_info(LD_DIR,
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"Unable to hash content of %s from unparseable descriptors "
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"directory", f);
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tor_unlink(path);
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/* We're done */
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goto done;
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}
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/* Compare the digests */
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if (memcmp(digest, content_digest, DIGEST256_LEN) != 0) {
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/* No match */
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log_info(LD_DIR,
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"Hash of %s from unparseable descriptors directory didn't "
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"match its filename; removing it", f);
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tor_unlink(path);
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/* We're done */
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goto done;
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}
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/* Okay, it's a match, we should prepare ent */
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ent = tor_malloc_zero(sizeof(dumped_desc_t));
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ent->filename = path;
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memcpy(ent->digest_sha256, digest, DIGEST256_LEN);
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ent->len = st.st_size;
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ent->when = st.st_mtime;
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/* Null out path so we don't free it out from under ent */
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path = NULL;
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done:
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/* Free allocations if we had them */
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tor_free(desc);
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tor_free(path);
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return ent;
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}
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/** Sort helper for dump_desc_populate_fifo_from_directory(); compares
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* the when field of dumped_desc_ts in a smartlist to put the FIFO in
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* the correct order after reconstructing it from the directory.
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*/
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static int
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dump_desc_compare_fifo_entries(const void **a_v, const void **b_v)
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{
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const dumped_desc_t **a = (const dumped_desc_t **)a_v;
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const dumped_desc_t **b = (const dumped_desc_t **)b_v;
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if ((a != NULL) && (*a != NULL)) {
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if ((b != NULL) && (*b != NULL)) {
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/* We have sensible dumped_desc_ts to compare */
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if ((*a)->when < (*b)->when) {
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return -1;
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} else if ((*a)->when == (*b)->when) {
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return 0;
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} else {
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return 1;
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}
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} else {
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/*
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* We shouldn't see this, but what the hell, NULLs precede everythin
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* else
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*/
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return 1;
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}
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} else {
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return -1;
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}
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}
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/** Scan the contents of the directory, and update FIFO/counters; this will
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* consistency-check descriptor dump filenames against hashes of descriptor
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* dump file content, and remove any inconsistent/unreadable dumps, and then
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* reconstruct the dump FIFO as closely as possible for the last time the
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* tor process shut down. If a previous dump was repeated more than once and
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* moved ahead in the FIFO, the mtime will not have been updated and the
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* reconstructed order will be wrong, but will always be a permutation of
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* the original.
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*/
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static void
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dump_desc_populate_fifo_from_directory(const char *dirname)
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{
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smartlist_t *files = NULL;
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dumped_desc_t *ent = NULL;
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tor_assert(dirname != NULL);
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/* Get a list of files */
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files = tor_listdir(dirname);
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if (!files) {
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log_notice(LD_DIR,
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"Unable to get contents of unparseable descriptor dump "
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"directory %s",
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dirname);
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return;
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}
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/*
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* Iterate through the list and decide which files should go in the
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* FIFO and which should be purged.
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*/
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SMARTLIST_FOREACH_BEGIN(files, char *, f) {
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/* Try to get a FIFO entry */
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ent = dump_desc_populate_one_file(dirname, f);
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if (ent) {
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/*
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* We got one; add it to the FIFO. No need for duplicate checking
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* here since we just verified the name and digest match.
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*/
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/* Make sure we have a list to add it to */
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if (!descs_dumped) {
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descs_dumped = smartlist_new();
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len_descs_dumped = 0;
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}
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/* Add it and adjust the counter */
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smartlist_add(descs_dumped, ent);
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len_descs_dumped += ent->len;
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}
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/*
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* If we didn't, we will have unlinked the file if necessary and
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* possible, and emitted a log message about it, so just go on to
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* the next.
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*/
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} SMARTLIST_FOREACH_END(f);
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/* Did we get anything? */
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if (descs_dumped != NULL) {
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/* Sort the FIFO in order of increasing timestamp */
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smartlist_sort(descs_dumped, dump_desc_compare_fifo_entries);
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/* Log some stats */
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log_info(LD_DIR,
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"Reloaded unparseable descriptor dump FIFO with %d dump(s) "
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"totaling " U64_FORMAT " bytes",
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smartlist_len(descs_dumped), U64_PRINTF_ARG(len_descs_dumped));
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}
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/* Free the original list */
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SMARTLIST_FOREACH(files, char *, f, tor_free(f));
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smartlist_free(files);
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}
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/** For debugging purposes, dump unparseable descriptor *<b>desc</b> of
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* type *<b>type</b> to file $DATADIR/unparseable-desc. Do not write more
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* than one descriptor to disk per minute. If there is already such a
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@ -853,7 +1083,8 @@ dump_desc(const char *desc, const char *type)
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* We mention type and hash in the main log; don't clutter up the files
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* with anything but the exact dump.
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*/
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tor_asprintf(&debugfile_base, "unparseable-desc.%s", digest_sha256_hex);
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tor_asprintf(&debugfile_base,
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DESC_DUMP_BASE_FILENAME ".%s", digest_sha256_hex);
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debugfile = get_datadir_fname2(DESC_DUMP_DATADIR_SUBDIR, debugfile_base);
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if (!sandbox_is_active()) {
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