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-rw-r--r--src/feature/dirparse/unparseable.c591
1 files changed, 591 insertions, 0 deletions
diff --git a/src/feature/dirparse/unparseable.c b/src/feature/dirparse/unparseable.c
new file mode 100644
index 0000000000..941b5a1f6d
--- /dev/null
+++ b/src/feature/dirparse/unparseable.c
@@ -0,0 +1,591 @@
+/* Copyright (c) 2001 Matej Pfajfar.
+ * Copyright (c) 2001-2004, Roger Dingledine.
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2019, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+#define UNPARSEABLE_PRIVATE
+
+#include "core/or/or.h"
+#include "app/config/config.h"
+#include "feature/dirparse/unparseable.h"
+#include "lib/sandbox/sandbox.h"
+
+#ifdef HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+
+/* Dump mechanism for unparseable descriptors */
+
+/** List of dumped descriptors for FIFO cleanup purposes */
+STATIC smartlist_t *descs_dumped = NULL;
+/** Total size of dumped descriptors for FIFO cleanup */
+STATIC uint64_t len_descs_dumped = 0;
+/** Directory to stash dumps in */
+static int have_dump_desc_dir = 0;
+static int problem_with_dump_desc_dir = 0;
+
+#define DESC_DUMP_DATADIR_SUBDIR "unparseable-descs"
+#define DESC_DUMP_BASE_FILENAME "unparseable-desc"
+
+/** Find the dump directory and check if we'll be able to create it */
+void
+dump_desc_init(void)
+{
+ char *dump_desc_dir;
+
+ dump_desc_dir = get_datadir_fname(DESC_DUMP_DATADIR_SUBDIR);
+
+ /*
+ * We just check for it, don't create it at this point; we'll
+ * create it when we need it if it isn't already there.
+ */
+ if (check_private_dir(dump_desc_dir, CPD_CHECK, get_options()->User) < 0) {
+ /* Error, log and flag it as having a problem */
+ log_notice(LD_DIR,
+ "Doesn't look like we'll be able to create descriptor dump "
+ "directory %s; dumps will be disabled.",
+ dump_desc_dir);
+ problem_with_dump_desc_dir = 1;
+ tor_free(dump_desc_dir);
+ return;
+ }
+
+ /* Check if it exists */
+ switch (file_status(dump_desc_dir)) {
+ case FN_DIR:
+ /* We already have a directory */
+ have_dump_desc_dir = 1;
+ break;
+ case FN_NOENT:
+ /* Nothing, we'll need to create it later */
+ have_dump_desc_dir = 0;
+ break;
+ case FN_ERROR:
+ /* Log and flag having a problem */
+ log_notice(LD_DIR,
+ "Couldn't check whether descriptor dump directory %s already"
+ " exists: %s",
+ dump_desc_dir, strerror(errno));
+ problem_with_dump_desc_dir = 1;
+ break;
+ case FN_FILE:
+ case FN_EMPTY:
+ default:
+ /* Something else was here! */
+ log_notice(LD_DIR,
+ "Descriptor dump directory %s already exists and isn't a "
+ "directory",
+ dump_desc_dir);
+ problem_with_dump_desc_dir = 1;
+ }
+
+ if (have_dump_desc_dir && !problem_with_dump_desc_dir) {
+ dump_desc_populate_fifo_from_directory(dump_desc_dir);
+ }
+
+ tor_free(dump_desc_dir);
+}
+
+/** Create the dump directory if needed and possible */
+static void
+dump_desc_create_dir(void)
+{
+ char *dump_desc_dir;
+
+ /* If the problem flag is set, skip it */
+ if (problem_with_dump_desc_dir) return;
+
+ /* Do we need it? */
+ if (!have_dump_desc_dir) {
+ dump_desc_dir = get_datadir_fname(DESC_DUMP_DATADIR_SUBDIR);
+
+ if (check_private_dir(dump_desc_dir, CPD_CREATE,
+ get_options()->User) < 0) {
+ log_notice(LD_DIR,
+ "Failed to create descriptor dump directory %s",
+ dump_desc_dir);
+ problem_with_dump_desc_dir = 1;
+ }
+
+ /* Okay, we created it */
+ have_dump_desc_dir = 1;
+
+ tor_free(dump_desc_dir);
+ }
+}
+
+/** Dump desc FIFO/cleanup; take ownership of the given filename, add it to
+ * the FIFO, and clean up the oldest entries to the extent they exceed the
+ * configured cap. If any old entries with a matching hash existed, they
+ * just got overwritten right before this was called and we should adjust
+ * the total size counter without deleting them.
+ */
+static void
+dump_desc_fifo_add_and_clean(char *filename, const uint8_t *digest_sha256,
+ size_t len)
+{
+ dumped_desc_t *ent = NULL, *tmp;
+ uint64_t max_len;
+
+ tor_assert(filename != NULL);
+ tor_assert(digest_sha256 != NULL);
+
+ if (descs_dumped == NULL) {
+ /* We better have no length, then */
+ tor_assert(len_descs_dumped == 0);
+ /* Make a smartlist */
+ descs_dumped = smartlist_new();
+ }
+
+ /* Make a new entry to put this one in */
+ ent = tor_malloc_zero(sizeof(*ent));
+ ent->filename = filename;
+ ent->len = len;
+ ent->when = time(NULL);
+ memcpy(ent->digest_sha256, digest_sha256, DIGEST256_LEN);
+
+ /* Do we need to do some cleanup? */
+ max_len = get_options()->MaxUnparseableDescSizeToLog;
+ /* Iterate over the list until we've freed enough space */
+ while (len > max_len - len_descs_dumped &&
+ smartlist_len(descs_dumped) > 0) {
+ /* Get the oldest thing on the list */
+ tmp = (dumped_desc_t *)(smartlist_get(descs_dumped, 0));
+
+ /*
+ * Check if it matches the filename we just added, so we don't delete
+ * something we just emitted if we get repeated identical descriptors.
+ */
+ if (strcmp(tmp->filename, filename) != 0) {
+ /* Delete it and adjust the length counter */
+ tor_unlink(tmp->filename);
+ tor_assert(len_descs_dumped >= tmp->len);
+ len_descs_dumped -= tmp->len;
+ log_info(LD_DIR,
+ "Deleting old unparseable descriptor dump %s due to "
+ "space limits",
+ tmp->filename);
+ } else {
+ /*
+ * Don't delete, but do adjust the counter since we will bump it
+ * later
+ */
+ tor_assert(len_descs_dumped >= tmp->len);
+ len_descs_dumped -= tmp->len;
+ log_info(LD_DIR,
+ "Replacing old descriptor dump %s with new identical one",
+ tmp->filename);
+ }
+
+ /* Free it and remove it from the list */
+ smartlist_del_keeporder(descs_dumped, 0);
+ tor_free(tmp->filename);
+ tor_free(tmp);
+ }
+
+ /* Append our entry to the end of the list and bump the counter */
+ smartlist_add(descs_dumped, ent);
+ len_descs_dumped += len;
+}
+
+/** Check if we already have a descriptor for this hash and move it to the
+ * head of the queue if so. Return 1 if one existed and 0 otherwise.
+ */
+static int
+dump_desc_fifo_bump_hash(const uint8_t *digest_sha256)
+{
+ dumped_desc_t *match = NULL;
+
+ tor_assert(digest_sha256);
+
+ if (descs_dumped) {
+ /* Find a match if one exists */
+ SMARTLIST_FOREACH_BEGIN(descs_dumped, dumped_desc_t *, ent) {
+ if (ent &&
+ tor_memeq(ent->digest_sha256, digest_sha256, DIGEST256_LEN)) {
+ /*
+ * Save a pointer to the match and remove it from its current
+ * position.
+ */
+ match = ent;
+ SMARTLIST_DEL_CURRENT_KEEPORDER(descs_dumped, ent);
+ break;
+ }
+ } SMARTLIST_FOREACH_END(ent);
+
+ if (match) {
+ /* Update the timestamp */
+ match->when = time(NULL);
+ /* Add it back at the end of the list */
+ smartlist_add(descs_dumped, match);
+
+ /* Indicate we found one */
+ return 1;
+ }
+ }
+
+ return 0;
+}
+
+/** Clean up on exit; just memory, leave the dumps behind
+ */
+void
+dump_desc_fifo_cleanup(void)
+{
+ if (descs_dumped) {
+ /* Free each descriptor */
+ SMARTLIST_FOREACH_BEGIN(descs_dumped, dumped_desc_t *, ent) {
+ tor_assert(ent);
+ tor_free(ent->filename);
+ tor_free(ent);
+ } SMARTLIST_FOREACH_END(ent);
+ /* Free the list */
+ smartlist_free(descs_dumped);
+ descs_dumped = NULL;
+ len_descs_dumped = 0;
+ }
+}
+
+/** Handle one file for dump_desc_populate_fifo_from_directory(); make sure
+ * the filename is sensibly formed and matches the file content, and either
+ * return a dumped_desc_t for it or remove the file and return NULL.
+ */
+MOCK_IMPL(STATIC dumped_desc_t *,
+dump_desc_populate_one_file, (const char *dirname, const char *f))
+{
+ dumped_desc_t *ent = NULL;
+ char *path = NULL, *desc = NULL;
+ const char *digest_str;
+ char digest[DIGEST256_LEN], content_digest[DIGEST256_LEN];
+ /* Expected prefix before digest in filenames */
+ const char *f_pfx = DESC_DUMP_BASE_FILENAME ".";
+ /*
+ * Stat while reading; this is important in case the file
+ * contains a NUL character.
+ */
+ struct stat st;
+
+ /* Sanity-check args */
+ tor_assert(dirname != NULL);
+ tor_assert(f != NULL);
+
+ /* Form the full path */
+ tor_asprintf(&path, "%s" PATH_SEPARATOR "%s", dirname, f);
+
+ /* Check that f has the form DESC_DUMP_BASE_FILENAME.<digest256> */
+
+ if (!strcmpstart(f, f_pfx)) {
+ /* It matches the form, but is the digest parseable as such? */
+ digest_str = f + strlen(f_pfx);
+ if (base16_decode(digest, DIGEST256_LEN,
+ digest_str, strlen(digest_str)) != DIGEST256_LEN) {
+ /* We failed to decode it */
+ digest_str = NULL;
+ }
+ } else {
+ /* No match */
+ digest_str = NULL;
+ }
+
+ if (!digest_str) {
+ /* We couldn't get a sensible digest */
+ log_notice(LD_DIR,
+ "Removing unrecognized filename %s from unparseable "
+ "descriptors directory", f);
+ tor_unlink(path);
+ /* We're done */
+ goto done;
+ }
+
+ /*
+ * The filename has the form DESC_DUMP_BASE_FILENAME "." <digest256> and
+ * we've decoded the digest. Next, check that we can read it and the
+ * content matches this digest. We are relying on the fact that if the
+ * file contains a '\0', read_file_to_str() will allocate space for and
+ * read the entire file and return the correct size in st.
+ */
+ desc = read_file_to_str(path, RFTS_IGNORE_MISSING|RFTS_BIN, &st);
+ if (!desc) {
+ /* We couldn't read it */
+ log_notice(LD_DIR,
+ "Failed to read %s from unparseable descriptors directory; "
+ "attempting to remove it.", f);
+ tor_unlink(path);
+ /* We're done */
+ goto done;
+ }
+
+#if SIZE_MAX > UINT64_MAX
+ if (BUG((uint64_t)st.st_size > (uint64_t)SIZE_MAX)) {
+ /* LCOV_EXCL_START
+ * Should be impossible since RFTS above should have failed to read the
+ * huge file into RAM. */
+ goto done;
+ /* LCOV_EXCL_STOP */
+ }
+#endif /* SIZE_MAX > UINT64_MAX */
+ if (BUG(st.st_size < 0)) {
+ /* LCOV_EXCL_START
+ * Should be impossible, since the OS isn't supposed to be b0rken. */
+ goto done;
+ /* LCOV_EXCL_STOP */
+ }
+ /* (Now we can be sure that st.st_size is safe to cast to a size_t.) */
+
+ /*
+ * We got one; now compute its digest and check that it matches the
+ * filename.
+ */
+ if (crypto_digest256((char *)content_digest, desc, (size_t) st.st_size,
+ DIGEST_SHA256) < 0) {
+ /* Weird, but okay */
+ log_info(LD_DIR,
+ "Unable to hash content of %s from unparseable descriptors "
+ "directory", f);
+ tor_unlink(path);
+ /* We're done */
+ goto done;
+ }
+
+ /* Compare the digests */
+ if (tor_memneq(digest, content_digest, DIGEST256_LEN)) {
+ /* No match */
+ log_info(LD_DIR,
+ "Hash of %s from unparseable descriptors directory didn't "
+ "match its filename; removing it", f);
+ tor_unlink(path);
+ /* We're done */
+ goto done;
+ }
+
+ /* Okay, it's a match, we should prepare ent */
+ ent = tor_malloc_zero(sizeof(dumped_desc_t));
+ ent->filename = path;
+ memcpy(ent->digest_sha256, digest, DIGEST256_LEN);
+ ent->len = (size_t) st.st_size;
+ ent->when = st.st_mtime;
+ /* Null out path so we don't free it out from under ent */
+ path = NULL;
+
+ done:
+ /* Free allocations if we had them */
+ tor_free(desc);
+ tor_free(path);
+
+ return ent;
+}
+
+/** Sort helper for dump_desc_populate_fifo_from_directory(); compares
+ * the when field of dumped_desc_ts in a smartlist to put the FIFO in
+ * the correct order after reconstructing it from the directory.
+ */
+static int
+dump_desc_compare_fifo_entries(const void **a_v, const void **b_v)
+{
+ const dumped_desc_t **a = (const dumped_desc_t **)a_v;
+ const dumped_desc_t **b = (const dumped_desc_t **)b_v;
+
+ if ((a != NULL) && (*a != NULL)) {
+ if ((b != NULL) && (*b != NULL)) {
+ /* We have sensible dumped_desc_ts to compare */
+ if ((*a)->when < (*b)->when) {
+ return -1;
+ } else if ((*a)->when == (*b)->when) {
+ return 0;
+ } else {
+ return 1;
+ }
+ } else {
+ /*
+ * We shouldn't see this, but what the hell, NULLs precede everythin
+ * else
+ */
+ return 1;
+ }
+ } else {
+ return -1;
+ }
+}
+
+/** Scan the contents of the directory, and update FIFO/counters; this will
+ * consistency-check descriptor dump filenames against hashes of descriptor
+ * dump file content, and remove any inconsistent/unreadable dumps, and then
+ * reconstruct the dump FIFO as closely as possible for the last time the
+ * tor process shut down. If a previous dump was repeated more than once and
+ * moved ahead in the FIFO, the mtime will not have been updated and the
+ * reconstructed order will be wrong, but will always be a permutation of
+ * the original.
+ */
+STATIC void
+dump_desc_populate_fifo_from_directory(const char *dirname)
+{
+ smartlist_t *files = NULL;
+ dumped_desc_t *ent = NULL;
+
+ tor_assert(dirname != NULL);
+
+ /* Get a list of files */
+ files = tor_listdir(dirname);
+ if (!files) {
+ log_notice(LD_DIR,
+ "Unable to get contents of unparseable descriptor dump "
+ "directory %s",
+ dirname);
+ return;
+ }
+
+ /*
+ * Iterate through the list and decide which files should go in the
+ * FIFO and which should be purged.
+ */
+
+ SMARTLIST_FOREACH_BEGIN(files, char *, f) {
+ /* Try to get a FIFO entry */
+ ent = dump_desc_populate_one_file(dirname, f);
+ if (ent) {
+ /*
+ * We got one; add it to the FIFO. No need for duplicate checking
+ * here since we just verified the name and digest match.
+ */
+
+ /* Make sure we have a list to add it to */
+ if (!descs_dumped) {
+ descs_dumped = smartlist_new();
+ len_descs_dumped = 0;
+ }
+
+ /* Add it and adjust the counter */
+ smartlist_add(descs_dumped, ent);
+ len_descs_dumped += ent->len;
+ }
+ /*
+ * If we didn't, we will have unlinked the file if necessary and
+ * possible, and emitted a log message about it, so just go on to
+ * the next.
+ */
+ } SMARTLIST_FOREACH_END(f);
+
+ /* Did we get anything? */
+ if (descs_dumped != NULL) {
+ /* Sort the FIFO in order of increasing timestamp */
+ smartlist_sort(descs_dumped, dump_desc_compare_fifo_entries);
+
+ /* Log some stats */
+ log_info(LD_DIR,
+ "Reloaded unparseable descriptor dump FIFO with %d dump(s) "
+ "totaling %"PRIu64 " bytes",
+ smartlist_len(descs_dumped), (len_descs_dumped));
+ }
+
+ /* Free the original list */
+ SMARTLIST_FOREACH(files, char *, f, tor_free(f));
+ smartlist_free(files);
+}
+
+/** For debugging purposes, dump unparseable descriptor *<b>desc</b> of
+ * type *<b>type</b> to file $DATADIR/unparseable-desc. Do not write more
+ * than one descriptor to disk per minute. If there is already such a
+ * file in the data directory, overwrite it. */
+MOCK_IMPL(void,
+dump_desc,(const char *desc, const char *type))
+{
+ tor_assert(desc);
+ tor_assert(type);
+ size_t len;
+ /* The SHA256 of the string */
+ uint8_t digest_sha256[DIGEST256_LEN];
+ char digest_sha256_hex[HEX_DIGEST256_LEN+1];
+ /* Filename to log it to */
+ char *debugfile, *debugfile_base;
+
+ /* Get the hash for logging purposes anyway */
+ len = strlen(desc);
+ if (crypto_digest256((char *)digest_sha256, desc, len,
+ DIGEST_SHA256) < 0) {
+ log_info(LD_DIR,
+ "Unable to parse descriptor of type %s, and unable to even hash"
+ " it!", type);
+ goto err;
+ }
+
+ base16_encode(digest_sha256_hex, sizeof(digest_sha256_hex),
+ (const char *)digest_sha256, sizeof(digest_sha256));
+
+ /*
+ * We mention type and hash in the main log; don't clutter up the files
+ * with anything but the exact dump.
+ */
+ tor_asprintf(&debugfile_base,
+ DESC_DUMP_BASE_FILENAME ".%s", digest_sha256_hex);
+ debugfile = get_datadir_fname2(DESC_DUMP_DATADIR_SUBDIR, debugfile_base);
+
+ /*
+ * Check if the sandbox is active or will become active; see comment
+ * below at the log message for why.
+ */
+ if (!(sandbox_is_active() || get_options()->Sandbox)) {
+ if (len <= get_options()->MaxUnparseableDescSizeToLog) {
+ if (!dump_desc_fifo_bump_hash(digest_sha256)) {
+ /* Create the directory if needed */
+ dump_desc_create_dir();
+ /* Make sure we've got it */
+ if (have_dump_desc_dir && !problem_with_dump_desc_dir) {
+ /* Write it, and tell the main log about it */
+ write_str_to_file(debugfile, desc, 1);
+ log_info(LD_DIR,
+ "Unable to parse descriptor of type %s with hash %s and "
+ "length %lu. See file %s in data directory for details.",
+ type, digest_sha256_hex, (unsigned long)len,
+ debugfile_base);
+ dump_desc_fifo_add_and_clean(debugfile, digest_sha256, len);
+ /* Since we handed ownership over, don't free debugfile later */
+ debugfile = NULL;
+ } else {
+ /* Problem with the subdirectory */
+ log_info(LD_DIR,
+ "Unable to parse descriptor of type %s with hash %s and "
+ "length %lu. Descriptor not dumped because we had a "
+ "problem creating the " DESC_DUMP_DATADIR_SUBDIR
+ " subdirectory",
+ type, digest_sha256_hex, (unsigned long)len);
+ /* We do have to free debugfile in this case */
+ }
+ } else {
+ /* We already had one with this hash dumped */
+ log_info(LD_DIR,
+ "Unable to parse descriptor of type %s with hash %s and "
+ "length %lu. Descriptor not dumped because one with that "
+ "hash has already been dumped.",
+ type, digest_sha256_hex, (unsigned long)len);
+ /* We do have to free debugfile in this case */
+ }
+ } else {
+ /* Just log that it happened without dumping */
+ log_info(LD_DIR,
+ "Unable to parse descriptor of type %s with hash %s and "
+ "length %lu. Descriptor not dumped because it exceeds maximum"
+ " log size all by itself.",
+ type, digest_sha256_hex, (unsigned long)len);
+ /* We do have to free debugfile in this case */
+ }
+ } else {
+ /*
+ * Not logging because the sandbox is active and seccomp2 apparently
+ * doesn't have a sensible way to allow filenames according to a pattern
+ * match. (If we ever figure out how to say "allow writes to /regex/",
+ * remove this checK).
+ */
+ log_info(LD_DIR,
+ "Unable to parse descriptor of type %s with hash %s and "
+ "length %lu. Descriptor not dumped because the sandbox is "
+ "configured",
+ type, digest_sha256_hex, (unsigned long)len);
+ }
+
+ tor_free(debugfile_base);
+ tor_free(debugfile);
+
+ err:
+ return;
+}
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