diff options
Diffstat (limited to 'src/or')
| -rw-r--r-- | src/or/include.am | 2 | ||||
| -rw-r--r-- | src/or/keypin.c | 391 | ||||
| -rw-r--r-- | src/or/keypin.h | 44 |
3 files changed, 437 insertions, 0 deletions
diff --git a/src/or/include.am b/src/or/include.am index a85b0dde05..68f091b3a9 100644 --- a/src/or/include.am +++ b/src/or/include.am @@ -53,6 +53,7 @@ LIBTOR_A_SOURCES = \ src/or/entrynodes.c \ src/or/ext_orport.c \ src/or/hibernate.c \ + src/or/keypin.c \ src/or/main.c \ src/or/microdesc.c \ src/or/networkstatus.c \ @@ -161,6 +162,7 @@ ORHEADERS = \ src/or/geoip.h \ src/or/entrynodes.h \ src/or/hibernate.h \ + src/or/keypin.h \ src/or/main.h \ src/or/microdesc.h \ src/or/networkstatus.h \ diff --git a/src/or/keypin.c b/src/or/keypin.c new file mode 100644 index 0000000000..87e49cdff6 --- /dev/null +++ b/src/or/keypin.c @@ -0,0 +1,391 @@ +/* Copyright (c) 2014, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +#define KEYPIN_PRIVATE + +#include "orconfig.h" +#include "compat.h" +#include "crypto.h" +#include "di_ops.h" +#include "ht.h" +#include "keypin.h" +#include "siphash.h" +#include "torint.h" +#include "torlog.h" +#include "util.h" + +#ifdef HAVE_UNISTD_H +#include <unistd.h> +#endif +#ifdef HAVE_FCNTL_H +#include <fcntl.h> +#endif + +#ifdef _WIN32 +#include <io.h> +#endif + +/** + * @file keypin.c + * @brief Key-pinning for RSA and Ed25519 identity keys at directory + * authorities. + * + * This module implements a key-pinning mechanism to ensure that it's safe + * to use RSA keys as identitifers even as we migrate to Ed25519 keys. It + * remembers, for every Ed25519 key we've seen, what the associated Ed25519 + * key is. This way, if we see a different Ed25519 key with that RSA key, + * we'll know that there's a mismatch. + * + * We persist these entries to disk using a simple format, where each line + * has a base64-encoded RSA SHA1 hash, then a base64-endoded Ed25519 key. + * Empty lines, misformed lines, and lines beginning with # are + * ignored. Lines beginning with @ are reserved for future extensions. + */ + +static int keypin_journal_append_entry(const uint8_t *rsa_id_digest, + const uint8_t *ed25519_id_key); + +static HT_HEAD(rsamap, keypin_ent_st) the_rsa_map = HT_INITIALIZER(); +static HT_HEAD(edmap, keypin_ent_st) the_ed_map = HT_INITIALIZER(); + +/** Hashtable helper: compare two keypin table entries and return true iff + * they have the same RSA key IDs. */ +static INLINE int +keypin_ents_eq_rsa(const keypin_ent_t *a, const keypin_ent_t *b) +{ + return tor_memeq(a->rsa_id, b->rsa_id, sizeof(a->rsa_id)); +} + +/** Hashtable helper: hash a keypin table entries based on its RSA key ID */ +static INLINE unsigned +keypin_ent_hash_rsa(const keypin_ent_t *a) +{ +return (unsigned) siphash24g(a->rsa_id, sizeof(a->rsa_id)); +} + +/** Hashtable helper: compare two keypin table entries and return true iff + * they have the same ed25519 keys */ +static INLINE int +keypin_ents_eq_ed(const keypin_ent_t *a, const keypin_ent_t *b) +{ + return tor_memeq(a->ed25519_key, b->ed25519_key, sizeof(a->ed25519_key)); +} + +/** Hashtable helper: hash a keypin table entries based on its ed25519 key */ +static INLINE unsigned +keypin_ent_hash_ed(const keypin_ent_t *a) +{ +return (unsigned) siphash24g(a->ed25519_key, sizeof(a->ed25519_key)); +} + +HT_PROTOTYPE(rsamap, keypin_ent_st, rsamap_node, keypin_ent_hash_rsa, + keypin_ents_eq_rsa); +HT_GENERATE2(rsamap, keypin_ent_st, rsamap_node, keypin_ent_hash_rsa, + keypin_ents_eq_rsa, 0.6, tor_reallocarray, tor_free_); + +HT_PROTOTYPE(edmap, keypin_ent_st, edmap_node, keypin_ent_hash_ed, + keypin_ents_eq_ed); +HT_GENERATE2(edmap, keypin_ent_st, edmap_node, keypin_ent_hash_ed, + keypin_ents_eq_ed, 0.6, tor_reallocarray, tor_free_); + +/** + * Check whether we already have an entry in the key pinning table for a + * router with RSA ID digest <b>rsa_id_digest</b> or for ed25519 key + * <b>ed25519_id_key</b>. If we have an entry that matches both keys, + * return KEYPIN_FOUND. If we find an entry that matches one key but + * not the other, return KEYPIN_MISMATCH. If we have no entry for either + * key, add such an entry to the table and return KEYPIN_ADDED. + */ +int +keypin_check_and_add(const uint8_t *rsa_id_digest, + const uint8_t *ed25519_id_key) +{ + keypin_ent_t search, *ent; + memset(&search, 0, sizeof(search)); + memcpy(search.rsa_id, rsa_id_digest, sizeof(search.rsa_id)); + memcpy(search.ed25519_key, ed25519_id_key, sizeof(search.ed25519_key)); + + /* Search by RSA key digest first */ + ent = HT_FIND(rsamap, &the_rsa_map, &search); + if (ent) { + tor_assert(fast_memeq(ent->rsa_id, rsa_id_digest, sizeof(ent->rsa_id))); + if (tor_memeq(ent->ed25519_key, ed25519_id_key,sizeof(ent->ed25519_key))) { + return KEYPIN_FOUND; /* Match on both keys. Great. */ + } else { + return KEYPIN_MISMATCH; /* Found RSA with different Ed key */ + } + } + + /* See if we know a different RSA key for this ed key */ + ent = HT_FIND(edmap, &the_ed_map, &search); + if (ent) { + /* If we got here, then the ed key matches and the RSA doesn't */ + tor_assert(fast_memeq(ent->ed25519_key, ed25519_id_key, + sizeof(ent->ed25519_key))); + tor_assert(fast_memneq(ent->rsa_id, rsa_id_digest, sizeof(ent->rsa_id))); + return KEYPIN_MISMATCH; + } + + /* Okay, this one is new to us. */ + ent = tor_memdup(&search, sizeof(search)); + keypin_add_entry_to_map(ent); + keypin_journal_append_entry(rsa_id_digest, ed25519_id_key); + return KEYPIN_ADDED; +} + +/** + * Helper: add <b>ent</b> to the hash tables. + */ +MOCK_IMPL(STATIC void, +keypin_add_entry_to_map, (keypin_ent_t *ent)) +{ + HT_INSERT(rsamap, &the_rsa_map, ent); + HT_INSERT(edmap, &the_ed_map, ent); +} + +/** + * Check whether we already have an entry in the key pinning table for a + * router with RSA ID digest <b>rsa_id_digest</b>. If we have no such entry, + * return KEYPIN_NOT_FOUND. If we find an entry that matches the RSA key but + * which has an ed25519 key, return KEYPIN_MISMATCH. + */ +int +keypin_check_lone_rsa(const uint8_t *rsa_id_digest) +{ + keypin_ent_t search, *ent; + memset(&search, 0, sizeof(search)); + memcpy(search.rsa_id, rsa_id_digest, sizeof(search.rsa_id)); + + /* Search by RSA key digest first */ + ent = HT_FIND(rsamap, &the_rsa_map, &search); + if (ent) { + return KEYPIN_MISMATCH; + } else { + return KEYPIN_NOT_FOUND; + } +} + +/** Open fd to the keypinning journal file. */ +static int keypin_journal_fd = -1; + +/** Open the key-pinning journal to append to <b>fname</b>. Return 0 on + * success, -1 on failure. */ +int +keypin_open_journal(const char *fname) +{ + /* O_SYNC ??*/ + int fd = tor_open_cloexec(fname, O_WRONLY|O_CREAT, 0600); + if (fd < 0) + goto err; + + if (tor_fd_seekend(fd) < 0) + goto err; + + /* Add a newline in case the last line was only partially written */ + if (write(fd, "\n", 1) < 1) + goto err; + + /* Add something about when we opened this file. */ + char buf[80]; + char tbuf[ISO_TIME_LEN+1]; + format_iso_time(tbuf, approx_time()); + tor_snprintf(buf, sizeof(buf), "@opened-at %s\n", tbuf); + if (write_all(fd, buf, strlen(buf), 0) < 0) + goto err; + + keypin_journal_fd = fd; + return 0; + err: + if (fd >= 0) + close(fd); + return -1; +} + +/** Close the keypinning journal file. */ +int +keypin_close_journal(void) +{ + if (keypin_journal_fd >= 0) + close(keypin_journal_fd); + keypin_journal_fd = -1; + return 0; +} + +/** Length of a keypinning journal line, including terminating newline. */ +#define JOURNAL_LINE_LEN (BASE64_DIGEST_LEN + BASE64_DIGEST256_LEN + 2) + +/** Add an entry to the keypinning journal to map <b>rsa_id_digest</b> and + * <b>ed25519_id_key</b>. */ +static int +keypin_journal_append_entry(const uint8_t *rsa_id_digest, + const uint8_t *ed25519_id_key) +{ + if (keypin_journal_fd == -1) + return -1; + char line[JOURNAL_LINE_LEN]; + digest_to_base64(line, (const char*)rsa_id_digest); + line[BASE64_DIGEST_LEN] = ' '; + digest256_to_base64(line + BASE64_DIGEST_LEN + 1, + (const char*)ed25519_id_key); + line[BASE64_DIGEST_LEN+1+BASE64_DIGEST256_LEN] = '\n'; + + if (write_all(keypin_journal_fd, line, JOURNAL_LINE_LEN, 0)<0) { + log_warn(LD_DIRSERV, "Error while adding a line to the key-pinning " + "journal: %s", strerror(errno)); + keypin_close_journal(); + return -1; + } + + return 0; +} + +/** Load a journal from the <b>size</b>-byte region at <b>data</b>. Return 0 + * on success, -1 on failure. */ +STATIC int +keypin_load_journal_impl(const char *data, size_t size) +{ + const char *start = data, *end = data + size, *next; + + int n_corrupt_lines = 0; + int n_entries = 0; + int n_duplicates = 0; + int n_conflicts = 0; + + for (const char *cp = start; cp < end; cp = next) { + const char *eol = memchr(cp, '\n', end-cp); + const char *eos = eol ? eol : end; + const size_t len = eos - cp; + + next = eol ? eol + 1 : end; + + if (len == 0) { + continue; + } + + if (*cp == '@') { + /* Lines that start with @ are reserved. Ignore for now. */ + continue; + } + if (*cp == '#') { + /* Lines that start with # are comments. */ + continue; + } + + /* Is it the right length? (The -1 here is for the newline.) */ + if (len != JOURNAL_LINE_LEN - 1) { + /* Lines with a bad length are corrupt unless they are empty. + * Ignore them either way */ + for (const char *s = cp; s < eos; ++s) { + if (! TOR_ISSPACE(*s)) { + ++n_corrupt_lines; + break; + } + } + continue; + } + + keypin_ent_t *ent = keypin_parse_journal_line(cp); + + if (ent == NULL) { + ++n_corrupt_lines; + continue; + } + + const keypin_ent_t *ent2; + if ((ent2 = HT_FIND(rsamap, &the_rsa_map, ent))) { + if (fast_memeq(ent2->ed25519_key, ent->ed25519_key, DIGEST256_LEN)) { + ++n_duplicates; + } else { + ++n_conflicts; + } + tor_free(ent); + continue; + } else if (HT_FIND(edmap, &the_ed_map, ent)) { + tor_free(ent); + ++n_conflicts; + continue; + } + + keypin_add_entry_to_map(ent); + ++n_entries; + } + + int severity = (n_corrupt_lines || n_duplicates) ? LOG_WARN : LOG_INFO; + tor_log(severity, LD_DIRSERV, + "Loaded %d entries from keypin journal. " + "Found %d corrupt lines, %d duplicates, and %d conflicts.", + n_entries, n_corrupt_lines, n_duplicates, n_conflicts); + + return 0; +} + +/** + * Load a journal from the file called <b>fname</b>. Return 0 on success, + * -1 on failure. + */ +int +keypin_load_journal(const char *fname) +{ + tor_mmap_t *map = tor_mmap_file(fname); + if (!map) { + if (errno == ENOENT) + return 0; + else + return -1; + } + int r = keypin_load_journal_impl(map->data, map->size); + tor_munmap_file(map); + return r; +} + +/** Parse a single keypinning journal line entry from <b>cp</b>. The input + * does not need to be NUL-terminated, but it <em>does</em> need to have + * KEYPIN_JOURNAL_LINE_LEN -1 bytes available to read. Return a new entry + * on success, and NULL on failure. + */ +STATIC keypin_ent_t * +keypin_parse_journal_line(const char *cp) +{ + /* XXXX assumes !USE_OPENSSL_BASE64 */ + keypin_ent_t *ent = tor_malloc_zero(sizeof(keypin_ent_t)); + + if (base64_decode((char*)ent->rsa_id, sizeof(ent->rsa_id), + cp, BASE64_DIGEST_LEN) != DIGEST_LEN || + cp[BASE64_DIGEST_LEN] != ' ' || + base64_decode((char*)ent->ed25519_key, sizeof(ent->ed25519_key), + cp+BASE64_DIGEST_LEN+1, BASE64_DIGEST256_LEN) != DIGEST256_LEN) { + tor_free(ent); + return NULL; + } else { + return ent; + } +} + +/** Remove all entries from the keypinning table.*/ +void +keypin_clear(void) +{ + int bad_entries = 0; + { + keypin_ent_t **ent, **next, *this; + for (ent = HT_START(rsamap, &the_rsa_map); ent != NULL; ent = next) { + this = *ent; + next = HT_NEXT_RMV(rsamap, &the_rsa_map, ent); + + keypin_ent_t *other_ent = HT_REMOVE(edmap, &the_ed_map, this); + bad_entries += (other_ent != this); + + tor_free(this); + } + } + bad_entries += HT_SIZE(&the_ed_map); + + HT_CLEAR(edmap,&the_ed_map); + HT_CLEAR(rsamap,&the_rsa_map); + + if (bad_entries) { + log_warn(LD_BUG, "Found %d discrepencies in the the keypin database.", + bad_entries); + } +} + diff --git a/src/or/keypin.h b/src/or/keypin.h new file mode 100644 index 0000000000..16a0775208 --- /dev/null +++ b/src/or/keypin.h @@ -0,0 +1,44 @@ +/* Copyright (c) 2014, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +#ifndef TOR_KEYPIN_H +#define TOR_KEYPIN_H + +#include "testsupport.h" + +int keypin_check_and_add(const uint8_t *rsa_id_digest, + const uint8_t *ed25519_id_key); + +int keypin_open_journal(const char *fname); +int keypin_close_journal(void); +int keypin_load_journal(const char *fname); +void keypin_clear(void); +int keypin_check_lone_rsa(const uint8_t *rsa_id_digest); + +#define KEYPIN_FOUND 0 +#define KEYPIN_ADDED 1 +#define KEYPIN_MISMATCH -1 +#define KEYPIN_NOT_FOUND -2 + +#ifdef KEYPIN_PRIVATE + +/** + * In-memory representation of a key-pinning table entry. + */ +typedef struct keypin_ent_st { + HT_ENTRY(keypin_ent_st) rsamap_node; + HT_ENTRY(keypin_ent_st) edmap_node; + /** SHA1 hash of the RSA key */ + uint8_t rsa_id[DIGEST_LEN]; + /** Ed2219 key. */ + uint8_t ed25519_key[DIGEST256_LEN]; +} keypin_ent_t; + +STATIC keypin_ent_t * keypin_parse_journal_line(const char *cp); +STATIC int keypin_load_journal_impl(const char *data, size_t size); + +MOCK_DECL(STATIC void, keypin_add_entry_to_map, (keypin_ent_t *ent)); +#endif + +#endif + |