commit 41ed9e978b77080c027e50ed831370efbeeeac37 Author: Nick Mathewson nickm@torproject.org Date: Thu Jun 1 10:04:52 2017 -0400

Regenerate RSA->ed25519 identity crosscertificate as needed --- changes/bug22466_regenerate | 8 ++++++++ src/or/routerkeys.c | 15 ++++++++++++--- 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/changes/bug22466_regenerate b/changes/bug22466_regenerate new file mode 100644 index 0000000..8dbda89 --- /dev/null +++ b/changes/bug22466_regenerate @@ -0,0 +1,8 @@ + o Minor bugfixes (link handshake): + - Lower the lifetime of the RSA->Ed25519 cross-certificate to + six months, and regenerate it when it is within one month of expiring. + Previously, we had generated this certificate at startup with + a ten-year lifetime, but that could lead to weird behavior when + Tor was started with a grossly inaccurate clock. Mitigates + bug 22466; mitigation on 0.3.0.1-alpha. + diff --git a/src/or/routerkeys.c b/src/or/routerkeys.c index 6259e3f..611ac91 100644 --- a/src/or/routerkeys.c +++ b/src/or/routerkeys.c @@ -668,6 +668,7 @@ static tor_cert_t *auth_key_cert = NULL;

static uint8_t *rsa_ed_crosscert = NULL; static size_t rsa_ed_crosscert_len = 0; +static time_t rsa_ed_crosscert_expiration = 0;

/** * Running as a server: load, reload, or refresh our ed25519 keys and @@ -699,8 +700,10 @@ load_ed_keys(const or_options_t *options, time_t now) tor_cert_free(cert); \ cert = (newval); \ } while (0) +#define HAPPENS_SOON(when, interval) \ + ((when) < now + (interval)) #define EXPIRES_SOON(cert, interval) \ - (!(cert) || (cert)->valid_until < now + (interval)) + (!(cert) || HAPPENS_SOON((cert)->valid_until, (interval)))

/* XXXX support encrypted identity keys fully */

@@ -899,14 +902,19 @@ load_ed_keys(const or_options_t *options, time_t now) if (options->command == CMD_KEYGEN) goto end;

- if (!rsa_ed_crosscert && server_mode(options)) { + if (server_mode(options) && + (!rsa_ed_crosscert || + HAPPENS_SOON(rsa_ed_crosscert_expiration, 30*86400))) { uint8_t *crosscert; + time_t expiration = now+6*30*86400; /* 6 months in the future. */ ssize_t crosscert_len = tor_make_rsa_ed25519_crosscert(&id->pubkey, get_server_identity_key(), - now+10*365*86400,/*XXXX*/ + expiration, &crosscert); + tor_free(rsa_ed_crosscert); rsa_ed_crosscert_len = crosscert_len; rsa_ed_crosscert = crosscert; + rsa_ed_crosscert_expiration = expiration; }

if (!current_auth_key || @@ -1038,6 +1046,7 @@ should_make_new_ed_keys(const or_options_t *options, const time_t now) }

#undef EXPIRES_SOON +#undef HAPPENS_SOON

#ifdef TOR_UNIT_TESTS /* Helper for unit tests: populate the ed25519 keys without saving or