SSL_read(), SSL_write() and SSL_do_handshake() can always progress the
SSL protocol instead of their normal operation, this means that we
must be checking for needless renegotiations after they return.
Introduce tor_tls_got_excess_renegotiations() which makes the
tls->server_handshake_count > 2
check for us, and use it in tor_tls_read() and tor_tls_write().
Cases that should not be handled:
* SSL_do_handshake() is only called by tor_tls_renegotiate() which is a
client-only function.
* The SSL_read() in tor_tls_shutdown() does not need to be handled,
since SSL_shutdown() will be called if SSL_read() returns an error.
Since we check for naughty renegotiations using
tor_tls_t.server_handshake_count we don't need that semi-broken
function (at least till there is a way to disable rfc5746
renegotiations too).
Switch 'server_handshake_count' from a uint8_t to 2 unsigned int bits.
Since we won't ever be doing more than 3 handshakes, we don't need the
extra space.
Toggle tor_tls_t.got_renegotiate based on the server_handshake_count.
Also assert that when we've done two handshakes as a server (the initial
SSL handshake, and the renegotiation handshake) we've just
renegotiated.
Finally, in tor_tls_read() return an error if we see more than 2
handshakes.
The renegotiation callback was called only when the first Application
Data arrived, instead of when the renegotiation took place.
This happened because SSL_read() returns -1 and sets the error to
SSL_ERROR_WANT_READ when a renegotiation happens instead of reading
data [0].
I also added a commented out aggressive assert that I won't enable yet
because I don't feel I understand SSL_ERROR_WANT_READ enough.
[0]: Look at documentation of SSL_read(), SSL_get_error() and
SSL_CTX_set_mode() (SSL_MODE_AUTO_RETRY section).
Introduce tor_tls_state_changed_callback(), which handles every SSL
state change.
The new function tor_tls_got_server_hello() is called every time we
send a ServerHello during a v2 handshake, and plays the role of the
previous tor_tls_server_info_callback() function.
Right now we can take the digests only of an RSA key, and only expect to
take the digests of an RSA key. The old tor_cert_get_id_digests() would
return a good set of digests for an RSA key, and an all-zero one for a
non-RSA key. This behavior is too error-prone: it carries the risk that
we will someday check two non-RSA keys for equality and conclude that
they must be equal because they both have the same (zero) "digest".
Instead, let's have tor_cert_get_id_digests() return NULL for keys we
can't handle, and make its callers explicitly test for NULL.
Our keys and x.509 certs are proliferating here. Previously we had:
An ID cert (using the main ID key), self-signed
A link cert (using a shorter-term link key), signed by the ID key
Once proposal 176 and 179 are done, we will also have:
Optionally, a presentation cert (using the link key),
signed by whomever.
An authentication cert (using a shorter-term ID key), signed by
the ID key.
These new keys are managed as part of the tls context infrastructure,
since you want to rotate them under exactly the same circumstances,
and since they need X509 certificates.
Also, define all commands > 128 as variable-length when using
v3 or later link protocol. Running into a var cell with an
unrecognized type is no longer a bug.
Without this patch, Tor wasn't sure whether it would be hibernating or
not, so it postponed opening listeners until after the privs had been
dropped. This doesn't work so well for low ports. Bug was introduced in
the fix for bug 2003. Fixes bug 4217, reported by Zax and katmagic.
Thanks!
One of its callers assumes a non-zero result indicates a permanent failure
(i.e. the current attempt to connect to this HS either has failed or is
doomed). The other caller only requires that this function's result
never equal -2.
Bug reported by Sebastian Hahn.
