The problem actually exists in two parts:
1. When sending chunks over a connection, if the queue size is
greater than N, the seed is predictable across every monero node.
>"If rand() is used before any calls to srand(), rand() behaves as if
it was seeded with srand(1). Each time rand() is seeded with the same seed, it
must produce the same sequence of values."
2. The CID speaks for itself: "'rand' should not be used for security-related
applications, because linear congruential algorithms are too easy to break."
*But* this is an area of contention.
One could argue that a CSPRNG is warranted in order to fully mitigate any
potential timing attacks based on crafting chunk responses. Others could argue
that the existing LCG, or even an MTG, would suffice (if properly seeded). As a
compromise, I've used an MTG with a full bit space. This should give a healthy
balance of security and speed without relying on the existing crypto library
(which I'm told might break on some systems since epee is not (shouldn't be)
dependent upon the existing crypto library).
fcbf7b3 p2p: propagate out peers limit to payload handler (moneromooo-monero)
098aadf p2p: close the right number of connections on setting max in/out peers (moneromooo-monero)
new cli options (RPC ones also apply to wallet):
--p2p-bind-ipv6-address (default = "::")
--p2p-bind-port-ipv6 (default same as ipv4 port for given nettype)
--rpc-bind-ipv6-address (default = "::1")
--p2p-use-ipv6 (default false)
--rpc-use-ipv6 (default false)
--p2p-require-ipv4 (default true, if ipv4 bind fails and this is
true, will not continue even if ipv6 bind
successful)
--rpc-require-ipv4 (default true, description as above)
ipv6 addresses are to be specified as "[xx:xx:xx::xx:xx]:port" except
in the cases of the cli args for bind address. For those the square
braces can be omitted.
add two RSA based ciphers for Windows/depends compatibility
also enforce server cipher ordering
also set ECDH to auto because vtnerd says it is good :)
When built with the depends system, openssl does not include any
cipher on the current whitelist, so add this one, which fixes the
problem, and does seem sensible.
It can allocate a lot when getting a lot of connections
(in particular, the stress test on windows apparently pushes
that memory to actual use, rather than just allocated)
When closing connections due to exiting, the IO service is
already gone, so the data exchange needed for a gracious SSL
shutdown cannot happen. We just close the socket in that case.
An override for the wallet to daemon connection is provided, but not for
other SSL contexts. The intent is to prevent users from supplying a
system CA as the "user" whitelisted certificate, which is less secure
since the key is controlled by a third party.
If the verification mode is `system_ca`, clients will now do hostname
verification. Thus, only certificates from expected hostnames are
allowed when SSL is enabled. This can be overridden by forcible setting
the SSL mode to autodetect.
Clients will also send the hostname even when `system_ca` is not being
performed. This leaks possible metadata, but allows servers providing
multiple hostnames to respond with the correct certificate. One example
is cloudflare, which getmonero.org is currently using.
If SSL is "enabled" via command line without specifying a fingerprint or
certificate, the system CA list is checked for server verification and
_now_ fails the handshake if that check fails. This change was made to
remain consistent with standard SSL/TLS client behavior. This can still
be overridden by using the allow any certificate flag.
If the SSL behavior is autodetect, the system CA list is still checked
but a warning is logged if this fails. The stream is not rejected
because a re-connect will be attempted - its better to have an
unverified encrypted stream than an unverified + unencrypted stream.
Specifying SSL certificates for peer verification does an exact match,
making it a not-so-obvious alias for the fingerprints option. This
changes the checks to OpenSSL which loads concatenated certificate(s)
from a single file and does a certificate-authority (chain of trust)
check instead. There is no drop in security - a compromised exact match
fingerprint has the same worse case failure. There is increased security
in allowing separate long-term CA key and short-term SSL server keys.
This also removes loading of the system-default CA files if a custom
CA file or certificate fingerprint is specified.
