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).
bdcdb0e Remove unused code under WINDWOS_PLATFORM guard (tomsmeding)
a84aa04 syncobj.h no longer defines shared_guard, so remove those define's (tomsmeding)
The removed preprocessor macro's refer to types that are not defined in
the file anymore; the only other place where shared_guard is defined is
in winobj.h, which also defines the same macro's. Therefore, this change
is safe.
(Side note is that these macro's weren't used at all anyway, but that is
orthogonal to the issue.)
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.
This allows "chain" certificates to be used with the fingerprint
whitelist option. A user can get a system-ca signature as backup while
clients explicitly whitelist the server certificate. The user specified
CA can also be combined with fingerprint whitelisting.
The former has the same behavior with single self signed certificates
while allowing the server to have separate short-term authentication
keys with long-term authorization keys.
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.
Using `verify_peer` on server side requests a certificate from the
client. If no certificate is provided, the server silently accepts the
connection and rejects if the client sends an unexpected certificate.
Adding `verify_fail_if_no_cert` has no affect on client and for server
requires that the peer sends a certificate or fails the handshake. This
is the desired behavior when the user specifies a fingerprint or CA file.
Currently a client must provide a certificate, even if the server is
configured to allow all certificates. This drops that requirement from
the client - unless the server is configured to use a CA file or
fingerprint(s) for verification - which is the standard behavior for SSL
servers.
The "system-wide" CA is not being used as a "fallback" to verify clients
before or after this patch.
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.
Manually initialize the array_entry_t iterator to ensure it points
to the correct m_array, thereby preventing a potential use-after-free
situation.
Signed-off-by: Guido Vranken <guidovranken@gmail.com>
This avoids the annoying case where the shell prints its prompt
after the last line from Monero output, causing line editing to
sometimes go wonky, for lack of a better term
RPC connections now have optional tranparent SSL.
An optional private key and certificate file can be passed,
using the --{rpc,daemon}-ssl-private-key and
--{rpc,daemon}-ssl-certificate options. Those have as
argument a path to a PEM format private private key and
certificate, respectively.
If not given, a temporary self signed certificate will be used.
SSL can be enabled or disabled using --{rpc}-ssl, which
accepts autodetect (default), disabled or enabled.
Access can be restricted to particular certificates using the
--rpc-ssl-allowed-certificates, which takes a list of
paths to PEM encoded certificates. This can allow a wallet to
connect to only the daemon they think they're connected to,
by forcing SSL and listing the paths to the known good
certificates.
To generate long term certificates:
openssl genrsa -out /tmp/KEY 4096
openssl req -new -key /tmp/KEY -out /tmp/REQ
openssl x509 -req -days 999999 -sha256 -in /tmp/REQ -signkey /tmp/KEY -out /tmp/CERT
/tmp/KEY is the private key, and /tmp/CERT is the certificate,
both in PEM format. /tmp/REQ can be removed. Adjust the last
command to set expiration date, etc, as needed. It doesn't
make a whole lot of sense for monero anyway, since most servers
will run with one time temporary self signed certificates anyway.
SSL support is transparent, so all communication is done on the
existing ports, with SSL autodetection. This means you can start
using an SSL daemon now, but you should not enforce SSL yet or
nothing will talk to you.
