This generates much of the initialisation, defaults and keyword table
code from a set of macros rather than hand coding them. These same
macros are also used to generate serialisation and deserialisation
code.
The macros are admittedly ugly but have the advantage of forcing a
good degree of consistency across places that need to stay in sync
with each other.
The new de/serialisation code is used to pass configurations across
the various sshd-* process boundaries. This removes the need to pass
around raw text configurations that need to be re-parsed as well as
eliminating some raw pointer leakage across the processes where
structures were previously clumsily serialised.
feedback/ok markus@
OpenBSD-Commit-ID: 9a5109a480637e08c290eeb82aa8ef2ca7e848ce
Previously, exchange of the initial SSH- banners was performed
by the privileged sshd-session monitor. This moves it to the
unprivileged sshd-auth subprocess, removing ~200 LoC from the
monitor's privileged attack surface.
The monitor gains a new "setcompat" RPC to allow sshd-auth to
inform it of bug compat flags picked up from the client's banner.
feedback dtucker@, ok markus@ deraadt@
OpenBSD-Commit-ID: d767eb1183630d754d521d9f0d84a6c72fbe7fc8
maximum message size of 256KB. Some people apparently have configurations
larger than this and would hit this limit.
Worse, there was no good logging that could help diagnose what was
going wrong.
So this bumps the maximum message size to 4MB and implements an early
check (usable via the sshd -t test mode) that will report it to the
user where it is hopefully more visible.
bz3808, reported by Dmitry Belyavskiy, ok dtucker@
OpenBSD-Commit-ID: 69c303fb68cbd1a4735936835d67a71e7b57f63b
Prevents problems on platforms where this isn't safe (which it's not
required to be). ok djm@
OpenBSD-Commit-ID: 8fa4ce3ad90915c925b81b99a79ab920b0523387
This splits the user authentication code from the sshd-session
binary into a separate sshd-auth binary. This will be executed by
sshd-session to complete the user authentication phase of the
protocol only.
Splitting this code into a separate binary ensures that the crucial
pre-authentication attack surface has an entirely disjoint address
space from the code used for the rest of the connection. It also
yields a small runtime memory saving as the authentication code will
be unloaded after thhe authentication phase completes.
Joint work with markus@ feedback deraadt@
Tested in snaps since last week
OpenBSD-Commit-ID: 9c3b2087ae08626ec31b4177b023db600e986d9c
problematic client behaviours, controlled by two new sshd_config(5) options:
PerSourcePenalties and PerSourcePenaltyExemptList.
When PerSourcePenalties are enabled, sshd(8) will monitor the exit
status of its child pre-auth session processes. Through the exit
status, it can observe situations where the session did not
authenticate as expected. These conditions include when the client
repeatedly attempted authentication unsucessfully (possibly indicating
an attack against one or more accounts, e.g. password guessing), or
when client behaviour caused sshd to crash (possibly indicating
attempts to exploit sshd).
When such a condition is observed, sshd will record a penalty of some
duration (e.g. 30 seconds) against the client's address. If this time
is above a minimum threshold specified by the PerSourcePenalties, then
connections from the client address will be refused (along with any
others in the same PerSourceNetBlockSize CIDR range).
Repeated offenses by the same client address will accrue greater
penalties, up to a configurable maximum. A PerSourcePenaltyExemptList
option allows certain address ranges to be exempt from all penalties.
We hope these options will make it significantly more difficult for
attackers to find accounts with weak/guessable passwords or exploit
bugs in sshd(8) itself.
PerSourcePenalties is off by default, but we expect to enable it
automatically in the near future.
much feedback markus@ and others, ok markus@
OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
binaries. This step splits sshd into a listener and a session binary. More
splits are planned.
After this changes, the listener binary will validate the configuration,
load the hostkeys, listen on port 22 and manage MaxStartups only. All
session handling will be performed by a new sshd-session binary that the
listener fork+execs.
This reduces the listener process to the minimum necessary and sets us
up for future work on the sshd-session binary.
feedback/ok markus@ deraadt@
NB. if you're updating via source, please restart sshd after installing,
otherwise you run the risk of locking yourself out.
OpenBSD-Commit-ID: 43c04a1ab96cdbdeb53d2df0125a6d42c5f19934
This adds another transport protocol extension to allow a sshd to send
SSH2_MSG_EXT_INFO during user authentication, after the server has
learned the username that is being logged in to.
This lets sshd to update the acceptable signature algoritms for public
key authentication, and allows these to be varied via sshd_config(5)
"Match" directives, which are evaluated after the server learns the
username being authenticated.
Full details in the PROTOCOL file
OpenBSD-Commit-ID: 1de7da7f2b6c32a46043d75fcd49b0cbb7db7779
dup could in theory return fd 0 although currently it doesn't in practice.
From Dmitry Belyavskiy vi github PR#238.
OpenBSD-Commit-ID: 4a95f3f7330394dffee5c749d52713cbf3b54846
The only way the if statement can be true is if both dup()s fail, and
in that case the tmp2 can never be set. Coverity CID 291805, ok djm@
OpenBSD-Commit-ID: c0d6089b3fb725015462040cd94e23237449f0c8
This adds a sshd_config ChannelTimeouts directive that allows channels that
have not seen traffic in a configurable interval to be automatically closed.
Different timeouts may be applied to session, X11, agent and TCP forwarding
channels.
Note: this only affects channels over an opened SSH connection and not
the connection itself. Most clients close the connection when their channels
go away, with a notable exception being ssh(1) in multiplexing mode.
ok markus dtucker
OpenBSD-Commit-ID: ae8bba3ed9d9f95ff2e2dc8dcadfa36b48e6c0b8
and not in the pledge(2)'d unprivileged process; fixes regression caused by
recent refactoring spotted by henning@
OpenBSD-Commit-ID: a089870b95101cd8881a2dff65b2f1627d13e88d
remove "struct ssh *" from arguments - this was only used to pass the
remote host/address. These can be passed in instead and the resulting
code is less tightly coupled to ssh_api.[ch]
ok dtucker@
OpenBSD-Commit-ID: 9d4373d013edc4cc4b5c21a599e1837ac31dda0d
log functions receive function, filename and line number of caller.
We can use this to selectively enable logging via pattern-lists.
ok markus@
OpenBSD-Commit-ID: 51a472610cbe37834ce6ce4a3f0e0b1ccc95a349
FIDO2 supports a notion of "user verification" where the user is
required to demonstrate their identity to the token before particular
operations (e.g. signing). Typically this is done by authenticating
themselves using a PIN that has been set on the token.
This adds support for generating and using user verified keys where
the verification happens via PIN (other options might be added in the
future, but none are in common use now). Practically, this adds
another key generation option "verify-required" that yields a key that
requires a PIN before each authentication.
feedback markus@ and Pedro Martelletto; ok markus@
OpenBSD-Commit-ID: 57fd461e4366f87c47502c5614ec08573e6d6a15
keys.
Previously we didn't do this because we didn't want to expose
the attack surface presented by USB and FIDO protocol handling,
but now that this is insulated behind ssh-sk-helper there is
less risk.
ok markus@
OpenBSD-Commit-ID: 77b068dd133b8d87e0f010987bd5131e640ee64c
This is populated during signature verification with additional fields
that are present in and covered by the signature. At the moment, it is
only used to record security key-specific options, especially the flags
field.
with and ok markus@
OpenBSD-Commit-ID: 338a1f0e04904008836130bedb9ece4faafd4e49
including the new U2F signatures.
Don't use sshsk_ecdsa_sign() directly, instead make it reachable via
sshkey_sign() like all other signature operations. This means that
we need to add a provider argument to sshkey_sign(), so most of this
change is mechanically adding that.
Suggested by / ok markus@
OpenBSD-Commit-ID: d5193a03fcfa895085d91b2b83d984a9fde76c8c
some arbitrary value < 0. errno is only updated in this case. Change all
(most?) callers of syscalls to follow this better, and let's see if this
strictness helps us in the future.
OpenBSD-Commit-ID: 48081f00db7518e3b712a49dca06efc2a5428075
parsing rather than make the caller do it. Saves a lot of boilerplate code.
from markus@ ok djm@
OpenBSD-Commit-ID: 576bf784f9a240f5a1401f7005364e59aed3bce9
API, started almost exactly six years ago.
This change stops including the old packet_* API by default and makes
each file that requires the old API include it explicitly. We will
commit file-by-file refactoring to remove the old API in consistent
steps.
with & ok markus@
OpenBSD-Commit-ID: 93c98a6b38f6911fd1ae025a1ec57807fb4d4ef4
Most people will 1) be using modern multi-factor authentication methods
like TOTP/OATH etc and 2) be getting support for multi-factor
authentication via PAM or BSD Auth.
[email protected]