Support PKCS#11 HSMs (like YubiKey PIV) for SSH authentication.
Use the SunPKCS11 provider as described at [1]. This provider
dynamically loads the library from the PKCS11Provider SSH configuration
and creates a Java KeyStore with that provider. A Java CallbackHandler
is needed to feed PIN prompts from the KeyStore into the JGit
CredentialsProvider framework. Because the JGit CredentialsProvider may
be specific to a SSH session but the PKCS11Provider may be used by
several sessions, the CallbackHandler needs to be configurable per
session.
PIN prompts respect the NumberOfPasswordPrompts SSH configuration. As
long as the library asks only for a PIN, we use the KeyPasswordProvider
to prompt for it. This gives automatic integration in Eclipse with the
Eclipse secure storage, so a user has even the option to store the PIN
there. (Eclipse will then ask for the secure storage master password on
first access, so the usefulness of this is debatable.)
By default the provider uses the first PKCS#11 token (slot list index
zero). This can be overridden by a non-standard PKCS11SlotListIndex
ssh configuration entry. (For OpenSSH interoperability, also set
"IgnoreUnknown PKCS11SlotListIndex" in the SSH config file then.)
Once loaded, the provider and its shared library and the keys
contained remain available until the application exits.
Manually tested using SoftHSM. See file manual_tests.txt. Kudos to
Christopher Lamb for additional manual testing with a real YubiKey,
also on Windows.[2]
[1] https://docs.oracle.com/en/java/javase/11/security/pkcs11-reference-guide1.html
[2] https://www.eclipse.org/forums/index.php/t/1113295/
Change-Id: I544c97e1e24d05e28a9f0e803fd4b9151a76ed11
Signed-off-by: Thomas Wolf <twolf@apache.org>
When authentication fails, JGit produces an exception with an error
message telling the user that it could not log in (including the host
name). The causal chain has an SshException from Apache MINA sshd with
message "No more authentication methods available".
This is not very helpful. The user was left without any indication why
authentication failed.
Include in the exception message a log of all attempted authentications.
That way, the user can see which keys were tried, in which order and
with which signature algorithms. The log also reports authentication
attempts for gssapi-with-mic or password authentication. For
keyboard-interactive Apache MINA sshd is lacking a callback interface.
The way Apache MINA sshd loads keys from files, the file names are lost
in higher layers. Add a mechanism to record on the session for each
key fingerprint the file it was loaded from, if any. That way the
exception message can refer to keys by file name, which is easier to
understand by users than the rather cryptic key fingerprints.
Bug: 571390
Change-Id: Ic4b6ce6b99f307d5e798fcc91b16b9ffd995d224
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
An SSH agent might contain keys that Apache MINA sshd cannot handle.
Pageant for instance can contain ed448 keys, which are not implemented
in OpenSSH or in Apache MINA sshd.
When an agent delivers such keys, simply skip (and log) them. That way,
we can work with the remaining keys. Otherwise a single unknown key in
the agent would break pubkey authentication.
Change-Id: I3945d932c7e64b628465004cfbaf10f4dc05f3e4
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Add parsing of the config. Implement the SSH agent protocol for adding
a key. In the pubkey authentication, add keys to the agent as soon as
they've been loaded successfully, before even attempting to use them
for authentication. OpenSSH does the same.
Bug: 577052
Change-Id: Id1c08d9676a74652256b22281c2f8fa0b6508fa6
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
If an SSH agent is used but "IdentitiesOnly yes" is set, only those
keys from the agent that correspond to one of the keys explicitly given
via an IdentityFile directive are to be used.
Implement this by filtering the list of keys obtained from the agent
against the list of IdentityFiles, each entry suffixed with ".pub".
Load the public keys from these files, and ignore all other keys from
the agent. Keys without ".pub" file are also ignored.
Apache MINA sshd has no operation to load only the public key from a
private key file, so we have to rely on *.pub files.
Bug: 577053
Change-Id: I75c2c0b3ce35781c933ec2944bd6da1b94f4caf9
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Add interfaces Connector and ConnectorFactory. A "connector" is just
something that knows how to connect to an ssh-agent and then can make
simple synchronous RPC-style requests (request-reply).
Add a way to customize an SshdSessionFactory with a ConnectorFactory.
Provide a default setup using the Java ServiceLoader mechanism to
discover an ConnectorFactory.
Implement an SshAgentClient in the internal part. Unfortunately we
cannot re-use the implementation in Apache MINA sshd: it's hard-wired
to Apache Tomcat APR, and it's also buggy.
No behavior changes yet since there is nothing that would provide an
actual ConnectorFactory. So for Apache MINA sshd, the SshAgentFactory
remains null as before.
Change-Id: I963a3d181357df2bdb66298bc702f2b9a6607a30
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Make the used KEX algorithms configurable via the ssh config. Also
implement adding algorithms not in the default set: since sshd 2.6.0
deprecated SHA1-based algorithms, it is possible that the default set
has not all available algorithms, so adding algorithms makes sense.
This enables users who have to use a git server that only supports
old SHA1-based key exchange methods to enable those methods in the
ssh config:
KexAlgorithms +diffie-hellman-group1-sha1
There are two more SHA1 algorithms that are not enabled by default:
diffie-hellman-group14-sha1 and diffie-hellman-group-exchange-sha1.
KeyAlgorithms accepts a comma-separated list of algorithm names.
Since adding algorithms is now supported, adapt the handling of
signature algorithms, too. Make sure that definitions for the KEX
exchange signature (HostKeyAlgorithms) don't conflict with the
definition for signatures for pubkey auth (PubkeyAcceptedAlgorithms).
HostKeyAlgorithms updates the signature factories set on the session
to include the default factories plus any that might have been added
via the SSH config. Move the handling of PubkeyAcceptedAlgorithms
from the client to the JGitPubkeyAuthentication, where it can be done
only if pubkey auth is attempted at all and where it can store its
adapted list of factories locally.
Bug: 574636
Change-Id: Ia5d5f174bbc8e5b41e10ec2c25216d861174e7c3
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Similar to git config file reading lock the file only when writing.
There may still be lock conflicts on writing, but those in the worst
case result in an entry not being added and thus being asked for later
again.
Because the OpenSshServerkeyDatabase and its HostKeyFiles may be (and
usually are) shared between different SSH sessions, we still need to
ensure in-process mutual exclusion.
Bug: 559548
Change-Id: I4af97628deff9eaac2520576917c856949f2680d
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Apache MINA sshd has an implementation of this, but it doesn't comply
to RFC 8308 [1] and it is buggy. (See SSHD-1141 [2].)
Add a simpler KexExtensionHandler and if the server sends extension
server-sig-algs, use its value to re-order the chosen signature
algorithms such that the algorithms the server announced as supported
are at the front.
If the server didn't tell us anything, don't do anything. RFC 8308
suggests for RSA to default to ssh-rsa, but says once rsa-sha2-* was
"widely enough" adopted, defaulting to that might be OK.
Currently we seem to be in a transition phase; Fedora 33 has already
disabled ssh-rsa by default, and openssh is about to do so. Whatever
we might do without info from the server, it'd be good for some servers
and bad for others. So don't do anything and let the user re-order via
ssh config PubkeyAcceptedAlgorithms on a case-by-case basis.
[1] https://tools.ietf.org/html/rfc8308
[2] https://issues.apache.org/jira/browse/SSHD-1141
Bug: 572056
Change-Id: I59aa691a030ffe0fae54289df00ca5c6e165817b
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Apache MINA sshd 2.6.0 appears to use only the first appropriate
public key signature algorithm for a particular key. See [1]. For
RSA keys, that is rsa-sha2-512. This breaks authentication at servers
that only know the older (and deprecated) ssh-rsa algorithm.
With PubkeyAcceptedAlgorithms, users can re-order algorithms in
the ssh config file per host, if needed. Setting
PubkeyAcceptedAlgorithms ^ssh-rsa
will put "ssh-rsa" at the front of the list of algorithms, and then
authentication at such servers with RSA keys works again.
[1] https://issues.apache.org/jira/browse/SSHD-1105
Bug: 572056
Change-Id: I86c3b93f05960c68936e80642965815926bb2532
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Use a dedicated exception class to be able to detect this case in the
SshdSessionFactory and skip the generic SshException in that case.
Change-Id: I2a0bacf47bae82f154a0f4e79efbb2af2a17d0cf
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
This is useful to access git repositories behind a bastion server
(jump host).
Add a constant for the config; rewrite the whole connection initiation
to parse the value and (recursively) set up the chain of hops. Add
tests for a single hop and two different ways to configure a two-hop
chain.
The connection timeout applies to each hop in the chain individually.
Change-Id: Idd25af95aa2ec5367404587e4e530b0663c03665
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
When exceptions occur very early in the SSH connection setup, it's
possible that an exception gets lost. A subsequent authentication
attempt may then never be notified of the failure, and then wait
indefinitely or until its timeout expires.
This is caused by race conditions in sshd. The issue has been reported
upstream as SSHD-1050,[1] but will be fixed at the earliest in sshd
2.6.0.
[1] https://issues.apache.org/jira/projects/SSHD/issues/SSHD-1050
Bug: 565394
Change-Id: If9b62839db38f9e59a5e1137c2257039ba82de98
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Motivation: JSch serves as 'default' implementations of the SSH
transport. If a client application does not use it then there is no need
to pull in this dependency.
Move the classes depending on JSch to an OSGi fragment extending the
org.eclipse.jgit bundle and keep them in the same package as before
since moving them to another package would break API. Defer moving them
to a separate package to the next major release.
Add a new feature org.eclipse.jgit.ssh.jsch feature to enable
installation. With that users can now decide which of the ssh client
integrations (JCraft JSch or Apache Mina SSHD) they want to install.
We will remove the JCraft JSch integration in a later step due to the
reasons discussed in bug 520927.
Bug: 553625
Change-Id: I5979c8a9dbbe878a2e8ac0fbfde7230059d74dc2
Also-by: Michael Dardis <git@md-5.net>
Signed-off-by: Michael Dardis <git@md-5.net>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Signed-off-by: David Ostrovsky <david@ostrovsky.org>
RFC 4253 section 4.2 allows an ssh server to send additional lines
before its server identification string. Apache MINA sshd enforces
for these lines the constraints specified for the server identification
line, too: no NUL characters and not longer than 255 characters. That
is too strict. RFC 4253 doesn't mandate this, and it also doesn't
make sense given the rationale for these lines in RFC 4253: a TCP
wrapper may not be aware of SSH restrictions, and may not adhere to
these constraints.
Be more lenient when parsing the server's protocol version. Allow
NULs and longer lines in the preamble, and also handle line endings
more leniently. Only enforce the restrictions for the actual server
identification line.
Bug: 545939
Change-Id: I75955e9d8a8daef7c04fc0f39539c2ee93514e1c
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Don't use the ~/.ssh directory as cache key for the key provider
but the configured paths of the default keys. Otherwise changes
in that list of paths are not picked up.
This is in particular a problem for EGit, where the user can modify
this list of keys interactively in the preferences. Without this
change, Eclipse needs to be restarted to pick up such changes.
Bug: 542845
Change-Id: I63432fb10729a90b3c5e14f13e39bf482aef811b
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Add tests for password and keyboard-interactive authentication.
Implement password authentication; the default provided by sshd
is non-interactive, which is not useful for JGit.
Make sure the CredentialsProvider gets reset on successive password
retrieval attempts. Otherwise it might always return the same non-
accepted password from a secure storage. (That one was discovered
by actually trying this via EGit; the JGit tests don't catch this.)
Change the default order of authentication mechanisms to prefer
password over keyboard-interactive. This is a mitigation for upstream
bug SSHD-866.[1]
Also include a fix for upstream bug SSHD-867.[2]
[1] https://issues.apache.org/jira/projects/SSHD/issues/SSHD-866
[2] https://issues.apache.org/jira/projects/SSHD/issues/SSHD-867
Bug: 520927
Change-Id: I423e548f06d3b51531016cf08938c8bd7acaa2a9
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
This is not about the ssh config ProxyCommand but about programmatic
support for HTTP and SOCKS5 proxies. Eclipse allows the user to
specify such proxies, and JSch at least contains code to connect
through proxies. So our Apache MINA sshd client also should be able
to do this.
Add interfaces and provide two implementations for HTTP and SOCKS5
proxies. Adapt the core code to be able to deal with proxy connections
at all. The built-in client-side support for this in sshd 2.0.0 is
woefully inadequate.
Tested manually by running proxies and then fetching various real-
world repositories via these proxies from different servers. Proxies
tested: ssh -D (SOCKS, anonymous), tinyproxy (HTTP, anonymous), and
3proxy (SOCKS & HTTP, username-password authentication). The GSS-API
authentication is untested since I have no Kerberos setup.
Bug: 520927
Change-Id: I1a5c34687d439b3ef8373c5d58e24004f93e63ae
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
sshd only asks exactly once for the password. C.f. upstream issue
SSHD-850.[1] So we have to work around this limitation for now.
Once we move to sshd > 2.1.0, this can be simplified somewhat.
[1] https://issues.apache.org/jira/browse/SSHD-850
Bug: 520927
Change-Id: Id65650228486c5ed30affa9c62eac982e01ae207
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
By default sshd will use its default built-in list, which matches
the one of openssh (as far as the algorithms exist in sshd at all).
But it doesn't handle HostKeyAlgorithms from the ssh config at all.
Implement this as in openssh, including the '+' and '-' modifiers
and reordering the default if there are known host keys for a
server already.
Add tests for the reordering.
Also use a more robust reader for the known hosts file. The default
aborts on the first error.
Bug: 520927
Change-Id: Ib1684440bfe2e96140536aa1a93c4bd4a0d35916
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Set the internal property on the session as defined in the ssh config.
Note that NumberOfPasswordPrompts in openssh applies independently to
both user logins in keyboard-interactive authentication _and_ to
passphrases for identity files (encrypted keys). Apache MINA sshd uses
the setting only for keyboard-interactive authentication, but not for
identity file passphrase prompts. For identity files, it asks exactly
once. This has been reported as issue SSHD-850 upstream.[1]
[1] https://issues.apache.org/jira/browse/SSHD-850
Bug: 520927
Change-Id: I390ffe9e1c52b96d3e8e28fd8edbdc73dde9edb4
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
sshd does support gssapi-with-mic on the server side, but has no
built-in client-side support for this authentication mechanism.
Add our own implementation for it, following RFC 4462.[1] To avoid
needlessly re-trying mechanisms that aren't even configured on the
client, we disable mechanisms that fail on the very first attempt
to use them.
Since we have no real Kerberos5 test setup, this cannot be fully
tested in CI. The disabling of the authentication mechanism and
that it is skipped when not successful _is_ tested.
[1] https://www.ietf.org/rfc/rfc4462.txt
Bug: 520927
Change-Id: I5d0cdb14103588a57c52f927df541b589ab88d88
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Add a new ssh client implementation based on Apach MINA sshd 2.0.0.
This implementation uses JGit's own config file parser and host entry
resolver. Code inspection of the Apache MINA implementation revealed
a few bugs or idiosyncrasies that immediately would re-introduce bugs
already fixed in the past in JGit.
Apache MINA sshd is not without quirks either, and I had to configure
and override more than I had expected. But at least it was all doable
in clean ways.
Apache MINA boasts support for Bouncy Castle, so in theory this should
open the way to using more ssh key algorithms, such as ed25519.
The implementation is in a separate bundle and is still not used in
the core org.eclipse.jgit bundle. The tests re-use the ssh tests from
the core test bundle.
Bug: 520927
Change-Id: Ib35e73c35799140fe050d1ff4fb18d0d3596580e
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Thomas Wolf