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>
sshd: try all configured signature algorithms for a key
For RSA keys, there may be several configured signature algorithms:
rsa-sha2-512, rsa-sha2-256, and ssh-rsa. Upstream sshd has bug
SSHD-1105 [1] and always and unconditionally uses only the first
configured algorithm. With the default order, this means that it cannot
connect to a server that knows only ssh-rsa, like for instance Apache
MINA sshd servers older than 2.6.0.
This affects for instance bitbucket.org or also AWS Code Commit.
Re-introduce our own pubkey authenticator that fixes this.
Note that a server may impose a penalty (back-off delay) for subsequent
authentication attempts with signature algorithms unknown to the server.
In such cases, users can re-order the signature algorithm list via the
PubkeyAcceptedAlgorithms (formerly PubkeyAcceptedKeyTypes) ssh config.
[1] https://issues.apache.org/jira/browse/SSHD-1105
Bug: 572056
Change-Id: I7fb9c759ab6532e5f3b6524e9084085ddb2f30d6
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>
Migrate to Apache MINA sshd 2.6.0 and Orbit I20210203173513
Re-enable DSA, DSA_CERT, and RSA_CERT public key authentication.
DSA is discouraged for a long time already, but it might still be
way too disruptive to completely drop it. RSA is discouraged for
far less long, and dropping that would be really disruptive.
Adapt to the changed property handling. Remove work-arounds for
shortcomings of earlier sshd versions.
Use Orbit I20210203173513, which includes sshd 2.6.0. This also bumps
apache.httpclient to 4.5.13 and apache.httpcore to 4.4.14.
Change-Id: I2d24a1ce4cc9f616a94bb5c4bdaedbf20dc6638e
Signed-off-by: David Ostrovsky <david@ostrovsky.org>
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Make all transports request protocol V2 when fetching. Depending on
the transport, set the GIT_PROTOCOL environment variable (file and
ssh), pass the Git-Protocol header (http), or set the hidden
"\0version=2\0" (git anon). We'll fall back to V0 if the server
doesn't reply with a version 2 answer.
A user can control which protocol the client requests via the git
config protocol.version; if not set, JGit requests protocol V2 for
fetching. Pushing always uses protocol V0 still.
In the API, there is only a new Transport.openFetch() version that
takes a collection of RefSpecs plus additional patterns to construct
the Ref prefixes for the "ls-refs" command in protocol V2. If none
are given, the server will still advertise all refs, even in protocol
V2.
BasePackConnection.readAdvertisedRefs() handles falling back to
protocol V0. It newly returns true if V0 was used and the advertised
refs were read, and false if V2 is used and an explicit "ls-refs" is
needed. (This can't be done transparently inside readAdvertisedRefs()
because a "stateless RPC" transport like TransportHttp may need to
open a new connection for writing.)
BasePackFetchConnection implements the changes needed for the protocol
V2 "fetch" command (stateless protocol, simplified ACK handling,
delimiters, section headers).
In TransportHttp, change readSmartHeaders() to also recognize the
"version 2" packet line as a valid smart server indication.
Adapt tests, and run all the HTTP tests not only with both HTTP
connection factories (JDK and Apache HttpClient) but also with both
protocol V0 and V2. The SSH tests are much slower and much more
focused on the SSH protocol and SSH key handling. Factor out two
very simple cloning and pulling tests and make those run with
protocol V2.
Bug: 553083
Change-Id: I357c7f5daa7efb2872f1c64ee6f6d54229031ae1
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
[spotbugs] Fix potential NPE in OpenSshServerKeyDatabase
If oldLine is null #updateModifiedServerKey shouldn't be called since it
would derefence it. Spotbugs raised this as problem
RCN_REDUNDANT_NULLCHECK_WOULD_HAVE_BEEN_A_NPE. Fix it by checking if
oldLine is null before calling #updateModifiedServerKey.
Change-Id: I8a2000492986e52ce7dbe25f48b321c05fd371e4
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Revert "Client-side protocol V2 support for fetching"
This reverts commit f802f06e7f.
I had misunderstood how protocol V2 works. This implementation only
works if the negotiation during fetch is done in one round.
Fixing this is substantial work in BasePackFetchConnection. Basically
I think I'd have to change back negotiate to the V0 version, and have
a doFetch() that does
if protocol V2
doFetchV2()
else
doFetchV0()
with doFetchV0 the old code, and doFetchV2 completely new.
Plus there would need to be a HTTP test case requiring several
negotiation rounds.
This is a couple of days work at least, and I don't know when I will
have the time to revisit this. So although the rest of the code is
fine I prefer to back this out completely and not leave a only half
working implementation in the code for an indeterminate time.
Bug: 553083
Change-Id: Icbbbb09882b3b83f9897deac4a06d5f8dc99d84e
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Make all transports request protocol V2 when fetching. Depending on
the transport, set the GIT_PROTOCOL environment variable (file and
ssh), pass the Git-Protocol header (http), or set the hidden
"\0version=2\0" (git anon). We'll fall back to V0 if the server
doesn't reply with a version 2 answer.
A user can control which protocol the client requests via the git
config protocol.version; if not set, JGit requests protocol V2 for
fetching. Pushing always uses protocol V0 still.
In the API, there is only a new Transport.openFetch() version that
takes a collection of RefSpecs plus additional patterns to construct
the Ref prefixes for the "ls-refs" command in protocol V2. If none
are given, the server will still advertise all refs, even in protocol
V2.
BasePackConnection.readAdvertisedRefs() handles falling back to
protocol V0. It newly returns true if V0 was used and the advertised
refs were read, and false if V2 is used and an explicit "ls-refs" is
needed. (This can't be done transparently inside readAdvertisedRefs()
because a "stateless RPC" transport like TransportHttp may need to
open a new connection for writing.)
BasePackFetchConnection implements the changes needed for the protocol
V2 "fetch" command (simplified ACK handling, delimiters, section
headers).
In TransportHttp, change readSmartHeaders() to also recognize the
"version 2" packet line as a valid smart server indication.
Adapt tests, and run all the HTTP tests not only with both HTTP
connection factories (JDK and Apache HttpClient) but also with both
protocol V0 and V2. Do the same for the SSH transport tests.
Bug: 553083
Change-Id: Ice9866aa78020f5ca8f397cde84dc224bf5d41b4
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Support "http.userAgent" and "http.extraHeader" from the git config
Validate the extra headers and log but otherwise ignore invalid
headers. An empty http.extraHeader starts the list afresh.
The http.userAgent is restricted to printable 7-bit ASCII, other
characters are replaced by '.'.
Moves a support method from the ssh.apache bundle to HttpSupport in
the main JGit bundle.
Bug:541500
Change-Id: Id2d8df12914e2cdbd936ff00dc824d8f871bd580
Signed-off-by: James Wynn <james@jameswynn.com>
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
sshd: better error report when user cancels authentication
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>
Close the channel gracefully to give the server a chance to clean up
properly on its side.
Bug: 565854
Change-Id: Iedda5af3b97c8321f08f7ce854274cbb30e401de
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Update javadoc for RemoteSession and SshSessionFactory
The timeout on RemoteSession.exec() cannot be a timeout for the
whole command. It can only be a timeout for setting up the process;
after that it's the application's responsibility to implement some
timeout for the execution of the command, for instance by calling
Process.waitFor(int, TimeUnit) or through other means.
Sessions returned by an SshSessionFactory are already connected and
authenticated -- they must be, because RemoteSession offers no
operations for connecting or authenticating a session.
Change the implementation of SshdExecProcess.waitFor() to wait
indefinitely. The original implementation used the timeout from
RemoteSession.exec() because of that erroneous javadoc.
Change-Id: I3c7ede24ab66d4c81f72d178ce5012d383cd826e
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
sshd: work around a race condition in Apache MINA sshd 2.4.0/2.5.x
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>
sshd: store per-session data on the sshd session object
Don't store session properties on the client but in a dedicated
per-session object that is attached to the sshd session.
Also make sure that each sshd session gets its own instance of
IdentityPasswordProvider that asks for passphrases of encrypted
private keys, and also store it on the session itself.
Bug: 563380
Change-Id: Ia88bf9f91cd22b5fd32b5972d8204d60f2de56bf
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>
Thomas Wolf
Matthias Sohn
David Ostrovsky
James Wynn