Fixed NULL pointer deref in the GENERAL_NAME_cmp function This
function could crash if both GENERAL_NAMEs contain an EDIPARTYNAME.
If an attacker can control both items being compared then this
could lead to a possible denial of service attack. OpenSSL itself
uses the GENERAL_NAME_cmp function for two purposes:
Comparing CRL distribution point names between an available CRL
and a CRL distribution point embedded in an X509 certificate When
verifying that a timestamp response token signer matches the
timestamp authority name (exposed via the API functions
TS_RESP_verify_response and TS_RESP_verify_token) (CVE-2020-1971)
Matt Caswell
Changes between 1.1.1g and 1.1.1h [22 Sep 2020]
Certificates with explicit curve parameters are now disallowed in
verification chains if the X509_V_FLAG_X509_STRICT flag is used.
Tomas Mraz
The 'MinProtocol' and 'MaxProtocol' configuration commands now
silently ignore TLS protocol version bounds when configuring
DTLS-based contexts, and conversely, silently ignore DTLS protocol
version bounds when configuring TLS-based contexts. The commands
can be repeated to set bounds of both types. The same applies with
the corresponding "min_protocol" and "max_protocol" command-line
switches, in case some application uses both TLS and DTLS.
SSL_CTX instances that are created for a fixed protocol version
(e.g. TLSv1_server_method()) also silently ignore version bounds.
Previously attempts to apply bounds to these protocol versions
would result in an error. Now only the "version-flexible" SSL_CTX
instances are subject to limits in configuration files in command-line
options.
Viktor Dukhovni
Handshake now fails if Extended Master Secret extension is dropped
on renegotiation.
Tomas Mraz
The Oracle Developer Studio compiler will start reporting deprecated
APIs
mirrors listed at https://www.openssh.com/.
OpenSSH is a 100% complete SSH protocol 2.0 implementation and
includes sftp client and server support.
Once again, we would like to thank the OpenSSH community for their
continued support of the project, especially those who contributed
code or patches, reported bugs, tested snapshots or donated to the
project. More information on donations may be found at:
https://www.openssh.com/donations.html
Future deprecation notice
=========================
It is now possible[1] to perform chosen-prefix attacks against the
SHA-1 algorithm for less than USD$50K. For this reason, we will be
disabling the "ssh-rsa" public key signature algorithm by default in a
near-future release.
This algorithm is unfortunately still used widely despite the
existence of better alternatives, being the only remaining public key
signature algorithm specified by the original SSH RFCs.
The better alternatives include:
* The RFC8332 RSA SHA-2 signature algorithms rsa-sha2-256/512. These
algorithms have the advantage of using the same key type as
"ssh-rsa" but use the safe SHA-2 hash algorithms. These have been
supported since OpenSSH 7.2 and are already used by default if the
client and server support them.
* The ssh-ed25519 signature algorithm. It has been supported in
OpenSSH since release 6.5.
* The RFC5656 ECDSA algorithms: ecdsa-sha2-nistp256/384/521. These
have been supported by OpenSSH since release 5.7.
To check whether a server is using the weak ssh-rsa public key
algorithm, for host authentication, try to connect to it after
removing the ssh-rsa algorithm from ssh(1)'s allowed list:
ssh -oHostKeyAlgorithms=-ssh-rsa user@host
If the host key verification fails and no other supported host key
types are available, the server software on that host should be
upgraded.
We intend to enable UpdateHostKeys by default in the next OpenSSH
release. This will assist the client by automatically migrating to
better algorithms. Users may consider enabling this option manually.
[1] "SHA-1 is a Shambles: First Chosen-Prefix Collision on SHA-1 and
Application to the PGP Web of Trust" Leurent, G and Peyrin, T
(2020) https://eprint.iacr.org/2020/014.pdf
Security
========
* ssh-agent(1): restrict ssh-agent from signing web challenges for
FIDO/U2F keys.
When signing messages in ssh-agent using a FIDO key that has an
application string that does not start with "ssh:", ensure that the
message being signed is one of the forms expected for the SSH protocol
(currently public key authentication and sshsig signatures).
This prevents ssh-agent forwarding on a host that has FIDO keys
attached granting the ability for the remote side to sign challenges
for web authentication using those keys too.
Note that the converse case of web browsers signing SSH challenges is
already precluded because no web RP can have the "ssh:" prefix in the
application string that we require.
* ssh-keygen(1): Enable FIDO 2.1 credProtect extension when generating
a FIDO resident key.
The recent FIDO 2.1 Client to Authenticator Protocol introduced a
"credProtect" feature to better protect resident keys. We use this
option to require a PIN prior to all operations that may retrieve
a resident key from a FIDO token.
Potentially-incompatible changes
================================
This release includes a number of changes that may affect existing
configurations:
* For FIDO/U2F support, OpenSSH recommends the use of libfido2 1.5.0
or greater. Older libraries have limited support at the expense of
disabling particular features. These include resident keys, PIN-
required keys and multiple attached tokens.
* ssh-keygen(1): the format of the attestation information optionally
recorded when a FIDO key is generated has changed. It now includes
the authenticator data needed to validate attestation signatures.
* The API between OpenSSH and the FIDO token middleware has changed
and the SSH_SK_VERSION_MAJOR version has been incremented as a
result. Third-party middleware libraries must support the current
API version (7) to work with OpenSSH 8.4.
* The portable OpenSSH distribution now requires automake to rebuild
the configure script and supporting files. This is not required when
simply building portable OpenSSH from a release tar file.
Changes since OpenSSH 8.3
=========================
New features
------------
* ssh(1), ssh-keygen(1): support for FIDO keys that require a PIN for
each use. These keys may be generated using ssh-keygen using a new
"verify-required" option. When a PIN-required key is used, the user
will be prompted for a PIN to complete the signature operation.
* sshd(8): authorized_keys now supports a new "verify-required"
option to require FIDO signatures assert that the token verified
that the user was present before making the signature. The FIDO
protocol supports multiple methods for user-verification, but
currently OpenSSH only supports PIN verification.
* sshd(8), ssh-keygen(1): add support for verifying FIDO webauthn
signatures. Webauthn is a standard for using FIDO keys in web
browsers. These signatures are a slightly different format to plain
FIDO signatures and thus require explicit support.
* ssh(1): allow some keywords to expand shell-style ${ENV}
environment variables. The supported keywords are CertificateFile,
ControlPath, IdentityAgent and IdentityFile, plus LocalForward and
RemoteForward when used for Unix domain socket paths. bz#3140
* ssh(1), ssh-agent(1): allow some additional control over the use of
ssh-askpass via a new $SSH_ASKPASS_REQUIRE environment variable,
including forcibly enabling and disabling its use. bz#69
* ssh(1): allow ssh_config(5)'s AddKeysToAgent keyword accept a time
limit for keys in addition to its current flag options. Time-
limited keys will automatically be removed from ssh-agent after
their expiry time has passed.
* scp(1), sftp(1): allow the -A flag to explicitly enable agent
forwarding in scp and sftp. The default remains to not forward an
agent, even when ssh_config enables it.
* ssh(1): add a '%k' TOKEN that expands to the effective HostKey of
the destination. This allows, e.g., keeping host keys in individual
files using "UserKnownHostsFile ~/.ssh/known_hosts.d/%k". bz#1654
* ssh(1): add %-TOKEN, environment variable and tilde expansion to
the UserKnownHostsFile directive, allowing the path to be
completed by the configuration (e.g. bz#1654)
* ssh-keygen(1): allow "ssh-add -d -" to read keys to be deleted
from stdin. bz#3180
* sshd(8): improve logging for MaxStartups connection throttling.
sshd will now log when it starts and stops throttling and periodically
while in this state. bz#3055
Bugfixes
--------
* ssh(1), ssh-keygen(1): better support for multiple attached FIDO
tokens. In cases where OpenSSH cannot unambiguously determine which
token to direct a request to, the user is now required to select a
token by touching it. In cases of operations that require a PIN to
be verified, this avoids sending the wrong PIN to the wrong token
and incrementing the token's PIN failure counter (tokens
effectively erase their keys after too many PIN failures).
* sshd(8): fix Include before Match in sshd_config; bz#3122
* ssh(1): close stdin/out/error when forking after authentication
completes ("ssh -f ...") bz#3137
* ssh(1), sshd(8): limit the amount of channel input data buffered,
avoiding peers that advertise large windows but are slow to read
from causing high memory consumption.
* ssh-agent(1): handle multiple requests sent in a single write() to
the agent.
* sshd(8): allow sshd_config longer than 256k
* sshd(8): avoid spurious "Unable to load host key" message when sshd
load a private key but no public counterpart
* ssh(1): prefer the default hostkey algorithm list whenever we have
a hostkey that matches its best-preference algorithm.
* sshd(1): when ordering the hostkey algorithms to request from a
server, prefer certificate types if the known_hosts files contain a key
marked as a @cert-authority; bz#3157
* ssh(1): perform host key fingerprint comparisons for the "Are you
sure you want to continue connecting (yes/no/[fingerprint])?"
prompt with case sensitivity.
* sshd(8): ensure that address/masklen mismatches in sshd_config
yield fatal errors at daemon start time rather than later when
they are evaluated.
* ssh-keygen(1): ensure that certificate extensions are lexically
sorted. Previously if the user specified a custom extension then
the everything would be in order except the custom ones. bz#3198
* ssh(1): also compare username when checking for JumpHost loops.
bz#3057
* ssh-keygen(1): preserve group/world read permission on known_hosts
files across runs of "ssh-keygen -Rf /path". The old behaviour was
to remove all rights for group/other. bz#3146
* ssh-keygen(1): Mention the [-a rounds] flag in the ssh-keygen
manual page and usage().
* sshd(8): explicitly construct path to ~/.ssh/rc rather than
relying on it being relative to the current directory, so that it
can still be found if the shell startup changes its directory.
bz#3185
* sshd(8): when redirecting sshd's log output to a file, undo this
redirection after the session child process is forked(). Fixes
missing log messages when using this feature under some
circumstances.
* sshd(8): start ClientAliveInterval bookkeeping before first pass
through select() loop; fixed theoretical case where busy sshd may
ignore timeouts from client.
* ssh(1): only reset the ServerAliveInterval check when we receive
traffic from the server and ignore traffic from a port forwarding
client, preventing a client from keeping a connection alive when
it should be terminated. bz#2265
* ssh-keygen(1): avoid spurious error message when ssh-keygen
creates files outside ~/.ssh
* sftp-client(1): fix off-by-one error that caused sftp downloads to
make one more concurrent request that desired. This prevented using
sftp(1) in unpipelined request/response mode, which is useful when
debugging. bz#3054
* ssh(1), sshd(8): handle EINTR in waitfd() and timeout_connect()
helpers. bz#3071
* ssh(1), ssh-keygen(1): defer creation of ~/.ssh until we attempt to
write to it so we don't leave an empty .ssh directory when it's not
needed. bz#3156
* ssh(1), sshd(8): fix multiplier when parsing time specifications
when handling seconds after other units. bz#3171
Portability
-----------
* sshd(8): always send any PAM account messages. If the PAM account
stack returns any messages, always send them to the user and not
just if the check succeeds. bz#2049
* Implement some backwards compatibility for libfido2 libraries
older than 1.5.0. Note that use of an older library will result
in the loss of certain features including resident key support,
PIN support and support for multiple attached tokens.
* configure fixes for XCode 12
* gnome-ssh-askpass3: ensure the "close" button is not focused by
default for SSH_ASKPASS_PROMPT=none prompts. Avoids space/enter
accidentally dismissing FIDO touch notifications.
* gnome-ssh-askpass3: allow some control over textarea colour via
$GNOME_SSH_ASKPASS_FG_COLOR and $GNOME_SSH_ASKPASS_BG_COLOR
environment variables.
* sshd(8): document another PAM spec problem in a frustrated comment
* sshd(8): support NetBSD's utmpx.ut_ss address field. bz#960
* Add the ssh-sk-helper binary and its manpage to the RPM spec file
* Detect the Frankenstein monster of Linux/X32 and allow the sandbox
to function there. bz#3085
Cherry-picked from upstream:
https://git.savannah.gnu.org/gitweb/?p=config.git;a=commit;h=1c4398015583eb77bc043234f5734be055e64bea
Everything except external/apache2/llvm/dist/llvm/cmake/config.guess
is patched, which is under vendor tag and cannot be modified. I expect
that this file is not actually used as we use hand-crafted version of
configure script instead of cmake for building LLVM.
Note that external/apache2/llvm/autoconf/autoconf/config.guess has
already been committed on Oct. 20, but commit message disappeared as
cvs aborted due to "permission denied" when trying to modify the file
mentioned above. Sorry for confusing you.
Also note that GMP uses its own config.guess Patch for
external/lgpl3/gmp/dist/config.guess is provided by ryo@. Thanks!
Fix ssh-keygen(1) on aarch64eb. Also, all tests in tests/crypto pass
with this change.
As martin pointed out when this macro was defined for sparc64,
http://cvsweb.netbsd.org/bsdweb.cgi/src/crypto/external/bsd/openssl/include/openssl/opensslconf.h#rev1.5
this code seems broken on LP64BE architectures.
At the moment, mips64eb is not affected since only N32 is supported as
userland. Also, we do not support powerpc64 (eb) yet. But we may need to
take care of them in future.
Update comment; FPU emulation seems to work just fine now. However,
FPU-optimized code should still be avoided for better performance,
if FPU is not present.
openssl fails on FPU emulation for powerpc
When machdep.fpu_present sysctl variable can be retrieved, and
its value is zero, avoid using FPU arithmetic.
FPU is absent and emulated by kernel in that case, and calculation
results are not correct in bit-to-bit precision.
This behavior should be useful even if we could fix FPU emulation;
it is much faster to skip FPU arithmetic in general, rather than
relying upon emulation by kernel via illegal instruction handler.
instead (dot-asm:
So that both assembly modules export SHA3_absorb_vsx... Either way,
it makes lesser sense to deploy vector keccak1600p8-ppc.pl, because
benefits are not that clear. It's only nominally faster than scalar
module on POWER8 but significantly slower on POWER9. Because POWER9
is better equipped to handle non-vector code. On related note,
there is version optimized for little-endian, as well as 32-bit
version. [And since MIPS was mentioned, there is even MIPS module...]
mirrors listed at https://www.openssh.com/.
OpenSSH is a 100% complete SSH protocol 2.0 implementation and
includes sftp client and server support.
Once again, we would like to thank the OpenSSH community for their
continued support of the project, especially those who contributed
code or patches, reported bugs, tested snapshots or donated to the
project. More information on donations may be found at:
https://www.openssh.com/donations.html
Future deprecation notice
=========================
It is now possible[1] to perform chosen-prefix attacks against the
SHA-1 algorithm for less than USD$50K. For this reason, we will be
disabling the "ssh-rsa" public key signature algorithm by default in a
near-future release.
This algorithm is unfortunately still used widely despite the
existence of better alternatives, being the only remaining public key
signature algorithm specified by the original SSH RFCs.
The better alternatives include:
* The RFC8332 RSA SHA-2 signature algorithms rsa-sha2-256/512. These
algorithms have the advantage of using the same key type as
"ssh-rsa" but use the safe SHA-2 hash algorithms. These have been
supported since OpenSSH 7.2 and are already used by default if the
client and server support them.
* The ssh-ed25519 signature algorithm. It has been supported in
OpenSSH since release 6.5.
* The RFC5656 ECDSA algorithms: ecdsa-sha2-nistp256/384/521. These
have been supported by OpenSSH since release 5.7.
To check whether a server is using the weak ssh-rsa public key
algorithm, for host authentication, try to connect to it after
removing the ssh-rsa algorithm from ssh(1)'s allowed list:
ssh -oHostKeyAlgorithms=-ssh-rsa user@host
If the host key verification fails and no other supported host key
types are available, the server software on that host should be
upgraded.
A future release of OpenSSH will enable UpdateHostKeys by default
to allow the client to automatically migrate to better algorithms.
Users may consider enabling this option manually. Vendors of devices
that implement the SSH protocol should ensure that they support the
new signature algorithms for RSA keys.
[1] "SHA-1 is a Shambles: First Chosen-Prefix Collision on SHA-1 and
Application to the PGP Web of Trust" Leurent, G and Peyrin, T
(2020) https://eprint.iacr.org/2020/014.pdf
Security
========
* scp(1): when receiving files, scp(1) could be become desynchronised
if a utimes(2) system call failed. This could allow file contents
to be interpreted as file metadata and thereby permit an adversary
to craft a file system that, when copied with scp(1) in a
configuration that caused utimes(2) to fail (e.g. under a SELinux
policy or syscall sandbox), transferred different file names and
contents to the actual file system layout.
Exploitation of this is not likely as utimes(2) does not fail under
normal circumstances. Successful exploitation is not silent - the
output of scp(1) would show transfer errors followed by the actual
file(s) that were received.
Finally, filenames returned from the peer are (since openssh-8.0)
matched against the user's requested destination, thereby
disallowing a successful exploit from writing files outside the
user's selected target glob (or directory, in the case of a
recursive transfer). This ensures that this attack can achieve no
more than a hostile peer is already able to achieve within the scp
protocol.
Potentially-incompatible changes
================================
This release includes a number of changes that may affect existing
configurations:
* sftp(1): reject an argument of "-1" in the same way as ssh(1) and
scp(1) do instead of accepting and silently ignoring it.
Changes since OpenSSH 8.2
=========================
The focus of this release is bug fixing.
New Features
------------
* sshd(8): make IgnoreRhosts a tri-state option: "yes" to ignore
rhosts/shosts, "no" allow rhosts/shosts or (new) "shosts-only"
to allow .shosts files but not .rhosts.
* sshd(8): allow the IgnoreRhosts directive to appear anywhere in a
sshd_config, not just before any Match blocks; bz3148
* ssh(1): add %TOKEN percent expansion for the LocalFoward and
RemoteForward keywords when used for Unix domain socket forwarding.
bz#3014
* all: allow loading public keys from the unencrypted envelope of a
private key file if no corresponding public key file is present.
* ssh(1), sshd(8): prefer to use chacha20 from libcrypto where
possible instead of the (slower) portable C implementation included
in OpenSSH.
* ssh-keygen(1): add ability to dump the contents of a binary key
revocation list via "ssh-keygen -lQf /path" bz#3132
Bugfixes
--------
* ssh(1): fix IdentitiesOnly=yes to also apply to keys loaded from
a PKCS11Provider; bz#3141
* ssh-keygen(1): avoid NULL dereference when trying to convert an
invalid RFC4716 private key.
* scp(1): when performing remote-to-remote copies using "scp -3",
start the second ssh(1) channel with BatchMode=yes enabled to
avoid confusing and non-deterministic ordering of prompts.
* ssh(1), ssh-keygen(1): when signing a challenge using a FIDO token,
perform hashing of the message to be signed in the middleware layer
rather than in OpenSSH code. This permits the use of security key
middlewares that perform the hashing implicitly, such as Windows
Hello.
* ssh(1): fix incorrect error message for "too many known hosts
files." bz#3149
* ssh(1): make failures when establishing "Tunnel" forwarding
terminate the connection when ExitOnForwardFailure is enabled;
bz#3116
* ssh-keygen(1): fix printing of fingerprints on private keys and add
a regression test for same.
* sshd(8): document order of checking AuthorizedKeysFile (first) and
AuthorizedKeysCommand (subsequently, if the file doesn't match);
bz#3134
* sshd(8): document that /etc/hosts.equiv and /etc/shosts.equiv are
not considered for HostbasedAuthentication when the target user is
root; bz#3148
* ssh(1), ssh-keygen(1): fix NULL dereference in private certificate
key parsing (oss-fuzz #20074).
* ssh(1), sshd(8): more consistency between sets of %TOKENS are
accepted in various configuration options.
* ssh(1), ssh-keygen(1): improve error messages for some common
PKCS#11 C_Login failure cases; bz#3130
* ssh(1), sshd(8): make error messages for problems during SSH banner
exchange consistent with other SSH transport-layer error messages
and ensure they include the relevant IP addresses bz#3129
* various: fix a number of spelling errors in comments and debug/error
messages
* ssh-keygen(1), ssh-add(1): when downloading FIDO2 resident keys
from a token, don't prompt for a PIN until the token has told us
that it needs one. Avoids double-prompting on devices that
implement on-device authentication.
* sshd(8), ssh-keygen(1): no-touch-required FIDO certificate option
should be an extension, not a critical option.
* ssh(1), ssh-keygen(1), ssh-add(1): offer a better error message
when trying to use a FIDO key function and SecurityKeyProvider is
empty.
* ssh-add(1), ssh-agent(8): ensure that a key lifetime fits within
the values allowed by the wire format (u32). Prevents integer
wraparound of the timeout values. bz#3119
* ssh(1): detect and prevent trivial configuration loops when using
ProxyJump. bz#3057.
Portability
-----------
* Detect systems where signals flagged with SA_RESTART will interrupt
select(2). POSIX permits implementations to choose whether
select(2) will return when interrupted with a SA_RESTART-flagged
signal, but OpenSSH requires interrupting behaviour.
* Several compilation fixes for HP/UX and AIX.
* On platforms that do not support setting process-wide routing
domains (all excepting OpenBSD at present), fail to accept a
configuration attempts to set one at process start time rather than
fatally erroring at run time. bz#3126
* Improve detection of egrep (used in regression tests) on platforms
that offer a poor default one (e.g. Solaris).
* A number of shell portability fixes for the regression tests.
* Fix theoretical infinite loop in the glob(3) replacement
implementation.
* Fix seccomp sandbox compilation problems for some Linux
configurations bz#3085
* Improved detection of libfido2 and some compilation fixes for some
configurations when --with-security-key-builtin is selected.
