*) Avoid loading of a dynamic engine twice.
[Bernd Edlinger]
*) Fixed building on Debian with kfreebsd kernels
[Mattias Ellert]
*) Prioritise DANE TLSA issuer certs over peer certs
[Viktor Dukhovni]
*) Fixed random API for MacOS prior to 10.12
These MacOS versions don't support the CommonCrypto APIs
[Lenny Primak]
Changes between 1.1.1k and 1.1.1l [24 Aug 2021]
*) Fixed an SM2 Decryption Buffer Overflow.
In order to decrypt SM2 encrypted data an application is expected
to call the API function EVP_PKEY_decrypt(). Typically an application
will call this function twice. The first time, on entry, the "out"
parameter can be NULL and, on exit, the "outlen" parameter is
populated with the buffer size required to hold the decrypted
plaintext. The application can then allocate a sufficiently sized
buffer and call EVP_PKEY_decrypt() again, but this time passing
a non-NULL value for the "out" parameter.
A bug in the implementation of the SM2 decryption code means that
the calculation of the buffer size required to hold the plaintext
returned by the first call to EVP_PKEY_decrypt() can be smaller
than the actual size required by the second call. This can lead to
a buffer overflow when EVP_PKEY_decrypt() is called by the application
a second time with a buffer that is too small.
A malicious attacker who is able present SM2 content for decryption
to an application could cause attacker chosen data to overflow the
buffer by up to a maximum of 62 bytes altering the contents of
other data held after the buffer, possibly changing application
behaviour or causing the application to crash. The location of the
buffer is application dependent but is typically heap allocated.
(CVE-2021-3711)
[Matt Caswell]
*) Fixed various read buffer overruns processing ASN.1 strings
ASN.1 strings are represented internally within OpenSSL as an
ASN1_STRING structure which contains a buffer holding the string
data and a field holding the buffer length. This contrasts with
normal C strings which are repesented as a buffer for the string
data which is terminated with a NUL (0) byte.
Although not a strict requirement, ASN.1 strings that are parsed
using OpenSSL's own "d2i" functions (and other similar parsing
functions) as well as any string whose value has been set with the
ASN1_STRING_set() function will additionally NUL terminate the byte
array in the ASN1_STRING structure.
However, it is possible for applications to directly construct
valid ASN1_STRING structures which do not NUL terminate the byte
array by directly setting the "data" and "length" fields in the
ASN1_STRING array. This can also happen by using the ASN1_STRING_set0()
function.
Numerous OpenSSL functions that print ASN.1 data have been found
to assume that the ASN1_STRING byte array will be NUL terminated,
even though this is not guaranteed for strings that have been
directly constructed. Where an application requests an ASN.1
structure to be printed, and where that ASN.1 structure contains
ASN1_STRINGs that have been directly constructed by the application
without NUL terminating the "data" field, then a read buffer overrun
can occur.
The same thing can also occur during name constraints processing
of certificates (for example if a certificate has been directly
constructed by the application instead of loading it via the OpenSSL
parsing functions, and the certificate contains non NUL terminated
ASN1_STRING structures). It can also occur in the X509_get1_email(),
X509_REQ_get1_email() and X509_get1_ocsp() functions.
If a malicious actor can cause an application to directly construct
an ASN1_STRING and then process it through one of the affected
OpenSSL functions then this issue could be hit. This might result
in a crash (causing a Denial of Service attack). It could also
result in the disclosure of private memory contents (such as private
keys, or sensitive plaintext).
(CVE-2021-3712)
[Matt Caswell]
OpenSSH 8.7 has deprecated ChallengeResponseAuthentication, but not removed
it. It is now an alias for KbdInteractiveAuthentication (as are the prior
aliases of ChallengeResponseAuthentication).
I think this chunk was accidentally dropped in the OpenSSH 8.7 merge.
Imminent deprecation notice
===========================
OpenSSH will disable the ssh-rsa signature scheme by default in the
next release.
In the SSH protocol, the "ssh-rsa" signature scheme uses the SHA-1
hash algorithm in conjunction with the RSA public key algorithm.
It is now possible[1] to perform chosen-prefix attacks against the
SHA-1 algorithm for less than USD$50K.
Note that the deactivation of "ssh-rsa" signatures does not necessarily
require cessation of use for RSA keys. In the SSH protocol, keys may be
capable of signing using multiple algorithms. In particular, "ssh-rsa"
keys are capable of signing using "rsa-sha2-256" (RSA/SHA256),
"rsa-sha2-512" (RSA/SHA512) and "ssh-rsa" (RSA/SHA1). Only the last of
these is being turned off by default.
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 that is still
enabled by default.
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 RFC8709 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.
OpenSSH recently enabled the UpdateHostKeys option by default to
assist the client by automatically migrating to better algorithms.
[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
Potentially-incompatible changes
================================
This release includes a number of changes that may affect existing
configurations:
* scp(1): this release changes the behaviour of remote to remote
copies (e.g. "scp host-a:/path host-b:") to transfer through the
local host by default. This was previously available via the -3
flag. This mode avoids the need to expose credentials on the
origin hop, avoids triplicate interpretation of filenames by the
shell (by the local system, the copy origin and the destination)
and, in conjunction with the SFTP support for scp(1) mentioned
below, allows use of all authentication methods to the remote
hosts (previously, only non-interactive methods could be used).
A -R flag has been added to select the old behaviour.
* ssh(1)/sshd(8): both the client and server are now using a
stricter configuration file parser. The new parser uses more
shell-like rules for quotes, space and escape characters. It is
also more strict in rejecting configurations that include options
lacking arguments. Previously some options (e.g. DenyUsers) could
appear on a line with no subsequent arguments. This release will
reject such configurations. The new parser will also reject
configurations with unterminated quotes and multiple '='
characters after the option name.
* ssh(1): when using SSHFP DNS records for host key verification,
ssh(1) will verify all matching records instead of just those
with the specific signature type requested. This may cause host
key verification problems if stale SSHFP records of a different
or legacy signature type exist alongside other records for a
particular host. bz#3322
* ssh-keygen(1): when generating a FIDO key and specifying an
explicit attestation challenge (using -Ochallenge), the challenge
will now be hashed by the builtin security key middleware. This
removes the (undocumented) requirement that challenges be exactly
32 bytes in length and matches the expectations of libfido2.
* sshd(8): environment="..." directives in authorized_keys files are
now first-match-wins and limited to 1024 discrete environment
variable names.
Changes since OpenSSH 8.6
=========================
This release contains a mix of new features and bug-fixes.
New features
------------
- scp(1): experimental support for transfers using the SFTP protocol
as a replacement for the venerable SCP/RCP protocol that it has
traditionally used. SFTP offers more predictable filename handling
and does not require expansion of glob(3) patterns via the shell
on the remote side.
SFTP support may be enabled via a temporary scp -s flag. It is
intended for SFTP to become the default transfer mode in the
near future, at which time the -s flag will be removed. The -O
flag exists to force use of the original SCP/RCP protocol for
cases where SFTP may be unavailable or incompatible.
- sftp-server(8): add a protocol extension to support expansion of
~/ and ~user/ prefixed paths. This was added to support these
paths when used by scp(1) while in SFTP mode.
- ssh(1): add a ForkAfterAuthentication ssh_config(5) counterpart to
the ssh(1) -f flag. GHPR#231
- ssh(1): add a StdinNull directive to ssh_config(5) that allows the
config file to do the same thing as -n does on the ssh(1) command-
line. GHPR#231
- ssh(1): add a SessionType directive to ssh_config, allowing the
configuration file to offer equivalent control to the -N (no
session) and -s (subsystem) command-line flags. GHPR#231
- ssh-keygen(1): allowed signers files used by ssh-keygen(1)
signatures now support listing key validity intervals alongside
they key, and ssh-keygen(1) can optionally check during signature
verification whether a specified time falls inside this interval.
This feature is intended for use by git to support signing and
verifying objects using ssh keys.
- ssh-keygen(8): support printing of the full public key in a sshsig
signature via a -Oprint-pubkey flag.
Bugfixes
--------
* ssh(1)/sshd(8): start time-based re-keying exactly on schedule in
the client and server mainloops. Previously the re-key timeout
could expire but re-keying would not start until a packet was sent
or received, causing a spin in select() if the connection was
quiescent.
* ssh-keygen(1): avoid Y2038 problem in printing certificate
validity lifetimes. Dates past 2^31-1 seconds since epoch were
displayed incorrectly on some platforms. bz#3329
* scp(1): allow spaces to appear in usernames for local to remote
and scp -3 remote to remote copies. bz#1164
* ssh(1)/sshd(8): remove references to ChallengeResponseAuthentication
in favour of KbdInteractiveAuthentication. The former is what was in
SSHv1, the latter is what is in SSHv2 (RFC4256) and they were
treated as somewhat but not entirely equivalent. We retain the old
name as a deprecated alias so configuration files continue to work
as well as a reference in the man page for people looking for it.
bz#3303
* ssh(1)/ssh-add(1)/ssh-keygen(1): fix decoding of X.509 subject name
when extracting a key from a PKCS#11 certificate. bz#3327
* ssh(1): restore blocking status on stdio fds before close. ssh(1)
needs file descriptors in non-blocking mode to operate but it was
not restoring the original state on exit. This could cause
problems with fds shared with other programs via the shell,
bz#3280 and GHPR#246
* ssh(1)/sshd(8): switch both client and server mainloops from
select(3) to pselect(3). Avoids race conditions where a signal
may arrive immediately before select(3) and not be processed until
an event fires. bz#2158
* ssh(1): sessions started with ControlPersist were incorrectly
executing a shell when the -N (no shell) option was specified.
bz#3290
* ssh(1): check if IPQoS or TunnelDevice are already set before
overriding. Prevents values in config files from overriding values
supplied on the command line. bz#3319
* ssh(1): fix debug message when finding a private key to match a
certificate being attempted for user authentication. Previously it
would print the certificate's path, whereas it was supposed to be
showing the private key's path. GHPR#247
* sshd(8): match host certificates against host public keys, not
private keys. Allows use of certificates with private keys held in
a ssh-agent. bz#3524
* ssh(1): add a workaround for a bug in OpenSSH 7.4 sshd(8), which
allows RSA/SHA2 signatures for public key authentication but fails
to advertise this correctly via SSH2_MSG_EXT_INFO. This causes
clients of these server to incorrectly match
PubkeyAcceptedAlgorithmse and potentially refuse to offer valid
keys. bz#3213
* sftp(1)/scp(1): degrade gracefully if a sftp-server offers the
limits@openssh.com extension but fails when the client tries to
invoke it. bz#3318
* ssh(1): allow ssh_config SetEnv to override $TERM, which is
otherwise handled specially by the protocol. Useful in ~/.ssh/config
to set TERM to something generic (e.g. "xterm" instead of
"xterm-256color") for destinations that lack terminfo entries.
* sftp-server(8): the limits@openssh.com extension was incorrectly
marked as an operation that writes to the filesystem, which made it
unavailable in sftp-server read-only mode. bz#3318
* ssh(1): fix SEGV in UpdateHostkeys debug() message, triggered when
the update removed more host keys than remain present.
* many manual page fixes.
Portability
-----------
* ssh(1): move closefrom() to before first malloc. When built against
tcmalloc, the closefrom() would stomp on file descriptors created
for tcmalloc's internal use. bz#3321
* sshd(8): handle GIDs > 2^31 in getgrouplist. When compiled in 32bit
mode, the getgrouplist implementation may fail for GIDs greater than
LONG_MAX.
* ssh(1): xstrdup environment variable used by ForwardAgent. bz#3328
* sshd(8): don't sigdie() in signal handler in privsep child process;
this can end up causing sandbox violations per bz3286
The conversion from 'unsigned long' to 'int' in line 805 is due to the
laziness of declaring a carry flag as BN_ULONG, to save an extra
line of declaration.
The constants in conditional context come from the macro 'bn_cp_32'.
The unconst cast is used for initializing local BIGNUM constants; the
struct member is declared as non-const pointer.
The type widths are handled carefully, so even if there is some
conversion from 64-bit long to uint32_t, no value bits get lost.
The fallthrough case statements are a variant of Duff's Device.
The bitwise '>>' on signed value is actually on a value of type
'unsigned char', and since all platforms supported by lint have
sizeof(int) == 4, the behavior is well defined.
Fixed a problem with verifying a certificate chain when using the
X509_V_FLAG_X509_STRICT flag. This flag enables additional security
checks of the certificates present in a certificate chain. It is
not set by default.
Starting from OpenSSL version 1.1.1h a check to disallow certificates
in the chain that have explicitly encoded elliptic curve parameters
was added as an additional strict check.
An error in the implementation of this check meant that the result
of a previous check to confirm that certificates in the chain are
valid CA certificates was overwritten. This effectively bypasses
the check that non-CA certificates must not be able to issue other
certificates.
If a "purpose" has been configured then there is a subsequent
opportunity for checks that the certificate is a valid CA. All of
the named "purpose" values implemented in libcrypto perform this
check. Therefore, where a purpose is set the certificate chain will
still be rejected even when the strict flag has been used. A purpose
is set by default in libssl client and server certificate verification
routines, but it can be overridden or removed by an application.
In order to be affected, an application must explicitly set the
X509_V_FLAG_X509_STRICT verification flag and either not set a
purpose for the certificate verification or, in the case of TLS
client or server applications, override the default purpose.
([CVE-2021-3450])
Tomasz Mraz
Fixed an issue where an OpenSSL TLS server may crash if sent a
maliciously crafted renegotiation ClientHello message from a client.
If a TLSv1.2 renegotiation ClientHello omits the signature_algorithms
extension (where it was present in the initial ClientHello), but
includes a signature_algorithms_cert extension then a NULL pointer
dereference will result, leading to a crash and a denial of service
attack.
A server is only vulnerable if it has TLSv1.2 and renegotiation
enabled (which is the default configuration). OpenSSL TLS clients
are not impacted by this issue. ([CVE-2021-3449])
Peter Kaestle and Samuel Sapalski
OpenSSH 8.5 was released on 2021-03-03. It is available from the
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.
In the SSH protocol, the "ssh-rsa" signature scheme uses the SHA-1
hash algorithm in conjunction with the RSA public key algorithm.
OpenSSH will disable this signature scheme by default in the near
future.
Note that the deactivation of "ssh-rsa" signatures does not necessarily
require cessation of use for RSA keys. In the SSH protocol, keys may be
capable of signing using multiple algorithms. In particular, "ssh-rsa"
keys are capable of signing using "rsa-sha2-256" (RSA/SHA256),
"rsa-sha2-512" (RSA/SHA512) and "ssh-rsa" (RSA/SHA1). Only the last of
these is being turned off by default.
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 that is still
enabled by default.
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 RFC8709 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.
This release enables the UpdateHostKeys option by default to assist
the client by automatically migrating to better algorithms.
[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): fixed a double-free memory corruption that was
introduced in OpenSSH 8.2 . We treat all such memory faults as
potentially exploitable. This bug could be reached by an attacker
with access to the agent socket.
On modern operating systems where the OS can provide information
about the user identity connected to a socket, OpenSSH ssh-agent
and sshd limit agent socket access only to the originating user
and root. Additional mitigation may be afforded by the system's
malloc(3)/free(3) implementation, if it detects double-free
conditions.
The most likely scenario for exploitation is a user forwarding an
agent either to an account shared with a malicious user or to a
host with an attacker holding root access.
* Portable sshd(8): Prevent excessively long username going to PAM.
This is a mitigation for a buffer overflow in Solaris' PAM username
handling (CVE-2020-14871), and is only enabled for Sun-derived PAM
implementations. This is not a problem in sshd itself, it only
prevents sshd from being used as a vector to attack Solaris' PAM.
It does not prevent the bug in PAM from being exploited via some
other PAM application. GHPR212
Potentially-incompatible changes
================================
This release includes a number of changes that may affect existing
configurations:
* ssh(1), sshd(8): this release changes the first-preference signature
algorithm from ECDSA to ED25519.
* ssh(1), sshd(8): set the TOS/DSCP specified in the configuration
for interactive use prior to TCP connect. The connection phase of
the SSH session is time-sensitive and often explicitly interactive.
The ultimate interactive/bulk TOS/DSCP will be set after
authentication completes.
* ssh(1), sshd(8): remove the pre-standardization cipher
rijndael-cbc@lysator.liu.se. It is an alias for aes256-cbc before
it was standardized in RFC4253 (2006), has been deprecated and
disabled by default since OpenSSH 7.2 (2016) and was only briefly
documented in ssh.1 in 2001.
* ssh(1), sshd(8): update/replace the experimental post-quantum
hybrid key exchange method based on Streamlined NTRU Prime coupled
with X25519.
The previous sntrup4591761x25519-sha512@tinyssh.org method is
replaced with sntrup761x25519-sha512@openssh.com. Per its
designers, the sntrup4591761 algorithm was superseded almost two
years ago by sntrup761.
(note this both the updated method and the one that it replaced are
disabled by default)
* ssh(1): disable CheckHostIP by default. It provides insignificant
benefits while making key rotation significantly more difficult,
especially for hosts behind IP-based load-balancers.
Changes since OpenSSH 8.4
=========================
New features
------------
* ssh(1): this release enables UpdateHostkeys by default subject to
some conservative preconditions:
- The key was matched in the UserKnownHostsFile (and not in the
GlobalKnownHostsFile).
- The same key does not exist under another name.
- A certificate host key is not in use.
- known_hosts contains no matching wildcard hostname pattern.
- VerifyHostKeyDNS is not enabled.
- The default UserKnownHostsFile is in use.
We expect some of these conditions will be modified or relaxed in
future.
* ssh(1), sshd(8): add a new LogVerbose configuration directive for
that allows forcing maximum debug logging by file/function/line
pattern-lists.
* ssh(1): when prompting the user to accept a new hostkey, display
any other host names/addresses already associated with the key.
* ssh(1): allow UserKnownHostsFile=none to indicate that no
known_hosts file should be used to identify host keys.
* ssh(1): add a ssh_config KnownHostsCommand option that allows the
client to obtain known_hosts data from a command in addition to
the usual files.
* ssh(1): add a ssh_config PermitRemoteOpen option that allows the
client to restrict the destination when RemoteForward is used
with SOCKS.
* ssh(1): for FIDO keys, if a signature operation fails with a
"incorrect PIN" reason and no PIN was initially requested from the
user, then request a PIN and retry the operation. This supports
some biometric devices that fall back to requiring PIN when reading
of the biometric failed, and devices that require PINs for all
hosted credentials.
* sshd(8): implement client address-based rate-limiting via new
sshd_config(5) PerSourceMaxStartups and PerSourceNetBlockSize
directives that provide more fine-grained control on a per-origin
address basis than the global MaxStartups limit.
Bugfixes
--------
* ssh(1): Prefix keyboard interactive prompts with "(user@host)" to
make it easier to determine which connection they are associated
with in cases like scp -3, ProxyJump, etc. bz#3224
* sshd(8): fix sshd_config SetEnv directives located inside Match
blocks. GHPR201
* ssh(1): when requesting a FIDO token touch on stderr, inform the
user once the touch has been recorded.
* ssh(1): prevent integer overflow when ridiculously large
ConnectTimeout values are specified, capping the effective value
(for most platforms) at 24 days. bz#3229
* ssh(1): consider the ECDSA key subtype when ordering host key
algorithms in the client.
* ssh(1), sshd(8): rename the PubkeyAcceptedKeyTypes keyword to
PubkeyAcceptedAlgorithms. The previous name incorrectly suggested
that it control allowed key algorithms, when this option actually
specifies the signature algorithms that are accepted. The previous
name remains available as an alias. bz#3253
* ssh(1), sshd(8): similarly, rename HostbasedKeyTypes (ssh) and
HostbasedAcceptedKeyTypes (sshd) to HostbasedAcceptedAlgorithms.
* sftp-server(8): add missing lsetstat@openssh.com documentation
and advertisement in the server's SSH2_FXP_VERSION hello packet.
* ssh(1), sshd(8): more strictly enforce KEX state-machine by
banning packet types once they are received. Fixes memleak caused
by duplicate SSH2_MSG_KEX_DH_GEX_REQUEST (oss-fuzz #30078).
* sftp(1): allow the full range of UIDs/GIDs for chown/chgrp on 32bit
platforms instead of being limited by LONG_MAX. bz#3206
* Minor man page fixes (capitalization, commas, etc.) bz#3223
* sftp(1): when doing an sftp recursive upload or download of a
read-only directory, ensure that the directory is created with
write and execute permissions in the interim so that the transfer
can actually complete, then set the directory permission as the
final step. bz#3222
* ssh-keygen(1): document the -Z, check the validity of its argument
earlier and provide a better error message if it's not correct.
bz#2879
* ssh(1): ignore comments at the end of config lines in ssh_config,
similar to what we already do for sshd_config. bz#2320
* sshd_config(5): mention that DisableForwarding is valid in a
sshd_config Match block. bz3239
* sftp(1): fix incorrect sorting of "ls -ltr" under some
circumstances. bz3248.
* ssh(1), sshd(8): fix potential integer truncation of (unlikely)
timeout values. bz#3250
* ssh(1): make hostbased authentication send the signature algorithm
in its SSH2_MSG_USERAUTH_REQUEST packets instead of the key type.
This make HostbasedAcceptedAlgorithms do what it is supposed to -
filter on signature algorithm and not key type.
Portability
-----------
* sshd(8): add a number of platform-specific syscalls to the Linux
seccomp-bpf sandbox. bz#3232 bz#3260
* sshd(8): remove debug message from sigchld handler that could cause
deadlock on some platforms. bz#3259
* Sync contrib/ssh-copy-id with upstream.
* unittests: add a hostname function for systems that don't have it.
Some systems don't have a hostname command (it's not required by
POSIX). The do have uname -n (which is), but not all of those have
it report the FQDN.
Checksums:
==========
- SHA1 (openssh-8.5.tar.gz) = 04cae43c389fb411227c01219e4eb46e3113f34e
- SHA256 (openssh-8.5.tar.gz) = 5qB2CgzNG4io4DmChTjHgCWqRWvEOvCKJskLdJCz+SU=
- SHA1 (openssh-8.5p1.tar.gz) = 72eadcbe313b07b1dd3b693e41d3cd56d354e24e
- SHA256 (openssh-8.5p1.tar.gz) = 9S8/QdQpqpkY44zyAK8iXM3Y5m8FLaVyhwyJc3ZG7CU=
Please note that the SHA256 signatures are base64 encoded and not
hexadecimal (which is the default for most checksum tools). The PGP
key used to sign the releases is available from the mirror sites:
https://cdn.openbsd.org/pub/OpenBSD/OpenSSH/RELEASE_KEY.asc
Please note that the OpenPGP key used to sign releases has been
rotated for this release. The new key has been signed by the previous
key to provide continuity.
Reporting Bugs:
===============
- Please read https://www.openssh.com/report.html
Security bugs should be reported directly to openssh@openssh.com
*) Fixed the X509_issuer_and_serial_hash() function. It attempts
to create a unique hash value based on the issuer and serial
number data contained within an X509 certificate. However it
was failing to correctly handle any errors that may occur
while parsing the issuer field (which might occur if the issuer
field is maliciously constructed). This may subsequently result
in a NULL pointer deref and a crash leading to a potential
denial of service attack.
(CVE-2021-23841)
[Matt Caswell]
*) Fixed the RSA_padding_check_SSLv23() function and the
RSA_SSLV23_PADDING padding mode to correctly check for rollback
attacks. This is considered a bug in OpenSSL 1.1.1 because it
does not support SSLv2. In 1.0.2 this is CVE-2021-23839.
[Matt Caswell]
*) Fixed the EVP_CipherUpdate, EVP_EncryptUpdate and EVP_DecryptUpdate
functions. Previously they could overflow the output length
argument in some cases where the input length is close to the
maximum permissable length for an integer on the platform. In
such cases the return value from the function call would be
1 (indicating success), but the output length value would be
negative. This could cause applications to behave incorrectly
or crash.
(CVE-2021-23840)
[Matt Caswell]
*) Fixed SRP_Calc_client_key so that it runs in constant time.
The previous implementation called BN_mod_exp without setting
BN_FLG_CONSTTIME. This could be exploited in a side channel
attack to recover the password. Since the attack is local host
only this is outside of the current OpenSSL threat model and
therefore no CVE is assigned.
Thanks to Mohammed Sabt and Daniel De Almeida Braga for reporting
this issue.
[Matt Caswell]
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.
Update netpgpverify and libnetpgpverify to version 20200503
ensure all exported functions use a unique prfix, so that they don't
conflict with symbols (both data and text) in libcrypto. this works for
statically linked binaries and libraries, rather then the version map which
only works for dynalically-linked.
exported. In particular the following symbols:
DSA_SIG_free
DSA_SIG_new
DSA_do_sign
DSA_do_verify
DSA_free
DSA_new
DSA_size
RSA_check_key
RSA_free
RSA_generate_key
RSA_new
RSA_private_decrypt
RSA_private_encrypt
RSA_public_decrypt
RSA_public_encrypt
conflict with libcrypto and break pkg_add which links against both
libraries.
Firstly, include the correct headers. Then, make sure that requests
never exceed 256 bytes.
Disable a hack for old FreeBSD versions, just in case it actually gets
used.
This should mean that OpenSSL doesn't ever fall back to reading from
/dev/urandom.
XXX pullup, XXX upstream.
*) Fixed segmentation fault in SSL_check_chain()
Server or client applications that call the SSL_check_chain() function
during or after a TLS 1.3 handshake may crash due to a NULL pointer
dereference as a result of incorrect handling of the
"signature_algorithms_cert" TLS extension. The crash occurs if an invalid
or unrecognised signature algorithm is received from the peer. This could
be exploited by a malicious peer in a Denial of Service attack.
(CVE-2020-1967)
[Benjamin Kaduk]
*) Added AES consttime code for no-asm configurations
an optional constant time support for AES was added
when building openssl for no-asm.
Enable with: ./config no-asm -DOPENSSL_AES_CONST_TIME
Disable with: ./config no-asm -DOPENSSL_NO_AES_CONST_TIME
At this time this feature is by default disabled.
It will be enabled by default in 3.0.
[Bernd Edlinger]
*) Revert the change of EOF detection while reading in libssl to avoid
regressions in applications depending on the current way of reporting
the EOF. As the existing method is not fully accurate the change to
reporting the EOF via SSL_ERROR_SSL is kept on the current development
branch and will be present in the 3.0 release.
[Tomas Mraz]
*) Revised BN_generate_prime_ex to not avoid factors 3..17863 in p-1
when primes for RSA keys are computed.
Since we previously always generated primes == 2 (mod 3) for RSA keys,
the 2-prime and 3-prime RSA modules were easy to distinguish, since
N = p*q = 1 (mod 3), but N = p*q*r = 2 (mod 3). Therefore fingerprinting
2-prime vs. 3-prime RSA keys was possible by computing N mod 3.
This avoids possible fingerprinting of newly generated RSA modules.
[Bernd Edlinger]
*) Properly detect EOF while reading in libssl. Previously if we hit an EOF
while reading in libssl then we would report an error back to the
application (SSL_ERROR_SYSCALL) but errno would be 0. We now add
an error to the stack (which means we instead return SSL_ERROR_SSL) and
therefore give a hint as to what went wrong.
[Matt Caswell]
*) Check that ed25519 and ed448 are allowed by the security level. Previously
signature algorithms not using an MD were not being checked that they were
allowed by the security level.
[Kurt Roeckx]
*) Fixed SSL_get_servername() behaviour. The behaviour of SSL_get_servername()
was not quite right. The behaviour was not consistent between resumption
and normal handshakes, and also not quite consistent with historical
behaviour. The behaviour in various scenarios has been clarified and
it has been updated to make it match historical behaviour as closely as
possible.
[Matt Caswell]
*) [VMS only] The header files that the VMS compilers include automatically,
__DECC_INCLUDE_PROLOGUE.H and __DECC_INCLUDE_EPILOGUE.H, use pragmas that
the C++ compiler doesn't understand. This is a shortcoming in the
compiler, but can be worked around with __cplusplus guards.
C++ applications that use OpenSSL libraries must be compiled using the
qualifier '/NAMES=(AS_IS,SHORTENED)' to be able to use all the OpenSSL
functions. Otherwise, only functions with symbols of less than 31
characters can be used, as the linker will not be able to successfully
resolve symbols with longer names.
[Richard Levitte]
*) Corrected the documentation of the return values from the EVP_DigestSign*
set of functions. The documentation mentioned negative values for some
errors, but this was never the case, so the mention of negative values
was removed.
Code that followed the documentation and thereby check with something
like 'EVP_DigestSignInit(...) <= 0' will continue to work undisturbed.
[Richard Levitte]
*) Fixed an an overflow bug in the x64_64 Montgomery squaring procedure
used in exponentiation with 512-bit moduli. No EC algorithms are
affected. Analysis suggests that attacks against 2-prime RSA1024,
3-prime RSA1536, and DSA1024 as a result of this defect would be very
difficult to perform and are not believed likely. Attacks against DH512
are considered just feasible. However, for an attack the target would
have to re-use the DH512 private key, which is not recommended anyway.
Also applications directly using the low level API BN_mod_exp may be
affected if they use BN_FLG_CONSTTIME.
(CVE-2019-1551)
[Andy Polyakov]
*) Added a new method to gather entropy on VMS, based on SYS$GET_ENTROPY.
The presence of this system service is determined at run-time.
[Richard Levitte]
*) Added newline escaping functionality to a filename when using openssl dgst.
This output format is to replicate the output format found in the '*sum'
checksum programs. This aims to preserve backward compatibility.
[Matt Eaton, Richard Levitte, and Paul Dale]
*) Print all values for a PKCS#12 attribute with 'openssl pkcs12', not just
the first value.
[Jon Spillett]
- Add GSSAPIAuthentication and related options
- Add KerberosAuthentication and related options
- Bring in the lengthy but useful comment block about
the side-effect of UsePAM with regards to PermitRootLogin.
- Match the case of the UsePAM keyword used in the manual page and code,
to aid case-sensitive grep etc.
- Remove references to obsole UseLogin and UsePrivilegeSeparation keywords.
- Whitespace police
The first matching entry that sets an option "wins." Therefore more
specific matches should be provided before the "Host *" entry that
matches everything. This way options set in the more specific entry will
not be accidentally made ineffective by the match-all entry.
OpenSSH 8.2 was released on 2020-02-14. It is available from the
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 hash algorithm for less than USD$50K. For this reason, we will
be disabling the "ssh-rsa" public key signature algorithm that depends
on SHA-1 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.
[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(1), sshd(8), ssh-keygen(1): this release removes the "ssh-rsa"
(RSA/SHA1) algorithm from those accepted for certificate signatures
(i.e. the client and server CASignatureAlgorithms option) and will
use the rsa-sha2-512 signature algorithm by default when the
ssh-keygen(1) CA signs new certificates.
Certificates are at special risk to the aforementioned SHA1
collision vulnerability as an attacker has effectively unlimited
time in which to craft a collision that yields them a valid
certificate, far more than the relatively brief LoginGraceTime
window that they have to forge a host key signature.
The OpenSSH certificate format includes a CA-specified (typically
random) nonce value near the start of the certificate that should
make exploitation of chosen-prefix collisions in this context
challenging, as the attacker does not have full control over the
prefix that actually gets signed. Nonetheless, SHA1 is now a
demonstrably broken algorithm and futher improvements in attacks
are highly likely.
OpenSSH releases prior to 7.2 do not support the newer RSA/SHA2
algorithms and will refuse to accept certificates signed by an
OpenSSH 8.2+ CA using RSA keys unless the unsafe algorithm is
explicitly selected during signing ("ssh-keygen -t ssh-rsa").
Older clients/servers may use another CA key type such as
ssh-ed25519 (supported since OpenSSH 6.5) or one of the
ecdsa-sha2-nistp256/384/521 types (supported since OpenSSH 5.7)
instead if they cannot be upgraded.
Potentially-incompatible changes
================================
This release includes a number of changes that may affect existing
configurations:
* ssh(1), sshd(8): the above removal of "ssh-rsa" from the accepted
CASignatureAlgorithms list.
* ssh(1), sshd(8): this release removes diffie-hellman-group14-sha1
from the default key exchange proposal for both the client and
server.
* ssh-keygen(1): the command-line options related to the generation
and screening of safe prime numbers used by the
diffie-hellman-group-exchange-* key exchange algorithms have
changed. Most options have been folded under the -O flag.
* sshd(8): the sshd listener process title visible to ps(1) has
changed to include information about the number of connections that
are currently attempting authentication and the limits configured
by MaxStartups.
* ssh-sk-helper(8): this is a new binary. It is used by the FIDO/U2F
support to provide address-space isolation for token middleware
libraries (including the internal one). It needs to be installed
in the expected path, typically under /usr/libexec or similar.
Changes since OpenSSH 8.1
=========================
This release contains some significant new features.
FIDO/U2F Support
----------------
This release adds support for FIDO/U2F hardware authenticators to
OpenSSH. U2F/FIDO are open standards for inexpensive two-factor
authentication hardware that are widely used for website
authentication. In OpenSSH FIDO devices are supported by new public
key types "ecdsa-sk" and "ed25519-sk", along with corresponding
certificate types.
ssh-keygen(1) may be used to generate a FIDO token-backed key, after
which they may be used much like any other key type supported by
OpenSSH, so long as the hardware token is attached when the keys are
used. FIDO tokens also generally require the user explicitly authorise
operations by touching or tapping them.
Generating a FIDO key requires the token be attached, and will usually
require the user tap the token to confirm the operation:
$ ssh-keygen -t ecdsa-sk -f ~/.ssh/id_ecdsa_sk
Generating public/private ecdsa-sk key pair.
You may need to touch your security key to authorize key generation.
Enter file in which to save the key (/home/djm/.ssh/id_ecdsa_sk):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/djm/.ssh/id_ecdsa_sk
Your public key has been saved in /home/djm/.ssh/id_ecdsa_sk.pub
This will yield a public and private key-pair. The private key file
should be useless to an attacker who does not have access to the
physical token. After generation, this key may be used like any other
supported key in OpenSSH and may be listed in authorized_keys, added
to ssh-agent(1), etc. The only additional stipulation is that the FIDO
token that the key belongs to must be attached when the key is used.
FIDO tokens are most commonly connected via USB but may be attached
via other means such as Bluetooth or NFC. In OpenSSH, communication
with the token is managed via a middleware library, specified by the
SecurityKeyProvider directive in ssh/sshd_config(5) or the
$SSH_SK_PROVIDER environment variable for ssh-keygen(1) and
ssh-add(1). The API for this middleware is documented in the sk-api.h
and PROTOCOL.u2f files in the source distribution.
OpenSSH includes a middleware ("SecurityKeyProvider=internal") with
support for USB tokens. It is automatically enabled in OpenBSD and may
be enabled in portable OpenSSH via the configure flag
--with-security-key-builtin. If the internal middleware is enabled
then it is automatically used by default. This internal middleware
requires that libfido2 (https://github.com/Yubico/libfido2) and its
dependencies be installed. We recommend that packagers of portable
OpenSSH enable the built-in middleware, as it provides the
lowest-friction experience for users.
Note: FIDO/U2F tokens are required to implement the ECDSA-P256
"ecdsa-sk" key type, but hardware support for Ed25519 "ed25519-sk" is
less common. Similarly, not all hardware tokens support some of the
optional features such as resident keys.
The protocol-level changes to support FIDO/U2F keys in SSH are
documented in the PROTOCOL.u2f file in the OpenSSH source
distribution.
There are a number of supporting changes to this feature:
* ssh-keygen(1): add a "no-touch-required" option when generating
FIDO-hosted keys, that disables their default behaviour of
requiring a physical touch/tap on the token during authentication.
Note: not all tokens support disabling the touch requirement.
* sshd(8): add a sshd_config PubkeyAuthOptions directive that
collects miscellaneous public key authentication-related options
for sshd(8). At present it supports only a single option
"no-touch-required". This causes sshd to skip its default check for
FIDO/U2F keys that the signature was authorised by a touch or press
event on the token hardware.
* ssh(1), sshd(8), ssh-keygen(1): add a "no-touch-required" option
for authorized_keys and a similar extension for certificates. This
option disables the default requirement that FIDO key signatures
attest that the user touched their key to authorize them, mirroring
the similar PubkeyAuthOptions sshd_config option.
* ssh-keygen(1): add support for the writing the FIDO attestation
information that is returned when new keys are generated via the
"-O write-attestation=/path" option. FIDO attestation certificates
may be used to verify that a FIDO key is hosted in trusted
hardware. OpenSSH does not currently make use of this information,
beyond optionally writing it to disk.
FIDO2 resident keys
-------------------
FIDO/U2F OpenSSH keys consist of two parts: a "key handle" part stored
in the private key file on disk, and a per-device private key that is
unique to each FIDO/U2F token and that cannot be exported from the
token hardware. These are combined by the hardware at authentication
time to derive the real key that is used to sign authentication
challenges.
For tokens that are required to move between computers, it can be
cumbersome to have to move the private key file first. To avoid this
requirement, tokens implementing the newer FIDO2 standard support
"resident keys", where it is possible to effectively retrieve the key
handle part of the key from the hardware.
OpenSSH supports this feature, allowing resident keys to be generated
using the ssh-keygen(1) "-O resident" flag. This will produce a
public/private key pair as usual, but it will be possible to retrieve
the private key part from the token later. This may be done using
"ssh-keygen -K", which will download all available resident keys from
the tokens attached to the host and write public/private key files
for them. It is also possible to download and add resident keys
directly to ssh-agent(1) without writing files to the file-system
using "ssh-add -K".
Resident keys are indexed on the token by the application string and
user ID. By default, OpenSSH uses an application string of "ssh:" and
an empty user ID. If multiple resident keys on a single token are
desired then it may be necessary to override one or both of these
defaults using the ssh-keygen(1) "-O application=" or "-O user="
options. Note: OpenSSH will only download and use resident keys whose
application string begins with "ssh:"
Storing both parts of a key on a FIDO token increases the likelihood
of an attacker being able to use a stolen token device. For this
reason, tokens should enforce PIN authentication before allowing
download of keys, and users should set a PIN on their tokens before
creating any resident keys.
Other New Features
------------------
* sshd(8): add an Include sshd_config keyword that allows including
additional configuration files via glob(3) patterns. bz2468
* ssh(1)/sshd(8): make the LE (low effort) DSCP code point available
via the IPQoS directive; bz2986,
* ssh(1): when AddKeysToAgent=yes is set and the key contains no
comment, add the key to the agent with the key's path as the
comment. bz2564
* ssh-keygen(1), ssh-agent(1): expose PKCS#11 key labels and X.509
subjects as key comments, rather than simply listing the PKCS#11
provider library path. PR138
* ssh-keygen(1): allow PEM export of DSA and ECDSA keys; bz3091
* ssh(1), sshd(8): make zlib compile-time optional, available via the
Makefile.inc ZLIB flag on OpenBSD or via the --with-zlib configure
option for OpenSSH portable.
* sshd(8): when clients get denied by MaxStartups, send a
notification prior to the SSH2 protocol banner according to
RFC4253 section 4.2.
* ssh(1), ssh-agent(1): when invoking the $SSH_ASKPASS prompt
program, pass a hint to the program to describe the type of
desired prompt. The possible values are "confirm" (indicating
that a yes/no confirmation dialog with no text entry should be
shown), "none" (to indicate an informational message only), or
blank for the original ssh-askpass behaviour of requesting a
password/phrase.
* ssh(1): allow forwarding a different agent socket to the path
specified by $SSH_AUTH_SOCK, by extending the existing ForwardAgent
option to accepting an explicit path or the name of an environment
variable in addition to yes/no.
* ssh-keygen(1): add a new signature operations "find-principals" to
look up the principal associated with a signature from an allowed-
signers file.
* sshd(8): expose the number of currently-authenticating connections
along with the MaxStartups limit in the process title visible to
"ps".
Bugfixes
--------
* sshd(8): make ClientAliveCountMax=0 have sensible semantics: it
will now disable connection killing entirely rather than the
current behaviour of instantly killing the connection after the
first liveness test regardless of success. bz2627
* sshd(8): clarify order of AllowUsers / DenyUsers vs AllowGroups /
DenyGroups in the sshd(8) manual page. bz1690
* sshd(8): better describe HashKnownHosts in the manual page. bz2560
* sshd(8): clarify that that permitopen=/PermitOpen do no name or
address translation in the manual page. bz3099
* sshd(8): allow the UpdateHostKeys feature to function when
multiple known_hosts files are in use. When updating host keys,
ssh will now search subsequent known_hosts files, but will add
updated host keys to the first specified file only. bz2738
* All: replace all calls to signal(2) with a wrapper around
sigaction(2). This wrapper blocks all other signals during the
handler preventing races between handlers, and sets SA_RESTART
which should reduce the potential for short read/write operations.
* sftp(1): fix a race condition in the SIGCHILD handler that could
turn in to a kill(-1); bz3084
* sshd(8): fix a case where valid (but extremely large) SSH channel
IDs were being incorrectly rejected. bz3098
* ssh(1): when checking host key fingerprints as answers to new
hostkey prompts, ignore whitespace surrounding the fingerprint
itself.
* All: wait for file descriptors to be readable or writeable during
non-blocking connect, not just readable. Prevents a timeout when
the server doesn't immediately send a banner (e.g. multiplexers
like sslh)
* sshd_config(5): document the sntrup4591761x25519-sha512@tinyssh.org
key exchange algorithm. PR#151
*) Fixed a fork protection issue. OpenSSL 1.1.1 introduced a rewritten random
number generator (RNG). This was intended to include protection in the
event of a fork() system call in order to ensure that the parent and child
processes did not share the same RNG state. However this protection was not
being used in the default case.
A partial mitigation for this issue is that the output from a high
precision timer is mixed into the RNG state so the likelihood of a parent
and child process sharing state is significantly reduced.
If an application already calls OPENSSL_init_crypto() explicitly using
OPENSSL_INIT_ATFORK then this problem does not occur at all.
(CVE-2019-1549)
[Matthias St. Pierre]
*) For built-in EC curves, ensure an EC_GROUP built from the curve name is
used even when parsing explicit parameters, when loading a serialized key
or calling `EC_GROUP_new_from_ecpkparameters()`/
`EC_GROUP_new_from_ecparameters()`.
This prevents bypass of security hardening and performance gains,
especially for curves with specialized EC_METHODs.
By default, if a key encoded with explicit parameters is loaded and later
serialized, the output is still encoded with explicit parameters, even if
internally a "named" EC_GROUP is used for computation.
[Nicola Tuveri]
*) Compute ECC cofactors if not provided during EC_GROUP construction. Before
this change, EC_GROUP_set_generator would accept order and/or cofactor as
NULL. After this change, only the cofactor parameter can be NULL. It also
does some minimal sanity checks on the passed order.
(CVE-2019-1547)
[Billy Bob Brumley]
*) Fixed a padding oracle in PKCS7_dataDecode and CMS_decrypt_set1_pkey.
An attack is simple, if the first CMS_recipientInfo is valid but the
second CMS_recipientInfo is chosen ciphertext. If the second
recipientInfo decodes to PKCS #1 v1.5 form plaintext, the correct
encryption key will be replaced by garbage, and the message cannot be
decoded, but if the RSA decryption fails, the correct encryption key is
used and the recipient will not notice the attack.
As a work around for this potential attack the length of the decrypted
key must be equal to the cipher default key length, in case the
certifiate is not given and all recipientInfo are tried out.
The old behaviour can be re-enabled in the CMS code by setting the
CMS_DEBUG_DECRYPT flag.
(CVE-2019-1563)
[Bernd Edlinger]
*) Early start up entropy quality from the DEVRANDOM seed source has been
improved for older Linux systems. The RAND subsystem will wait for
/dev/random to be producing output before seeding from /dev/urandom.
The seeded state is stored for future library initialisations using
a system global shared memory segment. The shared memory identifier
can be configured by defining OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID to
the desired value. The default identifier is 114.
[Paul Dale]
*) Correct the extended master secret constant on EBCDIC systems. Without this
fix TLS connections between an EBCDIC system and a non-EBCDIC system that
negotiate EMS will fail. Unfortunately this also means that TLS connections
between EBCDIC systems with this fix, and EBCDIC systems without this
fix will fail if they negotiate EMS.
[Matt Caswell]
*) Use Windows installation paths in the mingw builds
Mingw isn't a POSIX environment per se, which means that Windows
paths should be used for installation.
(CVE-2019-1552)
[Richard Levitte]
*) Changed DH_check to accept parameters with order q and 2q subgroups.
With order 2q subgroups the bit 0 of the private key is not secret
but DH_generate_key works around that by clearing bit 0 of the
private key for those. This avoids leaking bit 0 of the private key.
[Bernd Edlinger]
*) Significantly reduce secure memory usage by the randomness pools.
[Paul Dale]
*) Revert the DEVRANDOM_WAIT feature for Linux systems
The DEVRANDOM_WAIT feature added a select() call to wait for the
/dev/random device to become readable before reading from the
/dev/urandom device.
It turned out that this change had negative side effects on
performance which were not acceptable. After some discussion it
was decided to revert this feature and leave it up to the OS
resp. the platform maintainer to ensure a proper initialization
during early boot time.
[Matthias St. Pierre]
christos