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merge conflicts between OpenSSH-9.8 and 9.9
Import OpenSSH-9.9 (previous was 9.8) Changes: Future deprecation notice ========================= OpenSSH plans to remove support for the DSA signature algorithm in early 2025. This release disables DSA by default at compile time. DSA, as specified in the SSHv2 protocol, is inherently weak - being limited to a 160 bit private key and use of the SHA1 digest. Its estimated security level is only 80 bits symmetric equivalent. OpenSSH has disabled DSA keys by default since 2015 but has retained run-time optional support for them. DSA was the only mandatory-to- implement algorithm in the SSHv2 RFCs, mostly because alternative algorithms were encumbered by patents when the SSHv2 protocol was specified. This has not been the case for decades at this point and better algorithms are well supported by all actively-maintained SSH implementations. We do not consider the costs of maintaining DSA in OpenSSH to be justified and hope that removing it from OpenSSH can accelerate its wider deprecation in supporting cryptography libraries. Currently DSA is disabled at compile time. The final step of removing DSA support entirely is planned for the first OpenSSH release of 2025. DSA support may be re-enabled on OpenBSD by setting "DSAKEY=yes" in Makefile.inc. To enable DSA support in portable OpenSSH, pass the "--enable-dsa-keys" option to configure. Potentially-incompatible changes -------------------------------- * ssh(1): remove support for pre-authentication compression. OpenSSH has only supported post-authentication compression in the server for some years. Compression before authentication significantly increases the attack surface of SSH servers and risks creating oracles that reveal information about information sent during authentication. * ssh(1), sshd(8): processing of the arguments to the "Match" configuration directive now follows more shell-like rules for quoted strings, including allowing nested quotes and \-escaped characters. If configurations contained workarounds for the previous simplistic quote handling then they may need to be adjusted. If this is the case, it's most likely to be in the arguments to a "Match exec" confition. In this case, moving the command to be evaluated from the Match line to an external shell script is easiest way to preserve compatibility with both the old and new versions. Changes since OpenSSH 9.8 ========================= This release contains a number of new features and bugfixes. New features ------------ * ssh(1), sshd(8): add support for a new hybrid post-quantum key exchange based on the FIPS 203 Module-Lattice Key Enapsulation mechanism (ML-KEM) combined with X25519 ECDH as described by https://datatracker.ietf.org/doc/html/draft-kampanakis-curdle-ssh-pq-ke-03 This algorithm "mlkem768x25519-sha256" is available by default. * ssh(1): the ssh_config "Include" directive can now expand environment as well as the same set of %-tokens "Match Exec" supports. * sshd(8): add a sshd_config "RefuseConnection" option that, if set will terminate the connection at the first authentication request. * sshd(8): add a "refuseconnection" penalty class to sshd_config PerSourcePenalties that is applied when a connection is dropped by the new RefuseConnection keyword. * sshd(8): add a "Match invalid-user" predicate to sshd_config Match options that matches when the target username is not valid on the server. * ssh(1), sshd(8): update the Streamlined NTRUPrime code to a substantially faster implementation. * ssh(1), sshd(8): the hybrid Streamlined NTRUPrime/X25519 key exchange algorithm now has an IANA-assigned name in addition to the "@openssh.com" vendor extension name. This algorithm is now also available under this name "sntrup761x25519-sha512" * ssh(1), sshd(8), ssh-agent(1): prevent private keys from being included in core dump files for most of their lifespans. This is in addition to pre-existing controls in ssh-agent(1) and sshd(8) that prevented coredumps. This feature is supported on OpenBSD, Linux and FreeBSD. * All: convert key handling to use the libcrypto EVP_PKEY API, with the exception of DSA. * sshd(8): add a random amount of jitter (up to 4 seconds) to the grace login time to make its expiry unpredictable. Bugfixes -------- * sshd(8): relax absolute path requirement back to what it was prior to OpenSSH 9.8, which incorrectly required that sshd was started with an absolute path in inetd mode. bz3717 * sshd(8): fix regression introduced in openssh-9.8 that swapped the order of source and destination addresses in some sshd log messages. * sshd(8): do not apply authorized_keys options when signature verification fails. Prevents more restrictive key options being incorrectly applied to subsequent keys in authorized_keys. bz3733 * ssh-keygen(1): include pathname in some of ssh-keygen's passphrase prompts. Helps the user know what's going on when ssh-keygen is invoked via other tools. Requested in GHPR503 * ssh(1), ssh-add(1): make parsing user@host consistently look for the last '@' in the string rather than the first. This makes it possible to more consistently use usernames that contain '@' characters. * ssh(1), sshd(8): be more strict in parsing key type names. Only allow short names (e.g "rsa") in user-interface code and require full SSH protocol names (e.g. "ssh-rsa") everywhere else. bz3725 * regress: many performance and correctness improvements to the re-keying regression test. * ssh-keygen(1): clarify that ed25519 is the default key type generated and clarify that rsa-sha2-512 is the default signature scheme when RSA is in use. GHPR505 * sshd(8): fix minor memory leak in Subsystem option parsing; GHPR515 * All: additional hardening and consistency checks for the sshbuf code. * sshd(8): reduce default logingrace penalty to ensure that a single forgotton login that times out will be below the penalty threshold. * ssh(1): fix proxy multiplexing (-O proxy) bug. If a mux started with ControlPersist then later has a forwarding added using mux proxy connection and the forwarding was used, then when the mux proxy session terminated, the mux master process would issue a bad message that terminated the connection. Portability ----------- * sync contrib/ssh-copy-id to the latest upstream version. * regress: improve portablility for some awk(1) usage (e.g. Solaris) * In the contrib/redhat RPM spec file, without_openssl was previously incorrectly enabled unconditionally. * sshd(8) restore audit call before exit that regressed in openssh-9.8 Fixes an issue where the SSH_CONNECTION_ABANDON event was not recorded. * sshd(8): add support for class-imposed loging restrictions on FreeBSD. Allowing auth_hostok(3) and auth_timeok(3) to control logins. * Build fixes for Musl libc. * Fix detection of setres*id on GNU/Hurd
Pull up the following, requested by kim in ticket #1780: crypto/external/bsd/openssh/Makefile.inc up to 1.15 (+patch) crypto/external/bsd/openssh/bin/Makefile.inc up to 1.4 crypto/external/bsd/openssh/bin/scp/Makefile up to 1.6 crypto/external/bsd/openssh/bin/sftp/Makefile up to 1.11 crypto/external/bsd/openssh/bin/sftp-server/Makefile up to 1.4 crypto/external/bsd/openssh/bin/ssh/Makefile up to 1.20 crypto/external/bsd/openssh/bin/ssh-add/Makefile up to 1.3 crypto/external/bsd/openssh/bin/ssh-agent/Makefile up to 1.7 crypto/external/bsd/openssh/bin/ssh-keygen/Makefile up to 1.10 crypto/external/bsd/openssh/bin/ssh-keyscan/Makefile up to 1.6 crypto/external/bsd/openssh/bin/ssh-pkcs11-helper/Makefile up to 1.4 crypto/external/bsd/openssh/bin/sshd/Makefile up to 1.27 (+patch) crypto/external/bsd/openssh/dist/PROTOCOL.sshsig up to 1.1.1.2 crypto/external/bsd/openssh/dist/srclimit.c up to 1.3 crypto/external/bsd/openssh/dist/sftp-realpath.c up to 1.3 crypto/external/bsd/openssh/dist/sntrup761.c up to 1.3 crypto/external/bsd/openssh/dist/sntrup761.sh up to 1.1.1.2 crypto/external/bsd/openssh/dist/sshsig.c up to 1.12 crypto/external/bsd/openssh/dist/sshsig.h up to 1.1.1.5 crypto/external/bsd/openssh/dist/addr.c up to 1.6 crypto/external/bsd/openssh/dist/PROTOCOL.u2f up to 1.1.1.3 crypto/external/bsd/openssh/dist/sk-api.h up to 1.1.1.6 crypto/external/bsd/openssh/dist/sk-usbhid.c up to 1.9 crypto/external/bsd/openssh/dist/ssh-ecdsa-sk.c up to 1.4 crypto/external/bsd/openssh/dist/ssh-ed25519-sk.c up to 1.5 crypto/external/bsd/openssh/dist/ssh-sk-client.c up to 1.6 crypto/external/bsd/openssh/dist/ssh-sk-helper.8 up to 1.1.1.2 crypto/external/bsd/openssh/dist/ssh-sk-helper.c up to 1.7 crypto/external/bsd/openssh/dist/ssh-sk.c up to 1.8 crypto/external/bsd/openssh/dist/ssh-sk.h up to 1.1.1.2 crypto/external/bsd/openssh/dist/sshbuf-io.c up to 1.2 crypto/external/bsd/openssh/dist/addr.h up to 1.1.1.2 crypto/external/bsd/openssh/dist/kexsntrup761x25519.c up to 1.3 crypto/external/bsd/openssh/dist/cipher-chachapoly-libcrypto.c up to 1.3 crypto/external/bsd/openssh/dist/srclimit.h up to 1.1.1.1 crypto/external/bsd/openssh/dist/auth2-pubkeyfile.c up to 1.3 crypto/external/bsd/openssh/dist/sftp-usergroup.c up to 1.3 crypto/external/bsd/openssh/dist/sftp-usergroup.h up to 1.1.1.1 crypto/external/bsd/openssh/dist/ed25519.sh up to 1.1.1.1 crypto/external/bsd/openssh/dist/crc32.c delete crypto/external/bsd/openssh/dist/crc32.h delete crypto/external/bsd/openssh/dist/fe25519.c delete crypto/external/bsd/openssh/dist/fe25519.h delete crypto/external/bsd/openssh/dist/ge25519.c delete crypto/external/bsd/openssh/dist/ge25519.h delete crypto/external/bsd/openssh/dist/ge25519_base.data delete crypto/external/bsd/openssh/dist/kexsntrup4591761x25519.c delete crypto/external/bsd/openssh/dist/sc25519.c delete crypto/external/bsd/openssh/dist/sc25519.h delete crypto/external/bsd/openssh/dist/sntrup4591761.c delete crypto/external/bsd/openssh/dist/sntrup4591761.sh delete crypto/external/bsd/openssh/dist/uuencode.c delete crypto/external/bsd/openssh/dist/uuencode.h delete crypto/external/bsd/openssh/dist/verify.c delete crypto/external/bsd/openssh/dist/LICENCE up to 1.7 crypto/external/bsd/openssh/dist/PROTOCOL up to 1.23 crypto/external/bsd/openssh/dist/PROTOCOL.agent up to 1.15 crypto/external/bsd/openssh/dist/PROTOCOL.certkeys up to 1.13 crypto/external/bsd/openssh/dist/PROTOCOL.chacha20poly1305 up to 1.1.1.4 crypto/external/bsd/openssh/dist/PROTOCOL.key up to 1.1.1.3 crypto/external/bsd/openssh/dist/PROTOCOL.krl up to 1.1.1.5 crypto/external/bsd/openssh/dist/PROTOCOL.mux up to 1.12 crypto/external/bsd/openssh/dist/addrmatch.c up to 1.15 crypto/external/bsd/openssh/dist/auth-krb5.c up to 1.16 crypto/external/bsd/openssh/dist/auth-options.c up to 1.29 crypto/external/bsd/openssh/dist/auth-options.h up to 1.15 crypto/external/bsd/openssh/dist/auth-pam.c up to 1.21 crypto/external/bsd/openssh/dist/auth-passwd.c up to 1.13 crypto/external/bsd/openssh/dist/auth-rhosts.c up to 1.16 crypto/external/bsd/openssh/dist/auth.c up to 1.34 crypto/external/bsd/openssh/dist/auth.h up to 1.23 crypto/external/bsd/openssh/dist/auth2-chall.c up to 1.19 crypto/external/bsd/openssh/dist/auth2-gss.c up to 1.17 crypto/external/bsd/openssh/dist/auth2-hostbased.c up to 1.23 crypto/external/bsd/openssh/dist/auth2-kbdint.c up to 1.15 crypto/external/bsd/openssh/dist/auth2-krb5.c up to 1.10 crypto/external/bsd/openssh/dist/auth2-none.c up to 1.14 crypto/external/bsd/openssh/dist/auth2-passwd.c up to 1.16 crypto/external/bsd/openssh/dist/auth2-pubkey.c up to 1.34 crypto/external/bsd/openssh/dist/auth2.c up to 1.29 crypto/external/bsd/openssh/dist/authfd.c up to 1.27 crypto/external/bsd/openssh/dist/authfd.h up to 1.17 crypto/external/bsd/openssh/dist/authfile.c up to 1.28 crypto/external/bsd/openssh/dist/authfile.h up to 1.10 crypto/external/bsd/openssh/dist/canohost.c up to 1.16 crypto/external/bsd/openssh/dist/chacha.c up to 1.6 crypto/external/bsd/openssh/dist/chacha.h up to 1.3 crypto/external/bsd/openssh/dist/channels.c up to 1.42 crypto/external/bsd/openssh/dist/channels.h up to 1.26 crypto/external/bsd/openssh/dist/cipher-chachapoly.c up to 1.7 crypto/external/bsd/openssh/dist/cipher-chachapoly.h up to 1.3 crypto/external/bsd/openssh/dist/cipher.c up to 1.21 crypto/external/bsd/openssh/dist/cipher.h up to 1.17 crypto/external/bsd/openssh/dist/clientloop.c up to 1.39 crypto/external/bsd/openssh/dist/clientloop.h up to 1.18 crypto/external/bsd/openssh/dist/compat.c up to 1.26 crypto/external/bsd/openssh/dist/compat.h up to 1.18 crypto/external/bsd/openssh/dist/crypto_api.h up to 1.5 crypto/external/bsd/openssh/dist/dh.c up to 1.20 crypto/external/bsd/openssh/dist/dh.h up to 1.13 crypto/external/bsd/openssh/dist/digest-libc.c up to 1.8 crypto/external/bsd/openssh/dist/digest-openssl.c up to 1.9 crypto/external/bsd/openssh/dist/dispatch.c up to 1.11 crypto/external/bsd/openssh/dist/dns.c up to 1.23 crypto/external/bsd/openssh/dist/dns.h up to 1.13 crypto/external/bsd/openssh/dist/ed25519.c up to 1.6 crypto/external/bsd/openssh/dist/fatal.c up to 1.7 crypto/external/bsd/openssh/dist/getrrsetbyname.c up to 1.6 crypto/external/bsd/openssh/dist/gss-genr.c up to 1.11 crypto/external/bsd/openssh/dist/gss-serv.c up to 1.15 crypto/external/bsd/openssh/dist/hash.c up to 1.7 crypto/external/bsd/openssh/dist/hmac.c up to 1.8 crypto/external/bsd/openssh/dist/hostfile.c up to 1.23 crypto/external/bsd/openssh/dist/hostfile.h up to 1.11 crypto/external/bsd/openssh/dist/includes.h up to 1.9 crypto/external/bsd/openssh/dist/kex.c up to 1.34 crypto/external/bsd/openssh/dist/kex.h up to 1.24 crypto/external/bsd/openssh/dist/kexdh.c up to 1.10 crypto/external/bsd/openssh/dist/kexgen.c up to 1.7 crypto/external/bsd/openssh/dist/kexgexc.c up to 1.17 crypto/external/bsd/openssh/dist/kexgexs.c up to 1.23 crypto/external/bsd/openssh/dist/krl.c up to 1.23 crypto/external/bsd/openssh/dist/krl.h up to 1.6 crypto/external/bsd/openssh/dist/ldapauth.c up to 1.8 crypto/external/bsd/openssh/dist/ldapauth.h up to 1.6 crypto/external/bsd/openssh/dist/log.c up to 1.27 crypto/external/bsd/openssh/dist/log.h up to 1.17 crypto/external/bsd/openssh/dist/mac.c up to 1.16 crypto/external/bsd/openssh/dist/match.c up to 1.16 crypto/external/bsd/openssh/dist/match.h up to 1.11 crypto/external/bsd/openssh/dist/misc.c up to 1.35 crypto/external/bsd/openssh/dist/misc.h up to 1.27 crypto/external/bsd/openssh/dist/moduli up to 1.10 crypto/external/bsd/openssh/dist/moduli.c up to 1.17 crypto/external/bsd/openssh/dist/monitor.c up to 1.43 crypto/external/bsd/openssh/dist/monitor.h up to 1.13 crypto/external/bsd/openssh/dist/monitor_fdpass.c up to 1.9 crypto/external/bsd/openssh/dist/monitor_wrap.c up to 1.34 crypto/external/bsd/openssh/dist/monitor_wrap.h up to 1.23 crypto/external/bsd/openssh/dist/msg.c up to 1.11 crypto/external/bsd/openssh/dist/mux.c up to 1.35 crypto/external/bsd/openssh/dist/myproposal.h up to 1.24 crypto/external/bsd/openssh/dist/namespace.h up to 1.10 crypto/external/bsd/openssh/dist/nchan.c up to 1.14 crypto/external/bsd/openssh/dist/packet.c up to 1.50 crypto/external/bsd/openssh/dist/packet.h up to 1.26 crypto/external/bsd/openssh/dist/pathnames.h up to 1.15 crypto/external/bsd/openssh/dist/pfilter.c up to 1.8 (+patch) crypto/external/bsd/openssh/dist/poly1305.c up to 1.6 crypto/external/bsd/openssh/dist/progressmeter.c up to 1.15 crypto/external/bsd/openssh/dist/readconf.c up to 1.44 crypto/external/bsd/openssh/dist/readconf.h up to 1.34 crypto/external/bsd/openssh/dist/readpass.c up to 1.18 crypto/external/bsd/openssh/dist/rijndael.h up to 1.3 crypto/external/bsd/openssh/dist/sandbox-pledge.c up to 1.3 crypto/external/bsd/openssh/dist/sandbox-rlimit.c up to 1.7 crypto/external/bsd/openssh/dist/scp.1 up to 1.31 crypto/external/bsd/openssh/dist/scp.c up to 1.41 crypto/external/bsd/openssh/dist/servconf.c up to 1.44 crypto/external/bsd/openssh/dist/servconf.h up to 1.30 crypto/external/bsd/openssh/dist/serverloop.c up to 1.35 crypto/external/bsd/openssh/dist/session.c up to 1.38 crypto/external/bsd/openssh/dist/session.h up to 1.10 crypto/external/bsd/openssh/dist/sftp-client.c up to 1.35 crypto/external/bsd/openssh/dist/sftp-client.h up to 1.18 crypto/external/bsd/openssh/dist/sftp-common.c up to 1.14 crypto/external/bsd/openssh/dist/sftp-common.h up to 1.8 crypto/external/bsd/openssh/dist/sftp-glob.c up to 1.15 crypto/external/bsd/openssh/dist/sftp-server-main.c up to 1.8 crypto/external/bsd/openssh/dist/sftp-server.8 up to 1.14 crypto/external/bsd/openssh/dist/sftp-server.c up to 1.30 crypto/external/bsd/openssh/dist/sftp.1 up to 1.30 crypto/external/bsd/openssh/dist/sftp.c up to 1.39 crypto/external/bsd/openssh/dist/ssh-add.1 up to 1.18 crypto/external/bsd/openssh/dist/ssh-add.c up to 1.30 crypto/external/bsd/openssh/dist/ssh-agent.1 up to 1.19 crypto/external/bsd/openssh/dist/ssh-agent.c up to 1.37 crypto/external/bsd/openssh/dist/ssh-dss.c up to 1.18 crypto/external/bsd/openssh/dist/ssh-ecdsa.c up to 1.15 crypto/external/bsd/openssh/dist/ssh-ed25519.c up to 1.10 crypto/external/bsd/openssh/dist/ssh-gss.h up to 1.10 crypto/external/bsd/openssh/dist/ssh-keygen.1 up to 1.34 crypto/external/bsd/openssh/dist/ssh-keygen.c up to 1.46 crypto/external/bsd/openssh/dist/ssh-keyscan.1 up to 1.18 crypto/external/bsd/openssh/dist/ssh-keyscan.c up to 1.32 crypto/external/bsd/openssh/dist/ssh-keysign.8 up to 1.14 crypto/external/bsd/openssh/dist/ssh-keysign.c up to 1.24 crypto/external/bsd/openssh/dist/ssh-pkcs11-client.c up to 1.19 crypto/external/bsd/openssh/dist/ssh-pkcs11-helper.8 up to 1.12 crypto/external/bsd/openssh/dist/ssh-pkcs11-helper.c up to 1.22 crypto/external/bsd/openssh/dist/ssh-pkcs11.c up to 1.26 crypto/external/bsd/openssh/dist/ssh-pkcs11.h up to 1.9 crypto/external/bsd/openssh/dist/ssh-rsa.c up to 1.19 crypto/external/bsd/openssh/dist/ssh-xmss.c up to 1.6 crypto/external/bsd/openssh/dist/ssh.1 up to 1.39 crypto/external/bsd/openssh/dist/ssh.c up to 1.45 crypto/external/bsd/openssh/dist/ssh.h up to 1.13 crypto/external/bsd/openssh/dist/ssh2.h up to 1.15 crypto/external/bsd/openssh/dist/ssh_api.c up to 1.15 crypto/external/bsd/openssh/dist/ssh_config up to 1.16 crypto/external/bsd/openssh/dist/ssh_config.5 up to 1.40 crypto/external/bsd/openssh/dist/sshbuf-getput-basic.c up to 1.12 crypto/external/bsd/openssh/dist/sshbuf-getput-crypto.c up to 1.11 crypto/external/bsd/openssh/dist/sshbuf-misc.c up to 1.14 crypto/external/bsd/openssh/dist/sshbuf.c up to 1.14 crypto/external/bsd/openssh/dist/sshbuf.h up to 1.19 crypto/external/bsd/openssh/dist/sshconnect.c up to 1.37 crypto/external/bsd/openssh/dist/sshconnect.h up to 1.17 crypto/external/bsd/openssh/dist/sshconnect2.c up to 1.46 crypto/external/bsd/openssh/dist/sshd.8 up to 1.31 crypto/external/bsd/openssh/dist/sshd.c up to 1.50 crypto/external/bsd/openssh/dist/sshd_config up to 1.28 crypto/external/bsd/openssh/dist/sshd_config.5 up to 1.42 crypto/external/bsd/openssh/dist/ssherr.c up to 1.10 crypto/external/bsd/openssh/dist/ssherr.h up to 1.4 crypto/external/bsd/openssh/dist/sshkey-xmss.c up to 1.10 crypto/external/bsd/openssh/dist/sshkey-xmss.h up to 1.5 crypto/external/bsd/openssh/dist/sshkey.c up to 1.32 crypto/external/bsd/openssh/dist/sshkey.h up to 1.19 crypto/external/bsd/openssh/dist/sshlogin.c up to 1.13 crypto/external/bsd/openssh/dist/sshpty.c up to 1.8 crypto/external/bsd/openssh/dist/ttymodes.c up to 1.12 crypto/external/bsd/openssh/dist/uidswap.c up to 1.10 crypto/external/bsd/openssh/dist/umac.c up to 1.22 crypto/external/bsd/openssh/dist/umac.h up to 1.10 crypto/external/bsd/openssh/dist/utf8.c up to 1.9 crypto/external/bsd/openssh/dist/utf8.h up to 1.5 crypto/external/bsd/openssh/dist/version.h up to 1.44 crypto/external/bsd/openssh/dist/xmalloc.c up to 1.13 crypto/external/bsd/openssh/dist/xmalloc.h up to 1.16 crypto/external/bsd/openssh/dist/xmss_hash.c up to 1.3 crypto/external/bsd/openssh/dist/moduli-gen/Makefile up to 1.3 crypto/external/bsd/openssh/dist/moduli-gen/moduli-gen.sh up to 1.1.1.3 crypto/external/bsd/openssh/dist/moduli-gen/moduli.2048 up to 1.16 crypto/external/bsd/openssh/dist/moduli-gen/moduli.3072 up to 1.18 crypto/external/bsd/openssh/dist/moduli-gen/moduli.4096 up to 1.18 crypto/external/bsd/openssh/dist/moduli-gen/moduli.6144 up to 1.18 crypto/external/bsd/openssh/dist/moduli-gen/moduli.7680 up to 1.18 crypto/external/bsd/openssh/dist/moduli-gen/moduli.8192 up to 1.18 crypto/external/bsd/openssh/lib/Makefile up to 1.38 crypto/external/bsd/openssh/lib/shlib_version up to 1.36 crypto/external/bsd/openssh/openssh2netbsd up to 1.4 lib/libpam/modules/pam_ssh/Makefile up to 1.13 lib/libpam/modules/pam_ssh/pam_ssh.c up to 1.30 distrib/sets/lists/base/shl.mi (apply patch) distrib/sets/lists/debug/shl.mi (apply patch) doc/3RDPARTY (apply patch) Update OpenSSH to 9.6.
Merge differences between openssh-8.8 and openssh-8.9
Import OpenSSH 8.9. Future deprecation notice ========================= A near-future release of OpenSSH will switch scp(1) from using the legacy scp/rcp protocol to using SFTP by default. Legacy scp/rcp performs wildcard expansion of remote filenames (e.g. "scp host:* .") through the remote shell. This has the side effect of requiring double quoting of shell meta-characters in file names included on scp(1) command-lines, otherwise they could be interpreted as shell commands on the remote side. This creates one area of potential incompatibility: scp(1) when using the SFTP protocol no longer requires this finicky and brittle quoting, and attempts to use it may cause transfers to fail. We consider the removal of the need for double-quoting shell characters in file names to be a benefit and do not intend to introduce bug-compatibility for legacy scp/rcp in scp(1) when using the SFTP protocol. Another area of potential incompatibility relates to the use of remote paths relative to other user's home directories, for example - "scp host:~user/file /tmp". The SFTP protocol has no native way to expand a ~user path. However, sftp-server(8) in OpenSSH 8.7 and later support a protocol extension "expand-path@openssh.com" to support this. Security Near Miss ================== * sshd(8): fix an integer overflow in the user authentication path that, in conjunction with other logic errors, could have yielded unauthenticated access under difficult to exploit conditions. This situation is not exploitable because of independent checks in the privilege separation monitor. Privilege separation has been enabled by default in since openssh-3.2.2 (released in 2002) and has been mandatory since openssh-7.5 (released in 2017). Moreover, portable OpenSSH has used toolchain features available in most modern compilers to abort on signed integer overflow since openssh-6.5 (released in 2014). Thanks to Malcolm Stagg for finding and reporting this bug. Potentially-incompatible changes ================================ * sshd(8), portable OpenSSH only: this release removes in-built support for MD5-hashed passwords. If you require these on your system then we recommend linking against libxcrypt or similar. * This release modifies the FIDO security key middleware interface and increments SSH_SK_VERSION_MAJOR. Changes since OpenSSH 8.8 ========================= This release includes a number of new features. New features ------------ * ssh(1), sshd(8), ssh-add(1), ssh-agent(1): add a system for restricting forwarding and use of keys added to ssh-agent(1) A detailed description of the feature is available at https://www.openssh.com/agent-restrict.html and the protocol extensions are documented in the PROTOCOL and PROTOCOL.agent files in the source release. * ssh(1), sshd(8): add the sntrup761x25519-sha512@openssh.com hybrid ECDH/x25519 + Streamlined NTRU Prime post-quantum KEX to the default KEXAlgorithms list (after the ECDH methods but before the prime-group DH ones). The next release of OpenSSH is likely to make this key exchange the default method. * ssh-keygen(1): when downloading resident keys from a FIDO token, pass back the user ID that was used when the key was created and append it to the filename the key is written to (if it is not the default). Avoids keys being clobbered if the user created multiple resident keys with the same application string but different user IDs. * ssh-keygen(1), ssh(1), ssh-agent(1): better handling for FIDO keys on tokens that provide user verification (UV) on the device itself, including biometric keys, avoiding unnecessary PIN prompts. * ssh-keygen(1): add "ssh-keygen -Y match-principals" operation to perform matching of principals names against an allowed signers file. To be used towards a TOFU model for SSH signatures in git. * ssh-add(1), ssh-agent(1): allow pin-required FIDO keys to be added to ssh-agent(1). $SSH_ASKPASS will be used to request the PIN at authentication time. * ssh-keygen(1): allow selection of hash at sshsig signing time (either sha512 (default) or sha256). * ssh(1), sshd(8): read network data directly to the packet input buffer instead indirectly via a small stack buffer. Provides a modest performance improvement. * ssh(1), sshd(8): read data directly to the channel input buffer, providing a similar modest performance improvement. * ssh(1): extend the PubkeyAuthentication configuration directive to accept yes|no|unbound|host-bound to allow control over one of the protocol extensions used to implement agent-restricted keys. Bugfixes -------- * sshd(8): document that CASignatureAlgorithms, ExposeAuthInfo and PubkeyAuthOptions can be used in a Match block. PR#277. * sshd(8): fix possible string truncation when constructing paths to .rhosts/.shosts files with very long user home directory names. * ssh-keysign(1): unbreak for KEX algorithms that use SHA384/512 exchange hashes * ssh(1): don't put the TTY into raw mode when SessionType=none, avoids ^C being unable to kill such a session. bz3360 * scp(1): fix some corner-case bugs in SFTP-mode handling of ~-prefixed paths. * ssh(1): unbreak hostbased auth using RSA keys. Allow ssh(1) to select RSA keys when only RSA/SHA2 signature algorithms are configured (this is the default case). Previously RSA keys were not being considered in the default case. * ssh-keysign(1): make ssh-keysign use the requested signature algorithm and not the default for the key type. Part of unbreaking hostbased auth for RSA/SHA2 keys. * ssh(1): stricter UpdateHostkey signature verification logic on the client- side. Require RSA/SHA2 signatures for RSA hostkeys except when RSA/SHA1 was explicitly negotiated during initial KEX; bz3375 * ssh(1), sshd(8): fix signature algorithm selection logic for UpdateHostkeys on the server side. The previous code tried to prefer RSA/SHA2 for hostkey proofs of RSA keys, but missed some cases. This will use RSA/SHA2 signatures for RSA keys if the client proposed these algorithms in initial KEX. bz3375 * All: convert all uses of select(2)/pselect(2) to poll(2)/ppoll(2). This includes the mainloops in ssh(1), ssh-agent(1), ssh-agent(1) and sftp-server(8), as well as the sshd(8) listen loop and all other FD read/writability checks. On platforms with missing or broken poll(2)/ppoll(2) syscalls a select(2)-based compat shim is available. * ssh-keygen(1): the "-Y find-principals" command was verifying key validity when using ca certs but not with simple key lifetimes within the allowed signers file. * ssh-keygen(1): make sshsig verify-time argument parsing optional * sshd(8): fix truncation in rhosts/shosts path construction. * ssh(1), ssh-agent(1): avoid xmalloc(0) for PKCS#11 keyid for ECDSA keys (we already did this for RSA keys). Avoids fatal errors for PKCS#11 libraries that return empty keyid, e.g. Microchip ATECC608B "cryptoauthlib"; bz#3364 * ssh(1), ssh-agent(1): improve the testing of credentials against inserted FIDO: ask the token whether a particular key belongs to it in cases where the token supports on-token user-verification (e.g. biometrics) rather than just assuming that it will accept it. Will reduce spurious "Confirm user presence" notifications for key handles that relate to FIDO keys that are not currently inserted in at least some cases. bz3366 * ssh(1), sshd(8): correct value for IPTOS_DSCP_LE. It needs to allow for the preceding two ECN bits. bz#3373 * ssh-keygen(1): add missing -O option to usage() for the "-Y sign" option. * ssh-keygen(1): fix a NULL deref when using the find-principals function, when matching an allowed_signers line that contains a namespace restriction, but no restriction specified on the command-line * ssh-agent(1): fix memleak in process_extension(); oss-fuzz issue #42719 * ssh(1): suppress "Connection to xxx closed" messages when LogLevel is set to "error" or above. bz3378 * ssh(1), sshd(8): use correct zlib flags when inflate(3)-ing compressed packet data. bz3372 * scp(1): when recursively transferring files in SFTP mode, create the destination directory if it doesn't already exist to match scp(1) in legacy RCP mode behaviour. * scp(1): many improvements in error message consistency between scp(1) in SFTP mode vs legacy RCP mode. * sshd(8): fix potential race in SIGTERM handling PR#289 * ssh(1), ssh(8): since DSA keys are deprecated, move them to the end of the default list of public keys so that they will be tried last. PR#295 * ssh-keygen(1): allow 'ssh-keygen -Y find-principals' to match wildcard principals in allowed_signers files Portability ----------- * ssh(1), sshd(8): don't trust closefrom(2) on Linux. glibc's implementation does not work in a chroot when the kernel does not have close_range(2). It tries to read from /proc/self/fd and when that fails dies with an assertion of sorts. Instead, call close_range(2) directly from our compat code and fall back if that fails. bz#3349, * OS X poll(2) is broken; use compat replacement. For character- special devices like /dev/null, Darwin's poll(2) returns POLLNVAL when polled with POLLIN. Apparently this is Apple bug 3710161 - not public but a websearch will find other OSS projects rediscovering it periodically since it was first identified in 2005. * Correct handling of exceptfds/POLLPRI in our select(2)-based poll(2)/ppoll(2) compat implementation. * Cygwin: correct checking of mbstowcs() return value. * Add a basic SECURITY.md that refers people to the openssh.com website. * Enable additional compiler warnings and toolchain hardening flags, including -Wbitwise-instead-of-logical, -Wmisleading-indentation, -fzero-call-used-regs and -ftrivial-auto-var-init. * HP/UX. Use compat getline(3) on HP-UX 10.x, where the libc version is not reliable.
Merge local changes between 8.5 and 8.6
Import OpenSSH-8.6:
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.
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
Security
========
* sshd(8): OpenSSH 8.5 introduced the LogVerbose keyword. When this
option was enabled with a set of patterns that activated logging
in code that runs in the low-privilege sandboxed sshd process, the
log messages were constructed in such a way that printf(3) format
strings could effectively be specified the low-privilege code.
An attacker who had sucessfully exploited the low-privilege
process could use this to escape OpenSSH's sandboxing and attack
the high-privilege process. Exploitation of this weakness is
highly unlikely in practice as the LogVerbose option is not
enabled by default and is typically only used for debugging. No
vulnerabilities in the low-privilege process are currently known
to exist.
Thanks to Ilja Van Sprundel for reporting this bug.
Changes since OpenSSH 8.5
=========================
This release contains mostly bug fixes.
New features
------------
* sftp-server(8): add a new limits@openssh.com protocol extension
that allows a client to discover various server limits, including
maximum packet size and maximum read/write length.
* sftp(1): use the new limits@openssh.com extension (when available)
to select better transfer lengths in the client.
* sshd(8): Add ModuliFile keyword to sshd_config to specify the
location of the "moduli" file containing the groups for DH-GEX.
* unit tests: Add a TEST_SSH_ELAPSED_TIMES environment variable to
enable printing of the elapsed time in seconds of each test.
Bugfixes
--------
* ssh_config(5), sshd_config(5): sync CASignatureAlgorithms lists in
manual pages with the current default. GHPR#174
* ssh(1): ensure that pkcs11_del_provider() is called before exit.
GHPR#234
* ssh(1), sshd(8): fix problems in string->argv conversion. Multiple
backslashes were not being dequoted correctly and quoted space in
the middle of a string was being incorrectly split. GHPR#223
* ssh(1): return non-zero exit status when killed by signal; bz#3281
* sftp-server(8): increase maximum SSH2_FXP_READ to match the maximum
packet size. Also handle zero-length reads that are not explicitly
banned by the spec.
Portability
-----------
* sshd(8): don't mistakenly exit on transient read errors on the
network socket (e.g. EINTR, EAGAIN); bz3297
* Create a dedicated contrib/gnome-ssk-askpass3.c source instead of
building it from the same file as used for GNOME2. Use the GNOME3
gdk_seat_grab() to manage keyboard/mouse/server grabs for better
compatibility with Wayland.
* Fix portability build errors bz3293 bz3292 bz3291 bz3278
* sshd(8): soft-disallow the fstatat64 syscall in the Linux
seccomp-bpf sandbox. bz3276
* unit tests: enable autoopt and misc unit tests that were
previously skipped
merge local changes between openssh 8.4 and 8.5
OpenSSH 8.5/8.5p1 (2021-03-03)
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
Mostly merge changes from HEAD upto 20200411
Merge conflicts
OpenSSH 8.2/8.2p1 (2020-02-14)
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
merge openssh-8.1
OpenSSH 8.1 was released on 2019-10-09. 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: http://www.openssh.com/donations.html Security ======== * ssh(1), sshd(8), ssh-add(1), ssh-keygen(1): an exploitable integer overflow bug was found in the private key parsing code for the XMSS key type. This key type is still experimental and support for it is not compiled by default. No user-facing autoconf option exists in portable OpenSSH to enable it. This bug was found by Adam Zabrocki and reported via SecuriTeam's SSD program. * ssh(1), sshd(8), ssh-agent(1): add protection for private keys at rest in RAM against speculation and memory side-channel attacks like Spectre, Meltdown and Rambleed. This release encrypts private keys when they are not in use with a symmetric key that is derived from a relatively large "prekey" consisting of random data (currently 16KB). Potentially-incompatible changes ================================ This release includes a number of changes that may affect existing configurations: * ssh-keygen(1): when acting as a CA and signing certificates with an RSA key, default to using the rsa-sha2-512 signature algorithm. Certificates signed by RSA keys will therefore be incompatible with OpenSSH versions prior to 7.2 unless the default is overridden (using "ssh-keygen -t ssh-rsa -s ...").
Sync with HEAD
file kexgen.c was added on branch phil-wifi on 2019-06-10 21:41:12 +0000
merge conflicts.
Import 8.0: Security ======== This release contains mitigation for a weakness in the scp(1) tool and protocol (CVE-2019-6111): when copying files from a remote system to a local directory, scp(1) did not verify that the filenames that the server sent matched those requested by the client. This could allow a hostile server to create or clobber unexpected local files with attacker-controlled content. This release adds client-side checking that the filenames sent from the server match the command-line request, The scp protocol is outdated, inflexible and not readily fixed. We recommend the use of more modern protocols like sftp and rsync for file transfer instead. Potentially-incompatible changes ================================ This release includes a number of changes that may affect existing configurations: * scp(1): Relating to the above changes to scp(1); the scp protocol relies on the remote shell for wildcard expansion, so there is no infallible way for the client's wildcard matching to perfectly reflect the server's. If there is a difference between client and server wildcard expansion, the client may refuse files from the server. For this reason, we have provided a new "-T" flag to scp that disables these client-side checks at the risk of reintroducing the attack described above. * sshd(8): Remove support for obsolete "host/port" syntax. Slash- separated host/port was added in 2001 as an alternative to host:port syntax for the benefit of IPv6 users. These days there are establised standards for this like [::1]:22 and the slash syntax is easily mistaken for CIDR notation, which OpenSSH supports for some things. Remove the slash notation from ListenAddress and PermitOpen; bz#2335 Changes since OpenSSH 7.9 ========================= This release is focused on new features and internal refactoring. New Features ------------ * ssh(1), ssh-agent(1), ssh-add(1): Add support for ECDSA keys in PKCS#11 tokens. * ssh(1), sshd(8): Add experimental quantum-computing resistant key exchange method, based on a combination of Streamlined NTRU Prime 4591^761 and X25519. * ssh-keygen(1): Increase the default RSA key size to 3072 bits, following NIST Special Publication 800-57's guidance for a 128-bit equivalent symmetric security level. * ssh(1): Allow "PKCS11Provider=none" to override later instances of the PKCS11Provider directive in ssh_config; bz#2974 * sshd(8): Add a log message for situations where a connection is dropped for attempting to run a command but a sshd_config ForceCommand=internal-sftp restriction is in effect; bz#2960 * ssh(1): When prompting whether to record a new host key, accept the key fingerprint as a synonym for "yes". This allows the user to paste a fingerprint obtained out of band at the prompt and have the client do the comparison for you. * ssh-keygen(1): When signing multiple certificates on a single command-line invocation, allow automatically incrementing the certificate serial number. * scp(1), sftp(1): Accept -J option as an alias to ProxyJump on the scp and sftp command-lines. * ssh-agent(1), ssh-pkcs11-helper(8), ssh-add(1): Accept "-v" command-line flags to increase the verbosity of output; pass verbose flags though to subprocesses, such as ssh-pkcs11-helper started from ssh-agent. * ssh-add(1): Add a "-T" option to allowing testing whether keys in an agent are usable by performing a signature and a verification. * sftp-server(8): Add a "lsetstat@openssh.com" protocol extension that replicates the functionality of the existing SSH2_FXP_SETSTAT operation but does not follow symlinks. bz#2067 * sftp(1): Add "-h" flag to chown/chgrp/chmod commands to request they do not follow symlinks. * sshd(8): Expose $SSH_CONNECTION in the PAM environment. This makes the connection 4-tuple available to PAM modules that wish to use it in decision-making. bz#2741 * sshd(8): Add a ssh_config "Match final" predicate Matches in same pass as "Match canonical" but doesn't require hostname canonicalisation be enabled. bz#2906 * sftp(1): Support a prefix of '@' to suppress echo of sftp batch commands; bz#2926 * ssh-keygen(1): When printing certificate contents using "ssh-keygen -Lf /path/certificate", include the algorithm that the CA used to sign the cert. Bugfixes -------- * sshd(8): Fix authentication failures when sshd_config contains "AuthenticationMethods any" inside a Match block that overrides a more restrictive default. * sshd(8): Avoid sending duplicate keepalives when ClientAliveCount is enabled. * sshd(8): Fix two race conditions related to SIGHUP daemon restart. Remnant file descriptors in recently-forked child processes could block the parent sshd's attempt to listen(2) to the configured addresses. Also, the restarting parent sshd could exit before any child processes that were awaiting their re-execution state had completed reading it, leaving them in a fallback path. * ssh(1): Fix stdout potentially being redirected to /dev/null when ProxyCommand=- was in use. * sshd(8): Avoid sending SIGPIPE to child processes if they attempt to write to stderr after their parent processes have exited; bz#2071 * ssh(1): Fix bad interaction between the ssh_config ConnectTimeout and ConnectionAttempts directives - connection attempts after the first were ignoring the requested timeout; bz#2918 * ssh-keyscan(1): Return a non-zero exit status if no keys were found; bz#2903 * scp(1): Sanitize scp filenames to allow UTF-8 characters without terminal control sequences; bz#2434 * sshd(8): Fix confusion between ClientAliveInterval and time-based RekeyLimit that could cause connections to be incorrectly closed. bz#2757 * ssh(1), ssh-add(1): Correct some bugs in PKCS#11 token PIN handling at initial token login. The attempt to read the PIN could be skipped in some cases, particularly on devices with integrated PIN readers. This would lead to an inability to retrieve keys from these tokens. bz#2652 * ssh(1), ssh-add(1): Support keys on PKCS#11 tokens that set the CKA_ALWAYS_AUTHENTICATE flag by requring a fresh login after the C_SignInit operation. bz#2638 * ssh(1): Improve documentation for ProxyJump/-J, clarifying that local configuration does not apply to jump hosts. * ssh-keygen(1): Clarify manual - ssh-keygen -e only writes public keys, not private. * ssh(1), sshd(8): be more strict in processing protocol banners, allowing \r characters only immediately before \n. * Various: fix a number of memory leaks, including bz#2942 and bz#2938 * scp(1), sftp(1): fix calculation of initial bandwidth limits. Account for bytes written before the timer starts and adjust the schedule on which recalculations are performed. Avoids an initial burst of traffic and yields more accurate bandwidth limits; bz#2927 * sshd(8): Only consider the ext-info-c extension during the initial key eschange. It shouldn't be sent in subsequent ones, but if it is present we should ignore it. This prevents sshd from sending a SSH_MSG_EXT_INFO for REKEX for buggy these clients. bz#2929 * ssh-keygen(1): Clarify manual that ssh-keygen -F (find host in authorized_keys) and -R (remove host from authorized_keys) options may accept either a bare hostname or a [hostname]:port combo. bz#2935 * ssh(1): Don't attempt to connect to empty SSH_AUTH_SOCK; bz#2936 * sshd(8): Silence error messages when sshd fails to load some of the default host keys. Failure to load an explicitly-configured hostkey is still an error, and failure to load any host key is still fatal. pr/103 * ssh(1): Redirect stderr of ProxyCommands to /dev/null when ssh is started with ControlPersist; prevents random ProxyCommand output from interfering with session output. * ssh(1): The ssh client was keeping a redundant ssh-agent socket (leftover from authentication) around for the life of the connection; bz#2912 * sshd(8): Fix bug in HostbasedAcceptedKeyTypes and PubkeyAcceptedKeyTypes options. If only RSA-SHA2 siganture types were specified, then authentication would always fail for RSA keys as the monitor checks only the base key (not the signature algorithm) type against *AcceptedKeyTypes. bz#2746 * ssh(1): Request correct signature types from ssh-agent when certificate keys and RSA-SHA2 signatures are in use. Portability ----------- * sshd(8): On Cygwin, run as SYSTEM where possible, using S4U for token creation if it supports MsV1_0 S4U Logon. * sshd(8): On Cygwin, use custom user/group matching code that respects the OS' behaviour of case-insensitive matching. * sshd(8): Don't set $MAIL if UsePAM=yes as PAM typically specifies the user environment if it's enabled; bz#2937 * sshd(8) Cygwin: Change service name to cygsshd to avoid collision with Microsoft's OpenSSH port. * Allow building against OpenSSL -dev (3.x) * Fix a number of build problems against version configurations and versions of OpenSSL. Including bz#2931 and bz#2921 * Improve warnings in cygwin service setup. bz#2922 * Remove hardcoded service name in cygwin setup. bz#2922
Initial revision