Bug#868009: Immediate disconnect after successful authentication when "UsePrivilegeSeparation sandbox" is used
ok, please see the attached file.
I ran it with
/usr/sbin/sshd -p 2222 -ddd -o UsePrivilegeSeparation=sandbox
Thanks,
Simon
Am 2017-07-11 um 10:37 schrieb Colin Watson:
> On Tue, Jul 11, 2017 at 08:43:58AM +0200, Simon Kainz wrote:
>> When using the default
>>
>> UsePrivilegeSeparation sandbox
>>
>> i am unable to connect via SSH.
>>
>> This even does not work when i try it locally, eg.
>>
>> ssh skainz@127.0.0.1
>>
>>
>> SSH fails right after pre-authentication. Systme log tells me, the
>> authentication itself works correctly, but i get disconnected afterwards.
>>
>> If i set
>>
>> UsePrivilegeSeparation yes
>>
>>
>> it works.
>>
>>
>> Please see the attached ssh -vvv log.
>
> Can you also get an sshd -ddd log from the server side, or at the very
> least look at /var/log/auth.log? The client log is unlikely to be of
> much use in tracking this sort of thing down.
>
> Thanks,
>
--
ᘓ Debian Developer
4096R/ED98D2D344641A6859A0864F1CB4F0F78DECAFE9
Get my key: finger skainz/key@db.debian.org
http://blog.familiekainz.at/static/gpg/8DECAFE9.asc
debug2: load_server_config: filename /etc/ssh/sshd_config
debug2: load_server_config: done config len = 335
debug2: parse_server_config: config /etc/ssh/sshd_config len 335
debug3: /etc/ssh/sshd_config:32 setting PermitRootLogin yes
debug3: /etc/ssh/sshd_config:61 setting ChallengeResponseAuthentication no
debug3: /etc/ssh/sshd_config:84 setting UsePAM yes
debug3: /etc/ssh/sshd_config:89 setting X11Forwarding yes
debug3: /etc/ssh/sshd_config:93 setting PrintMotd no
debug3: /etc/ssh/sshd_config:97 setting UsePrivilegeSeparation yes
debug3: /etc/ssh/sshd_config:113 setting AcceptEnv LANG LC_*
debug3: /etc/ssh/sshd_config:116 setting Subsystem sftp /usr/lib/openssh/sftp-server
debug3: /etc/ssh/sshd_config:124 setting PasswordAuthentication yes
debug1: sshd version OpenSSH_7.4, OpenSSL 1.0.2l 25 May 2017
debug1: private host key #0: ssh-rsa SHA256:8R3rmjx6prPsXuXVjsQjWklRhuFeNq4xCgclpyNDruM
debug1: private host key #1: ecdsa-sha2-nistp256 SHA256:13+rX46/c/biytbW03UJHrRg0XFnftrzRxC+XG/Q9SE
debug1: private host key #2: ssh-ed25519 SHA256:uWSj2/e7z/roKFKrzhx2qFhS1Ru73PE40S22oyzkW5c
debug1: rexec_argv[0]='/usr/sbin/sshd'
debug1: rexec_argv[1]='-p'
debug1: rexec_argv[2]='2222'
debug1: rexec_argv[3]='-dddd'
debug1: rexec_argv[4]='-o'
debug1: rexec_argv[5]='UsePrivilegeSeparation=sandbox'
debug3: oom_adjust_setup
debug1: Set /proc/self/oom_score_adj from 0 to -1000
debug2: fd 3 setting O_NONBLOCK
debug1: Bind to port 2222 on 0.0.0.0.
Server listening on 0.0.0.0 port 2222.
debug2: fd 4 setting O_NONBLOCK
debug3: sock_set_v6only: set socket 4 IPV6_V6ONLY
debug1: Bind to port 2222 on ::.
Server listening on :: port 2222.
debug3: fd 5 is not O_NONBLOCK
debug1: Server will not fork when running in debugging mode.
debug3: send_rexec_state: entering fd = 8 config len 335
debug3: ssh_msg_send: type 0
debug3: send_rexec_state: done
debug1: rexec start in 5 out 5 newsock 5 pipe -1 sock 8
debug1: inetd sockets after dupping: 3, 3
Connection from 129.27.9.27 port 32902 on 37.187.20.171 port 2222
debug1: Client protocol version 2.0; client software version OpenSSH_7.2p2 Debian-5
debug1: match: OpenSSH_7.2p2 Debian-5 pat OpenSSH* compat 0x04000000
debug1: Local version string SSH-2.0-OpenSSH_7.4p1 Debian-10
debug1: Enabling compatibility mode for protocol 2.0
debug2: fd 3 setting O_NONBLOCK
debug3: ssh_sandbox_init: preparing seccomp filter sandbox
debug2: Network child is on pid 29958
debug3: preauth child monitor started
debug3: privsep user:group 106:65534 [preauth]
debug1: permanently_set_uid: 106/65534 [preauth]
debug3: ssh_sandbox_child: setting PR_SET_NO_NEW_PRIVS [preauth]
debug3: ssh_sandbox_child: attaching seccomp filter program [preauth]
debug1: list_hostkey_types: ssh-rsa,rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519 [preauth]
debug3: send packet: type 20 [preauth]
debug1: SSH2_MSG_KEXINIT sent [preauth]
debug3: receive packet: type 20 [preauth]
debug1: SSH2_MSG_KEXINIT received [preauth]
debug2: local server KEXINIT proposal [preauth]
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1 [preauth]
debug2: host key algorithms: ssh-rsa,rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519 [preauth]
debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com [preauth]
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com [preauth]
debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1 [preauth]
debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1 [preauth]
debug2: compression ctos: none,zlib@openssh.com [preauth]
debug2: compression stoc: none,zlib@openssh.com [preauth]
debug2: languages ctos: [preauth]
debug2: languages stoc: [preauth]
debug2: first_kex_follows 0 [preauth]
debug2: reserved 0 [preauth]
debug2: peer client KEXINIT proposal [preauth]
debug2: KEX algorithms: curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,ext-info-c [preauth]
debug2: host key algorithms: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa [preauth]
debug2: ciphers ctos: aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com,aes128-cbc,56-gcm@openssh.com,aes128-cbc, [preauth]
debug2: ciphers stoc: aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com,aes128-cbc,56-gcm@openssh.com,aes128-cbc, [preauth]
debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1 [preauth]
debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1 [preauth]
debug2: compression ctos: none,zlib@openssh.com,zlib [preauth]
debug2: compression stoc: none,zlib@openssh.com,zlib [preauth]
debug2: languages ctos: [preauth]
debug2: languages stoc: [preauth]
debug2: first_kex_follows 0 [preauth]
debug2: reserved 0 [preauth]
debug1: kex: algorithm: curve25519-sha256@libssh.org [preauth]
debug1: kex: host key algorithm: ecdsa-sha2-nistp256 [preauth]
debug1: kex: client->server cipher: aes128-ctr MAC: umac-64-etm@openssh.com compression: none [preauth]
debug1: kex: server->client cipher: aes128-ctr MAC: umac-64-etm@openssh.com compression: none [preauth]
debug1: expecting SSH2_MSG_KEX_ECDH_INIT [preauth]
debug3: receive packet: type 30 [preauth]
debug3: mm_key_sign entering [preauth]
debug3: mm_request_send entering: type 6 [preauth]
debug3: mm_key_sign: waiting for MONITOR_ANS_SIGN [preauth]
debug3: mm_request_receive_expect entering: type 7 [preauth]
debug3: mm_request_receive entering [preauth]
debug3: mm_request_receive entering
debug3: monitor_read: checking request 6
debug3: mm_answer_sign
debug3: mm_answer_sign: hostkey proof signature 0x564d1314a900(100)
debug3: mm_request_send entering: type 7
debug2: monitor_read: 6 used once, disabling now
debug3: send packet: type 31 [preauth]
debug3: send packet: type 21 [preauth]
debug2: set_newkeys: mode 1 [preauth]
debug1: rekey after 4294967296 blocks [preauth]
debug1: SSH2_MSG_NEWKEYS sent [preauth]
debug1: expecting SSH2_MSG_NEWKEYS [preauth]
debug3: send packet: type 7 [preauth]
debug3: receive packet: type 21 [preauth]
debug1: SSH2_MSG_NEWKEYS received [preauth]
debug2: set_newkeys: mode 0 [preauth]
debug1: rekey after 4294967296 blocks [preauth]
debug1: KEX done [preauth]
debug3: receive packet: type 5 [preauth]
debug3: send packet: type 6 [preauth]
debug3: receive packet: type 50 [preauth]
debug1: userauth-request for user skainz service ssh-connection method none [preauth]
debug1: attempt 0 failures 0 [preauth]
debug3: mm_getpwnamallow entering [preauth]
debug3: mm_request_send entering: type 8 [preauth]
debug3: mm_getpwnamallow: waiting for MONITOR_ANS_PWNAM [preauth]
debug3: mm_request_receive_expect entering: type 9 [preauth]
debug3: mm_request_receive entering [preauth]
debug3: mm_request_receive entering
debug3: monitor_read: checking request 8
debug3: mm_answer_pwnamallow
debug2: parse_server_config: config reprocess config len 335
debug3: mm_answer_pwnamallow: sending MONITOR_ANS_PWNAM: 1
debug3: mm_request_send entering: type 9
debug2: monitor_read: 8 used once, disabling now
debug2: input_userauth_request: setting up authctxt for skainz [preauth]
debug3: mm_start_pam entering [preauth]
debug3: mm_request_send entering: type 100 [preauth]
debug3: mm_inform_authserv entering [preauth]
debug3: mm_request_send entering: type 4 [preauth]
debug2: input_userauth_request: try method none [preauth]
debug3: userauth_finish: failure partial=0 next methods="publickey,password" [preauth]
debug3: send packet: type 51 [preauth]
debug3: mm_request_receive entering
debug3: monitor_read: checking request 100
debug1: PAM: initializing for "skainz"
debug1: PAM: setting PAM_RHOST to "129.27.9.27"
debug1: PAM: setting PAM_TTY to "ssh"
debug2: monitor_read: 100 used once, disabling now
debug3: mm_request_receive entering
debug3: monitor_read: checking request 4
debug3: mm_answer_authserv: service=ssh-connection, style=, role=
debug2: monitor_read: 4 used once, disabling now
debug3: receive packet: type 50 [preauth]
debug1: userauth-request for user skainz service ssh-connection method password [preauth]
debug1: attempt 1 failures 0 [preauth]
debug2: input_userauth_request: try method password [preauth]
debug3: mm_auth_password entering [preauth]
debug3: mm_request_send entering: type 12 [preauth]
debug3: mm_auth_password: waiting for MONITOR_ANS_AUTHPASSWORD [preauth]
debug3: mm_request_receive_expect entering: type 13 [preauth]
debug3: mm_request_receive entering [preauth]
debug3: mm_request_receive entering
debug3: monitor_read: checking request 12
debug3: PAM: sshpam_passwd_conv called with 1 messages
debug1: PAM: password authentication accepted for skainz
debug3: mm_answer_authpassword: sending result 1
debug3: mm_request_send entering: type 13
debug3: mm_request_receive_expect entering: type 102
debug3: mm_request_receive entering
debug1: do_pam_account: called
debug3: PAM: do_pam_account pam_acct_mgmt = 0 (Success)
debug3: mm_request_send entering: type 103
Accepted password for skainz from 129.27.9.27 port 32902 ssh2
debug1: monitor_child_preauth: skainz has been authenticated by privileged process
debug3: mm_get_keystate: Waiting for new keys
debug3: mm_request_receive_expect entering: type 26
debug3: mm_request_receive entering
debug1: do_cleanup
debug1: PAM: cleanup
debug3: PAM: sshpam_thread_cleanup entering
debug1: Killing privsep child 29958
debug1: audit_event: unhandled event 12
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