[Bug 718] dropbear does not reliably return exit status to client

[bugzilla-daemon at bugzilla.openmoko.org]

http://bugzilla.openmoko.org/cgi-bin/bugzilla/show_bug.cgi?id=718





------- Additional Comments From hns at computer.org  2007-08-22 16:26 -------
I have now tried on an Acer n30 with Letux Linux. There, it appears to work.

I have also contacted the maintainer of Dropbear (Matt Johnston) and sent him a system call trace 
(strace).

What I noticed: if dropbear runs under control of strace it is quite difficult to get the bug. Only if I write 
the log to a RAM disk.

So it might be a mixture of a race condition bug in Dropbear, processor/kernel speed and I/O activity.


--- how it looks like ---


MacBook-hns:~ hns$ ssh -l root 192.168.0.202 false ; echo $?
root at 192.168.0.202's password:
255
MacBook-hns:~ hns$ ssh -l root 192.168.0.202 true ; echo $?
root at 192.168.0.202's password:
0
MacBook-hns:~ hns$ ssh -l root 192.168.0.202 true ; echo $?
root at 192.168.0.202's password:
255
MacBook-hns:~ hns$ ssh -l root 192.168.0.202 true ; echo $?
root at 192.168.0.202's password:
255
MacBook-hns:~ hns$ 


--- two runs using debug mode - the first is ok, the second one fails ---

MacBook-hns:~ hns$ ssh -vvv -l root 192.168.0.202 true; echo $?
OpenSSH_4.5p1, OpenSSL 0.9.7l 28 Sep 2006
debug1: Reading configuration data /Users/hns/.ssh/config
debug1: Reading configuration data /etc/ssh_config
debug2: ssh_connect: needpriv 0
debug1: Connecting to 192.168.0.202 [192.168.0.202] port 22.
debug1: Connection established.
debug1: identity file /Users/hns/.ssh/identity type -1
debug3: Not a RSA1 key file /Users/hns/.ssh/id_rsa.
debug2: key_type_from_name: unknown key type '-----BEGIN'
debug3: key_read: missing keytype
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug2: key_type_from_name: unknown key type '-----END'
debug3: key_read: missing keytype
debug1: identity file /Users/hns/.ssh/id_rsa type 1
debug1: identity file /Users/hns/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version dropbear_0.49
debug1: no match: dropbear_0.49
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.5
debug2: fd 3 setting O_NONBLOCK
debug1: An invalid name was supplied
Cannot determine realm for numeric host address

debug1: An invalid name was supplied
Cannot determine realm for numeric host address

debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-
sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-
cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc at lysator.liu.se,aes128-
ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-
cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc at lysator.liu.se,aes128-
ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,hmac-ripemd160,hmac-
ripemd160 at openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,hmac-ripemd160,hmac-
ripemd160 at openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,zlib at openssh.com,zlib
debug2: kex_parse_kexinit: none,zlib at openssh.com,zlib
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit: first_kex_follows 0
debug2: kex_parse_kexinit: reserved 0
debug2: kex_parse_kexinit: diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,aes256-cbc,twofish256-cbc,twofish-
cbc,twofish128-cbc,blowfish-cbc
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,aes256-cbc,twofish256-cbc,twofish-
cbc,twofish128-cbc,blowfish-cbc
debug2: kex_parse_kexinit: hmac-sha1-96,hmac-sha1,hmac-md5
debug2: kex_parse_kexinit: hmac-sha1-96,hmac-sha1,hmac-md5
debug2: kex_parse_kexinit: zlib,none
debug2: kex_parse_kexinit: zlib,none
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit: first_kex_follows 0
debug2: kex_parse_kexinit: reserved 0
debug2: mac_init: found hmac-md5
debug1: kex: server->client aes128-cbc hmac-md5 none
debug2: mac_init: found hmac-md5
debug1: kex: client->server aes128-cbc hmac-md5 none
debug2: dh_gen_key: priv key bits set: 129/256
debug2: bits set: 527/1024
debug1: sending SSH2_MSG_KEXDH_INIT
debug1: expecting SSH2_MSG_KEXDH_REPLY
debug3: check_host_in_hostfile: filename /Users/hns/.ssh/known_hosts
debug3: check_host_in_hostfile: match line 7
debug1: Host '192.168.0.202' is known and matches the RSA host key.
debug1: Found key in /Users/hns/.ssh/known_hosts:7
debug2: bits set: 523/1024
debug1: ssh_rsa_verify: signature correct
debug2: kex_derive_keys
debug2: set_newkeys: mode 1
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug2: set_newkeys: mode 0
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /Users/hns/.ssh/identity (0x0)
debug2: key: /Users/hns/.ssh/id_rsa (0x301120)
debug2: key: /Users/hns/.ssh/id_dsa (0x0)
debug1: Authentications that can continue: publickey,password
debug3: start over, passed a different list publickey,password
debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Trying private key: /Users/hns/.ssh/identity
debug3: no such identity: /Users/hns/.ssh/identity
debug1: Offering public key: /Users/hns/.ssh/id_rsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey,password
debug1: Trying private key: /Users/hns/.ssh/id_dsa
debug3: no such identity: /Users/hns/.ssh/id_dsa
debug2: we did not send a packet, disable method
debug3: authmethod_lookup password
debug3: remaining preferred: ,password
debug3: authmethod_is_enabled password
debug1: Next authentication method: password
root at 192.168.0.202's password:
debug3: packet_send2: adding 64 (len 49 padlen 15 extra_pad 64)
debug2: we sent a password packet, wait for reply
debug1: Authentication succeeded (password).
debug1: channel 0: new [client-session]
debug3: ssh_session2_open: channel_new: 0
debug2: channel 0: send open
debug1: Entering interactive session.
debug2: callback start
debug2: client_session2_setup: id 0
debug1: Sending command: true
debug2: channel 0: request exec confirm 0
debug2: fd 3 setting TCP_NODELAY
debug2: callback done
debug2: channel 0: open confirm rwindow 8000 rmax 8000
debug2: channel 0: rcvd eof
debug2: channel 0: output open -> drain
debug2: channel 0: obuf empty
debug2: channel 0: close_write
debug2: channel 0: output drain -> closed

*** note this mesage ***
debug1: client_input_channel_req: channel 0 rtype exit-status reply 0

debug2: channel 0: rcvd close
debug2: channel 0: close_read
debug2: channel 0: input open -> closed
debug3: channel 0: will not send data after close
debug2: channel 0: almost dead
debug2: channel 0: gc: notify user
debug2: channel 0: gc: user detached
debug2: channel 0: send close
debug2: channel 0: is dead
debug2: channel 0: garbage collecting
debug1: channel 0: free: client-session, nchannels 1
debug3: channel 0: status: The following connections are open:
  #0 client-session (t4 r0 i3/0 o3/0 fd -1/-1 cfd -1)

debug3: channel 0: close_fds r -1 w -1 e 6 c -1
debug1: Transferred: stdin 0, stdout 0, stderr 0 bytes in 0.0 seconds
debug1: Bytes per second: stdin 0.0, stdout 0.0, stderr 0.0
debug1: Exit status 0
0
MacBook-hns:~ hns$ ssh -vvv -l root 192.168.0.202 true; echo $?
OpenSSH_4.5p1, OpenSSL 0.9.7l 28 Sep 2006
debug1: Reading configuration data /Users/hns/.ssh/config
debug1: Reading configuration data /etc/ssh_config
debug2: ssh_connect: needpriv 0
debug1: Connecting to 192.168.0.202 [192.168.0.202] port 22.
debug1: Connection established.
debug1: identity file /Users/hns/.ssh/identity type -1
debug3: Not a RSA1 key file /Users/hns/.ssh/id_rsa.
debug2: key_type_from_name: unknown key type '-----BEGIN'
debug3: key_read: missing keytype
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug2: key_type_from_name: unknown key type '-----END'
debug3: key_read: missing keytype
debug1: identity file /Users/hns/.ssh/id_rsa type 1
debug1: identity file /Users/hns/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version dropbear_0.49
debug1: no match: dropbear_0.49
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.5
debug2: fd 3 setting O_NONBLOCK
debug1: An invalid name was supplied
Cannot determine realm for numeric host address

debug1: An invalid name was supplied
Cannot determine realm for numeric host address

debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-
sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-
cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc at lysator.liu.se,aes128-
ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-
cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc at lysator.liu.se,aes128-
ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,hmac-ripemd160,hmac-
ripemd160 at openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,hmac-ripemd160,hmac-
ripemd160 at openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,zlib at openssh.com,zlib
debug2: kex_parse_kexinit: none,zlib at openssh.com,zlib
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit: first_kex_follows 0
debug2: kex_parse_kexinit: reserved 0
debug2: kex_parse_kexinit: diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,aes256-cbc,twofish256-cbc,twofish-
cbc,twofish128-cbc,blowfish-cbc
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,aes256-cbc,twofish256-cbc,twofish-
cbc,twofish128-cbc,blowfish-cbc
debug2: kex_parse_kexinit: hmac-sha1-96,hmac-sha1,hmac-md5
debug2: kex_parse_kexinit: hmac-sha1-96,hmac-sha1,hmac-md5
debug2: kex_parse_kexinit: zlib,none
debug2: kex_parse_kexinit: zlib,none
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit: first_kex_follows 0
debug2: kex_parse_kexinit: reserved 0
debug2: mac_init: found hmac-md5
debug1: kex: server->client aes128-cbc hmac-md5 none
debug2: mac_init: found hmac-md5
debug1: kex: client->server aes128-cbc hmac-md5 none
debug2: dh_gen_key: priv key bits set: 114/256
debug2: bits set: 536/1024
debug1: sending SSH2_MSG_KEXDH_INIT
debug1: expecting SSH2_MSG_KEXDH_REPLY
debug3: check_host_in_hostfile: filename /Users/hns/.ssh/known_hosts
debug3: check_host_in_hostfile: match line 7
debug1: Host '192.168.0.202' is known and matches the RSA host key.
debug1: Found key in /Users/hns/.ssh/known_hosts:7
debug2: bits set: 501/1024
debug1: ssh_rsa_verify: signature correct
debug2: kex_derive_keys
debug2: set_newkeys: mode 1
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug2: set_newkeys: mode 0
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /Users/hns/.ssh/identity (0x0)
debug2: key: /Users/hns/.ssh/id_rsa (0x301120)
debug2: key: /Users/hns/.ssh/id_dsa (0x0)
debug1: Authentications that can continue: publickey,password
debug3: start over, passed a different list publickey,password
debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Trying private key: /Users/hns/.ssh/identity
debug3: no such identity: /Users/hns/.ssh/identity
debug1: Offering public key: /Users/hns/.ssh/id_rsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey,password
debug1: Trying private key: /Users/hns/.ssh/id_dsa
debug3: no such identity: /Users/hns/.ssh/id_dsa
debug2: we did not send a packet, disable method
debug3: authmethod_lookup password
debug3: remaining preferred: ,password
debug3: authmethod_is_enabled password
debug1: Next authentication method: password
root at 192.168.0.202's password:
debug3: packet_send2: adding 64 (len 49 padlen 15 extra_pad 64)
debug2: we sent a password packet, wait for reply
debug1: Authentication succeeded (password).
debug1: channel 0: new [client-session]
debug3: ssh_session2_open: channel_new: 0
debug2: channel 0: send open
debug1: Entering interactive session.
debug2: callback start
debug2: client_session2_setup: id 0
debug1: Sending command: true
debug2: channel 0: request exec confirm 0
debug2: fd 3 setting TCP_NODELAY
debug2: callback done
debug2: channel 0: open confirm rwindow 8000 rmax 8000
debug2: channel 0: rcvd eof
debug2: channel 0: output open -> drain
debug2: channel 0: obuf empty
debug2: channel 0: close_write
debug2: channel 0: output drain -> closed

*** note there is no exit status response mesage! ***

debug2: channel 0: rcvd close
debug2: channel 0: close_read
debug2: channel 0: input open -> closed
debug3: channel 0: will not send data after close
debug2: channel 0: almost dead
debug2: channel 0: gc: notify user
debug2: channel 0: gc: user detached
debug2: channel 0: send close
debug2: channel 0: is dead
debug2: channel 0: garbage collecting
debug1: channel 0: free: client-session, nchannels 1
debug3: channel 0: status: The following connections are open:
  #0 client-session (t4 r0 i3/0 o3/0 fd -1/-1 cfd -1)

debug3: channel 0: close_fds r -1 w -1 e 6 c -1
debug1: Transferred: stdin 0, stdout 0, stderr 0 bytes in 0.1 seconds
debug1: Bytes per second: stdin 0.0, stdout 0.0, stderr 0.0
debug1: Exit status -1
255
MacBook-hns:~ hns$



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