thr3ads.net - openssh bugs - [Bug 1814] New: scp get file prepends -- before filename [Sep 2010]

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bugzilla-daemon at bugzilla.mindrot.org

2010-Sep-03 08:34 UTC

[Bug 1814] New: scp get file prepends -- before filename

https://bugzilla.mindrot.org/show_bug.cgi?id=1814

           Summary: scp get file prepends -- before filename
           Product: Portable OpenSSH
           Version: 5.5p1
          Platform: Other
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: scp
        AssignedTo: unassigned-bugs at mindrot.org
        ReportedBy: srigelsford at googlemail.com


Hi,

First bug file, so bear with me.
I am trying to use openssh scp to retrieve a file from a router.
This works with previous versions of openssh, but for some reason this
version is inserting -- into the command, confusing the router.

The command I am using is:
scp username at IP_address:file_name Destination_file_name

The debug output is:
sam at Laptop:~$ scp -v  sam at router:ns_sys_config config
Executing: program /usr/bin/ssh host router, user sam, command scp -v
-f -- ns_sys_config
OpenSSH_5.5p1 Debian-4ubuntu3, OpenSSL 0.9.8o 01 Jun 2010
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to router [172.16.16.189] port 22.
debug1: Connection established.
debug1: identity file /home/sam/.ssh/id_rsa type -1
debug1: identity file /home/sam/.ssh/id_rsa-cert type -1
debug1: identity file /home/sam/.ssh/id_dsa type -1
debug1: identity file /home/sam/.ssh/id_dsa-cert type -1
debug1: Remote protocol version 2.0, remote software version NetScreen
debug1: no match: NetScreen
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.5p1 Debian-4ubuntu3
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-cbc hmac-sha1 none
debug1: kex: client->server aes128-cbc hmac-sha1 none
debug1: sending SSH2_MSG_KEXDH_INIT
debug1: expecting SSH2_MSG_KEXDH_REPLY
debug1: Host 'vpnfwpr01' is known and matches the DSA host key.
debug1: Found key in /home/sam/.ssh/known_hosts:12
debug1: ssh_dss_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: password
debug1: Next authentication method: password
sam at router's password: 
debug1: Authentication succeeded (password).
debug1: channel 0: new [client-session]
debug1: Entering interactive session.
debug1: Sending environment.
debug1: Sending env LANG = en_GB.utf8
debug1: Sending command: scp -v -f -- ns_sys_config
debug1: client_input_channel_req: channel 0 rtype exit-status reply 0
debug1: channel 0: free: client-session, nchannels 1
debug1: fd 0 clearing O_NONBLOCK
debug1: fd 1 clearing O_NONBLOCK
Transferred: sent 1488, received 1064 bytes, in 0.0 seconds
Bytes per second: sent 30047.3, received 21485.4
debug1: Exit status 1



The router debug shows:
## 2010-09-02 14:18:42 : SSH conn: command = scp -f -- ns_sys_config ##
2010-09-02 14:18:42 : >>>
ssh_2nd_scp_authentication(un='srigelsford',
vsys='Root') ## 2010-09-02 14:18:42 : <<<
ssh_2nd_scp_authentication(aaid=30) = 1 ## 2010-09-02 14:18:42 :
SCP:>>> scp_create_session(command=scp -f -- ns_sys_config) ## 2010-09-0214:18:42 : SCP: <<< scp_create_session() = 0 ## 2010-09-02 14:18:42 :
SSH state trans: SSH_STATE_CONNECTING(9) -> SSH_STATE_DISCONNECTING(11) 


A working version of OpenSSH does the following:
## 2010-09-03 19:33:53 : SSH conn: command = scp -f ns_sys_config ##
2010-09-03 19:33:53 : >>>
ssh_2nd_scp_authentication(un='netscreen',
vsys='Root') ## 2010-09-03 19:33:53 : <<<
ssh_2nd_scp_authentication(aaid=4) = 1 ## 2010-09-03 19:33:53 :
SCP:>>> scp_create_session(command=scp -f ns_sys_config) ## 2010-09-0319:33:53 : SCP: >>> scp_ctx_alloc() ## 2010-09-03 19:33:53 : SCP:
<<<
scp_ctx_alloc() ## 2010-09-03 19:33:53 : SCP: >>>
scp_file_init(fn=ns_sys_config) ## 2010-09-03 19:33:53 : SCP: <<<
scp_file_init(fh=00000000, fs=5566) ## 2010-09-03 19:33:53 : SCP: <<<
scp_create_session() = 1


The issue seems to be the -- between the -f argument and the filename.
I have exhausted my googling abilities to no avail, so guess i might be
one of the first to have this problem.

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bugzilla-daemon at bugzilla.mindrot.org

2010-Sep-05 07:55 UTC

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[Bug 1814] scp get file prepends -- before filename

https://bugzilla.mindrot.org/show_bug.cgi?id=1814

--- Comment #1 from Darren Tucker <dtucker at zip.com.au>  ---
Created attachment 1919
  --> https://bugzilla.mindrot.org/attachment.cgi?id=1919
change triggering the behavior

It was triggered by this change (you can feed it into patch -R to
confirm).  The "--" means the end of the option list to most getopt
implementations (it's specified by SUSv2:
http://www.opengroup.org/onlinepubs/007908799/xsh/getopt.html) and it
means that file names begining with "-" can't be mistaken for
arguments.  I'm not sure if we can do anything about it without
removing that safety.

What kind of router is it?

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bugzilla-daemon at bugzilla.mindrot.org

2010-Sep-06 00:45 UTC

head link

[Bug 1814] scp get file prepends -- before filename

https://bugzilla.mindrot.org/show_bug.cgi?id=1814

Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |djm at mindrot.org

--- Comment #2 from Damien Miller <djm at mindrot.org>  ---
Maybe we could only prepend if the filename list contains an entry that
starts with '-'?

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bugzilla-daemon at bugzilla.mindrot.org

2010-Sep-06 07:11 UTC

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[Bug 1814] scp get file prepends -- before filename

https://bugzilla.mindrot.org/show_bug.cgi?id=1814

--- Comment #3 from Sam <srigelsford at googlemail.com>  ---
(In reply to comment #2)> Maybe we could only prepend if the filename list contains an entry that
> starts with '-'?
Echo the above.
It is a Juniper router (massive enterprise market share, second only to
Cisco).

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bugzilla-daemon at bugzilla.mindrot.org

2010-Sep-06 07:23 UTC

head link

[Bug 1814] scp get file prepends -- before filename

https://bugzilla.mindrot.org/show_bug.cgi?id=1814

Tomas Mraz <t8m at centrum.cz> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |t8m at centrum.cz

--- Comment #4 from Tomas Mraz <t8m at centrum.cz>  ---
But can you really detect it? The command is executed in the remote
shell and there happens potential shell wildcard expansion of the
arguments.

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bugzilla-daemon at bugzilla.mindrot.org

2010-Nov-16 09:16 UTC

head link

[Bug 1814] scp get file prepends -- before filename

https://bugzilla.mindrot.org/show_bug.cgi?id=1814

gmueller at uni-freiburg.de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gmueller at uni-freiburg.de

--- Comment #5 from gmueller at uni-freiburg.de 2010-11-16 20:16:23 EST ---
Our routers (Nortel) don't understand the new syntax, too. They will
refuse sending the file "--". 

ERROR Task=tScp --: S_dosFsLib_FILE_NOT_FOUND

Please implement the old syntax or at least a flag or option to force
the old style command.

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bugzilla-daemon at bugzilla.mindrot.org

2010-Nov-24 01:28 UTC

head link

[Bug 1814] scp get file prepends -- before filename

https://bugzilla.mindrot.org/show_bug.cgi?id=1814

Darren Tucker <dtucker at zip.com.au> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dtucker at zip.com.au

--- Comment #6 from Darren Tucker <dtucker at zip.com.au> 2010-11-24
12:28:08 EST ---
I'll point out that handling of "--" is mandated by POSIX for
getopt
(http://www.opengroup.org/onlinepubs/007908799/xsh/getopt.html).

On the flip side, there's nothing that says an scp implementation must
use getopt (but since there's no spec, nothing says otherwise either).

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bugzilla-daemon at bugzilla.mindrot.org

2010-Dec-06 21:44 UTC

head link

[Bug 1814] scp get file prepends -- before filename

https://bugzilla.mindrot.org/show_bug.cgi?id=1814

petiepooo at yahoo.com <petiepooo at yahoo.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |petiepooo at yahoo.com

--- Comment #7 from petiepooo at yahoo.com <petiepooo at yahoo.com>
2010-12-07 08:44:38 EST ---
It seems like the fix is worse than the danger for this issue. 
Patchset 3682 clearly breaks scp compatibility with a good portion of
the existing (difficult to upgrade) getopt-noncompliant routing
infrastructure in order to prevent a possible vulnerability with names
that start with a dash.  Can anyone point me to an organization that
really uses user, host, or file names that start with a dash?

I didn't think so..  8-)

There's a common expression I've heard about "throwing the baby out
with the bathwater."  It seems that is what is happening here.

At the very least, could you check for existence of a name starting
with a character in the set [-?*] before adding the double-dash?  I
think that would allow non-wildcard copies with getopt-noncompliant
implementations while still giving protection against names starting
with a dash.  Not a perfect solution, but it would at keep
Nortel/Juniper users from having to maintain an out-of-date scp binary.

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bugzilla-daemon at bugzilla.mindrot.org

2011-Jul-11 20:19 UTC

head link

[Bug 1814] scp get file prepends -- before filename

https://bugzilla.mindrot.org/show_bug.cgi?id=1814

markbowen at targusinfo.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |markbowen at targusinfo.com

--- Comment #8 from markbowen at targusinfo.com 2011-07-12 06:19:54 EST ---
This is my first post, so please ALSO bear with me.

I've been working with APC PDU's that don't seem to understand the
--
either ...

The  first example below using Sun_SSH DOES work.
The second example below using Open_SSH does NOT work ...

Unfortunately the PDU's do not produce very verbose logs.

AM I just grasping at straws here??

If indeed this is an Open_SSH bug, is there a work around until it gets
fixed?

Thanks!

--- First Example ---
mfb750 at vista$ /bin/scp -v ticadmin at 192.168.33.193:/config.ini 193.ini
Executing: program /usr/bin/ssh host 192.168.33.193, user ticadmin,
command scp -v -f /config.ini
Sun_SSH_1.1, SSH protocols 1.5/2.0, OpenSSL 0x0090704f
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Rhosts Authentication disabled, originating port will not be
trusted.
debug1: ssh_connect: needpriv 0
debug1: Connecting to 192.168.33.193 [192.168.33.193] port 22.
debug1: Connection established.
debug1: identity file /export/home/mfb750/.ssh/id_rsa type 1
debug1: identity file /export/home/mfb750/.ssh/id_dsa type -1
debug1: Remote protocol version 1.99, remote software version cryptlib
debug1: no match: cryptlib
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-Sun_SSH_1.1
debug1: Failed to acquire GSS-API credentials for any mechanisms (No
credentials were supplied, or the credentials were unavailable or
inaccessible
Unknown code 0
)
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client 3des-cbc hmac-md5 none
debug1: kex: client->server 3des-cbc hmac-md5 none
debug1: Peer sent proposed langtags, ctos:
debug1: Peer sent proposed langtags, stoc:
debug1: We proposed langtags, ctos: i-default
debug1: We proposed langtags, stoc: i-default
debug1: dh_gen_key: priv key bits set: 195/384
debug1: bits set: 489/1024
debug1: sending SSH2_MSG_KEXDH_INIT
debug1: expecting SSH2_MSG_KEXDH_REPLY
debug1: Host '192.168.33.193' is known and matches the RSA host key.
debug1: Found key in /export/home/mfb750/.ssh/known_hosts:25
debug1: bits set: 482/1024
debug1: ssh_rsa_verify: signature correct
debug1: newkeys: mode 1
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: newkeys: mode 0
debug1: SSH2_MSG_NEWKEYS received
debug1: done: ssh_kex2.
debug1: send SSH2_MSG_SERVICE_REQUEST
debug1: got SSH2_MSG_SERVICE_ACCEPT
Authenticated with partial success.
debug1: Authentications that can continue: password
debug1: Next authentication method: password
ticadmin at 192.168.33.193's password:
debug1: Authentication succeeded (password)
debug1: fd 6 setting O_NONBLOCK
debug1: fd 7 setting O_NONBLOCK
debug1: channel 0: new [client-session]
debug1: send channel open 0
debug1: Entering interactive session.
debug1: ssh_session2_setup: id 0
debug1: Sending command: scp -v -f /config.ini
debug1: channel request 0: exec
debug1: channel 0: open confirm rwindow 8192 rmax 1024
config.ini           100% |*****************************| 24605      
00:13
debug1: client_input_channel_req: channel 0 rtype exit-status reply 0
debug1: channel 0: rcvd eof
debug1: channel 0: output open -> drain
debug1: channel 0: obuf empty
debug1: channel 0: close_write
debug1: channel 0: output drain -> closed
debug1: channel 0: rcvd close
debug1: channel 0: close_read
debug1: channel 0: input open -> closed
debug1: channel 0: almost dead
debug1: channel 0: gc: notify user
debug1: channel 0: gc: user detached
debug1: channel 0: send close
debug1: channel 0: is dead
debug1: channel 0: garbage collecting
debug1: channel_free: channel 0: client-session, nchannels 1
debug1: fd 0 clearing O_NONBLOCK
debug1: fd 1 clearing O_NONBLOCK
debug1: Transferred: stdin 0, stdout 0, stderr 0 bytes in 17.5 seconds
debug1: Bytes per second: stdin 0.0, stdout 0.0, stderr 0.0
debug1: Exit status 0
mfb750 at vista$

--- Second Example ---
mfb750 at vista$ scp -v ticadmin at 192.168.33.193:/config.ini 193.ini
Executing: program /usr/local/openssh/5.6/bin/ssh host 192.168.33.193,
user ticadmin, command scp -v -f -- /config.ini
OpenSSH_5.6p1, OpenSSL 1.0.0a 1 Jun 2010
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Connecting to 192.168.33.193 [192.168.33.193] port 22.
debug1: Connection established.
debug1: identity file /export/home/mfb750/.ssh/id_rsa type 1
debug1: identity file /export/home/mfb750/.ssh/id_rsa-cert type -1
debug1: identity file /export/home/mfb750/.ssh/id_dsa type -1
debug1: identity file /export/home/mfb750/.ssh/id_dsa-cert type -1
debug1: Remote protocol version 1.99, remote software version cryptlib
debug1: no match: cryptlib
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.6
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client 3des-cbc hmac-md5 none
debug1: kex: client->server 3des-cbc hmac-md5 none
debug1: sending SSH2_MSG_KEXDH_INIT
debug1: expecting SSH2_MSG_KEXDH_REPLY
debug1: Host '192.168.33.193' is known and matches the RSA host key.
debug1: Found key in /export/home/mfb750/.ssh/known_hosts:25
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
Authenticated with partial success.
debug1: Authentications that can continue: password
debug1: Next authentication method: password
ticadmin at 192.168.33.193's password:
debug1: Authentication succeeded (password).
Authenticated to 192.168.33.193 ([192.168.33.193]:22).
debug1: channel 0: new [client-session]
debug1: Entering interactive session.
debug1: Sending command: scp -v -f -- /config.ini
debug1: client_input_channel_req: channel 0 rtype exit-status reply 0
debug1: channel 0: free: client-session, nchannels 1
debug1: fd 0 clearing O_NONBLOCK
debug1: fd 1 clearing O_NONBLOCK
Transferred: sent 1456, received 872 bytes, in 0.3 seconds
Bytes per second: sent 5807.1, received 3477.9
debug1: Exit status 1
mfb750 at vista$

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bugzilla-daemon at bugzilla.mindrot.org

2011-Jul-13 18:24 UTC

head link

[Bug 1814] scp get file prepends -- before filename

https://bugzilla.mindrot.org/show_bug.cgi?id=1814

--- Comment #9 from petiepooo at yahoo.com <petiepooo at yahoo.com>
2011-07-14 04:24:54 EST ---
Created attachment 2064
  --> https://bugzilla.mindrot.org/attachment.cgi?id=2064
Adds -- only when next argument starts with - or wildcard

Adds a check before adding each "--" getopt flag to command lines. 
Flag is only added if the following argument starts with '-' or
wildcard (* or ?).

My first patch submission, please let me know if I did it wrong.

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bugzilla-daemon at bugzilla.mindrot.org

2012-Mar-09 00:48 UTC

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[Bug 1814] scp get file prepends -- before filename

https://bugzilla.mindrot.org/show_bug.cgi?id=1814

Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Blocks|                            |1930
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED

--- Comment #10 from Damien Miller <djm at mindrot.org> 2012-03-09
11:48:10 EST ---
we have something roughly equivalent in the forthcoming 6.0 release. If
you want to try it out now (rather than waiting a week or two) you can
grab a snapshot from http://www.mindrot.org/openssh_snap

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