SCP in SFTP mode

[Dmitry Belyavskiy]

Dear Damien,

Sorry for being repetitive - but should we consider it to be a known
limitation?

Many thanks in advance!

On Fri, Jan 28, 2022 at 10:53 AM Dmitry Belyavskiy <dbelyavs at redhat.com>
wrote:

> Dear Damien,
>
> On Fri, Jan 28, 2022 at 1:40 AM Damien Miller <djm at mindrot.org> wrote:
>
>> On Thu, 27 Jan 2022, Dmitry Belyavskiy wrote:
>>
>> > Hello,
>> >
>> > When we use scp in sftp mode to copy folder to the machines with the
>> "old"
>> > version of ssh, we get the following error:
>> > ======
>> > $ scp -vvv -r test/ touser at machine:/home/touser
>>
>> What version of OpenSSH are you using? There are a bunch of fixes in git
>> HEAD after 8.8.
>>
>> > If I understand correctly, the failure is caused by the lack of the "
>> > expand-path at openssh.com"
>> > extension to sftp protocol in old releases and (lack of) processing it
>> on
>> > the server side.
>>
>> No, that extension is only invoked when a ~-prefixed path is used.
>>
>> AFAIK this was juat a behaviour difference: scp in sftp mode wasn't
>> creating the destination directory if it didn't exist, whereas legacy
>> scp would do so. It was fixed in the commit you identify below.
>>
>> > For the recent version self-compatibility it was fixed in
>> >
>> https://github.com/openssh/openssh-portable/commit/ac7c9ec894ed0825d04ef69c55babb49bab1d32e
>>
>> -d
>>
>> I've just retested with the recent master
>
> $ ./scp -S `pwd`/ssh -vvv -r -s `pwd`/openbsd-compat/ user at machine:
>
> debug2: subsystem request accepted on channel 0
> ./scp: debug2: Remote version: 3
> ./scp: debug2: Server supports extension "posix-rename at openssh.com"
> revision 1
> ./scp: debug2: Server supports extension "statvfs at openssh.com" revision 2
> ./scp: debug2: Server supports extension "fstatvfs at openssh.com" revision 2
> ./scp: debug2: Server supports extension "hardlink at openssh.com" revision 1
> ./scp: debug2: Server supports extension "fsync at openssh.com" revision 1
> ./scp: debug2: Server supports extension "lsetstat at openssh.com" revision 1
> ./scp: debug2: Sending SSH2_FXP_STAT "/root"
> ./scp: debug3: Sent message fd 6 T:17 I:1
> ./scp: debug3: Received stat reply T:105 I:1 F:0x000f M:40550
> ./scp: debug3: source_sftp: copying local
> /home/dbelyavs/work/upstream/openssh-portable/openbsd-compat to remote
> /root/openbsd-compat
> ./scp: debug2: Sending SSH2_FXP_REALPATH "/root/openbsd-compat"
> ./scp: debug3: Sent message fd 6 T:16 I:2
> ./scp: realpath /root/openbsd-compat: No such file
> ./scp: upload "/root/openbsd-compat": path canonicalization failed
> ./scp: failed to upload directory
> /home/dbelyavs/work/upstream/openssh-portable/openbsd-compat to
> /root/openbsd-compat
>
> The failure occurs even when I specify absolute paths on the
> source/destination machine.
>
> The destination machine has OpenSSH_8.0p1 with patches.
>
> --
> Dmitry Belyavskiy
>


-- 
Dmitry Belyavskiy