SCP in SFTP mode

[Dmitry Belyavskiy]

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