SCP in SFTP mode

[Dmitry Belyavskiy]

Hello,

After a deeper investigation I think I can explain what happens.
Special thanks to Jakub Jelen who did the server side investigation.

Red Hat Enterprise Linux 8 series is based on OpenSSH 8.0, which is rather
old.

Soon after the OpenSSH 8.0 was published, the upstream introduced a
server-side fix for sftp, which changes the use of POSIX realpath (on
LInux) to the OpenBSD one with various quirks:
https://github.com/openssh/openssh-portable/commit/569b650f93b561c09c655f83f128e1dfffe74101

If the OpenBSD realpath is in use on the server, the current master
successfully copies directories using scp in SFTP mode. Otherwise problems
occur.

As RHEL 8 series will definitely be in wide use for several more years, I
kindly ask the OpenSSH upstream to consider this patch, which is trying to
workaround the server side on the client side:
https://github.com/openssh/openssh-portable/pull/299
It's a slightly tidied up version of the POC patch I've sent to this ML
before.

Many thanks in advance!


On Fri, Feb 4, 2022 at 11:15 AM Dmitry Belyavskiy <dbelyavs at redhat.com>
wrote:

>
>
> On Fri, Feb 4, 2022 at 7:29 AM Dan Yefihmov <dan at lightwave.net.ru> wrote:
>
>> On February 3, 2022 3:03:25 PM GMT+03:00, Dmitry Belyavskiy <
>> dbelyavs at redhat.com> wrote:
>> >Dear Damien,
>> >
>> >Here is a proof-of-concept patch fixing this issue for me. If it could be
>> >polished, it would be great.
>> >
>> Didn't you forget to free both error message string and ssh buffer in the
>> error path after do_mkdir?
>>
>
> I did, and there are definitely more problems related to this patch. I'll
> try to elaborate a better version.
>
> --
> Dmitry Belyavskiy
>


-- 
Dmitry Belyavskiy