9.3p1 Daemon Rejects Client Connections on armv7l-dey-linux-gnueabihf w/ GCC 10/11/12

[Damien Miller]

On Mon, 30 Oct 2023, Grant Erickson wrote:

> I have an NXP i.MX6-based armv7l-dey-linux-gnueabihf system in which I
> am seeing some as-yet-unaccountable behavior in sshd when compiled with
> Arm/GCC 10/11/12. That is, when attempting to scp/slogin/ssh to
> 'root@<host>', where <host> is either a name or IPv4 or IPv6 address,
> the connection is quickly closed by the server without prompting for a
> password.
> 
> The variable I can consistently change across all others to impact
> whether things work or do not work is the toolchain. Under the
> arm-dey-linux-gnueabi-gcc 8.2.0 from Digi Embedded Yocto (DEY),
> scp/slogin/ssh works. Under arm-none-linux-gnueabihf-gcc 10/11/12
> (specifically those from https://developer.arm.com/-/media/Files/downloads/gnu-a/10.3-2021.07/binrel/gcc-arm-10.3-2021.07-x86_64-arm-none-linux-gnueabihf.tar.xz, https://developer.arm.com/-/media/Files/downloads/gnu/11.3.rel1/binrel/arm-gnu-toolchain-11.3.rel1-x86_64-arm-none-linux-gnueabihf.tar.xz, and https://developer.arm.com/-/media/Files/downloads/gnu/12.3.rel1/binrel/arm-gnu-toolchain-12.3.rel1-x86_64-arm-none-linux-gnueabihf.tar.xz) they do not, failing consistently and with the same failure across the three of them.

This might be a syscall sandbox violation. Try building with
SANDBOX_SECCOMP_FILTER_DEBUG defined and see if you get any more information.