[Buildroot] OpenSSH server connection reset

[Peter Korsgaard]

>>>>> "Alex" == Alex Musatti <alex.musatti at gmail.com> writes:

 > Hello everyone,
 > I've recently build firmware image for stm32mp157f-dk2.
 > I noticed sshd server closed the connection during key exchange, so I ran
 > it in debug mode:

 > #/usr/sbin/sshd -ddd -f /etc/ssh/sshd_config

 > debug1: SSH2_MSG_KEXINIT sent [preauth]
 > ssh_sandbox_violation: unexpected system call (arch:0x40000028,syscall:414

So the system call filter detected an unexpected system call. According
to https://marcin.juszkiewicz.com.pl/download/tables/syscalls.html, 414
is ppoll_time64 on ARM. Looking at sandbox-seccomp-filter.c it correctly
allows ppoll_time64 if __NR_ppoll_time64 is defined:

#ifdef __NR_ppoll_time64
        SC_ALLOW(__NR_ppoll_time64),
#endif

What toolchain / C library are you using? It sounds like
__NR_ppoll_time64 is not defined in the kernel headers, but your C
library still uses it at runtime.

Alternatively you can disable the syscall filtering using
BR2_PACKAGE_OPENSSH_SANDBOX.

-- 
Bye, Peter Korsgaard