chroot("/run/sshd"): Operation not permitted [preauth]

[bbqz007]

it seems that chroot syscall could not success in proot container. i tryed sshd in deployes of centos, fedora, debian and ubuntu. and all caeses failed because of chroot.

root@localhost:~# /usr/sbin/sshd -p 12345 -d
debug1: sshd version OpenSSH_7.4, OpenSSL 1.0.2l 25 May 2017
debug1: private host key #0: ssh-rsa SHA256:axT5qtQVsQmm5xgtN+mOTYkBDavo/D79JDliDA5KOs8 debug1: private host key #1: ecdsa-sha2-nistp256 SHA256:Mkyu/CBWK1lVzwMIll+KJ6KX34TI4DNJ2USDYkH8+qo
debug1: private host key #2: ssh-ed25519 SHA256:J6G8L2C3w9g5HlztYCdFKpG0yvGnxAxXThmXPIQBURo debug1: rexec_argv[0]='/usr/sbin/sshd'
debug1: rexec_argv[1]='-p'
debug1: rexec_argv[2]='12345'
debug1: rexec_argv[3]='-d'
debug1: Bind to port 12345 on 0.0.0.0.
Server listening on 0.0.0.0 port 12345.
debug1: Bind to port 12345 on ::.
Server listening on :: port 12345.
debug1: Server will not fork when running in debugging mode.
debug1: rexec start in 5 out 5 newsock 5 pipe -1 sock 8
debug1: inetd sockets after dupping: 3, 3
Connection from 127.0.0.1 port 43951 on 127.0.0.1 port 12345
debug1: Client protocol version 2.0; client software version OpenSSH_7.7
debug1: match: OpenSSH_7.7 pat OpenSSH* compat 0x04000000
debug1: Local version string SSH-2.0-OpenSSH_7.4p1 Debian-10+deb9u3
debug1: Enabling compatibility mode for protocol 2.0
chroot("/run/sshd"): Operation not permitted [preauth]
debug1: do_cleanup [preauth]
debug1: do_cleanup
debug1: Killing privsep child 23931
debug1: audit_event: unhandled event 12

[alexdcox]

I've experienced this too, unfortunately have nothing to add at the moment other than a +1 but I will post back here if I find a solution...

[michalbednarski]

I've just pushed experimental support for nested chroot() onto nested-chroot branch in case of anybody wants to try. I'll do more tests/wait for feedback and if everything is okay then I'll submit it to Termux apt repo.

[michalbednarski]

Version supporting emulated nested chroot is now available in apt repository. (Run pkg up in Termux to update)