Cannot run suid programs

[amon-ra]

We are trying to run sudo inside the alpine docker image and it fails with:
sudo: effective uid is not 0, is /usr/bin/sudo on a file system with the 'nosuid' option set or an NFS file system without root privileges

This may be related:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=683205

[hurricanehrndz]

The problem is with the registration strings, it is missing the correct flags (POC, needs to be added as suffix) just as @amon-ra mentions. I have verified that if you use the upstream binfmt configuration script that sudo works on emulated CPUs.

[moul]

I just opened a PR (#23) which uses the official script to configure binfmt

[greyltc]

I'm getting this today on version 2.12

[greyltc]

Should this bug be fixed in 2.12?

[alejandro-perez]

I also have this problem. Is there any way we can solve this?

[alejandro-perez]

Appears to be solved with docker run --rm --privileged multiarch/qemu-user-static:register --reset --credential yes

[junaruga]

@amon-ra Could you solve this issue? are you fine to close this ticket?

[junaruga]

Now better alternative. The binfmt_misc files are updated as flags: OCF.

$ uname -m
x86_64

$ docker run --rm --privileged multiarch/qemu-user-static --reset -p yes --credential yes

$ cat /proc/sys/fs/binfmt_misc/qemu-aarch64
enabled
interpreter /usr/bin/qemu-aarch64-static
flags: OCF
offset 0
magic 7f454c460201010000000000000000000200b700
mask ffffffffffffff00fffffffffffffffffeffffff

Then run a Debian aarch64 container arm64v8/debian for testing.

$ docker run --rm -it arm64v8/debian bash

Then below commands work in the container. Though I do not know the warning "/bin/ls: /etc/sudoers: Function not implemented".

# apt-get -y update
# apt-get -y install sudo
# echo "test_user ALL = NOPASSWD: ALL" >> /etc/sudoers
# useradd -m test_user
# su - test_user
$ sudo ls -l /etc/sudoers 
/bin/ls: /etc/sudoers: Function not implemented
-r--r----- 1 root root 699 Aug  6 13:01 /etc/sudoers

I close this ticket. But feel free to reopen if you need something.
Thanks.