I am unsure if this is related to docker or ubuntu. I got a docker image from coworker and working inside it. I created a container based on the image with volume mapping to host system like docker run -it -v /data/dira:/dira image_from_coworker, and tried to create new directory under /dira using command mkdir /dira/test, but it fails with permission denied message:

# inside the container
I have no name!@7aa44e2d4926:/dirk$ ls -ald /dira
drwxrwxrwx+ 4 root root 4096 Jul 18 23:19 /dira
I have no name!@7aa44e2d4926:/dirk$ mkdir /dira/test
mkdir: cannot create directory '/dira/test': Permission denied
I have no name!@7aa44e2d4926:/dirk$ id
uid=1000 gid=0(root) groups=0(root)

Since /dira has 777 permission, as my best knowledge, anyone can access and write something under the directory. But I couldn’t do. It is so strange. I also noticed there is + symbol at /dira and inspected the ACL, but there looked no special things.

# I checked the ACL from host since the guest doesn't have getfacl command installed.
(base) $ getfacl /data/dira/
# file: data/dira/
# owner: root
# group: root
user::rwx
group::r-x
group:sudo:rwx
mask::rwx
other::rwx
default:user::rwx
default:group::r-x
default:group:sudo:rwx
default:mask::rwx
default:other::r-x

Could anyone help me out with resolving this?

About the host and guest systems.

# host
(base) $ uname -r
6.5.0-35-generic
(base) $ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 22.04.3 LTS
Release:        22.04
Codename:       jammy

# guest
I have no name!@7aa44e2d4926:/dirk$ uname -r
6.5.0-35-generic
I have no name!@7aa44e2d4926:/dirk$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 20.04.5 LTS
Release:        20.04
Codename:       focal

More about the /data: this directory is a hard drive mounted on the host system.

(base) $ df -h
Filesystem                 Size  Used Avail Use% Mounted on
tmpfs                       26G   11M   26G   1% /run
/dev/mapper/vgubuntu-root  1.7T  1.4T  278G  84% /
tmpfs                      126G     0  126G   0% /dev/shm
tmpfs                      5.0M  4.0K  5.0M   1% /run/lock
efivarfs                   128K   31K   93K  25% /sys/firmware/efi/efivars
/dev/nvme0n1p1             511M  6.1M  505M   2% /boot/efi
/dev/sda1                  7.0T  4.9T  1.8T  74% /data
...

Thanks for your concerning!