Unable to create home directories

Question

For a school assignment our team has been provided a VM from the school. We were handed the VM with our user accounts added to the sudo group, and I also have access to the "root" and "sysadm" accounts that already exist on the machine, presumably from the sysadmin that did the setup.

I noticed an issue: I am unable to create any directories or files in the home directory.

411blackf16:/> ls -lashr
total 93K
   0 lrwxrwxrwx   1 root   root     29 Sep  8 07:43 vmlinuz.old -> boot/vmlinuz-4.4.0-21-generic
   0 lrwxrwxrwx   1 root   root     29 Sep  8 18:35 vmlinuz -> boot/vmlinuz-4.4.0-36-generic
4.0K drwxr-xr-x  14 root   root   4.0K Sep 12 18:16 var
4.0K drwxr-xr-x  10 root   root   4.0K Sep  8 07:42 usr
4.0K drwxrwxrwt  10 root   root   4.0K Sep 12 18:44 tmp
4.0K drwx------   2 sysadm sysadm 4.0K Sep 12 18:44 sysadm
   0 dr-xr-xr-x  13 root   root      0 Sep 12 18:30 sys
4.0K drwxr-xr-x   2 root   root   4.0K Apr 20 18:08 srv
4.0K drwxr-xr-x   2 root   root   4.0K Apr 19 10:31 snap
 12K drwxr-xr-x   2 root   root    12K Sep 12 13:18 sbin
   0 drwxr-xr-x  36 root   root   1.4K Sep 12 18:32 run
4.0K drwx------   3 root   root   4.0K Sep 12 18:34 root
   0 dr-xr-xr-x 219 root   root      0 Sep  8 23:42 proc
4.0K drwxr-xr-x   2 root   root   4.0K Sep 12 12:20 opt
4.0K drwxr-xr-x   2 root   root   4.0K Apr 20 18:08 mnt
4.0K drwxr-xr-x   4 root   root   4.0K Sep  8 07:42 media
 16K drwx------   2 root   root    16K Sep  8 07:42 lost+found
4.0K drwxr-xr-x   2 root   root   4.0K Sep  8 07:42 lib64
4.0K drwxr-xr-x  22 root   root   4.0K Sep 12 18:22 lib
   0 lrwxrwxrwx   1 root   root     32 Sep  8 07:43 initrd.img.old -> boot/initrd.img-4.4.0-21-generic
   0 lrwxrwxrwx   1 root   root     32 Sep  8 18:35 initrd.img -> boot/initrd.img-4.4.0-36-generic
   0 drwxrwxrwx   2 root   root      0 Sep 12 19:03 home
4.0K drwxr-xr-x 106 root   root   4.0K Sep 12 18:56 etc
   0 drwxr-xr-x  19 root   root   4.2K Sep  8 23:43 dev
1.0K drwxr-xr-x   4 root   root   1.0K Sep 12 13:19 boot
4.0K drwxr-xr-x   2 root   root   4.0K Sep 12 13:18 bin
4.0K drwxr-xr-x  24 root   root   4.0K Sep 12 18:51 ..
4.0K drwxr-xr-x  24 root   root   4.0K Sep 12 18:51 .

The owner is root:root.

411blackf16:/> sudo mkdir /home/test
mkdir: cannot create directory ‘/home/test’: Permission denied
411blackf16:/> sudo su root
root@411blackf16:/# sudo mkdir /home/test
mkdir: cannot create directory ‘/home/test’: Permission denied

Using my sudo user account or the root account still doesn't allow creation of directory or files.

root@411blackf16:/# chmod -R 777 /home/ && touch /home/test
touch: cannot touch '/home/test': Permission denied

Even opening up the permissions doesn't help. Does anyone have some any idea on what is going on here?

Thanks.

Solution

A couple of possibilities:

• /home could be a filesystem which is mounted readonly (the mount command would show you this)
• as an exercise, your instructor could have set some interesting ACL (but then ls should have shown a . or other punctuation character after the permissions)
• the VM (underlying file) permissions are readonly, and the machine cannot write-through its changes (so for instance, journalling might have died).

In a followup, OP showed the results from mount:

411blackf16:/> mount | grep home
ldap:CN=auto.home,OU=Unix Autofs,DC=cs,DC=odu,DC=edu on /home type autofs (rw,relatime,fd=6,pgrp=1415,timeout=300,minproto=5,maxproto=‌​5,indirect) 

and MikeA pointed out that

• the type is "autofs", which shows that the filesystem is mounted, and
• the string "ldap:CN=auto.home,OU=Unix Autofs,DC=cs,DC=odu,DC=edu" indicates that it is mounted using LDAP credentials.
• all of this implies that the actual /home is on another machine that OP cannot modify (aside from files in his/her home-directory).

The root user on the VM would not have any permissions on this filesystem (it would be treated as nobody).

If you want to create local user accounts in the VM, with a local home directory, you can put their home directory in a different location. /home is a very common convention, but not an absolute rule.

Further reading:

• 13.2.7. Configuring Services: autofs

Comments

[Byte Commander]

Can you provide the output of lsattr /home please?

[FantasticSponge]

@ByteCommander lsattr /home provides no output.

[CJ Dana]

have you tried, sudo chown -R $(whoami) /home/

[FantasticSponge]

@CJDana changing ownership or permissions doesn't work. The issue is that /home is mounted without write permissions as part of the school's ldap/non-standard image configuration.

[FantasticSponge]

This is the whole issue....no home directories exist. I should be able to create home directories for users.

[FantasticSponge]

411blackf16:/> mount | grep home ldap:CN=auto.home,OU=Unix Autofs,DC=cs,DC=odu,DC=edu on /home type autofs (rw,relatime,fd=6,pgrp=1415,timeout=300,minproto=5,maxproto=‌​5,indirect)

[Marius]

re @mikea - sure, the point is that either the VM is treating /home as readonly, or the VM cannot write to a supposedly writable filesystem.

[FantasticSponge]

@ThomasDickey Are you able to discern anything from mount output? It appears to be a rw device but this is really outside of my domain and prior knowledge.

[MikeA]

your /home is getting mounted through autofs using a map in ldap. you won't be able to create home directories in /home. they have to be created on some other source and added to the automount map to show up in /home on your vm. you should add the info from your comment to the original post.

[FantasticSponge]

That makes sense. I'll do some looking into how we can revert back to a standard /home configuration.

[FantasticSponge]

@MikeA The thing I don't understand is that I have a home directory I use on the standard machines the school provides but in this case none of the home directories are being included on our VM , although we are using the same ldap authentication to login.

[chrishollinworth]

Upvoted back to 0 for mentioning selinux and because you're new here, but next time pls read the question more carefully

[Gilles 'SO- stop being evil']

@symcbean Please do not give pity upvotes. This disrupts the site by making bad answers (and this one certainly is a bad answer: mostly irrelevant, and the rest is wrong) look ok. You are doing visitors a disservice by making them believe that this answer is useful.

[MikeA]

if you want a local /home instead of automounts, stop and disable the autofs service. then you should be able to create home directories in /home. don't use 777 permissions on /home. if you want to get autofs working, that's a different question you should submit.