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root permissions issue (reformatted)

Buildroot dan robinson 2 participants 3 messages Dec 14, 2011

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#0 lore raw

I have an NFS mounted root. The directory, on the NFS server, does not have write permissions for 'other'. I am not able to create a file when I run the command, 'touch one'. On the NFS server side, I run 'chmod o+w' and that is shown in the second 'ls' command. I can create a file.

If I 'su' to default, I can create files in that user's directory.

Note that the file, 'one', is owned by 65534. I have included the /etc/passwd file. This is -2 in 16 bits. Noteworthy?

I ran the 'id' command.

# id
uid=0(root) gid=0(root) groups=0(root),10(wheel)

Ideas?

--dan robinson

# ls -al
total 20
drwxrwxr-x    2 root     root          4096 Dec 14  2011 .
drwxr-xr-x   16 root     root          4096 Dec  7  2011 ..
-rw-------    1 65534    65534          104 Dec 14  2011 .ash_history
-rw-r--r--    1 root     root             0 Nov 30  2011 .bash_history
-rw-r--r--    1 root     root           175 Nov 30  2011 .bash_logout
-rw-r--r--    1 root     root           161 Nov 30  2011 .bash_profile
# touch one
touch: one: Permission denied

// chmod o+w has been run on NFS server

# ls -al
total 20
drwxrwxrwx    2 root     root          4096 Dec 14  2011 .
drwxr-xr-x   16 root     root          4096 Dec  7  2011 ..
-rw-------    1 65534    65534          121 Dec 14  2011 .ash_history
-rw-r--r--    1 root     root             0 Nov 30  2011 .bash_history
-rw-r--r--    1 root     root           175 Nov 30  2011 .bash_logout
-rw-r--r--    1 root     root           161 Nov 30  2011 .bash_profile
# touch one
# ls -al
total 20
drwxrwxrwx    2 root     root          4096 Dec 14  2011 .
drwxr-xr-x   16 root     root          4096 Dec  7  2011 ..
-rw-------    1 65534    65534          138 Dec 14  2011 .ash_history
-rw-r--r--    1 root     root             0 Nov 30  2011 .bash_history
-rw-r--r--    1 root     root           175 Nov 30  2011 .bash_logout
-rw-r--r--    1 root     root           161 Nov 30  2011 .bash_profile
-rw-r--r--    1 65534    65534            0 Dec 14  2011 one
# cat /etc/passwd
root::0:0:root:/root:/bin/sh
daemon:x:1:1:daemon:/usr/sbin:/bin/sh
bin:x:2:2:bin:/bin:/bin/sh
sys:x:3:3:sys:/dev:/bin/sh
sync:x:4:100:sync:/bin:/bin/sync
mail:x:8:8:mail:/var/spool/mail:/bin/sh
proxy:x:13:13:proxy:/bin:/bin/sh
www-data:x:33:33:www-data:/var/www:/bin/sh
backup:x:34:34:backup:/var/backups:/bin/sh
operator:x:37:37:Operator:/var:/bin/sh
haldaemon:x:68:68:hald:/:/bin/sh
dbus:x:81:81:dbus:/var/run/dbus:/bin/sh
ftp:x:83:83:ftp:/home/ftp:/bin/sh
nobody:x:99:99:nobody:/home:/bin/sh
sshd:x:103:99:Operator:/var:/bin/sh
default:x:1000:1000:Default non-root user:/home/default:/bin/sh
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#1 lore raw
Quoted 10 lines · dan robinson

I have an NFS mounted root. The directory, on the NFS server, does not have write permissions for 'other'. I am not able to create a file when I run the command, 'touch one'. On the NFS server side, I run 'chmod o+w' and that is shown in the second 'ls' command. I can create a file.

If I 'su' to default, I can create files in that user's directory.

Note that the file, 'one', is owned by 65534. I have included the /etc/passwd file. This is -2 in 16 bits. Noteworthy?

Quoted 7 lines

I ran the 'id' command.

# id
uid=0(root) gid=0(root) groups=0(root),10(wheel)

Ideas?

--dan robinson

Yes, "man exports" and look at the root_squash and no_root_squash option descriptions.
Regards.

#2 lore raw
In reply to dan robinson

Okay, I think I have this figured out. The NFS server is setting the file owner's UID to 65534, which is the user 'nobody' on the server. The NFS client does not have root write permissions on the NFS server's filessytem.

This came out of an investigation into why I couldn't log into a vanilla buildroot built system. Shadow passwords is on, but the root password in the shadow file was blank.

--dan robinson

Quoted 73 lines · dan robinson

I have an NFS mounted root. The directory, on the NFS server, does not have write permissions for 'other'. I am not able to create a file when I run the command, 'touch one'. On the NFS server side, I run 'chmod o+w' and that is shown in the second 'ls' command. I can create a file.

If I 'su' to default, I can create files in that user's directory.

Note that the file, 'one', is owned by 65534. I have included the /etc/passwd file. This is -2 in 16 bits. Noteworthy?

I ran the 'id' command.

# id
uid=0(root) gid=0(root) groups=0(root),10(wheel)

Ideas?

--dan robinson

# ls -al
total 20
drwxrwxr-x    2 root     root          4096 Dec 14  2011 .
drwxr-xr-x   16 root     root          4096 Dec  7  2011 ..
(quoted diff) +0 -4
-rw-------    1 65534    65534          104 Dec 14  2011 .ash_history
-rw-r--r--    1 root     root             0 Nov 30  2011 .bash_history
-rw-r--r--    1 root     root           175 Nov 30  2011 .bash_logout
-rw-r--r--    1 root     root           161 Nov 30  2011 .bash_profile
# touch one
touch: one: Permission denied

// chmod o+w has been run on NFS server

# ls -al
total 20
drwxrwxrwx    2 root     root          4096 Dec 14  2011 .

drwxr-xr-x 16 root root 4096 Dec 7 2011 ..

(quoted diff) +0 -4
-rw-------    1 65534    65534          121 Dec 14  2011 .ash_history
-rw-r--r--    1 root     root             0 Nov 30  2011 .bash_history
-rw-r--r--    1 root     root           175 Nov 30  2011 .bash_logout
-rw-r--r--    1 root     root           161 Nov 30  2011 .bash_profile
# touch one
# ls -al
total 20
drwxrwxrwx    2 root     root          4096 Dec 14  2011 .
drwxr-xr-x   16 root     root          4096 Dec  7  2011 ..
(quoted diff) +0 -5
-rw-------    1 65534    65534          138 Dec 14  2011 .ash_history
-rw-r--r--    1 root     root             0 Nov 30  2011 .bash_history
-rw-r--r--    1 root     root           175 Nov 30  2011 .bash_logout
-rw-r--r--    1 root     root           161 Nov 30  2011 .bash_profile
-rw-r--r--    1 65534    65534            0 Dec 14  2011 one
# cat /etc/passwd
root::0:0:root:/root:/bin/sh
daemon:x:1:1:daemon:/usr/sbin:/bin/sh
bin:x:2:2:bin:/bin:/bin/sh
sys:x:3:3:sys:/dev:/bin/sh
sync:x:4:100:sync:/bin:/bin/sync
mail:x:8:8:mail:/var/spool/mail:/bin/sh
proxy:x:13:13:proxy:/bin:/bin/sh
www-data:x:33:33:www-data:/var/www:/bin/sh
backup:x:34:34:backup:/var/backups:/bin/sh
operator:x:37:37:Operator:/var:/bin/sh
haldaemon:x:68:68:hald:/:/bin/sh
dbus:x:81:81:dbus:/var/run/dbus:/bin/sh
ftp:x:83:83:ftp:/home/ftp:/bin/sh
nobody:x:99:99:nobody:/home:/bin/sh
sshd:x:103:99:Operator:/var:/bin/sh
default:x:1000:1000:Default non-root user:/home/default:/bin/sh
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