fuse + encfs, can mount but cannot unmount with fusermount

Question

I created two directories in home, and mounted them with default configurations with encfs.

That worked well enough, the file system is mounted and encrypted fine.

The odd part now is that I cannot unmount it without elevated privileges, with fusermount.

$ fusermount: failed to unmount [path]: Permission denied

Which permission might be needed?

Digging a little, the error seems to be from umount2()

Note, I am not a member of the group 'fuse', but read and write permissions to fusermount has been given to everyone. I do not have root/sudo access.

Answer 1

Next time give us output of your ls -l /bin/fusermount.

Executable /bin/fusermount permissions normally (fusermount version: 2.8.3, on Centos 6.6) are:

$ ls -l /bin/fusermount
-rwsr-x--- 1 root fuse 32336 Dec  7  2011 /bin/fusermount

Which mean you must be root or in the fuse group to execute it.

If you gave the write permission to everyone on the executable /bin/fusermount, that is 100% wrong, because it permits anyone to damage it or replace it with an exploit. Those with execute permission on it (i.e. users in the fuse group) might gain a root shell.

If by ... has been given to everyone you actually gave everyone write permission to the directories inside the mounted filesystem (in attempt to let them unmount), those directory permissions are irrelevant to control of the mount itself via fusermount.