ecryptfs-setup-private fails on Fedora

[Jason Xing]

Hi,
i found a problem recently on "ecryptfs-setup-private".

1) If i use Fedora 22(kernel: 4.0 & ecryptfs-utils-108):
a. Using the command #ecryptfs-setup-private, i found "User needs to be a member
of ecryptfs group" on the screen. I checked /etc/group file. I saw that ecryptfs was a group and test(i use "test"as user name) didn't belong to ecryptfs. Thus, i use#gpasswd -a test ecryptfs, adding test to ecryptfs group.
b. Then i use that command #ecryptfs-setup-private again, seeing "Done configuring" on the screen but then something wrong happened.
ecryptfs did generate several files or directories correctly and insert two signature into "$home/.ecryptfs/wrapped-passhrase". Then /sbin/mount.ecryptfs_mount couldn't execute because of permission denied. I checked that file using
#ls -l /sbin/mount.ecryptfs_mount ——> "-rwsr-x---" on the screen. That meant i didn't have the right to access that file. Then using several commands to chmod the file or doing something to avoid failure, i still failed.By the way,i can use
#sudo mount -t ecryptfs [file1] [file2] successfully:)

2) If i use Ubuntu 15.10(kernel: 4.2 & ecryptfs-utils-108):
I checked two files. One is /sbin/mount.ecryptfs_private. The attributes of that file is "-rwsr-x-x". And no ecryptfs group in the /etc/group.

i am trying to use above on different machines, not working successfully on that.

This is about another question: i feel if we use #mount.ecryptfs_private, it would be better that we unlink the key from keyring if we found the same signature listed in the keyring already (checking by using command #keyctl show.).
If i use #keyctl add user <desc> <data> @u artificially, then we couldn't mount again("Invalid argument" on the screen).