カテゴリー: Debian

$ uname -r
4.9.0-2-amd64

$ grep CONFIG_EXT4_ENCRYPTION /boot/config-`uname -r`
CONFIG_EXT4_ENCRYPTION=y

$ dpkg-query -W e2fsprogs
e2fsprogs       1.43.4-2

$ sudo dumpe2fs /dev/loop0 | grep -i 'block size'
dumpe2fs 1.43.4 (31-Jan-2017)
Block size:               4096

$ sudo apt install e2fsprogs keyutils util-linux coreutils mount

$ dd if=/dev/zero of=ext4-crypt.img seek=1073741824 bs=1 count=1
1+0 レコード入力
1+0 レコード出力
1 byte copied, 0.000118528 s, 8.4 kB/s

$ /sbin/fdisk ext4-crypt.img

Welcome to fdisk (util-linux 2.29.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Device does not contain a recognized partition table.
Created a new DOS disklabel with disk identifier 0xa25a3988.

Command (m for help): n
Partition type
   p   primary (0 primary, 0 extended, 4 free)
   e   extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1): 
First sector (2048-2097151, default 2048): 
Last sector, +sectors or +size{K,M,G,T,P} (2048-2097151, default 2097151): 

Created a new partition 1 of type 'Linux' and of size 1023 MiB.

Command (m for help): w
The partition table has been altered.
Syncing disks.

$ /sbin/mkfs.ext4 ./ext4-crypt.img 
mke2fs 1.43.4 (31-Jan-2017)
Found a dos partition table in ./ext4-crypt.img
Proceed anyway? (y,N) y
Discarding device blocks: done                            
Creating filesystem with 262144 4k blocks and 65536 inodes
Filesystem UUID: dc44fd43-7d7a-4dfc-87f1-dc52410e2dd1
Superblock backups stored on blocks: 
        32768, 98304, 163840, 229376

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done

$ sudo mount -o loop ./ext4-crypt.img /mnt
$ grep /mnt /etc/mtab 
/dev/loop0 /mnt ext4 rw,relatime,data=ordered 0 0

$ sudo chown `id -u`.`id -g` /mnt
$ ls -la /mnt
合計 36
drwxr-xr-x 3 mk   mk    4096  4月  2 04:58 .
drwxr-xr-x 1 root root   248  3月 28 02:19 ..
drwx------ 2 root root 16384  4月  2 04:58 lost+found

$ sudo tune2fs -O encrypt /dev/loop0
$ sudo dumpe2fs /dev/loop0 | grep -io encrypt
dumpe2fs 1.43.4 (31-Jan-2017)
encrypt

$ /usr/sbin/e4crypt add_key
Enter passphrase (echo disabled): 
Added key with descriptor [07a3ce5a6ebf0396]
$ keyctl show
Session Keyring
1048296028 --alswrv   1000  1000  keyring: _ses
 615559430 --alsw-v   1000  1000   \_ logon: ext4:07a3ce5a6ebf0396

$ mkdir /mnt/encryption
$ /usr/sbin/e4crypt set_policy 07a3ce5a6ebf0396 /mnt/encryption
Key with descriptor [07a3ce5a6ebf0396] applied to /mnt/encryption.

$ /usr/sbin/e4crypt add_key /mnt/encryption

$ echo 'hello' > /mnt/encryption/test.txt
$ ls -la /mnt/encryption
合計 12
drwxr-xr-x 2 mk mk 4096  4月  2 05:07 .
drwxr-xr-x 4 mk mk 4096  4月  2 05:06 ..
-rw-r--r-- 1 mk mk    6  4月  2 05:07 test.txt

$ sudo keyctl clear @s
$ sudo keyctl show
Session Keyring
1048296028 --alswrv   1000  1000  keyring: _ses

$ ls -lA /mnt/encryption
合計 12
-rw-r--r-- 1 mk mk    6  4月  2 05:07 test.txt

$ sudo umount /mnt
$ sudo mount -o loop ./ext4-crypt.img /mnt
$ ls -la /mnt/encryption
合計 12
drwxr-xr-x 2 mk mk 4096  4月  2 05:42 .
drwxr-xr-x 4 mk mk 4096  4月  2 05:06 ..
-rw-r--r-- 1 mk mk    6  4月  2 05:42 uzUlJZQfaxMx,7cC63,53A
$ cat /mnt/encryption/uzUlJZQfaxMx,7cC63,53A 
cat: /mnt/encryption/uzUlJZQfaxMx,7cC63,53A: 要求されたキーが利用できません

$ /usr/sbin/e4crypt add_key /mnt/encryption
Enter passphrase (echo disabled): 
Added key with descriptor [07a3ce5a6ebf0396]
$ ls -la /mnt/encryption
合計 12
drwxr-xr-x 2 mk mk 4096  4月  2 05:42 .
drwxr-xr-x 4 mk mk 4096  4月  2 05:06 ..
-rw-r--r-- 1 mk mk    6  4月  2 05:42 test.txt

$ touch /mnt/1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456
touch: '/mnt/1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456' に touch できません: ファイル名が長すぎます
$ touch /mnt/123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345

$ touch /mnt/encryption/123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345
$ ls -lA /mnt/encryption/
合計 4
-rw-r--r-- 1 mk mk 0  4月  2 07:14 123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345
-rw-r--r-- 1 mk mk 6  4月  2 05:42 test.txt

-rw-r--r-- 1 mk mk    0  4月  2 07:14 _OsoePJvc3qPQCPHbUMtjSynszcHig3BL
-rw-r--r-- 1 mk mk    6  4月  2 05:42 uzUlJZQfaxMx,7cC63,53A

$ mkdir /mnt/encryption2
$ ls -la /mnt/encryption2
合計 8
drwxr-xr-x 2 mk mk 4096  4月  2 06:49 .
drwxr-xr-x 5 mk mk 4096  4月  2 06:49 ..

$ sudo e4crypt add_key /mnt/encryption2
Enter passphrase (echo disabled):
Key with descriptor [9640dd016062b432] already exists
Key with descriptor [9640dd016062b432] applied to /mnt/encryption2.
$ keyctl show
Session Keyring   
1048296028 --alswrv   1000  1000  keyring: _ses
  94779002 --alsw-v      0     0   \_ logon: ext4:69ca01e214957173
 219437542 --alsw-v      0     0   \_ logon: ext4:07a3ce5a6ebf0396
1025344233 --alsw-v      0     0   \_ logon: ext4:9640dd016062b432
$ touch /mnt/encryption2/hoge

$ keyctl clear @s
$ keyctl show
Session Keyring   
1048296028 --alswrv   1000  1000  keyring: _ses
$ sudo umount /mnt
$ sudo mount -o loop ./ext4-crypt.img /mnt

$ sudo e4crypt add_key /mnt/encryption2
Enter passphrase (echo disabled):
Added key with descriptor [9640dd016062b432]
Key with descriptor [9640dd016062b432] applied to /mnt/encryption2.
$ ls -la /mnt/encryption*
/mnt/encryption:  
合計 12
drwxr-xr-x 2 mk mk 4096  4月  2 06:11 .
drwxr-xr-x 5 mk mk 4096  4月  2 06:49 ..
-rw-r--r-- 1 mk mk    0  4月  2 06:11 _OsoePJvc3qPQCPHbUMtjSynszcHig3BL
-rw-r--r-- 1 mk mk    6  4月  2 05:42 uzUlJZQfaxMx,7cC63,53A

/mnt/encryption2: 
合計 8
drwxr-xr-x 2 mk mk 4096  4月  2 06:51 .
drwxr-xr-x 5 mk mk 4096  4月  2 06:49 ..
-rw-r--r-- 1 mk mk    0  4月  2 06:51 hoge

$ ls -lA /mnt/encryption
合計 4
-rw-r--r-- 1 mk mk 0  4月  2 07:14 _OsoePJvc3qPQCPHbUMtjSynszcHig3BL
-rw-r--r-- 1 mk mk 6  4月  2 05:42 uzUlJZQfaxMx,7cC63,53A
mk@x220:~ (1180)$ touch /mnt/encryption/test
touch: '/mnt/encryption/test' のタイムスタンプを設定中です: そのようなファイルやディレクトリはありません
mk@x220:~ (1181)$ ls -lA /mnt/encryption
合計 4
-rw-r--r-- 1 mk mk 0  4月  2 07:14 _OsoePJvc3qPQCPHbUMtjSynszcHig3BL
-rw-r--r-- 1 mk mk 6  4月  2 05:42 uzUlJZQfaxMx,7cC63,53A

$ id
uid=1001(gm) gid=1001(gm) groups=1001(gm),20(dialout),24(cdrom),25(floppy),29(audio),30(dip),44(video),46(plugdev),107(netdev)
$ ls -la /mnt/encryption
合計 12
drwxr-xr-x 2 mk mk 4096  4月  2 06:11 .
drwxr-xr-x 7 mk mk 4096  4月  2 07:48 ..
-rw-r--r-- 1 mk mk    0  4月  2 07:14 _OsoePJvc3qPQCPHbUMtjSynszcHig3BL
-rw-r--r-- 1 mk mk    6  4月  2 05:42 uzUlJZQfaxMx,7cC63,53A
$ ls -la /mnt/encryption
合計 12
drwxrwxrwx 2 mk mk 4096  4月  2 06:11 .
drwxr-xr-x 7 mk mk 4096  4月  2 07:48 ..
-rw-r--r-- 1 mk mk    0  4月  2 07:14 123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345
-rw-r--r-- 1 mk mk    6  4月  2 05:42 test.txt

$ touch /mnt/encryption/other_user
$ ls -lA /mnt/encryption
合計 4
-rw-r--r-- 1 mk mk 0  4月  2 07:14 123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345
-rw-r--r-- 1 gm gm 0  4月  2 07:55 other_user
-rw-r--r-- 1 mk mk 6  4月  2 05:42 test.txt

$ /usr/sbin/e4crypt add_key /mnt/encryption
/mnt/encryption: Permission denied

$ ls -la /mnt/encryption
合計 12
drwxrwxrwx 2 mk mk 4096  4月  2 07:55 .
drwxr-xr-x 7 mk mk 4096  4月  2 07:48 ..
-rw-r--r-- 1 gm gm    0  4月  2 07:55 97NmIBETx,1q9US96etRsA
-rw-r--r-- 1 mk mk    0  4月  2 07:14 _OsoePJvc3qPQCPHbUMtjSynszcHig3BL
-rw-r--r-- 1 mk mk    6  4月  2 05:42 uzUlJZQfaxMx,7cC63,53A
$ /usr/sbin/e4crypt add_key /mnt/encryption
Enter passphrase (echo disabled): 
Added key with descriptor [07a3ce5a6ebf0396]
Error [Permission denied] setting policy.
The key descriptor [07a3ce5a6ebf0396] may not match the existing encryption context for directory [/mnt/encryption].
$ ls -lA /mnt/encryption
合計 4
-rw-r--r-- 1 mk mk 0  4月  2 07:14 123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345
-rw-r--r-- 1 gm gm 0  4月  2 07:55 other_user
-rw-r--r-- 1 mk mk 6  4月  2 05:42 test.txt