[Bug 1052038] [NEW] ecryptfs_fnek_sig missing when login at the same time on cron session close

[Launchpad Bug Tracker]

You have been subscribed to a public bug by Chris J Arges (arges):

when login at the same time on cron session close, ecryptfs directory
will not be decrypted properly.

[IMPACT]
 * folder/file names created by users at the session are unencrypted
 * in desktop session, xdg-user-dirs-gtk-update or other programs creates
   "Desktop", "Download", etc. with unencrypted folder names
   even if encrypted folders with the same name exist.
   On the next login, unencrypted one will be shown with empty content,
   so users feel all data was lost, in spite of actual data is in encrypted one.
 * Reproduced on Oneiric through Quantal

Bug #623708 has quite similar symptom.

[Test Case]
 1. Install ecryptfs-utils and expect
    $ sudo apt-get install ecryptfs-utils expect
 2. Create user 'foo', with encrypted home, and password 'ubuntu'
    $ sudo adduser --encrypt-home foo
 3. Download the lp1052038-test expect script from the bug attachments
 4. In terminal 1, run lp1052038-test in a loop that watches for the eCryptfs encrypted
    filename prefix
    $ false ; while [[ $? -ne 0 ]]; do \
sudo lp1052038-test | grep ECRYPTFS_FNEK_ENCRYPTED ; done
 5. In terminal 2, run a loop that su's from root to user foo. This is the loop that
    will trigger the race condition and cause the loop in terminal 1 to end due to
    encrypted filenames being detected.
    $ while ((1)); do sudo su - foo -c 'sleep 0.1s' ; done

 The expected result is that the loops in terminal 1 and terminal 2 will run forever.
 The buggy result is that the loop in terminal 1 will end with
 ECRYPTFS_FNEK_ENCRYPTED.<remaining encrypted filename> being printed. This typically
 happens within 15 seconds, from my experience.

[Regression Potential]
 The regression potential is that a user cannot properly access his/her encrypted home
 directory. This would be a serious regression and I've done extensive testing on
 Oneiric, Precise, and Quantal to be sure that this will not happen. I've also tested
 the lesser used encrypted ~/Private use case, as well as the use case where filenames
 are not encrypted but the file contents are encrypted.

[Other Info]

 Bug reporter's original reproducer instructions:
 1. setup a home directory encrypted with ecryptfs
 2. set cron job of a user,
    for example, just sleeping for 1 minutes
    /etc/cron.d/ecryptfs-test
    "*/2 *    * * *    user1    sleep 1m"

 3. login at the same time on cron session closed
     for example, login near 00 second in odd minute.
    ==========
    Sep 17 23:32:56 ecryptfs-test login[6019]: pam_ecryptfs: Passphrase file wrapped
    Sep 17 23:33:01 ecryptfs-test CRON[6003]: pam_unix(cron:session): session closed for user user1
    Sep 17 23:33:02 ecryptfs-test login[6012]: pam_unix(login:session): session opened for user user1 by user1(uid=0)
    ==========

Expected results:
 home directory mounted properly

 * mount -l
   /home/user1/.Private on /home/user1 type ecryptfs (ecryptfs_check_dev_ruid,ecryptfs_cipher=aes,ecryptfs_key_bytes=16,ecryptfs_unlink_sigs,ecryptfs_sig=ab224e5125be6655,ecryptfs_fnek_sig=9cb9226b29f1b007)

 * keyctl show
    Session Keyring
           -3 --alswrv   1000    -1  keyring: _uid_ses.1000
    311854780 --alswrv   1000    -1   \_ keyring: _uid.1000
    110408274 --alswrv   1000     0       \_ user: 9cb9226b29f1b007
    923006627 --alswrv   1000     0       \_ user: ab224e5125be6655

Actual results:
 home directory mounted without folder/file names are decrypted

 * mount -l
   /home/user1/.Private on /home/user1 type ecryptfs (ecryptfs_check_dev_ruid,ecryptfs_cipher=aes,ecryptfs_key_bytes=16,ecryptfs_unlink_sigs,ecryptfs_sig=ab224e5125be6655)

 * keyctl show
    Session Keyring
           -3 --alswrv   1000    -1  keyring: _uid_ses.1000
    311854780 --alswrv   1000    -1   \_ keyring: _uid.1000
     71413043 --alswrv   1000     0       \_ user: ab224e5125be6655

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: ecryptfs-utils 96-0ubuntu3
ProcVersionSignature: Ubuntu 3.2.0-30.48-generic 3.2.27
Uname: Linux 3.2.0-30-generic x86_64
ApportVersion: 2.0.1-0ubuntu13
Architecture: amd64
Date: Tue Sep 18 00:21:00 2012
InstallationMedia: Ubuntu 12.04.1 LTS "Precise Pangolin" - Release amd64 (20120823.1)
ProcEnviron:
 TERM=screen-bce
 LANG=ja_JP.UTF-8
 SHELL=/bin/bash
SourcePackage: ecryptfs-utils
UpgradeStatus: No upgrade log present (probably fresh install)

** Affects: ecryptfs
     Importance: Medium
     Assignee: Dustin Kirkland (kirkland)
         Status: In Progress

** Affects: ecryptfs-utils (Ubuntu)
     Importance: Medium
     Assignee: Dustin Kirkland (kirkland)
         Status: Fix Released

** Affects: ecryptfs-utils (Ubuntu Oneiric)
     Importance: Medium
         Status: Fix Committed

** Affects: ecryptfs-utils (Ubuntu Precise)
     Importance: Medium
         Status: Triaged

** Affects: ecryptfs-utils (Ubuntu Quantal)
     Importance: Medium
         Status: Fix Committed


** Tags: amd64 apport-bug precise verification-needed
-- 
ecryptfs_fnek_sig missing when login at the same time on cron session close
https://bugs.launchpad.net/bugs/1052038
You received this bug notification because you are a member of Ubuntu Sponsors Team, which is subscribed to the bug report.