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[segooon <732628@xxxxxxxxxxxxxxxxxx>]

*** This bug is a security vulnerability ***

Private security bug reported:

check_ownerships() function doesn't work as it should because of a race
condition.  Arguments of both mount() and umount() calls can be changed
between the check and the usage.  This may lead to arbitrary mount point
umounting or probably to gaining ability to try passphrases of
otherpeople's ecryptfs storages.

lock_counter() is also racy.  It (1) tries to check existance and
ownership of the file before open(), (2) neither use stat() instead of
lstat() nor O_NOFOLLOW, (3) is not protected against deletion of the
lock file by the owner. The lock file should be probably created in root
only writable directory before dropping EUID.

** Affects: ecryptfs
     Importance: Undecided
         Status: New

** Affects: ecryptfs-utils (Ubuntu)
     Importance: Undecided
         Status: New

** Affects: ecryptfs-utils (Debian)
     Importance: Undecided
         Status: New

** Affects: ecryptfs-utils (Fedora)
     Importance: Undecided
         Status: New

** Also affects: ecryptfs-utils (Ubuntu)
   Importance: Undecided
       Status: New

** Also affects: ecryptfs-utils (Fedora)
   Importance: Undecided
       Status: New

** Also affects: ecryptfs-utils (Debian)
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/732628

Title:
  TOCTOU in mount.ecryptfs_private

Status in eCryptfs - Enterprise Cryptographic Filesystem:
  New
Status in “ecryptfs-utils” package in Ubuntu:
  New
Status in “ecryptfs-utils” package in Debian:
  New
Status in “ecryptfs-utils” package in Fedora:
  New

Bug description:
  check_ownerships() function doesn't work as it should because of a
  race condition.  Arguments of both mount() and umount() calls can be
  changed between the check and the usage.  This may lead to arbitrary
  mount point umounting or probably to gaining ability to try
  passphrases of otherpeople's ecryptfs storages.

  lock_counter() is also racy.  It (1) tries to check existance and
  ownership of the file before open(), (2) neither use stat() instead of
  lstat() nor O_NOFOLLOW, (3) is not protected against deletion of the
  lock file by the owner. The lock file should be probably created in
  root only writable directory before dropping EUID.