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Message #01820
[Bug 732628] Re: TOCTOU in mount.ecryptfs_private
Marc, Kees says that you have looked recently at how FUSE handles
situations like this. Could you offer any suggestions as to how I could
lock the src and dest between the ownership check and the mount/umount?
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https://bugs.launchpad.net/bugs/732628
Title:
TOCTOU in mount.ecryptfs_private
Status in eCryptfs - Enterprise Cryptographic Filesystem:
Triaged
Status in “ecryptfs-utils” package in Ubuntu:
Triaged
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.
References