Hi, original designer/author of eCryptfs chiming in. Sorry for the mess
with file name lengths, but because of technical constraints in the
kernel file system stack and security concerns, I went with the design I
did.

Good news is, I fixed this issue for file-based encryption by designing
it (sort of) right in file system native encryption. That's currently
available in ext4 for kernels 4.1 and later. We're working to switch
from eCryptfs to ext4 encryption for Ubuntu 17.10.

https://github.com/google/fscrypt/issues/24

We've released a really great user space utility to help you do pretty
much everything you can do with eCryptfs today:

https://github.com/google/fscrypt

https://launchpad.net/~ubuntu-security/+archive/ubuntu/ubuntu-security-
staging/+build/13255257

Prior to Ubuntu 17.10, you'll be in "early adopter" territory with ext4
encryption on Ubuntu.

Note that I did make a security tradeoff with the current version of
file name encryption in ext4 for the sake of giving you (1) the full 255
characters and (2) decent performance. If the plaintext prefixes for two
file names in the same directory collide, then the ciphertext prefixes
will also collide. I asked Alex Cope and Eric Biggers to try to fix that
by implementing a new encryption mode that they proposed upstream, but
getting new encryption modes upstream isn't necessarily a trivial
prospect. No real crypto review/comments so far.

https://www.spinics.net/lists/linux-crypto/msg22416.html

Note that Android is carrying the HEH patches and is using that mode for
file name encryption. Hopefully we'll be able to get that upstream at
some point.

** Bug watch added: github.com/google/fscrypt/issues #24
   https://github.com/google/fscrypt/issues/24

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https://bugs.launchpad.net/bugs/344878

Title:
  file name too long when creating new file (ecryptfs_lookup:
  lookup_one_len() returned [-36] on lower_dentry)

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