This proposal is the counterpart of the modifications from the `-badname`
parameter. It modifies the plain -> cipher mapping for filenames when using
`-badname` parameter. The new function `EncryptAndHashBadName` tries to find a
cipher filename for the given plain name with the following steps:
1. If `badname` is disabled or direct mapping is successful: Map directly
(default and current behaviour)
2. If a file with badname flag has a valid cipher file, this is returned
(=File just ends with the badname flag)
3. If a file with a badname flag exists where only the badname flag was added,
this is returned (=File cipher name could not be decrypted by function
`DecryptName` and just the badname flag was added)
4. Search for all files which cipher file name extists when cropping more and
more characters from the end. If only 1 file is found, return this
5. Return an error otherwise
This allows file access in the file browsers but most important it allows that
you rename files with undecryptable cipher names in the plain directories.
Renaming those files will then generate a proper cipher filename One
backdraft: When mounting the cipher dir with -badname parameter, you can never
create (or rename to) files whose file name ends with the badname file flag
(at the moment this is " GOCRYPTFS_BAD_NAME"). This will cause an error.
I modified the CLI test function to cover additional test cases. Test [Case
7](https://github.com/DerDonut/gocryptfs/blob/badnamecontent/tests/cli/cli_test.go#L712)
cannot be performed since the cli tests are executed in panic mode. The
testing is stopped on error. Since the function`DecryptName` produces internal
errors when hitting non-decryptable file names, this test was omitted.
This implementation is a proposal where I tried to change the minimum amount
of existing code. Another possibility would be instead of creating the new
function `EncryptAndHashBadName` to modify the signature of the existing
function `EncryptAndHashName(name string, iv []byte)` to
`EncryptAndHashName(name string, iv []byte, dirfd int)` and integrate the
functionality into this function directly. You may allow calling with dirfd=-1
or other invalid values an then performing the current functionality.
xfstests generic/523 discovered that we allowed to set
xattrs with "/" in the name, but did not allow to read
them later.
With this change we do not allow to set them in the first
place.
Make `gocryptfs.diriv` and `gocryptfs.xxx.name` files world-readable to make encrypted backups easier
when mounting via fstab.
Having the files follow chmod/chown of their parent does not seem
to be worth the hassle. The content of the diriv files is not
secret, and both diriv and name files are protected by the
perms of the parent dir.
Fixes https://github.com/rfjakob/gocryptfs/issues/539
Retry operations that have been shown to throw EINTR
errors on CIFS.
Todo: Solution for this pain in the back:
warning: unix.Getdents returned errno 2 in the middle of data
rm: cannot remove 'linux-3.0.old3/Documentation/ABI/removed': Input/output error
Progress towards fixing https://github.com/rfjakob/gocryptfs/issues/483 .
Changed invalid file decoding and decryption. Function
DecryptName now shortens the filename until the filename is
decodable and decryptable. Will work with valid **and**
invalid Base64URL delimiter (valid delimiter [0-9a-zA-z_\\-].
If the filename is not decryptable at all, it returns the
original cipher name with flag suffix Changed cli tests to
generate decryptable and undecryptable file names with correct
encrypted content. Replacing #474, extends #393
The comment still mentioned CBC, which has been removed
a long time ago.
The test definition can be rewritten using slice literals,
saving sume stuttering.
This adds support for gitignore-like wildcards and exclude patters in
reverse mode. It (somewhat) fixes#273: no regexp support, but the
syntax should be powerful enough to satisfy most needs.
Also, since adding a lot of --exclude options can be tedious, it adds
the --exclude-from option to read patterns from a file (or files).
Otherwise this can happen, as triggered by xfstests generic/011:
go-fuse: can't convert error type: openat failed: too many open files
The app then gets a misleading "Function not implemented" error.
xfstests generic/083 fills the filesystem almost completely while
running fsstress in parallel. In fsck, these would show up:
readFileID 2580: incomplete file, got 18 instead of 19 bytes
This could happen when writing the file header works, but writing
the actual data fails.
Now we kill the header again by truncating the file to zero.
If the underlying filesystem is full, writing to gocryptfs.diriv may
fail, and later fsck show this:
OpenDir "xyz": could not read gocryptfs.diriv: wanted 16 bytes, got 0
Uncovered by xfstests generic/083.
Also fixes a fd leak in the error path.
Fixes https://github.com/rfjakob/gocryptfs/issues/170
Steps to reproduce the problem:
* Create a regular forward mount point
* Create a file with a shortname and one with a long filename
* Try to run 'mv <shortname> <longname>'
This should actually work and replace the existing file, but instead it
fails with:
mv: cannot move '<shortname>' to '<longname>': File exists
The problem is the creation of the .name file. If the target already exists
we can safely ignore the EEXIST error and just keep the existing .name file.
* extend the diriv cache to 100 entries
* add special handling for the immutable root diriv
The better cache allows to shed some complexity from the path
encryption logic (parent-of-parent check).
Mitigates https://github.com/rfjakob/gocryptfs/issues/127
Dir is like filepath.Dir but returns "" instead of ".".
This was already implemented in fusefrontend_reverse as saneDir().
We will need it in nametransform for the improved diriv caching.
This fixes a few issues I have found reviewing the code:
1) Limit the amount of data ReadLongName() will read. Previously,
you could send gocryptfs into out-of-memory by symlinking
gocryptfs.diriv to /dev/zero.
2) Handle the empty input case in unPad16() by returning an
error. Previously, it would panic with an out-of-bounds array
read. It is unclear to me if this could actually be triggered.
3) Reject empty names after base64-decoding in DecryptName().
An empty name crashes emeCipher.Decrypt().
It is unclear to me if B64.DecodeString() can actually return
a non-error empty result, but let's guard against it anyway.
When a user calls into a deep directory hierarchy, we often
get a sequence like this from the kernel:
LOOKUP a
LOOKUP a/b
LOOKUP a/b/c
LOOKUP a/b/c/d
The diriv cache was not effective for this pattern, because it
was designed for this:
LOOKUP a/a
LOOKUP a/b
LOOKUP a/c
LOOKUP a/d
By also using the cached entry of the grandparent we can avoid lots
of diriv reads.
This benchmark is against a large encrypted directory hosted on NFS:
Before:
$ time ls -R nfs-backed-mount > /dev/null
real 1m35.976s
user 0m0.248s
sys 0m0.281s
After:
$ time ls -R nfs-backed-mount > /dev/null
real 1m3.670s
user 0m0.217s
sys 0m0.403s
