Now that we have Fstatat we can use it in Getdents to
get rid of the path name.
Also, add an emulated version of getdents for MacOS. This allows
to drop the !HaveGetdents special cases from fusefrontend.
Modify the getdents test to test both native getdents and the emulated
version.
Fixes https://github.com/rfjakob/gocryptfs/issues/171
Steps to reproduce:
* Create a regular forward mount point
* Create a new directory in the mount point
* Manually delete the gocryptfs.diriv file from the corresponding ciphertext
directory
* Attempt to delete the directory with 'rmdir <dirname>'
Although the code explicitly checks for empty directories, it will still attempt
to move the non-existent gocryptfs.diriv file and fails with:
rmdir: failed to remove '<dirname>': No such file or directory
MacOS creates lots of these files, and if the directory is otherwise
empty, we would throw an IO error to the unsuspecting user.
With this patch, we log a warning, but otherwise pretend we did not
see it.
Mitigates https://github.com/rfjakob/gocryptfs/issues/140
...and if Getdents is not available at all.
Due to this warning I now know that SSHFS always returns DT_UNKNOWN:
gocryptfs[8129]: Getdents: convertDType: received DT_UNKNOWN, falling back to Lstat
This behavoir is confirmed at http://ahefner.livejournal.com/16875.html:
"With sshfs, I finally found that obscure case. The dtype is always set to DT_UNKNOWN [...]"
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.
This can happen during normal operation when the directory has
been deleted concurrently. But it can also mean that the
gocryptfs.diriv is missing due to an error, so log the event
at "info" level.
unPad16 returns detailed errors including the position of the
incorrect bytes. Kill a possible padding oracle by lumping
everything into a generic error.
The detailed error is only logged if debug is active.
The "!fs.args.DirIV" special case was removed by b17f0465c7
but that, by accident, also removed the handling for
PlaintextNames.
Re-add it as an explicit PlaintextNames special case.
Also adds support for removing directories that miss their
gocryptfs.diriv file for some reason.
tlog is used heavily everywhere and deserves a shorter name.
Renamed using sed magic, without any manual rework:
find * -type f -exec sed -i 's/toggledlog/tlog/g' {} +
Warnings were:
main.go:234: declaration of err shadows declaration at main.go:163:
internal/fusefrontend/file.go:401: declaration of err shadows declaration at internal/fusefrontend/file.go:379:
internal/fusefrontend/file.go:419: declaration of err shadows declaration at internal/fusefrontend/file.go:379:
internal/fusefrontend/fs_dir.go:140: declaration of err shadows declaration at internal/fusefrontend/fs_dir.go:97:
If /proc/self/fd/X did not exist, the actual error is that the file
descriptor was invalid.
go-fuse's pathfs prefers using an open fd even for path-based operations
but does not take any locks to prevent the fd from being closed.
Instead, it retries the operation by path if it get EBADF. So this
change allows the retry logic to work correctly.
This fixes the error
rsync: failed to set times on "/tmp/ping.Kgw.mnt/linux-3.0/[...]/.dvb_demux.c.N7YlEM":
No such file or directory (2)
that was triggered by pingpong-rsync.bash.
Just presenting an empty directory means that the user does not know
that things went wrong unless he checks the syslog or tries to delete
the directory.
It would be nice to report the error even if only some files were
invalid. However, go-fuse does not allow returning the valid
directory entries AND an error.
