As reported at https://github.com/rfjakob/gocryptfs/issues/105 ,
the "ioutil.WriteFile(file, iv, 0400)" call causes "permissions denied"
errors on an NFSv4 setup.
"strace"ing diriv creation and gocryptfs.conf creation shows this:
conf (works on the user's NFSv4 mount):
openat(AT_FDCWD, "/tmp/a/gocryptfs.conf.tmp", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0400) = 3
diriv (fails):
openat(AT_FDCWD, "/tmp/a/gocryptfs.diriv", O_WRONLY|O_CREAT|O_TRUNC|O_CLOEXEC, 0400) = 3
This patch creates the diriv file with the same flags that are used for
creating the conf:
openat(AT_FDCWD, "/tmp/a/gocryptfs.diriv", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0400) = 3
Closes https://github.com/rfjakob/gocryptfs/issues/105
Force decode of encrypted files even if the integrity check fails, instead of
failing with an IO error. Warning messages are still printed to syslog if corrupted
files are encountered.
It can be useful to recover files from disks with bad sectors or other corrupted
media.
Closes https://github.com/rfjakob/gocryptfs/pull/102 .
go-fuse has added a new method to the nodefs.File interface that
caused this build error:
internal/fusefrontend/file.go:75: cannot use file literal (type *file) as type nodefs.File in return argument:
*file does not implement nodefs.File (missing Flock method)
Fixes https://github.com/rfjakob/gocryptfs/issues/104 and
prevents the problem from happening again.
The volatile inode numbers that we used before cause "find" to complain and error out.
Virtual inode numbers are derived from their parent file inode number by adding 10^19,
which is hopefully large enough no never cause problems in practice.
If the backing directory contains inode numbers higher than that, stat() on these files
will return EOVERFLOW.
Example directory lising after this change:
$ ls -i
926473 gocryptfs.conf
1000000000000926466 gocryptfs.diriv
944878 gocryptfs.longname.hmZojMqC6ns47eyVxLlH2ailKjN9bxfosi3C-FR8mjA
1000000000000944878 gocryptfs.longname.hmZojMqC6ns47eyVxLlH2ailKjN9bxfosi3C-FR8mjA.name
934408 Tdfbf02CKsTaGVYnAsSypA
This PR addresses the Issue #95, about "Confusing file owner for
longname files in reverse mode".
It affects only the reverse mode, and introduces two
modifications:
1) The "gocryptfs.longname.XXXX.name" files are assigned the owner and
group of the underlying plaintext file. Therefore it is consistent
with the file "gocryptfs.longname.XXXX" that has the encrypted
contents of the plaintext file.
2) The two virtual files mentioned above are given -r--r--r--
permissions. This is consistent with the behavior described in
function Access in internal/fusefrontend_reverse/rfs.go where all
virtual files are always readable. Behavior also observed in point
c) in #95 .
Issue #95 URL: https://github.com/rfjakob/gocryptfs/issues/95
Pull request URL: https://github.com/rfjakob/gocryptfs/pull/97
Due to kernel readahead, we usually get multiple read requests
at the same time. These get submitted to the backing storage in
random order, which is a problem if seeking is very expensive.
Details: https://github.com/rfjakob/gocryptfs/issues/92
...if doWrite() can do it for us. This avoids the situation
that the file only consists of a file header when calling
doWrite.
A later patch will check for this condition and warn about it,
as with this change it should no longer occour in normal operation.
If you truncate a ciphertext file to 19 bytes, you could get the
impression that the plaintext is 18446744073709551585 bytes long,
as reported by "ls -l".
Fix it by clamping the value to zero.
Prior to this commit, gocryptfs's reverse mode did not report correct
directory entry sizes for symbolic links, where the dentry size needs to
be the same as the length of a string containing the target path.
This commit corrects this issue and adds a test case to verify the
correctness of the implementation.
This issue was discovered during the use of a strict file copying program
on a reverse-mounted gocryptfs file system.
Raw64 is supported (but was disabled by default) since gocryptfs
v1.2. However, the implementation was buggy because it forgot
about long names and symlinks.
Disable it for now by default and enable it later, together
with HKDF.
...but keep it disabled by default for new filesystems.
We are still missing an example filesystem and CLI arguments
to explicitely enable and disable it.
As we have dropped Go 1.4 compatibility already, and will add
a new feature flag for gocryptfs v1.3 anyway, this is a good
time to enable Raw64 as well.
There is no security reason for doing this, but it will allow
to consolidate the code once we drop compatibility with gocryptfs v1.2
(and earlier) filesystems.
There are two independent backends, one for name encryption,
the other one, AEAD, for file content.
"BackendTypeEnum" only applies to AEAD (file content), so make that
clear in the name.
Version 1.1 of the EME package (github.com/rfjakob/eme) added
a more convenient interface. Use it.
Note that you have to upgrade your EME package (go get -u)!
This really only handles scrypt and no other key-derivation functions.
Renaming the files prevents confusion once we introduce HKDF.
renamed: internal/configfile/kdf.go -> internal/configfile/scrypt.go
renamed: internal/configfile/kdf_test.go -> internal/configfile/scrypt_test.go
A crypto benchmark mode like "openssl speed".
Example run:
$ ./gocryptfs -speed
AES-GCM-256-OpenSSL 180.89 MB/s (selected in auto mode)
AES-GCM-256-Go 48.19 MB/s
AES-SIV-512-Go 37.40 MB/s
This used to hang at 100% CPU:
cat /dev/zero | gocryptfs -init a
...and would ultimately send the box into out-of-memory.
The number 1000 is chosen arbitrarily and seems big enough
given that the password must be one line.
Suggested by @mhogomchungu in https://github.com/rfjakob/gocryptfs/issues/77 .
From the comment:
// CheckTrailingGarbage tries to read one byte from stdin and exits with a
// fatal error if the read returns any data.
// This is meant to be called after reading the password, when there is no more
// data expected. This helps to catch problems with third-party tools that
// interface with gocryptfs.
Preallocation is very slow on hdds that run btrfs. Give the
user the option to disable it. This greatly speeds up small file
operations but reduces the robustness against out-of-space errors.
Also add the option to the man page.
More info: https://github.com/rfjakob/gocryptfs/issues/63
This could have caused spurious ENOENT errors.
That it did not cause these errors all the time is interesting
and probably because an earlier readdir would place the entry
in the cache. This masks the bug.
$ golint ./... | grep -v underscore | grep -v ALL_CAPS
internal/fusefrontend_reverse/rfs.go:52:36: exported func NewFS returns unexported type *fusefrontend_reverse.reverseFS, which can be annoying to use
internal/nametransform/raw64_go1.5.go:10:2: exported const HaveRaw64 should have comment (or a comment on this block) or be unexported
The Back In Time backup tool (https://github.com/bit-team/backintime)
wants to write directly into the ciphertext dir.
This may cause the cached directory IV to become out-of-date.
Having an expiry time limits the inconstency to one second, like
attr_timeout does for the kernel getattr cache.
Running xfstests generic/075 on tmpfs often triggered a panic
for what seems to be a tmpfs bug.
Quoting from the email to lkml,
http://www.spinics.net/lists/kernel/msg2370127.html :
tmpfs seems to be incorrectly returning 0-bytes when reading from
a file that is concurrently being truncated.
Stat() calls are expensive on NFS as they need a full network
round-trip. We detect when a write immediately follows the
last one and skip the Stat in this case because the write
cannot create a file hole.
On my (slow) NAS, this takes the write speed from 24MB/s to
41MB/s.
Test that we get the right timestamp when extracting a tarball.
Also simplify the workaround in doTestUtimesNano() and fix the
fact that it was running no test at all.
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.
AES-SIV uses 1/2 of the key for authentication, 1/2 for
encryption, so we need a 64-byte key for AES-256. Derive
it from the master key by hashing it with SHA-512.
On a CPU without AES-NI:
$ go test -bench .
Benchmark4kEncStupidGCM-2 50000 24155 ns/op 169.57 MB/s
Benchmark4kEncGoGCM-2 20000 93965 ns/op 43.59 MB/s
Benchmark4kEncGCMSIV-2 500 2576193 ns/op 1.59 MB/s
The last patch added functionality for generating gocryptfs.longname.*
files, this patch adds support for mapping them back to the full
filenames.
Note that resolving a long name needs a full readdir. A cache
will be implemented later on to improve performance.
As ReadDirIV operates on a path anyway, opening the directory
has no clear safety advantage w.r.t. concurrent renames.
If the backing directory is a reverse-mounted gocryptfs filesystem,
each directory open is an OPENDIR, and this causes a full directory
read!
This patch improves the "ls -lR" performance of an
DIR --> gocryptfs-reverse --> gocryptfs
chain by a factor of ~10.
OPENDIR counts for ls -lR:
Before 15570
After 2745
