We use two levels of buffers:
1) 4kiB+overhead for each ciphertext block
2) 128kiB+overhead for each FUSE write (32 ciphertext blocks)
This commit adds a sync.Pool for both levels.
The memory-efficiency for small writes could be improved,
as we now always use a 128kiB buffer.
128kiB = 32 x 4kiB pages is the maximum we get from the kernel. Splitting
up smaller writes is probably not worth it.
Parallelism is limited to two for now.
Spawn a worker goroutine that reads the next 512-byte block
while the current one is being drained.
This should help reduce waiting times when /dev/urandom is very
slow (like on Linux 3.16 kernels).
On my machine, reading 512-byte blocks from /dev/urandom
(same via getentropy syscall) is a lot faster in terms of
throughput:
Blocksize Throughput
16 28.18 MB/s
512 83.75 MB/s
For a single-threaded streaming write, this drops the CPU usage of
nonceGenerator.Get to almost 1/3:
flat flat% sum% cum cum%
Before 0 0% 95.08% 0.35s 2.92% github.com/rfjakob/gocryptfs/internal/cryptocore.(*nonceGenerator).Get
After 0.01s 0.092% 92.34% 0.13s 1.20% github.com/rfjakob/gocryptfs/internal/cryptocore.(*nonceGenerator).Get
This change makes the nonce reading single-threaded, which may
hurt massively-parallel writes.
This check would need locking to be multithreading-safe.
But as it is in the fastpath, just remove it.
rand.Read() already guarantees that the value is random.
Travis failed on Go 1.6.3 with this error:
internal/pathiv/pathiv_test.go:20: no args in Error call
This change should solve the problem and provides a better error
message on (real) test failure.
With hard links, the path to a file is not unique. This means
that the ciphertext data depends on the path that is used to access
the files.
Fix that by storing the derived values when we encounter a hard-linked
file. This means that the first path wins.
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
This commit defines all exit codes in one place in the exitcodes
package.
Also, it adds a test to verify the exit code on incorrect
password, which is what SiriKali cares about the most.
Fixes https://github.com/rfjakob/gocryptfs/issues/77 .
Misspell Finds commonly misspelled English words
gocryptfs/internal/configfile/scrypt.go
Line 41: warning: "paramter" is a misspelling of "parameter" (misspell)
gocryptfs/internal/ctlsock/ctlsock_serve.go
Line 1: warning: "implementes" is a misspelling of "implements" (misspell)
gocryptfs/tests/test_helpers/helpers.go
Line 27: warning: "compatability" is a misspelling of "compatibility" (misspell)
This can happen during normal operation, and is harmless since
14038a1644
"fusefrontend: readFileID: reject files that consist only of a header"
causes dormant header-only files to be rewritten on the next write.
We do not have to track the writeOnly status because the kernel
will not forward read requests on a write-only FD to us anyway.
I have verified this behavoir manually on a 4.10.8 kernel and also
added a testcase.
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
