Age | Commit message (Collapse) | Author |
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Protects findLongnameParent against symlink races.
Also add comments to several functions along the way.
Reported at https://github.com/rfjakob/gocryptfs/issues/165
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Also get rid of the defer - it is not really necessary here.
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Steps to reproduce:
* Create a regular reverse mount point
* Create a file "test" in the original directory
* Access the corresponding encrypted directory in the mount point (ls <encrypted dir>)
* Quickly delete the file in the original data - instead create a device node
* Access the file again, it will access the device node and attempt to read from it
Fixes https://github.com/rfjakob/gocryptfs/issues/187
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Also fixes 48bd59f38843e5ebd4e4c9f666f1aea1c9990803 - the directory FD should
also be closed in case of an error.
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Fixes https://github.com/rfjakob/gocryptfs/issues/184
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Unfortunately, faccessat in Linux ignores AT_SYMLINK_NOFOLLOW,
so this is not completely atomic.
Given that the information you get from access is not very
interesting, it seems good enough.
https://github.com/rfjakob/gocryptfs/issues/165
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...by using Readlinkat.
Tracking ticket: https://github.com/rfjakob/gocryptfs/issues/165
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...by using the OpenNofollow helper & Fstatat.
Also introduce a helper to convert from unix.Stat_t to
syscall.Stat_t.
Tracking ticket: https://github.com/rfjakob/gocryptfs/issues/165
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...by using the new OpenNofollow helper.
The benchmark shows a small but acceptable performance loss:
$ ./benchmark-reverse.bash
LS: 2.182
CAT: 18.221
Tracking ticket: https://github.com/rfjakob/gocryptfs/issues/165
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...by ignoring the path that was passed in.
https://github.com/rfjakob/gocryptfs/issues/165
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...using the new syscallcompat.OpenNofollow helper.
This change secures Open() against symlink race attacks
as described in https://github.com/rfjakob/gocryptfs/issues/165
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If the symlink target gets too long due to base64 encoding, we should
return ENAMETOOLONG instead of having the kernel reject the data and
returning an I/O error to the user.
Fixes https://github.com/rfjakob/gocryptfs/issues/167
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Fixes https://github.com/rfjakob/gocryptfs/issues/168
Steps to reproduce the problem:
* Create a regular reverse mount point
* Create files with the same very long name in multiple directories - so far
everything works as expected, and it will appear with a different name each
time, for example, gocryptfs.longname.A in directory A and
gocryptfs.longname.B in directory B
* Try to access a path with A/gocryptfs.longname.B or B/gocryptfs.longname.A -
this should fail, but it actually works.
The problem is that the longname cache only uses the path as key and not the
dir or divIV. Assume an attacker can directly interact with a reverse mount and
knows the relation longname path -> unencoded path in one directory, it allows
to test if the same unencoded filename appears in any other directory.
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A file with a name of exactly 176 bytes length caused this error:
ls: cannot access ./tmp/dsg/sXSGJLTuZuW1FarwIkJs0w/b6mGjdxIRpaeanTo0rbh0A/QjMRrQZC_4WLhmHI1UOBcA/gocryptfs.longname.QV-UipdDXeUVdl05WruoEzBNPrQCfpu6OzJL0_QnDKY: No such file or directory
ls: cannot access ./tmp/dsg/sXSGJLTuZuW1FarwIkJs0w/b6mGjdxIRpaeanTo0rbh0A/QjMRrQZC_4WLhmHI1UOBcA/gocryptfs.longname.QV-UipdDXeUVdl05WruoEzBNPrQCfpu6OzJL0_QnDKY.name: No such file or directory
-????????? ? ? ? ? ? gocryptfs.longname.QV-UipdDXeUVdl05WruoEzBNPrQCfpu6OzJL0_QnDKY
-????????? ? ? ? ? ? gocryptfs.longname.QV-UipdDXeUVdl05WruoEzBNPrQCfpu6OzJL0_QnDKY.name
Root cause was a wrong shortNameMax constant that failed to
account for the obligatory padding byte.
Fix the constant and also expand the TestLongnameStat test case
to test ALL file name lengths from 1-255 bytes.
Fixes https://github.com/rfjakob/gocryptfs/issues/143 .
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Remove the "Masterkey" field from fusefrontend.Args because it
should not be stored longer than neccessary. Instead pass the
masterkey as a separate argument to the filesystem initializers.
Then overwrite it with zeros immediately so we don't have
to wait for garbage collection.
Note that the crypto implementation still stores at least a
masterkey-derived value, so this change makes it harder, but not
impossible, to extract the encryption keys from memory.
Suggested at https://github.com/rfjakob/gocryptfs/issues/137
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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.
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A directory with a long name has two associated virtual files:
the .name file and the .diriv files.
These used to get the same inode number:
$ ls -di1 * */*
33313535 gocryptfs.longname.2togDFouca9mrTwtfF1RNW5DZRAQY8alaR7wO_Xd5Zw
1000000000033313535 gocryptfs.longname.2togDFouca9mrTwtfF1RNW5DZRAQY8alaR7wO_Xd5Zw/gocryptfs.diriv
1000000000033313535 gocryptfs.longname.2togDFouca9mrTwtfF1RNW5DZRAQY8alaR7wO_Xd5Zw.name
With this change we use another prefix (2 instead of 1) for .name files.
$ ls -di1 * */*
33313535 gocryptfs.longname.2togDFouca9mrTwtfF1RNW5DZRAQY8alaR7wO_Xd5Zw
1000000000033313535 gocryptfs.longname.2togDFouca9mrTwtfF1RNW5DZRAQY8alaR7wO_Xd5Zw/gocryptfs.diriv
2000000000033313535 gocryptfs.longname.2togDFouca9mrTwtfF1RNW5DZRAQY8alaR7wO_Xd5Zw.name
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This was working until DecryptName switched to returning
EBADMSG instead of EINVAL.
Add a test to catch the regression next time.
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This was implemented in fusefrontend_reverse, but we need it
in fusefrontend as well. Move the algorithm into pathiv.BlockIV().
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...under the new name "FileIVs".
This will also be used by forward mode.
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We will also need it in forward mode.
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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.
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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 .
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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
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This has long been replaced by virtualFile.GetAttr().
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The fmt.Printfs output would end up in the paniclog.
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...and improve and comment variable naming in findLongnameParent.
No semantic changes.
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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
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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.
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The symlink functions incorrectly hardcoded the padded
base64 variant.
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HashLongName() incorrectly hardcoded the call to base64.URLEncoding.
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...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.
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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)!
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These were currently passed to decryptPath() were it caused
a warning.
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Speeds up the "ls -lR" benchmark from 2.6 seconds to 2.0.
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This prepares the code for the introduction of a path cache.
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We want all panics to show up in the syslog.
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If there are multiple filesystems backing the gocryptfs filesystems
inode numbers are not guaranteed to be unique.
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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.
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$ 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
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At the moment, in forward mode you can only encrypt paths
and in reverse mode you can only decrypt paths.
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Through base64.RawURLEncoding.
New command-line parameter "-raw64".
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