Commit Graph

94 Commits

Author SHA1 Message Date
Jakob Unterwurzacher
3d6b2685fb Revert "syscallcompat: drop Faccessat AT_SYMLINK_NOFOLLOW helper"
Breaks mounting on MacOS: unix.Faccessat on Darwin does NOT (yet)
support AT_SYMLINK_NOFOLLOW. See d44fe89ba4 .

This reverts commit 0805a63df1.
2019-01-20 13:10:59 +01:00
Jakob Unterwurzacher
0805a63df1 syscallcompat: drop Faccessat AT_SYMLINK_NOFOLLOW helper
unix.Faccessat has added support for AT_SYMLINK_NOFOLLOW in July 2018,
bd9dbc187b (diff-341484dbbe3180cd7a31ef2ad2d679b6)
which means we no longer need our own helper.

Closes https://github.com/rfjakob/gocryptfs/issues/347
2019-01-20 12:59:59 +01:00
Sebastian Lackner
d8bb223dd3 fusefrontend_reverse: Delete leftover debug statement. 2019-01-15 22:07:37 +01:00
Sebastian Lackner
117dc3f2cc fusefrontend_reverse: Fix redeclaration of 'entries' variable.
Go version go1.10.7 linux/amd64 complains with:

 internal/fusefrontend_reverse/rfs.go:333: declaration of "entries" shadows
 declaration at internal/fusefrontend_reverse/rfs.go:327
2019-01-04 20:11:45 +01:00
Jakob Unterwurzacher
6b94f5ef51 reverse mode: -exclude: filter out excluded .name files
Fixes https://github.com/rfjakob/gocryptfs/issues/286 :

While the actual file is properly excluded, the * .name file is still leaked in the directory listing:

```
drwxr-xr-x 2 sebastian sebastian 4,0K Dez 17 14:58 .
drwxr-xr-x 7 sebastian sebastian 4,0K Dez 17 14:45 ..
-r-------- 1 sebastian sebastian  408 Dez 17 14:56 gocryptfs.conf
-r--r--r-- 1 sebastian sebastian   16 Dez 17 14:58 gocryptfs.diriv
-r--r--r-- 1 sebastian sebastian  320 Dez 17 14:58 gocryptfs.longname.3vZ_r3eDPb1_fL3j5VA4rd_bcKWLKT9eaxOVIGK5HFA.name
```
2019-01-04 17:59:00 +01:00
Jakob Unterwurzacher
75a3e2c2ee reverse mode: fix "-exclude" in "-plaintextnames" dir listings
Excluded files showed up in directory listing like this:

 drwxr-xr-x 2 sebastian sebastian 4,0K Dez 17 14:48 .
 drwxr-xr-x 7 sebastian sebastian 4,0K Dez 17 14:45 ..
 -????????? ? ?         ?            ?            ? abcd
 -r-------- 1 sebastian sebastian  366 Dez 17 14:45 gocryptfs.conf

Fixes https://github.com/rfjakob/gocryptfs/issues/285
2019-01-04 17:36:06 +01:00
Jakob Unterwurzacher
930c37e03d syscallcompat: use O_PATH in OpenDirNofollow
This fixes the "0100 directory" problem in reverse mode,
and should be slightly faster.
2018-09-08 18:06:33 +02:00
Jakob Unterwurzacher
9ec9d0c49c syscallcompat: untangle OpenNofollow and rename to OpenDirNofollow
The function used to do two things:

1) Walk the directory tree in a manner safe from symlink attacks
2) Open the final component in the mode requested by the caller

This change drops (2), which was only used once, and lets the caller
handle it. This simplifies the function and makes it fit for reuse in
forward mode in openBackingPath(), and for using O_PATH on Linux.
2018-09-08 17:41:17 +02:00
Jakob Unterwurzacher
7a02f71fc2 fusefrontend_reverse: reject excludes for the root directory ""
This is most likely a mistake by the user. Reject it.
2018-08-15 12:28:29 +02:00
Jakob Unterwurzacher
ec2fdc19cf reverse mode: add --exclude option
https://github.com/rfjakob/gocryptfs/issues/235
2018-08-11 23:26:49 +02:00
Jakob Unterwurzacher
bde7ba57b0 darwin does not have PATH_MAX
Define our own, with the value from Linux.
2018-06-08 00:47:48 +02:00
Jakob Unterwurzacher
719693ec5d fusefrontend[_reverse]: move crypto init up to caller
Both fusefrontend and fusefrontend_reverse were doing
essentially the same thing, move it into main's
initFuseFrontend.

A side-effect is that we have a reference to cryptocore
in main, which will help with wiping the keys on exit
(https://github.com/rfjakob/gocryptfs/issues/211).
2018-02-18 11:21:58 +01:00
Jakob Unterwurzacher
9f8d0d8e57 gccgo: replace syscall.NAME_MAX with unix.NAME_MAX
For some reason the syscall.NAME_MAX constant does not exist
on gccgo, and it does not hurt us to use unix.NAME_MAX instead.

https://github.com/rfjakob/gocryptfs/issues/201
2018-02-01 23:50:11 +01:00
Jakob Unterwurzacher
a2677bce2a fusefrontend_reverse: use OpenNofollow in virtualFile.GetAttr
Makes it robust against symlink races.

Final piece, closes https://github.com/rfjakob/gocryptfs/issues/165
2018-01-17 21:36:38 +01:00
Jakob Unterwurzacher
959e1fc1e2 fusefrontend_reverse: use OpenNofollow in findLongnameParent
Protects findLongnameParent against symlink races.

Also add comments to several functions along the way.

Reported at https://github.com/rfjakob/gocryptfs/issues/165
2018-01-17 20:54:05 +01:00
Jakob Unterwurzacher
36ffd813cd Run go fmt 2018-01-16 23:18:53 +01:00
Sebastian Lackner
631974f9e0 fusefrontend_reverse: Use O_DIRECTORY in OpenDir implementation
Also get rid of the defer - it is not really necessary here.
2017-12-11 21:18:20 +01:00
Sebastian Lackner
96dc2ca709 fusefrontend_reverse: Reject access to device nodes in newFile function
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
2017-12-11 09:55:16 +01:00
Sebastian Lackner
3af51736f3 fusefrontend_reverse: Use openBackingDir in GetAttr
Also fixes 48bd59f388 - the directory FD should
also be closed in case of an error.
2017-12-07 23:36:11 +01:00
Sebastian Lackner
ad0f110191 fusefrontend_reverse: Use openBackingDir in Readlink 2017-12-07 23:36:11 +01:00
Jakob Unterwurzacher
48bd59f388 fusefrontend_reverse: fix fd leak in GetAttr
Fixes https://github.com/rfjakob/gocryptfs/issues/184
2017-12-07 09:01:12 +01:00
Jakob Unterwurzacher
87736eb833 fusefrontend_reverse: secure Access against symlink races (somewhat)
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
2017-12-07 00:11:35 +01:00
Jakob Unterwurzacher
e042eb38fa fusefrontend_reverse: secure Readlink against symlink races
...by using Readlinkat.

Tracking ticket: https://github.com/rfjakob/gocryptfs/issues/165
2017-12-06 21:13:08 +01:00
Jakob Unterwurzacher
a3bdc2bf2b fusefrontend_reverse: secure GetAttr against symlink races
...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
2017-12-06 00:06:31 +01:00
Jakob Unterwurzacher
926cb93b50 fusefrontend_reverse: secure OpenDir against symlink races
...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
2017-12-05 23:14:12 +01:00
Jakob Unterwurzacher
441e796e70 fusefrontend_reverse: secure StatFs agains symlink races
...by ignoring the path that was passed in.

https://github.com/rfjakob/gocryptfs/issues/165
2017-12-02 21:36:07 +01:00
Jakob Unterwurzacher
316b916358 fusefrontend_reverse: secure Open against symlink races
...using the new syscallcompat.OpenNofollow helper.

This change secures Open() against symlink race attacks
as described in https://github.com/rfjakob/gocryptfs/issues/165
2017-12-02 21:07:56 +01:00
Jakob Unterwurzacher
1bb47b6796 reverse: reject too-long symlink target reads with ENAMETOOLONG
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
2017-11-26 21:37:12 +01:00
Sebastian Lackner
90687215a4 fusefrontend_reverse: Do not mix up cache information for different directories
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.
2017-11-25 16:20:48 +01:00
Sebastian Lackner
f80f19f589 fusefrontend_reverse: Add a missing Close() call 2017-11-22 23:42:49 +01:00
Jakob Unterwurzacher
4da245c69d fusefrontend_reverse: fix 176-byte names
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 .
2017-10-01 13:50:25 +02:00
Jakob Unterwurzacher
0c520845f3 main: purge masterkey from memory as soon as possible
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
2017-08-11 19:02:26 +02:00
Jakob Unterwurzacher
75ec94a87a nametransform: add Dir() function
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.
2017-08-06 23:14:39 +02:00
Jakob Unterwurzacher
d12aa57715 fusefronted_reverse: fix ino collision between .name and .diriv files
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
2017-07-29 16:15:49 +02:00
Jakob Unterwurzacher
d5133ca5ac fusefrontend_reverse: return ENOENT for undecryptable names
This was working until DecryptName switched to returning
EBADMSG instead of EINVAL.

Add a test to catch the regression next time.
2017-07-27 20:31:22 +02:00
Charles Duffy
cf1ded5236 Implement force_owner option to display ownership as a specific user. 2017-06-01 00:26:17 +02:00
Jakob Unterwurzacher
9a217ce786 pathiv: move block IV algorithm into this package
This was implemented in fusefrontend_reverse, but we need it
in fusefrontend as well. Move the algorithm into pathiv.BlockIV().
2017-05-30 17:04:46 +02:00
Jakob Unterwurzacher
d202a456f5 pathiv: move derivedIVContainer into the package
...under the new name "FileIVs".

This will also be used by forward mode.
2017-05-30 17:04:46 +02:00
Jakob Unterwurzacher
857507e8b1 fusefrontend_reverse: move pathiv to its own package
We will also need it in forward mode.
2017-05-30 17:04:46 +02:00
Jakob Unterwurzacher
9ecf2d1a3f fusefrontend_reverse: store derived values for hard-linked files
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.
2017-05-25 21:33:16 +02:00
Jakob Unterwurzacher
edb3e19cb5 fix golint complaints 2017-04-29 14:50:58 +02:00
danim7
f1945c4daa Add -forcedecode
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 .
2017-04-23 23:11:56 +02:00
Jakob Unterwurzacher
778c955eea fusefrontend_reverse: switch to stable inode numbers
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
2017-04-01 17:19:15 +02:00
Jakob Unterwurzacher
e87aebb835 fusefrontend_reverse: drop unused dirIVAttr function
This has long been replaced by virtualFile.GetAttr().
2017-04-01 17:05:55 +02:00
Jakob Unterwurzacher
acb73ca436 fusefrontend_reverse: convert fmt.Printf calls to tlog
The fmt.Printfs output would end up in the paniclog.
2017-04-01 15:49:53 +02:00
Jakob Unterwurzacher
3cd18f288f fusefrontend_reverse: add comment to newVirtualFile
...and improve and comment variable naming in findLongnameParent.

No semantic changes.
2017-04-01 14:17:54 +02:00
danim7
fb1b8ced38 fusefrontend_reverse: consistent file owners for .diriv, .name files
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
2017-03-28 22:58:03 +02:00
M. Vefa Bicakci
d48ccb3dda Report correct symbolic link dentry sizes
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.
2017-03-07 20:46:58 +01:00
Jakob Unterwurzacher
445b5019e3 nametransform: fix Raw64 not affecting symlink targets
The symlink functions incorrectly hardcoded the padded
base64 variant.
2017-03-05 22:59:25 +01:00
Jakob Unterwurzacher
5b54577d2e nametransform: fix Raw64 not affecting longnames
HashLongName() incorrectly hardcoded the call to base64.URLEncoding.
2017-03-05 22:25:41 +01:00