Commit Graph

1086 Commits

Author SHA1 Message Date
Jakob Unterwurzacher
03bf604fc0 syscallcompat: OpenNofollow: use O_DIRECTORY flag
...when opening intermedia directories to give us an
extra layer of safety.

From the FreeBSD man page:

     This flag can be used to prevent applications with elevated
     privileges from opening files which are even unsafe to open with O_RDONLY,
     such as device nodes.
2017-12-05 23:31:07 +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
e604ce6dea syscallcompat: OpenNofollow: fix relPath="" case
Sometimes want to open baseDir itself. This case
was broken, fix it.
2017-12-05 23:08:55 +01:00
Jakob Unterwurzacher
47b13e0a8d Documentation: Add reverse mode benchmark results 2017-12-05 22:54:08 +01:00
Jakob Unterwurzacher
70bcf58a9b syscallcompat: convert Getdents to fd input, add emulation
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.
2017-12-03 19:33:26 +01:00
Jakob Unterwurzacher
e33593d30d syscallcompat: add Fstatat + emulation + test
Fstatat has recently been added to x/sys/unix. Make
it available for use in gocryptfs.
2017-12-03 19:32:59 +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
91e042e2ba syscallcompat: add OpenNofollow helper
OpenNofollow = symlink-race-safe Open

Prepares fixing https://github.com/rfjakob/gocryptfs/issues/165
2017-12-02 20:35:44 +01:00
Jakob Unterwurzacher
1d28973611 syscallcompat: move test setup into its own file
The infrastructure will also be used by the upcoming
OpenNofollow tests.
2017-12-02 19:57:23 +01:00
Jakob Unterwurzacher
77191c3485 syscallcompat: use Unlinkat and Symlinkat from x/sys/unix
I'm unsure why I did not notice this earlier, but the
syscall wrappers provided by x/sys/unix seem to do just
fine.

Drop our own version.
2017-12-02 18:36:18 +01:00
Sebastian Lackner
616a468180 syscallcompat: Improve the Openat and Mknodat syscall emulation
This avoids the conversion to an absolute path.
2017-12-01 09:41:52 +01:00
Sebastian Lackner
f30522a0c1 syscallcompat: Fix syscall emulation for absolute paths
For absolute paths, the file descriptor should be ignored. In such a case
there is also no need to hold the lock or change the working directory.
2017-12-01 09:41:52 +01:00
Sebastian Lackner
9bcde0c09e fusefrontend: Improve documentation of mkdirWithIv and WriteDirIV
As requested in https://github.com/rfjakob/gocryptfs/pull/179
2017-12-01 09:41:52 +01:00
Jakob Unterwurzacher
e97c23e083 syscallcompat: check that we get NOFOLLOW wherever possible
...and fix the instances where the AT_SYMLINK_NOFOLLOW /
O_NOFOLLOW / O_EXCL flag was missing.
2017-11-30 19:40:53 +01:00
Jakob Unterwurzacher
22282aefe6 syscallcompat: add tests for emulated syscalls
Also fix the bug in emulateFchmodat that was found by the tests.
2017-11-30 19:10:21 +01:00
Jakob Unterwurzacher
bd79a8cd0d syscallcompat: build emulated syscalls under linux, too
This will allow to test them under linux as well.
2017-11-30 17:07:55 +01:00
Sebastian Lackner
614745ee57 fusefrontend: allow_other: close race between mkdir and chown
Fixes the same problem as described in 72b975867a,
except for directories instead of device nodes.
2017-11-29 13:28:04 +01:00
Sebastian Lackner
67bcbe81e8 fusefrontend: Use Fchownat to implement Chown 2017-11-29 13:05:46 +01:00
Sebastian Lackner
0162392a28 fusefrontend: Use Fchmodat to implement Chmod 2017-11-29 12:55:41 +01:00
Sebastian Lackner
0f44c617d0 syscallcompat: Introduce unlinkat syscall with flags argument 2017-11-29 12:41:23 +01:00
Sebastian Lackner
5d44a31b41 fusefrontend: Use openBackingPath in Unlink and simplify code 2017-11-28 09:28:06 +01:00
Sebastian Lackner
2591900b69 fusefrontend: Handle PlaintextNames mode in Unlink
In PlaintextNames mode the "gocryptfs.longname." prefix does not have any
special meaning. We should not attempt to delete any .name files.

Partially fixes https://github.com/rfjakob/gocryptfs/issues/174
2017-11-28 09:28:06 +01:00
Sebastian Lackner
eba49402e4 fusefrontend: Introduce a openBackingPath helper and use it to simplify Mknod and Symlink 2017-11-28 09:28:06 +01:00
Sebastian Lackner
ad2720e0f9 fusefrontend: allow_other: close race between symlink and chown
Fixes the same problem as described in 72b975867a,
except for symlinks instead of device nodes.
2017-11-28 09:28:06 +01:00
Sebastian Lackner
5a56810603 fusefrontend: Use the Symlinkat syscall for longname handling 2017-11-28 09:28:06 +01:00
Sebastian Lackner
295c4c2b85 fusefrontend: Set owner after symlink creation in PlaintextNames mode
This is already done in regular mode, but was missing when PlaintextNames mode
is enabled. As a result, symlinks created by non-root users were still owned
by root afterwards.

Fixes https://github.com/rfjakob/gocryptfs/issues/176
2017-11-28 09:28:06 +01:00
Sebastian Lackner
3f68b0c09a fusefrontend: Handle PlaintextNames mode in Mknod
In PlaintextNames mode the "gocryptfs.longname." prefix does not have any
special meaning. We should not attempt to read the directory IV or to
create special .name files.

Partially fixes https://github.com/rfjakob/gocryptfs/issues/174
2017-11-28 09:28:06 +01:00
Sebastian Lackner
8c5069c637 syscallcompat: Fix Fchownat syscall wrapper on darwin
* Acquire the lock before reading the current directory
* Fix a file descriptor leak
2017-11-28 09:28:06 +01:00
Jakob Unterwurzacher
72b975867a fusefronted: allow_other: close race between mknod and chown
If the user manages to replace the directory with
a symlink at just the right time, we could be tricked
into chown'ing the wrong file.

This change fixes the race by using fchownat, which
unfortunately is not available on darwin, hence a compat
wrapper is added.

Scenario, as described by @slackner at
https://github.com/rfjakob/gocryptfs/issues/177 :

1. Create a forward mount point with `plaintextnames` enabled
2. Mount as root user with `allow_other`
3. For testing purposes create a file `/tmp/file_owned_by_root`
   which is owned by the root user
4. As a regular user run inside of the GoCryptFS mount:

```
mkdir tempdir
mknod tempdir/file_owned_by_root p &
mv tempdir tempdir2
ln -s /tmp tempdir
```

When the steps are done fast enough and in the right order
(run in a loop!), the device file will be created in
`tempdir`, but the `lchown` will be executed by following
the symlink. As a result, the ownership of the file located
at `/tmp/file_owned_by_root` will be changed.
2017-11-27 21:04:45 +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
95870e841e fusefrontend: Skip gocryptfs.diriv handling when directory was deleted successfully
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
2017-11-25 16:20:00 +01:00
Sebastian Lackner
9f56b33e0c fusefrontend: Fix longname handling for renames with existing target
Fixes https://github.com/rfjakob/gocryptfs/issues/170

Steps to reproduce the problem:

* Create a regular forward mount point
* Create a file with a shortname and one with a long filename
* Try to run 'mv <shortname> <longname>'

This should actually work and replace the existing file, but instead it
fails with:

    mv: cannot move '<shortname>' to '<longname>': File exists

The problem is the creation of the .name file. If the target already exists
we can safely ignore the EEXIST error and just keep the existing .name file.
2017-11-25 16:19:09 +01:00
Sebastian Lackner
d257bb34c1 tests: Add test for access to encrypted version of '.' and '..'
To show that https://github.com/rfjakob/gocryptfs/issues/163 has been fixed.
2017-11-23 08:48:00 +01:00
Sebastian Lackner
f80f19f589 fusefrontend_reverse: Add a missing Close() call 2017-11-22 23:42:49 +01:00
Sebastian Lackner
c547673529 nametransform: Return error if decrypted name is '.' or '..' 2017-11-22 23:42:08 +01:00
Sebastian Lackner
f3c777d5ea main: Add '-devrandom' commandline option
Allows to use /dev/random for generating the master key instead of the
default Go implementation. When the kernel random generator has been
properly initialized both are considered equally secure, however:

* Versions of Go prior to 1.9 just fall back to /dev/urandom if the
  getrandom() syscall would be blocking (Go Bug #19274)

* Kernel versions prior to 3.17 do not support getrandom(), and there
  is no check if the random generator has been properly initialized
  before reading from /dev/urandom

This is especially useful for embedded hardware with low-entroy. Please
note that generation of the master key might block indefinitely if the
kernel cannot harvest enough entropy.
2017-11-21 23:37:06 +01:00
Jakob Unterwurzacher
1b0426bcb2 main: print clear error message if CIPHERDIR is missing
Getting just the help text in response to

	gocryptfs -info -config external.config

is confusing: https://github.com/rfjakob/gocryptfs/issues/157
2017-11-15 20:30:21 +01:00
Jakob Unterwurzacher
e36a0ebf18 main: add "-sharedstorage" flag
At the moment, it does two things:

1. Disable stat() caching so changes to the backing storage show up
   immediately.
2. Disable hard link tracking, as the inode numbers on the backing
   storage are not stable when files are deleted and re-created behind
   our back. This would otherwise produce strange "file does not exist"
   and other errors.

Mitigates https://github.com/rfjakob/gocryptfs/issues/156
2017-11-12 20:06:13 +01:00
Jakob Unterwurzacher
9ab6cdb9b9 test.bash: don't run "go tool vet" if vendor dir exists
...this fails in a thousand ways:

[...]
vendor/golang.org/x/crypto/sha3/keccakf_amd64.s:324: [amd64] keccakF1600: unknown variable state; offset 0 is a+0(FP)
vendor/golang.org/x/crypto/ssh/certs.go:172: declaration of "err" shadows declaration at vendor/golang.org/x/crypto/ssh/certs.go:166
vendor/golang.org/x/crypto/ssh/certs.go:187: declaration of "rest" shadows declaration at vendor/golang.org/x/crypto/ssh/certs.go:161
vendor/golang.org/x/crypto/ssh/certs.go:187: declaration of "ok" shadows declaration at vendor/golang.org/x/crypto/ssh/certs.go:161
vendor/golang.org/x/crypto/ssh/client_auth.go:226: declaration of "err" shadows declaration at vendor/golang.org/x/crypto/ssh/client_auth.go:193
vendor/golang.org/x/crypto/ssh/client_auth.go:394: declaration of "err" shadows declaration at vendor/golang.org/x/crypto/ssh/client_auth.go:380
vendor/golang.org/x/crypto/ssh/client_auth.go:405: declaration of "err" shadows declaration at vendor/golang.org/x/crypto/ssh/client_auth.go:380
vendor/golang.org/x/crypto/ssh/handshake.go:566: declaration of "err" shadows declaration at vendor/golang.org/x/crypto/ssh/handshake.go:547
vendor/golang.org/x/crypto/ssh/handshake.go:592: declaration of "err" shadows declaration at vendor/golang.org/x/crypto/ssh/handshake.go:547
vendor/golang.org/x/crypto/ssh/handshake.go:630: declaration of "err" shadows declaration at vendor/golang.org/x/crypto/ssh/handshake.go:620
[...]
2017-11-12 13:05:27 +01:00
Jakob Unterwurzacher
843138168f package-source.bash: replace plus sign in file name
Plus signs are apparently not supported on github,
and replaced by a dot.
2017-11-01 20:05:15 +01:00
Jakob Unterwurzacher
5428567fa0 package-source.bash: create VERSION file
...and delete if after packaging is done.
2017-11-01 19:41:47 +01:00
Jakob Unterwurzacher
6c2c2b9a8b README: Update changelog for v1.4.2 2017-11-01 19:29:11 +01:00
Jakob Unterwurzacher
2aaf9c6387 dep: update dependencies 2017-11-01 19:11:26 +01:00
Jakob Unterwurzacher
4c11e8a4e5 travis: update Go versions
...to latest point releases acc. to https://golang.org/dl/
2017-11-01 19:02:34 +01:00
Jakob Unterwurzacher
39839ade70 Add source packaging script 2017-11-01 18:58:10 +01:00
Jakob Unterwurzacher
9a3791fbc1 build.bash: support VERSION file and vendored go-fuse
Prepares for the release of all-in-one source tarballs
that include all non-stdlib dependencies.
2017-11-01 16:09:47 +01:00
Jakob Unterwurzacher
a1a98abfbb main: disallow recursively encrypting ourselves
From https://github.com/rfjakob/gocryptfs/issues/150:

  mkdir a
  mkdir a/b
  gocryptsfs -init -reverse a/
  gocryptfs -reverse a/ a/b

  Now directory a/b/ contains encrypted view of 'a' but it
  is possible to descend into encrypted version of b (e.g.
  a/b/43873uhj538765387/) which contains double encrypted
  'a' and so on.

Reported-by: https://github.com/tigmac
2017-10-31 19:48:01 +01:00
Jakob Unterwurzacher
34547a6c39 tests: don't read /proc, the number of entries changes too quickly
This could lead to test failures like this:

  --- FAIL: TestGetdents (0.02s)
  	getdents_test.go:57: len(getdentsEntries)=362, len(readdirEntries)=360
  FAIL
2017-10-22 18:13:08 +02:00