Resolves symlink escape when unarchiving by removing existing paths within the same allocation directory which can occur by writing a header that points to a symlink that lives outside of the sandbox environment. This exploit requires first compromising the Nomad client agent at the source allocation.
Ref: https://hashicorp.atlassian.net/browse/NET-10607
Ref: https://github.com/hashicorp/nomad-enterprise/pull/1725
During allocation directory migration, the client was not checking that any
symlinks in the archive aren't pointing to somewhere outside the allocation
directory. While task driver sandboxing will protect against processes inside
the task from reading/writing thru the symlink, this doesn't protect against the
client itself from performing unintended operations outside the sandbox.
This changeset includes two changes:
* Update the archive unpacking to check the source of symlinks and require that
they fall within the sandbox.
* Fix a bug in the symlink check where it was using `filepath.Rel` which doesn't
work for paths in the sibling directories of the sandbox directory. This bug
doesn't appear to be exploitable but caused errors in testing.
Fixes: https://github.com/hashicorp/nomad/issues/19887
* Update ioutil deprecated library references to os and io respectively
* Deal with the errors produced.
Add error handling to filEntry info
Add error handling to info
* test: use `T.TempDir` to create temporary test directory
This commit replaces `ioutil.TempDir` with `t.TempDir` in tests. The
directory created by `t.TempDir` is automatically removed when the test
and all its subtests complete.
Prior to this commit, temporary directory created using `ioutil.TempDir`
needs to be removed manually by calling `os.RemoveAll`, which is omitted
in some tests. The error handling boilerplate e.g.
defer func() {
if err := os.RemoveAll(dir); err != nil {
t.Fatal(err)
}
}
is also tedious, but `t.TempDir` handles this for us nicely.
Reference: https://pkg.go.dev/testing#T.TempDir
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>
* test: fix TestLogmon_Start_restart on Windows
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>
* test: fix failing TestConsul_Integration
t.TempDir fails to perform the cleanup properly because the folder is
still in use
testing.go:967: TempDir RemoveAll cleanup: unlinkat /tmp/TestConsul_Integration2837567823/002/191a6f1a-5371-cf7c-da38-220fe85d10e5/web/secrets: device or resource busy
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>
