Writing to the mount with os.WriteFile made the Go runtime register
the file with its poller so the kernel then polled the file from
epoll_ctl and epoll_wait, sending POLL requests to the FUSE server
running in this same process. A thread waiting inside epoll cannot be
preempted by the runtime, so a garbage collection starting while such
a POLL was outstanding stopped the world for good - the test binary
could not be killed even with SIGKILL and the mount was left behind,
wedging anything that touched it.
Now we write through the mount with a descriptor straight from
open(2), which os.NewFile keeps out of the poller, check that it
really is out of the poller with SetDeadline, and check at the end of
the test that the mountpoint is unmounted.
In this commit we fixed the same problem for mount by running in a
subprocess however changing one write file routine here was much
easier than re-arranging the tests.
4a382c09ec mount: run tests in a subprocess to fix deadlock - #3259
Note that go-fuse (and hence mount2) works around this problem it by
forcing an early POLL it can answer with ENOSYS.
See: https://github.com/golang/go/issues/21014
An empty or "." volume name joined onto the base directory resolves to the
base directory itself. newVolume does not call validate, so such a name
would mount a remote over the base directory and shadow every other
volume's mountpoint.
Require the resolved mountpoint to be a strict descendant of the base
directory so these degenerate names are refused.
When the plugin restarts it reads its persisted state file and used the
stored mountpoint verbatim. A state file written by an older rclone that
allowed escaping volume names, or one that was tampered with, could point
the mountpoint outside the base directory, so upgrading did not remediate
an already-escaped volume.
Re-derive the mountpoint from the base directory and the volume name on
restore, confined to the base directory, rather than trusting the stored
path.
A Docker VolumeDriver.Create request carries a raw volume name that was
joined onto the base directory with filepath.Join and used verbatim as the
mountpoint. filepath.Join collapses ".." components, so a crafted name such
as "../../../etc/foo" resolved to a host path outside the base directory,
where the plugin then created a directory and mounted the remote.
Confine the mountpoint to the base directory and refuse any name that
resolves outside it.
Docker may re-send Create requests for volumes that already exist,
especially after a plugin restart. Previously this returned
ErrVolumeExists which Docker surfaced as "volume name must be unique".
Now if a volume with the same name already exists, Create returns
success (no-op), matching the Docker volume plugin protocol's
expectation of idempotent operations.
Previously, restoreState in NewDriver would restore volumes AND perform
FUSE mounts synchronously before the Docker plugin socket was created.
This caused two problems:
1. The monChan was created after restoreState, but mount() sends on
monChan, causing a deadlock (send on nil channel blocks forever).
2. Even with the channel fix, slow or hanging mounts during state
restore would block the server socket from being created, causing
Docker to time out after ~13 seconds with "no such file or
directory" for the plugin socket.
Fix by:
- Moving monChan creation and monitor goroutine start before
restoreState
- Splitting state restore into two phases: restoreState (metadata +
filesystem setup only) and RestoreMounts (actual FUSE mounts)
- Calling RestoreMounts asynchronously after the server starts
listening
- Performing mount restoration concurrently across volumes
Fixes#9231
This commit modernizes Go usage. This was done with:
go run golang.org/x/tools/gopls/internal/analysis/modernize/cmd/modernize@latest -fix -test ./...
Then files needed to be `go fmt`ed and a few comments needed to be
restored.
The modernizations include replacing
- if/else conditional assignment by a call to the built-in min or max functions added in go1.21
- sort.Slice(x, func(i, j int) bool) { return s[i] < s[j] } by a call to slices.Sort(s), added in go1.21
- interface{} by the 'any' type added in go1.18
- append([]T(nil), s...) by slices.Clone(s) or slices.Concat(s), added in go1.21
- loop around an m[k]=v map update by a call to one of the Collect, Copy, Clone, or Insert functions from the maps package, added in go1.21
- []byte(fmt.Sprintf...) by fmt.Appendf(nil, ...), added in go1.19
- append(s[:i], s[i+1]...) by slices.Delete(s, i, i+1), added in go1.21
- a 3-clause for i := 0; i < n; i++ {} loop by for i := range n {}, added in go1.22
This replaces built-in os.MkdirAll with a patched version that stops the recursion
when reaching the volume part of the path. The original version would continue recursion,
and for extended length paths end up with \\? as the top-level directory, and the error
message would then be something like:
mkdir \\?: The filename, directory name, or volume label syntax is incorrect.
Nick Craig-Wood
albertony
Ivan Andreev
Antoine GIRARDandIvan Andreev