Merge release-20200907.0-37-g3ca73841d (automated)

1 files changed, 241 insertions, 107 deletions

diff --git a/pkg/sentry/fsimpl/fuse/connection.go b/pkg/sentry/fsimpl/fuse/connection.go
index a7402c149..eb1d1a2b7 100644
--- a/pkg/sentry/fsimpl/fuse/connection.go
+++ b/pkg/sentry/fsimpl/fuse/connection.go
@@ -15,17 +15,31 @@
 package fuse
 
 import (
+	"errors"
+	"fmt"
 	"sync"
+	"sync/atomic"
+	"syscall"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/log"
+	"gvisor.dev/gvisor/pkg/marshal"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
+	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/sentry/vfs"
 	"gvisor.dev/gvisor/pkg/syserror"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
 
+// maxActiveRequestsDefault is the default setting controlling the upper bound
+// on the number of active requests at any given time.
+const maxActiveRequestsDefault = 10000
+
+// Ordinary requests have even IDs, while interrupts IDs are odd.
+// Used to increment the unique ID for each FUSE request.
+var reqIDStep uint64 = 2
+
 const (
 	// fuseDefaultMaxBackground is the default value for MaxBackground.
 	fuseDefaultMaxBackground = 12
@@ -38,36 +52,43 @@ const (
 	fuseDefaultMaxPagesPerReq = 32
 )
 
+// Request represents a FUSE operation request that hasn't been sent to the
+// server yet.
+//
+// +stateify savable
+type Request struct {
+	requestEntry
+
+	id   linux.FUSEOpID
+	hdr  *linux.FUSEHeaderIn
+	data []byte
+}
+
+// Response represents an actual response from the server, including the
+// response payload.
+//
+// +stateify savable
+type Response struct {
+	opcode linux.FUSEOpcode
+	hdr    linux.FUSEHeaderOut
+	data   []byte
+}
+
 // connection is the struct by which the sentry communicates with the FUSE server daemon.
-// Lock order:
-// - conn.fd.mu
-// - conn.mu
-// - conn.asyncMu
 type connection struct {
 	fd *DeviceFD
 
-	// mu protects access to struct memebers.
-	mu sync.Mutex
-
-	// attributeVersion is the version of connection's attributes.
-	attributeVersion uint64
-
-	// We target FUSE 7.23.
 	// The following FUSE_INIT flags are currently unsupported by this implementation:
+	// - FUSE_ATOMIC_O_TRUNC: requires open(..., O_TRUNC)
 	// - FUSE_EXPORT_SUPPORT
+	// - FUSE_HANDLE_KILLPRIV
 	// - FUSE_POSIX_LOCKS: requires POSIX locks
 	// - FUSE_FLOCK_LOCKS: requires POSIX locks
 	// - FUSE_AUTO_INVAL_DATA: requires page caching eviction
+	// - FUSE_EXPLICIT_INVAL_DATA: requires page caching eviction
 	// - FUSE_DO_READDIRPLUS/FUSE_READDIRPLUS_AUTO: requires FUSE_READDIRPLUS implementation
 	// - FUSE_ASYNC_DIO
-	// - FUSE_PARALLEL_DIROPS (7.25)
-	// - FUSE_HANDLE_KILLPRIV (7.26)
-	// - FUSE_POSIX_ACL: affects defaultPermissions, posixACL, xattr handler (7.26)
-	// - FUSE_ABORT_ERROR (7.27)
-	// - FUSE_CACHE_SYMLINKS (7.28)
-	// - FUSE_NO_OPENDIR_SUPPORT (7.29)
-	// - FUSE_EXPLICIT_INVAL_DATA: requires page caching eviction (7.30)
-	// - FUSE_MAP_ALIGNMENT (7.31)
+	// - FUSE_POSIX_ACL: affects defaultPermissions, posixACL, xattr handler
 
 	// initialized after receiving FUSE_INIT reply.
 	// Until it's set, suspend sending FUSE requests.
@@ -77,6 +98,10 @@ type connection struct {
 	// initializedChan is used to block requests before initialization.
 	initializedChan chan struct{}
 
+	// blocked when there are too many outstading backgrounds requests (NumBackground == MaxBackground).
+	// TODO(gvisor.dev/issue/3185): update the numBackground accordingly; use a channel to block.
+	blocked bool
+
 	// connected (connection established) when a new FUSE file system is created.
 	// Set to false when:
 	//   umount,
@@ -84,55 +109,48 @@ type connection struct {
 	//   device release.
 	connected bool
 
+	// aborted via sysfs.
+	// TODO(gvisor.dev/issue/3185): abort all queued requests.
+	aborted bool
+
 	// connInitError if FUSE_INIT encountered error (major version mismatch).
 	// Only set in INIT.
 	connInitError bool
 
 	// connInitSuccess if FUSE_INIT is successful.
 	// Only set in INIT.
-	// Used for destory (not yet implemented).
+	// Used for destory.
 	connInitSuccess bool
 
-	// aborted via sysfs, and will send ECONNABORTED to read after disconnection (instead of ENODEV).
-	// Set only if abortErr is true and via fuse control fs (not yet implemented).
-	// TODO(gvisor.dev/issue/3525): set this to true when user aborts.
-	aborted bool
+	// TODO(gvisor.dev/issue/3185): All the queue logic are working in progress.
 
-	// numWating is the number of requests waiting to be
-	// sent to FUSE device or being processed by FUSE daemon.
-	numWaiting uint32
+	// NumberBackground is the number of requests in the background.
+	numBackground uint16
 
-	// Terminology note:
-	//
-	// - `asyncNumMax` is the `MaxBackground` in the FUSE_INIT_IN struct.
-	//
-	// - `asyncCongestionThreshold` is the `CongestionThreshold` in the FUSE_INIT_IN struct.
-	//
-	// We call the "background" requests in unix term as async requests.
-	// The "async requests" in unix term is our async requests that expect a reply,
-	// i.e. `!requestOptions.noReply`
+	// congestionThreshold for NumBackground.
+	// Negotiated in FUSE_INIT.
+	congestionThreshold uint16
+
+	// maxBackground is the maximum number of NumBackground.
+	// Block connection when it is reached.
+	// Negotiated in FUSE_INIT.
+	maxBackground uint16
 
-	// asyncMu protects the async request fields.
-	asyncMu sync.Mutex
+	// numActiveBackground is the number of requests in background and has being marked as active.
+	numActiveBackground uint16
 
-	// asyncNum is the number of async requests.
-	// Protected by asyncMu.
-	asyncNum uint16
+	// numWating is the number of requests waiting for completion.
+	numWaiting uint32
 
-	// asyncCongestionThreshold the number of async requests.
-	// Negotiated in FUSE_INIT as "CongestionThreshold".
-	// TODO(gvisor.dev/issue/3529): add congestion control.
-	// Protected by asyncMu.
-	asyncCongestionThreshold uint16
+	// TODO(gvisor.dev/issue/3185): BgQueue
+	// some queue for background queued requests.
 
-	// asyncNumMax is the maximum number of asyncNum.
-	// Connection blocks the async requests when it is reached.
-	// Negotiated in FUSE_INIT as "MaxBackground".
-	// Protected by asyncMu.
-	asyncNumMax uint16
+	// bgLock protects:
+	// MaxBackground, CongestionThreshold, NumBackground,
+	// NumActiveBackground, BgQueue, Blocked.
+	bgLock sync.Mutex
 
 	// maxRead is the maximum size of a read buffer in in bytes.
-	// Initialized from a fuse fs parameter.
 	maxRead uint32
 
 	// maxWrite is the maximum size of a write buffer in bytes.
@@ -147,20 +165,23 @@ type connection struct {
 	// Negotiated and only set in INIT.
 	minor uint32
 
-	// atomicOTrunc is true when FUSE does not send a separate SETATTR request
-	// before open with O_TRUNC flag.
-	// Negotiated and only set in INIT.
-	atomicOTrunc bool
-
 	// asyncRead if read pages asynchronously.
 	// Negotiated and only set in INIT.
 	asyncRead bool
 
+	// abortErr is true if kernel need to return an unique read error after abort.
+	// Negotiated and only set in INIT.
+	abortErr bool
+
 	// writebackCache is true for write-back cache policy,
 	// false for write-through policy.
 	// Negotiated and only set in INIT.
 	writebackCache bool
 
+	// cacheSymlinks if filesystem needs to cache READLINK responses in page cache.
+	// Negotiated and only set in INIT.
+	cacheSymlinks bool
+
 	// bigWrites if doing multi-page cached writes.
 	// Negotiated and only set in INIT.
 	bigWrites bool
@@ -168,70 +189,116 @@ type connection struct {
 	// dontMask if filestestem does not apply umask to creation modes.
 	// Negotiated in INIT.
 	dontMask bool
-
-	// noOpen if FUSE server doesn't support open operation.
-	// This flag only influence performance, not correctness of the program.
-	noOpen bool
 }
 
 // newFUSEConnection creates a FUSE connection to fd.
-func newFUSEConnection(_ context.Context, fd *vfs.FileDescription, opts *filesystemOptions) (*connection, error) {
+func newFUSEConnection(_ context.Context, fd *vfs.FileDescription, maxInFlightRequests uint64) (*connection, error) {
 	// Mark the device as ready so it can be used. /dev/fuse can only be used if the FD was used to
 	// mount a FUSE filesystem.
 	fuseFD := fd.Impl().(*DeviceFD)
+	fuseFD.mounted = true
 
 	// Create the writeBuf for the header to be stored in.
 	hdrLen := uint32((*linux.FUSEHeaderOut)(nil).SizeBytes())
 	fuseFD.writeBuf = make([]byte, hdrLen)
 	fuseFD.completions = make(map[linux.FUSEOpID]*futureResponse)
-	fuseFD.fullQueueCh = make(chan struct{}, opts.maxActiveRequests)
+	fuseFD.fullQueueCh = make(chan struct{}, maxInFlightRequests)
 	fuseFD.writeCursor = 0
 
 	return &connection{
-		fd:                       fuseFD,
-		asyncNumMax:              fuseDefaultMaxBackground,
-		asyncCongestionThreshold: fuseDefaultCongestionThreshold,
-		maxRead:                  opts.maxRead,
-		maxPages:                 fuseDefaultMaxPagesPerReq,
-		initializedChan:          make(chan struct{}),
-		connected:                true,
+		fd:                  fuseFD,
+		maxBackground:       fuseDefaultMaxBackground,
+		congestionThreshold: fuseDefaultCongestionThreshold,
+		maxPages:            fuseDefaultMaxPagesPerReq,
+		initializedChan:     make(chan struct{}),
+		connected:           true,
 	}, nil
 }
 
-// CallAsync makes an async (aka background) request.
-// It's a simple wrapper around Call().
-func (conn *connection) CallAsync(t *kernel.Task, r *Request) error {
-	r.async = true
-	_, err := conn.Call(t, r)
-	return err
+// SetInitialized atomically sets the connection as initialized.
+func (conn *connection) SetInitialized() {
+	// Unblock the requests sent before INIT.
+	close(conn.initializedChan)
+
+	// Close the channel first to avoid the non-atomic situation
+	// where conn.initialized is true but there are
+	// tasks being blocked on the channel.
+	// And it prevents the newer tasks from gaining
+	// unnecessary higher chance to be issued before the blocked one.
+
+	atomic.StoreInt32(&(conn.initialized), int32(1))
 }
 
-// Call makes a request to the server.
-// Block before the connection is initialized.
-// When the Request is FUSE_INIT, it will not be blocked before initialization.
-// Task should never be nil.
-//
-// For a sync request, it blocks the invoking task until
-// a server responds with a response.
-//
-// For an async request (that do not expect a response immediately),
-// it returns directly unless being blocked either before initialization
-// or when there are too many async requests ongoing.
-//
-// Example for async request:
-// init, readahead, write, async read/write, fuse_notify_reply,
-// non-sync release, interrupt, forget.
-//
-// The forget request does not have a reply,
-// as documented in include/uapi/linux/fuse.h:FUSE_FORGET.
+// IsInitialized atomically check if the connection is initialized.
+// pairs with SetInitialized().
+func (conn *connection) Initialized() bool {
+	return atomic.LoadInt32(&(conn.initialized)) != 0
+}
+
+// NewRequest creates a new request that can be sent to the FUSE server.
+func (conn *connection) NewRequest(creds *auth.Credentials, pid uint32, ino uint64, opcode linux.FUSEOpcode, payload marshal.Marshallable) (*Request, error) {
+	conn.fd.mu.Lock()
+	defer conn.fd.mu.Unlock()
+	conn.fd.nextOpID += linux.FUSEOpID(reqIDStep)
+
+	hdrLen := (*linux.FUSEHeaderIn)(nil).SizeBytes()
+	hdr := linux.FUSEHeaderIn{
+		Len:    uint32(hdrLen + payload.SizeBytes()),
+		Opcode: opcode,
+		Unique: conn.fd.nextOpID,
+		NodeID: ino,
+		UID:    uint32(creds.EffectiveKUID),
+		GID:    uint32(creds.EffectiveKGID),
+		PID:    pid,
+	}
+
+	buf := make([]byte, hdr.Len)
+	hdr.MarshalUnsafe(buf[:hdrLen])
+	payload.MarshalUnsafe(buf[hdrLen:])
+
+	return &Request{
+		id:   hdr.Unique,
+		hdr:  &hdr,
+		data: buf,
+	}, nil
+}
+
+// Call makes a request to the server and blocks the invoking task until a
+// server responds with a response. Task should never be nil.
+// Requests will not be sent before the connection is initialized.
+// For async tasks, use CallAsync().
 func (conn *connection) Call(t *kernel.Task, r *Request) (*Response, error) {
 	// Block requests sent before connection is initalized.
-	if !conn.Initialized() && r.hdr.Opcode != linux.FUSE_INIT {
+	if !conn.Initialized() {
 		if err := t.Block(conn.initializedChan); err != nil {
 			return nil, err
 		}
 	}
 
+	return conn.call(t, r)
+}
+
+// CallAsync makes an async (aka background) request.
+// Those requests either do not expect a response (e.g. release) or
+// the response should be handled by others (e.g. init).
+// Return immediately unless the connection is blocked (before initialization).
+// Async call example: init, release, forget, aio, interrupt.
+// When the Request is FUSE_INIT, it will not be blocked before initialization.
+func (conn *connection) CallAsync(t *kernel.Task, r *Request) error {
+	// Block requests sent before connection is initalized.
+	if !conn.Initialized() && r.hdr.Opcode != linux.FUSE_INIT {
+		if err := t.Block(conn.initializedChan); err != nil {
+			return err
+		}
+	}
+
+	// This should be the only place that invokes call() with a nil task.
+	_, err := conn.call(nil, r)
+	return err
+}
+
+// call makes a call without blocking checks.
+func (conn *connection) call(t *kernel.Task, r *Request) (*Response, error) {
 	if !conn.connected {
 		return nil, syserror.ENOTCONN
 	}
@@ -248,6 +315,31 @@ func (conn *connection) Call(t *kernel.Task, r *Request) (*Response, error) {
 	return fut.resolve(t)
 }
 
+// Error returns the error of the FUSE call.
+func (r *Response) Error() error {
+	errno := r.hdr.Error
+	if errno >= 0 {
+		return nil
+	}
+
+	sysErrNo := syscall.Errno(-errno)
+	return error(sysErrNo)
+}
+
+// UnmarshalPayload unmarshals the response data into m.
+func (r *Response) UnmarshalPayload(m marshal.Marshallable) error {
+	hdrLen := r.hdr.SizeBytes()
+	haveDataLen := r.hdr.Len - uint32(hdrLen)
+	wantDataLen := uint32(m.SizeBytes())
+
+	if haveDataLen < wantDataLen {
+		return fmt.Errorf("payload too small. Minimum data lenth required: %d,  but got data length %d", wantDataLen, haveDataLen)
+	}
+
+	m.UnmarshalUnsafe(r.data[hdrLen:])
+	return nil
+}
+
 // callFuture makes a request to the server and returns a future response.
 // Call resolve() when the response needs to be fulfilled.
 func (conn *connection) callFuture(t *kernel.Task, r *Request) (*futureResponse, error) {
@@ -266,6 +358,11 @@ func (conn *connection) callFuture(t *kernel.Task, r *Request) (*futureResponse,
 	// if there are always too many ongoing requests all the time. The
 	// supported maxActiveRequests setting should be really high to avoid this.
 	for conn.fd.numActiveRequests == conn.fd.fs.opts.maxActiveRequests {
+		if t == nil {
+			// Since there is no task that is waiting. We must error out.
+			return nil, errors.New("FUSE request queue full")
+		}
+
 		log.Infof("Blocking request %v from being queued. Too many active requests: %v",
 			r.id, conn.fd.numActiveRequests)
 		conn.fd.mu.Unlock()
@@ -281,19 +378,9 @@ func (conn *connection) callFuture(t *kernel.Task, r *Request) (*futureResponse,
 
 // callFutureLocked makes a request to the server and returns a future response.
 func (conn *connection) callFutureLocked(t *kernel.Task, r *Request) (*futureResponse, error) {
-	// Check connected again holding conn.mu.
-	conn.mu.Lock()
-	if !conn.connected {
-		conn.mu.Unlock()
-		// we checked connected before,
-		// this must be due to aborted connection.
-		return nil, syserror.ECONNABORTED
-	}
-	conn.mu.Unlock()
-
 	conn.fd.queue.PushBack(r)
-	conn.fd.numActiveRequests++
-	fut := newFutureResponse(r)
+	conn.fd.numActiveRequests += 1
+	fut := newFutureResponse(r.hdr.Opcode)
 	conn.fd.completions[r.id] = fut
 
 	// Signal the readers that there is something to read.
@@ -301,3 +388,50 @@ func (conn *connection) callFutureLocked(t *kernel.Task, r *Request) (*futureRes
 
 	return fut, nil
 }
+
+// futureResponse represents an in-flight request, that may or may not have
+// completed yet. Convert it to a resolved Response by calling Resolve, but note
+// that this may block.
+//
+// +stateify savable
+type futureResponse struct {
+	opcode linux.FUSEOpcode
+	ch     chan struct{}
+	hdr    *linux.FUSEHeaderOut
+	data   []byte
+}
+
+// newFutureResponse creates a future response to a FUSE request.
+func newFutureResponse(opcode linux.FUSEOpcode) *futureResponse {
+	return &futureResponse{
+		opcode: opcode,
+		ch:     make(chan struct{}),
+	}
+}
+
+// resolve blocks the task until the server responds to its corresponding request,
+// then returns a resolved response.
+func (f *futureResponse) resolve(t *kernel.Task) (*Response, error) {
+	// If there is no Task associated with this request  - then we don't try to resolve
+	// the response.  Instead, the task writing the response (proxy to the server) will
+	// process the response on our behalf.
+	if t == nil {
+		log.Infof("fuse.Response.resolve: Not waiting on a response from server.")
+		return nil, nil
+	}
+
+	if err := t.Block(f.ch); err != nil {
+		return nil, err
+	}
+
+	return f.getResponse(), nil
+}
+
+// getResponse creates a Response from the data the futureResponse has.
+func (f *futureResponse) getResponse() *Response {
+	return &Response{
+		opcode: f.opcode,
+		hdr:    *f.hdr,
+		data:   f.data,
+	}
+}