diff options
Diffstat (limited to 'pkg/sentry/fsimpl/fuse')
| -rw-r--r-- | pkg/sentry/fsimpl/fuse/BUILD | 76 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/fuse/dev_test.go | 428 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/fuse/fuse_state_autogen.go | 184 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/fuse/inode_refs.go | 118 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/fuse/request_list.go | 193 |
5 files changed, 495 insertions, 504 deletions
diff --git a/pkg/sentry/fsimpl/fuse/BUILD b/pkg/sentry/fsimpl/fuse/BUILD deleted file mode 100644 index 53a4f3012..000000000 --- a/pkg/sentry/fsimpl/fuse/BUILD +++ /dev/null @@ -1,76 +0,0 @@ -load("//tools:defs.bzl", "go_library", "go_test") -load("//tools/go_generics:defs.bzl", "go_template_instance") - -licenses(["notice"]) - -go_template_instance( - name = "request_list", - out = "request_list.go", - package = "fuse", - prefix = "request", - template = "//pkg/ilist:generic_list", - types = { - "Element": "*Request", - "Linker": "*Request", - }, -) - -go_template_instance( - name = "inode_refs", - out = "inode_refs.go", - package = "fuse", - prefix = "inode", - template = "//pkg/refs_vfs2:refs_template", - types = { - "T": "inode", - }, -) - -go_library( - name = "fuse", - srcs = [ - "connection.go", - "dev.go", - "fusefs.go", - "init.go", - "inode_refs.go", - "register.go", - "request_list.go", - ], - visibility = ["//pkg/sentry:internal"], - deps = [ - "//pkg/abi/linux", - "//pkg/context", - "//pkg/log", - "//pkg/refs", - "//pkg/sentry/fsimpl/devtmpfs", - "//pkg/sentry/fsimpl/kernfs", - "//pkg/sentry/kernel", - "//pkg/sentry/kernel/auth", - "//pkg/sentry/vfs", - "//pkg/sync", - "//pkg/syserror", - "//pkg/usermem", - "//pkg/waiter", - "//tools/go_marshal/marshal", - "@org_golang_x_sys//unix:go_default_library", - ], -) - -go_test( - name = "fuse_test", - size = "small", - srcs = ["dev_test.go"], - library = ":fuse", - deps = [ - "//pkg/abi/linux", - "//pkg/sentry/fsimpl/testutil", - "//pkg/sentry/kernel", - "//pkg/sentry/kernel/auth", - "//pkg/sentry/vfs", - "//pkg/syserror", - "//pkg/usermem", - "//pkg/waiter", - "//tools/go_marshal/marshal", - ], -) diff --git a/pkg/sentry/fsimpl/fuse/dev_test.go b/pkg/sentry/fsimpl/fuse/dev_test.go deleted file mode 100644 index 1ffe7ccd2..000000000 --- a/pkg/sentry/fsimpl/fuse/dev_test.go +++ /dev/null @@ -1,428 +0,0 @@ -// Copyright 2020 The gVisor Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -package fuse - -import ( - "fmt" - "io" - "math/rand" - "testing" - - "gvisor.dev/gvisor/pkg/abi/linux" - "gvisor.dev/gvisor/pkg/sentry/fsimpl/testutil" - "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/usermem" - "gvisor.dev/gvisor/pkg/waiter" - "gvisor.dev/gvisor/tools/go_marshal/marshal" -) - -// echoTestOpcode is the Opcode used during testing. The server used in tests -// will simply echo the payload back with the appropriate headers. -const echoTestOpcode linux.FUSEOpcode = 1000 - -type testPayload struct { - data uint32 -} - -// TestFUSECommunication tests that the communication layer between the Sentry and the -// FUSE server daemon works as expected. -func TestFUSECommunication(t *testing.T) { - s := setup(t) - defer s.Destroy() - - k := kernel.KernelFromContext(s.Ctx) - creds := auth.CredentialsFromContext(s.Ctx) - - // Create test cases with different number of concurrent clients and servers. - testCases := []struct { - Name string - NumClients int - NumServers int - MaxActiveRequests uint64 - }{ - { - Name: "SingleClientSingleServer", - NumClients: 1, - NumServers: 1, - MaxActiveRequests: maxActiveRequestsDefault, - }, - { - Name: "SingleClientMultipleServers", - NumClients: 1, - NumServers: 10, - MaxActiveRequests: maxActiveRequestsDefault, - }, - { - Name: "MultipleClientsSingleServer", - NumClients: 10, - NumServers: 1, - MaxActiveRequests: maxActiveRequestsDefault, - }, - { - Name: "MultipleClientsMultipleServers", - NumClients: 10, - NumServers: 10, - MaxActiveRequests: maxActiveRequestsDefault, - }, - { - Name: "RequestCapacityFull", - NumClients: 10, - NumServers: 1, - MaxActiveRequests: 1, - }, - { - Name: "RequestCapacityContinuouslyFull", - NumClients: 100, - NumServers: 2, - MaxActiveRequests: 2, - }, - } - - for _, testCase := range testCases { - t.Run(testCase.Name, func(t *testing.T) { - conn, fd, err := newTestConnection(s, k, testCase.MaxActiveRequests) - if err != nil { - t.Fatalf("newTestConnection: %v", err) - } - - clientsDone := make([]chan struct{}, testCase.NumClients) - serversDone := make([]chan struct{}, testCase.NumServers) - serversKill := make([]chan struct{}, testCase.NumServers) - - // FUSE clients. - for i := 0; i < testCase.NumClients; i++ { - clientsDone[i] = make(chan struct{}) - go func(i int) { - fuseClientRun(t, s, k, conn, creds, uint32(i), uint64(i), clientsDone[i]) - }(i) - } - - // FUSE servers. - for j := 0; j < testCase.NumServers; j++ { - serversDone[j] = make(chan struct{}) - serversKill[j] = make(chan struct{}, 1) // The kill command shouldn't block. - go func(j int) { - fuseServerRun(t, s, k, fd, serversDone[j], serversKill[j]) - }(j) - } - - // Tear down. - // - // Make sure all the clients are done. - for i := 0; i < testCase.NumClients; i++ { - <-clientsDone[i] - } - - // Kill any server that is potentially waiting. - for j := 0; j < testCase.NumServers; j++ { - serversKill[j] <- struct{}{} - } - - // Make sure all the servers are done. - for j := 0; j < testCase.NumServers; j++ { - <-serversDone[j] - } - }) - } -} - -// CallTest makes a request to the server and blocks the invoking -// goroutine until a server responds with a response. Doesn't block -// a kernel.Task. Analogous to Connection.Call but used for testing. -func CallTest(conn *connection, t *kernel.Task, r *Request, i uint32) (*Response, error) { - conn.fd.mu.Lock() - - // Wait until we're certain that a new request can be processed. - for conn.fd.numActiveRequests == conn.fd.fs.opts.maxActiveRequests { - conn.fd.mu.Unlock() - select { - case <-conn.fd.fullQueueCh: - } - conn.fd.mu.Lock() - } - - fut, err := conn.callFutureLocked(t, r) // No task given. - conn.fd.mu.Unlock() - - if err != nil { - return nil, err - } - - // Resolve the response. - // - // Block without a task. - select { - case <-fut.ch: - } - - // A response is ready. Resolve and return it. - return fut.getResponse(), nil -} - -// ReadTest is analogous to vfs.FileDescription.Read and reads from the FUSE -// device. However, it does so by - not blocking the task that is calling - and -// instead just waits on a channel. The behaviour is essentially the same as -// DeviceFD.Read except it guarantees that the task is not blocked. -func ReadTest(serverTask *kernel.Task, fd *vfs.FileDescription, inIOseq usermem.IOSequence, killServer chan struct{}) (int64, bool, error) { - var err error - var n, total int64 - - dev := fd.Impl().(*DeviceFD) - - // Register for notifications. - w, ch := waiter.NewChannelEntry(nil) - dev.EventRegister(&w, waiter.EventIn) - for { - // Issue the request and break out if it completes with anything other than - // "would block". - n, err = dev.Read(serverTask, inIOseq, vfs.ReadOptions{}) - total += n - if err != syserror.ErrWouldBlock { - break - } - - // Wait for a notification that we should retry. - // Emulate the blocking for when no requests are available - select { - case <-ch: - case <-killServer: - // Server killed by the main program. - return 0, true, nil - } - } - - dev.EventUnregister(&w) - return total, false, err -} - -// fuseClientRun emulates all the actions of a normal FUSE request. It creates -// a header, a payload, calls the server, waits for the response, and processes -// the response. -func fuseClientRun(t *testing.T, s *testutil.System, k *kernel.Kernel, conn *connection, creds *auth.Credentials, pid uint32, inode uint64, clientDone chan struct{}) { - defer func() { clientDone <- struct{}{} }() - - tc := k.NewThreadGroup(nil, k.RootPIDNamespace(), kernel.NewSignalHandlers(), linux.SIGCHLD, k.GlobalInit().Limits()) - clientTask, err := testutil.CreateTask(s.Ctx, fmt.Sprintf("fuse-client-%v", pid), tc, s.MntNs, s.Root, s.Root) - if err != nil { - t.Fatal(err) - } - testObj := &testPayload{ - data: rand.Uint32(), - } - - req, err := conn.NewRequest(creds, pid, inode, echoTestOpcode, testObj) - if err != nil { - t.Fatalf("NewRequest creation failed: %v", err) - } - - // Queue up a request. - // Analogous to Call except it doesn't block on the task. - resp, err := CallTest(conn, clientTask, req, pid) - if err != nil { - t.Fatalf("CallTaskNonBlock failed: %v", err) - } - - if err = resp.Error(); err != nil { - t.Fatalf("Server responded with an error: %v", err) - } - - var respTestPayload testPayload - if err := resp.UnmarshalPayload(&respTestPayload); err != nil { - t.Fatalf("Unmarshalling payload error: %v", err) - } - - if resp.hdr.Unique != req.hdr.Unique { - t.Fatalf("got response for another request. Expected response for req %v but got response for req %v", - req.hdr.Unique, resp.hdr.Unique) - } - - if respTestPayload.data != testObj.data { - t.Fatalf("read incorrect data. Data expected: %v, but got %v", testObj.data, respTestPayload.data) - } - -} - -// fuseServerRun creates a task and emulates all the actions of a simple FUSE server -// that simply reads a request and echos the same struct back as a response using the -// appropriate headers. -func fuseServerRun(t *testing.T, s *testutil.System, k *kernel.Kernel, fd *vfs.FileDescription, serverDone, killServer chan struct{}) { - defer func() { serverDone <- struct{}{} }() - - // Create the tasks that the server will be using. - tc := k.NewThreadGroup(nil, k.RootPIDNamespace(), kernel.NewSignalHandlers(), linux.SIGCHLD, k.GlobalInit().Limits()) - var readPayload testPayload - - serverTask, err := testutil.CreateTask(s.Ctx, "fuse-server", tc, s.MntNs, s.Root, s.Root) - if err != nil { - t.Fatal(err) - } - - // Read the request. - for { - inHdrLen := uint32((*linux.FUSEHeaderIn)(nil).SizeBytes()) - payloadLen := uint32(readPayload.SizeBytes()) - - // The raed buffer must meet some certain size criteria. - buffSize := inHdrLen + payloadLen - if buffSize < linux.FUSE_MIN_READ_BUFFER { - buffSize = linux.FUSE_MIN_READ_BUFFER - } - inBuf := make([]byte, buffSize) - inIOseq := usermem.BytesIOSequence(inBuf) - - n, serverKilled, err := ReadTest(serverTask, fd, inIOseq, killServer) - if err != nil { - t.Fatalf("Read failed :%v", err) - } - - // Server should shut down. No new requests are going to be made. - if serverKilled { - break - } - - if n <= 0 { - t.Fatalf("Read read no bytes") - } - - var readFUSEHeaderIn linux.FUSEHeaderIn - readFUSEHeaderIn.UnmarshalUnsafe(inBuf[:inHdrLen]) - readPayload.UnmarshalUnsafe(inBuf[inHdrLen : inHdrLen+payloadLen]) - - if readFUSEHeaderIn.Opcode != echoTestOpcode { - t.Fatalf("read incorrect data. Header: %v, Payload: %v", readFUSEHeaderIn, readPayload) - } - - // Write the response. - outHdrLen := uint32((*linux.FUSEHeaderOut)(nil).SizeBytes()) - outBuf := make([]byte, outHdrLen+payloadLen) - outHeader := linux.FUSEHeaderOut{ - Len: outHdrLen + payloadLen, - Error: 0, - Unique: readFUSEHeaderIn.Unique, - } - - // Echo the payload back. - outHeader.MarshalUnsafe(outBuf[:outHdrLen]) - readPayload.MarshalUnsafe(outBuf[outHdrLen:]) - outIOseq := usermem.BytesIOSequence(outBuf) - - n, err = fd.Write(s.Ctx, outIOseq, vfs.WriteOptions{}) - if err != nil { - t.Fatalf("Write failed :%v", err) - } - } -} - -func setup(t *testing.T) *testutil.System { - k, err := testutil.Boot() - if err != nil { - t.Fatalf("Error creating kernel: %v", err) - } - - ctx := k.SupervisorContext() - creds := auth.CredentialsFromContext(ctx) - - k.VFS().MustRegisterFilesystemType(Name, &FilesystemType{}, &vfs.RegisterFilesystemTypeOptions{ - AllowUserList: true, - AllowUserMount: true, - }) - - mntns, err := k.VFS().NewMountNamespace(ctx, creds, "", "tmpfs", &vfs.GetFilesystemOptions{}) - if err != nil { - t.Fatalf("NewMountNamespace(): %v", err) - } - - return testutil.NewSystem(ctx, t, k.VFS(), mntns) -} - -// newTestConnection creates a fuse connection that the sentry can communicate with -// and the FD for the server to communicate with. -func newTestConnection(system *testutil.System, k *kernel.Kernel, maxActiveRequests uint64) (*connection, *vfs.FileDescription, error) { - vfsObj := &vfs.VirtualFilesystem{} - fuseDev := &DeviceFD{} - - if err := vfsObj.Init(system.Ctx); err != nil { - return nil, nil, err - } - - vd := vfsObj.NewAnonVirtualDentry("genCountFD") - defer vd.DecRef(system.Ctx) - if err := fuseDev.vfsfd.Init(fuseDev, linux.O_RDWR|linux.O_CREAT, vd.Mount(), vd.Dentry(), &vfs.FileDescriptionOptions{}); err != nil { - return nil, nil, err - } - - fsopts := filesystemOptions{ - maxActiveRequests: maxActiveRequests, - } - fs, err := NewFUSEFilesystem(system.Ctx, 0, &fsopts, &fuseDev.vfsfd) - if err != nil { - return nil, nil, err - } - - return fs.conn, &fuseDev.vfsfd, nil -} - -// SizeBytes implements marshal.Marshallable.SizeBytes. -func (t *testPayload) SizeBytes() int { - return 4 -} - -// MarshalBytes implements marshal.Marshallable.MarshalBytes. -func (t *testPayload) MarshalBytes(dst []byte) { - usermem.ByteOrder.PutUint32(dst[:4], t.data) -} - -// UnmarshalBytes implements marshal.Marshallable.UnmarshalBytes. -func (t *testPayload) UnmarshalBytes(src []byte) { - *t = testPayload{data: usermem.ByteOrder.Uint32(src[:4])} -} - -// Packed implements marshal.Marshallable.Packed. -func (t *testPayload) Packed() bool { - return true -} - -// MarshalUnsafe implements marshal.Marshallable.MarshalUnsafe. -func (t *testPayload) MarshalUnsafe(dst []byte) { - t.MarshalBytes(dst) -} - -// UnmarshalUnsafe implements marshal.Marshallable.UnmarshalUnsafe. -func (t *testPayload) UnmarshalUnsafe(src []byte) { - t.UnmarshalBytes(src) -} - -// CopyOutN implements marshal.Marshallable.CopyOutN. -func (t *testPayload) CopyOutN(task marshal.Task, addr usermem.Addr, limit int) (int, error) { - panic("not implemented") -} - -// CopyOut implements marshal.Marshallable.CopyOut. -func (t *testPayload) CopyOut(task marshal.Task, addr usermem.Addr) (int, error) { - panic("not implemented") -} - -// CopyIn implements marshal.Marshallable.CopyIn. -func (t *testPayload) CopyIn(task marshal.Task, addr usermem.Addr) (int, error) { - panic("not implemented") -} - -// WriteTo implements io.WriterTo.WriteTo. -func (t *testPayload) WriteTo(w io.Writer) (int64, error) { - panic("not implemented") -} diff --git a/pkg/sentry/fsimpl/fuse/fuse_state_autogen.go b/pkg/sentry/fsimpl/fuse/fuse_state_autogen.go new file mode 100644 index 000000000..f72fe342e --- /dev/null +++ b/pkg/sentry/fsimpl/fuse/fuse_state_autogen.go @@ -0,0 +1,184 @@ +// automatically generated by stateify. + +package fuse + +import ( + "gvisor.dev/gvisor/pkg/state" +) + +func (x *Request) StateTypeName() string { + return "pkg/sentry/fsimpl/fuse.Request" +} + +func (x *Request) StateFields() []string { + return []string{ + "requestEntry", + "id", + "hdr", + "data", + } +} + +func (x *Request) beforeSave() {} + +func (x *Request) StateSave(m state.Sink) { + x.beforeSave() + m.Save(0, &x.requestEntry) + m.Save(1, &x.id) + m.Save(2, &x.hdr) + m.Save(3, &x.data) +} + +func (x *Request) afterLoad() {} + +func (x *Request) StateLoad(m state.Source) { + m.Load(0, &x.requestEntry) + m.Load(1, &x.id) + m.Load(2, &x.hdr) + m.Load(3, &x.data) +} + +func (x *Response) StateTypeName() string { + return "pkg/sentry/fsimpl/fuse.Response" +} + +func (x *Response) StateFields() []string { + return []string{ + "opcode", + "hdr", + "data", + } +} + +func (x *Response) beforeSave() {} + +func (x *Response) StateSave(m state.Sink) { + x.beforeSave() + m.Save(0, &x.opcode) + m.Save(1, &x.hdr) + m.Save(2, &x.data) +} + +func (x *Response) afterLoad() {} + +func (x *Response) StateLoad(m state.Source) { + m.Load(0, &x.opcode) + m.Load(1, &x.hdr) + m.Load(2, &x.data) +} + +func (x *futureResponse) StateTypeName() string { + return "pkg/sentry/fsimpl/fuse.futureResponse" +} + +func (x *futureResponse) StateFields() []string { + return []string{ + "opcode", + "ch", + "hdr", + "data", + } +} + +func (x *futureResponse) beforeSave() {} + +func (x *futureResponse) StateSave(m state.Sink) { + x.beforeSave() + m.Save(0, &x.opcode) + m.Save(1, &x.ch) + m.Save(2, &x.hdr) + m.Save(3, &x.data) +} + +func (x *futureResponse) afterLoad() {} + +func (x *futureResponse) StateLoad(m state.Source) { + m.Load(0, &x.opcode) + m.Load(1, &x.ch) + m.Load(2, &x.hdr) + m.Load(3, &x.data) +} + +func (x *inodeRefs) StateTypeName() string { + return "pkg/sentry/fsimpl/fuse.inodeRefs" +} + +func (x *inodeRefs) StateFields() []string { + return []string{ + "refCount", + } +} + +func (x *inodeRefs) beforeSave() {} + +func (x *inodeRefs) StateSave(m state.Sink) { + x.beforeSave() + m.Save(0, &x.refCount) +} + +func (x *inodeRefs) afterLoad() {} + +func (x *inodeRefs) StateLoad(m state.Source) { + m.Load(0, &x.refCount) +} + +func (x *requestList) StateTypeName() string { + return "pkg/sentry/fsimpl/fuse.requestList" +} + +func (x *requestList) StateFields() []string { + return []string{ + "head", + "tail", + } +} + +func (x *requestList) beforeSave() {} + +func (x *requestList) StateSave(m state.Sink) { + x.beforeSave() + m.Save(0, &x.head) + m.Save(1, &x.tail) +} + +func (x *requestList) afterLoad() {} + +func (x *requestList) StateLoad(m state.Source) { + m.Load(0, &x.head) + m.Load(1, &x.tail) +} + +func (x *requestEntry) StateTypeName() string { + return "pkg/sentry/fsimpl/fuse.requestEntry" +} + +func (x *requestEntry) StateFields() []string { + return []string{ + "next", + "prev", + } +} + +func (x *requestEntry) beforeSave() {} + +func (x *requestEntry) StateSave(m state.Sink) { + x.beforeSave() + m.Save(0, &x.next) + m.Save(1, &x.prev) +} + +func (x *requestEntry) afterLoad() {} + +func (x *requestEntry) StateLoad(m state.Source) { + m.Load(0, &x.next) + m.Load(1, &x.prev) +} + +func init() { + state.Register((*Request)(nil)) + state.Register((*Response)(nil)) + state.Register((*futureResponse)(nil)) + state.Register((*inodeRefs)(nil)) + state.Register((*requestList)(nil)) + state.Register((*requestEntry)(nil)) +} diff --git a/pkg/sentry/fsimpl/fuse/inode_refs.go b/pkg/sentry/fsimpl/fuse/inode_refs.go new file mode 100644 index 000000000..5d1de6067 --- /dev/null +++ b/pkg/sentry/fsimpl/fuse/inode_refs.go @@ -0,0 +1,118 @@ +package fuse + +import ( + "runtime" + "sync/atomic" + + "fmt" + "gvisor.dev/gvisor/pkg/log" + refs_vfs1 "gvisor.dev/gvisor/pkg/refs" +) + +// ownerType is used to customize logging. Note that we use a pointer to T so +// that we do not copy the entire object when passed as a format parameter. +var inodeownerType *inode + +// Refs implements refs.RefCounter. It keeps a reference count using atomic +// operations and calls the destructor when the count reaches zero. +// +// Note that the number of references is actually refCount + 1 so that a default +// zero-value Refs object contains one reference. +// +// TODO(gvisor.dev/issue/1486): Store stack traces when leak check is enabled in +// a map with 16-bit hashes, and store the hash in the top 16 bits of refCount. +// This will allow us to add stack trace information to the leak messages +// without growing the size of Refs. +// +// +stateify savable +type inodeRefs struct { + // refCount is composed of two fields: + // + // [32-bit speculative references]:[32-bit real references] + // + // Speculative references are used for TryIncRef, to avoid a CompareAndSwap + // loop. See IncRef, DecRef and TryIncRef for details of how these fields are + // used. + refCount int64 +} + +func (r *inodeRefs) finalize() { + var note string + switch refs_vfs1.GetLeakMode() { + case refs_vfs1.NoLeakChecking: + return + case refs_vfs1.UninitializedLeakChecking: + note = "(Leak checker uninitialized): " + } + if n := r.ReadRefs(); n != 0 { + log.Warningf("%sRefs %p owned by %T garbage collected with ref count of %d (want 0)", note, r, inodeownerType, n) + } +} + +// EnableLeakCheck checks for reference leaks when Refs gets garbage collected. +func (r *inodeRefs) EnableLeakCheck() { + if refs_vfs1.GetLeakMode() != refs_vfs1.NoLeakChecking { + runtime.SetFinalizer(r, (*inodeRefs).finalize) + } +} + +// ReadRefs returns the current number of references. The returned count is +// inherently racy and is unsafe to use without external synchronization. +func (r *inodeRefs) ReadRefs() int64 { + + return atomic.LoadInt64(&r.refCount) + 1 +} + +// IncRef implements refs.RefCounter.IncRef. +// +//go:nosplit +func (r *inodeRefs) IncRef() { + if v := atomic.AddInt64(&r.refCount, 1); v <= 0 { + panic(fmt.Sprintf("Incrementing non-positive ref count %p owned by %T", r, inodeownerType)) + } +} + +// TryIncRef implements refs.RefCounter.TryIncRef. +// +// To do this safely without a loop, a speculative reference is first acquired +// on the object. This allows multiple concurrent TryIncRef calls to distinguish +// other TryIncRef calls from genuine references held. +// +//go:nosplit +func (r *inodeRefs) TryIncRef() bool { + const speculativeRef = 1 << 32 + v := atomic.AddInt64(&r.refCount, speculativeRef) + if int32(v) < 0 { + + atomic.AddInt64(&r.refCount, -speculativeRef) + return false + } + + atomic.AddInt64(&r.refCount, -speculativeRef+1) + return true +} + +// DecRef implements refs.RefCounter.DecRef. +// +// Note that speculative references are counted here. Since they were added +// prior to real references reaching zero, they will successfully convert to +// real references. In other words, we see speculative references only in the +// following case: +// +// A: TryIncRef [speculative increase => sees non-negative references] +// B: DecRef [real decrease] +// A: TryIncRef [transform speculative to real] +// +//go:nosplit +func (r *inodeRefs) DecRef(destroy func()) { + switch v := atomic.AddInt64(&r.refCount, -1); { + case v < -1: + panic(fmt.Sprintf("Decrementing non-positive ref count %p, owned by %T", r, inodeownerType)) + + case v == -1: + + if destroy != nil { + destroy() + } + } +} diff --git a/pkg/sentry/fsimpl/fuse/request_list.go b/pkg/sentry/fsimpl/fuse/request_list.go new file mode 100644 index 000000000..002262f23 --- /dev/null +++ b/pkg/sentry/fsimpl/fuse/request_list.go @@ -0,0 +1,193 @@ +package fuse + +// ElementMapper provides an identity mapping by default. +// +// This can be replaced to provide a struct that maps elements to linker +// objects, if they are not the same. An ElementMapper is not typically +// required if: Linker is left as is, Element is left as is, or Linker and +// Element are the same type. +type requestElementMapper struct{} + +// linkerFor maps an Element to a Linker. +// +// This default implementation should be inlined. +// +//go:nosplit +func (requestElementMapper) linkerFor(elem *Request) *Request { return elem } + +// List is an intrusive list. Entries can be added to or removed from the list +// in O(1) time and with no additional memory allocations. +// +// The zero value for List is an empty list ready to use. +// +// To iterate over a list (where l is a List): +// for e := l.Front(); e != nil; e = e.Next() { +// // do something with e. +// } +// +// +stateify savable +type requestList struct { + head *Request + tail *Request +} + +// Reset resets list l to the empty state. +func (l *requestList) Reset() { + l.head = nil + l.tail = nil +} + +// Empty returns true iff the list is empty. +func (l *requestList) Empty() bool { + return l.head == nil +} + +// Front returns the first element of list l or nil. +func (l *requestList) Front() *Request { + return l.head +} + +// Back returns the last element of list l or nil. +func (l *requestList) Back() *Request { + return l.tail +} + +// Len returns the number of elements in the list. +// +// NOTE: This is an O(n) operation. +func (l *requestList) Len() (count int) { + for e := l.Front(); e != nil; e = (requestElementMapper{}.linkerFor(e)).Next() { + count++ + } + return count +} + +// PushFront inserts the element e at the front of list l. +func (l *requestList) PushFront(e *Request) { + linker := requestElementMapper{}.linkerFor(e) + linker.SetNext(l.head) + linker.SetPrev(nil) + if l.head != nil { + requestElementMapper{}.linkerFor(l.head).SetPrev(e) + } else { + l.tail = e + } + + l.head = e +} + +// PushBack inserts the element e at the back of list l. +func (l *requestList) PushBack(e *Request) { + linker := requestElementMapper{}.linkerFor(e) + linker.SetNext(nil) + linker.SetPrev(l.tail) + if l.tail != nil { + requestElementMapper{}.linkerFor(l.tail).SetNext(e) + } else { + l.head = e + } + + l.tail = e +} + +// PushBackList inserts list m at the end of list l, emptying m. +func (l *requestList) PushBackList(m *requestList) { + if l.head == nil { + l.head = m.head + l.tail = m.tail + } else if m.head != nil { + requestElementMapper{}.linkerFor(l.tail).SetNext(m.head) + requestElementMapper{}.linkerFor(m.head).SetPrev(l.tail) + + l.tail = m.tail + } + m.head = nil + m.tail = nil +} + +// InsertAfter inserts e after b. +func (l *requestList) InsertAfter(b, e *Request) { + bLinker := requestElementMapper{}.linkerFor(b) + eLinker := requestElementMapper{}.linkerFor(e) + + a := bLinker.Next() + + eLinker.SetNext(a) + eLinker.SetPrev(b) + bLinker.SetNext(e) + + if a != nil { + requestElementMapper{}.linkerFor(a).SetPrev(e) + } else { + l.tail = e + } +} + +// InsertBefore inserts e before a. +func (l *requestList) InsertBefore(a, e *Request) { + aLinker := requestElementMapper{}.linkerFor(a) + eLinker := requestElementMapper{}.linkerFor(e) + + b := aLinker.Prev() + eLinker.SetNext(a) + eLinker.SetPrev(b) + aLinker.SetPrev(e) + + if b != nil { + requestElementMapper{}.linkerFor(b).SetNext(e) + } else { + l.head = e + } +} + +// Remove removes e from l. +func (l *requestList) Remove(e *Request) { + linker := requestElementMapper{}.linkerFor(e) + prev := linker.Prev() + next := linker.Next() + + if prev != nil { + requestElementMapper{}.linkerFor(prev).SetNext(next) + } else if l.head == e { + l.head = next + } + + if next != nil { + requestElementMapper{}.linkerFor(next).SetPrev(prev) + } else if l.tail == e { + l.tail = prev + } + + linker.SetNext(nil) + linker.SetPrev(nil) +} + +// Entry is a default implementation of Linker. Users can add anonymous fields +// of this type to their structs to make them automatically implement the +// methods needed by List. +// +// +stateify savable +type requestEntry struct { + next *Request + prev *Request +} + +// Next returns the entry that follows e in the list. +func (e *requestEntry) Next() *Request { + return e.next +} + +// Prev returns the entry that precedes e in the list. +func (e *requestEntry) Prev() *Request { + return e.prev +} + +// SetNext assigns 'entry' as the entry that follows e in the list. +func (e *requestEntry) SetNext(elem *Request) { + e.next = elem +} + +// SetPrev assigns 'entry' as the entry that precedes e in the list. +func (e *requestEntry) SetPrev(elem *Request) { + e.prev = elem +} |