diff options
Diffstat (limited to 'pkg/sentry/kernel')
| -rw-r--r-- | pkg/sentry/kernel/BUILD | 2 | ||||
| -rw-r--r-- | pkg/sentry/kernel/fd_table.go | 196 | ||||
| -rw-r--r-- | pkg/sentry/kernel/fd_table_unsafe.go | 11 | ||||
| -rw-r--r-- | pkg/sentry/kernel/ipc/BUILD | 20 | ||||
| -rw-r--r-- | pkg/sentry/kernel/ipc/object.go | 115 | ||||
| -rw-r--r-- | pkg/sentry/kernel/ipc/registry.go | 196 | ||||
| -rw-r--r-- | pkg/sentry/kernel/ipc_namespace.go | 8 | ||||
| -rw-r--r-- | pkg/sentry/kernel/msgqueue/BUILD | 36 | ||||
| -rw-r--r-- | pkg/sentry/kernel/msgqueue/msgqueue.go | 220 | ||||
| -rw-r--r-- | pkg/sentry/kernel/ptrace.go | 6 | ||||
| -rw-r--r-- | pkg/sentry/kernel/semaphore/BUILD | 13 | ||||
| -rw-r--r-- | pkg/sentry/kernel/semaphore/semaphore.go | 256 | ||||
| -rw-r--r-- | pkg/sentry/kernel/semaphore/semaphore_test.go | 20 | ||||
| -rw-r--r-- | pkg/sentry/kernel/shm/BUILD | 1 | ||||
| -rw-r--r-- | pkg/sentry/kernel/shm/shm.go | 259 | ||||
| -rw-r--r-- | pkg/sentry/kernel/task_clone.go | 233 |
16 files changed, 986 insertions, 606 deletions
diff --git a/pkg/sentry/kernel/BUILD b/pkg/sentry/kernel/BUILD index 26614b029..e4e0dc04f 100644 --- a/pkg/sentry/kernel/BUILD +++ b/pkg/sentry/kernel/BUILD @@ -220,6 +220,7 @@ go_library( "//pkg/abi/linux", "//pkg/abi/linux/errno", "//pkg/amutex", + "//pkg/bitmap", "//pkg/bits", "//pkg/bpf", "//pkg/cleanup", @@ -256,6 +257,7 @@ go_library( "//pkg/sentry/kernel/auth", "//pkg/sentry/kernel/epoll", "//pkg/sentry/kernel/futex", + "//pkg/sentry/kernel/msgqueue", "//pkg/sentry/kernel/sched", "//pkg/sentry/kernel/semaphore", "//pkg/sentry/kernel/shm", diff --git a/pkg/sentry/kernel/fd_table.go b/pkg/sentry/kernel/fd_table.go index 8786a70b5..eff556a0c 100644 --- a/pkg/sentry/kernel/fd_table.go +++ b/pkg/sentry/kernel/fd_table.go @@ -18,10 +18,10 @@ import ( "fmt" "math" "strings" - "sync/atomic" "golang.org/x/sys/unix" "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/bitmap" "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/errors/linuxerr" "gvisor.dev/gvisor/pkg/sentry/fs" @@ -84,13 +84,8 @@ type FDTable struct { // mu protects below. mu sync.Mutex `state:"nosave"` - // next is start position to find fd. - next int32 - - // used contains the number of non-nil entries. It must be accessed - // atomically. It may be read atomically without holding mu (but not - // written). - used int32 + // fdBitmap shows which fds are already in use. + fdBitmap bitmap.Bitmap `state:"nosave"` // descriptorTable holds descriptors. descriptorTable `state:".(map[int32]descriptor)"` @@ -98,6 +93,8 @@ type FDTable struct { func (f *FDTable) saveDescriptorTable() map[int32]descriptor { m := make(map[int32]descriptor) + f.mu.Lock() + defer f.mu.Unlock() f.forEach(context.Background(), func(fd int32, file *fs.File, fileVFS2 *vfs.FileDescription, flags FDFlags) { m[fd] = descriptor{ file: file, @@ -111,12 +108,16 @@ func (f *FDTable) saveDescriptorTable() map[int32]descriptor { func (f *FDTable) loadDescriptorTable(m map[int32]descriptor) { ctx := context.Background() f.initNoLeakCheck() // Initialize table. - f.used = 0 + f.fdBitmap = bitmap.New(uint32(math.MaxUint16)) for fd, d := range m { + if fd < 0 { + panic(fmt.Sprintf("FD is not supposed to be negative. FD: %d", fd)) + } + if file, fileVFS2 := f.setAll(ctx, fd, d.file, d.fileVFS2, d.flags); file != nil || fileVFS2 != nil { panic("VFS1 or VFS2 files set") } - + f.fdBitmap.Add(uint32(fd)) // Note that we do _not_ need to acquire a extra table reference here. The // table reference will already be accounted for in the file, so we drop the // reference taken by set above. @@ -189,8 +190,10 @@ func (f *FDTable) DecRef(ctx context.Context) { func (f *FDTable) forEach(ctx context.Context, fn func(fd int32, file *fs.File, fileVFS2 *vfs.FileDescription, flags FDFlags)) { // retries tracks the number of failed TryIncRef attempts for the same FD. retries := 0 - fd := int32(0) - for { + fds := f.fdBitmap.ToSlice() + // Iterate through the fdBitmap. + for _, ufd := range fds { + fd := int32(ufd) file, fileVFS2, flags, ok := f.getAll(fd) if !ok { break @@ -218,7 +221,6 @@ func (f *FDTable) forEach(ctx context.Context, fn func(fd int32, file *fs.File, fileVFS2.DecRef(ctx) } retries = 0 - fd++ } } @@ -226,6 +228,8 @@ func (f *FDTable) forEach(ctx context.Context, fn func(fd int32, file *fs.File, func (f *FDTable) String() string { var buf strings.Builder ctx := context.Background() + f.mu.Lock() + defer f.mu.Unlock() f.forEach(ctx, func(fd int32, file *fs.File, fileVFS2 *vfs.FileDescription, flags FDFlags) { switch { case file != nil: @@ -250,10 +254,10 @@ func (f *FDTable) String() string { } // NewFDs allocates new FDs guaranteed to be the lowest number available -// greater than or equal to the fd parameter. All files will share the set +// greater than or equal to the minFD parameter. All files will share the set // flags. Success is guaranteed to be all or none. -func (f *FDTable) NewFDs(ctx context.Context, fd int32, files []*fs.File, flags FDFlags) (fds []int32, err error) { - if fd < 0 { +func (f *FDTable) NewFDs(ctx context.Context, minFD int32, files []*fs.File, flags FDFlags) (fds []int32, err error) { + if minFD < 0 { // Don't accept negative FDs. return nil, unix.EINVAL } @@ -267,31 +271,48 @@ func (f *FDTable) NewFDs(ctx context.Context, fd int32, files []*fs.File, flags if lim.Cur != limits.Infinity { end = int32(lim.Cur) } - if fd >= end { + if minFD+int32(len(files)) > end { return nil, unix.EMFILE } } f.mu.Lock() - // From f.next to find available fd. - if fd < f.next { - fd = f.next + // max is used as the largest number in fdBitmap + 1. + max := int32(0) + + if !f.fdBitmap.IsEmpty() { + max = int32(f.fdBitmap.Maximum()) + max++ } + // Adjust max in case it is less than minFD. + if max < minFD { + max = minFD + } // Install all entries. - for i := fd; i < end && len(fds) < len(files); i++ { - if d, _, _ := f.get(i); d == nil { - // Set the descriptor. - f.set(ctx, i, files[len(fds)], flags) - fds = append(fds, i) // Record the file descriptor. + for len(fds) < len(files) { + // Try to use free bit in fdBitmap. + // If all bits in fdBitmap are used, expand fd to the max. + fd := f.fdBitmap.FirstZero(uint32(minFD)) + if fd == math.MaxInt32 { + fd = uint32(max) + max++ + } + if fd >= uint32(end) { + break } + f.fdBitmap.Add(fd) + f.set(ctx, int32(fd), files[len(fds)], flags) + fds = append(fds, int32(fd)) + minFD = int32(fd) } // Failure? Unwind existing FDs. if len(fds) < len(files) { for _, i := range fds { f.set(ctx, i, nil, FDFlags{}) + f.fdBitmap.Remove(uint32(i)) } f.mu.Unlock() @@ -305,20 +326,15 @@ func (f *FDTable) NewFDs(ctx context.Context, fd int32, files []*fs.File, flags return nil, unix.EMFILE } - if fd == f.next { - // Update next search start position. - f.next = fds[len(fds)-1] + 1 - } - f.mu.Unlock() return fds, nil } // NewFDsVFS2 allocates new FDs guaranteed to be the lowest number available -// greater than or equal to the fd parameter. All files will share the set +// greater than or equal to the minFD parameter. All files will share the set // flags. Success is guaranteed to be all or none. -func (f *FDTable) NewFDsVFS2(ctx context.Context, fd int32, files []*vfs.FileDescription, flags FDFlags) (fds []int32, err error) { - if fd < 0 { +func (f *FDTable) NewFDsVFS2(ctx context.Context, minFD int32, files []*vfs.FileDescription, flags FDFlags) (fds []int32, err error) { + if minFD < 0 { // Don't accept negative FDs. return nil, unix.EINVAL } @@ -332,31 +348,47 @@ func (f *FDTable) NewFDsVFS2(ctx context.Context, fd int32, files []*vfs.FileDes if lim.Cur != limits.Infinity { end = int32(lim.Cur) } - if fd >= end { + if minFD >= end { return nil, unix.EMFILE } } f.mu.Lock() - // From f.next to find available fd. - if fd < f.next { - fd = f.next + // max is used as the largest number in fdBitmap + 1. + max := int32(0) + + if !f.fdBitmap.IsEmpty() { + max = int32(f.fdBitmap.Maximum()) + max++ } - // Install all entries. - for i := fd; i < end && len(fds) < len(files); i++ { - if d, _, _ := f.getVFS2(i); d == nil { - // Set the descriptor. - f.setVFS2(ctx, i, files[len(fds)], flags) - fds = append(fds, i) // Record the file descriptor. - } + // Adjust max in case it is less than minFD. + if max < minFD { + max = minFD } + for len(fds) < len(files) { + // Try to use free bit in fdBitmap. + // If all bits in fdBitmap are used, expand fd to the max. + fd := f.fdBitmap.FirstZero(uint32(minFD)) + if fd == math.MaxInt32 { + fd = uint32(max) + max++ + } + if fd >= uint32(end) { + break + } + f.fdBitmap.Add(fd) + f.setVFS2(ctx, int32(fd), files[len(fds)], flags) + fds = append(fds, int32(fd)) + minFD = int32(fd) + } // Failure? Unwind existing FDs. if len(fds) < len(files) { for _, i := range fds { f.setVFS2(ctx, i, nil, FDFlags{}) + f.fdBitmap.Remove(uint32(i)) } f.mu.Unlock() @@ -370,57 +402,19 @@ func (f *FDTable) NewFDsVFS2(ctx context.Context, fd int32, files []*vfs.FileDes return nil, unix.EMFILE } - if fd == f.next { - // Update next search start position. - f.next = fds[len(fds)-1] + 1 - } - f.mu.Unlock() return fds, nil } -// NewFDVFS2 allocates a file descriptor greater than or equal to minfd for +// NewFDVFS2 allocates a file descriptor greater than or equal to minFD for // the given file description. If it succeeds, it takes a reference on file. -func (f *FDTable) NewFDVFS2(ctx context.Context, minfd int32, file *vfs.FileDescription, flags FDFlags) (int32, error) { - if minfd < 0 { - // Don't accept negative FDs. - return -1, unix.EINVAL - } - - // Default limit. - end := int32(math.MaxInt32) - - // Ensure we don't get past the provided limit. - if limitSet := limits.FromContext(ctx); limitSet != nil { - lim := limitSet.Get(limits.NumberOfFiles) - if lim.Cur != limits.Infinity { - end = int32(lim.Cur) - } - if minfd >= end { - return -1, unix.EMFILE - } - } - - f.mu.Lock() - defer f.mu.Unlock() - - // From f.next to find available fd. - fd := minfd - if fd < f.next { - fd = f.next - } - for fd < end { - if d, _, _ := f.getVFS2(fd); d == nil { - f.setVFS2(ctx, fd, file, flags) - if fd == f.next { - // Update next search start position. - f.next = fd + 1 - } - return fd, nil - } - fd++ +func (f *FDTable) NewFDVFS2(ctx context.Context, minFD int32, file *vfs.FileDescription, flags FDFlags) (int32, error) { + files := []*vfs.FileDescription{file} + fileSlice, error := f.NewFDsVFS2(ctx, minFD, files, flags) + if error != nil { + return -1, error } - return -1, unix.EMFILE + return fileSlice[0], nil } // NewFDAt sets the file reference for the given FD. If there is an active @@ -469,6 +463,11 @@ func (f *FDTable) newFDAt(ctx context.Context, fd int32, file *fs.File, fileVFS2 defer f.mu.Unlock() df, dfVFS2 := f.setAll(ctx, fd, file, fileVFS2, flags) + // Add fd to fdBitmap. + if file != nil || fileVFS2 != nil { + f.fdBitmap.Add(uint32(fd)) + } + return df, dfVFS2, nil } @@ -573,7 +572,9 @@ func (f *FDTable) GetVFS2(fd int32) (*vfs.FileDescription, FDFlags) { // Precondition: The caller must be running on the task goroutine, or Task.mu // must be locked. func (f *FDTable) GetFDs(ctx context.Context) []int32 { - fds := make([]int32, 0, int(atomic.LoadInt32(&f.used))) + f.mu.Lock() + defer f.mu.Unlock() + fds := make([]int32, 0, int(f.fdBitmap.GetNumOnes())) f.forEach(ctx, func(fd int32, _ *fs.File, _ *vfs.FileDescription, _ FDFlags) { fds = append(fds, fd) }) @@ -583,13 +584,15 @@ func (f *FDTable) GetFDs(ctx context.Context) []int32 { // Fork returns an independent FDTable. func (f *FDTable) Fork(ctx context.Context) *FDTable { clone := f.k.NewFDTable() - + f.mu.Lock() + defer f.mu.Unlock() f.forEach(ctx, func(fd int32, file *fs.File, fileVFS2 *vfs.FileDescription, flags FDFlags) { // The set function here will acquire an appropriate table // reference for the clone. We don't need anything else. if df, dfVFS2 := clone.setAll(ctx, fd, file, fileVFS2, flags); df != nil || dfVFS2 != nil { panic("VFS1 or VFS2 files set") } + clone.fdBitmap.Add(uint32(fd)) }) return clone } @@ -604,11 +607,6 @@ func (f *FDTable) Remove(ctx context.Context, fd int32) (*fs.File, *vfs.FileDesc f.mu.Lock() - // Update current available position. - if fd < f.next { - f.next = fd - } - orig, orig2, _, _ := f.getAll(fd) // Add reference for caller. @@ -621,6 +619,7 @@ func (f *FDTable) Remove(ctx context.Context, fd int32) (*fs.File, *vfs.FileDesc if orig != nil || orig2 != nil { orig, orig2 = f.setAll(ctx, fd, nil, nil, FDFlags{}) // Zap entry. + f.fdBitmap.Remove(uint32(fd)) } f.mu.Unlock() @@ -644,16 +643,13 @@ func (f *FDTable) RemoveIf(ctx context.Context, cond func(*fs.File, *vfs.FileDes f.forEach(ctx, func(fd int32, file *fs.File, fileVFS2 *vfs.FileDescription, flags FDFlags) { if cond(file, fileVFS2, flags) { df, dfVFS2 := f.setAll(ctx, fd, nil, nil, FDFlags{}) // Clear from table. + f.fdBitmap.Remove(uint32(fd)) if df != nil { files = append(files, df) } if dfVFS2 != nil { filesVFS2 = append(filesVFS2, dfVFS2) } - // Update current available position. - if fd < f.next { - f.next = fd - } } }) f.mu.Unlock() diff --git a/pkg/sentry/kernel/fd_table_unsafe.go b/pkg/sentry/kernel/fd_table_unsafe.go index f17f9c59c..2b3e6ef71 100644 --- a/pkg/sentry/kernel/fd_table_unsafe.go +++ b/pkg/sentry/kernel/fd_table_unsafe.go @@ -15,9 +15,11 @@ package kernel import ( + "math" "sync/atomic" "unsafe" + "gvisor.dev/gvisor/pkg/bitmap" "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/sentry/fs" "gvisor.dev/gvisor/pkg/sentry/vfs" @@ -44,6 +46,7 @@ func (f *FDTable) initNoLeakCheck() { func (f *FDTable) init() { f.initNoLeakCheck() f.InitRefs() + f.fdBitmap = bitmap.New(uint32(math.MaxUint16)) } // get gets a file entry. @@ -162,14 +165,6 @@ func (f *FDTable) setAll(ctx context.Context, fd int32, file *fs.File, fileVFS2 } } - // Adjust used. - switch { - case orig == nil && desc != nil: - atomic.AddInt32(&f.used, 1) - case orig != nil && desc == nil: - atomic.AddInt32(&f.used, -1) - } - if orig != nil { switch { case orig.file != nil: diff --git a/pkg/sentry/kernel/ipc/BUILD b/pkg/sentry/kernel/ipc/BUILD new file mode 100644 index 000000000..e42a94e15 --- /dev/null +++ b/pkg/sentry/kernel/ipc/BUILD @@ -0,0 +1,20 @@ +load("//tools:defs.bzl", "go_library") + +package(licenses = ["notice"]) + +go_library( + name = "ipc", + srcs = [ + "object.go", + "registry.go", + ], + visibility = ["//pkg/sentry:internal"], + deps = [ + "//pkg/abi/linux", + "//pkg/context", + "//pkg/errors/linuxerr", + "//pkg/log", + "//pkg/sentry/fs", + "//pkg/sentry/kernel/auth", + ], +) diff --git a/pkg/sentry/kernel/ipc/object.go b/pkg/sentry/kernel/ipc/object.go new file mode 100644 index 000000000..387b35e7e --- /dev/null +++ b/pkg/sentry/kernel/ipc/object.go @@ -0,0 +1,115 @@ +// Copyright 2021 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 ipc defines functionality and utilities common to sysvipc mechanisms. +// +// Lock ordering: [shm/semaphore/msgqueue].Registry.mu -> Mechanism +package ipc + +import ( + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/sentry/fs" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" +) + +// Key is a user-provided identifier for IPC objects. +type Key int32 + +// ID is a kernel identifier for IPC objects. +type ID int32 + +// Object represents an abstract IPC object with fields common to all IPC +// mechanisms. +// +// +stateify savable +type Object struct { + // User namespace which owns the IPC namespace which owns the IPC object. + // Immutable. + UserNS *auth.UserNamespace + + // ID is a kernel identifier for the IPC object. Immutable. + ID ID + + // Key is a user-provided identifier for the IPC object. Immutable. + Key Key + + // Creator is the user who created the IPC object. Immutable. + Creator fs.FileOwner + + // Owner is the current owner of the IPC object. + Owner fs.FileOwner + + // Perms is the access permissions the IPC object. + Perms fs.FilePermissions +} + +// Mechanism represents a SysV mechanism that holds an IPC object. It can also +// be looked at as a container for an ipc.Object, which is by definition a fully +// functional SysV object. +type Mechanism interface { + // Lock behaves the same as Mutex.Lock on the mechanism. + Lock() + + // Unlock behaves the same as Mutex.Unlock on the mechanism. + Unlock() + + // Object returns a pointer to the mechanism's ipc.Object. Mechanism.Lock, + // and Mechanism.Unlock should be used when the object is used. + Object() *Object + + // Destroy destroys the mechanism. + Destroy() +} + +// NewObject returns a new, initialized ipc.Object. The newly returned object +// doesn't have a valid ID. When the object is registered, the registry assigns +// it a new unique ID. +func NewObject(un *auth.UserNamespace, key Key, creator, owner fs.FileOwner, perms fs.FilePermissions) *Object { + return &Object{ + UserNS: un, + Key: key, + Creator: creator, + Owner: owner, + Perms: perms, + } +} + +// CheckOwnership verifies whether an IPC object may be accessed using creds as +// an owner. See ipc/util.c:ipcctl_obtain_check() in Linux. +func (o *Object) CheckOwnership(creds *auth.Credentials) bool { + if o.Owner.UID == creds.EffectiveKUID || o.Creator.UID == creds.EffectiveKUID { + return true + } + + // Tasks with CAP_SYS_ADMIN may bypass ownership checks. Strangely, Linux + // doesn't use CAP_IPC_OWNER for this despite CAP_IPC_OWNER being documented + // for use to "override IPC ownership checks". + return creds.HasCapabilityIn(linux.CAP_SYS_ADMIN, o.UserNS) +} + +// CheckPermissions verifies whether an IPC object is accessible using creds for +// access described by req. See ipc/util.c:ipcperms() in Linux. +func (o *Object) CheckPermissions(creds *auth.Credentials, req fs.PermMask) bool { + p := o.Perms.Other + if o.Owner.UID == creds.EffectiveKUID { + p = o.Perms.User + } else if creds.InGroup(o.Owner.GID) { + p = o.Perms.Group + } + + if p.SupersetOf(req) { + return true + } + return creds.HasCapabilityIn(linux.CAP_IPC_OWNER, o.UserNS) +} diff --git a/pkg/sentry/kernel/ipc/registry.go b/pkg/sentry/kernel/ipc/registry.go new file mode 100644 index 000000000..91de19070 --- /dev/null +++ b/pkg/sentry/kernel/ipc/registry.go @@ -0,0 +1,196 @@ +// Copyright 2021 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 ipc + +import ( + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/errors/linuxerr" + "gvisor.dev/gvisor/pkg/log" + "gvisor.dev/gvisor/pkg/sentry/fs" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" +) + +// Registry is similar to Object, but for registries. It represent an abstract +// SysV IPC registry with fields common to all SysV registries. Registry is not +// thread-safe, and should be protected using a mutex. +// +// +stateify savable +type Registry struct { + // UserNS owning the IPC namespace this registry belongs to. Immutable. + UserNS *auth.UserNamespace + + // objects is a map of IDs to IPC mechanisms. + objects map[ID]Mechanism + + // KeysToIDs maps a lookup key to an ID. + keysToIDs map[Key]ID + + // lastIDUsed is used to find the next available ID for object creation. + lastIDUsed ID +} + +// NewRegistry return a new, initialized ipc.Registry. +func NewRegistry(userNS *auth.UserNamespace) *Registry { + return &Registry{ + UserNS: userNS, + objects: make(map[ID]Mechanism), + keysToIDs: make(map[Key]ID), + } +} + +// Find uses key to search for and return a SysV mechanism. Find returns an +// error if an object is found by shouldn't be, or if the user doesn't have +// permission to use the object. If no object is found, Find checks create +// flag, and returns an error only if it's false. +func (r *Registry) Find(ctx context.Context, key Key, mode linux.FileMode, create, exclusive bool) (Mechanism, error) { + if id, ok := r.keysToIDs[key]; ok { + mech := r.objects[id] + mech.Lock() + defer mech.Unlock() + + obj := mech.Object() + creds := auth.CredentialsFromContext(ctx) + if !obj.CheckPermissions(creds, fs.PermsFromMode(mode)) { + // The [calling process / user] does not have permission to access + // the set, and does not have the CAP_IPC_OWNER capability in the + // user namespace that governs its IPC namespace. + return nil, linuxerr.EACCES + } + + if create && exclusive { + // IPC_CREAT and IPC_EXCL were specified, but an object already + // exists for key. + return nil, linuxerr.EEXIST + } + return mech, nil + } + + if !create { + // No object exists for key and msgflg did not specify IPC_CREAT. + return nil, linuxerr.ENOENT + } + + return nil, nil +} + +// Register adds the given object into Registry.Objects, and assigns it a new +// ID. It returns an error if all IDs are exhausted. +func (r *Registry) Register(m Mechanism) error { + id, err := r.newID() + if err != nil { + return err + } + + obj := m.Object() + obj.ID = id + + r.objects[id] = m + r.keysToIDs[obj.Key] = id + + return nil +} + +// newID finds the first unused ID in the registry, and returns an error if +// non is found. +func (r *Registry) newID() (ID, error) { + // Find the next available ID. + for id := r.lastIDUsed + 1; id != r.lastIDUsed; id++ { + // Handle wrap around. + if id < 0 { + id = 0 + continue + } + if r.objects[id] == nil { + r.lastIDUsed = id + return id, nil + } + } + + log.Warningf("ids exhausted, they may be leaking") + + // The man pages for shmget(2) mention that ENOSPC should be used if "All + // possible shared memory IDs have been taken (SHMMNI)". Other SysV + // mechanisms don't have a specific errno for running out of IDs, but they + // return ENOSPC if the max number of objects is exceeded, so we assume that + // it's the same case. + return 0, linuxerr.ENOSPC +} + +// Remove removes the mechanism with the given id from the registry, and calls +// mechanism.Destroy to perform mechanism-specific removal. +func (r *Registry) Remove(id ID, creds *auth.Credentials) error { + mech := r.objects[id] + if mech == nil { + return linuxerr.EINVAL + } + + mech.Lock() + defer mech.Unlock() + + obj := mech.Object() + + // The effective user ID of the calling process must match the creator or + // owner of the [mechanism], or the caller must be privileged. + if !obj.CheckOwnership(creds) { + return linuxerr.EPERM + } + + delete(r.objects, obj.ID) + delete(r.keysToIDs, obj.Key) + mech.Destroy() + + return nil +} + +// ForAllObjects executes a given function for all given objects. +func (r *Registry) ForAllObjects(f func(o Mechanism)) { + for _, o := range r.objects { + f(o) + } +} + +// FindByID returns the mechanism with the given ID, nil if non exists. +func (r *Registry) FindByID(id ID) Mechanism { + return r.objects[id] +} + +// DissociateKey removes the association between a mechanism and its key +// (deletes it from r.keysToIDs), preventing it from being discovered by any new +// process, but not necessarily destroying it. If the given key doesn't exist, +// nothing is changed. +func (r *Registry) DissociateKey(key Key) { + delete(r.keysToIDs, key) +} + +// DissociateID removes the association between a mechanism and its ID (deletes +// it from r.objects). An ID can't be removed unless the associated key is +// removed already, this is done to prevent the users from acquiring nil a +// Mechanism. +// +// Precondition: must be preceded by a call to r.DissociateKey. +func (r *Registry) DissociateID(id ID) { + delete(r.objects, id) +} + +// ObjectCount returns the number of registered objects. +func (r *Registry) ObjectCount() int { + return len(r.objects) +} + +// LastIDUsed returns the last used ID. +func (r *Registry) LastIDUsed() ID { + return r.lastIDUsed +} diff --git a/pkg/sentry/kernel/ipc_namespace.go b/pkg/sentry/kernel/ipc_namespace.go index 9545bb5ef..0b101b1bb 100644 --- a/pkg/sentry/kernel/ipc_namespace.go +++ b/pkg/sentry/kernel/ipc_namespace.go @@ -17,6 +17,7 @@ package kernel import ( "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/kernel/msgqueue" "gvisor.dev/gvisor/pkg/sentry/kernel/semaphore" "gvisor.dev/gvisor/pkg/sentry/kernel/shm" ) @@ -30,6 +31,7 @@ type IPCNamespace struct { // User namespace which owns this IPC namespace. Immutable. userNS *auth.UserNamespace + queues *msgqueue.Registry semaphores *semaphore.Registry shms *shm.Registry } @@ -38,6 +40,7 @@ type IPCNamespace struct { func NewIPCNamespace(userNS *auth.UserNamespace) *IPCNamespace { ns := &IPCNamespace{ userNS: userNS, + queues: msgqueue.NewRegistry(userNS), semaphores: semaphore.NewRegistry(userNS), shms: shm.NewRegistry(userNS), } @@ -45,6 +48,11 @@ func NewIPCNamespace(userNS *auth.UserNamespace) *IPCNamespace { return ns } +// MsgqueueRegistry returns the message queue registry for this namespace. +func (i *IPCNamespace) MsgqueueRegistry() *msgqueue.Registry { + return i.queues +} + // SemaphoreRegistry returns the semaphore set registry for this namespace. func (i *IPCNamespace) SemaphoreRegistry() *semaphore.Registry { return i.semaphores diff --git a/pkg/sentry/kernel/msgqueue/BUILD b/pkg/sentry/kernel/msgqueue/BUILD new file mode 100644 index 000000000..5ec11e1f6 --- /dev/null +++ b/pkg/sentry/kernel/msgqueue/BUILD @@ -0,0 +1,36 @@ +load("//tools:defs.bzl", "go_library") +load("//tools/go_generics:defs.bzl", "go_template_instance") + +package(licenses = ["notice"]) + +go_template_instance( + name = "message_list", + out = "message_list.go", + package = "msgqueue", + prefix = "msg", + template = "//pkg/ilist:generic_list", + types = { + "Element": "*Message", + "Linker": "*Message", + }, +) + +go_library( + name = "msgqueue", + srcs = [ + "message_list.go", + "msgqueue.go", + ], + visibility = ["//pkg/sentry:internal"], + deps = [ + "//pkg/abi/linux", + "//pkg/context", + "//pkg/errors/linuxerr", + "//pkg/sentry/fs", + "//pkg/sentry/kernel/auth", + "//pkg/sentry/kernel/ipc", + "//pkg/sentry/kernel/time", + "//pkg/sync", + "//pkg/waiter", + ], +) diff --git a/pkg/sentry/kernel/msgqueue/msgqueue.go b/pkg/sentry/kernel/msgqueue/msgqueue.go new file mode 100644 index 000000000..3ce926950 --- /dev/null +++ b/pkg/sentry/kernel/msgqueue/msgqueue.go @@ -0,0 +1,220 @@ +// Copyright 2021 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 msgqueue implements System V message queues. +package msgqueue + +import ( + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/errors/linuxerr" + "gvisor.dev/gvisor/pkg/sentry/fs" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/kernel/ipc" + ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time" + "gvisor.dev/gvisor/pkg/sync" + "gvisor.dev/gvisor/pkg/waiter" +) + +const ( + // System-wide limit for maximum number of queues. + maxQueues = linux.MSGMNI + + // Maximum size of a queue in bytes. + maxQueueBytes = linux.MSGMNB + + // Maximum size of a message in bytes. + maxMessageBytes = linux.MSGMAX +) + +// Registry contains a set of message queues that can be referenced using keys +// or IDs. +// +// +stateify savable +type Registry struct { + // mu protects all the fields below. + mu sync.Mutex `state:"nosave"` + + // reg defines basic fields and operations needed for all SysV registries. + reg *ipc.Registry +} + +// NewRegistry returns a new Registry ready to be used. +func NewRegistry(userNS *auth.UserNamespace) *Registry { + return &Registry{ + reg: ipc.NewRegistry(userNS), + } +} + +// Queue represents a SysV message queue, described by sysvipc(7). +// +// +stateify savable +type Queue struct { + // registry is the registry owning this queue. Immutable. + registry *Registry + + // mu protects all the fields below. + mu sync.Mutex `state:"nosave"` + + // dead is set to true when a queue is removed from the registry and should + // not be used. Operations on the queue should check dead, and return + // EIDRM if set to true. + dead bool + + // obj defines basic fields that should be included in all SysV IPC objects. + obj *ipc.Object + + // senders holds a queue of blocked message senders. Senders are notified + // when enough space is available in the queue to insert their message. + senders waiter.Queue + + // receivers holds a queue of blocked receivers. Receivers are notified + // when a new message is inserted into the queue and can be received. + receivers waiter.Queue + + // messages is a list of sent messages. + messages msgList + + // sendTime is the last time a msgsnd was perfomed. + sendTime ktime.Time + + // receiveTime is the last time a msgrcv was performed. + receiveTime ktime.Time + + // changeTime is the last time the queue was modified using msgctl. + changeTime ktime.Time + + // byteCount is the current number of message bytes in the queue. + byteCount uint64 + + // messageCount is the current number of messages in the queue. + messageCount uint64 + + // maxBytes is the maximum allowed number of bytes in the queue, and is also + // used as a limit for the number of total possible messages. + maxBytes uint64 + + // sendPID is the PID of the process that performed the last msgsnd. + sendPID int32 + + // receivePID is the PID of the process that performed the last msgrcv. + receivePID int32 +} + +// Message represents a message exchanged through a Queue via msgsnd(2) and +// msgrcv(2). +// +// +stateify savable +type Message struct { + msgEntry + + // mType is an integer representing the type of the sent message. + mType int64 + + // mText is an untyped block of memory. + mText []byte + + // mSize is the size of mText. + mSize uint64 +} + +// FindOrCreate creates a new message queue or returns an existing one. See +// msgget(2). +func (r *Registry) FindOrCreate(ctx context.Context, key ipc.Key, mode linux.FileMode, private, create, exclusive bool) (*Queue, error) { + r.mu.Lock() + defer r.mu.Unlock() + + if !private { + queue, err := r.reg.Find(ctx, key, mode, create, exclusive) + if err != nil { + return nil, err + } + + if queue != nil { + return queue.(*Queue), nil + } + } + + // Check system-wide limits. + if r.reg.ObjectCount() >= maxQueues { + return nil, linuxerr.ENOSPC + } + + return r.newQueueLocked(ctx, key, fs.FileOwnerFromContext(ctx), fs.FilePermsFromMode(mode)) +} + +// newQueueLocked creates a new queue using the given fields. An error is +// returned if there're no more available identifiers. +// +// Precondition: r.mu must be held. +func (r *Registry) newQueueLocked(ctx context.Context, key ipc.Key, creator fs.FileOwner, perms fs.FilePermissions) (*Queue, error) { + q := &Queue{ + registry: r, + obj: ipc.NewObject(r.reg.UserNS, key, creator, creator, perms), + sendTime: ktime.ZeroTime, + receiveTime: ktime.ZeroTime, + changeTime: ktime.NowFromContext(ctx), + maxBytes: maxQueueBytes, + } + + err := r.reg.Register(q) + if err != nil { + return nil, err + } + return q, nil +} + +// Remove removes the queue with specified ID. All waiters (readers and +// writers) and writers will be awakened and fail. Remove will return an error +// if the ID is invalid, or the the user doesn't have privileges. +func (r *Registry) Remove(id ipc.ID, creds *auth.Credentials) error { + r.mu.Lock() + defer r.mu.Unlock() + + r.reg.Remove(id, creds) + return nil +} + +// Lock implements ipc.Mechanism.Lock. +func (q *Queue) Lock() { + q.mu.Lock() +} + +// Unlock implements ipc.mechanism.Unlock. +// +// +checklocksignore +func (q *Queue) Unlock() { + q.mu.Unlock() +} + +// Object implements ipc.Mechanism.Object. +func (q *Queue) Object() *ipc.Object { + return q.obj +} + +// Destroy implements ipc.Mechanism.Destroy. +func (q *Queue) Destroy() { + q.dead = true + + // Notify waiters. Senders and receivers will try to run, and return an + // error (EIDRM). Waiters should remove themselves from the queue after + // waking up. + q.senders.Notify(waiter.EventOut) + q.receivers.Notify(waiter.EventIn) +} + +// ID returns queue's ID. +func (q *Queue) ID() ipc.ID { + return q.obj.ID +} diff --git a/pkg/sentry/kernel/ptrace.go b/pkg/sentry/kernel/ptrace.go index 21358ec92..079294f81 100644 --- a/pkg/sentry/kernel/ptrace.go +++ b/pkg/sentry/kernel/ptrace.go @@ -768,14 +768,14 @@ const ( // ptraceClone is called at the end of a clone or fork syscall to check if t // should enter PTRACE_EVENT_CLONE, PTRACE_EVENT_FORK, or PTRACE_EVENT_VFORK // stop. child is the new task. -func (t *Task) ptraceClone(kind ptraceCloneKind, child *Task, opts *CloneOptions) bool { +func (t *Task) ptraceClone(kind ptraceCloneKind, child *Task, args *linux.CloneArgs) bool { if !t.hasTracer() { return false } t.tg.pidns.owner.mu.Lock() defer t.tg.pidns.owner.mu.Unlock() event := false - if !opts.Untraced { + if args.Flags&linux.CLONE_UNTRACED == 0 { switch kind { case ptraceCloneKindClone: if t.ptraceOpts.TraceClone { @@ -810,7 +810,7 @@ func (t *Task) ptraceClone(kind ptraceCloneKind, child *Task, opts *CloneOptions // clone(2)'s documentation of CLONE_UNTRACED and CLONE_PTRACE is // confusingly wrong; see kernel/fork.c:_do_fork() => copy_process() => // include/linux/ptrace.h:ptrace_init_task(). - if event || opts.InheritTracer { + if event || args.Flags&linux.CLONE_PTRACE != 0 { tracer := t.Tracer() if tracer != nil { child.ptraceTracer.Store(tracer) diff --git a/pkg/sentry/kernel/semaphore/BUILD b/pkg/sentry/kernel/semaphore/BUILD index a787c00a8..2ae08ed12 100644 --- a/pkg/sentry/kernel/semaphore/BUILD +++ b/pkg/sentry/kernel/semaphore/BUILD @@ -26,9 +26,9 @@ go_library( "//pkg/abi/linux", "//pkg/context", "//pkg/errors/linuxerr", - "//pkg/log", "//pkg/sentry/fs", "//pkg/sentry/kernel/auth", + "//pkg/sentry/kernel/ipc", "//pkg/sentry/kernel/time", "//pkg/sync", "//pkg/syserror", @@ -41,10 +41,11 @@ go_test( srcs = ["semaphore_test.go"], library = ":semaphore", deps = [ - "//pkg/abi/linux", - "//pkg/context", - "//pkg/sentry/contexttest", - "//pkg/sentry/kernel/auth", - "//pkg/syserror", + "//pkg/abi/linux", # keep + "//pkg/context", # keep + "//pkg/sentry/contexttest", # keep + "//pkg/sentry/kernel/auth", # keep + "//pkg/sentry/kernel/ipc", # keep + "//pkg/syserror", # keep ], ) diff --git a/pkg/sentry/kernel/semaphore/semaphore.go b/pkg/sentry/kernel/semaphore/semaphore.go index 485c3a788..8610d3fc1 100644 --- a/pkg/sentry/kernel/semaphore/semaphore.go +++ b/pkg/sentry/kernel/semaphore/semaphore.go @@ -21,9 +21,9 @@ import ( "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/errors/linuxerr" - "gvisor.dev/gvisor/pkg/log" "gvisor.dev/gvisor/pkg/sentry/fs" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/kernel/ipc" ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time" "gvisor.dev/gvisor/pkg/sync" "gvisor.dev/gvisor/pkg/syserror" @@ -47,15 +47,15 @@ const ( // // +stateify savable type Registry struct { - // userNS owning the ipc name this registry belongs to. Immutable. - userNS *auth.UserNamespace // mu protects all fields below. - mu sync.Mutex `state:"nosave"` - semaphores map[int32]*Set - lastIDUsed int32 + mu sync.Mutex `state:"nosave"` + + // reg defines basic fields and operations needed for all SysV registries. + reg *ipc.Registry + // indexes maintains a mapping between a set's index in virtual array and // its identifier. - indexes map[int32]int32 + indexes map[int32]ipc.ID } // Set represents a set of semaphores that can be operated atomically. @@ -65,19 +65,11 @@ type Set struct { // registry owning this sem set. Immutable. registry *Registry - // Id is a handle that identifies the set. - ID int32 - - // key is an user provided key that can be shared between processes. - key int32 + // mu protects all fields below. + mu sync.Mutex `state:"nosave"` - // creator is the user that created the set. Immutable. - creator fs.FileOwner + obj *ipc.Object - // mu protects all fields below. - mu sync.Mutex `state:"nosave"` - owner fs.FileOwner - perms fs.FilePermissions opTime ktime.Time changeTime ktime.Time @@ -115,9 +107,8 @@ type waiter struct { // NewRegistry creates a new semaphore set registry. func NewRegistry(userNS *auth.UserNamespace) *Registry { return &Registry{ - userNS: userNS, - semaphores: make(map[int32]*Set), - indexes: make(map[int32]int32), + reg: ipc.NewRegistry(userNS), + indexes: make(map[int32]ipc.ID), } } @@ -126,7 +117,7 @@ func NewRegistry(userNS *auth.UserNamespace) *Registry { // a new set is always created. If create is false, it fails if a set cannot // be found. If exclusive is true, it fails if a set with the same key already // exists. -func (r *Registry) FindOrCreate(ctx context.Context, key, nsems int32, mode linux.FileMode, private, create, exclusive bool) (*Set, error) { +func (r *Registry) FindOrCreate(ctx context.Context, key ipc.Key, nsems int32, mode linux.FileMode, private, create, exclusive bool) (*Set, error) { if nsems < 0 || nsems > semsMax { return nil, linuxerr.EINVAL } @@ -135,31 +126,19 @@ func (r *Registry) FindOrCreate(ctx context.Context, key, nsems int32, mode linu defer r.mu.Unlock() if !private { - // Look up an existing semaphore. - if set := r.findByKey(key); set != nil { - set.mu.Lock() - defer set.mu.Unlock() - - // Check that caller can access semaphore set. - creds := auth.CredentialsFromContext(ctx) - if !set.checkPerms(creds, fs.PermsFromMode(mode)) { - return nil, linuxerr.EACCES - } + set, err := r.reg.Find(ctx, key, mode, create, exclusive) + if err != nil { + return nil, err + } - // Validate parameters. + // Validate semaphore-specific parameters. + if set != nil { + set := set.(*Set) if nsems > int32(set.Size()) { return nil, linuxerr.EINVAL } - if create && exclusive { - return nil, linuxerr.EEXIST - } return set, nil } - - if !create { - // Semaphore not found and should not be created. - return nil, syserror.ENOENT - } } // Zero is only valid if an existing set is found. @@ -169,9 +148,9 @@ func (r *Registry) FindOrCreate(ctx context.Context, key, nsems int32, mode linu // Apply system limits. // - // Map semaphores and map indexes in a registry are of the same size, - // check map semaphores only here for the system limit. - if len(r.semaphores) >= setsMax { + // Map reg.objects and map indexes in a registry are of the same size, + // check map reg.objects only here for the system limit. + if r.reg.ObjectCount() >= setsMax { return nil, syserror.ENOSPC } if r.totalSems() > int(semsTotalMax-nsems) { @@ -179,9 +158,7 @@ func (r *Registry) FindOrCreate(ctx context.Context, key, nsems int32, mode linu } // Finally create a new set. - owner := fs.FileOwnerFromContext(ctx) - perms := fs.FilePermsFromMode(mode) - return r.newSet(ctx, key, owner, owner, perms, nsems) + return r.newSetLocked(ctx, key, fs.FileOwnerFromContext(ctx), fs.FilePermsFromMode(mode), nsems) } // IPCInfo returns information about system-wide semaphore limits and parameters. @@ -208,7 +185,7 @@ func (r *Registry) SemInfo() *linux.SemInfo { defer r.mu.Unlock() info := r.IPCInfo() - info.SemUsz = uint32(len(r.semaphores)) + info.SemUsz = uint32(r.reg.ObjectCount()) info.SemAem = uint32(r.totalSems()) return info @@ -231,77 +208,59 @@ func (r *Registry) HighestIndex() int32 { return highestIndex } -// RemoveID removes set with give 'id' from the registry and marks the set as +// Remove removes set with give 'id' from the registry and marks the set as // dead. All waiters will be awakened and fail. -func (r *Registry) RemoveID(id int32, creds *auth.Credentials) error { +func (r *Registry) Remove(id ipc.ID, creds *auth.Credentials) error { r.mu.Lock() defer r.mu.Unlock() - set := r.semaphores[id] - if set == nil { - return linuxerr.EINVAL - } index, found := r.findIndexByID(id) if !found { - // Inconsistent state. - panic(fmt.Sprintf("unable to find an index for ID: %d", id)) + return linuxerr.EINVAL } + delete(r.indexes, index) - set.mu.Lock() - defer set.mu.Unlock() + r.reg.Remove(id, creds) - // "The effective user ID of the calling process must match the creator or - // owner of the semaphore set, or the caller must be privileged." - if !set.checkCredentials(creds) && !set.checkCapability(creds) { - return linuxerr.EACCES - } - - delete(r.semaphores, set.ID) - delete(r.indexes, index) - set.destroy() return nil } -func (r *Registry) newSet(ctx context.Context, key int32, owner, creator fs.FileOwner, perms fs.FilePermissions, nsems int32) (*Set, error) { +// newSetLocked creates a new Set using given fields. An error is returned if there +// are no more available identifiers. +// +// Precondition: r.mu must be held. +func (r *Registry) newSetLocked(ctx context.Context, key ipc.Key, creator fs.FileOwner, perms fs.FilePermissions, nsems int32) (*Set, error) { set := &Set{ registry: r, - key: key, - owner: owner, - creator: owner, - perms: perms, + obj: ipc.NewObject(r.reg.UserNS, ipc.Key(key), creator, creator, perms), changeTime: ktime.NowFromContext(ctx), sems: make([]sem, nsems), } - // Find the next available ID. - for id := r.lastIDUsed + 1; id != r.lastIDUsed; id++ { - // Handle wrap around. - if id < 0 { - id = 0 - continue - } - if r.semaphores[id] == nil { - index, found := r.findFirstAvailableIndex() - if !found { - panic("unable to find an available index") - } - r.indexes[index] = id - r.lastIDUsed = id - r.semaphores[id] = set - set.ID = id - return set, nil - } + err := r.reg.Register(set) + if err != nil { + return nil, err } - log.Warningf("Semaphore map is full, they must be leaking") - return nil, syserror.ENOMEM + index, found := r.findFirstAvailableIndex() + if !found { + // See linux, ipc/sem.c:newary(). + return nil, linuxerr.ENOSPC + } + r.indexes[index] = set.obj.ID + + return set, nil } // FindByID looks up a set given an ID. -func (r *Registry) FindByID(id int32) *Set { +func (r *Registry) FindByID(id ipc.ID) *Set { r.mu.Lock() defer r.mu.Unlock() - return r.semaphores[id] + mech := r.reg.FindByID(id) + if mech == nil { + return nil + } + return mech.(*Set) } // FindByIndex looks up a set given an index. @@ -313,19 +272,10 @@ func (r *Registry) FindByIndex(index int32) *Set { if !present { return nil } - return r.semaphores[id] + return r.reg.FindByID(id).(*Set) } -func (r *Registry) findByKey(key int32) *Set { - for _, v := range r.semaphores { - if v.key == key { - return v - } - } - return nil -} - -func (r *Registry) findIndexByID(id int32) (int32, bool) { +func (r *Registry) findIndexByID(id ipc.ID) (int32, bool) { for k, v := range r.indexes { if v == id { return k, true @@ -345,12 +295,36 @@ func (r *Registry) findFirstAvailableIndex() (int32, bool) { func (r *Registry) totalSems() int { totalSems := 0 - for _, v := range r.semaphores { - totalSems += v.Size() - } + r.reg.ForAllObjects( + func(o ipc.Mechanism) { + totalSems += o.(*Set).Size() + }, + ) return totalSems } +// ID returns semaphore's ID. +func (s *Set) ID() ipc.ID { + return s.obj.ID +} + +// Object implements ipc.Mechanism.Object. +func (s *Set) Object() *ipc.Object { + return s.obj +} + +// Lock implements ipc.Mechanism.Lock. +func (s *Set) Lock() { + s.mu.Lock() +} + +// Unlock implements ipc.mechanism.Unlock. +// +// +checklocksignore +func (s *Set) Unlock() { + s.mu.Unlock() +} + func (s *Set) findSem(num int32) *sem { if num < 0 || int(num) >= s.Size() { return nil @@ -370,12 +344,12 @@ func (s *Set) Change(ctx context.Context, creds *auth.Credentials, owner fs.File // "The effective UID of the calling process must match the owner or creator // of the semaphore set, or the caller must be privileged." - if !s.checkCredentials(creds) && !s.checkCapability(creds) { + if !s.obj.CheckOwnership(creds) { return linuxerr.EACCES } - s.owner = owner - s.perms = perms + s.obj.Owner = owner + s.obj.Perms = perms s.changeTime = ktime.NowFromContext(ctx) return nil } @@ -395,18 +369,18 @@ func (s *Set) semStat(creds *auth.Credentials, permMask fs.PermMask) (*linux.Sem s.mu.Lock() defer s.mu.Unlock() - if !s.checkPerms(creds, permMask) { + if !s.obj.CheckPermissions(creds, permMask) { return nil, linuxerr.EACCES } return &linux.SemidDS{ SemPerm: linux.IPCPerm{ - Key: uint32(s.key), - UID: uint32(creds.UserNamespace.MapFromKUID(s.owner.UID)), - GID: uint32(creds.UserNamespace.MapFromKGID(s.owner.GID)), - CUID: uint32(creds.UserNamespace.MapFromKUID(s.creator.UID)), - CGID: uint32(creds.UserNamespace.MapFromKGID(s.creator.GID)), - Mode: uint16(s.perms.LinuxMode()), + Key: uint32(s.obj.Key), + UID: uint32(creds.UserNamespace.MapFromKUID(s.obj.Owner.UID)), + GID: uint32(creds.UserNamespace.MapFromKGID(s.obj.Owner.GID)), + CUID: uint32(creds.UserNamespace.MapFromKUID(s.obj.Creator.UID)), + CGID: uint32(creds.UserNamespace.MapFromKGID(s.obj.Creator.GID)), + Mode: uint16(s.obj.Perms.LinuxMode()), Seq: 0, // IPC sequence not supported. }, SemOTime: s.opTime.TimeT(), @@ -425,7 +399,7 @@ func (s *Set) SetVal(ctx context.Context, num int32, val int16, creds *auth.Cred defer s.mu.Unlock() // "The calling process must have alter permission on the semaphore set." - if !s.checkPerms(creds, fs.PermMask{Write: true}) { + if !s.obj.CheckPermissions(creds, fs.PermMask{Write: true}) { return linuxerr.EACCES } @@ -461,7 +435,7 @@ func (s *Set) SetValAll(ctx context.Context, vals []uint16, creds *auth.Credenti defer s.mu.Unlock() // "The calling process must have alter permission on the semaphore set." - if !s.checkPerms(creds, fs.PermMask{Write: true}) { + if !s.obj.CheckPermissions(creds, fs.PermMask{Write: true}) { return linuxerr.EACCES } @@ -483,7 +457,7 @@ func (s *Set) GetVal(num int32, creds *auth.Credentials) (int16, error) { defer s.mu.Unlock() // "The calling process must have read permission on the semaphore set." - if !s.checkPerms(creds, fs.PermMask{Read: true}) { + if !s.obj.CheckPermissions(creds, fs.PermMask{Read: true}) { return 0, linuxerr.EACCES } @@ -500,7 +474,7 @@ func (s *Set) GetValAll(creds *auth.Credentials) ([]uint16, error) { defer s.mu.Unlock() // "The calling process must have read permission on the semaphore set." - if !s.checkPerms(creds, fs.PermMask{Read: true}) { + if !s.obj.CheckPermissions(creds, fs.PermMask{Read: true}) { return nil, linuxerr.EACCES } @@ -517,7 +491,7 @@ func (s *Set) GetPID(num int32, creds *auth.Credentials) (int32, error) { defer s.mu.Unlock() // "The calling process must have read permission on the semaphore set." - if !s.checkPerms(creds, fs.PermMask{Read: true}) { + if !s.obj.CheckPermissions(creds, fs.PermMask{Read: true}) { return 0, linuxerr.EACCES } @@ -533,7 +507,7 @@ func (s *Set) countWaiters(num int32, creds *auth.Credentials, pred func(w *wait defer s.mu.Unlock() // The calling process must have read permission on the semaphore set. - if !s.checkPerms(creds, fs.PermMask{Read: true}) { + if !s.obj.CheckPermissions(creds, fs.PermMask{Read: true}) { return 0, linuxerr.EACCES } @@ -589,7 +563,7 @@ func (s *Set) ExecuteOps(ctx context.Context, ops []linux.Sembuf, creds *auth.Cr } } - if !s.checkPerms(creds, fs.PermMask{Read: readOnly, Write: !readOnly}) { + if !s.obj.CheckPermissions(creds, fs.PermMask{Read: readOnly, Write: !readOnly}) { return nil, 0, linuxerr.EACCES } @@ -675,38 +649,10 @@ func (s *Set) AbortWait(num int32, ch chan struct{}) { // Waiter may not be found in case it raced with wakeWaiters(). } -func (s *Set) checkCredentials(creds *auth.Credentials) bool { - return s.owner.UID == creds.EffectiveKUID || - s.owner.GID == creds.EffectiveKGID || - s.creator.UID == creds.EffectiveKUID || - s.creator.GID == creds.EffectiveKGID -} - -func (s *Set) checkCapability(creds *auth.Credentials) bool { - return creds.HasCapabilityIn(linux.CAP_IPC_OWNER, s.registry.userNS) && creds.UserNamespace.MapFromKUID(s.owner.UID).Ok() -} - -func (s *Set) checkPerms(creds *auth.Credentials, reqPerms fs.PermMask) bool { - // Are we owner, or in group, or other? - p := s.perms.Other - if s.owner.UID == creds.EffectiveKUID { - p = s.perms.User - } else if creds.InGroup(s.owner.GID) { - p = s.perms.Group - } - - // Are permissions satisfied without capability checks? - if p.SupersetOf(reqPerms) { - return true - } - - return s.checkCapability(creds) -} - -// destroy destroys the set. +// Destroy implements ipc.Mechanism.Destroy. // // Preconditions: Caller must hold 's.mu'. -func (s *Set) destroy() { +func (s *Set) Destroy() { // Notify all waiters. They will fail on the next attempt to execute // operations and return error. s.dead = true diff --git a/pkg/sentry/kernel/semaphore/semaphore_test.go b/pkg/sentry/kernel/semaphore/semaphore_test.go index e47acefdf..2e4ab8121 100644 --- a/pkg/sentry/kernel/semaphore/semaphore_test.go +++ b/pkg/sentry/kernel/semaphore/semaphore_test.go @@ -21,6 +21,7 @@ import ( "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/sentry/contexttest" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/kernel/ipc" "gvisor.dev/gvisor/pkg/syserror" ) @@ -55,7 +56,7 @@ func signalled(ch chan struct{}) bool { func TestBasic(t *testing.T) { ctx := contexttest.Context(t) - set := &Set{ID: 123, sems: make([]sem, 1)} + set := &Set{obj: &ipc.Object{ID: 123}, sems: make([]sem, 1)} ops := []linux.Sembuf{ {SemOp: 1}, } @@ -76,7 +77,7 @@ func TestBasic(t *testing.T) { func TestWaitForZero(t *testing.T) { ctx := contexttest.Context(t) - set := &Set{ID: 123, sems: make([]sem, 1)} + set := &Set{obj: &ipc.Object{ID: 123}, sems: make([]sem, 1)} ops := []linux.Sembuf{ {SemOp: 0}, } @@ -115,7 +116,7 @@ func TestWaitForZero(t *testing.T) { func TestNoWait(t *testing.T) { ctx := contexttest.Context(t) - set := &Set{ID: 123, sems: make([]sem, 1)} + set := &Set{obj: &ipc.Object{ID: 123}, sems: make([]sem, 1)} ops := []linux.Sembuf{ {SemOp: 1}, } @@ -138,11 +139,12 @@ func TestUnregister(t *testing.T) { ctx := contexttest.Context(t) r := NewRegistry(auth.NewRootUserNamespace()) set, err := r.FindOrCreate(ctx, 123, 2, linux.FileMode(0x600), true, true, true) + if err != nil { t.Fatalf("FindOrCreate() failed, err: %v", err) } - if got := r.FindByID(set.ID); got.ID != set.ID { - t.Fatalf("FindById(%d) failed, got: %+v, expected: %+v", set.ID, got, set) + if got := r.FindByID(set.obj.ID); got.obj.ID != set.obj.ID { + t.Fatalf("FindById(%d) failed, got: %+v, expected: %+v", set.obj.ID, got, set) } ops := []linux.Sembuf{ @@ -155,14 +157,14 @@ func TestUnregister(t *testing.T) { } creds := auth.CredentialsFromContext(ctx) - if err := r.RemoveID(set.ID, creds); err != nil { - t.Fatalf("RemoveID(%d) failed, err: %v", set.ID, err) + if err := r.Remove(set.obj.ID, creds); err != nil { + t.Fatalf("Remove(%d) failed, err: %v", set.obj.ID, err) } if !set.dead { t.Fatalf("set is not dead: %+v", set) } - if got := r.FindByID(set.ID); got != nil { - t.Fatalf("FindById(%d) failed, got: %+v, expected: nil", set.ID, got) + if got := r.FindByID(set.obj.ID); got != nil { + t.Fatalf("FindById(%d) failed, got: %+v, expected: nil", set.obj.ID, got) } for i, ch := range chs { if !signalled(ch) { diff --git a/pkg/sentry/kernel/shm/BUILD b/pkg/sentry/kernel/shm/BUILD index 5b69333fe..4e8deac4c 100644 --- a/pkg/sentry/kernel/shm/BUILD +++ b/pkg/sentry/kernel/shm/BUILD @@ -36,6 +36,7 @@ go_library( "//pkg/sentry/device", "//pkg/sentry/fs", "//pkg/sentry/kernel/auth", + "//pkg/sentry/kernel/ipc", "//pkg/sentry/kernel/time", "//pkg/sentry/memmap", "//pkg/sentry/pgalloc", diff --git a/pkg/sentry/kernel/shm/shm.go b/pkg/sentry/kernel/shm/shm.go index f7ac4c2b2..2abf467d7 100644 --- a/pkg/sentry/kernel/shm/shm.go +++ b/pkg/sentry/kernel/shm/shm.go @@ -43,6 +43,7 @@ import ( "gvisor.dev/gvisor/pkg/log" "gvisor.dev/gvisor/pkg/sentry/fs" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/kernel/ipc" ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time" "gvisor.dev/gvisor/pkg/sentry/memmap" "gvisor.dev/gvisor/pkg/sentry/pgalloc" @@ -51,12 +52,6 @@ import ( "gvisor.dev/gvisor/pkg/syserror" ) -// Key represents a shm segment key. Analogous to a file name. -type Key int32 - -// ID represents the opaque handle for a shm segment. Analogous to an fd. -type ID int32 - // Registry tracks all shared memory segments in an IPC namespace. The registry // provides the mechanisms for creating and finding segments, and reporting // global shm parameters. @@ -69,50 +64,51 @@ type Registry struct { // mu protects all fields below. mu sync.Mutex `state:"nosave"` - // shms maps segment ids to segments. + // reg defines basic fields and operations needed for all SysV registries. // - // shms holds all referenced segments, which are removed on the last + // Withing reg, there are two maps, Objects and KeysToIDs. + // + // reg.objects holds all referenced segments, which are removed on the last // DecRef. Thus, it cannot itself hold a reference on the Shm. // // Since removal only occurs after the last (unlocked) DecRef, there // exists a short window during which a Shm still exists in Shm, but is // unreferenced. Users must use TryIncRef to determine if the Shm is // still valid. - shms map[ID]*Shm - - // keysToShms maps segment keys to segments. // - // Shms in keysToShms are guaranteed to be referenced, as they are + // keysToIDs maps segment keys to IDs. + // + // Shms in keysToIDs are guaranteed to be referenced, as they are // removed by disassociateKey before the last DecRef. - keysToShms map[Key]*Shm + reg *ipc.Registry // Sum of the sizes of all existing segments rounded up to page size, in // units of page size. totalPages uint64 - - // ID assigned to the last created segment. Used to quickly find the next - // unused ID. - lastIDUsed ID } // NewRegistry creates a new shm registry. func NewRegistry(userNS *auth.UserNamespace) *Registry { return &Registry{ - userNS: userNS, - shms: make(map[ID]*Shm), - keysToShms: make(map[Key]*Shm), + userNS: userNS, + reg: ipc.NewRegistry(userNS), } } // FindByID looks up a segment given an ID. // // FindByID returns a reference on Shm. -func (r *Registry) FindByID(id ID) *Shm { +func (r *Registry) FindByID(id ipc.ID) *Shm { r.mu.Lock() defer r.mu.Unlock() - s := r.shms[id] + mech := r.reg.FindByID(id) + if mech == nil { + return nil + } + s := mech.(*Shm) + // Take a reference on s. If TryIncRef fails, s has reached the last - // DecRef, but hasn't quite been removed from r.shms yet. + // DecRef, but hasn't quite been removed from r.reg.objects yet. if s != nil && s.TryIncRef() { return s } @@ -129,9 +125,9 @@ func (r *Registry) dissociateKey(s *Shm) { defer r.mu.Unlock() s.mu.Lock() defer s.mu.Unlock() - if s.key != linux.IPC_PRIVATE { - delete(r.keysToShms, s.key) - s.key = linux.IPC_PRIVATE + if s.obj.Key != linux.IPC_PRIVATE { + r.reg.DissociateKey(s.obj.Key) + s.obj.Key = linux.IPC_PRIVATE } } @@ -139,7 +135,7 @@ func (r *Registry) dissociateKey(s *Shm) { // analogous to open(2). // // FindOrCreate returns a reference on Shm. -func (r *Registry) FindOrCreate(ctx context.Context, pid int32, key Key, size uint64, mode linux.FileMode, private, create, exclusive bool) (*Shm, error) { +func (r *Registry) FindOrCreate(ctx context.Context, pid int32, key ipc.Key, size uint64, mode linux.FileMode, private, create, exclusive bool) (*Shm, error) { if (create || private) && (size < linux.SHMMIN || size > linux.SHMMAX) { // "A new segment was to be created and size is less than SHMMIN or // greater than SHMMAX." - man shmget(2) @@ -152,49 +148,29 @@ func (r *Registry) FindOrCreate(ctx context.Context, pid int32, key Key, size ui r.mu.Lock() defer r.mu.Unlock() - if len(r.shms) >= linux.SHMMNI { + if r.reg.ObjectCount() >= linux.SHMMNI { // "All possible shared memory IDs have been taken (SHMMNI) ..." // - man shmget(2) return nil, syserror.ENOSPC } if !private { - // Look up an existing segment. - if shm := r.keysToShms[key]; shm != nil { - shm.mu.Lock() - defer shm.mu.Unlock() - - // Check that caller can access the segment. - if !shm.checkPermissions(ctx, fs.PermsFromMode(mode)) { - // "The user does not have permission to access the shared - // memory segment, and does not have the CAP_IPC_OWNER - // capability in the user namespace that governs its IPC - // namespace." - man shmget(2) - return nil, linuxerr.EACCES - } + shm, err := r.reg.Find(ctx, key, mode, create, exclusive) + if err != nil { + return nil, err + } + // Validate shm-specific parameters. + if shm != nil { + shm := shm.(*Shm) if size > shm.size { // "A segment for the given key exists, but size is greater than // the size of that segment." - man shmget(2) return nil, linuxerr.EINVAL } - - if create && exclusive { - // "IPC_CREAT and IPC_EXCL were specified in shmflg, but a - // shared memory segment already exists for key." - // - man shmget(2) - return nil, linuxerr.EEXIST - } - shm.IncRef() return shm, nil } - - if !create { - // "No segment exists for the given key, and IPC_CREAT was not - // specified." - man shmget(2) - return nil, syserror.ENOENT - } } var sizeAligned uint64 @@ -212,9 +188,7 @@ func (r *Registry) FindOrCreate(ctx context.Context, pid int32, key Key, size ui } // Need to create a new segment. - creator := fs.FileOwnerFromContext(ctx) - perms := fs.FilePermsFromMode(mode) - s, err := r.newShm(ctx, pid, key, creator, perms, size) + s, err := r.newShmLocked(ctx, pid, key, fs.FileOwnerFromContext(ctx), fs.FilePermsFromMode(mode), size) if err != nil { return nil, err } @@ -224,10 +198,10 @@ func (r *Registry) FindOrCreate(ctx context.Context, pid int32, key Key, size ui return s, nil } -// newShm creates a new segment in the registry. +// newShmLocked creates a new segment in the registry. // // Precondition: Caller must hold r.mu. -func (r *Registry) newShm(ctx context.Context, pid int32, key Key, creator fs.FileOwner, perms fs.FilePermissions, size uint64) (*Shm, error) { +func (r *Registry) newShmLocked(ctx context.Context, pid int32, key ipc.Key, creator fs.FileOwner, perms fs.FilePermissions, size uint64) (*Shm, error) { mfp := pgalloc.MemoryFileProviderFromContext(ctx) if mfp == nil { panic(fmt.Sprintf("context.Context %T lacks non-nil value for key %T", ctx, pgalloc.CtxMemoryFileProvider)) @@ -242,40 +216,21 @@ func (r *Registry) newShm(ctx context.Context, pid int32, key Key, creator fs.Fi shm := &Shm{ mfp: mfp, registry: r, - creator: creator, size: size, effectiveSize: effectiveSize, + obj: ipc.NewObject(r.reg.UserNS, ipc.Key(key), creator, creator, perms), fr: fr, - key: key, - perms: perms, - owner: creator, creatorPID: pid, changeTime: ktime.NowFromContext(ctx), } shm.InitRefs() - // Find the next available ID. - for id := r.lastIDUsed + 1; id != r.lastIDUsed; id++ { - // Handle wrap around. - if id < 0 { - id = 0 - continue - } - if r.shms[id] == nil { - r.lastIDUsed = id - - shm.ID = id - r.shms[id] = shm - r.keysToShms[key] = shm - - r.totalPages += effectiveSize / hostarch.PageSize - - return shm, nil - } + if err := r.reg.Register(shm); err != nil { + return nil, err } + r.totalPages += effectiveSize / hostarch.PageSize - log.Warningf("Shm ids exhuasted, they may be leaking") - return nil, syserror.ENOSPC + return shm, nil } // IPCInfo reports global parameters for sysv shared memory segments on this @@ -297,7 +252,7 @@ func (r *Registry) ShmInfo() *linux.ShmInfo { defer r.mu.Unlock() return &linux.ShmInfo{ - UsedIDs: int32(r.lastIDUsed), + UsedIDs: int32(r.reg.LastIDUsed()), ShmTot: r.totalPages, ShmRss: r.totalPages, // We could probably get a better estimate from memory accounting. ShmSwp: 0, // No reclaim at the moment. @@ -314,11 +269,11 @@ func (r *Registry) remove(s *Shm) { s.mu.Lock() defer s.mu.Unlock() - if s.key != linux.IPC_PRIVATE { + if s.obj.Key != linux.IPC_PRIVATE { panic(fmt.Sprintf("Attempted to remove %s from the registry whose key is still associated", s.debugLocked())) } - delete(r.shms, s.ID) + r.reg.DissociateID(s.obj.ID) r.totalPages -= s.effectiveSize / hostarch.PageSize } @@ -330,13 +285,16 @@ func (r *Registry) Release(ctx context.Context) { // the IPC namespace containing it has no more references. toRelease := make([]*Shm, 0) r.mu.Lock() - for _, s := range r.keysToShms { - s.mu.Lock() - if !s.pendingDestruction { - toRelease = append(toRelease, s) - } - s.mu.Unlock() - } + r.reg.ForAllObjects( + func(o ipc.Mechanism) { + s := o.(*Shm) + s.mu.Lock() + if !s.pendingDestruction { + toRelease = append(toRelease, s) + } + s.mu.Unlock() + }, + ) r.mu.Unlock() for _, s := range toRelease { @@ -374,12 +332,6 @@ type Shm struct { // registry points to the shm registry containing this segment. Immutable. registry *Registry - // ID is the kernel identifier for this segment. Immutable. - ID ID - - // creator is the user that created the segment. Immutable. - creator fs.FileOwner - // size is the requested size of the segment at creation, in // bytes. Immutable. size uint64 @@ -397,14 +349,8 @@ type Shm struct { // mu protects all fields below. mu sync.Mutex `state:"nosave"` - // key is the public identifier for this segment. - key Key - - // perms is the access permissions for the segment. - perms fs.FilePermissions + obj *ipc.Object - // owner of this segment. - owner fs.FileOwner // attachTime is updated on every successful shmat. attachTime ktime.Time // detachTime is updated on every successful shmdt. @@ -426,17 +372,44 @@ type Shm struct { pendingDestruction bool } +// ID returns object's ID. +func (s *Shm) ID() ipc.ID { + return s.obj.ID +} + +// Object implements ipc.Mechanism.Object. +func (s *Shm) Object() *ipc.Object { + return s.obj +} + +// Destroy implements ipc.Mechanism.Destroy. No work is performed on shm.Destroy +// because a different removal mechanism is used in shm. See Shm.MarkDestroyed. +func (s *Shm) Destroy() { +} + +// Lock implements ipc.Mechanism.Lock. +func (s *Shm) Lock() { + s.mu.Lock() +} + +// Unlock implements ipc.mechanism.Unlock. +// +// +checklocksignore +func (s *Shm) Unlock() { + s.mu.Unlock() +} + // Precondition: Caller must hold s.mu. func (s *Shm) debugLocked() string { return fmt.Sprintf("Shm{id: %d, key: %d, size: %d bytes, refs: %d, destroyed: %v}", - s.ID, s.key, s.size, s.ReadRefs(), s.pendingDestruction) + s.obj.ID, s.obj.Key, s.size, s.ReadRefs(), s.pendingDestruction) } // MappedName implements memmap.MappingIdentity.MappedName. func (s *Shm) MappedName(ctx context.Context) string { s.mu.Lock() defer s.mu.Unlock() - return fmt.Sprintf("SYSV%08d", s.key) + return fmt.Sprintf("SYSV%08d", s.obj.Key) } // DeviceID implements memmap.MappingIdentity.DeviceID. @@ -448,7 +421,7 @@ func (s *Shm) DeviceID() uint64 { func (s *Shm) InodeID() uint64 { // "shmid gets reported as "inode#" in /proc/pid/maps. proc-ps tools use // this. Changing this will break them." -- Linux, ipc/shm.c:newseg() - return uint64(s.ID) + return uint64(s.obj.ID) } // DecRef drops a reference on s. @@ -551,7 +524,8 @@ func (s *Shm) ConfigureAttach(ctx context.Context, addr hostarch.Addr, opts Atta return memmap.MMapOpts{}, syserror.EIDRM } - if !s.checkPermissions(ctx, fs.PermMask{ + creds := auth.CredentialsFromContext(ctx) + if !s.obj.CheckPermissions(creds, fs.PermMask{ Read: true, Write: !opts.Readonly, Execute: opts.Execute, @@ -591,7 +565,8 @@ func (s *Shm) IPCStat(ctx context.Context) (*linux.ShmidDS, error) { // "The caller must have read permission on the shared memory segment." // - man shmctl(2) - if !s.checkPermissions(ctx, fs.PermMask{Read: true}) { + creds := auth.CredentialsFromContext(ctx) + if !s.obj.CheckPermissions(creds, fs.PermMask{Read: true}) { // "IPC_STAT or SHM_STAT is requested and shm_perm.mode does not allow // read access for shmid, and the calling process does not have the // CAP_IPC_OWNER capability in the user namespace that governs its IPC @@ -603,7 +578,6 @@ func (s *Shm) IPCStat(ctx context.Context) (*linux.ShmidDS, error) { if s.pendingDestruction { mode |= linux.SHM_DEST } - creds := auth.CredentialsFromContext(ctx) // Use the reference count as a rudimentary count of the number of // attaches. We exclude: @@ -620,12 +594,12 @@ func (s *Shm) IPCStat(ctx context.Context) (*linux.ShmidDS, error) { ds := &linux.ShmidDS{ ShmPerm: linux.IPCPerm{ - Key: uint32(s.key), - UID: uint32(creds.UserNamespace.MapFromKUID(s.owner.UID)), - GID: uint32(creds.UserNamespace.MapFromKGID(s.owner.GID)), - CUID: uint32(creds.UserNamespace.MapFromKUID(s.creator.UID)), - CGID: uint32(creds.UserNamespace.MapFromKGID(s.creator.GID)), - Mode: mode | uint16(s.perms.LinuxMode()), + Key: uint32(s.obj.Key), + UID: uint32(creds.UserNamespace.MapFromKUID(s.obj.Owner.UID)), + GID: uint32(creds.UserNamespace.MapFromKGID(s.obj.Owner.GID)), + CUID: uint32(creds.UserNamespace.MapFromKUID(s.obj.Creator.UID)), + CGID: uint32(creds.UserNamespace.MapFromKGID(s.obj.Creator.GID)), + Mode: mode | uint16(s.obj.Perms.LinuxMode()), Seq: 0, // IPC sequences not supported. }, ShmSegsz: s.size, @@ -645,11 +619,11 @@ func (s *Shm) Set(ctx context.Context, ds *linux.ShmidDS) error { s.mu.Lock() defer s.mu.Unlock() - if !s.checkOwnership(ctx) { + creds := auth.CredentialsFromContext(ctx) + if !s.obj.CheckOwnership(creds) { return linuxerr.EPERM } - creds := auth.CredentialsFromContext(ctx) uid := creds.UserNamespace.MapToKUID(auth.UID(ds.ShmPerm.UID)) gid := creds.UserNamespace.MapToKGID(auth.GID(ds.ShmPerm.GID)) if !uid.Ok() || !gid.Ok() { @@ -659,10 +633,10 @@ func (s *Shm) Set(ctx context.Context, ds *linux.ShmidDS) error { // User may only modify the lower 9 bits of the mode. All the other bits are // always 0 for the underlying inode. mode := linux.FileMode(ds.ShmPerm.Mode & 0x1ff) - s.perms = fs.FilePermsFromMode(mode) + s.obj.Perms = fs.FilePermsFromMode(mode) - s.owner.UID = uid - s.owner.GID = gid + s.obj.Owner.UID = uid + s.obj.Owner.GID = gid s.changeTime = ktime.NowFromContext(ctx) return nil @@ -691,40 +665,3 @@ func (s *Shm) MarkDestroyed(ctx context.Context) { s.DecRef(ctx) return } - -// checkOwnership verifies whether a segment may be accessed by ctx as an -// owner. See ipc/util.c:ipcctl_pre_down_nolock() in Linux. -// -// Precondition: Caller must hold s.mu. -func (s *Shm) checkOwnership(ctx context.Context) bool { - creds := auth.CredentialsFromContext(ctx) - if s.owner.UID == creds.EffectiveKUID || s.creator.UID == creds.EffectiveKUID { - return true - } - - // Tasks with CAP_SYS_ADMIN may bypass ownership checks. Strangely, Linux - // doesn't use CAP_IPC_OWNER for this despite CAP_IPC_OWNER being documented - // for use to "override IPC ownership checks". - return creds.HasCapabilityIn(linux.CAP_SYS_ADMIN, s.registry.userNS) -} - -// checkPermissions verifies whether a segment is accessible by ctx for access -// described by req. See ipc/util.c:ipcperms() in Linux. -// -// Precondition: Caller must hold s.mu. -func (s *Shm) checkPermissions(ctx context.Context, req fs.PermMask) bool { - creds := auth.CredentialsFromContext(ctx) - - p := s.perms.Other - if s.owner.UID == creds.EffectiveKUID { - p = s.perms.User - } else if creds.InGroup(s.owner.GID) { - p = s.perms.Group - } - if p.SupersetOf(req) { - return true - } - - // Tasks with CAP_IPC_OWNER may bypass permission checks. - return creds.HasCapabilityIn(linux.CAP_IPC_OWNER, s.registry.userNS) -} diff --git a/pkg/sentry/kernel/task_clone.go b/pkg/sentry/kernel/task_clone.go index 7e1347aa6..da4b77ca2 100644 --- a/pkg/sentry/kernel/task_clone.go +++ b/pkg/sentry/kernel/task_clone.go @@ -26,140 +26,39 @@ import ( "gvisor.dev/gvisor/pkg/usermem" ) -// SharingOptions controls what resources are shared by a new task created by -// Task.Clone, or an existing task affected by Task.Unshare. -type SharingOptions struct { - // If NewAddressSpace is true, the task should have an independent virtual - // address space. - NewAddressSpace bool - - // If NewSignalHandlers is true, the task should use an independent set of - // signal handlers. - NewSignalHandlers bool - - // If NewThreadGroup is true, the task should be the leader of its own - // thread group. TerminationSignal is the signal that the thread group - // will send to its parent when it exits. If NewThreadGroup is false, - // TerminationSignal is ignored. - NewThreadGroup bool - TerminationSignal linux.Signal - - // If NewPIDNamespace is true: - // - // - In the context of Task.Clone, the new task should be the init task - // (TID 1) in a new PID namespace. - // - // - In the context of Task.Unshare, the task should create a new PID - // namespace, and all subsequent clones of the task should be members of - // the new PID namespace. - NewPIDNamespace bool - - // If NewUserNamespace is true, the task should have an independent user - // namespace. - NewUserNamespace bool - - // If NewNetworkNamespace is true, the task should have an independent - // network namespace. - NewNetworkNamespace bool - - // If NewFiles is true, the task should use an independent file descriptor - // table. - NewFiles bool - - // If NewFSContext is true, the task should have an independent FSContext. - NewFSContext bool - - // If NewUTSNamespace is true, the task should have an independent UTS - // namespace. - NewUTSNamespace bool - - // If NewIPCNamespace is true, the task should have an independent IPC - // namespace. - NewIPCNamespace bool -} - -// CloneOptions controls the behavior of Task.Clone. -type CloneOptions struct { - // SharingOptions defines the set of resources that the new task will share - // with its parent. - SharingOptions - - // Stack is the initial stack pointer of the new task. If Stack is 0, the - // new task will start with the same stack pointer as its parent. - Stack hostarch.Addr - - // If SetTLS is true, set the new task's TLS (thread-local storage) - // descriptor to TLS. If SetTLS is false, TLS is ignored. - SetTLS bool - TLS hostarch.Addr - - // If ChildClearTID is true, when the child exits, 0 is written to the - // address ChildTID in the child's memory, and if the write is successful a - // futex wake on the same address is performed. - // - // If ChildSetTID is true, the child's thread ID (in the child's PID - // namespace) is written to address ChildTID in the child's memory. (As in - // Linux, failed writes are silently ignored.) - ChildClearTID bool - ChildSetTID bool - ChildTID hostarch.Addr - - // If ParentSetTID is true, the child's thread ID (in the parent's PID - // namespace) is written to address ParentTID in the parent's memory. (As - // in Linux, failed writes are silently ignored.) - // - // Older versions of the clone(2) man page state that CLONE_PARENT_SETTID - // causes the child's thread ID to be written to ptid in both the parent - // and child's memory, but this is a documentation error fixed by - // 87ab04792ced ("clone.2: Fix description of CLONE_PARENT_SETTID"). - ParentSetTID bool - ParentTID hostarch.Addr - - // If Vfork is true, place the parent in vforkStop until the cloned task - // releases its TaskImage. - Vfork bool - - // If Untraced is true, do not report PTRACE_EVENT_CLONE/FORK/VFORK for - // this clone(), and do not ptrace-attach the caller's tracer to the new - // task. (PTRACE_EVENT_VFORK_DONE will still be reported if appropriate). - Untraced bool - - // If InheritTracer is true, ptrace-attach the caller's tracer to the new - // task, even if no PTRACE_EVENT_CLONE/FORK/VFORK event would be reported - // for it. If both Untraced and InheritTracer are true, no event will be - // reported, but tracer inheritance will still occur. - InheritTracer bool -} - // Clone implements the clone(2) syscall and returns the thread ID of the new // task in t's PID namespace. Clone may return both a non-zero thread ID and a // non-nil error. // // Preconditions: The caller must be running Task.doSyscallInvoke on the task // goroutine. -func (t *Task) Clone(opts *CloneOptions) (ThreadID, *SyscallControl, error) { +func (t *Task) Clone(args *linux.CloneArgs) (ThreadID, *SyscallControl, error) { // Since signal actions may refer to application signal handlers by virtual // address, any set of signal handlers must refer to the same address // space. - if !opts.NewSignalHandlers && opts.NewAddressSpace { + if args.Flags&(linux.CLONE_SIGHAND|linux.CLONE_VM) == linux.CLONE_SIGHAND { return 0, nil, linuxerr.EINVAL } // In order for the behavior of thread-group-directed signals to be sane, // all tasks in a thread group must share signal handlers. - if !opts.NewThreadGroup && opts.NewSignalHandlers { + if args.Flags&(linux.CLONE_THREAD|linux.CLONE_SIGHAND) == linux.CLONE_THREAD { return 0, nil, linuxerr.EINVAL } // All tasks in a thread group must be in the same PID namespace. - if !opts.NewThreadGroup && (opts.NewPIDNamespace || t.childPIDNamespace != nil) { + if (args.Flags&linux.CLONE_THREAD != 0) && (args.Flags&linux.CLONE_NEWPID != 0 || t.childPIDNamespace != nil) { return 0, nil, linuxerr.EINVAL } // The two different ways of specifying a new PID namespace are // incompatible. - if opts.NewPIDNamespace && t.childPIDNamespace != nil { + if args.Flags&linux.CLONE_NEWPID != 0 && t.childPIDNamespace != nil { return 0, nil, linuxerr.EINVAL } // Thread groups and FS contexts cannot span user namespaces. - if opts.NewUserNamespace && (!opts.NewThreadGroup || !opts.NewFSContext) { + if args.Flags&linux.CLONE_NEWUSER != 0 && args.Flags&(linux.CLONE_THREAD|linux.CLONE_FS) != 0 { + return 0, nil, linuxerr.EINVAL + } + // args.ExitSignal must be a valid signal. + if args.ExitSignal != 0 && !linux.Signal(args.ExitSignal).IsValid() { return 0, nil, linuxerr.EINVAL } @@ -174,7 +73,7 @@ func (t *Task) Clone(opts *CloneOptions) (ThreadID, *SyscallControl, error) { // user_namespaces(7) creds := t.Credentials() userns := creds.UserNamespace - if opts.NewUserNamespace { + if args.Flags&linux.CLONE_NEWUSER != 0 { var err error // "EPERM (since Linux 3.9): CLONE_NEWUSER was specified in flags and // the caller is in a chroot environment (i.e., the caller's root @@ -189,21 +88,19 @@ func (t *Task) Clone(opts *CloneOptions) (ThreadID, *SyscallControl, error) { return 0, nil, err } } - if (opts.NewPIDNamespace || opts.NewNetworkNamespace || opts.NewUTSNamespace) && !creds.HasCapabilityIn(linux.CAP_SYS_ADMIN, userns) { + if args.Flags&(linux.CLONE_NEWPID|linux.CLONE_NEWNET|linux.CLONE_NEWUTS|linux.CLONE_NEWIPC) != 0 && !creds.HasCapabilityIn(linux.CAP_SYS_ADMIN, userns) { return 0, nil, linuxerr.EPERM } utsns := t.UTSNamespace() - if opts.NewUTSNamespace { + if args.Flags&linux.CLONE_NEWUTS != 0 { // Note that this must happen after NewUserNamespace so we get // the new userns if there is one. utsns = t.UTSNamespace().Clone(userns) } ipcns := t.IPCNamespace() - if opts.NewIPCNamespace { - // Note that "If CLONE_NEWIPC is set, then create the process in a new IPC - // namespace" + if args.Flags&linux.CLONE_NEWIPC != 0 { ipcns = NewIPCNamespace(userns) } else { ipcns.IncRef() @@ -214,7 +111,7 @@ func (t *Task) Clone(opts *CloneOptions) (ThreadID, *SyscallControl, error) { defer cu.Clean() netns := t.NetworkNamespace() - if opts.NewNetworkNamespace { + if args.Flags&linux.CLONE_NEWNET != 0 { netns = inet.NewNamespace(netns) } @@ -227,7 +124,7 @@ func (t *Task) Clone(opts *CloneOptions) (ThreadID, *SyscallControl, error) { }) } - image, err := t.image.Fork(t, t.k, !opts.NewAddressSpace) + image, err := t.image.Fork(t, t.k, args.Flags&linux.CLONE_VM != 0) if err != nil { return 0, nil, err } @@ -236,17 +133,17 @@ func (t *Task) Clone(opts *CloneOptions) (ThreadID, *SyscallControl, error) { }) // clone() returns 0 in the child. image.Arch.SetReturn(0) - if opts.Stack != 0 { - image.Arch.SetStack(uintptr(opts.Stack)) + if args.Stack != 0 { + image.Arch.SetStack(uintptr(args.Stack)) } - if opts.SetTLS { - if !image.Arch.SetTLS(uintptr(opts.TLS)) { + if args.Flags&linux.CLONE_SETTLS != 0 { + if !image.Arch.SetTLS(uintptr(args.TLS)) { return 0, nil, linuxerr.EPERM } } var fsContext *FSContext - if opts.NewFSContext { + if args.Flags&linux.CLONE_FS == 0 { fsContext = t.fsContext.Fork() } else { fsContext = t.fsContext @@ -254,7 +151,7 @@ func (t *Task) Clone(opts *CloneOptions) (ThreadID, *SyscallControl, error) { } var fdTable *FDTable - if opts.NewFiles { + if args.Flags&linux.CLONE_FILES == 0 { fdTable = t.fdTable.Fork(t) } else { fdTable = t.fdTable @@ -264,22 +161,22 @@ func (t *Task) Clone(opts *CloneOptions) (ThreadID, *SyscallControl, error) { pidns := t.tg.pidns if t.childPIDNamespace != nil { pidns = t.childPIDNamespace - } else if opts.NewPIDNamespace { + } else if args.Flags&linux.CLONE_NEWPID != 0 { pidns = pidns.NewChild(userns) } tg := t.tg rseqAddr := hostarch.Addr(0) rseqSignature := uint32(0) - if opts.NewThreadGroup { + if args.Flags&linux.CLONE_THREAD == 0 { if tg.mounts != nil { tg.mounts.IncRef() } sh := t.tg.signalHandlers - if opts.NewSignalHandlers { + if args.Flags&linux.CLONE_SIGHAND == 0 { sh = sh.Fork() } - tg = t.k.NewThreadGroup(tg.mounts, pidns, sh, opts.TerminationSignal, tg.limits.GetCopy()) + tg = t.k.NewThreadGroup(tg.mounts, pidns, sh, linux.Signal(args.ExitSignal), tg.limits.GetCopy()) tg.oomScoreAdj = atomic.LoadInt32(&t.tg.oomScoreAdj) rseqAddr = t.rseqAddr rseqSignature = t.rseqSignature @@ -304,7 +201,7 @@ func (t *Task) Clone(opts *CloneOptions) (ThreadID, *SyscallControl, error) { RSeqSignature: rseqSignature, ContainerID: t.ContainerID(), } - if opts.NewThreadGroup { + if args.Flags&linux.CLONE_THREAD == 0 { cfg.Parent = t } else { cfg.InheritParent = t @@ -322,7 +219,7 @@ func (t *Task) Clone(opts *CloneOptions) (ThreadID, *SyscallControl, error) { // // However kernel/fork.c:copy_process() adds a limitation to this: // "sigaltstack should be cleared when sharing the same VM". - if opts.NewAddressSpace || opts.Vfork { + if args.Flags&linux.CLONE_VM == 0 || args.Flags&linux.CLONE_VFORK != 0 { nt.SetSignalStack(t.SignalStack()) } @@ -347,35 +244,35 @@ func (t *Task) Clone(opts *CloneOptions) (ThreadID, *SyscallControl, error) { copiedFilters := append([]bpf.Program(nil), f.([]bpf.Program)...) nt.syscallFilters.Store(copiedFilters) } - if opts.Vfork { + if args.Flags&linux.CLONE_VFORK != 0 { nt.vforkParent = t } - if opts.ChildClearTID { - nt.SetClearTID(opts.ChildTID) + if args.Flags&linux.CLONE_CHILD_CLEARTID != 0 { + nt.SetClearTID(hostarch.Addr(args.ChildTID)) } - if opts.ChildSetTID { + if args.Flags&linux.CLONE_CHILD_SETTID != 0 { ctid := nt.ThreadID() - ctid.CopyOut(nt.CopyContext(t, usermem.IOOpts{AddressSpaceActive: false}), opts.ChildTID) + ctid.CopyOut(nt.CopyContext(t, usermem.IOOpts{AddressSpaceActive: false}), hostarch.Addr(args.ChildTID)) } ntid := t.tg.pidns.IDOfTask(nt) - if opts.ParentSetTID { - ntid.CopyOut(t, opts.ParentTID) + if args.Flags&linux.CLONE_PARENT_SETTID != 0 { + ntid.CopyOut(t, hostarch.Addr(args.ParentTID)) } kind := ptraceCloneKindClone - if opts.Vfork { + if args.Flags&linux.CLONE_VFORK != 0 { kind = ptraceCloneKindVfork - } else if opts.TerminationSignal == linux.SIGCHLD { + } else if linux.Signal(args.ExitSignal) == linux.SIGCHLD { kind = ptraceCloneKindFork } - if t.ptraceClone(kind, nt, opts) { - if opts.Vfork { + if t.ptraceClone(kind, nt, args) { + if args.Flags&linux.CLONE_VFORK != 0 { return ntid, &SyscallControl{next: &runSyscallAfterPtraceEventClone{vforkChild: nt, vforkChildTID: ntid}}, nil } return ntid, &SyscallControl{next: &runSyscallAfterPtraceEventClone{}}, nil } - if opts.Vfork { + if args.Flags&linux.CLONE_VFORK != 0 { t.maybeBeginVforkStop(nt) return ntid, &SyscallControl{next: &runSyscallAfterVforkStop{childTID: ntid}}, nil } @@ -446,27 +343,35 @@ func (r *runSyscallAfterVforkStop) execute(t *Task) taskRunState { } // Unshare changes the set of resources t shares with other tasks, as specified -// by opts. +// by flags. // // Preconditions: The caller must be running on the task goroutine. -func (t *Task) Unshare(opts *SharingOptions) error { - // In Linux unshare(2), NewThreadGroup implies NewSignalHandlers and - // NewSignalHandlers implies NewAddressSpace. All three flags are no-ops if - // t is the only task using its MM, which due to clone(2)'s rules imply - // that it is also the only task using its signal handlers / in its thread - // group, and cause EINVAL to be returned otherwise. +func (t *Task) Unshare(flags int32) error { + // "CLONE_THREAD, CLONE_SIGHAND, and CLONE_VM can be specified in flags if + // the caller is single threaded (i.e., it is not sharing its address space + // with another process or thread). In this case, these flags have no + // effect. (Note also that specifying CLONE_THREAD automatically implies + // CLONE_VM, and specifying CLONE_VM automatically implies CLONE_SIGHAND.) + // If the process is multithreaded, then the use of these flags results in + // an error." - unshare(2). This is incorrect (cf. + // kernel/fork.c:ksys_unshare()): + // + // - CLONE_THREAD does not imply CLONE_VM. + // + // - CLONE_SIGHAND implies CLONE_THREAD. + // + // - Only CLONE_VM requires that the caller is not sharing its address + // space with another thread. CLONE_SIGHAND requires that the caller is not + // sharing its signal handlers, and CLONE_THREAD requires that the caller + // is the only thread in its thread group. // // Since we don't count the number of tasks using each address space or set - // of signal handlers, we reject NewSignalHandlers and NewAddressSpace - // altogether, and interpret NewThreadGroup as requiring that t be the only - // member of its thread group. This seems to be logically coherent, in the - // sense that clone(2) allows a task to share signal handlers and address - // spaces with tasks in other thread groups. - if opts.NewAddressSpace || opts.NewSignalHandlers { + // of signal handlers, we reject CLONE_VM and CLONE_SIGHAND altogether. + if flags&(linux.CLONE_VM|linux.CLONE_SIGHAND) != 0 { return linuxerr.EINVAL } creds := t.Credentials() - if opts.NewThreadGroup { + if flags&linux.CLONE_THREAD != 0 { t.tg.signalHandlers.mu.Lock() if t.tg.tasksCount != 1 { t.tg.signalHandlers.mu.Unlock() @@ -476,7 +381,7 @@ func (t *Task) Unshare(opts *SharingOptions) error { // This isn't racy because we're the only living task, and therefore // the only task capable of creating new ones, in our thread group. } - if opts.NewUserNamespace { + if flags&linux.CLONE_NEWUSER != 0 { if t.IsChrooted() { return linuxerr.EPERM } @@ -492,7 +397,7 @@ func (t *Task) Unshare(opts *SharingOptions) error { creds = t.Credentials() } haveCapSysAdmin := t.HasCapability(linux.CAP_SYS_ADMIN) - if opts.NewPIDNamespace { + if flags&linux.CLONE_NEWPID != 0 { if !haveCapSysAdmin { return linuxerr.EPERM } @@ -500,14 +405,14 @@ func (t *Task) Unshare(opts *SharingOptions) error { } t.mu.Lock() // Can't defer unlock: DecRefs must occur without holding t.mu. - if opts.NewNetworkNamespace { + if flags&linux.CLONE_NEWNET != 0 { if !haveCapSysAdmin { t.mu.Unlock() return linuxerr.EPERM } t.netns = inet.NewNamespace(t.netns) } - if opts.NewUTSNamespace { + if flags&linux.CLONE_NEWUTS != 0 { if !haveCapSysAdmin { t.mu.Unlock() return linuxerr.EPERM @@ -516,7 +421,7 @@ func (t *Task) Unshare(opts *SharingOptions) error { // new user namespace is used if there is one. t.utsns = t.utsns.Clone(creds.UserNamespace) } - if opts.NewIPCNamespace { + if flags&linux.CLONE_NEWIPC != 0 { if !haveCapSysAdmin { t.mu.Unlock() return linuxerr.EPERM @@ -527,12 +432,12 @@ func (t *Task) Unshare(opts *SharingOptions) error { t.ipcns = NewIPCNamespace(creds.UserNamespace) } var oldFDTable *FDTable - if opts.NewFiles { + if flags&linux.CLONE_FILES != 0 { oldFDTable = t.fdTable t.fdTable = oldFDTable.Fork(t) } var oldFSContext *FSContext - if opts.NewFSContext { + if flags&linux.CLONE_FS != 0 { oldFSContext = t.fsContext t.fsContext = oldFSContext.Fork() } |