diff options
Diffstat (limited to 'pkg/sentry/kernel/fasync')
| -rw-r--r-- | pkg/sentry/kernel/fasync/BUILD | 18 | ||||
| -rw-r--r-- | pkg/sentry/kernel/fasync/fasync.go | 188 |
2 files changed, 206 insertions, 0 deletions
diff --git a/pkg/sentry/kernel/fasync/BUILD b/pkg/sentry/kernel/fasync/BUILD new file mode 100644 index 000000000..2b3955598 --- /dev/null +++ b/pkg/sentry/kernel/fasync/BUILD @@ -0,0 +1,18 @@ +load("//tools:defs.bzl", "go_library") + +package(licenses = ["notice"]) + +go_library( + name = "fasync", + srcs = ["fasync.go"], + visibility = ["//:sandbox"], + deps = [ + "//pkg/abi/linux", + "//pkg/sentry/fs", + "//pkg/sentry/kernel", + "//pkg/sentry/kernel/auth", + "//pkg/sentry/vfs", + "//pkg/sync", + "//pkg/waiter", + ], +) diff --git a/pkg/sentry/kernel/fasync/fasync.go b/pkg/sentry/kernel/fasync/fasync.go new file mode 100644 index 000000000..153d2cd9b --- /dev/null +++ b/pkg/sentry/kernel/fasync/fasync.go @@ -0,0 +1,188 @@ +// Copyright 2018 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 fasync provides FIOASYNC related functionality. +package fasync + +import ( + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/sentry/fs" + "gvisor.dev/gvisor/pkg/sentry/kernel" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/sync" + "gvisor.dev/gvisor/pkg/waiter" +) + +// New creates a new fs.FileAsync. +func New() fs.FileAsync { + return &FileAsync{} +} + +// NewVFS2 creates a new vfs.FileAsync. +func NewVFS2() vfs.FileAsync { + return &FileAsync{} +} + +// FileAsync sends signals when the registered file is ready for IO. +// +// +stateify savable +type FileAsync struct { + // e is immutable after first use (which is protected by mu below). + e waiter.Entry + + // regMu protects registeration and unregistration actions on e. + // + // regMu must be held while registration decisions are being made + // through the registration action itself. + // + // Lock ordering: regMu, mu. + regMu sync.Mutex `state:"nosave"` + + // mu protects all following fields. + // + // Lock ordering: e.mu, mu. + mu sync.Mutex `state:"nosave"` + requester *auth.Credentials + registered bool + + // Only one of the following is allowed to be non-nil. + recipientPG *kernel.ProcessGroup + recipientTG *kernel.ThreadGroup + recipientT *kernel.Task +} + +// Callback sends a signal. +func (a *FileAsync) Callback(e *waiter.Entry) { + a.mu.Lock() + if !a.registered { + a.mu.Unlock() + return + } + t := a.recipientT + tg := a.recipientTG + if a.recipientPG != nil { + tg = a.recipientPG.Originator() + } + if tg != nil { + t = tg.Leader() + } + if t == nil { + // No recipient has been registered. + a.mu.Unlock() + return + } + c := t.Credentials() + // Logic from sigio_perm in fs/fcntl.c. + if a.requester.EffectiveKUID == 0 || + a.requester.EffectiveKUID == c.SavedKUID || + a.requester.EffectiveKUID == c.RealKUID || + a.requester.RealKUID == c.SavedKUID || + a.requester.RealKUID == c.RealKUID { + t.SendSignal(kernel.SignalInfoPriv(linux.SIGIO)) + } + a.mu.Unlock() +} + +// Register sets the file which will be monitored for IO events. +// +// The file must not be currently registered. +func (a *FileAsync) Register(w waiter.Waitable) { + a.regMu.Lock() + defer a.regMu.Unlock() + a.mu.Lock() + + if a.registered { + a.mu.Unlock() + panic("registering already registered file") + } + + if a.e.Callback == nil { + a.e.Callback = a + } + a.registered = true + + a.mu.Unlock() + w.EventRegister(&a.e, waiter.EventIn|waiter.EventOut|waiter.EventErr|waiter.EventHUp) +} + +// Unregister stops monitoring a file. +// +// The file must be currently registered. +func (a *FileAsync) Unregister(w waiter.Waitable) { + a.regMu.Lock() + defer a.regMu.Unlock() + a.mu.Lock() + + if !a.registered { + a.mu.Unlock() + panic("unregistering unregistered file") + } + + a.registered = false + + a.mu.Unlock() + w.EventUnregister(&a.e) +} + +// Owner returns who is currently getting signals. All return values will be +// nil if no one is set to receive signals. +func (a *FileAsync) Owner() (*kernel.Task, *kernel.ThreadGroup, *kernel.ProcessGroup) { + a.mu.Lock() + defer a.mu.Unlock() + return a.recipientT, a.recipientTG, a.recipientPG +} + +// SetOwnerTask sets the owner (who will receive signals) to a specified task. +// Only this owner will receive signals. +func (a *FileAsync) SetOwnerTask(requester *kernel.Task, recipient *kernel.Task) { + a.mu.Lock() + defer a.mu.Unlock() + a.requester = requester.Credentials() + a.recipientT = recipient + a.recipientTG = nil + a.recipientPG = nil +} + +// SetOwnerThreadGroup sets the owner (who will receive signals) to a specified +// thread group. Only this owner will receive signals. +func (a *FileAsync) SetOwnerThreadGroup(requester *kernel.Task, recipient *kernel.ThreadGroup) { + a.mu.Lock() + defer a.mu.Unlock() + a.requester = requester.Credentials() + a.recipientT = nil + a.recipientTG = recipient + a.recipientPG = nil +} + +// SetOwnerProcessGroup sets the owner (who will receive signals) to a +// specified process group. Only this owner will receive signals. +func (a *FileAsync) SetOwnerProcessGroup(requester *kernel.Task, recipient *kernel.ProcessGroup) { + a.mu.Lock() + defer a.mu.Unlock() + a.requester = requester.Credentials() + a.recipientT = nil + a.recipientTG = nil + a.recipientPG = recipient +} + +// ClearOwner unsets the current signal recipient. +func (a *FileAsync) ClearOwner() { + a.mu.Lock() + defer a.mu.Unlock() + a.requester = nil + a.recipientT = nil + a.recipientTG = nil + a.recipientPG = nil +} |