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Diffstat (limited to 'runsc/container/container.go')
| -rw-r--r-- | runsc/container/container.go | 1171 |
1 files changed, 1171 insertions, 0 deletions
diff --git a/runsc/container/container.go b/runsc/container/container.go new file mode 100644 index 000000000..6d297d0df --- /dev/null +++ b/runsc/container/container.go @@ -0,0 +1,1171 @@ +// 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 container creates and manipulates containers. +package container + +import ( + "context" + "errors" + "fmt" + "io/ioutil" + "os" + "os/exec" + "regexp" + "strconv" + "strings" + "syscall" + "time" + + "github.com/cenkalti/backoff" + specs "github.com/opencontainers/runtime-spec/specs-go" + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/cleanup" + "gvisor.dev/gvisor/pkg/log" + "gvisor.dev/gvisor/pkg/sentry/control" + "gvisor.dev/gvisor/pkg/sentry/sighandling" + "gvisor.dev/gvisor/runsc/boot" + "gvisor.dev/gvisor/runsc/cgroup" + "gvisor.dev/gvisor/runsc/sandbox" + "gvisor.dev/gvisor/runsc/specutils" +) + +// validateID validates the container id. +func validateID(id string) error { + // See libcontainer/factory_linux.go. + idRegex := regexp.MustCompile(`^[\w+-\.]+$`) + if !idRegex.MatchString(id) { + return fmt.Errorf("invalid container id: %v", id) + } + return nil +} + +// Container represents a containerized application. When running, the +// container is associated with a single Sandbox. +// +// Container metadata can be saved and loaded to disk. Within a root directory, +// we maintain subdirectories for each container named with the container id. +// The container metadata is stored as a json within the container directory +// in a file named "meta.json". This metadata format is defined by us and is +// not part of the OCI spec. +// +// Containers must write their metadata files after any change to their internal +// states. The entire container directory is deleted when the container is +// destroyed. +// +// When the container is stopped, all processes that belong to the container +// must be stopped before Destroy() returns. containerd makes roughly the +// following calls to stop a container: +// - First it attempts to kill the container process with +// 'runsc kill SIGTERM'. After some time, it escalates to SIGKILL. In a +// separate thread, it's waiting on the container. As soon as the wait +// returns, it moves on to the next step: +// - It calls 'runsc kill --all SIGKILL' to stop every process that belongs to +// the container. 'kill --all SIGKILL' waits for all processes before +// returning. +// - Containerd waits for stdin, stdout and stderr to drain and be closed. +// - It calls 'runsc delete'. runc implementation kills --all SIGKILL once +// again just to be sure, waits, and then proceeds with remaining teardown. +// +type Container struct { + // ID is the container ID. + ID string `json:"id"` + + // Spec is the OCI runtime spec that configures this container. + Spec *specs.Spec `json:"spec"` + + // BundleDir is the directory containing the container bundle. + BundleDir string `json:"bundleDir"` + + // CreatedAt is the time the container was created. + CreatedAt time.Time `json:"createdAt"` + + // Owner is the container owner. + Owner string `json:"owner"` + + // ConsoleSocket is the path to a unix domain socket that will receive + // the console FD. + ConsoleSocket string `json:"consoleSocket"` + + // Status is the current container Status. + Status Status `json:"status"` + + // GoferPid is the PID of the gofer running along side the sandbox. May + // be 0 if the gofer has been killed. + GoferPid int `json:"goferPid"` + + // Sandbox is the sandbox this container is running in. It's set when the + // container is created and reset when the sandbox is destroyed. + Sandbox *sandbox.Sandbox `json:"sandbox"` + + // Saver handles load from/save to the state file safely from multiple + // processes. + Saver StateFile `json:"saver"` + + // + // Fields below this line are not saved in the state file and will not + // be preserved across commands. + // + + // goferIsChild is set if a gofer process is a child of the current process. + // + // This field isn't saved to json, because only a creator of a gofer + // process will have it as a child process. + goferIsChild bool +} + +// loadSandbox loads all containers that belong to the sandbox with the given +// ID. +func loadSandbox(rootDir, id string) ([]*Container, error) { + cids, err := List(rootDir) + if err != nil { + return nil, err + } + + // Load the container metadata. + var containers []*Container + for _, cid := range cids { + container, err := Load(rootDir, cid) + if err != nil { + // Container file may not exist if it raced with creation/deletion or + // directory was left behind. Load provides a snapshot in time, so it's + // fine to skip it. + if os.IsNotExist(err) { + continue + } + return nil, fmt.Errorf("loading container %q: %v", id, err) + } + if container.Sandbox.ID == id { + containers = append(containers, container) + } + } + return containers, nil +} + +// Load loads a container with the given id from a metadata file. partialID may +// be an abbreviation of the full container id, in which case Load loads the +// container to which id unambiguously refers to. Returns ErrNotExist if +// container doesn't exist. +func Load(rootDir, partialID string) (*Container, error) { + log.Debugf("Load container %q %q", rootDir, partialID) + if err := validateID(partialID); err != nil { + return nil, fmt.Errorf("validating id: %v", err) + } + + id, err := findContainerID(rootDir, partialID) + if err != nil { + // Preserve error so that callers can distinguish 'not found' errors. + return nil, err + } + + state := StateFile{ + RootDir: rootDir, + ID: id, + } + defer state.close() + + c := &Container{} + if err := state.load(c); err != nil { + if os.IsNotExist(err) { + // Preserve error so that callers can distinguish 'not found' errors. + return nil, err + } + return nil, fmt.Errorf("reading container metadata file %q: %v", state.statePath(), err) + } + + // If the status is "Running" or "Created", check that the sandbox + // process still exists, and set it to Stopped if it does not. + // + // This is inherently racy. + if c.Status == Running || c.Status == Created { + // Check if the sandbox process is still running. + if !c.isSandboxRunning() { + // Sandbox no longer exists, so this container definitely does not exist. + c.changeStatus(Stopped) + } else if c.Status == Running { + // Container state should reflect the actual state of the application, so + // we don't consider gofer process here. + if err := c.SignalContainer(syscall.Signal(0), false); err != nil { + c.changeStatus(Stopped) + } + } + } + + return c, nil +} + +func findContainerID(rootDir, partialID string) (string, error) { + // Check whether the id fully specifies an existing container. + stateFile := buildStatePath(rootDir, partialID) + if _, err := os.Stat(stateFile); err == nil { + return partialID, nil + } + + // Now see whether id could be an abbreviation of exactly 1 of the + // container ids. If id is ambiguous (it could match more than 1 + // container), it is an error. + ids, err := List(rootDir) + if err != nil { + return "", err + } + rv := "" + for _, id := range ids { + if strings.HasPrefix(id, partialID) { + if rv != "" { + return "", fmt.Errorf("id %q is ambiguous and could refer to multiple containers: %q, %q", partialID, rv, id) + } + rv = id + } + } + if rv == "" { + return "", os.ErrNotExist + } + log.Debugf("abbreviated id %q resolves to full id %q", partialID, rv) + return rv, nil +} + +// Args is used to configure a new container. +type Args struct { + // ID is the container unique identifier. + ID string + + // Spec is the OCI spec that describes the container. + Spec *specs.Spec + + // BundleDir is the directory containing the container bundle. + BundleDir string + + // ConsoleSocket is the path to a unix domain socket that will receive + // the console FD. It may be empty. + ConsoleSocket string + + // PIDFile is the filename where the container's root process PID will be + // written to. It may be empty. + PIDFile string + + // UserLog is the filename to send user-visible logs to. It may be empty. + // + // It only applies for the init container. + UserLog string + + // Attached indicates that the sandbox lifecycle is attached with the caller. + // If the caller exits, the sandbox should exit too. + // + // It only applies for the init container. + Attached bool +} + +// New creates the container in a new Sandbox process, unless the metadata +// indicates that an existing Sandbox should be used. The caller must call +// Destroy() on the container. +func New(conf *boot.Config, args Args) (*Container, error) { + log.Debugf("Create container %q in root dir: %s", args.ID, conf.RootDir) + if err := validateID(args.ID); err != nil { + return nil, err + } + + if err := os.MkdirAll(conf.RootDir, 0711); err != nil { + return nil, fmt.Errorf("creating container root directory %q: %v", conf.RootDir, err) + } + + c := &Container{ + ID: args.ID, + Spec: args.Spec, + ConsoleSocket: args.ConsoleSocket, + BundleDir: args.BundleDir, + Status: Creating, + CreatedAt: time.Now(), + Owner: os.Getenv("USER"), + Saver: StateFile{ + RootDir: conf.RootDir, + ID: args.ID, + }, + } + // The Cleanup object cleans up partially created containers when an error + // occurs. Any errors occurring during cleanup itself are ignored. + cu := cleanup.Make(func() { _ = c.Destroy() }) + defer cu.Clean() + + // Lock the container metadata file to prevent concurrent creations of + // containers with the same id. + if err := c.Saver.lockForNew(); err != nil { + return nil, err + } + defer c.Saver.unlock() + + // If the metadata annotations indicate that this container should be + // started in an existing sandbox, we must do so. The metadata will + // indicate the ID of the sandbox, which is the same as the ID of the + // init container in the sandbox. + if isRoot(args.Spec) { + log.Debugf("Creating new sandbox for container %q", args.ID) + + // Create and join cgroup before processes are created to ensure they are + // part of the cgroup from the start (and all their children processes). + cg, err := cgroup.New(args.Spec) + if err != nil { + return nil, err + } + if cg != nil { + // If there is cgroup config, install it before creating sandbox process. + if err := cg.Install(args.Spec.Linux.Resources); err != nil { + return nil, fmt.Errorf("configuring cgroup: %v", err) + } + } + if err := runInCgroup(cg, func() error { + ioFiles, specFile, err := c.createGoferProcess(args.Spec, conf, args.BundleDir) + if err != nil { + return err + } + + // Start a new sandbox for this container. Any errors after this point + // must destroy the container. + sandArgs := &sandbox.Args{ + ID: args.ID, + Spec: args.Spec, + BundleDir: args.BundleDir, + ConsoleSocket: args.ConsoleSocket, + UserLog: args.UserLog, + IOFiles: ioFiles, + MountsFile: specFile, + Cgroup: cg, + Attached: args.Attached, + } + sand, err := sandbox.New(conf, sandArgs) + if err != nil { + return err + } + c.Sandbox = sand + return nil + + }); err != nil { + return nil, err + } + } else { + // This is sort of confusing. For a sandbox with a root + // container and a child container in it, runsc sees: + // * A container struct whose sandbox ID is equal to the + // container ID. This is the root container that is tied to + // the creation of the sandbox. + // * A container struct whose sandbox ID is equal to the above + // container/sandbox ID, but that has a different container + // ID. This is the child container. + sbid, ok := specutils.SandboxID(args.Spec) + if !ok { + return nil, fmt.Errorf("no sandbox ID found when creating container") + } + log.Debugf("Creating new container %q in sandbox %q", c.ID, sbid) + + // Find the sandbox associated with this ID. + sb, err := Load(conf.RootDir, sbid) + if err != nil { + return nil, err + } + c.Sandbox = sb.Sandbox + if err := c.Sandbox.CreateContainer(c.ID); err != nil { + return nil, err + } + } + c.changeStatus(Created) + + // Save the metadata file. + if err := c.saveLocked(); err != nil { + return nil, err + } + + // Write the PID file. Containerd considers the create complete after + // this file is created, so it must be the last thing we do. + if args.PIDFile != "" { + if err := ioutil.WriteFile(args.PIDFile, []byte(strconv.Itoa(c.SandboxPid())), 0644); err != nil { + return nil, fmt.Errorf("error writing PID file: %v", err) + } + } + + cu.Release() + return c, nil +} + +// Start starts running the containerized process inside the sandbox. +func (c *Container) Start(conf *boot.Config) error { + log.Debugf("Start container %q", c.ID) + + if err := c.Saver.lock(); err != nil { + return err + } + unlock := cleanup.Make(func() { c.Saver.unlock() }) + defer unlock.Clean() + + if err := c.requireStatus("start", Created); err != nil { + return err + } + + // "If any prestart hook fails, the runtime MUST generate an error, + // stop and destroy the container" -OCI spec. + if c.Spec.Hooks != nil { + if err := executeHooks(c.Spec.Hooks.Prestart, c.State()); err != nil { + return err + } + } + + if isRoot(c.Spec) { + if err := c.Sandbox.StartRoot(c.Spec, conf); err != nil { + return err + } + } else { + // Join cgroup to start gofer process to ensure it's part of the cgroup from + // the start (and all their children processes). + if err := runInCgroup(c.Sandbox.Cgroup, func() error { + // Create the gofer process. + ioFiles, mountsFile, err := c.createGoferProcess(c.Spec, conf, c.BundleDir) + if err != nil { + return err + } + defer mountsFile.Close() + + cleanMounts, err := specutils.ReadMounts(mountsFile) + if err != nil { + return fmt.Errorf("reading mounts file: %v", err) + } + c.Spec.Mounts = cleanMounts + + return c.Sandbox.StartContainer(c.Spec, conf, c.ID, ioFiles) + }); err != nil { + return err + } + } + + // "If any poststart hook fails, the runtime MUST log a warning, but + // the remaining hooks and lifecycle continue as if the hook had + // succeeded" -OCI spec. + if c.Spec.Hooks != nil { + executeHooksBestEffort(c.Spec.Hooks.Poststart, c.State()) + } + + c.changeStatus(Running) + if err := c.saveLocked(); err != nil { + return err + } + + // Release lock before adjusting OOM score because the lock is acquired there. + unlock.Clean() + + // Adjust the oom_score_adj for sandbox. This must be done after saveLocked(). + if err := adjustSandboxOOMScoreAdj(c.Sandbox, c.Saver.RootDir, false); err != nil { + return err + } + + // Set container's oom_score_adj to the gofer since it is dedicated to + // the container, in case the gofer uses up too much memory. + return c.adjustGoferOOMScoreAdj() +} + +// Restore takes a container and replaces its kernel and file system +// to restore a container from its state file. +func (c *Container) Restore(spec *specs.Spec, conf *boot.Config, restoreFile string) error { + log.Debugf("Restore container %q", c.ID) + if err := c.Saver.lock(); err != nil { + return err + } + defer c.Saver.unlock() + + if err := c.requireStatus("restore", Created); err != nil { + return err + } + + // "If any prestart hook fails, the runtime MUST generate an error, + // stop and destroy the container" -OCI spec. + if c.Spec.Hooks != nil { + if err := executeHooks(c.Spec.Hooks.Prestart, c.State()); err != nil { + return err + } + } + + if err := c.Sandbox.Restore(c.ID, spec, conf, restoreFile); err != nil { + return err + } + c.changeStatus(Running) + return c.saveLocked() +} + +// Run is a helper that calls Create + Start + Wait. +func Run(conf *boot.Config, args Args) (syscall.WaitStatus, error) { + log.Debugf("Run container %q in root dir: %s", args.ID, conf.RootDir) + c, err := New(conf, args) + if err != nil { + return 0, fmt.Errorf("creating container: %v", err) + } + // Clean up partially created container if an error occurs. + // Any errors returned by Destroy() itself are ignored. + cu := cleanup.Make(func() { + c.Destroy() + }) + defer cu.Clean() + + if conf.RestoreFile != "" { + log.Debugf("Restore: %v", conf.RestoreFile) + if err := c.Restore(args.Spec, conf, conf.RestoreFile); err != nil { + return 0, fmt.Errorf("starting container: %v", err) + } + } else { + if err := c.Start(conf); err != nil { + return 0, fmt.Errorf("starting container: %v", err) + } + } + if args.Attached { + return c.Wait() + } + cu.Release() + return 0, nil +} + +// Execute runs the specified command in the container. It returns the PID of +// the newly created process. +func (c *Container) Execute(args *control.ExecArgs) (int32, error) { + log.Debugf("Execute in container %q, args: %+v", c.ID, args) + if err := c.requireStatus("execute in", Created, Running); err != nil { + return 0, err + } + args.ContainerID = c.ID + return c.Sandbox.Execute(args) +} + +// Event returns events for the container. +func (c *Container) Event() (*boot.Event, error) { + log.Debugf("Getting events for container %q", c.ID) + if err := c.requireStatus("get events for", Created, Running, Paused); err != nil { + return nil, err + } + return c.Sandbox.Event(c.ID) +} + +// SandboxPid returns the Pid of the sandbox the container is running in, or -1 if the +// container is not running. +func (c *Container) SandboxPid() int { + if err := c.requireStatus("get PID", Created, Running, Paused); err != nil { + return -1 + } + return c.Sandbox.Pid +} + +// Wait waits for the container to exit, and returns its WaitStatus. +// Call to wait on a stopped container is needed to retrieve the exit status +// and wait returns immediately. +func (c *Container) Wait() (syscall.WaitStatus, error) { + log.Debugf("Wait on container %q", c.ID) + return c.Sandbox.Wait(c.ID) +} + +// WaitRootPID waits for process 'pid' in the sandbox's PID namespace and +// returns its WaitStatus. +func (c *Container) WaitRootPID(pid int32) (syscall.WaitStatus, error) { + log.Debugf("Wait on PID %d in sandbox %q", pid, c.Sandbox.ID) + if !c.isSandboxRunning() { + return 0, fmt.Errorf("sandbox is not running") + } + return c.Sandbox.WaitPID(c.Sandbox.ID, pid) +} + +// WaitPID waits for process 'pid' in the container's PID namespace and returns +// its WaitStatus. +func (c *Container) WaitPID(pid int32) (syscall.WaitStatus, error) { + log.Debugf("Wait on PID %d in container %q", pid, c.ID) + if !c.isSandboxRunning() { + return 0, fmt.Errorf("sandbox is not running") + } + return c.Sandbox.WaitPID(c.ID, pid) +} + +// SignalContainer sends the signal to the container. If all is true and signal +// is SIGKILL, then waits for all processes to exit before returning. +// SignalContainer returns an error if the container is already stopped. +// TODO(b/113680494): Distinguish different error types. +func (c *Container) SignalContainer(sig syscall.Signal, all bool) error { + log.Debugf("Signal container %q: %v", c.ID, sig) + // Signaling container in Stopped state is allowed. When all=false, + // an error will be returned anyway; when all=true, this allows + // sending signal to other processes inside the container even + // after the init process exits. This is especially useful for + // container cleanup. + if err := c.requireStatus("signal", Running, Stopped); err != nil { + return err + } + if !c.isSandboxRunning() { + return fmt.Errorf("sandbox is not running") + } + return c.Sandbox.SignalContainer(c.ID, sig, all) +} + +// SignalProcess sends sig to a specific process in the container. +func (c *Container) SignalProcess(sig syscall.Signal, pid int32) error { + log.Debugf("Signal process %d in container %q: %v", pid, c.ID, sig) + if err := c.requireStatus("signal a process inside", Running); err != nil { + return err + } + if !c.isSandboxRunning() { + return fmt.Errorf("sandbox is not running") + } + return c.Sandbox.SignalProcess(c.ID, int32(pid), sig, false) +} + +// ForwardSignals forwards all signals received by the current process to the +// container process inside the sandbox. It returns a function that will stop +// forwarding signals. +func (c *Container) ForwardSignals(pid int32, fgProcess bool) func() { + log.Debugf("Forwarding all signals to container %q PID %d fgProcess=%t", c.ID, pid, fgProcess) + stop := sighandling.StartSignalForwarding(func(sig linux.Signal) { + log.Debugf("Forwarding signal %d to container %q PID %d fgProcess=%t", sig, c.ID, pid, fgProcess) + if err := c.Sandbox.SignalProcess(c.ID, pid, syscall.Signal(sig), fgProcess); err != nil { + log.Warningf("error forwarding signal %d to container %q: %v", sig, c.ID, err) + } + }) + return func() { + log.Debugf("Done forwarding signals to container %q PID %d fgProcess=%t", c.ID, pid, fgProcess) + stop() + } +} + +// Checkpoint sends the checkpoint call to the container. +// The statefile will be written to f, the file at the specified image-path. +func (c *Container) Checkpoint(f *os.File) error { + log.Debugf("Checkpoint container %q", c.ID) + if err := c.requireStatus("checkpoint", Created, Running, Paused); err != nil { + return err + } + return c.Sandbox.Checkpoint(c.ID, f) +} + +// Pause suspends the container and its kernel. +// The call only succeeds if the container's status is created or running. +func (c *Container) Pause() error { + log.Debugf("Pausing container %q", c.ID) + if err := c.Saver.lock(); err != nil { + return err + } + defer c.Saver.unlock() + + if c.Status != Created && c.Status != Running { + return fmt.Errorf("cannot pause container %q in state %v", c.ID, c.Status) + } + + if err := c.Sandbox.Pause(c.ID); err != nil { + return fmt.Errorf("pausing container: %v", err) + } + c.changeStatus(Paused) + return c.saveLocked() +} + +// Resume unpauses the container and its kernel. +// The call only succeeds if the container's status is paused. +func (c *Container) Resume() error { + log.Debugf("Resuming container %q", c.ID) + if err := c.Saver.lock(); err != nil { + return err + } + defer c.Saver.unlock() + + if c.Status != Paused { + return fmt.Errorf("cannot resume container %q in state %v", c.ID, c.Status) + } + if err := c.Sandbox.Resume(c.ID); err != nil { + return fmt.Errorf("resuming container: %v", err) + } + c.changeStatus(Running) + return c.saveLocked() +} + +// State returns the metadata of the container. +func (c *Container) State() specs.State { + return specs.State{ + Version: specs.Version, + ID: c.ID, + Status: c.Status.String(), + Pid: c.SandboxPid(), + Bundle: c.BundleDir, + } +} + +// Processes retrieves the list of processes and associated metadata inside a +// container. +func (c *Container) Processes() ([]*control.Process, error) { + if err := c.requireStatus("get processes of", Running, Paused); err != nil { + return nil, err + } + return c.Sandbox.Processes(c.ID) +} + +// Destroy stops all processes and frees all resources associated with the +// container. +func (c *Container) Destroy() error { + log.Debugf("Destroy container %q", c.ID) + + if err := c.Saver.lock(); err != nil { + return err + } + defer func() { + c.Saver.unlock() + c.Saver.close() + }() + + // Stored for later use as stop() sets c.Sandbox to nil. + sb := c.Sandbox + + // We must perform the following cleanup steps: + // * stop the container and gofer processes, + // * remove the container filesystem on the host, and + // * delete the container metadata directory. + // + // It's possible for one or more of these steps to fail, but we should + // do our best to perform all of the cleanups. Hence, we keep a slice + // of errors return their concatenation. + var errs []string + if err := c.stop(); err != nil { + err = fmt.Errorf("stopping container: %v", err) + log.Warningf("%v", err) + errs = append(errs, err.Error()) + } + + if err := c.Saver.destroy(); err != nil { + err = fmt.Errorf("deleting container state files: %v", err) + log.Warningf("%v", err) + errs = append(errs, err.Error()) + } + + c.changeStatus(Stopped) + + // Adjust oom_score_adj for the sandbox. This must be done after the container + // is stopped and the directory at c.Root is removed. Adjustment can be + // skipped if the root container is exiting, because it brings down the entire + // sandbox. + // + // Use 'sb' to tell whether it has been executed before because Destroy must + // be idempotent. + if sb != nil && !isRoot(c.Spec) { + if err := adjustSandboxOOMScoreAdj(sb, c.Saver.RootDir, true); err != nil { + errs = append(errs, err.Error()) + } + } + + // "If any poststop hook fails, the runtime MUST log a warning, but the + // remaining hooks and lifecycle continue as if the hook had + // succeeded" - OCI spec. + // + // Based on the OCI, "The post-stop hooks MUST be called after the container + // is deleted but before the delete operation returns" + // Run it here to: + // 1) Conform to the OCI. + // 2) Make sure it only runs once, because the root has been deleted, the + // container can't be loaded again. + if c.Spec.Hooks != nil { + executeHooksBestEffort(c.Spec.Hooks.Poststop, c.State()) + } + + if len(errs) == 0 { + return nil + } + return fmt.Errorf(strings.Join(errs, "\n")) +} + +// saveLocked saves the container metadata to a file. +// +// Precondition: container must be locked with container.lock(). +func (c *Container) saveLocked() error { + log.Debugf("Save container %q", c.ID) + if err := c.Saver.saveLocked(c); err != nil { + return fmt.Errorf("saving container metadata: %v", err) + } + return nil +} + +// stop stops the container (for regular containers) or the sandbox (for +// root containers), and waits for the container or sandbox and the gofer +// to stop. If any of them doesn't stop before timeout, an error is returned. +func (c *Container) stop() error { + var cgroup *cgroup.Cgroup + + if c.Sandbox != nil { + log.Debugf("Destroying container %q", c.ID) + if err := c.Sandbox.DestroyContainer(c.ID); err != nil { + return fmt.Errorf("destroying container %q: %v", c.ID, err) + } + // Only uninstall cgroup for sandbox stop. + if c.Sandbox.IsRootContainer(c.ID) { + cgroup = c.Sandbox.Cgroup + } + // Only set sandbox to nil after it has been told to destroy the container. + c.Sandbox = nil + } + + // Try killing gofer if it does not exit with container. + if c.GoferPid != 0 { + log.Debugf("Killing gofer for container %q, PID: %d", c.ID, c.GoferPid) + if err := syscall.Kill(c.GoferPid, syscall.SIGKILL); err != nil { + // The gofer may already be stopped, log the error. + log.Warningf("Error sending signal %d to gofer %d: %v", syscall.SIGKILL, c.GoferPid, err) + } + } + + if err := c.waitForStopped(); err != nil { + return err + } + + // Gofer is running in cgroups, so Cgroup.Uninstall has to be called after it. + if cgroup != nil { + if err := cgroup.Uninstall(); err != nil { + return err + } + } + return nil +} + +func (c *Container) waitForStopped() error { + ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second) + defer cancel() + b := backoff.WithContext(backoff.NewConstantBackOff(100*time.Millisecond), ctx) + op := func() error { + if c.isSandboxRunning() { + if err := c.SignalContainer(syscall.Signal(0), false); err == nil { + return fmt.Errorf("container is still running") + } + } + if c.GoferPid == 0 { + return nil + } + if c.goferIsChild { + // The gofer process is a child of the current process, + // so we can wait it and collect its zombie. + wpid, err := syscall.Wait4(int(c.GoferPid), nil, syscall.WNOHANG, nil) + if err != nil { + return fmt.Errorf("error waiting the gofer process: %v", err) + } + if wpid == 0 { + return fmt.Errorf("gofer is still running") + } + + } else if err := syscall.Kill(c.GoferPid, 0); err == nil { + return fmt.Errorf("gofer is still running") + } + c.GoferPid = 0 + return nil + } + return backoff.Retry(op, b) +} + +func (c *Container) createGoferProcess(spec *specs.Spec, conf *boot.Config, bundleDir string) ([]*os.File, *os.File, error) { + // Start with the general config flags. + args := conf.ToFlags() + + var goferEnds []*os.File + + // nextFD is the next available file descriptor for the gofer process. + // It starts at 3 because 0-2 are used by stdin/stdout/stderr. + nextFD := 3 + + if conf.LogFilename != "" { + logFile, err := os.OpenFile(conf.LogFilename, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644) + if err != nil { + return nil, nil, fmt.Errorf("opening log file %q: %v", conf.LogFilename, err) + } + defer logFile.Close() + goferEnds = append(goferEnds, logFile) + args = append(args, "--log-fd="+strconv.Itoa(nextFD)) + nextFD++ + } + + if conf.DebugLog != "" { + test := "" + if len(conf.TestOnlyTestNameEnv) != 0 { + // Fetch test name if one is provided and the test only flag was set. + if t, ok := specutils.EnvVar(spec.Process.Env, conf.TestOnlyTestNameEnv); ok { + test = t + } + } + debugLogFile, err := specutils.DebugLogFile(conf.DebugLog, "gofer", test) + if err != nil { + return nil, nil, fmt.Errorf("opening debug log file in %q: %v", conf.DebugLog, err) + } + defer debugLogFile.Close() + goferEnds = append(goferEnds, debugLogFile) + args = append(args, "--debug-log-fd="+strconv.Itoa(nextFD)) + nextFD++ + } + + args = append(args, "gofer", "--bundle", bundleDir) + if conf.Overlay { + args = append(args, "--panic-on-write=true") + } + + // Open the spec file to donate to the sandbox. + specFile, err := specutils.OpenSpec(bundleDir) + if err != nil { + return nil, nil, fmt.Errorf("opening spec file: %v", err) + } + defer specFile.Close() + goferEnds = append(goferEnds, specFile) + args = append(args, "--spec-fd="+strconv.Itoa(nextFD)) + nextFD++ + + // Create pipe that allows gofer to send mount list to sandbox after all paths + // have been resolved. + mountsSand, mountsGofer, err := os.Pipe() + if err != nil { + return nil, nil, err + } + defer mountsGofer.Close() + goferEnds = append(goferEnds, mountsGofer) + args = append(args, fmt.Sprintf("--mounts-fd=%d", nextFD)) + nextFD++ + + // Add root mount and then add any other additional mounts. + mountCount := 1 + for _, m := range spec.Mounts { + if specutils.Is9PMount(m) { + mountCount++ + } + } + + sandEnds := make([]*os.File, 0, mountCount) + for i := 0; i < mountCount; i++ { + fds, err := syscall.Socketpair(syscall.AF_UNIX, syscall.SOCK_STREAM|syscall.SOCK_CLOEXEC, 0) + if err != nil { + return nil, nil, err + } + sandEnds = append(sandEnds, os.NewFile(uintptr(fds[0]), "sandbox IO FD")) + + goferEnd := os.NewFile(uintptr(fds[1]), "gofer IO FD") + defer goferEnd.Close() + goferEnds = append(goferEnds, goferEnd) + + args = append(args, fmt.Sprintf("--io-fds=%d", nextFD)) + nextFD++ + } + + binPath := specutils.ExePath + cmd := exec.Command(binPath, args...) + cmd.ExtraFiles = goferEnds + cmd.Args[0] = "runsc-gofer" + + // Enter new namespaces to isolate from the rest of the system. Don't unshare + // cgroup because gofer is added to a cgroup in the caller's namespace. + nss := []specs.LinuxNamespace{ + {Type: specs.IPCNamespace}, + {Type: specs.MountNamespace}, + {Type: specs.NetworkNamespace}, + {Type: specs.PIDNamespace}, + {Type: specs.UTSNamespace}, + } + + // Setup any uid/gid mappings, and create or join the configured user + // namespace so the gofer's view of the filesystem aligns with the + // users in the sandbox. + userNS := specutils.FilterNS([]specs.LinuxNamespaceType{specs.UserNamespace}, spec) + nss = append(nss, userNS...) + specutils.SetUIDGIDMappings(cmd, spec) + if len(userNS) != 0 { + // We need to set UID and GID to have capabilities in a new user namespace. + cmd.SysProcAttr.Credential = &syscall.Credential{Uid: 0, Gid: 0} + } + + // Start the gofer in the given namespace. + log.Debugf("Starting gofer: %s %v", binPath, args) + if err := specutils.StartInNS(cmd, nss); err != nil { + return nil, nil, fmt.Errorf("Gofer: %v", err) + } + log.Infof("Gofer started, PID: %d", cmd.Process.Pid) + c.GoferPid = cmd.Process.Pid + c.goferIsChild = true + return sandEnds, mountsSand, nil +} + +// changeStatus transitions from one status to another ensuring that the +// transition is valid. +func (c *Container) changeStatus(s Status) { + switch s { + case Creating: + // Initial state, never transitions to it. + panic(fmt.Sprintf("invalid state transition: %v => %v", c.Status, s)) + + case Created: + if c.Status != Creating { + panic(fmt.Sprintf("invalid state transition: %v => %v", c.Status, s)) + } + if c.Sandbox == nil { + panic("sandbox cannot be nil") + } + + case Paused: + if c.Status != Running { + panic(fmt.Sprintf("invalid state transition: %v => %v", c.Status, s)) + } + if c.Sandbox == nil { + panic("sandbox cannot be nil") + } + + case Running: + if c.Status != Created && c.Status != Paused { + panic(fmt.Sprintf("invalid state transition: %v => %v", c.Status, s)) + } + if c.Sandbox == nil { + panic("sandbox cannot be nil") + } + + case Stopped: + if c.Status != Creating && c.Status != Created && c.Status != Running && c.Status != Stopped { + panic(fmt.Sprintf("invalid state transition: %v => %v", c.Status, s)) + } + + default: + panic(fmt.Sprintf("invalid new state: %v", s)) + } + c.Status = s +} + +func (c *Container) isSandboxRunning() bool { + return c.Sandbox != nil && c.Sandbox.IsRunning() +} + +func (c *Container) requireStatus(action string, statuses ...Status) error { + for _, s := range statuses { + if c.Status == s { + return nil + } + } + return fmt.Errorf("cannot %s container %q in state %s", action, c.ID, c.Status) +} + +func isRoot(spec *specs.Spec) bool { + return specutils.SpecContainerType(spec) != specutils.ContainerTypeContainer +} + +// runInCgroup executes fn inside the specified cgroup. If cg is nil, execute +// it in the current context. +func runInCgroup(cg *cgroup.Cgroup, fn func() error) error { + if cg == nil { + return fn() + } + restore, err := cg.Join() + defer restore() + if err != nil { + return err + } + return fn() +} + +// adjustGoferOOMScoreAdj sets the oom_store_adj for the container's gofer. +func (c *Container) adjustGoferOOMScoreAdj() error { + if c.GoferPid == 0 || c.Spec.Process.OOMScoreAdj == nil { + return nil + } + return setOOMScoreAdj(c.GoferPid, *c.Spec.Process.OOMScoreAdj) +} + +// adjustSandboxOOMScoreAdj sets the oom_score_adj for the sandbox. +// oom_score_adj is set to the lowest oom_score_adj among the containers +// running in the sandbox. +// +// TODO(gvisor.dev/issue/238): This call could race with other containers being +// created at the same time and end up setting the wrong oom_score_adj to the +// sandbox. Use rpc client to synchronize. +func adjustSandboxOOMScoreAdj(s *sandbox.Sandbox, rootDir string, destroy bool) error { + containers, err := loadSandbox(rootDir, s.ID) + if err != nil { + return fmt.Errorf("loading sandbox containers: %v", err) + } + + // Do nothing if the sandbox has been terminated. + if len(containers) == 0 { + return nil + } + + // Get the lowest score for all containers. + var lowScore int + scoreFound := false + if len(containers) == 1 && specutils.SpecContainerType(containers[0].Spec) == specutils.ContainerTypeUnspecified { + // This is a single-container sandbox. Set the oom_score_adj to + // the value specified in the OCI bundle. + if containers[0].Spec.Process.OOMScoreAdj != nil { + scoreFound = true + lowScore = *containers[0].Spec.Process.OOMScoreAdj + } + } else { + for _, container := range containers { + // Special multi-container support for CRI. Ignore the root + // container when calculating oom_score_adj for the sandbox because + // it is the infrastructure (pause) container and always has a very + // low oom_score_adj. + // + // We will use OOMScoreAdj in the single-container case where the + // containerd container-type annotation is not present. + if specutils.SpecContainerType(container.Spec) == specutils.ContainerTypeSandbox { + continue + } + + if container.Spec.Process.OOMScoreAdj != nil && (!scoreFound || *container.Spec.Process.OOMScoreAdj < lowScore) { + scoreFound = true + lowScore = *container.Spec.Process.OOMScoreAdj + } + } + } + + // If the container is destroyed and remaining containers have no + // oomScoreAdj specified then we must revert to the oom_score_adj of the + // parent process. + if !scoreFound && destroy { + ppid, err := specutils.GetParentPid(s.Pid) + if err != nil { + return fmt.Errorf("getting parent pid of sandbox pid %d: %v", s.Pid, err) + } + pScore, err := specutils.GetOOMScoreAdj(ppid) + if err != nil { + return fmt.Errorf("getting oom_score_adj of parent %d: %v", ppid, err) + } + + scoreFound = true + lowScore = pScore + } + + // Only set oom_score_adj if one of the containers has oom_score_adj set + // in the OCI bundle. If not, we need to inherit the parent process's + // oom_score_adj. + // See: https://github.com/opencontainers/runtime-spec/blob/master/config.md#linux-process + if !scoreFound { + return nil + } + + // Set the lowest of all containers oom_score_adj to the sandbox. + return setOOMScoreAdj(s.Pid, lowScore) +} + +// setOOMScoreAdj sets oom_score_adj to the given value for the given PID. +// /proc must be available and mounted read-write. scoreAdj should be between +// -1000 and 1000. It's a noop if the process has already exited. +func setOOMScoreAdj(pid int, scoreAdj int) error { + f, err := os.OpenFile(fmt.Sprintf("/proc/%d/oom_score_adj", pid), os.O_WRONLY, 0644) + if err != nil { + // Ignore NotExist errors because it can race with process exit. + if os.IsNotExist(err) { + log.Warningf("Process (%d) not found setting oom_score_adj", pid) + return nil + } + return err + } + defer f.Close() + if _, err := f.WriteString(strconv.Itoa(scoreAdj)); err != nil { + if errors.Is(err, syscall.ESRCH) { + log.Warningf("Process (%d) exited while setting oom_score_adj", pid) + return nil + } + return fmt.Errorf("setting oom_score_adj to %q: %v", scoreAdj, err) + } + return nil +} |