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// Copyright 2018 Google Inc.
//
// 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 specutils contains utility functions for working with OCI runtime
// specs.
package specutils
import (
"encoding/json"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"strings"
"syscall"
"time"
specs "github.com/opencontainers/runtime-spec/specs-go"
"gvisor.googlesource.com/gvisor/pkg/abi/linux"
"gvisor.googlesource.com/gvisor/pkg/log"
"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/auth"
)
// LogSpec logs the spec in a human-friendly way.
func LogSpec(spec *specs.Spec) {
log.Debugf("Spec: %+v", spec)
log.Debugf("Spec.Hooks: %+v", spec.Hooks)
log.Debugf("Spec.Linux: %+v", spec.Linux)
log.Debugf("Spec.Process: %+v", spec.Process)
log.Debugf("Spec.Root: %+v", spec.Root)
}
// ReadSpec reads an OCI runtime spec from the given bundle directory.
//
// TODO: This should validate the spec.
func ReadSpec(bundleDir string) (*specs.Spec, error) {
// The spec file must be in "config.json" inside the bundle directory.
specFile := filepath.Join(bundleDir, "config.json")
specBytes, err := ioutil.ReadFile(specFile)
if err != nil {
return nil, fmt.Errorf("error reading spec from file %q: %v", specFile, err)
}
var spec specs.Spec
if err := json.Unmarshal(specBytes, &spec); err != nil {
return nil, fmt.Errorf("error unmarshaling spec from file %q: %v\n %s", specFile, err, string(specBytes))
}
return &spec, nil
}
// GetExecutablePath returns the absolute path to the executable, relative to
// the root. It searches the environment PATH for the first file that exists
// with the given name.
func GetExecutablePath(exec, root string, env []string) (string, error) {
exec = filepath.Clean(exec)
// Don't search PATH if exec is a path to a file (absolute or relative).
if strings.IndexByte(exec, '/') >= 0 {
return exec, nil
}
// Get the PATH from the environment.
const prefix = "PATH="
var path []string
for _, e := range env {
if strings.HasPrefix(e, prefix) {
path = strings.Split(strings.TrimPrefix(e, prefix), ":")
break
}
}
// Search the PATH for a file whose name matches the one we are looking
// for.
for _, p := range path {
abs := filepath.Join(root, p, exec)
if _, err := os.Stat(abs); err == nil {
// We found it! Return the path relative to the root.
return filepath.Join("/", p, exec), nil
}
}
// Could not find a suitable path, just return the original string.
log.Warningf("could not find executable %s in path %s", exec, path)
return exec, nil
}
// Capabilities takes in spec and returns a TaskCapabilities corresponding to
// the spec.
func Capabilities(specCaps *specs.LinuxCapabilities) (*auth.TaskCapabilities, error) {
var caps auth.TaskCapabilities
if specCaps != nil {
var err error
if caps.BoundingCaps, err = capsFromNames(specCaps.Bounding); err != nil {
return nil, err
}
if caps.EffectiveCaps, err = capsFromNames(specCaps.Effective); err != nil {
return nil, err
}
if caps.InheritableCaps, err = capsFromNames(specCaps.Inheritable); err != nil {
return nil, err
}
if caps.PermittedCaps, err = capsFromNames(specCaps.Permitted); err != nil {
return nil, err
}
// TODO: Support ambient capabilities.
}
return &caps, nil
}
var capFromName = map[string]linux.Capability{
"CAP_CHOWN": linux.CAP_CHOWN,
"CAP_DAC_OVERRIDE": linux.CAP_DAC_OVERRIDE,
"CAP_DAC_READ_SEARCH": linux.CAP_DAC_READ_SEARCH,
"CAP_FOWNER": linux.CAP_FOWNER,
"CAP_FSETID": linux.CAP_FSETID,
"CAP_KILL": linux.CAP_KILL,
"CAP_SETGID": linux.CAP_SETGID,
"CAP_SETUID": linux.CAP_SETUID,
"CAP_SETPCAP": linux.CAP_SETPCAP,
"CAP_LINUX_IMMUTABLE": linux.CAP_LINUX_IMMUTABLE,
"CAP_NET_BIND_SERVICE": linux.CAP_NET_BIND_SERVICE,
"CAP_NET_BROADCAST": linux.CAP_NET_BROADCAST,
"CAP_NET_ADMIN": linux.CAP_NET_ADMIN,
"CAP_NET_RAW": linux.CAP_NET_RAW,
"CAP_IPC_LOCK": linux.CAP_IPC_LOCK,
"CAP_IPC_OWNER": linux.CAP_IPC_OWNER,
"CAP_SYS_MODULE": linux.CAP_SYS_MODULE,
"CAP_SYS_RAWIO": linux.CAP_SYS_RAWIO,
"CAP_SYS_CHROOT": linux.CAP_SYS_CHROOT,
"CAP_SYS_PTRACE": linux.CAP_SYS_PTRACE,
"CAP_SYS_PACCT": linux.CAP_SYS_PACCT,
"CAP_SYS_ADMIN": linux.CAP_SYS_ADMIN,
"CAP_SYS_BOOT": linux.CAP_SYS_BOOT,
"CAP_SYS_NICE": linux.CAP_SYS_NICE,
"CAP_SYS_RESOURCE": linux.CAP_SYS_RESOURCE,
"CAP_SYS_TIME": linux.CAP_SYS_TIME,
"CAP_SYS_TTY_CONFIG": linux.CAP_SYS_TTY_CONFIG,
"CAP_MKNOD": linux.CAP_MKNOD,
"CAP_LEASE": linux.CAP_LEASE,
"CAP_AUDIT_WRITE": linux.CAP_AUDIT_WRITE,
"CAP_AUDIT_CONTROL": linux.CAP_AUDIT_CONTROL,
"CAP_SETFCAP": linux.CAP_SETFCAP,
"CAP_MAC_OVERRIDE": linux.CAP_MAC_OVERRIDE,
"CAP_MAC_ADMIN": linux.CAP_MAC_ADMIN,
"CAP_SYSLOG": linux.CAP_SYSLOG,
"CAP_WAKE_ALARM": linux.CAP_WAKE_ALARM,
"CAP_BLOCK_SUSPEND": linux.CAP_BLOCK_SUSPEND,
"CAP_AUDIT_READ": linux.CAP_AUDIT_READ,
}
func capsFromNames(names []string) (auth.CapabilitySet, error) {
var caps []linux.Capability
for _, n := range names {
c, ok := capFromName[n]
if !ok {
return 0, fmt.Errorf("unknown capability %q", n)
}
caps = append(caps, c)
}
return auth.CapabilitySetOfMany(caps), nil
}
// Is9PMount returns true if the given mount can be mounted as an external gofer.
func Is9PMount(m specs.Mount) bool {
return m.Type == "bind" && m.Source != "" && !strings.HasPrefix(m.Destination, "/dev")
}
// BinPath returns the real path to self, resolving symbolink links. This is done
// to make the process name appears as 'runsc', instead of 'exe'.
func BinPath() (string, error) {
binPath, err := filepath.EvalSymlinks("/proc/self/exe")
if err != nil {
return "", fmt.Errorf(`error resolving "/proc/self/exe" symlink: %v`, err)
}
return binPath, nil
}
// WaitForReady waits for a process to become ready. The process is ready when
// the 'ready' function returns true. It continues to wait if 'ready' returns
// false. It returns error on timeout, if the process stops or if 'ready' fails.
func WaitForReady(pid int, timeout time.Duration, ready func() (bool, error)) error {
backoff := 1 * time.Millisecond
for start := time.Now(); time.Now().Sub(start) < timeout; {
if ok, err := ready(); err != nil {
return err
} else if ok {
return nil
}
// Check if the process is still running.
var ws syscall.WaitStatus
var ru syscall.Rusage
child, err := syscall.Wait4(pid, &ws, syscall.WNOHANG, &ru)
if err != nil || child == pid {
return fmt.Errorf("process (%d) is not running, err: %v", pid, err)
}
// Process continues to run, backoff and retry.
time.Sleep(backoff)
backoff *= 2
if backoff > 1*time.Second {
backoff = 1 * time.Second
}
}
return fmt.Errorf("timed out waiting for process (%d)", pid)
}
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