diff options
| -rw-r--r-- | runsc/cmd/boot.go | 75 | ||||
| -rw-r--r-- | runsc/sandbox/sandbox.go | 12 | ||||
| -rw-r--r-- | runsc/specutils/namespace.go | 3 |
3 files changed, 60 insertions, 30 deletions
diff --git a/runsc/cmd/boot.go b/runsc/cmd/boot.go index 0f3da69a0..0938944a6 100644 --- a/runsc/cmd/boot.go +++ b/runsc/cmd/boot.go @@ -23,6 +23,7 @@ import ( "github.com/google/subcommands" specs "github.com/opencontainers/runtime-spec/specs-go" + "golang.org/x/sys/unix" "gvisor.dev/gvisor/pkg/log" "gvisor.dev/gvisor/runsc/boot" "gvisor.dev/gvisor/runsc/boot/platforms" @@ -82,8 +83,13 @@ type Boot struct { // sandbox (e.g. gofer) and sent through this FD. mountsFD int - // pidns is set if the sanadbox is in its own pid namespace. + // pidns is set if the sandbox is in its own pid namespace. pidns bool + + // attached is set to true to kill the sandbox process when the parent process + // terminates. This flag is set when the command execve's itself because + // parent death signal doesn't propagate through execve when uid/gid changes. + attached bool } // Name implements subcommands.Command.Name. @@ -118,6 +124,7 @@ func (b *Boot) SetFlags(f *flag.FlagSet) { f.IntVar(&b.userLogFD, "user-log-fd", 0, "file descriptor to write user logs to. 0 means no logging.") f.IntVar(&b.startSyncFD, "start-sync-fd", -1, "required FD to used to synchronize sandbox startup") f.IntVar(&b.mountsFD, "mounts-fd", -1, "mountsFD is the file descriptor to read list of mounts after they have been resolved (direct paths, no symlinks).") + f.BoolVar(&b.attached, "attached", false, "if attached is true, kills the sandbox process when the parent process terminates") } // Execute implements subcommands.Command.Execute. It starts a sandbox in a @@ -133,29 +140,32 @@ func (b *Boot) Execute(_ context.Context, f *flag.FlagSet, args ...interface{}) conf := args[0].(*boot.Config) + if b.attached { + // Ensure this process is killed after parent process terminates when + // attached mode is enabled. In the unfortunate event that the parent + // terminates before this point, this process leaks. + if err := unix.Prctl(unix.PR_SET_PDEATHSIG, uintptr(unix.SIGKILL), 0, 0, 0); err != nil { + Fatalf("error setting parent death signal: %v", err) + } + } + if b.setUpRoot { if err := setUpChroot(b.pidns); err != nil { Fatalf("error setting up chroot: %v", err) } - if !b.applyCaps { - // Remove --setup-root arg to call myself. - var args []string - for _, arg := range os.Args { - if !strings.Contains(arg, "setup-root") { - args = append(args, arg) - } - } - if !conf.Rootless { - // Note that we've already read the spec from the spec FD, and - // we will read it again after the exec call. This works - // because the ReadSpecFromFile function seeks to the beginning - // of the file before reading. - if err := callSelfAsNobody(args); err != nil { - Fatalf("%v", err) - } - panic("callSelfAsNobody must never return success") + if !b.applyCaps && !conf.Rootless { + // Remove --apply-caps arg to call myself. It has already been done. + args := prepareArgs(b.attached, "setup-root") + + // Note that we've already read the spec from the spec FD, and + // we will read it again after the exec call. This works + // because the ReadSpecFromFile function seeks to the beginning + // of the file before reading. + if err := callSelfAsNobody(args); err != nil { + Fatalf("%v", err) } + panic("callSelfAsNobody must never return success") } } @@ -181,13 +191,9 @@ func (b *Boot) Execute(_ context.Context, f *flag.FlagSet, args ...interface{}) caps.Permitted = append(caps.Permitted, c) } - // Remove --apply-caps arg to call myself. - var args []string - for _, arg := range os.Args { - if !strings.Contains(arg, "setup-root") && !strings.Contains(arg, "apply-caps") { - args = append(args, arg) - } - } + // Remove --apply-caps and --setup-root arg to call myself. Both have + // already been done. + args := prepareArgs(b.attached, "setup-root", "apply-caps") // Note that we've already read the spec from the spec FD, and // we will read it again after the exec call. This works @@ -258,3 +264,22 @@ func (b *Boot) Execute(_ context.Context, f *flag.FlagSet, args ...interface{}) l.Destroy() return subcommands.ExitSuccess } + +func prepareArgs(attached bool, exclude ...string) []string { + var args []string + for _, arg := range os.Args { + for _, excl := range exclude { + if strings.Contains(arg, excl) { + goto skip + } + } + args = append(args, arg) + if attached && arg == "boot" { + // Strategicaly place "--attached" after the command. This is needed + // to ensure the new process is killed when the parent process terminates. + args = append(args, "--attached") + } + skip: + } + return args +} diff --git a/runsc/sandbox/sandbox.go b/runsc/sandbox/sandbox.go index 6177d6aa7..8de75ae57 100644 --- a/runsc/sandbox/sandbox.go +++ b/runsc/sandbox/sandbox.go @@ -701,6 +701,13 @@ func (s *Sandbox) createSandboxProcess(conf *boot.Config, args *Args, startSyncF nextFD++ } + if args.Attached { + // Kill sandbox if parent process exits in attached mode. + cmd.SysProcAttr.Pdeathsig = syscall.SIGKILL + // Tells boot that any process it creates must have pdeathsig set. + cmd.Args = append(cmd.Args, "--attached") + } + // Add container as the last argument. cmd.Args = append(cmd.Args, s.ID) @@ -709,11 +716,6 @@ func (s *Sandbox) createSandboxProcess(conf *boot.Config, args *Args, startSyncF log.Debugf("Donating FD %d: %q", i+3, f.Name()) } - if args.Attached { - // Kill sandbox if parent process exits in attached mode. - cmd.SysProcAttr.Pdeathsig = syscall.SIGKILL - } - log.Debugf("Starting sandbox: %s %v", binPath, cmd.Args) log.Debugf("SysProcAttr: %+v", cmd.SysProcAttr) if err := specutils.StartInNS(cmd, nss); err != nil { diff --git a/runsc/specutils/namespace.go b/runsc/specutils/namespace.go index c7dd3051c..60bb7b7ee 100644 --- a/runsc/specutils/namespace.go +++ b/runsc/specutils/namespace.go @@ -252,6 +252,9 @@ func MaybeRunAsRoot() error { }, Credential: &syscall.Credential{Uid: 0, Gid: 0}, GidMappingsEnableSetgroups: false, + + // Make sure child is killed when the parent terminates. + Pdeathsig: syscall.SIGKILL, } cmd.Env = os.Environ() |