Specify a memory file in platform.New().

PiperOrigin-RevId: 307941984

11 files changed, 78 insertions, 11 deletions

diff --git a/pkg/abi/linux/BUILD b/pkg/abi/linux/BUILD
index 322d1ccc4..59b0e138a 100644
--- a/pkg/abi/linux/BUILD
+++ b/pkg/abi/linux/BUILD
@@ -10,6 +10,7 @@ go_library(
     name = "linux",
     srcs = [
         "aio.go",
+        "arch_amd64.go",
         "audit.go",
         "bpf.go",
         "capability.go",
diff --git a/pkg/abi/linux/arch_amd64.go b/pkg/abi/linux/arch_amd64.go
new file mode 100644
index 000000000..0be31e755
--- /dev/null
+++ b/pkg/abi/linux/arch_amd64.go
@@ -0,0 +1,23 @@
+// Copyright 2020 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.
+
+// +build amd64
+
+package linux
+
+// Start and end addresses of the vsyscall page.
+const (
+	VSyscallStartAddr uint64 = 0xffffffffff600000
+	VSyscallEndAddr   uint64 = 0xffffffffff601000
+)
diff --git a/pkg/abi/linux/seccomp.go b/pkg/abi/linux/seccomp.go
index 4eeb5cd7a..d0607e256 100644
--- a/pkg/abi/linux/seccomp.go
+++ b/pkg/abi/linux/seccomp.go
@@ -63,3 +63,10 @@ func (a BPFAction) String() string {
 func (a BPFAction) Data() uint16 {
 	return uint16(a & SECCOMP_RET_DATA)
 }
+
+// SockFprog is sock_fprog taken from <linux/filter.h>.
+type SockFprog struct {
+	Len    uint16
+	pad    [6]byte
+	Filter *BPFInstruction
+}
diff --git a/pkg/flipcall/packet_window_allocator.go b/pkg/flipcall/packet_window_allocator.go
index ccb918fab..af9cc3d21 100644
--- a/pkg/flipcall/packet_window_allocator.go
+++ b/pkg/flipcall/packet_window_allocator.go
@@ -134,7 +134,7 @@ func (pwa *PacketWindowAllocator) Allocate(size int) (PacketWindowDescriptor, er
 	start := pwa.nextAlloc
 	pwa.nextAlloc = end
 	return PacketWindowDescriptor{
-		FD:     pwa.fd,
+		FD:     pwa.FD(),
 		Offset: start,
 		Length: size,
 	}, nil
@@ -158,7 +158,7 @@ func (pwa *PacketWindowAllocator) ensureFileSize(min int64) error {
 		}
 		newSize = newNewSize
 	}
-	if err := syscall.Ftruncate(pwa.fd, newSize); err != nil {
+	if err := syscall.Ftruncate(pwa.FD(), newSize); err != nil {
 		return fmt.Errorf("ftruncate failed: %v", err)
 	}
 	pwa.fileSize = newSize
diff --git a/pkg/seccomp/seccomp_unsafe.go b/pkg/seccomp/seccomp_unsafe.go
index be328db12..f7e986589 100644
--- a/pkg/seccomp/seccomp_unsafe.go
+++ b/pkg/seccomp/seccomp_unsafe.go
@@ -21,13 +21,6 @@ import (
 	"gvisor.dev/gvisor/pkg/abi/linux"
 )
 
-// sockFprog is sock_fprog taken from <linux/filter.h>.
-type sockFprog struct {
-	Len    uint16
-	pad    [6]byte
-	Filter *linux.BPFInstruction
-}
-
 // SetFilter installs the given BPF program.
 //
 // This is safe to call from an afterFork context.
@@ -39,7 +32,7 @@ func SetFilter(instrs []linux.BPFInstruction) syscall.Errno {
 		return errno
 	}
 
-	sockProg := sockFprog{
+	sockProg := linux.SockFprog{
 		Len:    uint16(len(instrs)),
 		Filter: (*linux.BPFInstruction)(unsafe.Pointer(&instrs[0])),
 	}
diff --git a/pkg/sentry/kernel/task_run.go b/pkg/sentry/kernel/task_run.go
index 2ba8d7e63..d654dd997 100644
--- a/pkg/sentry/kernel/task_run.go
+++ b/pkg/sentry/kernel/task_run.go
@@ -96,6 +96,7 @@ func (t *Task) run(threadID uintptr) {
 			t.tg.liveGoroutines.Done()
 			t.tg.pidns.owner.liveGoroutines.Done()
 			t.tg.pidns.owner.runningGoroutines.Done()
+			t.p.Release()
 
 			// Keep argument alive because stack trace for dead variables may not be correct.
 			runtime.KeepAlive(threadID)
diff --git a/pkg/sentry/platform/kvm/context.go b/pkg/sentry/platform/kvm/context.go
index c769ac7b4..6507121ea 100644
--- a/pkg/sentry/platform/kvm/context.go
+++ b/pkg/sentry/platform/kvm/context.go
@@ -85,3 +85,6 @@ func (c *context) Switch(as platform.AddressSpace, ac arch.Context, _ int32) (*a
 func (c *context) Interrupt() {
 	c.interrupt.NotifyInterrupt()
 }
+
+// Release implements platform.Context.Release().
+func (c *context) Release() {}
diff --git a/pkg/sentry/platform/kvm/kvm.go b/pkg/sentry/platform/kvm/kvm.go
index a9b4af43e..ae813e24e 100644
--- a/pkg/sentry/platform/kvm/kvm.go
+++ b/pkg/sentry/platform/kvm/kvm.go
@@ -191,6 +191,11 @@ func (*constructor) OpenDevice() (*os.File, error) {
 	return OpenDevice()
 }
 
+// Flags implements platform.Constructor.Flags().
+func (*constructor) Requirements() platform.Requirements {
+	return platform.Requirements{}
+}
+
 func init() {
 	platform.Register("kvm", &constructor{})
 }
diff --git a/pkg/sentry/platform/platform.go b/pkg/sentry/platform/platform.go
index 2ca696382..171513f3f 100644
--- a/pkg/sentry/platform/platform.go
+++ b/pkg/sentry/platform/platform.go
@@ -148,6 +148,9 @@ type Context interface {
 	// Interrupt interrupts a concurrent call to Switch(), causing it to return
 	// ErrContextInterrupt.
 	Interrupt()
+
+	// Release() releases any resources associated with this context.
+	Release()
 }
 
 var (
@@ -353,10 +356,28 @@ func (fr FileRange) String() string {
 	return fmt.Sprintf("[%#x, %#x)", fr.Start, fr.End)
 }
 
+// Requirements is used to specify platform specific requirements.
+type Requirements struct {
+	// RequiresCurrentPIDNS indicates that the sandbox has to be started in the
+	// current pid namespace.
+	RequiresCurrentPIDNS bool
+	// RequiresCapSysPtrace indicates that the sandbox has to be started with
+	// the CAP_SYS_PTRACE capability.
+	RequiresCapSysPtrace bool
+}
+
 // Constructor represents a platform type.
 type Constructor interface {
+	// New returns a new platform instance.
+	//
+	// Arguments:
+	//
+	// * deviceFile - the device file (e.g. /dev/kvm for the KVM platform).
 	New(deviceFile *os.File) (Platform, error)
 	OpenDevice() (*os.File, error)
+
+	// Requirements returns platform specific requirements.
+	Requirements() Requirements
 }
 
 // platforms contains all available platform types.
diff --git a/pkg/sentry/platform/ptrace/ptrace.go b/pkg/sentry/platform/ptrace/ptrace.go
index 03adb624b..08d055e05 100644
--- a/pkg/sentry/platform/ptrace/ptrace.go
+++ b/pkg/sentry/platform/ptrace/ptrace.go
@@ -177,6 +177,9 @@ func (c *context) Interrupt() {
 	c.interrupt.NotifyInterrupt()
 }
 
+// Release implements platform.Context.Release().
+func (c *context) Release() {}
+
 // PTrace represents a collection of ptrace subprocesses.
 type PTrace struct {
 	platform.MMapMinAddr
@@ -248,6 +251,16 @@ func (*constructor) OpenDevice() (*os.File, error) {
 	return nil, nil
 }
 
+// Flags implements platform.Constructor.Flags().
+func (*constructor) Requirements() platform.Requirements {
+	// TODO(b/75837838): Also set a new PID namespace so that we limit
+	// access to other host processes.
+	return platform.Requirements{
+		RequiresCapSysPtrace: true,
+		RequiresCurrentPIDNS: true,
+	}
+}
+
 func init() {
 	platform.Register("ptrace", &constructor{})
 }
diff --git a/pkg/sentry/platform/ptrace/subprocess.go b/pkg/sentry/platform/ptrace/subprocess.go
index a644609ef..773ddb1ed 100644
--- a/pkg/sentry/platform/ptrace/subprocess.go
+++ b/pkg/sentry/platform/ptrace/subprocess.go
@@ -332,7 +332,7 @@ func (t *thread) unexpectedStubExit() {
 	msg, err := t.getEventMessage()
 	status := syscall.WaitStatus(msg)
 	if status.Signaled() && status.Signal() == syscall.SIGKILL {
-		// SIGKILL can be only sent by an user or OOM-killer. In both
+		// SIGKILL can be only sent by a user or OOM-killer. In both
 		// these cases, we don't need to panic. There is no reasons to
 		// think that something wrong in gVisor.
 		log.Warningf("The ptrace stub process %v has been killed by SIGKILL.", t.tgid)