Avoid importing platforms from many source files

PiperOrigin-RevId: 256494243

8 files changed, 127 insertions, 0 deletions

diff --git a/pkg/sentry/platform/BUILD b/pkg/sentry/platform/BUILD
index 0b9962b2b..9aa6ec507 100644
--- a/pkg/sentry/platform/BUILD
+++ b/pkg/sentry/platform/BUILD
@@ -28,6 +28,7 @@ go_library(
         "//pkg/abi/linux",
         "//pkg/atomicbitops",
         "//pkg/log",
+        "//pkg/seccomp",
         "//pkg/sentry/arch",
         "//pkg/sentry/context",
         "//pkg/sentry/platform/safecopy",
diff --git a/pkg/sentry/platform/kvm/BUILD b/pkg/sentry/platform/kvm/BUILD
index 9ccf77fdf..ad8b95744 100644
--- a/pkg/sentry/platform/kvm/BUILD
+++ b/pkg/sentry/platform/kvm/BUILD
@@ -14,6 +14,7 @@ go_library(
         "bluepill_fault.go",
         "bluepill_unsafe.go",
         "context.go",
+        "filters.go",
         "kvm.go",
         "kvm_amd64.go",
         "kvm_amd64_unsafe.go",
@@ -33,6 +34,7 @@ go_library(
         "//pkg/cpuid",
         "//pkg/log",
         "//pkg/procid",
+        "//pkg/seccomp",
         "//pkg/sentry/arch",
         "//pkg/sentry/platform",
         "//pkg/sentry/platform/interrupt",
diff --git a/pkg/sentry/platform/kvm/filters.go b/pkg/sentry/platform/kvm/filters.go
new file mode 100644
index 000000000..7d949f1dd
--- /dev/null
+++ b/pkg/sentry/platform/kvm/filters.go
@@ -0,0 +1,33 @@
+// Copyright 2019 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 kvm
+
+import (
+	"syscall"
+
+	"gvisor.dev/gvisor/pkg/seccomp"
+)
+
+// SyscallFilters returns syscalls made exclusively by the KVM platform.
+func (*KVM) SyscallFilters() seccomp.SyscallRules {
+	return seccomp.SyscallRules{
+		syscall.SYS_ARCH_PRCTL:      {},
+		syscall.SYS_IOCTL:           {},
+		syscall.SYS_MMAP:            {},
+		syscall.SYS_RT_SIGSUSPEND:   {},
+		syscall.SYS_RT_SIGTIMEDWAIT: {},
+		0xffffffffffffffff:          {}, // KVM uses syscall -1 to transition to host.
+	}
+}
diff --git a/pkg/sentry/platform/kvm/kvm.go b/pkg/sentry/platform/kvm/kvm.go
index b49d7f3c4..ee4cd2f4d 100644
--- a/pkg/sentry/platform/kvm/kvm.go
+++ b/pkg/sentry/platform/kvm/kvm.go
@@ -141,3 +141,17 @@ func (k *KVM) NewContext() platform.Context {
 		machine: k.machine,
 	}
 }
+
+type constructor struct{}
+
+func (*constructor) New(f *os.File) (platform.Platform, error) {
+	return New(f)
+}
+
+func (*constructor) OpenDevice() (*os.File, error) {
+	return OpenDevice()
+}
+
+func init() {
+	platform.Register("kvm", &constructor{})
+}
diff --git a/pkg/sentry/platform/platform.go b/pkg/sentry/platform/platform.go
index eccbe2336..ec22dbf87 100644
--- a/pkg/sentry/platform/platform.go
+++ b/pkg/sentry/platform/platform.go
@@ -19,8 +19,10 @@ package platform
 
 import (
 	"fmt"
+	"os"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/seccomp"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
 	"gvisor.dev/gvisor/pkg/sentry/safemem"
 	"gvisor.dev/gvisor/pkg/sentry/usermem"
@@ -93,6 +95,9 @@ type Platform interface {
 	// Platforms for which this does not hold may panic if PreemptAllCPUs is
 	// called.
 	PreemptAllCPUs() error
+
+	// SyscallFilters returns syscalls made exclusively by this platform.
+	SyscallFilters() seccomp.SyscallRules
 }
 
 // NoCPUPreemptionDetection implements Platform.DetectsCPUPreemption and
@@ -347,3 +352,26 @@ type File interface {
 func (fr FileRange) String() string {
 	return fmt.Sprintf("[%#x, %#x)", fr.Start, fr.End)
 }
+
+// Constructor represents a platform type.
+type Constructor interface {
+	New(deviceFile *os.File) (Platform, error)
+	OpenDevice() (*os.File, error)
+}
+
+// platforms contains all available platform types.
+var platforms = map[string]Constructor{}
+
+// Register registers a new platform type.
+func Register(name string, platform Constructor) {
+	platforms[name] = platform
+}
+
+// Lookup looks up the platform constructor by name.
+func Lookup(name string) (Constructor, error) {
+	p, ok := platforms[name]
+	if !ok {
+		return nil, fmt.Errorf("unknown platform: %v", name)
+	}
+	return p, nil
+}
diff --git a/pkg/sentry/platform/ptrace/BUILD b/pkg/sentry/platform/ptrace/BUILD
index 6a1343f47..1b6c54e96 100644
--- a/pkg/sentry/platform/ptrace/BUILD
+++ b/pkg/sentry/platform/ptrace/BUILD
@@ -5,6 +5,7 @@ package(licenses = ["notice"])
 go_library(
     name = "ptrace",
     srcs = [
+        "filters.go",
         "ptrace.go",
         "ptrace_unsafe.go",
         "stub_amd64.s",
diff --git a/pkg/sentry/platform/ptrace/filters.go b/pkg/sentry/platform/ptrace/filters.go
new file mode 100644
index 000000000..1e07cfd0d
--- /dev/null
+++ b/pkg/sentry/platform/ptrace/filters.go
@@ -0,0 +1,33 @@
+// Copyright 2019 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 ptrace
+
+import (
+	"syscall"
+
+	"golang.org/x/sys/unix"
+	"gvisor.dev/gvisor/pkg/seccomp"
+)
+
+// SyscallFilters returns syscalls made exclusively by the ptrace platform.
+func (*PTrace) SyscallFilters() seccomp.SyscallRules {
+	return seccomp.SyscallRules{
+		unix.SYS_GETCPU:            {},
+		unix.SYS_SCHED_SETAFFINITY: {},
+		syscall.SYS_PTRACE:         {},
+		syscall.SYS_TGKILL:         {},
+		syscall.SYS_WAIT4:          {},
+	}
+}
diff --git a/pkg/sentry/platform/ptrace/ptrace.go b/pkg/sentry/platform/ptrace/ptrace.go
index ee7e0640c..6fd30ed25 100644
--- a/pkg/sentry/platform/ptrace/ptrace.go
+++ b/pkg/sentry/platform/ptrace/ptrace.go
@@ -45,6 +45,7 @@
 package ptrace
 
 import (
+	"os"
 	"sync"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
@@ -236,3 +237,17 @@ func (p *PTrace) NewAddressSpace(_ interface{}) (platform.AddressSpace, <-chan s
 func (*PTrace) NewContext() platform.Context {
 	return &context{}
 }
+
+type constructor struct{}
+
+func (*constructor) New(*os.File) (platform.Platform, error) {
+	return New()
+}
+
+func (*constructor) OpenDevice() (*os.File, error) {
+	return nil, nil
+}
+
+func init() {
+	platform.Register("ptrace", &constructor{})
+}