Check in gVisor.

PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

2 files changed, 184 insertions, 0 deletions

diff --git a/pkg/sentry/socket/rpcinet/conn/BUILD b/pkg/sentry/socket/rpcinet/conn/BUILD
new file mode 100644
index 000000000..4923dee4b
--- /dev/null
+++ b/pkg/sentry/socket/rpcinet/conn/BUILD
@@ -0,0 +1,17 @@
+package(licenses = ["notice"])  # BSD
+
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "conn",
+    srcs = ["conn.go"],
+    importpath = "gvisor.googlesource.com/gvisor/pkg/sentry/socket/rpcinet/conn",
+    visibility = ["//pkg/sentry:internal"],
+    deps = [
+        "//pkg/binary",
+        "//pkg/sentry/socket/rpcinet:syscall_rpc_go_proto",
+        "//pkg/syserr",
+        "//pkg/unet",
+        "@com_github_golang_protobuf//proto:go_default_library",
+    ],
+)
diff --git a/pkg/sentry/socket/rpcinet/conn/conn.go b/pkg/sentry/socket/rpcinet/conn/conn.go
new file mode 100644
index 000000000..ea6ec87ed
--- /dev/null
+++ b/pkg/sentry/socket/rpcinet/conn/conn.go
@@ -0,0 +1,167 @@
+// 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 conn is an RPC connection to a syscall RPC server.
+package conn
+
+import (
+	"fmt"
+	"sync"
+	"sync/atomic"
+	"syscall"
+
+	"github.com/golang/protobuf/proto"
+	"gvisor.googlesource.com/gvisor/pkg/binary"
+	"gvisor.googlesource.com/gvisor/pkg/syserr"
+	"gvisor.googlesource.com/gvisor/pkg/unet"
+
+	pb "gvisor.googlesource.com/gvisor/pkg/sentry/socket/rpcinet/syscall_rpc_go_proto"
+)
+
+type request struct {
+	response     []byte
+	ready        chan struct{}
+	ignoreResult bool
+}
+
+// RPCConnection represents a single RPC connection to a syscall gofer.
+type RPCConnection struct {
+	// reqID is the ID of the last request and must be accessed atomically.
+	reqID uint64
+
+	sendMu sync.Mutex
+	socket *unet.Socket
+
+	reqMu    sync.Mutex
+	requests map[uint64]request
+}
+
+// NewRPCConnection initializes a RPC connection to a socket gofer.
+func NewRPCConnection(s *unet.Socket) *RPCConnection {
+	conn := &RPCConnection{socket: s, requests: map[uint64]request{}}
+	go func() { // S/R-FIXME
+		var nums [16]byte
+		for {
+			for n := 0; n < len(nums); {
+				nn, err := conn.socket.Read(nums[n:])
+				if err != nil {
+					panic(fmt.Sprint("error reading length from socket rpc gofer: ", err))
+				}
+				n += nn
+			}
+
+			b := make([]byte, binary.LittleEndian.Uint64(nums[:8]))
+			id := binary.LittleEndian.Uint64(nums[8:])
+
+			for n := 0; n < len(b); {
+				nn, err := conn.socket.Read(b[n:])
+				if err != nil {
+					panic(fmt.Sprint("error reading request from socket rpc gofer: ", err))
+				}
+				n += nn
+			}
+
+			conn.reqMu.Lock()
+			r := conn.requests[id]
+			if r.ignoreResult {
+				delete(conn.requests, id)
+			} else {
+				r.response = b
+				conn.requests[id] = r
+			}
+			conn.reqMu.Unlock()
+			close(r.ready)
+		}
+	}()
+	return conn
+}
+
+// NewRequest makes a request to the RPC gofer and returns the request ID and a
+// channel which will be closed once the request completes.
+func (c *RPCConnection) NewRequest(req pb.SyscallRequest, ignoreResult bool) (uint64, chan struct{}) {
+	b, err := proto.Marshal(&req)
+	if err != nil {
+		panic(fmt.Sprint("invalid proto: ", err))
+	}
+
+	id := atomic.AddUint64(&c.reqID, 1)
+	ch := make(chan struct{})
+
+	c.reqMu.Lock()
+	c.requests[id] = request{ready: ch, ignoreResult: ignoreResult}
+	c.reqMu.Unlock()
+
+	c.sendMu.Lock()
+	defer c.sendMu.Unlock()
+
+	var nums [16]byte
+	binary.LittleEndian.PutUint64(nums[:8], uint64(len(b)))
+	binary.LittleEndian.PutUint64(nums[8:], id)
+	for n := 0; n < len(nums); {
+		nn, err := c.socket.Write(nums[n:])
+		if err != nil {
+			panic(fmt.Sprint("error writing length and ID to socket gofer: ", err))
+		}
+		n += nn
+	}
+
+	for n := 0; n < len(b); {
+		nn, err := c.socket.Write(b[n:])
+		if err != nil {
+			panic(fmt.Sprint("error writing request to socket gofer: ", err))
+		}
+		n += nn
+	}
+
+	return id, ch
+}
+
+// RPCReadFile will execute the ReadFile helper RPC method which avoids the
+// common pattern of open(2), read(2), close(2) by doing all three operations
+// as a single RPC. It will read the entire file or return EFBIG if the file
+// was too large.
+func (c *RPCConnection) RPCReadFile(path string) ([]byte, *syserr.Error) {
+	req := &pb.SyscallRequest_ReadFile{&pb.ReadFileRequest{
+		Path: path,
+	}}
+
+	id, ch := c.NewRequest(pb.SyscallRequest{Args: req}, false /* ignoreResult */)
+	<-ch
+
+	res := c.Request(id).Result.(*pb.SyscallResponse_ReadFile).ReadFile.Result
+	if e, ok := res.(*pb.ReadFileResponse_ErrorNumber); ok {
+		return nil, syserr.FromHost(syscall.Errno(e.ErrorNumber))
+	}
+
+	return res.(*pb.ReadFileResponse_Data).Data, nil
+}
+
+// Request retrieves the request corresponding to the given request ID.
+//
+// The channel returned by NewRequest must have been closed before Request can
+// be called. This will happen automatically, do not manually close the
+// channel.
+func (c *RPCConnection) Request(id uint64) pb.SyscallResponse {
+	c.reqMu.Lock()
+	r := c.requests[id]
+	delete(c.requests, id)
+	c.reqMu.Unlock()
+
+	var resp pb.SyscallResponse
+	if err := proto.Unmarshal(r.response, &resp); err != nil {
+		panic(fmt.Sprint("invalid proto: ", err))
+	}
+
+	return resp
+}