diff options
| -rw-r--r-- | pkg/sentry/socket/hostinet/socket.go | 110 |
1 files changed, 62 insertions, 48 deletions
diff --git a/pkg/sentry/socket/hostinet/socket.go b/pkg/sentry/socket/hostinet/socket.go index be418df2e..1f220c343 100644 --- a/pkg/sentry/socket/hostinet/socket.go +++ b/pkg/sentry/socket/hostinet/socket.go @@ -416,6 +416,37 @@ func (s *socketOpsCommon) SetSockOpt(t *kernel.Task, level int, name int, opt [] return nil } +func (s *socketOpsCommon) recvMsgFromHost(iovs []syscall.Iovec, flags int, senderRequested bool, controlLen uint64) (uint64, int, []byte, []byte, error) { + // We always do a non-blocking recv*(). + sysflags := flags | syscall.MSG_DONTWAIT + + msg := syscall.Msghdr{} + if len(iovs) > 0 { + msg.Iov = &iovs[0] + msg.Iovlen = uint64(len(iovs)) + } + var senderAddrBuf []byte + if senderRequested { + senderAddrBuf = make([]byte, sizeofSockaddr) + msg.Name = &senderAddrBuf[0] + msg.Namelen = uint32(sizeofSockaddr) + } + var controlBuf []byte + if controlLen > 0 { + if controlLen > maxControlLen { + controlLen = maxControlLen + } + controlBuf = make([]byte, controlLen) + msg.Control = &controlBuf[0] + msg.Controllen = controlLen + } + n, err := recvmsg(s.fd, &msg, sysflags) + if err != nil { + return 0 /* n */, 0 /* mFlags */, nil /* senderAddrBuf */, nil /* controlBuf */, err + } + return n, int(msg.Flags), senderAddrBuf[:msg.Namelen], controlBuf[:msg.Controllen], err +} + // RecvMsg implements socket.Socket.RecvMsg. func (s *socketOpsCommon) RecvMsg(t *kernel.Task, dst usermem.IOSequence, flags int, haveDeadline bool, deadline ktime.Time, senderRequested bool, controlLen uint64) (int, int, linux.SockAddr, uint32, socket.ControlMessages, *syserr.Error) { // Only allow known and safe flags. @@ -427,56 +458,36 @@ func (s *socketOpsCommon) RecvMsg(t *kernel.Task, dst usermem.IOSequence, flags return 0, 0, nil, 0, socket.ControlMessages{}, syserr.ErrInvalidArgument } - var senderAddr linux.SockAddr var senderAddrBuf []byte - if senderRequested { - senderAddrBuf = make([]byte, sizeofSockaddr) - } - var controlBuf []byte var msgFlags int - - recvmsgToBlocks := safemem.ReaderFunc(func(dsts safemem.BlockSeq) (uint64, error) { - // Refuse to do anything if any part of dst.Addrs was unusable. - if uint64(dst.NumBytes()) != dsts.NumBytes() { - return 0, nil - } - if dsts.IsEmpty() { - return 0, nil - } - - // We always do a non-blocking recv*(). - sysflags := flags | syscall.MSG_DONTWAIT - - iovs := safemem.IovecsFromBlockSeq(dsts) - msg := syscall.Msghdr{ - Iov: &iovs[0], - Iovlen: uint64(len(iovs)), - } - if len(senderAddrBuf) != 0 { - msg.Name = &senderAddrBuf[0] - msg.Namelen = uint32(len(senderAddrBuf)) - } - if controlLen > 0 { - if controlLen > maxControlLen { - controlLen = maxControlLen + copyToDst := func() (int64, error) { + var n uint64 + var err error + if dst.NumBytes() == 0 { + // We want to make the recvmsg(2) call to the host even if dst is empty + // to fetch control messages, sender address or errors if any occur. + n, msgFlags, senderAddrBuf, controlBuf, err = s.recvMsgFromHost(nil, flags, senderRequested, controlLen) + return int64(n), err + } + + recvmsgToBlocks := safemem.ReaderFunc(func(dsts safemem.BlockSeq) (uint64, error) { + // Refuse to do anything if any part of dst.Addrs was unusable. + if uint64(dst.NumBytes()) != dsts.NumBytes() { + return 0, nil + } + if dsts.IsEmpty() { + return 0, nil } - controlBuf = make([]byte, controlLen) - msg.Control = &controlBuf[0] - msg.Controllen = controlLen - } - n, err := recvmsg(s.fd, &msg, sysflags) - if err != nil { - return 0, err - } - senderAddrBuf = senderAddrBuf[:msg.Namelen] - msgFlags = int(msg.Flags) - controlLen = uint64(msg.Controllen) - return n, nil - }) + + n, msgFlags, senderAddrBuf, controlBuf, err = s.recvMsgFromHost(safemem.IovecsFromBlockSeq(dsts), flags, senderRequested, controlLen) + return n, err + }) + return dst.CopyOutFrom(t, recvmsgToBlocks) + } var ch chan struct{} - n, err := dst.CopyOutFrom(t, recvmsgToBlocks) + n, err := copyToDst() if flags&syscall.MSG_DONTWAIT == 0 { for err == syserror.ErrWouldBlock { // We only expect blocking to come from the actual syscall, in which @@ -494,22 +505,26 @@ func (s *socketOpsCommon) RecvMsg(t *kernel.Task, dst usermem.IOSequence, flags s.EventRegister(&e, waiter.EventIn) defer s.EventUnregister(&e) } - n, err = dst.CopyOutFrom(t, recvmsgToBlocks) + n, err = copyToDst() } } if err != nil { return 0, 0, nil, 0, socket.ControlMessages{}, syserr.FromError(err) } + var senderAddr linux.SockAddr if senderRequested { senderAddr = socket.UnmarshalSockAddr(s.family, senderAddrBuf) } - unixControlMessages, err := unix.ParseSocketControlMessage(controlBuf[:controlLen]) + unixControlMessages, err := unix.ParseSocketControlMessage(controlBuf) if err != nil { return 0, 0, nil, 0, socket.ControlMessages{}, syserr.FromError(err) } + return int(n), msgFlags, senderAddr, uint32(len(senderAddrBuf)), parseUnixControlMessages(unixControlMessages), nil +} +func parseUnixControlMessages(unixControlMessages []unix.SocketControlMessage) socket.ControlMessages { controlMessages := socket.ControlMessages{} for _, unixCmsg := range unixControlMessages { switch unixCmsg.Header.Level { @@ -558,8 +573,7 @@ func (s *socketOpsCommon) RecvMsg(t *kernel.Task, dst usermem.IOSequence, flags } } } - - return int(n), msgFlags, senderAddr, uint32(len(senderAddrBuf)), controlMessages, nil + return controlMessages } // SendMsg implements socket.Socket.SendMsg. |