diff options
| -rw-r--r-- | pkg/sentry/socket/control/control.go | 51 | ||||
| -rw-r--r-- | pkg/sentry/socket/hostinet/socket.go | 18 | ||||
| -rw-r--r-- | pkg/sentry/syscalls/linux/sys_socket.go | 18 |
3 files changed, 50 insertions, 37 deletions
diff --git a/pkg/sentry/socket/control/control.go b/pkg/sentry/socket/control/control.go index fa3188d51..af1a4e95f 100644 --- a/pkg/sentry/socket/control/control.go +++ b/pkg/sentry/socket/control/control.go @@ -348,43 +348,62 @@ func PackTClass(t *kernel.Task, tClass int32, buf []byte) []byte { ) } -func addSpaceForCmsg(cmsgDataLen int, buf []byte) []byte { - newBuf := make([]byte, 0, len(buf)+linux.SizeOfControlMessageHeader+cmsgDataLen) - return append(newBuf, buf...) -} - -// PackControlMessages converts the given ControlMessages struct into a buffer. +// PackControlMessages packs control messages into the given buffer. +// // We skip control messages specific to Unix domain sockets. -func PackControlMessages(t *kernel.Task, cmsgs socket.ControlMessages) []byte { - var buf []byte - // The use of t.Arch().Width() is analogous to Linux's use of sizeof(long) in - // CMSG_ALIGN. - width := t.Arch().Width() - +// +// Note that some control messages may be truncated if they do not fit under +// the capacity of buf. +func PackControlMessages(t *kernel.Task, cmsgs socket.ControlMessages, buf []byte) []byte { if cmsgs.IP.HasTimestamp { - buf = addSpaceForCmsg(int(width), buf) buf = PackTimestamp(t, cmsgs.IP.Timestamp, buf) } if cmsgs.IP.HasInq { // In Linux, TCP_CM_INQ is added after SO_TIMESTAMP. - buf = addSpaceForCmsg(AlignUp(linux.SizeOfControlMessageInq, width), buf) buf = PackInq(t, cmsgs.IP.Inq, buf) } if cmsgs.IP.HasTOS { - buf = addSpaceForCmsg(AlignUp(linux.SizeOfControlMessageTOS, width), buf) buf = PackTOS(t, cmsgs.IP.TOS, buf) } if cmsgs.IP.HasTClass { - buf = addSpaceForCmsg(AlignUp(linux.SizeOfControlMessageTClass, width), buf) buf = PackTClass(t, cmsgs.IP.TClass, buf) } return buf } +// cmsgSpace is equivalent to CMSG_SPACE in Linux. +func cmsgSpace(t *kernel.Task, dataLen int) int { + return linux.SizeOfControlMessageHeader + AlignUp(dataLen, t.Arch().Width()) +} + +// CmsgsSpace returns the number of bytes needed to fit the control messages +// represented in cmsgs. +func CmsgsSpace(t *kernel.Task, cmsgs socket.ControlMessages) int { + space := 0 + + if cmsgs.IP.HasTimestamp { + space += cmsgSpace(t, linux.SizeOfTimeval) + } + + if cmsgs.IP.HasInq { + space += cmsgSpace(t, linux.SizeOfControlMessageInq) + } + + if cmsgs.IP.HasTOS { + space += cmsgSpace(t, linux.SizeOfControlMessageTOS) + } + + if cmsgs.IP.HasTClass { + space += cmsgSpace(t, linux.SizeOfControlMessageTClass) + } + + return space +} + // Parse parses a raw socket control message into portable objects. func Parse(t *kernel.Task, socketOrEndpoint interface{}, buf []byte) (socket.ControlMessages, error) { var ( diff --git a/pkg/sentry/socket/hostinet/socket.go b/pkg/sentry/socket/hostinet/socket.go index a8c152b54..c957b0f1d 100644 --- a/pkg/sentry/socket/hostinet/socket.go +++ b/pkg/sentry/socket/hostinet/socket.go @@ -45,7 +45,7 @@ const ( sizeofSockaddr = syscall.SizeofSockaddrInet6 // sizeof(sockaddr_in6) > sizeof(sockaddr_in) // maxControlLen is the maximum size of a control message buffer used in a - // recvmsg syscall. + // recvmsg or sendmsg syscall. maxControlLen = 1024 ) @@ -412,9 +412,12 @@ func (s *socketOperations) RecvMsg(t *kernel.Task, dst usermem.IOSequence, flags msg.Namelen = uint32(len(senderAddrBuf)) } if controlLen > 0 { - controlBuf = make([]byte, maxControlLen) + if controlLen > maxControlLen { + controlLen = maxControlLen + } + controlBuf = make([]byte, controlLen) msg.Control = &controlBuf[0] - msg.Controllen = maxControlLen + msg.Controllen = controlLen } n, err := recvmsg(s.fd, &msg, sysflags) if err != nil { @@ -489,7 +492,14 @@ func (s *socketOperations) SendMsg(t *kernel.Task, src usermem.IOSequence, to [] return 0, syserr.ErrInvalidArgument } - controlBuf := control.PackControlMessages(t, controlMessages) + space := uint64(control.CmsgsSpace(t, controlMessages)) + if space > maxControlLen { + space = maxControlLen + } + controlBuf := make([]byte, 0, space) + // PackControlMessages will append up to space bytes to controlBuf. + controlBuf = control.PackControlMessages(t, controlMessages, controlBuf) + sendmsgFromBlocks := safemem.WriterFunc(func(srcs safemem.BlockSeq) (uint64, error) { // Refuse to do anything if any part of src.Addrs was unusable. if uint64(src.NumBytes()) != srcs.NumBytes() { diff --git a/pkg/sentry/syscalls/linux/sys_socket.go b/pkg/sentry/syscalls/linux/sys_socket.go index e3faa890b..4b5aafcc0 100644 --- a/pkg/sentry/syscalls/linux/sys_socket.go +++ b/pkg/sentry/syscalls/linux/sys_socket.go @@ -787,29 +787,13 @@ func recvSingleMsg(t *kernel.Task, s socket.Socket, msgPtr usermem.Addr, flags i defer cms.Release() controlData := make([]byte, 0, msg.ControlLen) + controlData = control.PackControlMessages(t, cms, controlData) if cr, ok := s.(transport.Credentialer); ok && cr.Passcred() { creds, _ := cms.Unix.Credentials.(control.SCMCredentials) controlData, mflags = control.PackCredentials(t, creds, controlData, mflags) } - if cms.IP.HasTimestamp { - controlData = control.PackTimestamp(t, cms.IP.Timestamp, controlData) - } - - if cms.IP.HasInq { - // In Linux, TCP_CM_INQ is added after SO_TIMESTAMP. - controlData = control.PackInq(t, cms.IP.Inq, controlData) - } - - if cms.IP.HasTOS { - controlData = control.PackTOS(t, cms.IP.TOS, controlData) - } - - if cms.IP.HasTClass { - controlData = control.PackTClass(t, cms.IP.TClass, controlData) - } - if cms.Unix.Rights != nil { controlData, mflags = control.PackRights(t, cms.Unix.Rights.(control.SCMRights), flags&linux.MSG_CMSG_CLOEXEC != 0, controlData, mflags) } |