From 7bfad8ebb6ce71c0fe90a1e4f5897f62809fa58b Mon Sep 17 00:00:00 2001
From: Rahat Mahmood <rahat@google.com>
Date: Thu, 8 Aug 2019 16:49:18 -0700
Subject: Return a well-defined socket address type from socket funtions.

Previously we were representing socket addresses as an interface{},
which allowed any type which could be binary.Marshal()ed to be used as
a socket address. This is fine when the address is passed to userspace
via the linux ABI, but is problematic when used from within the sentry
such as by networking procfs files.

PiperOrigin-RevId: 262460640
---
 pkg/sentry/socket/hostinet/socket.go | 35 ++++++++++++++++++++---------------
 1 file changed, 20 insertions(+), 15 deletions(-)

(limited to 'pkg/sentry/socket/hostinet/socket.go')

diff --git a/pkg/sentry/socket/hostinet/socket.go b/pkg/sentry/socket/hostinet/socket.go
index 618ea42c7..92beb1bcf 100644
--- a/pkg/sentry/socket/hostinet/socket.go
+++ b/pkg/sentry/socket/hostinet/socket.go
@@ -189,15 +189,16 @@ func (s *socketOperations) Connect(t *kernel.Task, sockaddr []byte, blocking boo
 }
 
 // Accept implements socket.Socket.Accept.
-func (s *socketOperations) Accept(t *kernel.Task, peerRequested bool, flags int, blocking bool) (int32, interface{}, uint32, *syserr.Error) {
-	var peerAddr []byte
+func (s *socketOperations) Accept(t *kernel.Task, peerRequested bool, flags int, blocking bool) (int32, linux.SockAddr, uint32, *syserr.Error) {
+	var peerAddr linux.SockAddr
+	var peerAddrBuf []byte
 	var peerAddrlen uint32
 	var peerAddrPtr *byte
 	var peerAddrlenPtr *uint32
 	if peerRequested {
-		peerAddr = make([]byte, sizeofSockaddr)
-		peerAddrlen = uint32(len(peerAddr))
-		peerAddrPtr = &peerAddr[0]
+		peerAddrBuf = make([]byte, sizeofSockaddr)
+		peerAddrlen = uint32(len(peerAddrBuf))
+		peerAddrPtr = &peerAddrBuf[0]
 		peerAddrlenPtr = &peerAddrlen
 	}
 
@@ -222,7 +223,7 @@ func (s *socketOperations) Accept(t *kernel.Task, peerRequested bool, flags int,
 	}
 
 	if peerRequested {
-		peerAddr = peerAddr[:peerAddrlen]
+		peerAddr = socket.UnmarshalSockAddr(s.family, peerAddrBuf[:peerAddrlen])
 	}
 	if syscallErr != nil {
 		return 0, peerAddr, peerAddrlen, syserr.FromError(syscallErr)
@@ -353,7 +354,7 @@ func (s *socketOperations) SetSockOpt(t *kernel.Task, level int, name int, opt [
 }
 
 // RecvMsg implements socket.Socket.RecvMsg.
-func (s *socketOperations) RecvMsg(t *kernel.Task, dst usermem.IOSequence, flags int, haveDeadline bool, deadline ktime.Time, senderRequested bool, controlDataLen uint64) (int, int, interface{}, uint32, socket.ControlMessages, *syserr.Error) {
+func (s *socketOperations) RecvMsg(t *kernel.Task, dst usermem.IOSequence, flags int, haveDeadline bool, deadline ktime.Time, senderRequested bool, controlDataLen uint64) (int, int, linux.SockAddr, uint32, socket.ControlMessages, *syserr.Error) {
 	// Whitelist flags.
 	//
 	// FIXME(jamieliu): We can't support MSG_ERRQUEUE because it uses ancillary
@@ -363,9 +364,10 @@ func (s *socketOperations) RecvMsg(t *kernel.Task, dst usermem.IOSequence, flags
 		return 0, 0, nil, 0, socket.ControlMessages{}, syserr.ErrInvalidArgument
 	}
 
-	var senderAddr []byte
+	var senderAddr linux.SockAddr
+	var senderAddrBuf []byte
 	if senderRequested {
-		senderAddr = make([]byte, sizeofSockaddr)
+		senderAddrBuf = make([]byte, sizeofSockaddr)
 	}
 
 	var msgFlags int
@@ -384,7 +386,7 @@ func (s *socketOperations) RecvMsg(t *kernel.Task, dst usermem.IOSequence, flags
 
 		if dsts.NumBlocks() == 1 {
 			// Skip allocating []syscall.Iovec.
-			return recvfrom(s.fd, dsts.Head().ToSlice(), sysflags, &senderAddr)
+			return recvfrom(s.fd, dsts.Head().ToSlice(), sysflags, &senderAddrBuf)
 		}
 
 		iovs := iovecsFromBlockSeq(dsts)
@@ -392,15 +394,15 @@ func (s *socketOperations) RecvMsg(t *kernel.Task, dst usermem.IOSequence, flags
 			Iov:    &iovs[0],
 			Iovlen: uint64(len(iovs)),
 		}
-		if len(senderAddr) != 0 {
-			msg.Name = &senderAddr[0]
-			msg.Namelen = uint32(len(senderAddr))
+		if len(senderAddrBuf) != 0 {
+			msg.Name = &senderAddrBuf[0]
+			msg.Namelen = uint32(len(senderAddrBuf))
 		}
 		n, err := recvmsg(s.fd, &msg, sysflags)
 		if err != nil {
 			return 0, err
 		}
-		senderAddr = senderAddr[:msg.Namelen]
+		senderAddrBuf = senderAddrBuf[:msg.Namelen]
 		msgFlags = int(msg.Flags)
 		return n, nil
 	})
@@ -431,7 +433,10 @@ func (s *socketOperations) RecvMsg(t *kernel.Task, dst usermem.IOSequence, flags
 	// We don't allow control messages.
 	msgFlags &^= linux.MSG_CTRUNC
 
-	return int(n), msgFlags, senderAddr, uint32(len(senderAddr)), socket.ControlMessages{}, syserr.FromError(err)
+	if senderRequested {
+		senderAddr = socket.UnmarshalSockAddr(s.family, senderAddrBuf)
+	}
+	return int(n), msgFlags, senderAddr, uint32(len(senderAddrBuf)), socket.ControlMessages{}, syserr.FromError(err)
 }
 
 // SendMsg implements socket.Socket.SendMsg.
-- 
cgit v1.2.3