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Rpcinet is incorrectly handling MSG_TRUNC with SOCK_STREAM

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SOCK_STREAM has special behavior with respect to MSG_TRUNC. Specifically,
the data isn't actually copied back out to userspace when MSG_TRUNC is
provided on a SOCK_STREAM.

According to tcp(7): "Since version 2.4, Linux supports the use of
MSG_TRUNC in the flags argument of recv(2) (and recvmsg(2)). This flag
causes the received bytes of data to be discarded, rather than passed
back in a caller-supplied buffer."

PiperOrigin-RevId: 200134860
Change-Id: I70f17a5f60ffe7794c3f0cfafd131c069202e90d
This commit is contained in:
Brian Geffon
2018-06-11 16:40:38 -07:00
committed by Shentubot
parent 0412f17e06
commit ab2c2575d6
1 changed files with 14 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files
pkg/sentry/socket/rpcinet/socket.go
+14 -6
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@@ -465,9 +465,13 @@ func (s *socketOperations) RecvMsg(t *kernel.Task, dst usermem.IOSequence, flags
res, err := rpcRecvMsg(t, req)
if err == nil {
n, e := dst.CopyOut(t, res.Data)
if e == nil && n != len(res.Data) {
panic("CopyOut failed to copy full buffer")
var e error
var n int
if len(res.Data) > 0 {
n, e = dst.CopyOut(t, res.Data)
if e == nil && n != len(res.Data) {
panic("CopyOut failed to copy full buffer")
}
}
return int(res.Length), res.Address.GetAddress(), res.Address.GetLength(), socket.ControlMessages{}, syserr.FromError(e)
}
@@ -484,9 +488,13 @@ func (s *socketOperations) RecvMsg(t *kernel.Task, dst usermem.IOSequence, flags
for {
res, err := rpcRecvMsg(t, req)
if err == nil {
n, e := dst.CopyOut(t, res.Data)
if e == nil && n != len(res.Data) {
panic("CopyOut failed to copy full buffer")
var e error
var n int
if len(res.Data) > 0 {
n, e = dst.CopyOut(t, res.Data)
if e == nil && n != len(res.Data) {
panic("CopyOut failed to copy full buffer")
}
}
return int(res.Length), res.Address.GetAddress(), res.Address.GetLength(), socket.ControlMessages{}, syserr.FromError(e)
}