From ba828233b9e934992ac024232e5018ce9971f334 Mon Sep 17 00:00:00 2001
From: Ian Gudger <igudger@google.com>
Date: Thu, 21 Mar 2019 13:18:00 -0700
Subject: Clear msghdr flags on successful recvmsg.
.net sets these flags to -1 and then uses their result, especting it to be
zero.
Does not set actual flags (e.g. MSG_TRUNC), but setting to zero is more correct
than what we did before.
PiperOrigin-RevId: 239657951
Change-Id: I89c5f84bc9b94a2cd8ff84e8ecfea09e01142030
---
pkg/sentry/syscalls/linux/sys_socket.go | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
(limited to 'pkg/sentry')
diff --git a/pkg/sentry/syscalls/linux/sys_socket.go b/pkg/sentry/syscalls/linux/sys_socket.go
index 1513f28e7..564357bac 100644
--- a/pkg/sentry/syscalls/linux/sys_socket.go
+++ b/pkg/sentry/syscalls/linux/sys_socket.go
@@ -57,6 +57,10 @@ const nameLenOffset = 8
// to the ControlLen field.
const controlLenOffset = 40
+// flagsOffset is the offset form the start of the MessageHeader64 struct
+// to the Flags field.
+const flagsOffset = 48
+
// messageHeader64Len is the length of a MessageHeader64 struct.
var messageHeader64Len = uint64(binary.Size(MessageHeader64{}))
@@ -743,6 +747,16 @@ func recvSingleMsg(t *kernel.Task, s socket.Socket, msgPtr usermem.Addr, flags i
return 0, syserror.ConvertIntr(err.ToError(), kernel.ERESTARTSYS)
}
cms.Unix.Release()
+
+ if msg.Flags != 0 {
+ // Copy out the flags to the caller.
+ //
+ // TODO: Plumb through actual flags.
+ if _, err := t.CopyOut(msgPtr+flagsOffset, int32(0)); err != nil {
+ return 0, err
+ }
+ }
+
return uintptr(n), nil
}
@@ -787,6 +801,13 @@ func recvSingleMsg(t *kernel.Task, s socket.Socket, msgPtr usermem.Addr, flags i
}
}
+ // Copy out the flags to the caller.
+ //
+ // TODO: Plumb through actual flags.
+ if _, err := t.CopyOut(msgPtr+flagsOffset, int32(0)); err != nil {
+ return 0, err
+ }
+
return uintptr(n), nil
}
--
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