[netstack] Implement MSG_ERRQUEUE flag for recvmsg(2).

Introduces the per-socket error queue and the necessary cmsg mechanisms.

PiperOrigin-RevId: 348028508

2 files changed, 94 insertions, 0 deletions

diff --git a/pkg/abi/linux/BUILD b/pkg/abi/linux/BUILD
index a0654df2f..8fa61d6f7 100644
--- a/pkg/abi/linux/BUILD
+++ b/pkg/abi/linux/BUILD
@@ -21,6 +21,7 @@ go_library(
         "epoll_amd64.go",
         "epoll_arm64.go",
         "errors.go",
+        "errqueue.go",
         "eventfd.go",
         "exec.go",
         "fadvise.go",
diff --git a/pkg/abi/linux/errqueue.go b/pkg/abi/linux/errqueue.go
new file mode 100644
index 000000000..3905d4222
--- /dev/null
+++ b/pkg/abi/linux/errqueue.go
@@ -0,0 +1,93 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package linux
+
+import (
+	"gvisor.dev/gvisor/pkg/marshal"
+)
+
+// Socket error origin codes as defined in include/uapi/linux/errqueue.h.
+const (
+	SO_EE_ORIGIN_NONE  = 0
+	SO_EE_ORIGIN_LOCAL = 1
+	SO_EE_ORIGIN_ICMP  = 2
+	SO_EE_ORIGIN_ICMP6 = 3
+)
+
+// SockExtendedErr represents struct sock_extended_err in Linux defined in
+// include/uapi/linux/errqueue.h.
+//
+// +marshal
+type SockExtendedErr struct {
+	Errno  uint32
+	Origin uint8
+	Type   uint8
+	Code   uint8
+	Pad    uint8
+	Info   uint32
+	Data   uint32
+}
+
+// SockErrCMsg represents the IP*_RECVERR control message.
+type SockErrCMsg interface {
+	marshal.Marshallable
+
+	CMsgLevel() uint32
+	CMsgType() uint32
+}
+
+// SockErrCMsgIPv4 is the IP_RECVERR control message used in
+// recvmsg(MSG_ERRQUEUE) by ipv4 sockets. This is equilavent to `struct errhdr`
+// defined in net/ipv4/ip_sockglue.c:ip_recv_error().
+//
+// +marshal
+type SockErrCMsgIPv4 struct {
+	SockExtendedErr
+	Offender SockAddrInet
+}
+
+var _ SockErrCMsg = (*SockErrCMsgIPv4)(nil)
+
+// CMsgLevel implements SockErrCMsg.CMsgLevel.
+func (*SockErrCMsgIPv4) CMsgLevel() uint32 {
+	return SOL_IP
+}
+
+// CMsgType implements SockErrCMsg.CMsgType.
+func (*SockErrCMsgIPv4) CMsgType() uint32 {
+	return IP_RECVERR
+}
+
+// SockErrCMsgIPv6 is the IPV6_RECVERR control message used in
+// recvmsg(MSG_ERRQUEUE) by ipv6 sockets. This is equilavent to `struct errhdr`
+// defined in net/ipv6/datagram.c:ipv6_recv_error().
+//
+// +marshal
+type SockErrCMsgIPv6 struct {
+	SockExtendedErr
+	Offender SockAddrInet6
+}
+
+var _ SockErrCMsg = (*SockErrCMsgIPv6)(nil)
+
+// CMsgLevel implements SockErrCMsg.CMsgLevel.
+func (*SockErrCMsgIPv6) CMsgLevel() uint32 {
+	return SOL_IPV6
+}
+
+// CMsgType implements SockErrCMsg.CMsgType.
+func (*SockErrCMsgIPv6) CMsgType() uint32 {
+	return IPV6_RECVERR
+}