From 12235d533ae5c8b4b03c6d7f24cae785a2d6ec22 Mon Sep 17 00:00:00 2001
From: Kevin Krakauer <krakauer@google.com>
Date: Mon, 21 Oct 2019 13:21:58 -0700
Subject: AF_PACKET support for netstack (aka epsocket).
Like (AF_INET, SOCK_RAW) sockets, AF_PACKET sockets require CAP_NET_RAW. With
runsc, you'll need to pass `--net-raw=true` to enable them.
Binding isn't supported yet.
PiperOrigin-RevId: 275909366
---
pkg/sentry/socket/netstack/netstack.go | 40 +++++++++++++++++++++----
pkg/sentry/socket/netstack/provider.go | 53 ++++++++++++++++++++++++++++++++--
2 files changed, 86 insertions(+), 7 deletions(-)
(limited to 'pkg/sentry/socket')
diff --git a/pkg/sentry/socket/netstack/netstack.go b/pkg/sentry/socket/netstack/netstack.go
index 0ae573b45..debf9bce0 100644
--- a/pkg/sentry/socket/netstack/netstack.go
+++ b/pkg/sentry/socket/netstack/netstack.go
@@ -53,6 +53,7 @@ import (
"gvisor.dev/gvisor/pkg/syserror"
"gvisor.dev/gvisor/pkg/tcpip"
"gvisor.dev/gvisor/pkg/tcpip/buffer"
+ "gvisor.dev/gvisor/pkg/tcpip/header"
"gvisor.dev/gvisor/pkg/tcpip/stack"
"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
@@ -296,6 +297,7 @@ func New(t *kernel.Task, family int, skType linux.SockType, protocol int, queue
var sockAddrInetSize = int(binary.Size(linux.SockAddrInet{}))
var sockAddrInet6Size = int(binary.Size(linux.SockAddrInet6{}))
+var sockAddrLinkSize = int(binary.Size(linux.SockAddrLink{}))
// bytesToIPAddress converts an IPv4 or IPv6 address from the user to the
// netstack representation taking any addresses into account.
@@ -307,12 +309,12 @@ func bytesToIPAddress(addr []byte) tcpip.Address {
}
// AddressAndFamily reads an sockaddr struct from the given address and
-// converts it to the FullAddress format. It supports AF_UNIX, AF_INET and
-// AF_INET6 addresses.
+// converts it to the FullAddress format. It supports AF_UNIX, AF_INET,
+// AF_INET6, and AF_PACKET addresses.
//
// strict indicates whether addresses with the AF_UNSPEC family are accepted of not.
//
-// AddressAndFamily returns an address, its family.
+// AddressAndFamily returns an address and its family.
func AddressAndFamily(sfamily int, addr []byte, strict bool) (tcpip.FullAddress, uint16, *syserr.Error) {
// Make sure we have at least 2 bytes for the address family.
if len(addr) < 2 {
@@ -371,6 +373,22 @@ func AddressAndFamily(sfamily int, addr []byte, strict bool) (tcpip.FullAddress,
}
return out, family, nil
+ case linux.AF_PACKET:
+ var a linux.SockAddrLink
+ if len(addr) < sockAddrLinkSize {
+ return tcpip.FullAddress{}, family, syserr.ErrInvalidArgument
+ }
+ binary.Unmarshal(addr[:sockAddrLinkSize], usermem.ByteOrder, &a)
+ if a.Family != linux.AF_PACKET || a.HardwareAddrLen != header.EthernetAddressSize {
+ return tcpip.FullAddress{}, family, syserr.ErrInvalidArgument
+ }
+
+ // TODO(b/129292371): Return protocol too.
+ return tcpip.FullAddress{
+ NIC: tcpip.NICID(a.InterfaceIndex),
+ Addr: tcpip.Address(a.HardwareAddr[:header.EthernetAddressSize]),
+ }, family, nil
+
case linux.AF_UNSPEC:
return tcpip.FullAddress{}, family, nil
@@ -1951,12 +1969,14 @@ func ConvertAddress(family int, addr tcpip.FullAddress) (linux.SockAddr, uint32)
return &out, uint32(2 + l)
}
return &out, uint32(3 + l)
+
case linux.AF_INET:
var out linux.SockAddrInet
copy(out.Addr[:], addr.Addr)
out.Family = linux.AF_INET
out.Port = htons(addr.Port)
- return &out, uint32(binary.Size(out))
+ return &out, uint32(sockAddrInetSize)
+
case linux.AF_INET6:
var out linux.SockAddrInet6
if len(addr.Addr) == 4 {
@@ -1972,7 +1992,17 @@ func ConvertAddress(family int, addr tcpip.FullAddress) (linux.SockAddr, uint32)
if isLinkLocal(addr.Addr) {
out.Scope_id = uint32(addr.NIC)
}
- return &out, uint32(binary.Size(out))
+ return &out, uint32(sockAddrInet6Size)
+
+ case linux.AF_PACKET:
+ // TODO(b/129292371): Return protocol too.
+ var out linux.SockAddrLink
+ out.Family = linux.AF_PACKET
+ out.InterfaceIndex = int32(addr.NIC)
+ out.HardwareAddrLen = header.EthernetAddressSize
+ copy(out.HardwareAddr[:], addr.Addr)
+ return &out, uint32(sockAddrLinkSize)
+
default:
return nil, 0
}
diff --git a/pkg/sentry/socket/netstack/provider.go b/pkg/sentry/socket/netstack/provider.go
index 357a664cc..2d2c1ba2a 100644
--- a/pkg/sentry/socket/netstack/provider.go
+++ b/pkg/sentry/socket/netstack/provider.go
@@ -62,6 +62,10 @@ func getTransportProtocol(ctx context.Context, stype linux.SockType, protocol in
}
case linux.SOCK_RAW:
+ // TODO(b/142504697): "In order to create a raw socket, a
+ // process must have the CAP_NET_RAW capability in the user
+ // namespace that governs its network namespace." - raw(7)
+
// Raw sockets require CAP_NET_RAW.
creds := auth.CredentialsFromContext(ctx)
if !creds.HasCapability(linux.CAP_NET_RAW) {
@@ -85,7 +89,8 @@ func getTransportProtocol(ctx context.Context, stype linux.SockType, protocol in
return 0, true, syserr.ErrProtocolNotSupported
}
-// Socket creates a new socket object for the AF_INET or AF_INET6 family.
+// Socket creates a new socket object for the AF_INET, AF_INET6, or AF_PACKET
+// family.
func (p *provider) Socket(t *kernel.Task, stype linux.SockType, protocol int) (*fs.File, *syserr.Error) {
// Fail right away if we don't have a stack.
stack := t.NetworkContext()
@@ -99,6 +104,12 @@ func (p *provider) Socket(t *kernel.Task, stype linux.SockType, protocol int) (*
return nil, nil
}
+ // Packet sockets are handled separately, since they are neither INET
+ // nor INET6 specific.
+ if p.family == linux.AF_PACKET {
+ return packetSocket(t, eps, stype, protocol)
+ }
+
// Figure out the transport protocol.
transProto, associated, err := getTransportProtocol(t, stype, protocol)
if err != nil {
@@ -121,12 +132,47 @@ func (p *provider) Socket(t *kernel.Task, stype linux.SockType, protocol int) (*
return New(t, p.family, stype, int(transProto), wq, ep)
}
+func packetSocket(t *kernel.Task, epStack *Stack, stype linux.SockType, protocol int) (*fs.File, *syserr.Error) {
+ // TODO(b/142504697): "In order to create a packet socket, a process
+ // must have the CAP_NET_RAW capability in the user namespace that
+ // governs its network namespace." - packet(7)
+
+ // Packet sockets require CAP_NET_RAW.
+ creds := auth.CredentialsFromContext(t)
+ if !creds.HasCapability(linux.CAP_NET_RAW) {
+ return nil, syserr.ErrNotPermitted
+ }
+
+ // "cooked" packets don't contain link layer information.
+ var cooked bool
+ switch stype {
+ case linux.SOCK_DGRAM:
+ cooked = true
+ case linux.SOCK_RAW:
+ cooked = false
+ default:
+ return nil, syserr.ErrProtocolNotSupported
+ }
+
+ // protocol is passed in network byte order, but netstack wants it in
+ // host order.
+ netProto := tcpip.NetworkProtocolNumber(ntohs(uint16(protocol)))
+
+ wq := &waiter.Queue{}
+ ep, err := epStack.Stack.NewPacketEndpoint(cooked, netProto, wq)
+ if err != nil {
+ return nil, syserr.TranslateNetstackError(err)
+ }
+
+ return New(t, linux.AF_PACKET, stype, protocol, wq, ep)
+}
+
// Pair just returns nil sockets (not supported).
func (*provider) Pair(*kernel.Task, linux.SockType, int) (*fs.File, *fs.File, *syserr.Error) {
return nil, nil, nil
}
-// init registers socket providers for AF_INET and AF_INET6.
+// init registers socket providers for AF_INET, AF_INET6, and AF_PACKET.
func init() {
// Providers backed by netstack.
p := []provider{
@@ -138,6 +184,9 @@ func init() {
family: linux.AF_INET6,
netProto: ipv6.ProtocolNumber,
},
+ {
+ family: linux.AF_PACKET,
+ },
}
for i := range p {
--
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