diff options
| author | Ghanan Gowripalan <ghanan@google.com> | 2021-08-19 13:51:40 -0700 |
|---|---|---|
| committer | gVisor bot <gvisor-bot@google.com> | 2021-08-19 13:54:53 -0700 |
| commit | 3b4bb947517d0d9010120aaa1c3989fd6abf278e (patch) | |
| tree | 73fd56f5f9ea152954f6e789231bcb76577e47de /runsc/boot | |
| parent | 50ed6b2e0994225b9bffa63b57a42da2d05e02b9 (diff) | |
Add loopback interface as an ethernet-based device
...to match Linux behaviour.
We can see evidence of Linux representing loopback as an ethernet-based
device below:
```
# EUI-48 based MAC addresses.
$ ip link show lo
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
# tcpdump showing ethernet frames when sniffing loopback and logging the
# link-type as EN10MB (Ethernet).
$ sudo tcpdump -i lo -e -c 2 -n
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on lo, link-type EN10MB (Ethernet), snapshot length 262144 bytes
03:09:05.002034 00:00:00:00:00:00 > 00:00:00:00:00:00, ethertype IPv4 (0x0800), length 66: 127.0.0.1.9557 > 127.0.0.1.36828: Flags [.], ack 3562800815, win 15342, options [nop,nop,TS val 843174495 ecr 843159493], length 0
03:09:05.002094 00:00:00:00:00:00 > 00:00:00:00:00:00, ethertype IPv4 (0x0800), length 66: 127.0.0.1.36828 > 127.0.0.1.9557: Flags [.], ack 1, win 6160, options [nop,nop,TS val 843174496 ecr 843159493], length 0
2 packets captured
116 packets received by filter
0 packets dropped by kernel
```
Wireshark shows a similar result as the tcpdump example above.
Linux's loopback setup: https://github.com/torvalds/linux/blob/5bfc75d92efd494db37f5c4c173d3639d4772966/drivers/net/loopback.c#L162
PiperOrigin-RevId: 391836719
Diffstat (limited to 'runsc/boot')
| -rw-r--r-- | runsc/boot/BUILD | 1 | ||||
| -rw-r--r-- | runsc/boot/loader.go | 3 | ||||
| -rw-r--r-- | runsc/boot/network.go | 3 |
3 files changed, 5 insertions, 2 deletions
diff --git a/runsc/boot/BUILD b/runsc/boot/BUILD index 1c57f9dd5..0ded907f0 100644 --- a/runsc/boot/BUILD +++ b/runsc/boot/BUILD @@ -97,6 +97,7 @@ go_library( "//pkg/sentry/watchdog", "//pkg/sync", "//pkg/tcpip", + "//pkg/tcpip/link/ethernet", "//pkg/tcpip/link/fdbased", "//pkg/tcpip/link/loopback", "//pkg/tcpip/link/packetsocket", diff --git a/runsc/boot/loader.go b/runsc/boot/loader.go index ec9188021..3f667cd74 100644 --- a/runsc/boot/loader.go +++ b/runsc/boot/loader.go @@ -58,6 +58,7 @@ import ( "gvisor.dev/gvisor/pkg/sentry/watchdog" "gvisor.dev/gvisor/pkg/sync" "gvisor.dev/gvisor/pkg/tcpip" + "gvisor.dev/gvisor/pkg/tcpip/link/ethernet" "gvisor.dev/gvisor/pkg/tcpip/link/loopback" "gvisor.dev/gvisor/pkg/tcpip/link/sniffer" "gvisor.dev/gvisor/pkg/tcpip/network/arp" @@ -1174,7 +1175,7 @@ func (f *sandboxNetstackCreator) CreateStack() (inet.Stack, error) { n := &Network{Stack: s.(*netstack.Stack).Stack} nicID := tcpip.NICID(f.uniqueID.UniqueID()) link := DefaultLoopbackLink - linkEP := loopback.New() + linkEP := ethernet.New(loopback.New()) if err := n.createNICWithAddrs(nicID, link.Name, linkEP, link.Addresses); err != nil { return nil, err } diff --git a/runsc/boot/network.go b/runsc/boot/network.go index 7e627e4c6..5c6879198 100644 --- a/runsc/boot/network.go +++ b/runsc/boot/network.go @@ -23,6 +23,7 @@ import ( "golang.org/x/sys/unix" "gvisor.dev/gvisor/pkg/log" "gvisor.dev/gvisor/pkg/tcpip" + "gvisor.dev/gvisor/pkg/tcpip/link/ethernet" "gvisor.dev/gvisor/pkg/tcpip/link/fdbased" "gvisor.dev/gvisor/pkg/tcpip/link/loopback" "gvisor.dev/gvisor/pkg/tcpip/link/packetsocket" @@ -169,7 +170,7 @@ func (n *Network) CreateLinksAndRoutes(args *CreateLinksAndRoutesArgs, _ *struct nicID++ nicids[link.Name] = nicID - linkEP := loopback.New() + linkEP := ethernet.New(loopback.New()) log.Infof("Enabling loopback interface %q with id %d on addresses %+v", link.Name, nicID, link.Addresses) if err := n.createNICWithAddrs(nicID, link.Name, linkEP, link.Addresses); err != nil { |