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Denote WithNetNS* functions with unsafe

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Please see https://github.com/weaveworks/weave/issues/2388#issuecomment-228365069
for more details.
This commit is contained in:
Martynas Pumputis committed 2016-07-05 15:12:39 +01:00
1 parent 7f5c37ef1e
commit 89221f117b
4 files changed
+26 -14
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common/utils.go
+3 -3
View File
@@ -48,7 +48,7 @@ func FindNetDevs(processID int, match func(link netlink.Link) bool) ([]NetDev, e
}
defer ns.Close()
err = weavenet.WithNetNS(ns, func() error {
err = weavenet.WithNetNSUnsafe(ns, func() error {
return forEachLink(func(link netlink.Link) error {
if match(link) {
netDev, err := linkToNetDev(link)
@@ -97,7 +97,7 @@ func linkToNetDev(link netlink.Link) (NetDev, error) {
func ConnectedToBridgePredicate(bridgeName string) (func(link netlink.Link) bool, error) {
var br netlink.Link
err := weavenet.WithNetNSLinkByPid(1, bridgeName, func(link netlink.Link) error {
err := weavenet.WithNetNSLinkByPidUnsafe(1, bridgeName, func(link netlink.Link) error {
br = link
return nil
})
@@ -160,7 +160,7 @@ func GetWeaveNetDevs(processID int) ([]NetDev, error) {
func GetBridgeNetDev(bridgeName string) (NetDev, error) {
var netdev NetDev
err := weavenet.WithNetNSLinkByPid(1, bridgeName, func(link netlink.Link) error {
err := weavenet.WithNetNSLinkByPidUnsafe(1, bridgeName, func(link netlink.Link) error {
var err error
netdev, err = linkToNetDev(link)
if err != nil {
net/netns.go
+17 -5
View File
@@ -7,7 +7,19 @@ import (
"github.com/vishvananda/netns"
)
func WithNetNS(ns netns.NsHandle, work func() error) error {
// NB: The following function is unsafe, because:
// - It changes a network namespace (netns) of an OS thread which runs
// the function. During execution, the Go runtime might clone a new OS thread
// for scheduling other go-routines, thus they might end up running in
// a "wrong" netns.
// - runtime.LockOSThread does not guarantee that a spawned go-routine on
// the locked thread will be run by it. Thus, the work function is
// not allowed to spawn any go-routine which is dependent on the given netns.
// Please see https://github.com/weaveworks/weave/issues/2388#issuecomment-228365069
// for more details and make sure that you understand the implications before
// using the function!
func WithNetNSUnsafe(ns netns.NsHandle, work func() error) error {
runtime.LockOSThread()
defer runtime.UnlockOSThread()
@@ -26,8 +38,8 @@ func WithNetNS(ns netns.NsHandle, work func() error) error {
return err
}
func WithNetNSLink(ns netns.NsHandle, ifName string, work func(link netlink.Link) error) error {
return WithNetNS(ns, func() error {
func WithNetNSLinkUnsafe(ns netns.NsHandle, ifName string, work func(link netlink.Link) error) error {
return WithNetNSUnsafe(ns, func() error {
link, err := netlink.LinkByName(ifName)
if err != nil {
return err
@@ -36,12 +48,12 @@ func WithNetNSLink(ns netns.NsHandle, ifName string, work func(link netlink.Link
})
}
func WithNetNSLinkByPid(pid int, ifName string, work func(link netlink.Link) error) error {
func WithNetNSLinkByPidUnsafe(pid int, ifName string, work func(link netlink.Link) error) error {
ns, err := netns.GetFromPid(pid)
if err != nil {
return err
}
defer ns.Close()
return WithNetNSLink(ns, ifName, work)
return WithNetNSLinkUnsafe(ns, ifName, work)
}
net/veth.go
+4 -4
View File
@@ -104,7 +104,7 @@ const (
)
func interfaceExistsInNamespace(ns netns.NsHandle, ifName string) bool {
err := WithNetNS(ns, func() error {
err := WithNetNSUnsafe(ns, func() error {
_, err := netlink.LinkByName(ifName)
return err
})
@@ -122,7 +122,7 @@ func AttachContainer(ns netns.NsHandle, id, ifName, bridgeName string, mtu int,
if err := netlink.LinkSetNsFd(veth, int(ns)); err != nil {
return fmt.Errorf("failed to move veth to container netns: %s", err)
}
if err := WithNetNS(ns, func() error {
if err := WithNetNSUnsafe(ns, func() error {
if err := netlink.LinkSetName(veth, ifName); err != nil {
return err
}
@@ -140,7 +140,7 @@ func AttachContainer(ns netns.NsHandle, id, ifName, bridgeName string, mtu int,
}
}
if err := WithNetNSLink(ns, ifName, func(veth netlink.Link) error {
if err := WithNetNSLinkUnsafe(ns, ifName, func(veth netlink.Link) error {
newAddresses, err := AddAddresses(veth, cidrs)
if err != nil {
return err
@@ -177,7 +177,7 @@ func AttachContainer(ns netns.NsHandle, id, ifName, bridgeName string, mtu int,
}
func DetachContainer(ns netns.NsHandle, id, ifName string, cidrs []*net.IPNet) error {
return WithNetNSLink(ns, ifName, func(veth netlink.Link) error {
return WithNetNSLinkUnsafe(ns, ifName, func(veth netlink.Link) error {
existingAddrs, err := netlink.AddrList(veth, netlink.FAMILY_V4)
if err != nil {
return fmt.Errorf("failed to get IP address for %q: %v", veth.Attrs().Name, err)
plugin/net/cni.go
+2 -2
View File
@@ -95,7 +95,7 @@ func (c *CNIPlugin) CmdAdd(args *skel.CmdArgs) error {
if err := weavenet.AttachContainer(ns, id, args.IfName, conf.BrName, conf.MTU, false, []*net.IPNet{&result.IP4.IP}, false); err != nil {
return err
}
if err := weavenet.WithNetNSLink(ns, args.IfName, func(link netlink.Link) error {
if err := weavenet.WithNetNSLinkUnsafe(ns, args.IfName, func(link netlink.Link) error {
return setupRoutes(link, args.IfName, result.IP4.IP, result.IP4.Gateway, result.IP4.Routes)
}); err != nil {
return fmt.Errorf("error setting up routes: %s", err)
@@ -158,7 +158,7 @@ func (c *CNIPlugin) CmdDel(args *skel.CmdArgs) error {
return err
}
defer ns.Close()
err = weavenet.WithNetNS(ns, func() error {
err = weavenet.WithNetNSUnsafe(ns, func() error {
link, err := netlink.LinkByName(args.IfName)
if err != nil {
return err