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specgen: improve heuristic for /sys bind mount #8949

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merged 1 commit into from
Jan 15, 2021
+29 −18
Merged

specgen: improve heuristic for /sys bind mount #8949

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39 changes: 21 additions & 18 deletions pkg/specgen/generate/oci.go
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Original file line number Diff line number Diff line change
Expand Up @@ -138,10 +138,23 @@ func makeCommand(ctx context.Context, s *specgen.SpecGenerator, img *image.Image
return finalCommand, nil
}

// canMountSys is a best-effort heuristic to detect whether mounting a new sysfs is permitted in the container
func canMountSys(isRootless, isNewUserns bool, s *specgen.SpecGenerator) bool {
if s.NetNS.IsHost() && (isRootless || isNewUserns) {
return false
}
if isNewUserns {
switch s.NetNS.NSMode {
case specgen.Slirp, specgen.Private, specgen.NoNetwork, specgen.Bridge:
return true
default:
return false
}
}
return true
}

func SpecGenToOCI(ctx context.Context, s *specgen.SpecGenerator, rt *libpod.Runtime, rtc *config.Config, newImage *image.Image, mounts []spec.Mount, pod *libpod.Pod, finalCmd []string) (*spec.Spec, error) {
var (
inUserNS bool
)
cgroupPerm := "ro"
g, err := generate.New("linux")
if err != nil {
Expand All @@ -151,23 +164,11 @@ func SpecGenToOCI(ctx context.Context, s *specgen.SpecGenerator, rt *libpod.Runt
g.RemoveMount("/dev/shm")
g.HostSpecific = true
addCgroup := true
canMountSys := true

isRootless := rootless.IsRootless()
if isRootless {
inUserNS = true
}
if !s.UserNS.IsHost() {
if s.UserNS.IsContainer() || s.UserNS.IsPath() {
inUserNS = true
}
if s.UserNS.IsPrivate() {
inUserNS = true
}
}
if inUserNS && s.NetNS.NSMode != specgen.NoNetwork {
canMountSys = false
}
isNewUserns := s.UserNS.IsContainer() || s.UserNS.IsPath() || s.UserNS.IsPrivate()

canMountSys := canMountSys(isRootless, isNewUserns, s)

if s.Privileged && canMountSys {
cgroupPerm = "rw"
Expand Down Expand Up @@ -232,6 +233,8 @@ func SpecGenToOCI(ctx context.Context, s *specgen.SpecGenerator, rt *libpod.Runt
g.AddMount(devPts)
}

inUserNS := isRootless || isNewUserns

if inUserNS && s.IpcNS.IsHost() {
g.RemoveMount("/dev/mqueue")
devMqueue := spec.Mount{
Expand Down
8 changes: 8 additions & 0 deletions test/e2e/run_ns_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -105,6 +105,14 @@ var _ = Describe("Podman run ns", func() {
Expect(session).To(ExitWithError())
})

It("podman run mounts fresh cgroup", func() {
session := podmanTest.Podman([]string{"run", fedoraMinimal, "grep", "cgroup", "/proc/self/mountinfo"})
session.WaitWithDefaultTimeout()
Expect(session.ExitCode()).To(Equal(0))
output := session.OutputToString()
Expect(output).ToNot(ContainSubstring(".."))
})

It("podman run --ipc=host --pid=host", func() {
SkipIfRootlessCgroupsV1("Not supported for rootless + CGroupsV1")
cmd := exec.Command("ls", "-l", "/proc/self/ns/pid")
Expand Down