fix(charts): disable KVM nested virtualization in Talos presets (CVE-2026-53359) #224
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,160 @@ | ||
| // Copyright Cozystack 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. | ||
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| // Contract: CVE-2026-53359 KVM-nested-virtualization mitigation in the | ||
| // cozystack and generic presets. kvm_intel/kvm_amd are built into the | ||
| // Talos kernel, so nested= is settable only from the kernel command | ||
| // line; both presets pin it via machine.install.extraKernelArgs. | ||
| // | ||
| // On Talos >1.11 the generated base config defaults | ||
| // machine.install.grubUseUKICmdline to true (UKI cmdline), and Talos | ||
| // rejects extraKernelArgs alongside it. The presets therefore pin | ||
| // grubUseUKICmdline:false wherever the base would set it true. The | ||
| // full-pipeline test below renders through engine.Render (base bundle + | ||
| // preset patch) and runs Talos's own validation to prove the merged | ||
| // config the operator applies does not trip the UKI conflict. | ||
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| package engine | ||
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| import ( | ||
| "context" | ||
| "strings" | ||
| "testing" | ||
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| helmEngine "github.com/cozystack/talm/pkg/engine/helm" | ||
| "github.com/siderolabs/talos/pkg/machinery/config/configloader" | ||
| ) | ||
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| // kvmNestedRuntimeMode is a minimal validation.RuntimeMode implementation. | ||
| // RequiresInstall() true selects the install-mode validation branch that | ||
| // enforces the extraKernelArgs/grubUseUKICmdline mutual exclusion. | ||
| type kvmNestedRuntimeMode struct{ requiresInstall bool } | ||
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| func (m kvmNestedRuntimeMode) String() string { return "kvm-nested-contract" } | ||
| func (m kvmNestedRuntimeMode) RequiresInstall() bool { return m.requiresInstall } | ||
| func (kvmNestedRuntimeMode) InContainer() bool { return false } | ||
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| // Contract: both presets always emit the KVM nested-virt kernel args | ||
| // under machine.install, for every chart × schema × machineType cell. | ||
| // A regression that drops them silently re-exposes the guest-to-host | ||
| // escape on every node the preset installs. | ||
| func TestContract_Machine_Install_KVMNestedArgs(t *testing.T) { | ||
| for _, cell := range allCells() { | ||
| t.Run(cell.name, func(t *testing.T) { | ||
| out := renderChartTemplate(t, cell.chartPath, cell.templateFile, cell.talosVersion) | ||
| assertContains(t, out, "extraKernelArgs:") | ||
| assertContains(t, out, "kvm_intel.nested=0") | ||
| assertContains(t, out, "kvm_amd.nested=0") | ||
| }) | ||
| } | ||
| } | ||
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| // Contract: grubUseUKICmdline:false is emitted exactly where the | ||
| // generated base config would default it to true — i.e. when no | ||
| // --talos-version is pinned (the bundle falls back to the current | ||
| // contract, >1.11) or when the pinned version is >=1.12. For an | ||
| // explicit pre-1.12 version the field is omitted, both because the base | ||
| // does not set it and because older Talos schemas reject the key. | ||
| func TestContract_Machine_Install_GrubUKICmdlineGate(t *testing.T) { | ||
| for _, tc := range []struct { | ||
| talosVersion string | ||
| wantField bool | ||
| }{ | ||
| {"", true}, // empty → base uses current contract (>1.11) → pin false | ||
| {"v1.12.0", true}, // >=1.12 → base defaults true → pin false | ||
| {"v1.13.0", true}, // >=1.12 → base defaults true → pin false | ||
| {"v1.11.0", false}, // <1.12 → base leaves it unset → do not emit | ||
| } { | ||
| name := tc.talosVersion | ||
| if name == "" { | ||
| name = "empty" | ||
| } | ||
| t.Run(name, func(t *testing.T) { | ||
| out := renderChartTemplate(t, cozystackChartPath, controlplaneTpl, tc.talosVersion) | ||
| if tc.wantField { | ||
| assertContains(t, out, "grubUseUKICmdline: false") | ||
| } else { | ||
| assertNotContains(t, out, "grubUseUKICmdline") | ||
| } | ||
| }) | ||
| } | ||
| } | ||
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| // Contract: the FULL config an operator applies — base bundle merged | ||
| // with the preset patch, exactly what `talm apply` serialises (Full: | ||
| // true) — passes Talos validation without the UKI/extraKernelArgs | ||
| // conflict, for both presets and both machine types on v1.12+. | ||
| // | ||
| // This is the regression guard for the whole mitigation: the raw Helm | ||
| // output above never carries grubUseUKICmdline (the base bundle injects | ||
| // it), so only a full-pipeline render surfaces the collision. Offline | ||
| // discovery leaves install.disk empty, which trips a separate | ||
| // validation error, so the assertion is scoped to the UKI conflict | ||
| // specifically rather than "no errors at all". | ||
| func TestContract_Machine_Install_FullConfigValidates_NoUKIConflict(t *testing.T) { | ||
| // Offline render still consults the Helm `lookup`; reset it to the | ||
| // empty stub so no live discovery is attempted. | ||
| helmEngine.LookupFunc = func(string, string, string) (map[string]any, error) { | ||
| return map[string]any{}, nil | ||
| } | ||
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| const ukiConflict = "grubUseUKICmdline" | ||
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| cells := []struct { | ||
| name string | ||
| chartPath string | ||
| templateFile string | ||
| }{ | ||
| {"cozystack/controlplane", cozystackChartPath, controlplaneTpl}, | ||
| {"cozystack/worker", cozystackChartPath, workerTpl}, | ||
| {"generic/controlplane", genericChartPath, controlplaneTpl}, | ||
| {"generic/worker", genericChartPath, workerTpl}, | ||
| } | ||
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| for _, cell := range cells { | ||
| t.Run(cell.name, func(t *testing.T) { | ||
| out, err := Render(context.Background(), nil, Options{ | ||
| Offline: true, | ||
| Full: true, | ||
| Root: cell.chartPath, | ||
| TalosVersion: "v1.12.0", | ||
| TemplateFiles: []string{cell.templateFile}, | ||
| Values: []string{ | ||
| "endpoint=" + testEndpoint, | ||
| "advertisedSubnets={" + testAdvertisedSubnet + "}", | ||
| }, | ||
| }) | ||
| if err != nil { | ||
| t.Fatalf("full render failed: %v", err) | ||
| } | ||
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| got := string(out) | ||
| assertContains(t, got, "grubUseUKICmdline: false") | ||
| assertContains(t, got, "kvm_intel.nested=0") | ||
| if strings.Contains(got, "grubUseUKICmdline: true") { | ||
| t.Fatalf("full config still carries grubUseUKICmdline: true — UKI cmdline not disabled:\n%s", got) | ||
| } | ||
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| cfg, lerr := configloader.NewFromBytes(out) | ||
| if lerr != nil { | ||
| t.Fatalf("config loader rejected the rendered config: %v", lerr) | ||
| } | ||
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| _, verr := cfg.Validate(kvmNestedRuntimeMode{requiresInstall: true}) | ||
| if verr != nil && strings.Contains(verr.Error(), ukiConflict) { | ||
| t.Fatalf("Talos validation reports the UKI/extraKernelArgs conflict — apply would fail: %v", verr) | ||
| } | ||
| }) | ||
| } | ||
| } |
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To maintain consistency with other customizable fields (such as
extraKernelModules,extraSysctls, etc.) and to allow operators to customize kernel arguments or override this mitigation if needed, consider adding support for an optionalextraKernelArgslist in.Values.