Major refactor of runsc mitigate.

PiperOrigin-RevId: 362360425

3 files changed, 287 insertions, 7 deletions

diff --git a/runsc/cmd/BUILD b/runsc/cmd/BUILD
index e3e289da3..2c3b4058b 100644
--- a/runsc/cmd/BUILD
+++ b/runsc/cmd/BUILD
@@ -77,6 +77,7 @@ go_test(
         "delete_test.go",
         "exec_test.go",
         "gofer_test.go",
+        "mitigate_test.go",
     ],
     data = [
         "//runsc",
@@ -91,6 +92,8 @@ go_test(
         "//pkg/urpc",
         "//runsc/config",
         "//runsc/container",
+        "//runsc/mitigate",
+        "//runsc/mitigate/mock",
         "//runsc/specutils",
         "@com_github_google_go_cmp//cmp:go_default_library",
         "@com_github_google_go_cmp//cmp/cmpopts:go_default_library",
diff --git a/runsc/cmd/mitigate.go b/runsc/cmd/mitigate.go
index 822af1917..fddf0e0dd 100644
--- a/runsc/cmd/mitigate.go
+++ b/runsc/cmd/mitigate.go
@@ -16,6 +16,8 @@ package cmd
 
 import (
 	"context"
+	"fmt"
+	"io/ioutil"
 
 	"github.com/google/subcommands"
 	"gvisor.dev/gvisor/pkg/log"
@@ -23,9 +25,23 @@ import (
 	"gvisor.dev/gvisor/runsc/mitigate"
 )
 
+const (
+	// cpuInfo is the path used to parse CPU info.
+	cpuInfo = "/proc/cpuinfo"
+	// allPossibleCPUs is the path used to enable CPUs.
+	allPossibleCPUs = "/sys/devices/system/cpu/possible"
+)
+
 // Mitigate implements subcommands.Command for the "mitigate" command.
 type Mitigate struct {
-	mitigate mitigate.Mitigate
+	// Run the command without changing the underlying system.
+	dryRun bool
+	// Reverse mitigate by turning on all CPU cores.
+	reverse bool
+	// Path to file to read to create CPUSet.
+	path string
+	// Callback to check if a given thread is vulnerable.
+	vulnerable func(other mitigate.Thread) bool
 }
 
 // Name implements subcommands.command.name.
@@ -38,14 +54,19 @@ func (*Mitigate) Synopsis() string {
 	return "mitigate mitigates the underlying system against side channel attacks"
 }
 
-// Usage implements subcommands.Command.Usage.
-func (m *Mitigate) Usage() string {
-	return m.mitigate.Usage()
+// Usage implments Usage for cmd.Mitigate.
+func (m Mitigate) Usage() string {
+	return `mitigate [flags]
+
+mitigate mitigates a system to the "MDS" vulnerability by implementing a manual shutdown of SMT. The command checks /proc/cpuinfo for cpus having the MDS vulnerability, and if found, shutdown all but one CPU per hyperthread pair via /sys/devices/system/cpu/cpu{N}/online. CPUs can be restored by writing "2" to each file in /sys/devices/system/cpu/cpu{N}/online or performing a system reboot.
+
+The command can be reversed with --reverse, which reads the total CPUs from /sys/devices/system/cpu/possible and enables all with /sys/devices/system/cpu/cpu{N}/online.`
 }
 
-// SetFlags implements subcommands.Command.SetFlags.
+// SetFlags sets flags for the command Mitigate.
 func (m *Mitigate) SetFlags(f *flag.FlagSet) {
-	m.mitigate.SetFlags(f)
+	f.BoolVar(&m.dryRun, "dryrun", false, "run the command without changing system")
+	f.BoolVar(&m.reverse, "reverse", false, "reverse mitigate by enabling all CPUs")
 }
 
 // Execute implements subcommands.Command.Execute.
@@ -55,10 +76,97 @@ func (m *Mitigate) Execute(_ context.Context, f *flag.FlagSet, args ...interface
 		return subcommands.ExitUsageError
 	}
 
-	if err := m.mitigate.Execute(); err != nil {
+	m.path = cpuInfo
+	if m.reverse {
+		m.path = allPossibleCPUs
+	}
+
+	m.vulnerable = func(other mitigate.Thread) bool {
+		return other.IsVulnerable()
+	}
+
+	if _, err := m.doExecute(); err != nil {
 		log.Warningf("Execute failed: %v", err)
 		return subcommands.ExitFailure
 	}
 
 	return subcommands.ExitSuccess
 }
+
+// Execute executes the Mitigate command.
+func (m *Mitigate) doExecute() (mitigate.CPUSet, error) {
+	if m.dryRun {
+		log.Infof("Running with DryRun. No cpu settings will be changed.")
+	}
+	if m.reverse {
+		data, err := ioutil.ReadFile(m.path)
+		if err != nil {
+			return nil, fmt.Errorf("failed to read %s: %v", m.path, err)
+		}
+
+		set, err := m.doReverse(data)
+		if err != nil {
+			return nil, fmt.Errorf("reverse operation failed: %v", err)
+		}
+		return set, nil
+	}
+
+	data, err := ioutil.ReadFile(m.path)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read %s: %v", m.path, err)
+	}
+	set, err := m.doMitigate(data)
+	if err != nil {
+		return nil, fmt.Errorf("mitigate operation failed: %v", err)
+	}
+	return set, nil
+}
+
+func (m *Mitigate) doMitigate(data []byte) (mitigate.CPUSet, error) {
+	set, err := mitigate.NewCPUSet(data, m.vulnerable)
+	if err != nil {
+		return nil, err
+	}
+
+	log.Infof("Mitigate found the following CPUs...")
+	log.Infof("%s", set)
+
+	disableList := set.GetShutdownList()
+	log.Infof("Disabling threads on thread pairs.")
+	for _, t := range disableList {
+		log.Infof("Disable thread: %s", t)
+		if m.dryRun {
+			continue
+		}
+		if err := t.Disable(); err != nil {
+			return nil, fmt.Errorf("error disabling thread: %s err: %v", t, err)
+		}
+	}
+	log.Infof("Shutdown successful.")
+	return set, nil
+}
+
+func (m *Mitigate) doReverse(data []byte) (mitigate.CPUSet, error) {
+	set, err := mitigate.NewCPUSetFromPossible(data)
+	if err != nil {
+		return nil, err
+	}
+
+	log.Infof("Reverse mitigate found the following CPUs...")
+	log.Infof("%s", set)
+
+	enableList := set.GetRemainingList()
+
+	log.Infof("Enabling all CPUs...")
+	for _, t := range enableList {
+		log.Infof("Enabling thread: %s", t)
+		if m.dryRun {
+			continue
+		}
+		if err := t.Enable(); err != nil {
+			return nil, fmt.Errorf("error enabling thread: %s err: %v", t, err)
+		}
+	}
+	log.Infof("Enable successful.")
+	return set, nil
+}
diff --git a/runsc/cmd/mitigate_test.go b/runsc/cmd/mitigate_test.go
new file mode 100644
index 000000000..163fece42
--- /dev/null
+++ b/runsc/cmd/mitigate_test.go
@@ -0,0 +1,169 @@
+// Copyright 2021 The gVisor 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.
+
+package cmd
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"strings"
+	"testing"
+
+	"gvisor.dev/gvisor/runsc/mitigate"
+	"gvisor.dev/gvisor/runsc/mitigate/mock"
+)
+
+type executeTestCase struct {
+	name          string
+	mitigateData  string
+	mitigateError error
+	mitigateCPU   int
+	reverseData   string
+	reverseError  error
+	reverseCPU    int
+}
+
+func TestExecute(t *testing.T) {
+
+	partial := `processor       : 1
+vendor_id       : AuthenticAMD
+cpu family      : 23
+model           : 49
+model name      : AMD EPYC 7B12
+physical id     : 0
+bugs         : sysret_ss_attrs spectre_v1 spectre_v2 spec_store_bypass
+power management:
+`
+
+	for _, tc := range []executeTestCase{
+		{
+			name:         "CascadeLake4",
+			mitigateData: mock.CascadeLake4.MakeCPUString(),
+			mitigateCPU:  2,
+			reverseData:  mock.CascadeLake4.MakeSysPossibleString(),
+			reverseCPU:   4,
+		},
+		{
+			name:          "Empty",
+			mitigateData:  "",
+			mitigateError: fmt.Errorf(`mitigate operation failed: no cpus found for: ""`),
+			reverseData:   "",
+			reverseError:  fmt.Errorf(`reverse operation failed: mismatch regex from possible: ""`),
+		},
+		{
+			name: "Partial",
+			mitigateData: `processor       : 0
+vendor_id       : AuthenticAMD
+cpu family      : 23
+model           : 49
+model name      : AMD EPYC 7B12
+physical id     : 0
+core id         : 0
+cpu cores       : 1
+bugs            : sysret_ss_attrs spectre_v1 spectre_v2 spec_store_bypass
+power management::84
+
+` + partial,
+			mitigateError: fmt.Errorf(`mitigate operation failed: failed to match key "core id": %q`, partial),
+			reverseData:   "1-",
+			reverseError:  fmt.Errorf(`reverse operation failed: mismatch regex from possible: %q`, "1-"),
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			m := &Mitigate{
+				dryRun: true,
+				vulnerable: func(other mitigate.Thread) bool {
+					return other.IsVulnerable()
+				},
+			}
+			m.doExecuteTest(t, "Mitigate", tc.mitigateData, tc.mitigateCPU, tc.mitigateError)
+
+			m.reverse = true
+			m.doExecuteTest(t, "Reverse", tc.reverseData, tc.reverseCPU, tc.reverseError)
+		})
+	}
+}
+
+func TestExecuteSmoke(t *testing.T) {
+	smokeMitigate, err := ioutil.ReadFile(cpuInfo)
+	if err != nil {
+		t.Fatalf("Failed to read %s: %v", cpuInfo, err)
+	}
+
+	m := &Mitigate{
+		dryRun: true,
+		vulnerable: func(other mitigate.Thread) bool {
+			return other.IsVulnerable()
+		},
+	}
+
+	m.doExecuteTest(t, "Mitigate", string(smokeMitigate), 0, nil)
+
+	smokeReverse, err := ioutil.ReadFile(allPossibleCPUs)
+	if err != nil {
+		t.Fatalf("Failed to read %s: %v", allPossibleCPUs, err)
+	}
+
+	m.reverse = true
+	m.doExecuteTest(t, "Reverse", string(smokeReverse), 0, nil)
+}
+
+// doExecuteTest runs Execute with the mitigate operation and reverse operation.
+func (m *Mitigate) doExecuteTest(t *testing.T, name, data string, want int, wantErr error) {
+	t.Run(name, func(t *testing.T) {
+		file, err := ioutil.TempFile("", "outfile.txt")
+		if err != nil {
+			t.Fatalf("Failed to create tmpfile: %v", err)
+		}
+		defer os.Remove(file.Name())
+
+		if _, err := file.WriteString(data); err != nil {
+			t.Fatalf("Failed to write to file: %v", err)
+		}
+
+		// Set fields for mitigate and dryrun to keep test hermetic.
+		m.path = file.Name()
+
+		set, err := m.doExecute()
+		if err = checkErr(wantErr, err); err != nil {
+			t.Fatalf("Mitigate error mismatch: %v", err)
+		}
+
+		// case where test should end in error or we don't care
+		// about how many cpus are returned.
+		if wantErr != nil || want < 1 {
+			return
+		}
+		got := len(set.GetRemainingList())
+		if want != got {
+			t.Fatalf("Failed wrong number of remaining CPUs: want %d, got %d", want, got)
+		}
+
+	})
+}
+
+// checkErr checks error for equality.
+func checkErr(want, got error) error {
+	switch {
+	case want == nil && got == nil:
+	case want != nil && got == nil:
+		fallthrough
+	case want == nil && got != nil:
+		fallthrough
+	case want.Error() != strings.Trim(got.Error(), " "):
+		return fmt.Errorf("got: %v want: %v", got, want)
+	}
+	return nil
+}