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authorZach Koopmans <zkoopmans@google.com>2021-01-22 10:49:57 -0800
committergVisor bot <gvisor-bot@google.com>2021-01-22 10:52:57 -0800
commit16b81308cfb7cf2265d69e7180cd024f7c5b89e4 (patch)
tree59ea14fe86ca80a87d00089b93697aca7aea785a /runsc/mitigate
parent9b4f4655ed5ddcbe34806a28b2bc5d8f61fbb215 (diff)
Add initial mitigate code and cpu parsing.
PiperOrigin-RevId: 353274135
Diffstat (limited to 'runsc/mitigate')
-rw-r--r--runsc/mitigate/BUILD18
-rw-r--r--runsc/mitigate/cpu.go235
-rw-r--r--runsc/mitigate/cpu_test.go368
-rw-r--r--runsc/mitigate/mitigate.go20
4 files changed, 641 insertions, 0 deletions
diff --git a/runsc/mitigate/BUILD b/runsc/mitigate/BUILD
new file mode 100644
index 000000000..9a9546577
--- /dev/null
+++ b/runsc/mitigate/BUILD
@@ -0,0 +1,18 @@
+load("//tools:defs.bzl", "go_library", "go_test")
+
+package(licenses = ["notice"])
+
+go_library(
+ name = "mitigate",
+ srcs = [
+ "cpu.go",
+ "mitigate.go",
+ ],
+)
+
+go_test(
+ name = "mitigate_test",
+ size = "small",
+ srcs = ["cpu_test.go"],
+ library = ":mitigate",
+)
diff --git a/runsc/mitigate/cpu.go b/runsc/mitigate/cpu.go
new file mode 100644
index 000000000..113b98159
--- /dev/null
+++ b/runsc/mitigate/cpu.go
@@ -0,0 +1,235 @@
+// 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 mitigate
+
+import (
+ "fmt"
+ "regexp"
+ "strconv"
+ "strings"
+)
+
+const (
+ // constants of coomm
+ meltdown = "cpu_meltdown"
+ l1tf = "l1tf"
+ mds = "mds"
+ swapgs = "swapgs"
+ taa = "taa"
+)
+
+const (
+ processorKey = "processor"
+ vendorIDKey = "vendor_id"
+ cpuFamilyKey = "cpu family"
+ modelKey = "model"
+ coreIDKey = "core id"
+ bugsKey = "bugs"
+)
+
+// getCPUSet returns cpu structs from reading /proc/cpuinfo.
+func getCPUSet(data string) ([]*cpu, error) {
+ // Each processor entry should start with the
+ // processor key. Find the beginings of each.
+ r := buildRegex(processorKey, `\d+`)
+ indices := r.FindAllStringIndex(data, -1)
+ if len(indices) < 1 {
+ return nil, fmt.Errorf("no cpus found for: %s", data)
+ }
+
+ // Add the ending index for last entry.
+ indices = append(indices, []int{len(data), -1})
+
+ // Valid cpus are now defined by strings in between
+ // indexes (e.g. data[index[i], index[i+1]]).
+ // There should be len(indicies) - 1 CPUs
+ // since the last index is the end of the string.
+ var cpus = make([]*cpu, 0, len(indices)-1)
+ // Find each string that represents a CPU. These begin "processor".
+ for i := 1; i < len(indices); i++ {
+ start := indices[i-1][0]
+ end := indices[i][0]
+ // Parse the CPU entry, which should be between start/end.
+ c, err := getCPU(data[start:end])
+ if err != nil {
+ return nil, err
+ }
+ cpus = append(cpus, c)
+ }
+ return cpus, nil
+}
+
+// type cpu represents pertinent info about a cpu.
+type cpu struct {
+ processorNumber int64 // the processor number of this CPU.
+ vendorID string // the vendorID of CPU (e.g. AuthenticAMD).
+ cpuFamily int64 // CPU family number (e.g. 6 for CascadeLake/Skylake).
+ model int64 // CPU model number (e.g. 85 for CascadeLake/Skylake).
+ coreID int64 // This CPU's core id to match Hyperthread Pairs
+ bugs map[string]struct{} // map of vulnerabilities parsed from the 'bugs' field.
+}
+
+// getCPU parses a CPU from a single cpu entry from /proc/cpuinfo.
+func getCPU(data string) (*cpu, error) {
+ processor, err := parseProcessor(data)
+ if err != nil {
+ return nil, err
+ }
+
+ vendorID, err := parseVendorID(data)
+ if err != nil {
+ return nil, err
+ }
+
+ cpuFamily, err := parseCPUFamily(data)
+ if err != nil {
+ return nil, err
+ }
+
+ model, err := parseModel(data)
+ if err != nil {
+ return nil, err
+ }
+
+ coreID, err := parseCoreID(data)
+ if err != nil {
+ return nil, err
+ }
+
+ bugs, err := parseBugs(data)
+ if err != nil {
+ return nil, err
+ }
+
+ return &cpu{
+ processorNumber: processor,
+ vendorID: vendorID,
+ cpuFamily: cpuFamily,
+ model: model,
+ coreID: coreID,
+ bugs: bugs,
+ }, nil
+}
+
+// List of pertinent side channel vulnerablilites.
+// For mds, see: https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html.
+var vulnerabilities = []string{
+ meltdown,
+ l1tf,
+ mds,
+ swapgs,
+ taa,
+}
+
+// isVulnerable checks if a CPU is vulnerable to pertinent bugs.
+func (c *cpu) isVulnerable() bool {
+ for _, bug := range vulnerabilities {
+ if _, ok := c.bugs[bug]; ok {
+ return true
+ }
+ }
+ return false
+}
+
+// similarTo checks family/model/bugs fields for equality of two
+// processors.
+func (c *cpu) similarTo(other *cpu) bool {
+ if c.vendorID != other.vendorID {
+ return false
+ }
+
+ if other.cpuFamily != c.cpuFamily {
+ return false
+ }
+
+ if other.model != c.model {
+ return false
+ }
+
+ if len(other.bugs) != len(c.bugs) {
+ return false
+ }
+
+ for bug := range c.bugs {
+ if _, ok := other.bugs[bug]; !ok {
+ return false
+ }
+ }
+ return true
+}
+
+// parseProcessor grabs the processor field from /proc/cpuinfo output.
+func parseProcessor(data string) (int64, error) {
+ return parseIntegerResult(data, processorKey)
+}
+
+// parseVendorID grabs the vendor_id field from /proc/cpuinfo output.
+func parseVendorID(data string) (string, error) {
+ return parseRegex(data, vendorIDKey, `[\w\d]+`)
+}
+
+// parseCPUFamily grabs the cpu family field from /proc/cpuinfo output.
+func parseCPUFamily(data string) (int64, error) {
+ return parseIntegerResult(data, cpuFamilyKey)
+}
+
+// parseModel grabs the model field from /proc/cpuinfo output.
+func parseModel(data string) (int64, error) {
+ return parseIntegerResult(data, modelKey)
+}
+
+// parseCoreID parses the core id field.
+func parseCoreID(data string) (int64, error) {
+ return parseIntegerResult(data, coreIDKey)
+}
+
+// parseBugs grabs the bugs field from /proc/cpuinfo output.
+func parseBugs(data string) (map[string]struct{}, error) {
+ result, err := parseRegex(data, bugsKey, `[\d\w\s]*`)
+ if err != nil {
+ return nil, err
+ }
+ bugs := strings.Split(result, " ")
+ ret := make(map[string]struct{}, len(bugs))
+ for _, bug := range bugs {
+ ret[bug] = struct{}{}
+ }
+ return ret, nil
+}
+
+// parseIntegerResult parses fields expecting an integer.
+func parseIntegerResult(data, key string) (int64, error) {
+ result, err := parseRegex(data, key, `\d+`)
+ if err != nil {
+ return 0, err
+ }
+ return strconv.ParseInt(result, 0, 64)
+}
+
+// buildRegex builds a regex for parsing each CPU field.
+func buildRegex(key, match string) *regexp.Regexp {
+ reg := fmt.Sprintf(`(?m)^%s\s*:\s*(.*)$`, key)
+ return regexp.MustCompile(reg)
+}
+
+// parseRegex parses data with key inserted into a standard regex template.
+func parseRegex(data, key, match string) (string, error) {
+ r := buildRegex(key, match)
+ matches := r.FindStringSubmatch(data)
+ if len(matches) < 2 {
+ return "", fmt.Errorf("failed to match key %s: %s", key, data)
+ }
+ return matches[1], nil
+}
diff --git a/runsc/mitigate/cpu_test.go b/runsc/mitigate/cpu_test.go
new file mode 100644
index 000000000..77b714a02
--- /dev/null
+++ b/runsc/mitigate/cpu_test.go
@@ -0,0 +1,368 @@
+// 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 mitigate
+
+import (
+ "io/ioutil"
+ "strings"
+ "testing"
+)
+
+// CPU info for a Intel CascadeLake processor. Both Skylake and CascadeLake have
+// the same family/model numbers, but with different bugs (e.g. skylake has
+// cpu_meltdown).
+var cascadeLake = &cpu{
+ vendorID: "GenuineIntel",
+ cpuFamily: 6,
+ model: 85,
+ bugs: map[string]struct{}{
+ "spectre_v1": struct{}{},
+ "spectre_v2": struct{}{},
+ "spec_store_bypass": struct{}{},
+ mds: struct{}{},
+ swapgs: struct{}{},
+ taa: struct{}{},
+ },
+}
+
+// TestGetCPU tests basic parsing of single CPU strings from reading
+// /proc/cpuinfo.
+func TestGetCPU(t *testing.T) {
+ data := `processor : 0
+vendor_id : GenuineIntel
+cpu family : 6
+model : 85
+core id : 0
+bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs taa itlb_multihit
+`
+ want := cpu{
+ processorNumber: 0,
+ vendorID: "GenuineIntel",
+ cpuFamily: 6,
+ model: 85,
+ coreID: 0,
+ bugs: map[string]struct{}{
+ "cpu_meltdown": struct{}{},
+ "spectre_v1": struct{}{},
+ "spectre_v2": struct{}{},
+ "spec_store_bypass": struct{}{},
+ "l1tf": struct{}{},
+ "mds": struct{}{},
+ "swapgs": struct{}{},
+ "taa": struct{}{},
+ "itlb_multihit": struct{}{},
+ },
+ }
+
+ got, err := getCPU(data)
+ if err != nil {
+ t.Fatalf("getCpu failed with error: %v", err)
+ }
+
+ if !want.similarTo(got) {
+ t.Fatalf("Failed cpus not similar: got: %+v, want: %+v", got, want)
+ }
+
+ if !got.isVulnerable() {
+ t.Fatalf("Failed: cpu should be vulnerable.")
+ }
+}
+
+func TestInvalid(t *testing.T) {
+ result, err := getCPUSet(`something not a processor`)
+ if err == nil {
+ t.Fatalf("getCPU set didn't return an error: %+v", result)
+ }
+
+ if !strings.Contains(err.Error(), "no cpus") {
+ t.Fatalf("Incorrect error returned: %v", err)
+ }
+}
+
+// TestCPUSet tests getting the right number of CPUs from
+// parsing full output of /proc/cpuinfo.
+func TestCPUSet(t *testing.T) {
+ data := `processor : 0
+vendor_id : GenuineIntel
+cpu family : 6
+model : 63
+model name : Intel(R) Xeon(R) CPU @ 2.30GHz
+stepping : 0
+microcode : 0x1
+cpu MHz : 2299.998
+cache size : 46080 KB
+physical id : 0
+siblings : 2
+core id : 0
+cpu cores : 1
+apicid : 0
+initial apicid : 0
+fpu : yes
+fpu_exception : yes
+cpuid level : 13
+wp : yes
+flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht syscall nx pdpe1gb rdtscp lm constant_tsc rep_good nopl xtopology nonstop_tsc cpuid tsc_known_freq pni pclmulqdq ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm abm invpcid_single pti ssbd ibrs ibpb stibp fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid xsaveopt arat md_clear arch_capabilities
+bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs
+bogomips : 4599.99
+clflush size : 64
+cache_alignment : 64
+address sizes : 46 bits physical, 48 bits virtual
+power management:
+
+processor : 1
+vendor_id : GenuineIntel
+cpu family : 6
+model : 63
+model name : Intel(R) Xeon(R) CPU @ 2.30GHz
+stepping : 0
+microcode : 0x1
+cpu MHz : 2299.998
+cache size : 46080 KB
+physical id : 0
+siblings : 2
+core id : 0
+cpu cores : 1
+apicid : 1
+initial apicid : 1
+fpu : yes
+fpu_exception : yes
+cpuid level : 13
+wp : yes
+flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht syscall nx pdpe1gb rdtscp lm constant_tsc rep_good nopl xtopology nonstop_tsc cpuid tsc_known_freq pni pclmulqdq ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm abm invpcid_single pti ssbd ibrs ibpb stibp fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid xsaveopt arat md_clear arch_capabilities
+bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs
+bogomips : 4599.99
+clflush size : 64
+cache_alignment : 64
+address sizes : 46 bits physical, 48 bits virtual
+power management:
+`
+ cpuSet, err := getCPUSet(data)
+ if err != nil {
+ t.Fatalf("getCPUSet failed: %v", err)
+ }
+
+ wantCPULen := 2
+ if len(cpuSet) != wantCPULen {
+ t.Fatalf("Num CPU mismatch: want: %d, got: %d", wantCPULen, len(cpuSet))
+ }
+
+ wantCPU := cpu{
+ vendorID: "GenuineIntel",
+ cpuFamily: 6,
+ model: 63,
+ bugs: map[string]struct{}{
+ "cpu_meltdown": struct{}{},
+ "spectre_v1": struct{}{},
+ "spectre_v2": struct{}{},
+ "spec_store_bypass": struct{}{},
+ "l1tf": struct{}{},
+ "mds": struct{}{},
+ "swapgs": struct{}{},
+ },
+ }
+
+ for _, c := range cpuSet {
+ if !wantCPU.similarTo(c) {
+ t.Fatalf("Failed cpus not equal: got: %+v, want: %+v", c, wantCPU)
+ }
+ }
+}
+
+// TestReadFile is a smoke test for parsing methods.
+func TestReadFile(t *testing.T) {
+ data, err := ioutil.ReadFile("/proc/cpuinfo")
+ if err != nil {
+ t.Fatalf("Failed to read cpuinfo: %v", err)
+ }
+
+ set, err := getCPUSet(string(data))
+ if err != nil {
+ t.Fatalf("Failed to parse CPU data %v\n%s", err, data)
+ }
+
+ if len(set) < 1 {
+ t.Fatalf("Failed to parse any CPUs: %d", len(set))
+ }
+
+ for _, c := range set {
+ t.Logf("CPU: %+v: %t", c, c.isVulnerable())
+ }
+}
+
+// TestVulnerable tests if the isVulnerable method is correct
+// among known CPUs in GCP.
+func TestVulnerable(t *testing.T) {
+ const haswell = `processor : 0
+vendor_id : GenuineIntel
+cpu family : 6
+model : 63
+model name : Intel(R) Xeon(R) CPU @ 2.30GHz
+stepping : 0
+microcode : 0x1
+cpu MHz : 2299.998
+cache size : 46080 KB
+physical id : 0
+siblings : 4
+core id : 0
+cpu cores : 2
+apicid : 0
+initial apicid : 0
+fpu : yes
+fpu_exception : yes
+cpuid level : 13
+wp : yes
+flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht syscall nx pdpe1gb rdtscp lm constant_tsc rep_good nopl xtopology nonstop_tsc cpuid tsc_known_freq pni pclmulqdq ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm abm invpcid_single pti ssbd ibrs ibpb stibp fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid xsaveopt arat md_clear arch_capabilities
+bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs
+bogomips : 4599.99
+clflush size : 64
+cache_alignment : 64
+address sizes : 46 bits physical, 48 bits virtual
+power management:`
+
+ const skylake = `processor : 0
+vendor_id : GenuineIntel
+cpu family : 6
+model : 85
+model name : Intel(R) Xeon(R) CPU @ 2.00GHz
+stepping : 3
+microcode : 0x1
+cpu MHz : 2000.180
+cache size : 39424 KB
+physical id : 0
+siblings : 2
+core id : 0
+cpu cores : 1
+apicid : 0
+initial apicid : 0
+fpu : yes
+fpu_exception : yes
+cpuid level : 13
+wp : yes
+flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht syscall nx pdpe1gb rdtscp lm constant_tsc rep_good nopl xtopology nonstop_tsc cpuid tsc_known_freq pni pclmulqdq ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm abm 3dnowprefetch invpcid_single pti ssbd ibrs ibpb stibp fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm mpx avx512f avx512dq rdseed adx smap clflushopt clwb avx512cd avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves arat md_clear arch_capabilities
+bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs taa
+bogomips : 4000.36
+clflush size : 64
+cache_alignment : 64
+address sizes : 46 bits physical, 48 bits virtual
+power management:`
+
+ const cascade = `processor : 0
+vendor_id : GenuineIntel
+cpu family : 6
+model : 85
+model name : Intel(R) Xeon(R) CPU
+stepping : 7
+microcode : 0x1
+cpu MHz : 2800.198
+cache size : 33792 KB
+physical id : 0
+siblings : 2
+core id : 0
+cpu cores : 1
+apicid : 0
+initial apicid : 0
+fpu : yes
+fpu_exception : yes
+cpuid level : 13
+wp : yes
+flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2
+ ss ht syscall nx pdpe1gb rdtscp lm constant_tsc rep_good nopl xtopology nonstop_tsc cpuid tsc_known_freq pni pclmu
+lqdq ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm abm 3dnowpr
+efetch invpcid_single ssbd ibrs ibpb stibp ibrs_enhanced fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid r
+tm mpx avx512f avx512dq rdseed adx smap clflushopt clwb avx512cd avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves a
+rat avx512_vnni md_clear arch_capabilities
+bugs : spectre_v1 spectre_v2 spec_store_bypass mds swapgs taa
+bogomips : 5600.39
+clflush size : 64
+cache_alignment : 64
+address sizes : 46 bits physical, 48 bits virtual
+power management:`
+
+ const amd = `processor : 0
+vendor_id : AuthenticAMD
+cpu family : 23
+model : 49
+model name : AMD EPYC 7B12
+stepping : 0
+microcode : 0x1000065
+cpu MHz : 2250.000
+cache size : 512 KB
+physical id : 0
+siblings : 2
+core id : 0
+cpu cores : 1
+apicid : 0
+initial apicid : 0
+fpu : yes
+fpu_exception : yes
+cpuid level : 13
+wp : yes
+flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl xtopology nonstop_tsc cpuid extd_apicid tsc_known_freq pni pclmulqdq ssse3 fma cx16 sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm cmp_legacy cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw topoext ssbd ibrs ibpb stibp vmmcall fsgsbase tsc_adjust bmi1 avx2 smep bmi2 rdseed adx smap clflushopt clwb sha_ni xsaveopt xsavec xgetbv1 clzero xsaveerptr arat npt nrip_save umip rdpid
+bugs : sysret_ss_attrs spectre_v1 spectre_v2 spec_store_bypass
+bogomips : 4500.00
+TLB size : 3072 4K pages
+clflush size : 64
+cache_alignment : 64
+address sizes : 48 bits physical, 48 bits virtual
+power management:`
+
+ for _, tc := range []struct {
+ name string
+ cpuString string
+ vulnerable bool
+ }{
+ {
+ name: "haswell",
+ cpuString: haswell,
+ vulnerable: true,
+ }, {
+ name: "skylake",
+ cpuString: skylake,
+ vulnerable: true,
+ }, {
+ name: "cascadeLake",
+ cpuString: cascade,
+ vulnerable: false,
+ }, {
+ name: "amd",
+ cpuString: amd,
+ vulnerable: false,
+ },
+ } {
+ t.Run(tc.name, func(t *testing.T) {
+ set, err := getCPUSet(tc.cpuString)
+ if err != nil {
+ t.Fatalf("Failed to getCPUSet:%v\n %s", err, tc.cpuString)
+ }
+
+ if len(set) < 1 {
+ t.Fatalf("Returned empty cpu set: %v", set)
+ }
+
+ for _, c := range set {
+ got := func() bool {
+ if cascadeLake.similarTo(c) {
+ return false
+ }
+ return c.isVulnerable()
+ }()
+
+ if got != tc.vulnerable {
+ t.Fatalf("Mismatch vulnerable for cpu %+s: got %t want: %t", tc.name, tc.vulnerable, got)
+ }
+ }
+ })
+ }
+}
diff --git a/runsc/mitigate/mitigate.go b/runsc/mitigate/mitigate.go
new file mode 100644
index 000000000..51d5449b6
--- /dev/null
+++ b/runsc/mitigate/mitigate.go
@@ -0,0 +1,20 @@
+// 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 mitigate provides libraries for the mitigate command. The
+// mitigate command mitigates side channel attacks such as MDS. Mitigate
+// shuts down CPUs via /sys/devices/system/cpu/cpu{N}/online. In addition,
+// the mitigate also handles computing available CPU in kubernetes kube_config
+// files.
+package mitigate