Allow default control values to be set for cgroupfs.

PiperOrigin-RevId: 366891806

pkg/sentry/fsimpl/cgroupfs/cgroupfs.go

@@ -94,6 +94,14 @@ var SupportedMountOptions = []string{"all", "cpu", "cpuacct", "cpuset", "memory"
 // +stateify savable
 type FilesystemType struct{}
 
+// InternalData contains internal data passed in to the cgroupfs mount via
+// vfs.GetFilesystemOptions.InternalData.
+//
+// +stateify savable
+type InternalData struct {
+	DefaultControlValues map[string]int64
+}
+
 // filesystem implements vfs.FilesystemImpl.
 //
 // +stateify savable
@@ -218,13 +226,19 @@ func (fsType FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
 	fs.MaxCachedDentries = maxCachedDentries
 	fs.VFSFilesystem().Init(vfsObj, &fsType, fs)
 
+	var defaults map[string]int64
+	if opts.InternalData != nil {
+		ctx.Debugf("cgroupfs.FilesystemType.GetFilesystem: default control values: %v", defaults)
+		defaults = opts.InternalData.(*InternalData).DefaultControlValues
+	}
+
 	for _, ty := range wantControllers {
 		var c controller
 		switch ty {
 		case controllerMemory:
-			c = newMemoryController(fs)
+			c = newMemoryController(fs, defaults)
 		case controllerCPU:
-			c = newCPUController(fs)
+			c = newCPUController(fs, defaults)
 		case controllerCPUAcct:
 			c = newCPUAcctController(fs)
 		case controllerCPUSet:
@@ -235,6 +249,12 @@ func (fsType FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
 		fs.controllers = append(fs.controllers, c)
 	}
 
+	if len(defaults) != 0 {
+		// Internal data is always provided at sentry startup and unused values
+		// indicate a problem with the sandbox config. Fail fast.
+		panic(fmt.Sprintf("cgroupfs.FilesystemType.GetFilesystem: unknown internal mount data: %v", defaults))
+	}
+
 	// Controllers usually appear in alphabetical order when displayed. Sort it
 	// here now, so it never needs to be sorted elsewhere.
 	sort.Slice(fs.controllers, func(i, j int) bool { return fs.controllers[i].Type() < fs.controllers[j].Type() })

pkg/sentry/fsimpl/cgroupfs/cpu.go

@@ -28,22 +28,36 @@ type cpuController struct {
 	controllerCommon
 
 	// CFS bandwidth control parameters, values in microseconds.
-	cfsPeriod uint64
+	cfsPeriod int64
 	cfsQuota  int64
 
 	// CPU shares, values should be (num core * 1024).
-	shares uint64
+	shares int64
 }
 
 var _ controller = (*cpuController)(nil)
 
-func newCPUController(fs *filesystem) *cpuController {
+func newCPUController(fs *filesystem, defaults map[string]int64) *cpuController {
 	// Default values for controller parameters from Linux.
 	c := &cpuController{
 		cfsPeriod: 100000,
 		cfsQuota:  -1,
 		shares:    1024,
 	}
+
+	if val, ok := defaults["cpu.cfs_period_us"]; ok {
+		c.cfsPeriod = val
+		delete(defaults, "cpu.cfs_period_us")
+	}
+	if val, ok := defaults["cpu.cfs_quota_us"]; ok {
+		c.cfsQuota = val
+		delete(defaults, "cpu.cfs_quota_us")
+	}
+	if val, ok := defaults["cpu.shares"]; ok {
+		c.shares = val
+		delete(defaults, "cpu.shares")
+	}
+
 	c.controllerCommon.init(controllerCPU, fs)
 	return c
 }

pkg/sentry/fsimpl/cgroupfs/memory.go

@@ -17,7 +17,9 @@ package cgroupfs
 import (
 	"bytes"
 	"fmt"
+	"math"
 
+	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
@@ -28,12 +30,23 @@ import (
 // +stateify savable
 type memoryController struct {
 	controllerCommon
+
+	limitBytes int64
 }
 
 var _ controller = (*memoryController)(nil)
 
-func newMemoryController(fs *filesystem) *memoryController {
-	c := &memoryController{}
+func newMemoryController(fs *filesystem, defaults map[string]int64) *memoryController {
+	c := &memoryController{
+		// Linux sets this to (PAGE_COUNTER_MAX * PAGE_SIZE) by default, which
+		// is ~ 2**63 on a 64-bit system. So essentially, inifinity. The exact
+		// value isn't very important.
+		limitBytes: math.MaxInt64,
+	}
+	if val, ok := defaults["memory.limit_in_bytes"]; ok {
+		c.limitBytes = val
+		delete(defaults, "memory.limit_in_bytes")
+	}
 	c.controllerCommon.init(controllerMemory, fs)
 	return c
 }
@@ -41,6 +54,7 @@ func newMemoryController(fs *filesystem) *memoryController {
 // AddControlFiles implements controller.AddControlFiles.
 func (c *memoryController) AddControlFiles(ctx context.Context, creds *auth.Credentials, _ *cgroupInode, contents map[string]kernfs.Inode) {
 	contents["memory.usage_in_bytes"] = c.fs.newControllerFile(ctx, creds, &memoryUsageInBytesData{})
+	contents["memory.limit_in_bytes"] = c.fs.newStaticControllerFile(ctx, creds, linux.FileMode(0644), fmt.Sprintf("%d\n", c.limitBytes))
 }
 
 // +stateify savable