271 lines
		
	
	
		
			9.1 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
			
		
		
	
	
			271 lines
		
	
	
		
			9.1 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
/*
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   Copyright The containerd Authors.
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   Licensed under the Apache License, Version 2.0 (the "License");
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   you may not use this file except in compliance with the License.
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   You may obtain a copy of the License at
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       http://www.apache.org/licenses/LICENSE-2.0
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   Unless required by applicable law or agreed to in writing, software
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   distributed under the License is distributed on an "AS IS" BASIS,
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   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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   See the License for the specific language governing permissions and
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   limitations under the License.
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*/
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package server
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import (
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	"bufio"
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	"errors"
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	"fmt"
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	"io"
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	"os"
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	"strconv"
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	"strings"
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	imagespec "github.com/opencontainers/image-spec/specs-go/v1"
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	runtime "k8s.io/cri-api/pkg/apis/runtime/v1"
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	"github.com/containerd/containerd/v2/contrib/apparmor"
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	"github.com/containerd/containerd/v2/contrib/seccomp"
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	"github.com/containerd/containerd/v2/oci"
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	"github.com/containerd/containerd/v2/snapshots"
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	customopts "github.com/containerd/containerd/v2/pkg/cri/opts"
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)
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const (
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	// profileNamePrefix is the prefix for loading profiles on a localhost. Eg. AppArmor localhost/profileName.
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	profileNamePrefix = "localhost/" // TODO (mikebrow): get localhost/ & runtime/default from CRI kubernetes/kubernetes#51747
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	// runtimeDefault indicates that we should use or create a runtime default profile.
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	runtimeDefault = "runtime/default"
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	// dockerDefault indicates that we should use or create a docker default profile.
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	dockerDefault = "docker/default"
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	// appArmorDefaultProfileName is name to use when creating a default apparmor profile.
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	appArmorDefaultProfileName = "cri-containerd.apparmor.d"
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	// unconfinedProfile is a string indicating one should run a pod/containerd without a security profile
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	unconfinedProfile = "unconfined"
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	// seccompDefaultProfile is the default seccomp profile.
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	seccompDefaultProfile = dockerDefault
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)
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func (c *criService) containerSpecOpts(config *runtime.ContainerConfig, imageConfig *imagespec.ImageConfig) ([]oci.SpecOpts, error) {
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	var (
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		specOpts []oci.SpecOpts
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		err      error
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	)
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	securityContext := config.GetLinux().GetSecurityContext()
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	userstr := "0" // runtime default
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	if securityContext.GetRunAsUsername() != "" {
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		userstr = securityContext.GetRunAsUsername()
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	} else if securityContext.GetRunAsUser() != nil {
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		userstr = strconv.FormatInt(securityContext.GetRunAsUser().GetValue(), 10)
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	} else if imageConfig.User != "" {
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		userstr, _, _ = strings.Cut(imageConfig.User, ":")
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	}
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	specOpts = append(specOpts, customopts.WithAdditionalGIDs(userstr),
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		customopts.WithSupplementalGroups(securityContext.GetSupplementalGroups()))
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	asp := securityContext.GetApparmor()
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	if asp == nil {
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		asp, err = generateApparmorSecurityProfile(securityContext.GetApparmorProfile()) //nolint:staticcheck // Deprecated but we don't want to remove yet
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		if err != nil {
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			return nil, fmt.Errorf("failed to generate apparmor spec opts: %w", err)
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		}
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	}
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	apparmorSpecOpts, err := generateApparmorSpecOpts(
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		asp,
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		securityContext.GetPrivileged(),
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		c.apparmorEnabled())
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	if err != nil {
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		return nil, fmt.Errorf("failed to generate apparmor spec opts: %w", err)
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	}
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	if apparmorSpecOpts != nil {
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		specOpts = append(specOpts, apparmorSpecOpts)
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	}
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	ssp := securityContext.GetSeccomp()
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	if ssp == nil {
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		ssp, err = generateSeccompSecurityProfile(
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			securityContext.GetSeccompProfilePath(), //nolint:staticcheck // Deprecated but we don't want to remove yet
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			c.config.UnsetSeccompProfile)
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		if err != nil {
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			return nil, fmt.Errorf("failed to generate seccomp spec opts: %w", err)
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		}
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	}
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	seccompSpecOpts, err := c.generateSeccompSpecOpts(
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		ssp,
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		securityContext.GetPrivileged(),
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		c.seccompEnabled())
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	if err != nil {
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		return nil, fmt.Errorf("failed to generate seccomp spec opts: %w", err)
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	}
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	if seccompSpecOpts != nil {
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		specOpts = append(specOpts, seccompSpecOpts)
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	}
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	if c.config.EnableCDI {
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		specOpts = append(specOpts, customopts.WithCDI(config.Annotations, config.CDIDevices))
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	}
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	return specOpts, nil
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}
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func generateSeccompSecurityProfile(profilePath string, unsetProfilePath string) (*runtime.SecurityProfile, error) {
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	if profilePath != "" {
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		return generateSecurityProfile(profilePath)
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	}
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	if unsetProfilePath != "" {
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		return generateSecurityProfile(unsetProfilePath)
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	}
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	return nil, nil
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}
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func generateApparmorSecurityProfile(profilePath string) (*runtime.SecurityProfile, error) {
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	if profilePath != "" {
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		return generateSecurityProfile(profilePath)
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	}
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	return nil, nil
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}
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func generateSecurityProfile(profilePath string) (*runtime.SecurityProfile, error) {
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	switch profilePath {
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	case runtimeDefault, dockerDefault, "":
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		return &runtime.SecurityProfile{
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			ProfileType: runtime.SecurityProfile_RuntimeDefault,
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		}, nil
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	case unconfinedProfile:
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		return &runtime.SecurityProfile{
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			ProfileType: runtime.SecurityProfile_Unconfined,
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		}, nil
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	default:
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		// Require and Trim default profile name prefix
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		if !strings.HasPrefix(profilePath, profileNamePrefix) {
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			return nil, fmt.Errorf("invalid profile %q", profilePath)
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		}
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		return &runtime.SecurityProfile{
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			ProfileType:  runtime.SecurityProfile_Localhost,
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			LocalhostRef: strings.TrimPrefix(profilePath, profileNamePrefix),
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		}, nil
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	}
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}
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// generateSeccompSpecOpts generates containerd SpecOpts for seccomp.
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func (c *criService) generateSeccompSpecOpts(sp *runtime.SecurityProfile, privileged, seccompEnabled bool) (oci.SpecOpts, error) {
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	if privileged {
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		// Do not set seccomp profile when container is privileged
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		return nil, nil
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	}
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	if !seccompEnabled {
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		if sp != nil {
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			if sp.ProfileType != runtime.SecurityProfile_Unconfined {
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				return nil, errors.New("seccomp is not supported")
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			}
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		}
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		return nil, nil
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	}
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	if sp == nil {
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		return nil, nil
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	}
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	if sp.ProfileType != runtime.SecurityProfile_Localhost && sp.LocalhostRef != "" {
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		return nil, errors.New("seccomp config invalid LocalhostRef must only be set if ProfileType is Localhost")
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	}
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	switch sp.ProfileType {
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	case runtime.SecurityProfile_Unconfined:
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		// Do not set seccomp profile.
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		return nil, nil
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	case runtime.SecurityProfile_RuntimeDefault:
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		return seccomp.WithDefaultProfile(), nil
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	case runtime.SecurityProfile_Localhost:
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		// trimming the localhost/ prefix just in case even though it should not
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		// be necessary with the new SecurityProfile struct
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		return seccomp.WithProfile(strings.TrimPrefix(sp.LocalhostRef, profileNamePrefix)), nil
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	default:
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		return nil, errors.New("seccomp unknown ProfileType")
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	}
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}
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// generateApparmorSpecOpts generates containerd SpecOpts for apparmor.
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func generateApparmorSpecOpts(sp *runtime.SecurityProfile, privileged, apparmorEnabled bool) (oci.SpecOpts, error) {
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	if !apparmorEnabled {
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		// Should fail loudly if user try to specify apparmor profile
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		// but we don't support it.
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		if sp != nil {
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			if sp.ProfileType != runtime.SecurityProfile_Unconfined {
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				return nil, errors.New("apparmor is not supported")
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			}
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		}
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		return nil, nil
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	}
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	if sp == nil {
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		// Based on kubernetes#51746, default apparmor profile should be applied
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		// for when apparmor is not specified.
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		sp, _ = generateSecurityProfile("")
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	}
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	if sp.ProfileType != runtime.SecurityProfile_Localhost && sp.LocalhostRef != "" {
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		return nil, errors.New("apparmor config invalid LocalhostRef must only be set if ProfileType is Localhost")
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	}
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	switch sp.ProfileType {
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	case runtime.SecurityProfile_Unconfined:
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		// Do not set apparmor profile.
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		return nil, nil
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	case runtime.SecurityProfile_RuntimeDefault:
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		if privileged {
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			// Do not set apparmor profile when container is privileged
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			return nil, nil
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		}
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		// TODO (mikebrow): delete created apparmor default profile
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		return apparmor.WithDefaultProfile(appArmorDefaultProfileName), nil
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	case runtime.SecurityProfile_Localhost:
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		// trimming the localhost/ prefix just in case even through it should not
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		// be necessary with the new SecurityProfile struct
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		appArmorProfile := strings.TrimPrefix(sp.LocalhostRef, profileNamePrefix)
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		if profileExists, err := appArmorProfileExists(appArmorProfile); !profileExists {
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			if err != nil {
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				return nil, fmt.Errorf("failed to generate apparmor spec opts: %w", err)
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			}
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			return nil, fmt.Errorf("apparmor profile not found %s", appArmorProfile)
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		}
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		return apparmor.WithProfile(appArmorProfile), nil
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	default:
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		return nil, errors.New("apparmor unknown ProfileType")
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	}
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}
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// appArmorProfileExists scans apparmor/profiles for the requested profile
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func appArmorProfileExists(profile string) (bool, error) {
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	if profile == "" {
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		return false, errors.New("nil apparmor profile is not supported")
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	}
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	profiles, err := os.Open("/sys/kernel/security/apparmor/profiles")
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	if err != nil {
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		return false, err
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	}
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	defer profiles.Close()
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	rbuff := bufio.NewReader(profiles)
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	for {
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		line, err := rbuff.ReadString('\n')
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		switch err {
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		case nil:
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			if strings.HasPrefix(line, profile+" (") {
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				return true, nil
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			}
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		case io.EOF:
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			return false, nil
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		default:
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			return false, err
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		}
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	}
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}
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// snapshotterOpts returns any Linux specific snapshotter options for the rootfs snapshot
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func snapshotterOpts(snapshotterName string, config *runtime.ContainerConfig) ([]snapshots.Opt, error) {
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	nsOpts := config.GetLinux().GetSecurityContext().GetNamespaceOptions()
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	return snapshotterRemapOpts(nsOpts)
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}
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