github.com/coreos/rocket@v1.30.1-0.20200224141603-171c416fac02/rkt/image/validator.go (about)

     1  // Copyright 2015 The rkt Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package image
    16  
    17  import (
    18  	"errors"
    19  	"fmt"
    20  	"io"
    21  
    22  	"github.com/hashicorp/errwrap"
    23  	"github.com/rkt/rkt/pkg/keystore"
    24  
    25  	"github.com/appc/spec/aci"
    26  	"github.com/appc/spec/schema"
    27  	"github.com/appc/spec/schema/types"
    28  	"golang.org/x/crypto/openpgp"
    29  	pgperrors "golang.org/x/crypto/openpgp/errors"
    30  )
    31  
    32  // validator is a general image checker
    33  type validator struct {
    34  	image    io.ReadSeeker
    35  	manifest *schema.ImageManifest
    36  }
    37  
    38  // newValidator returns a validator instance if passed image is indeed
    39  // an ACI.
    40  func newValidator(image io.ReadSeeker) (*validator, error) {
    41  	manifest, err := aci.ManifestFromImage(image)
    42  	if err != nil {
    43  		return nil, err
    44  	}
    45  	v := &validator{
    46  		image:    image,
    47  		manifest: manifest,
    48  	}
    49  	return v, nil
    50  }
    51  
    52  // ImageName returns image name as it is in the image manifest.
    53  func (v *validator) ImageName() string {
    54  	return v.manifest.Name.String()
    55  }
    56  
    57  // ValidateName checks if desired image name is actually the same as
    58  // the one in the image manifest.
    59  func (v *validator) ValidateName(imageName string) error {
    60  	name := v.ImageName()
    61  	if name != imageName {
    62  		return fmt.Errorf("error when reading the app name: %q expected but %q found",
    63  			imageName, name)
    64  	}
    65  	return nil
    66  }
    67  
    68  // ValidateLabels checks if desired image labels are actually the same as
    69  // the ones in the image manifest.
    70  func (v *validator) ValidateLabels(labels map[types.ACIdentifier]string) error {
    71  	for n, rv := range labels {
    72  		if av, ok := v.manifest.GetLabel(n.String()); ok {
    73  			if rv != av {
    74  				return fmt.Errorf("requested value for label %q: %q differs from fetched aci label value: %q", n, rv, av)
    75  			}
    76  		} else {
    77  			return fmt.Errorf("requested label %q not provided by the image manifest", n)
    78  		}
    79  	}
    80  	return nil
    81  }
    82  
    83  // ValidateWithSignature verifies the image against a given signature
    84  // file.
    85  func (v *validator) ValidateWithSignature(ks *keystore.Keystore, sig io.ReadSeeker) (*openpgp.Entity, error) {
    86  	if ks == nil {
    87  		return nil, nil
    88  	}
    89  	if _, err := v.image.Seek(0, 0); err != nil {
    90  		return nil, errwrap.Wrap(errors.New("error seeking ACI file"), err)
    91  	}
    92  	if _, err := sig.Seek(0, 0); err != nil {
    93  		return nil, errwrap.Wrap(errors.New("error seeking signature file"), err)
    94  	}
    95  	entity, err := ks.CheckSignature(v.ImageName(), v.image, sig)
    96  	if err == pgperrors.ErrUnknownIssuer {
    97  		log.Print("If you expected the signing key to change, try running:")
    98  		log.Print("    rkt trust --prefix <image>")
    99  	}
   100  	if err != nil {
   101  		return nil, err
   102  	}
   103  	return entity, nil
   104  }