github.com/blixtra/rkt@v0.8.1-0.20160204105720-ab0d1add1a43/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/coreos/rkt/pkg/keystore"
    23  	"github.com/hashicorp/errwrap"
    24  
    25  	"github.com/appc/spec/aci"
    26  	"github.com/appc/spec/schema"
    27  	"golang.org/x/crypto/openpgp"
    28  	pgperrors "golang.org/x/crypto/openpgp/errors"
    29  )
    30  
    31  // validator is a general image checker
    32  type validator struct {
    33  	image    io.ReadSeeker
    34  	manifest *schema.ImageManifest
    35  }
    36  
    37  // newValidator returns a validator instance if passed image is indeed
    38  // an ACI.
    39  func newValidator(image io.ReadSeeker) (*validator, error) {
    40  	manifest, err := aci.ManifestFromImage(image)
    41  	if err != nil {
    42  		return nil, err
    43  	}
    44  	v := &validator{
    45  		image:    image,
    46  		manifest: manifest,
    47  	}
    48  	return v, nil
    49  }
    50  
    51  // GetImageName returns image name as it is in the image manifest.
    52  func (v *validator) GetImageName() string {
    53  	return v.manifest.Name.String()
    54  }
    55  
    56  // ValidateName checks if desired image name is actually the same as
    57  // the one in the image manifest.
    58  func (v *validator) ValidateName(imageName string) error {
    59  	name := v.GetImageName()
    60  	if name != imageName {
    61  		return fmt.Errorf("error when reading the app name: %q expected but %q found",
    62  			imageName, name)
    63  	}
    64  	return nil
    65  }
    66  
    67  // ValidateWithSignature verifies the image against a given signature
    68  // file.
    69  func (v *validator) ValidateWithSignature(ks *keystore.Keystore, sig io.ReadSeeker) (*openpgp.Entity, error) {
    70  	if ks == nil {
    71  		return nil, nil
    72  	}
    73  	if _, err := v.image.Seek(0, 0); err != nil {
    74  		return nil, errwrap.Wrap(errors.New("error seeking ACI file"), err)
    75  	}
    76  	if _, err := sig.Seek(0, 0); err != nil {
    77  		return nil, errwrap.Wrap(errors.New("error seeking signature file"), err)
    78  	}
    79  	entity, err := ks.CheckSignature(v.GetImageName(), v.image, sig)
    80  	if err == pgperrors.ErrUnknownIssuer {
    81  		log.Print("If you expected the signing key to change, try running:")
    82  		log.Print("    rkt trust --prefix <image>")
    83  	}
    84  	if err != nil {
    85  		return nil, err
    86  	}
    87  	return entity, nil
    88  }