| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 image |
| |
| import ( |
| "bytes" |
| "encoding/hex" |
| |
| "github.com/apache/mynewt-artifact/errors" |
| "github.com/apache/mynewt-artifact/manifest" |
| "github.com/apache/mynewt-artifact/sec" |
| ) |
| |
| func (img *Image) verifyHashDecrypted() error { |
| // Verify the hash. |
| haveHash, err := img.Hash() |
| if err != nil { |
| return err |
| } |
| |
| wantHash, err := img.CalcHash(nil) |
| if err != nil { |
| return err |
| } |
| |
| if !bytes.Equal(haveHash, wantHash) { |
| return errors.Errorf( |
| "image contains incorrect hash: have=%x want=%x", |
| haveHash, wantHash) |
| } |
| |
| return nil |
| } |
| |
| func (img *Image) verifyEncState() ([]byte, error) { |
| secret, err := img.CollectSecret() |
| if err != nil { |
| return nil, err |
| } |
| |
| if img.Header.Flags&IMAGE_F_ENCRYPTED == 0 { |
| if secret != nil { |
| return nil, errors.Errorf( |
| "encrypted flag set in image header, but no encryption TLV") |
| } |
| |
| return nil, nil |
| } else { |
| if secret == nil { |
| return nil, errors.Errorf( |
| "encryption TLV, but encrypted flag unset in image header") |
| } |
| |
| return secret, nil |
| } |
| } |
| |
| // VerifyStructure checks an image's structure for internal consistency. It |
| // returns an error if the image is incorrect. |
| func (img *Image) VerifyStructure() error { |
| // Verify that each TLV has a valid "type" field. |
| for _, t := range img.Tlvs { |
| if !ImageTlvTypeIsValid(t.Header.Type) { |
| return errors.Errorf( |
| "image contains TLV with invalid `type` field: %d", |
| t.Header.Type) |
| } |
| } |
| |
| if _, err := img.verifyEncState(); err != nil { |
| return err |
| } |
| |
| return nil |
| } |
| |
| // VerifyHash calculates an image's hash and compares it to the image's SHA256 |
| // TLV. If the image is encrypted, this function temporarily decrypts it |
| // before calculating the hash. The returned int is the index of the key that |
| // was used to decrypt the image, or -1 if none. An error is returned if the |
| // hash is incorrect. |
| func (img *Image) VerifyHash(privEncKeys []sec.PrivEncKey) (int, error) { |
| secret, err := img.verifyEncState() |
| if err != nil { |
| return -1, err |
| } |
| |
| if secret == nil { |
| // Image not encrypted. |
| if err := img.verifyHashDecrypted(); err != nil { |
| return -1, err |
| } |
| |
| return -1, nil |
| } |
| |
| // Image is encrypted. |
| if len(privEncKeys) == 0 { |
| return -1, errors.Errorf( |
| "attempt to verify hash of encrypted image: no keys provided") |
| } |
| |
| // We don't know which key the image is encrypted with. For each key, |
| // decrypt and then check the hash. |
| var hashErr error |
| for i, key := range privEncKeys { |
| dec, err := Decrypt(*img, key) |
| if err != nil { |
| hashErr = err |
| } else { |
| hashErr = dec.verifyHashDecrypted() |
| if hashErr == nil { |
| return i, nil |
| } |
| } |
| } |
| |
| return -1, hashErr |
| } |
| |
| // VerifySigs checks an image's attached signatures against the provided set of |
| // keys. It succeeds if the image has no signatures or if any signature can be |
| // verified. The returned int is the index of the key that was used to verify |
| // a signature, or -1 if none. An error is returned if there is at least one |
| // signature and they all fail the check. |
| func (img *Image) VerifySigs(keys []sec.PubSignKey) (int, error) { |
| sigs, err := img.CollectSigs() |
| if err != nil { |
| return -1, err |
| } |
| |
| if len(sigs) == 0 { |
| return -1, nil |
| } |
| |
| hash, err := img.Hash() |
| if err != nil { |
| return -1, err |
| } |
| |
| for keyIdx, k := range keys { |
| sigIdx, err := sec.VerifySigs(k, sigs, hash) |
| if err != nil { |
| return -1, err |
| } |
| |
| if sigIdx != -1 { |
| return keyIdx, nil |
| } |
| } |
| |
| return -1, errors.Errorf("image signatures do not match provided keys") |
| } |
| |
| // VerifyManifest compares an image's structure to its manifest. It returns |
| // an error if the image doesn't match the manifest. |
| func (img *Image) VerifyManifest(man manifest.Manifest) error { |
| ver, err := ParseVersion(man.Version) |
| if err != nil { |
| return errors.Wrapf(err, "manifest contains invalid `version` field") |
| } |
| |
| if ver.Major != img.Header.Vers.Major || |
| ver.Minor != img.Header.Vers.Minor || |
| ver.Rev != img.Header.Vers.Rev || |
| ver.BuildNum != img.Header.Vers.BuildNum { |
| |
| return errors.Errorf( |
| "manifest version different from image header: man=%s img=%s", |
| ver.String(), img.Header.Vers.String()) |
| } |
| |
| var imgHash string |
| if hash, err := img.Hash(); err == nil { |
| imgHash = hex.EncodeToString(hash) |
| } |
| |
| // A manifest contains two image hashes: `id` and `image_hash`. Check |
| // both. |
| |
| checkHash := func(manHash string) error { |
| if imgHash != manHash { |
| return errors.Errorf( |
| "manifest image hash different from image TLV: man=%s img=%s", |
| manHash, imgHash) |
| } |
| return nil |
| } |
| |
| if err := checkHash(man.BuildID); err != nil { |
| return err |
| } |
| if err := checkHash(man.ImageHash); err != nil { |
| return err |
| } |
| |
| return nil |
| } |