386 lines
10 KiB
Go
386 lines
10 KiB
Go
package transit
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import (
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"context"
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"crypto/hmac"
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"encoding/base64"
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"fmt"
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"strconv"
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"strings"
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"github.com/hashicorp/errwrap"
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"github.com/hashicorp/vault/sdk/framework"
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"github.com/hashicorp/vault/sdk/helper/keysutil"
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"github.com/hashicorp/vault/sdk/logical"
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"github.com/mitchellh/mapstructure"
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)
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// BatchRequestHMACItem represents a request item for batch processing.
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// A map type allows us to distinguish between empty and missing values.
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type batchRequestHMACItem map[string]string
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// batchResponseHMACItem represents a response item for batch processing
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type batchResponseHMACItem struct {
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// HMAC for the input present in the corresponding batch request item
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HMAC string `json:"hmac,omitempty" mapstructure:"hmac"`
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// Valid indicates whether signature matches the signature derived from the input string
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Valid bool `json:"valid,omitempty" mapstructure:"valid"`
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// Error, if set represents a failure encountered while encrypting a
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// corresponding batch request item
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Error string `json:"error,omitempty" mapstructure:"error"`
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// The return paths in some cases are (nil, err) and others
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// (logical.ErrorResponse(..),nil), and others (logical.ErrorResponse(..),err).
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// For batch processing to successfully mimic previous handling for simple 'input',
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// both output values are needed - though 'err' should never be serialized.
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err error
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}
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func (b *backend) pathHMAC() *framework.Path {
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return &framework.Path{
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Pattern: "hmac/" + framework.GenericNameRegex("name") + framework.OptionalParamRegex("urlalgorithm"),
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Fields: map[string]*framework.FieldSchema{
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"name": {
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Type: framework.TypeString,
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Description: "The key to use for the HMAC function",
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},
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"input": {
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Type: framework.TypeString,
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Description: "The base64-encoded input data",
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},
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"algorithm": {
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Type: framework.TypeString,
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Default: "sha2-256",
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Description: `Algorithm to use (POST body parameter). Valid values are:
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* sha2-224
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* sha2-256
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* sha2-384
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* sha2-512
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Defaults to "sha2-256".`,
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},
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"urlalgorithm": {
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Type: framework.TypeString,
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Description: `Algorithm to use (POST URL parameter)`,
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},
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"key_version": {
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Type: framework.TypeInt,
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Description: `The version of the key to use for generating the HMAC.
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Must be 0 (for latest) or a value greater than or equal
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to the min_encryption_version configured on the key.`,
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},
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},
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Callbacks: map[logical.Operation]framework.OperationFunc{
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logical.UpdateOperation: b.pathHMACWrite,
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},
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HelpSynopsis: pathHMACHelpSyn,
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HelpDescription: pathHMACHelpDesc,
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}
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}
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func (b *backend) pathHMACWrite(ctx context.Context, req *logical.Request, d *framework.FieldData) (*logical.Response, error) {
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name := d.Get("name").(string)
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ver := d.Get("key_version").(int)
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algorithm := d.Get("urlalgorithm").(string)
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if algorithm == "" {
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algorithm = d.Get("algorithm").(string)
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}
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// Get the policy
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p, _, err := b.lm.GetPolicy(ctx, keysutil.PolicyRequest{
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Storage: req.Storage,
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Name: name,
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}, b.GetRandomReader())
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if err != nil {
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return nil, err
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}
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if p == nil {
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return logical.ErrorResponse("encryption key not found"), logical.ErrInvalidRequest
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}
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if !b.System().CachingDisabled() {
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p.Lock(false)
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}
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switch {
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case ver == 0:
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// Allowed, will use latest; set explicitly here to ensure the string
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// is generated properly
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ver = p.LatestVersion
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case ver == p.LatestVersion:
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// Allowed
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case p.MinEncryptionVersion > 0 && ver < p.MinEncryptionVersion:
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p.Unlock()
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return logical.ErrorResponse("cannot generate HMAC: version is too old (disallowed by policy)"), logical.ErrInvalidRequest
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}
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key, err := p.HMACKey(ver)
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if err != nil {
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p.Unlock()
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return logical.ErrorResponse(err.Error()), logical.ErrInvalidRequest
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}
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if key == nil {
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p.Unlock()
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return nil, fmt.Errorf("HMAC key value could not be computed")
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}
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hashAlgorithm, ok := keysutil.HashTypeMap[algorithm]
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if !ok {
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p.Unlock()
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return logical.ErrorResponse("unsupported algorithm %q", hashAlgorithm), nil
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}
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hashAlg := keysutil.HashFuncMap[hashAlgorithm]
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batchInputRaw := d.Raw["batch_input"]
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var batchInputItems []batchRequestHMACItem
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if batchInputRaw != nil {
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err = mapstructure.Decode(batchInputRaw, &batchInputItems)
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if err != nil {
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p.Unlock()
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return nil, errwrap.Wrapf("failed to parse batch input: {{err}}", err)
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}
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if len(batchInputItems) == 0 {
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p.Unlock()
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return logical.ErrorResponse("missing batch input to process"), logical.ErrInvalidRequest
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}
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} else {
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valueRaw, ok := d.GetOk("input")
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if !ok {
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p.Unlock()
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return logical.ErrorResponse("missing input for HMAC"), logical.ErrInvalidRequest
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}
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batchInputItems = make([]batchRequestHMACItem, 1)
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batchInputItems[0] = batchRequestHMACItem{
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"input": valueRaw.(string),
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}
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}
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response := make([]batchResponseHMACItem, len(batchInputItems))
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for i, item := range batchInputItems {
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rawInput, ok := item["input"]
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if !ok {
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response[i].Error = "missing input for HMAC"
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response[i].err = logical.ErrInvalidRequest
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continue
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}
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input, err := base64.StdEncoding.DecodeString(rawInput)
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if err != nil {
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response[i].Error = fmt.Sprintf("unable to decode input as base64: %s", err)
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response[i].err = logical.ErrInvalidRequest
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continue
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}
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hf := hmac.New(hashAlg, key)
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hf.Write(input)
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retBytes := hf.Sum(nil)
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retStr := base64.StdEncoding.EncodeToString(retBytes)
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retStr = fmt.Sprintf("vault:v%s:%s", strconv.Itoa(ver), retStr)
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response[i].HMAC = retStr
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}
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p.Unlock()
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// Generate the response
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resp := &logical.Response{}
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if batchInputRaw != nil {
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resp.Data = map[string]interface{}{
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"batch_results": response,
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}
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} else {
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if response[0].Error != "" || response[0].err != nil {
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if response[0].Error != "" {
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return logical.ErrorResponse(response[0].Error), response[0].err
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} else {
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return nil, response[0].err
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}
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}
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resp.Data = map[string]interface{}{
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"hmac": response[0].HMAC,
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}
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}
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return resp, nil
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}
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func (b *backend) pathHMACVerify(ctx context.Context, req *logical.Request, d *framework.FieldData) (*logical.Response, error) {
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name := d.Get("name").(string)
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algorithm := d.Get("urlalgorithm").(string)
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if algorithm == "" {
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algorithm = d.Get("algorithm").(string)
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}
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// Get the policy
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p, _, err := b.lm.GetPolicy(ctx, keysutil.PolicyRequest{
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Storage: req.Storage,
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Name: name,
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}, b.GetRandomReader())
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if err != nil {
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return nil, err
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}
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if p == nil {
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return logical.ErrorResponse("encryption key not found"), logical.ErrInvalidRequest
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}
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if !b.System().CachingDisabled() {
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p.Lock(false)
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}
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hashAlgorithm, ok := keysutil.HashTypeMap[algorithm]
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if !ok {
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p.Unlock()
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return logical.ErrorResponse("unsupported algorithm %q", hashAlgorithm), nil
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}
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hashAlg := keysutil.HashFuncMap[hashAlgorithm]
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batchInputRaw := d.Raw["batch_input"]
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var batchInputItems []batchRequestHMACItem
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if batchInputRaw != nil {
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err := mapstructure.Decode(batchInputRaw, &batchInputItems)
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if err != nil {
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p.Unlock()
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return nil, errwrap.Wrapf("failed to parse batch input: {{err}}", err)
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}
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if len(batchInputItems) == 0 {
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p.Unlock()
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return logical.ErrorResponse("missing batch input to process"), logical.ErrInvalidRequest
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}
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} else {
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// use empty string if input is missing - not an error
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inputB64 := d.Get("input").(string)
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hmac := d.Get("hmac").(string)
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batchInputItems = make([]batchRequestHMACItem, 1)
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batchInputItems[0] = batchRequestHMACItem{
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"input": inputB64,
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"hmac": hmac,
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}
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}
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response := make([]batchResponseHMACItem, len(batchInputItems))
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for i, item := range batchInputItems {
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rawInput, ok := item["input"]
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if !ok {
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response[i].Error = "missing input"
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response[i].err = logical.ErrInvalidRequest
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continue
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}
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input, err := base64.StdEncoding.DecodeString(rawInput)
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if err != nil {
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response[i].Error = fmt.Sprintf("unable to decode input as base64: %s", err)
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response[i].err = logical.ErrInvalidRequest
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continue
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}
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verificationHMAC, ok := item["hmac"]
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if !ok {
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response[i].Error = "missing hmac"
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response[i].err = logical.ErrInvalidRequest
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continue
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}
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// Verify the prefix
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if !strings.HasPrefix(verificationHMAC, "vault:v") {
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response[i].Error = "invalid HMAC to verify: no prefix"
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response[i].err = logical.ErrInvalidRequest
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continue
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}
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splitVerificationHMAC := strings.SplitN(strings.TrimPrefix(verificationHMAC, "vault:v"), ":", 2)
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if len(splitVerificationHMAC) != 2 {
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response[i].Error = "invalid HMAC: wrong number of fields"
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response[i].err = logical.ErrInvalidRequest
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continue
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}
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ver, err := strconv.Atoi(splitVerificationHMAC[0])
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if err != nil {
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response[i].Error = "invalid HMAC: version number could not be decoded"
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response[i].err = logical.ErrInvalidRequest
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continue
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}
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verBytes, err := base64.StdEncoding.DecodeString(splitVerificationHMAC[1])
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if err != nil {
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response[i].Error = fmt.Sprintf("unable to decode verification HMAC as base64: %s", err)
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response[i].err = logical.ErrInvalidRequest
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continue
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}
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if ver > p.LatestVersion {
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response[i].Error = "invalid HMAC: version is too new"
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response[i].err = logical.ErrInvalidRequest
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continue
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}
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if p.MinDecryptionVersion > 0 && ver < p.MinDecryptionVersion {
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response[i].Error = "cannot verify HMAC: version is too old (disallowed by policy)"
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response[i].err = logical.ErrInvalidRequest
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continue
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}
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key, err := p.HMACKey(ver)
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if err != nil {
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response[i].Error = err.Error()
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response[i].err = logical.ErrInvalidRequest
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continue
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}
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if key == nil {
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response[i].Error = ""
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response[i].err = fmt.Errorf("HMAC key value could not be computed")
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continue
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}
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hf := hmac.New(hashAlg, key)
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hf.Write(input)
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retBytes := hf.Sum(nil)
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response[i].Valid = hmac.Equal(retBytes, verBytes)
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}
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p.Unlock()
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// Generate the response
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resp := &logical.Response{}
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if batchInputRaw != nil {
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resp.Data = map[string]interface{}{
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"batch_results": response,
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}
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} else {
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if response[0].Error != "" || response[0].err != nil {
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if response[0].Error != "" {
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return logical.ErrorResponse(response[0].Error), response[0].err
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} else {
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return nil, response[0].err
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}
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}
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resp.Data = map[string]interface{}{
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"valid": response[0].Valid,
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}
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}
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return resp, nil
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}
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const pathHMACHelpSyn = `Generate an HMAC for input data using the named key`
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const pathHMACHelpDesc = `
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Generates an HMAC sum of the given algorithm and key against the given input data.
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`
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