certificates/authority/provisioner/collection.go

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package provisioner
import (
"crypto/sha1"
"crypto/x509"
"encoding/asn1"
"encoding/binary"
"encoding/hex"
"fmt"
"net/url"
"sort"
"strings"
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"sync"
"github.com/pkg/errors"
"github.com/smallstep/cli/jose"
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)
// DefaultProvisionersLimit is the default limit for listing provisioners.
const DefaultProvisionersLimit = 20
// DefaultProvisionersMax is the maximum limit for listing provisioners.
const DefaultProvisionersMax = 100
type uidProvisioner struct {
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provisioner Interface
uid string
}
type provisionerSlice []uidProvisioner
func (p provisionerSlice) Len() int { return len(p) }
func (p provisionerSlice) Less(i, j int) bool { return p[i].uid < p[j].uid }
func (p provisionerSlice) Swap(i, j int) { p[i], p[j] = p[j], p[i] }
// loadByTokenPayload is a payload used to extract the id used to load the
// provisioner.
type loadByTokenPayload struct {
jose.Claims
AuthorizedParty string `json:"azp"` // OIDC client id
TenantID string `json:"tid"` // Microsoft Azure tenant id
}
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// Collection is a memory map of provisioners.
type Collection struct {
byID *sync.Map
byKey *sync.Map
sorted provisionerSlice
audiences Audiences
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}
// NewCollection initializes a collection of provisioners. The given list of
// audiences are the audiences used by the JWT provisioner.
func NewCollection(audiences Audiences) *Collection {
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return &Collection{
byID: new(sync.Map),
byKey: new(sync.Map),
audiences: audiences,
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}
}
// Load a provisioner by the ID.
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func (c *Collection) Load(id string) (Interface, bool) {
return loadProvisioner(c.byID, id)
}
// LoadByToken parses the token claims and loads the provisioner associated.
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func (c *Collection) LoadByToken(token *jose.JSONWebToken, claims *jose.Claims) (Interface, bool) {
var audiences []string
// Get all audiences with the given fragment
fragment := extractFragment(claims.Audience)
if fragment == "" {
audiences = c.audiences.All()
} else {
audiences = c.audiences.WithFragment(fragment).All()
}
// match with server audiences
if matchesAudience(claims.Audience, audiences) {
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// Use fragment to get provisioner name (GCP, AWS)
if fragment != "" {
return c.Load(fragment)
}
// If matches with stored audiences it will be a JWT token (default), and
// the id would be <issuer>:<kid>.
return c.Load(claims.Issuer + ":" + token.Headers[0].KeyID)
}
// The ID will be just the clientID stored in azp, aud or tid.
var payload loadByTokenPayload
if err := token.UnsafeClaimsWithoutVerification(&payload); err != nil {
return nil, false
}
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// Audience is required
if len(payload.Audience) == 0 {
return nil, false
}
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// Try with azp (OIDC)
if len(payload.AuthorizedParty) > 0 {
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if p, ok := c.Load(payload.AuthorizedParty); ok {
return p, ok
}
}
// Try with tid (Azure)
if payload.TenantID != "" {
if p, ok := c.Load(payload.TenantID); ok {
return p, ok
}
}
// Fallback to aud
return c.Load(payload.Audience[0])
}
// LoadByCertificate looks for the provisioner extension and extracts the
// proper id to load the provisioner.
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func (c *Collection) LoadByCertificate(cert *x509.Certificate) (Interface, bool) {
for _, e := range cert.Extensions {
if e.Id.Equal(stepOIDProvisioner) {
var provisioner stepProvisionerASN1
if _, err := asn1.Unmarshal(e.Value, &provisioner); err != nil {
return nil, false
}
switch Type(provisioner.Type) {
case TypeJWK:
return c.Load(string(provisioner.Name) + ":" + string(provisioner.CredentialID))
case TypeAWS:
return c.Load("aws/" + string(provisioner.Name))
case TypeGCP:
return c.Load("gcp/" + string(provisioner.Name))
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default:
return c.Load(string(provisioner.CredentialID))
}
}
}
// Default to noop provisioner if an extension is not found. This allows to
// accept a renewal of a cert without the provisioner extension.
return &noop{}, true
}
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// LoadEncryptedKey returns an encrypted key by indexed by KeyID. At this moment
// only JWK encrypted keys are indexed by KeyID.
func (c *Collection) LoadEncryptedKey(keyID string) (string, bool) {
p, ok := loadProvisioner(c.byKey, keyID)
if !ok {
return "", false
}
_, key, ok := p.GetEncryptedKey()
return key, ok
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}
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// Store adds a provisioner to the collection and enforces the uniqueness of
// provisioner IDs.
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func (c *Collection) Store(p Interface) error {
// Store provisioner always in byID. ID must be unique.
if _, loaded := c.byID.LoadOrStore(p.GetID(), p); loaded == true {
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return errors.New("cannot add multiple provisioners with the same id")
}
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// Store provisioner in byKey if EncryptedKey is defined.
if kid, _, ok := p.GetEncryptedKey(); ok {
c.byKey.Store(kid, p)
}
// Store sorted provisioners.
// Use the first 4 bytes (32bit) of the sum to insert the order
// Using big endian format to get the strings sorted:
// 0x00000000, 0x00000001, 0x00000002, ...
bi := make([]byte, 4)
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sum := provisionerSum(p)
binary.BigEndian.PutUint32(bi, uint32(c.sorted.Len()))
sum[0], sum[1], sum[2], sum[3] = bi[0], bi[1], bi[2], bi[3]
c.sorted = append(c.sorted, uidProvisioner{
provisioner: p,
uid: hex.EncodeToString(sum),
})
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sort.Sort(c.sorted)
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return nil
}
// Find implements pagination on a list of sorted provisioners.
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func (c *Collection) Find(cursor string, limit int) (List, string) {
switch {
case limit <= 0:
limit = DefaultProvisionersLimit
case limit > DefaultProvisionersMax:
limit = DefaultProvisionersMax
}
n := c.sorted.Len()
cursor = fmt.Sprintf("%040s", cursor)
i := sort.Search(n, func(i int) bool { return c.sorted[i].uid >= cursor })
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slice := List{}
for ; i < n && len(slice) < limit; i++ {
slice = append(slice, c.sorted[i].provisioner)
}
if i < n {
return slice, strings.TrimLeft(c.sorted[i].uid, "0")
}
return slice, ""
}
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func loadProvisioner(m *sync.Map, key string) (Interface, bool) {
i, ok := m.Load(key)
if !ok {
return nil, false
}
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p, ok := i.(Interface)
if !ok {
return nil, false
}
return p, true
}
// provisionerSum returns the SHA1 of the provisioners ID. From this we will
// create the unique and sorted id.
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func provisionerSum(p Interface) []byte {
sum := sha1.Sum([]byte(p.GetID()))
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return sum[:]
}
// matchesAudience returns true if A and B share at least one element.
func matchesAudience(as, bs []string) bool {
if len(bs) == 0 || len(as) == 0 {
return false
}
for _, b := range bs {
for _, a := range as {
if b == a || stripPort(a) == stripPort(b) {
return true
}
}
}
return false
}
// stripPort attempts to strip the port from the given url. If parsing the url
// produces errors it will just return the passed argument.
func stripPort(rawurl string) string {
u, err := url.Parse(rawurl)
if err != nil {
return rawurl
}
u.Host = u.Hostname()
return u.String()
}
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// extractFragment extracts the first fragment of an audience url.
func extractFragment(audience []string) string {
for _, s := range audience {
if u, err := url.Parse(s); err == nil && u.Fragment != "" {
return u.Fragment
}
}
return ""
}