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Authentication processor 3/4 - Add implementation
Signed-off-by: Juraci Paixão Kröhling <juraci@kroehling.de>
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// Copyright The OpenTelemetry Authors | ||
// | ||
// Licensed 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. | ||
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package auth | ||
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import ( | ||
"context" | ||
"crypto/tls" | ||
"crypto/x509" | ||
"encoding/pem" | ||
"errors" | ||
"fmt" | ||
"io/ioutil" | ||
"net" | ||
"net/http" | ||
"strings" | ||
"time" | ||
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"github.com/coreos/go-oidc" | ||
"google.golang.org/grpc" | ||
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"go.opentelemetry.io/collector/config/configauth" | ||
) | ||
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type oidcAuthenticator struct { | ||
attribute string | ||
config configauth.OIDC | ||
provider *oidc.Provider | ||
verifier *oidc.IDTokenVerifier | ||
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unaryInterceptor unaryInterceptorFunc | ||
streamInterceptor streamInterceptorFunc | ||
} | ||
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var ( | ||
_ Authenticator = (*oidcAuthenticator)(nil) | ||
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errNoClientIDProvided = errors.New("no ClientID provided for the OIDC configuration") | ||
errNoIssuerURL = errors.New("no IssuerURL provided for the OIDC configuration") | ||
errInvalidAuthenticationHeaderFormat = errors.New("invalid authorization header format") | ||
errFailedToObtainClaimsFromToken = errors.New("failed to get the subject from the token issued by the OIDC provider") | ||
errClaimNotFound = errors.New("username claim from the OIDC configuration not found on the token returned by the OIDC provider") | ||
errUsernameNotString = errors.New("the username returned by the OIDC provider isn't a regular string") | ||
errGroupsClaimNotFound = errors.New("groups claim from the OIDC configuration not found on the token returned by the OIDC provider") | ||
errNotAuthenticated = errors.New("authentication didn't succeed") | ||
) | ||
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func newOIDCAuthenticator(cfg configauth.Authentication) (*oidcAuthenticator, error) { | ||
if cfg.OIDC.Audience == "" { | ||
return nil, errNoClientIDProvided | ||
} | ||
if cfg.OIDC.IssuerURL == "" { | ||
return nil, errNoIssuerURL | ||
} | ||
if cfg.Attribute == "" { | ||
cfg.Attribute = defaultAttribute | ||
} | ||
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return &oidcAuthenticator{ | ||
attribute: cfg.Attribute, | ||
config: *cfg.OIDC, | ||
unaryInterceptor: defaultUnaryInterceptor, | ||
streamInterceptor: defaultStreamInterceptor, | ||
}, nil | ||
} | ||
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func (o *oidcAuthenticator) Authenticate(ctx context.Context, headers map[string][]string) (context.Context, error) { | ||
authHeaders := headers[o.attribute] | ||
if len(authHeaders) == 0 { | ||
return ctx, errNotAuthenticated | ||
} | ||
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// we only use the first header, if multiple values exist | ||
parts := strings.Split(authHeaders[0], " ") | ||
if len(parts) != 2 { | ||
return ctx, errInvalidAuthenticationHeaderFormat | ||
} | ||
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idToken, err := o.verifier.Verify(ctx, parts[1]) | ||
if err != nil { | ||
return ctx, fmt.Errorf("failed to verify token: %w", err) | ||
} | ||
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claims := map[string]interface{}{} | ||
if err = idToken.Claims(&claims); err != nil { | ||
// currently, this isn't a valid condition, the Verify call a few lines above | ||
// will already attempt to parse the payload as a json and set it as the claims | ||
// for the token. As we are using a map to hold the claims, there's no way to fail | ||
// to read the claims. It could fail if we were using a custom struct. Instead of | ||
// swalling the error, it's better to make this future-proof, in case the underlying | ||
// code changes | ||
return ctx, errFailedToObtainClaimsFromToken | ||
} | ||
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sub, err := getSubjectFromClaims(claims, o.config.UsernameClaim, idToken.Subject) | ||
if err != nil { | ||
return ctx, fmt.Errorf("failed to get subject from claims in the token: %w", err) | ||
} | ||
ctx = context.WithValue(ctx, subjectKey, sub) | ||
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gr, err := getGroupsFromClaims(claims, o.config.GroupsClaim) | ||
if err != nil { | ||
return ctx, fmt.Errorf("failed to get groups from claims in the token: %w", err) | ||
} | ||
ctx = context.WithValue(ctx, groupsKey, gr) | ||
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return ctx, nil | ||
} | ||
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func (o *oidcAuthenticator) Start(context.Context) error { | ||
provider, err := getProviderForConfig(o.config) | ||
if err != nil { | ||
return fmt.Errorf("failed to get configuration from the auth server: %w", err) | ||
} | ||
o.provider = provider | ||
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o.verifier = o.provider.Verifier(&oidc.Config{ | ||
ClientID: o.config.Audience, | ||
}) | ||
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return nil | ||
} | ||
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func (o *oidcAuthenticator) Close() error { | ||
// no-op at the moment | ||
// once we implement caching of the tokens we might need this | ||
return nil | ||
} | ||
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func (o *oidcAuthenticator) UnaryInterceptor(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) { | ||
return o.unaryInterceptor(ctx, req, info, handler, o.Authenticate) | ||
} | ||
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func (o *oidcAuthenticator) StreamInterceptor(srv interface{}, str grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error { | ||
return o.streamInterceptor(srv, str, info, handler, o.Authenticate) | ||
} | ||
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func getSubjectFromClaims(claims map[string]interface{}, usernameClaim string, fallback string) (string, error) { | ||
if len(usernameClaim) > 0 { | ||
username, found := claims[usernameClaim] | ||
if !found { | ||
return "", errClaimNotFound | ||
} | ||
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sUsername, ok := username.(string) | ||
if !ok { | ||
return "", errUsernameNotString | ||
} | ||
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return sUsername, nil | ||
} | ||
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return fallback, nil | ||
} | ||
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func getGroupsFromClaims(claims map[string]interface{}, groupsClaim string) ([]string, error) { | ||
if len(groupsClaim) > 0 { | ||
var groups []string | ||
rawGroup, ok := claims[groupsClaim] | ||
if !ok { | ||
return nil, errGroupsClaimNotFound | ||
} | ||
switch v := rawGroup.(type) { | ||
case string: | ||
groups = append(groups, v) | ||
case []string: | ||
groups = v | ||
case []interface{}: | ||
groups = make([]string, 0, len(v)) | ||
for i := range v { | ||
groups = append(groups, fmt.Sprintf("%v", v[i])) | ||
} | ||
} | ||
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return groups, nil | ||
} | ||
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return []string{}, nil | ||
} | ||
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func getProviderForConfig(config configauth.OIDC) (*oidc.Provider, error) { | ||
t := &http.Transport{ | ||
Proxy: http.ProxyFromEnvironment, | ||
DialContext: (&net.Dialer{ | ||
Timeout: 5 * time.Second, | ||
KeepAlive: 10 * time.Second, | ||
DualStack: true, | ||
}).DialContext, | ||
ForceAttemptHTTP2: true, | ||
MaxIdleConns: 100, | ||
IdleConnTimeout: 90 * time.Second, | ||
TLSHandshakeTimeout: 5 * time.Second, | ||
ExpectContinueTimeout: 1 * time.Second, | ||
} | ||
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cert, err := getIssuerCACertFromPath(config.IssuerCAPath) | ||
if err != nil { | ||
return nil, err // the errors from this path have enough context already | ||
} | ||
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if cert != nil { | ||
t.TLSClientConfig = &tls.Config{ | ||
RootCAs: x509.NewCertPool(), | ||
} | ||
t.TLSClientConfig.RootCAs.AddCert(cert) | ||
} | ||
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client := &http.Client{ | ||
Timeout: 5 * time.Second, | ||
Transport: t, | ||
} | ||
oidcContext := oidc.ClientContext(context.Background(), client) | ||
return oidc.NewProvider(oidcContext, config.IssuerURL) | ||
} | ||
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func getIssuerCACertFromPath(path string) (*x509.Certificate, error) { | ||
if path == "" { | ||
return nil, nil | ||
} | ||
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rawCA, err := ioutil.ReadFile(path) | ||
if err != nil { | ||
return nil, fmt.Errorf("could not read the CA file %q: %w", path, err) | ||
} | ||
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if len(rawCA) == 0 { | ||
return nil, fmt.Errorf("could not read the CA file %q: empty file", path) | ||
} | ||
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block, _ := pem.Decode(rawCA) | ||
if block == nil { | ||
return nil, fmt.Errorf("cannot decode the contents of the CA file %q: %w", path, err) | ||
} | ||
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return x509.ParseCertificate(block.Bytes) | ||
} |
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