src

resolve_credentials.go (19777B)

---

 package config
 
 import (
 	"context"
 	"fmt"
 	"io/ioutil"
 	"net"
 	"net/url"
 	"os"
 	"time"
 
 	"github.com/aws/aws-sdk-go-v2/aws"
 	"github.com/aws/aws-sdk-go-v2/credentials"
 	"github.com/aws/aws-sdk-go-v2/credentials/ec2rolecreds"
 	"github.com/aws/aws-sdk-go-v2/credentials/endpointcreds"
 	"github.com/aws/aws-sdk-go-v2/credentials/processcreds"
 	"github.com/aws/aws-sdk-go-v2/credentials/ssocreds"
 	"github.com/aws/aws-sdk-go-v2/credentials/stscreds"
 	"github.com/aws/aws-sdk-go-v2/feature/ec2/imds"
 	"github.com/aws/aws-sdk-go-v2/service/sso"
 	"github.com/aws/aws-sdk-go-v2/service/ssooidc"
 	"github.com/aws/aws-sdk-go-v2/service/sts"
 )
 
 const (
 	// valid credential source values
 	credSourceEc2Metadata      = "Ec2InstanceMetadata"
 	credSourceEnvironment      = "Environment"
 	credSourceECSContainer     = "EcsContainer"
 	httpProviderAuthFileEnvVar = "AWS_CONTAINER_AUTHORIZATION_TOKEN_FILE"
 )
 
 // direct representation of the IPv4 address for the ECS container
 // "169.254.170.2"
 var ecsContainerIPv4 net.IP = []byte{
 	169, 254, 170, 2,
 }
 
 // direct representation of the IPv4 address for the EKS container
 // "169.254.170.23"
 var eksContainerIPv4 net.IP = []byte{
 	169, 254, 170, 23,
 }
 
 // direct representation of the IPv6 address for the EKS container
 // "fd00:ec2::23"
 var eksContainerIPv6 net.IP = []byte{
 	0xFD, 0, 0xE, 0xC2,
 	0, 0, 0, 0,
 	0, 0, 0, 0,
 	0, 0, 0, 0x23,
 }
 
 var (
 	ecsContainerEndpoint = "http://169.254.170.2" // not constant to allow for swapping during unit-testing
 )
 
 // resolveCredentials extracts a credential provider from slice of config
 // sources.
 //
 // If an explicit credential provider is not found the resolver will fallback
 // to resolving credentials by extracting a credential provider from EnvConfig
 // and SharedConfig.
 func resolveCredentials(ctx context.Context, cfg *aws.Config, configs configs) error {
 	found, err := resolveCredentialProvider(ctx, cfg, configs)
 	if found || err != nil {
 		return err
 	}
 
 	return resolveCredentialChain(ctx, cfg, configs)
 }
 
 // resolveCredentialProvider extracts the first instance of Credentials from the
 // config slices.
 //
 // The resolved CredentialProvider will be wrapped in a cache to ensure the
 // credentials are only refreshed when needed. This also protects the
 // credential provider to be used concurrently.
 //
 // Config providers used:
 // * credentialsProviderProvider
 func resolveCredentialProvider(ctx context.Context, cfg *aws.Config, configs configs) (bool, error) {
 	credProvider, found, err := getCredentialsProvider(ctx, configs)
 	if !found || err != nil {
 		return false, err
 	}
 
 	cfg.Credentials, err = wrapWithCredentialsCache(ctx, configs, credProvider)
 	if err != nil {
 		return false, err
 	}
 
 	return true, nil
 }
 
 // resolveCredentialChain resolves a credential provider chain using EnvConfig
 // and SharedConfig if present in the slice of provided configs.
 //
 // The resolved CredentialProvider will be wrapped in a cache to ensure the
 // credentials are only refreshed when needed. This also protects the
 // credential provider to be used concurrently.
 func resolveCredentialChain(ctx context.Context, cfg *aws.Config, configs configs) (err error) {
 	envConfig, sharedConfig, other := getAWSConfigSources(configs)
 
 	// When checking if a profile was specified programmatically we should only consider the "other"
 	// configuration sources that have been provided. This ensures we correctly honor the expected credential
 	// hierarchy.
 	_, sharedProfileSet, err := getSharedConfigProfile(ctx, other)
 	if err != nil {
 		return err
 	}
 
 	switch {
 	case sharedProfileSet:
 		ctx, err = resolveCredsFromProfile(ctx, cfg, envConfig, sharedConfig, other)
 	case envConfig.Credentials.HasKeys():
 		ctx = addCredentialSource(ctx, aws.CredentialSourceEnvVars)
 		cfg.Credentials = credentials.StaticCredentialsProvider{Value: envConfig.Credentials, Source: getCredentialSources(ctx)}
 	case len(envConfig.WebIdentityTokenFilePath) > 0:
 		ctx = addCredentialSource(ctx, aws.CredentialSourceEnvVarsSTSWebIDToken)
 		err = assumeWebIdentity(ctx, cfg, envConfig.WebIdentityTokenFilePath, envConfig.RoleARN, envConfig.RoleSessionName, configs)
 	default:
 		ctx, err = resolveCredsFromProfile(ctx, cfg, envConfig, sharedConfig, other)
 	}
 	if err != nil {
 		return err
 	}
 
 	// Wrap the resolved provider in a cache so the SDK will cache credentials.
 	cfg.Credentials, err = wrapWithCredentialsCache(ctx, configs, cfg.Credentials)
 	if err != nil {
 		return err
 	}
 
 	return nil
 }
 
 func resolveCredsFromProfile(ctx context.Context, cfg *aws.Config, envConfig *EnvConfig, sharedConfig *SharedConfig, configs configs) (ctx2 context.Context, err error) {
 	switch {
 	case sharedConfig.Source != nil:
 		ctx = addCredentialSource(ctx, aws.CredentialSourceProfileSourceProfile)
 		// Assume IAM role with credentials source from a different profile.
 		ctx, err = resolveCredsFromProfile(ctx, cfg, envConfig, sharedConfig.Source, configs)
 
 	case sharedConfig.Credentials.HasKeys():
 		// Static Credentials from Shared Config/Credentials file.
 		ctx = addCredentialSource(ctx, aws.CredentialSourceProfile)
 		cfg.Credentials = credentials.StaticCredentialsProvider{
 			Value:  sharedConfig.Credentials,
 			Source: getCredentialSources(ctx),
 		}
 
 	case len(sharedConfig.CredentialSource) != 0:
 		ctx = addCredentialSource(ctx, aws.CredentialSourceProfileNamedProvider)
 		ctx, err = resolveCredsFromSource(ctx, cfg, envConfig, sharedConfig, configs)
 
 	case len(sharedConfig.WebIdentityTokenFile) != 0:
 		// Credentials from Assume Web Identity token require an IAM Role, and
 		// that roll will be assumed. May be wrapped with another assume role
 		// via SourceProfile.
 		ctx = addCredentialSource(ctx, aws.CredentialSourceProfileSTSWebIDToken)
 		return ctx, assumeWebIdentity(ctx, cfg, sharedConfig.WebIdentityTokenFile, sharedConfig.RoleARN, sharedConfig.RoleSessionName, configs)
 
 	case sharedConfig.hasSSOConfiguration():
 		if sharedConfig.hasLegacySSOConfiguration() {
 			ctx = addCredentialSource(ctx, aws.CredentialSourceProfileSSOLegacy)
 			ctx = addCredentialSource(ctx, aws.CredentialSourceSSOLegacy)
 		} else {
 			ctx = addCredentialSource(ctx, aws.CredentialSourceSSO)
 		}
 		if sharedConfig.SSOSession != nil {
 			ctx = addCredentialSource(ctx, aws.CredentialSourceProfileSSO)
 		}
 		err = resolveSSOCredentials(ctx, cfg, sharedConfig, configs)
 
 	case len(sharedConfig.CredentialProcess) != 0:
 		// Get credentials from CredentialProcess
 		ctx = addCredentialSource(ctx, aws.CredentialSourceProfileProcess)
 		ctx = addCredentialSource(ctx, aws.CredentialSourceProcess)
 		err = processCredentials(ctx, cfg, sharedConfig, configs)
 
 	case len(envConfig.ContainerCredentialsRelativePath) != 0:
 		ctx = addCredentialSource(ctx, aws.CredentialSourceHTTP)
 		err = resolveHTTPCredProvider(ctx, cfg, ecsContainerURI(envConfig.ContainerCredentialsRelativePath), envConfig.ContainerAuthorizationToken, configs)
 
 	case len(envConfig.ContainerCredentialsEndpoint) != 0:
 		ctx = addCredentialSource(ctx, aws.CredentialSourceHTTP)
 		err = resolveLocalHTTPCredProvider(ctx, cfg, envConfig.ContainerCredentialsEndpoint, envConfig.ContainerAuthorizationToken, configs)
 
 	default:
 		ctx = addCredentialSource(ctx, aws.CredentialSourceIMDS)
 		err = resolveEC2RoleCredentials(ctx, cfg, configs)
 	}
 	if err != nil {
 		return ctx, err
 	}
 
 	if len(sharedConfig.RoleARN) > 0 {
 		return ctx, credsFromAssumeRole(ctx, cfg, sharedConfig, configs)
 	}
 
 	return ctx, nil
 }
 
 func resolveSSOCredentials(ctx context.Context, cfg *aws.Config, sharedConfig *SharedConfig, configs configs) error {
 	if err := sharedConfig.validateSSOConfiguration(); err != nil {
 		return err
 	}
 
 	var options []func(*ssocreds.Options)
 	v, found, err := getSSOProviderOptions(ctx, configs)
 	if err != nil {
 		return err
 	}
 	if found {
 		options = append(options, v)
 	}
 
 	cfgCopy := cfg.Copy()
 
 	options = append(options, func(o *ssocreds.Options) {
 		o.CredentialSources = getCredentialSources(ctx)
 	})
 
 	if sharedConfig.SSOSession != nil {
 		ssoTokenProviderOptionsFn, found, err := getSSOTokenProviderOptions(ctx, configs)
 		if err != nil {
 			return fmt.Errorf("failed to get SSOTokenProviderOptions from config sources, %w", err)
 		}
 		var optFns []func(*ssocreds.SSOTokenProviderOptions)
 		if found {
 			optFns = append(optFns, ssoTokenProviderOptionsFn)
 		}
 		cfgCopy.Region = sharedConfig.SSOSession.SSORegion
 		cachedPath, err := ssocreds.StandardCachedTokenFilepath(sharedConfig.SSOSession.Name)
 		if err != nil {
 			return err
 		}
 		oidcClient := ssooidc.NewFromConfig(cfgCopy)
 		tokenProvider := ssocreds.NewSSOTokenProvider(oidcClient, cachedPath, optFns...)
 		options = append(options, func(o *ssocreds.Options) {
 			o.SSOTokenProvider = tokenProvider
 			o.CachedTokenFilepath = cachedPath
 		})
 	} else {
 		cfgCopy.Region = sharedConfig.SSORegion
 	}
 
 	cfg.Credentials = ssocreds.New(sso.NewFromConfig(cfgCopy), sharedConfig.SSOAccountID, sharedConfig.SSORoleName, sharedConfig.SSOStartURL, options...)
 
 	return nil
 }
 
 func ecsContainerURI(path string) string {
 	return fmt.Sprintf("%s%s", ecsContainerEndpoint, path)
 }
 
 func processCredentials(ctx context.Context, cfg *aws.Config, sharedConfig *SharedConfig, configs configs) error {
 	var opts []func(*processcreds.Options)
 
 	options, found, err := getProcessCredentialOptions(ctx, configs)
 	if err != nil {
 		return err
 	}
 	if found {
 		opts = append(opts, options)
 	}
 
 	opts = append(opts, func(o *processcreds.Options) {
 		o.CredentialSources = getCredentialSources(ctx)
 	})
 
 	cfg.Credentials = processcreds.NewProvider(sharedConfig.CredentialProcess, opts...)
 
 	return nil
 }
 
 // isAllowedHost allows host to be loopback or known ECS/EKS container IPs
 //
 // host can either be an IP address OR an unresolved hostname - resolution will
 // be automatically performed in the latter case
 func isAllowedHost(host string) (bool, error) {
 	if ip := net.ParseIP(host); ip != nil {
 		return isIPAllowed(ip), nil
 	}
 
 	addrs, err := lookupHostFn(host)
 	if err != nil {
 		return false, err
 	}
 
 	for _, addr := range addrs {
 		if ip := net.ParseIP(addr); ip == nil || !isIPAllowed(ip) {
 			return false, nil
 		}
 	}
 
 	return true, nil
 }
 
 func isIPAllowed(ip net.IP) bool {
 	return ip.IsLoopback() ||
 		ip.Equal(ecsContainerIPv4) ||
 		ip.Equal(eksContainerIPv4) ||
 		ip.Equal(eksContainerIPv6)
 }
 
 func resolveLocalHTTPCredProvider(ctx context.Context, cfg *aws.Config, endpointURL, authToken string, configs configs) error {
 	var resolveErr error
 
 	parsed, err := url.Parse(endpointURL)
 	if err != nil {
 		resolveErr = fmt.Errorf("invalid URL, %w", err)
 	} else {
 		host := parsed.Hostname()
 		if len(host) == 0 {
 			resolveErr = fmt.Errorf("unable to parse host from local HTTP cred provider URL")
 		} else if parsed.Scheme == "http" {
 			if isAllowedHost, allowHostErr := isAllowedHost(host); allowHostErr != nil {
 				resolveErr = fmt.Errorf("failed to resolve host %q, %v", host, allowHostErr)
 			} else if !isAllowedHost {
 				resolveErr = fmt.Errorf("invalid endpoint host, %q, only loopback/ecs/eks hosts are allowed", host)
 			}
 		}
 	}
 
 	if resolveErr != nil {
 		return resolveErr
 	}
 
 	return resolveHTTPCredProvider(ctx, cfg, endpointURL, authToken, configs)
 }
 
 func resolveHTTPCredProvider(ctx context.Context, cfg *aws.Config, url, authToken string, configs configs) error {
 	optFns := []func(*endpointcreds.Options){
 		func(options *endpointcreds.Options) {
 			if len(authToken) != 0 {
 				options.AuthorizationToken = authToken
 			}
 			if authFilePath := os.Getenv(httpProviderAuthFileEnvVar); authFilePath != "" {
 				options.AuthorizationTokenProvider = endpointcreds.TokenProviderFunc(func() (string, error) {
 					var contents []byte
 					var err error
 					if contents, err = ioutil.ReadFile(authFilePath); err != nil {
 						return "", fmt.Errorf("failed to read authorization token from %v: %v", authFilePath, err)
 					}
 					return string(contents), nil
 				})
 			}
 			options.APIOptions = cfg.APIOptions
 			if cfg.Retryer != nil {
 				options.Retryer = cfg.Retryer()
 			}
 			options.CredentialSources = getCredentialSources(ctx)
 		},
 	}
 
 	optFn, found, err := getEndpointCredentialProviderOptions(ctx, configs)
 	if err != nil {
 		return err
 	}
 	if found {
 		optFns = append(optFns, optFn)
 	}
 
 	provider := endpointcreds.New(url, optFns...)
 
 	cfg.Credentials, err = wrapWithCredentialsCache(ctx, configs, provider, func(options *aws.CredentialsCacheOptions) {
 		options.ExpiryWindow = 5 * time.Minute
 	})
 	if err != nil {
 		return err
 	}
 
 	return nil
 }
 
 func resolveCredsFromSource(ctx context.Context, cfg *aws.Config, envConfig *EnvConfig, sharedCfg *SharedConfig, configs configs) (context.Context, error) {
 	switch sharedCfg.CredentialSource {
 	case credSourceEc2Metadata:
 		ctx = addCredentialSource(ctx, aws.CredentialSourceIMDS)
 		return ctx, resolveEC2RoleCredentials(ctx, cfg, configs)
 
 	case credSourceEnvironment:
 		ctx = addCredentialSource(ctx, aws.CredentialSourceHTTP)
 		cfg.Credentials = credentials.StaticCredentialsProvider{Value: envConfig.Credentials, Source: getCredentialSources(ctx)}
 
 	case credSourceECSContainer:
 		ctx = addCredentialSource(ctx, aws.CredentialSourceHTTP)
 		if len(envConfig.ContainerCredentialsRelativePath) != 0 {
 			return ctx, resolveHTTPCredProvider(ctx, cfg, ecsContainerURI(envConfig.ContainerCredentialsRelativePath), envConfig.ContainerAuthorizationToken, configs)
 		}
 		if len(envConfig.ContainerCredentialsEndpoint) != 0 {
 			return ctx, resolveLocalHTTPCredProvider(ctx, cfg, envConfig.ContainerCredentialsEndpoint, envConfig.ContainerAuthorizationToken, configs)
 		}
 		return ctx, fmt.Errorf("EcsContainer was specified as the credential_source, but neither 'AWS_CONTAINER_CREDENTIALS_RELATIVE_URI' or AWS_CONTAINER_CREDENTIALS_FULL_URI' was set")
 
 	default:
 		return ctx, fmt.Errorf("credential_source values must be EcsContainer, Ec2InstanceMetadata, or Environment")
 	}
 
 	return ctx, nil
 }
 
 func resolveEC2RoleCredentials(ctx context.Context, cfg *aws.Config, configs configs) error {
 	optFns := make([]func(*ec2rolecreds.Options), 0, 2)
 
 	optFn, found, err := getEC2RoleCredentialProviderOptions(ctx, configs)
 	if err != nil {
 		return err
 	}
 	if found {
 		optFns = append(optFns, optFn)
 	}
 
 	optFns = append(optFns, func(o *ec2rolecreds.Options) {
 		// Only define a client from config if not already defined.
 		if o.Client == nil {
 			o.Client = imds.NewFromConfig(*cfg)
 		}
 		o.CredentialSources = getCredentialSources(ctx)
 	})
 
 	provider := ec2rolecreds.New(optFns...)
 
 	cfg.Credentials, err = wrapWithCredentialsCache(ctx, configs, provider)
 	if err != nil {
 		return err
 	}
 	return nil
 }
 
 func getAWSConfigSources(cfgs configs) (*EnvConfig, *SharedConfig, configs) {
 	var (
 		envConfig    *EnvConfig
 		sharedConfig *SharedConfig
 		other        configs
 	)
 
 	for i := range cfgs {
 		switch c := cfgs[i].(type) {
 		case EnvConfig:
 			if envConfig == nil {
 				envConfig = &c
 			}
 		case *EnvConfig:
 			if envConfig == nil {
 				envConfig = c
 			}
 		case SharedConfig:
 			if sharedConfig == nil {
 				sharedConfig = &c
 			}
 		case *SharedConfig:
 			if envConfig == nil {
 				sharedConfig = c
 			}
 		default:
 			other = append(other, c)
 		}
 	}
 
 	if envConfig == nil {
 		envConfig = &EnvConfig{}
 	}
 
 	if sharedConfig == nil {
 		sharedConfig = &SharedConfig{}
 	}
 
 	return envConfig, sharedConfig, other
 }
 
 // AssumeRoleTokenProviderNotSetError is an error returned when creating a
 // session when the MFAToken option is not set when shared config is configured
 // load assume a role with an MFA token.
 type AssumeRoleTokenProviderNotSetError struct{}
 
 // Error is the error message
 func (e AssumeRoleTokenProviderNotSetError) Error() string {
 	return fmt.Sprintf("assume role with MFA enabled, but AssumeRoleTokenProvider session option not set.")
 }
 
 func assumeWebIdentity(ctx context.Context, cfg *aws.Config, filepath string, roleARN, sessionName string, configs configs) error {
 	if len(filepath) == 0 {
 		return fmt.Errorf("token file path is not set")
 	}
 
 	optFns := []func(*stscreds.WebIdentityRoleOptions){
 		func(options *stscreds.WebIdentityRoleOptions) {
 			options.RoleSessionName = sessionName
 		},
 	}
 
 	optFn, found, err := getWebIdentityCredentialProviderOptions(ctx, configs)
 	if err != nil {
 		return err
 	}
 
 	if found {
 		optFns = append(optFns, optFn)
 	}
 
 	opts := stscreds.WebIdentityRoleOptions{
 		RoleARN: roleARN,
 	}
 
 	optFns = append(optFns, func(options *stscreds.WebIdentityRoleOptions) {
 		options.CredentialSources = getCredentialSources(ctx)
 	})
 
 	for _, fn := range optFns {
 		fn(&opts)
 	}
 
 	if len(opts.RoleARN) == 0 {
 		return fmt.Errorf("role ARN is not set")
 	}
 
 	client := opts.Client
 	if client == nil {
 		client = sts.NewFromConfig(*cfg)
 	}
 
 	provider := stscreds.NewWebIdentityRoleProvider(client, roleARN, stscreds.IdentityTokenFile(filepath), optFns...)
 
 	cfg.Credentials = provider
 
 	return nil
 }
 
 func credsFromAssumeRole(ctx context.Context, cfg *aws.Config, sharedCfg *SharedConfig, configs configs) (err error) {
 	// resolve credentials early
 	credentialSources := getCredentialSources(ctx)
 	optFns := []func(*stscreds.AssumeRoleOptions){
 		func(options *stscreds.AssumeRoleOptions) {
 			options.RoleSessionName = sharedCfg.RoleSessionName
 			if sharedCfg.RoleDurationSeconds != nil {
 				if *sharedCfg.RoleDurationSeconds/time.Minute > 15 {
 					options.Duration = *sharedCfg.RoleDurationSeconds
 				}
 			}
 			// Assume role with external ID
 			if len(sharedCfg.ExternalID) > 0 {
 				options.ExternalID = aws.String(sharedCfg.ExternalID)
 			}
 
 			// Assume role with MFA
 			if len(sharedCfg.MFASerial) != 0 {
 				options.SerialNumber = aws.String(sharedCfg.MFASerial)
 			}
 
 			// add existing credential chain
 			options.CredentialSources = credentialSources
 		},
 	}
 
 	optFn, found, err := getAssumeRoleCredentialProviderOptions(ctx, configs)
 	if err != nil {
 		return err
 	}
 	if found {
 		optFns = append(optFns, optFn)
 	}
 
 	{
 		// Synthesize options early to validate configuration errors sooner to ensure a token provider
 		// is present if the SerialNumber was set.
 		var o stscreds.AssumeRoleOptions
 		for _, fn := range optFns {
 			fn(&o)
 		}
 		if o.TokenProvider == nil && o.SerialNumber != nil {
 			return AssumeRoleTokenProviderNotSetError{}
 		}
 	}
 	cfg.Credentials = stscreds.NewAssumeRoleProvider(sts.NewFromConfig(*cfg), sharedCfg.RoleARN, optFns...)
 
 	return nil
 }
 
 // wrapWithCredentialsCache will wrap provider with an aws.CredentialsCache
 // with the provided options if the provider is not already a
 // aws.CredentialsCache.
 func wrapWithCredentialsCache(
 	ctx context.Context,
 	cfgs configs,
 	provider aws.CredentialsProvider,
 	optFns ...func(options *aws.CredentialsCacheOptions),
 ) (aws.CredentialsProvider, error) {
 	_, ok := provider.(*aws.CredentialsCache)
 	if ok {
 		return provider, nil
 	}
 
 	credCacheOptions, optionsFound, err := getCredentialsCacheOptionsProvider(ctx, cfgs)
 	if err != nil {
 		return nil, err
 	}
 
 	// force allocation of a new slice if the additional options are
 	// needed, to prevent overwriting the passed in slice of options.
 	optFns = optFns[:len(optFns):len(optFns)]
 	if optionsFound {
 		optFns = append(optFns, credCacheOptions)
 	}
 
 	return aws.NewCredentialsCache(provider, optFns...), nil
 }
 
 // credentialSource stores the chain of providers that was used to create an instance of
 // a credentials provider on the context
 type credentialSource struct{}
 
 func addCredentialSource(ctx context.Context, source aws.CredentialSource) context.Context {
 	existing, ok := ctx.Value(credentialSource{}).([]aws.CredentialSource)
 	if !ok {
 		existing = []aws.CredentialSource{source}
 	} else {
 		existing = append(existing, source)
 	}
 	return context.WithValue(ctx, credentialSource{}, existing)
 }
 
 func getCredentialSources(ctx context.Context) []aws.CredentialSource {
 	return ctx.Value(credentialSource{}).([]aws.CredentialSource)
 }