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fix: validate AUSF confirmation link authority #228

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fix: validate AUSF confirmation link authority #228

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79 changes: 61 additions & 18 deletions internal/sbi/consumer/ausf_service.go
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,6 @@ import (
"sync"

amf_context "github.com/free5gc/amf/internal/context"
"github.com/free5gc/amf/internal/logger"
"github.com/free5gc/nas/nasType"
"github.com/free5gc/openapi"
Nausf_UEAuthentication "github.com/free5gc/openapi/ausf/UEAuthentication"
Expand Down Expand Up @@ -104,16 +103,9 @@ func (s *nausfService) SendUEAuthenticationAuthenticateRequest(ue *amf_context.A
func (s *nausfService) SendAuth5gAkaConfirmRequest(ue *amf_context.AmfUe, resStar string) (
*models.ConfirmationDataResponse, *models.ProblemDetails, error,
) {
var ausfUri string
var confirmUri *url.URL
var err error
if len(ue.AuthenticationCtx.Links["5g-aka"]) > 0 {
confirmUri, err = url.Parse(ue.AuthenticationCtx.Links["5g-aka"][0].Href)
}
confirmUri, ausfUri, err := resolveAUSFConfirmationURI(ue, "5g-aka")
if err != nil {
return nil, nil, err
} else {
ausfUri = fmt.Sprintf("%s://%s", confirmUri.Scheme, confirmUri.Host)
}

client := s.getUEAuthenticationClient(ausfUri)
Expand All @@ -126,7 +118,7 @@ func (s *nausfService) SendAuth5gAkaConfirmRequest(ue *amf_context.AmfUe, resSta
return nil, nil, err
}
// confirmUri.RequestURI() = "/nausf-auth/v1/ue-authentications/{authctxId}/5g-aka-confirmation"
// splituri = ["","nausf-auth","ue-authentications",{authctxId},"5g-aka-confirmation"]
// splituri = ["","nausf-auth","v1","ue-authentications",{authctxId},"5g-aka-confirmation"]
// authctxId = {authctxId}
splituri := strings.Split(confirmUri.RequestURI(), "/")
authctxId := ""
Expand Down Expand Up @@ -169,23 +161,18 @@ func (s *nausfService) SendAuth5gAkaConfirmRequest(ue *amf_context.AmfUe, resSta
func (s *nausfService) SendEapAuthConfirmRequest(ue *amf_context.AmfUe, eapMsg nasType.EAPMessage) (
response *models.EapSession, problemDetails *models.ProblemDetails, err1 error,
) {
var confirmUri *url.URL
var err error
if len(ue.AuthenticationCtx.Links["eap-session"]) > 0 {
confirmUri, err = url.Parse(ue.AuthenticationCtx.Links["eap-session"][0].Href)
}
confirmUri, ausfUri, err := resolveAUSFConfirmationURI(ue, "eap-session")
if err != nil {
logger.ConsumerLog.Errorf("url Parse failed: %+v", err)
return nil, nil, err
}
ausfUri := fmt.Sprintf("%s://%s", confirmUri.Scheme, confirmUri.Host)

client := s.getUEAuthenticationClient(ausfUri)
if client == nil {
return nil, nil, openapi.ReportError("ausf not found")
}

// confirmUri.RequestURI() = "/nausf-auth/v1/ue-authentications/{authctxId}/eap-session"
// splituri = ["","nausf-auth","ue-authentications",{authctxId},"eap-session"]
// splituri = ["","nausf-auth","v1","ue-authentications",{authctxId},"eap-session"]
// authctxId = {authctxId}
splituri := strings.Split(confirmUri.RequestURI(), "/")
authctxId := ""
Expand Down Expand Up @@ -232,3 +219,59 @@ func (s *nausfService) SendEapAuthConfirmRequest(ue *amf_context.AmfUe, eapMsg n

return response, problemDetails, err
}

func resolveAUSFConfirmationURI(ue *amf_context.AmfUe, linkName string) (*url.URL, string, error) {
if ue == nil {
return nil, "", fmt.Errorf("AmfUe is nil")
}
if ue.AuthenticationCtx == nil {
return nil, "", fmt.Errorf("ue authentication context is nil")
}

links := ue.AuthenticationCtx.Links[linkName]
if len(links) == 0 || strings.TrimSpace(links[0].Href) == "" {
return nil, "", fmt.Errorf("ausf confirmation link[%s] is empty", linkName)
}

confirmUri, err := url.Parse(links[0].Href)
if err != nil {
return nil, "", err
}
if validateErr := validateAUSFConfirmationURI(confirmUri); validateErr != nil {
return nil, "", validateErr
}

ausfUri, err := url.Parse(ue.AusfUri)
if err != nil {
return nil, "", err
}
if validateErr := validateAUSFConfirmationURI(ausfUri); validateErr != nil {
return nil, "", fmt.Errorf("invalid selected AUSF URI: %w", validateErr)
}

// TODO: If AMF stores all registered endpoints for the selected AUSF
// instance, validate against that trusted endpoint set instead.
if !strings.EqualFold(confirmUri.Scheme, ausfUri.Scheme) || !strings.EqualFold(confirmUri.Host, ausfUri.Host) {
return nil, "", fmt.Errorf("ausf confirmation link[%s] authority %q does not match selected AUSF %q",
linkName, confirmUri.Scheme+"://"+confirmUri.Host, ausfUri.Scheme+"://"+ausfUri.Host)
}

return confirmUri, strings.TrimRight(ue.AusfUri, "/"), nil
}

func validateAUSFConfirmationURI(uri *url.URL) error {
if uri == nil {
return fmt.Errorf("uri is nil")
}

switch strings.ToLower(uri.Scheme) {
case "http", "https":
default:
return fmt.Errorf("invalid ausf confirmation uri scheme %q", uri.Scheme)
}
if uri.Host == "" {
return fmt.Errorf("ausf confirmation uri host is empty")
}

return nil
}
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