103 lines
4.8 KiB
Go
103 lines
4.8 KiB
Go
package client
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import (
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"github.com/jcmturner/gokrb5/v8/iana/flags"
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"github.com/jcmturner/gokrb5/v8/iana/nametype"
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"github.com/jcmturner/gokrb5/v8/krberror"
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"github.com/jcmturner/gokrb5/v8/messages"
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"github.com/jcmturner/gokrb5/v8/types"
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)
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// TGSREQGenerateAndExchange generates the TGS_REQ and performs a TGS exchange to retrieve a ticket to the specified SPN.
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func (cl *Client) TGSREQGenerateAndExchange(spn types.PrincipalName, kdcRealm string, tgt messages.Ticket, sessionKey types.EncryptionKey, renewal bool) (tgsReq messages.TGSReq, tgsRep messages.TGSRep, err error) {
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tgsReq, err = messages.NewTGSReq(cl.Credentials.CName(), kdcRealm, cl.Config, tgt, sessionKey, spn, renewal)
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if err != nil {
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return tgsReq, tgsRep, krberror.Errorf(err, krberror.KRBMsgError, "TGS Exchange Error: failed to generate a new TGS_REQ")
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}
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return cl.TGSExchange(tgsReq, kdcRealm, tgsRep.Ticket, sessionKey, 0)
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}
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// TGSExchange exchanges the provided TGS_REQ with the KDC to retrieve a TGS_REP.
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// Referrals are automatically handled.
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// The client's cache is updated with the ticket received.
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func (cl *Client) TGSExchange(tgsReq messages.TGSReq, kdcRealm string, tgt messages.Ticket, sessionKey types.EncryptionKey, referral int) (messages.TGSReq, messages.TGSRep, error) {
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var tgsRep messages.TGSRep
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b, err := tgsReq.Marshal()
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if err != nil {
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return tgsReq, tgsRep, krberror.Errorf(err, krberror.EncodingError, "TGS Exchange Error: failed to marshal TGS_REQ")
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}
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r, err := cl.sendToKDC(b, kdcRealm)
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if err != nil {
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if _, ok := err.(messages.KRBError); ok {
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return tgsReq, tgsRep, krberror.Errorf(err, krberror.KDCError, "TGS Exchange Error: kerberos error response from KDC when requesting for %s", tgsReq.ReqBody.SName.PrincipalNameString())
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}
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return tgsReq, tgsRep, krberror.Errorf(err, krberror.NetworkingError, "TGS Exchange Error: issue sending TGS_REQ to KDC")
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}
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err = tgsRep.Unmarshal(r)
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if err != nil {
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return tgsReq, tgsRep, krberror.Errorf(err, krberror.EncodingError, "TGS Exchange Error: failed to process the TGS_REP")
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}
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err = tgsRep.DecryptEncPart(sessionKey)
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if err != nil {
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return tgsReq, tgsRep, krberror.Errorf(err, krberror.EncodingError, "TGS Exchange Error: failed to process the TGS_REP")
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}
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if ok, err := tgsRep.Verify(cl.Config, tgsReq); !ok {
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return tgsReq, tgsRep, krberror.Errorf(err, krberror.EncodingError, "TGS Exchange Error: TGS_REP is not valid")
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}
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if tgsRep.Ticket.SName.NameString[0] == "krbtgt" && !tgsRep.Ticket.SName.Equal(tgsReq.ReqBody.SName) {
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if referral > 5 {
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return tgsReq, tgsRep, krberror.Errorf(err, krberror.KRBMsgError, "TGS Exchange Error: maximum number of referrals exceeded")
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}
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// Server referral https://tools.ietf.org/html/rfc6806.html#section-8
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// The TGS Rep contains a TGT for another domain as the service resides in that domain.
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cl.addSession(tgsRep.Ticket, tgsRep.DecryptedEncPart)
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realm := tgsRep.Ticket.SName.NameString[len(tgsRep.Ticket.SName.NameString)-1]
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referral++
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if types.IsFlagSet(&tgsReq.ReqBody.KDCOptions, flags.EncTktInSkey) && len(tgsReq.ReqBody.AdditionalTickets) > 0 {
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tgsReq, err = messages.NewUser2UserTGSReq(cl.Credentials.CName(), kdcRealm, cl.Config, tgt, sessionKey, tgsReq.ReqBody.SName, tgsReq.Renewal, tgsReq.ReqBody.AdditionalTickets[0])
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if err != nil {
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return tgsReq, tgsRep, err
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}
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}
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tgsReq, err = messages.NewTGSReq(cl.Credentials.CName(), realm, cl.Config, tgsRep.Ticket, tgsRep.DecryptedEncPart.Key, tgsReq.ReqBody.SName, tgsReq.Renewal)
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if err != nil {
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return tgsReq, tgsRep, err
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}
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return cl.TGSExchange(tgsReq, realm, tgsRep.Ticket, tgsRep.DecryptedEncPart.Key, referral)
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}
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cl.cache.addEntry(
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tgsRep.Ticket,
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tgsRep.DecryptedEncPart.AuthTime,
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tgsRep.DecryptedEncPart.StartTime,
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tgsRep.DecryptedEncPart.EndTime,
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tgsRep.DecryptedEncPart.RenewTill,
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tgsRep.DecryptedEncPart.Key,
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)
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cl.Log("ticket added to cache for %s (EndTime: %v)", tgsRep.Ticket.SName.PrincipalNameString(), tgsRep.DecryptedEncPart.EndTime)
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return tgsReq, tgsRep, err
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}
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// GetServiceTicket makes a request to get a service ticket for the SPN specified
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// SPN format: <SERVICE>/<FQDN> Eg. HTTP/www.example.com
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// The ticket will be added to the client's ticket cache
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func (cl *Client) GetServiceTicket(spn string) (messages.Ticket, types.EncryptionKey, error) {
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var tkt messages.Ticket
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var skey types.EncryptionKey
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if tkt, skey, ok := cl.GetCachedTicket(spn); ok {
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// Already a valid ticket in the cache
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return tkt, skey, nil
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}
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princ := types.NewPrincipalName(nametype.KRB_NT_PRINCIPAL, spn)
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realm := cl.Config.ResolveRealm(princ.NameString[len(princ.NameString)-1])
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tgt, skey, err := cl.sessionTGT(realm)
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if err != nil {
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return tkt, skey, err
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}
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_, tgsRep, err := cl.TGSREQGenerateAndExchange(princ, realm, tgt, skey, false)
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if err != nil {
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return tkt, skey, err
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}
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return tgsRep.Ticket, tgsRep.DecryptedEncPart.Key, nil
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}
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