Scott Baker | 8487c5d | 2019-10-18 12:49:46 -0700 | [diff] [blame^] | 1 | package pac |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "errors" |
| 6 | "fmt" |
| 7 | |
| 8 | "gopkg.in/jcmturner/gokrb5.v7/crypto" |
| 9 | "gopkg.in/jcmturner/gokrb5.v7/iana/keyusage" |
| 10 | "gopkg.in/jcmturner/gokrb5.v7/types" |
| 11 | "gopkg.in/jcmturner/rpc.v1/mstypes" |
| 12 | "gopkg.in/jcmturner/rpc.v1/ndr" |
| 13 | ) |
| 14 | |
| 15 | // https://msdn.microsoft.com/en-us/library/cc237931.aspx |
| 16 | |
| 17 | // CredentialsInfo implements https://msdn.microsoft.com/en-us/library/cc237953.aspx |
| 18 | type CredentialsInfo struct { |
| 19 | Version uint32 // A 32-bit unsigned integer in little-endian format that defines the version. MUST be 0x00000000. |
| 20 | EType uint32 |
| 21 | PACCredentialDataEncrypted []byte // Key usage number for encryption: KERB_NON_KERB_SALT (16) |
| 22 | PACCredentialData CredentialData |
| 23 | } |
| 24 | |
| 25 | // Unmarshal bytes into the CredentialsInfo struct |
| 26 | func (c *CredentialsInfo) Unmarshal(b []byte, k types.EncryptionKey) (err error) { |
| 27 | //The CredentialsInfo structure is a simple structure that is not NDR-encoded. |
| 28 | r := mstypes.NewReader(bytes.NewReader(b)) |
| 29 | |
| 30 | c.Version, err = r.Uint32() |
| 31 | if err != nil { |
| 32 | return |
| 33 | } |
| 34 | if c.Version != 0 { |
| 35 | err = errors.New("credentials info version is not zero") |
| 36 | return |
| 37 | } |
| 38 | c.EType, err = r.Uint32() |
| 39 | if err != nil { |
| 40 | return |
| 41 | } |
| 42 | c.PACCredentialDataEncrypted, err = r.ReadBytes(len(b) - 8) |
| 43 | |
| 44 | err = c.DecryptEncPart(k) |
| 45 | if err != nil { |
| 46 | err = fmt.Errorf("error decrypting PAC Credentials Data: %v", err) |
| 47 | return |
| 48 | } |
| 49 | return |
| 50 | } |
| 51 | |
| 52 | // DecryptEncPart decrypts the encrypted part of the CredentialsInfo. |
| 53 | func (c *CredentialsInfo) DecryptEncPart(k types.EncryptionKey) error { |
| 54 | if k.KeyType != int32(c.EType) { |
| 55 | return fmt.Errorf("key provided is not the correct type. Type needed: %d, type provided: %d", c.EType, k.KeyType) |
| 56 | } |
| 57 | pt, err := crypto.DecryptMessage(c.PACCredentialDataEncrypted, k, keyusage.KERB_NON_KERB_SALT) |
| 58 | if err != nil { |
| 59 | return err |
| 60 | } |
| 61 | err = c.PACCredentialData.Unmarshal(pt) |
| 62 | if err != nil { |
| 63 | return err |
| 64 | } |
| 65 | return nil |
| 66 | } |
| 67 | |
| 68 | // CredentialData implements https://msdn.microsoft.com/en-us/library/cc237952.aspx |
| 69 | // This structure is encrypted prior to being encoded in any other structures. |
| 70 | // Encryption is performed by first serializing the data structure via Network Data Representation (NDR) encoding, as specified in [MS-RPCE]. |
| 71 | // Once serialized, the data is encrypted using the key and cryptographic system selected through the AS protocol and the KRB_AS_REP message |
| 72 | // Fields (for capturing this information) and cryptographic parameters are specified in PAC_CREDENTIAL_INFO (section 2.6.1). |
| 73 | type CredentialData struct { |
| 74 | CredentialCount uint32 |
| 75 | Credentials []SECPKGSupplementalCred // Size is the value of CredentialCount |
| 76 | } |
| 77 | |
| 78 | // Unmarshal converts the bytes provided into a CredentialData type. |
| 79 | func (c *CredentialData) Unmarshal(b []byte) (err error) { |
| 80 | dec := ndr.NewDecoder(bytes.NewReader(b)) |
| 81 | err = dec.Decode(c) |
| 82 | if err != nil { |
| 83 | err = fmt.Errorf("error unmarshaling KerbValidationInfo: %v", err) |
| 84 | } |
| 85 | return |
| 86 | } |