- if (gss_decrypt_xdr_buf(kctx->enc, buf, crypt_offset))
- return GSS_S_DEFECTIVE_TOKEN;
+
+ /*
+ * Need plaintext seqnum to derive encryption key for arcfour-hmac
+ */
+ if (krb5_get_seq_num(kctx, ptr + GSS_KRB5_TOK_HDR_LEN,
+ ptr + 8, &direction, &seqnum))
+ return GSS_S_BAD_SIG;
+
+ if ((kctx->initiate && direction != 0xff) ||
+ (!kctx->initiate && direction != 0))
+ return GSS_S_BAD_SIG;
+
+ if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC) {
+ struct crypto_blkcipher *cipher;
+ int err;
+
+ cipher = crypto_alloc_blkcipher(kctx->gk5e->encrypt_name, 0,
+ CRYPTO_ALG_ASYNC);
+ if (IS_ERR(cipher))
+ return GSS_S_FAILURE;
+
+ krb5_rc4_setup_enc_key(kctx, cipher, seqnum);
+
+ err = gss_decrypt_xdr_buf(cipher, buf, crypt_offset);
+ crypto_free_blkcipher(cipher);
+ if (err)
+ return GSS_S_DEFECTIVE_TOKEN;
+ } else {
+ if (gss_decrypt_xdr_buf(kctx->enc, buf, crypt_offset))
+ return GSS_S_DEFECTIVE_TOKEN;
+ }