Author: abartlet Date: 2005-09-12 14:19:05 +0000 (Mon, 12 Sep 2005) New Revision: 10174
WebSVN: http://websvn.samba.org/cgi-bin/viewcvs.cgi?view=rev&root=samba&rev=10174 Log: This patch implements generic PAC verification, without assumptions about the size of the signature. In particular, this works with AES, which was previously broken Samba4/Samba4. Reviewed by metze (and thanks for help with the previous IDL commit). Modified: branches/SAMBA_4_0/source/auth/kerberos/kerberos_pac.c Changeset: Modified: branches/SAMBA_4_0/source/auth/kerberos/kerberos_pac.c =================================================================== --- branches/SAMBA_4_0/source/auth/kerberos/kerberos_pac.c 2005-09-12 13:52:15 UTC (rev 10173) +++ branches/SAMBA_4_0/source/auth/kerberos/kerberos_pac.c 2005-09-12 14:19:05 UTC (rev 10174) @@ -78,38 +78,70 @@ { krb5_error_code ret; NTSTATUS status; - struct PAC_SIGNATURE_DATA srv_sig; struct PAC_SIGNATURE_DATA *srv_sig_ptr = NULL; - struct PAC_SIGNATURE_DATA kdc_sig; struct PAC_SIGNATURE_DATA *kdc_sig_ptr = NULL; + struct PAC_SIGNATURE_DATA *srv_sig_wipe = NULL; + struct PAC_SIGNATURE_DATA *kdc_sig_wipe = NULL; struct PAC_LOGON_INFO *logon_info = NULL; struct PAC_LOGON_NAME *logon_name = NULL; struct PAC_DATA *pac_data; + struct PAC_DATA_RAW *pac_data_raw; - DATA_BLOB modified_pac_blob = data_blob_talloc(mem_ctx, blob.data, blob.length); + DATA_BLOB *srv_sig_blob; + DATA_BLOB *kdc_sig_blob; + + DATA_BLOB modified_pac_blob; NTTIME tgs_authtime_nttime; krb5_principal client_principal_pac; int i; pac_data = talloc(mem_ctx, struct PAC_DATA); - if (!pac_data) { + pac_data_raw = talloc(mem_ctx, struct PAC_DATA_RAW); + kdc_sig_wipe = talloc(mem_ctx, struct PAC_SIGNATURE_DATA); + srv_sig_wipe = talloc(mem_ctx, struct PAC_SIGNATURE_DATA); + if (!pac_data_raw || !pac_data || !kdc_sig_wipe || !srv_sig_wipe) { return NT_STATUS_NO_MEMORY; } - status = ndr_pull_struct_blob(&blob, mem_ctx, pac_data, + status = ndr_pull_struct_blob(&blob, pac_data, pac_data, (ndr_pull_flags_fn_t)ndr_pull_PAC_DATA); if (!NT_STATUS_IS_OK(status)) { DEBUG(0,("can't parse the PAC\n")); return status; } - if (pac_data->num_buffers < 3) { + if (pac_data->num_buffers < 4) { /* we need logon_ingo, service_key and kdc_key */ - DEBUG(0,("less than 3 PAC buffers\n")); - return NT_STATUS_FOOBAR; + DEBUG(0,("less than 4 PAC buffers\n")); + return NT_STATUS_INVALID_PARAMETER; } + status = ndr_pull_struct_blob(&blob, pac_data_raw, pac_data_raw, + (ndr_pull_flags_fn_t)ndr_pull_PAC_DATA_RAW); + if (!NT_STATUS_IS_OK(status)) { + DEBUG(0,("can't parse the PAC\n")); + return status; + } + + if (pac_data_raw->num_buffers < 4) { + /* we need logon_ingo, service_key and kdc_key */ + DEBUG(0,("less than 4 PAC buffers\n")); + return NT_STATUS_INVALID_PARAMETER; + } + + if (pac_data->num_buffers != pac_data_raw->num_buffers) { + /* we need logon_ingo, service_key and kdc_key */ + DEBUG(0,("misparse! PAC_DATA has %d buffers while PAC_DATA_RAW has %d\n", + pac_data->num_buffers, pac_data_raw->num_buffers)); + return NT_STATUS_INVALID_PARAMETER; + } + for (i=0; i < pac_data->num_buffers; i++) { + if (pac_data->buffers[i].type != pac_data_raw->buffers[i].type) { + DEBUG(0,("misparse! PAC_DATA buffer %d has type %d while PAC_DATA_RAW has %d\n", + i, pac_data->buffers[i].type, pac_data->buffers[i].type)); + return NT_STATUS_INVALID_PARAMETER; + } switch (pac_data->buffers[i].type) { case PAC_TYPE_LOGON_INFO: if (!pac_data->buffers[i].info) { @@ -122,14 +154,14 @@ break; } srv_sig_ptr = &pac_data->buffers[i].info->srv_cksum; - srv_sig = pac_data->buffers[i].info->srv_cksum; + srv_sig_blob = &pac_data_raw->buffers[i].info->remaining; break; case PAC_TYPE_KDC_CHECKSUM: if (!pac_data->buffers[i].info) { break; } kdc_sig_ptr = &pac_data->buffers[i].info->kdc_cksum; - kdc_sig = pac_data->buffers[i].info->kdc_cksum; + kdc_sig_blob = &pac_data_raw->buffers[i].info->remaining; break; case PAC_TYPE_LOGON_NAME: logon_name = &pac_data->buffers[i].info->logon_name; @@ -141,29 +173,72 @@ if (!logon_info) { DEBUG(0,("PAC no logon_info\n")); - return NT_STATUS_FOOBAR; + return NT_STATUS_INVALID_PARAMETER; } - if (!srv_sig_ptr) { + if (!logon_name) { + DEBUG(0,("PAC no logon_name\n")); + return NT_STATUS_INVALID_PARAMETER; + } + + if (!srv_sig_ptr || !srv_sig_blob) { DEBUG(0,("PAC no srv_key\n")); - return NT_STATUS_FOOBAR; + return NT_STATUS_INVALID_PARAMETER; } - if (!kdc_sig_ptr) { + if (!kdc_sig_ptr || !kdc_sig_blob) { DEBUG(0,("PAC no kdc_key\n")); - return NT_STATUS_FOOBAR; + return NT_STATUS_INVALID_PARAMETER; } - memset(&modified_pac_blob.data[modified_pac_blob.length - 20], - '\0', 16); - memset(&modified_pac_blob.data[modified_pac_blob.length - 44], - '\0', 16); + /* Find and zero out the signatures, as required by the signing algorithm */ + /* We find the data blobs above, now we parse them to get at the exact portion we should zero */ + status = ndr_pull_struct_blob(kdc_sig_blob, kdc_sig_wipe, kdc_sig_wipe, + (ndr_pull_flags_fn_t)ndr_pull_PAC_SIGNATURE_DATA); + if (!NT_STATUS_IS_OK(status)) { + DEBUG(0,("can't parse the KDC signature\n")); + return status; + } + + status = ndr_pull_struct_blob(srv_sig_blob, srv_sig_wipe, srv_sig_wipe, + (ndr_pull_flags_fn_t)ndr_pull_PAC_SIGNATURE_DATA); + if (!NT_STATUS_IS_OK(status)) { + DEBUG(0,("can't parse the SRV signature\n")); + return status; + } + + /* Now zero the decoded structure */ + memset(kdc_sig_wipe->signature.data, '\0', kdc_sig_wipe->signature.length); + memset(srv_sig_wipe->signature.data, '\0', srv_sig_wipe->signature.length); + + /* and reencode, back into the same place it came from */ + status = ndr_push_struct_blob(kdc_sig_blob, pac_data_raw, kdc_sig_wipe, + (ndr_push_flags_fn_t)ndr_push_PAC_SIGNATURE_DATA); + if (!NT_STATUS_IS_OK(status)) { + DEBUG(0,("can't repack the KDC signature\n")); + return status; + } + status = ndr_push_struct_blob(srv_sig_blob, pac_data_raw, srv_sig_wipe, + (ndr_push_flags_fn_t)ndr_push_PAC_SIGNATURE_DATA); + if (!NT_STATUS_IS_OK(status)) { + DEBUG(0,("can't repack the SRV signature\n")); + return status; + } + + /* push out the whole structure, but now with zero'ed signatures */ + status = ndr_push_struct_blob(&modified_pac_blob, pac_data_raw, pac_data_raw, + (ndr_push_flags_fn_t)ndr_push_PAC_DATA_RAW); + if (!NT_STATUS_IS_OK(status)) { + DEBUG(0,("can't repack the RAW PAC\n")); + return status; + } + /* verify by service_key */ ret = check_pac_checksum(mem_ctx, - modified_pac_blob, &srv_sig, - context, - service_keyblock); + modified_pac_blob, srv_sig_ptr, + context, + service_keyblock); if (ret) { DEBUG(1, ("PAC Decode: Failed to verify the service signature: %s\n", smb_get_krb5_error_message(context, ret, mem_ctx))); @@ -172,7 +247,7 @@ if (krbtgt_keyblock) { ret = check_pac_checksum(mem_ctx, - srv_sig_ptr->signature, &kdc_sig, + srv_sig_ptr->signature, kdc_sig_ptr, context, krbtgt_keyblock); if (ret) { DEBUG(1, ("PAC Decode: Failed to verify the KDC signature: %s\n",
