{
struct db_context *db_sc = NULL;
char *fname = lpcfg_private_db_path(mem_ctx, lp_ctx, "schannel_store");
+ int hash_size, tdb_flags;
if (!fname) {
return NULL;
}
- db_sc = dbwrap_local_open(mem_ctx, lp_ctx, fname, 0,
- TDB_CLEAR_IF_FIRST|TDB_NOSYNC, O_RDWR|O_CREAT,
- 0600, 0);
+ hash_size = lpcfg_tdb_hash_size(lp_ctx, fname);
+ tdb_flags = lpcfg_tdb_flags(lp_ctx, TDB_CLEAR_IF_FIRST|TDB_NOSYNC);
+
+ db_sc = dbwrap_local_open(
+ mem_ctx,
+ fname,
+ hash_size,
+ tdb_flags,
+ O_RDWR|O_CREAT,
+ 0600,
+ DBWRAP_LOCK_ORDER_1,
+ DBWRAP_FLAG_NONE);
if (!db_sc) {
DEBUG(0,("open_schannel_session_store: Failed to open %s - %s\n",
char *name_upper;
NTSTATUS status;
+ if (strlen(creds->computer_name) > 15) {
+ /*
+ * We may want to check for a completely
+ * valid netbios name.
+ */
+ return STATUS_BUFFER_OVERFLOW;
+ }
+
name_upper = strupper_talloc(mem_ctx, creds->computer_name);
if (!name_upper) {
return NT_STATUS_NO_MEMORY;
db_sc = open_schannel_session_store(tmpctx, lp_ctx);
if (!db_sc) {
+ TALLOC_FREE(tmpctx);
return NT_STATUS_ACCESS_DENIED;
}
db_sc = open_schannel_session_store(tmpctx, lp_ctx);
if (!db_sc) {
- return NT_STATUS_ACCESS_DENIED;
+ status = NT_STATUS_ACCESS_DENIED;
+ goto fail;
}
status = schannel_store_session_key_tdb(db_sc, tmpctx, creds);
+fail:
talloc_free(tmpctx);
return status;
}
+
+/*
+ * Create a very lossy hash of the computer name.
+ *
+ * The idea here is to compress the computer name into small space so
+ * that malicious clients cannot fill the database with junk, as only a
+ * maximum of 16k of entries are possible.
+ *
+ * Collisions are certainly possible, and the design behaves in the
+ * same way as when the hostname is reused, but clients that use the
+ * same connection do not go via the cache, and the cache only needs
+ * to function between the ReqChallenge and ServerAuthenticate
+ * packets.
+ */
+static void hash_computer_name(const char *computer_name,
+ char keystr[16])
+{
+ unsigned int hash;
+ TDB_DATA computer_tdb_data = {
+ .dptr = (uint8_t *)discard_const_p(char, computer_name),
+ .dsize = strlen(computer_name)
+ };
+ hash = tdb_jenkins_hash(&computer_tdb_data);
+
+ /* we are using 14 bits of the digest to index our connections, so
+ that we use at most 16,384 buckets.*/
+ snprintf(keystr, 15, "CHALLENGE/%x%x", hash & 0xFF,
+ (hash & 0xFF00 >> 8) & 0x3f);
+ return;
+}
+
+
+static
+NTSTATUS schannel_store_challenge_tdb(struct db_context *db_sc,
+ TALLOC_CTX *mem_ctx,
+ const struct netr_Credential *client_challenge,
+ const struct netr_Credential *server_challenge,
+ const char *computer_name)
+{
+ enum ndr_err_code ndr_err;
+ DATA_BLOB blob;
+ TDB_DATA value;
+ char *name_upper = NULL;
+ NTSTATUS status;
+ char keystr[16] = { 0, };
+ struct netlogon_cache_entry cache_entry;
+
+ if (strlen(computer_name) > 255) {
+ /*
+ * We don't make this a limit at 15 chars as Samba has
+ * a test showing this can be longer :-(
+ */
+ return STATUS_BUFFER_OVERFLOW;
+ }
+
+ name_upper = strupper_talloc(mem_ctx, computer_name);
+ if (name_upper == NULL) {
+ return NT_STATUS_NO_MEMORY;
+ }
+
+ hash_computer_name(name_upper, keystr);
+
+ cache_entry.computer_name = name_upper;
+ cache_entry.client_challenge = *client_challenge;
+ cache_entry.server_challenge = *server_challenge;
+
+ ndr_err = ndr_push_struct_blob(&blob, mem_ctx, &cache_entry,
+ (ndr_push_flags_fn_t)ndr_push_netlogon_cache_entry);
+ if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+ return NT_STATUS_UNSUCCESSFUL;
+ }
+
+ value.dptr = blob.data;
+ value.dsize = blob.length;
+
+ status = dbwrap_store_bystring(db_sc, keystr, value, TDB_REPLACE);
+ if (!NT_STATUS_IS_OK(status)) {
+ DEBUG(0,("%s: failed to stored challenge info for '%s' "
+ "with key %s - %s\n",
+ __func__, cache_entry.computer_name, keystr,
+ nt_errstr(status)));
+ return status;
+ }
+
+ DEBUG(3,("%s: stored challenge info for '%s' with key %s\n",
+ __func__, cache_entry.computer_name, keystr));
+
+ if (DEBUGLEVEL >= 10) {
+ NDR_PRINT_DEBUG(netlogon_cache_entry, &cache_entry);
+ }
+
+ return NT_STATUS_OK;
+}
+
+/********************************************************************
+ Fetch a single challenge from the TDB.
+ ********************************************************************/
+
+static
+NTSTATUS schannel_fetch_challenge_tdb(struct db_context *db_sc,
+ TALLOC_CTX *mem_ctx,
+ struct netr_Credential *client_challenge,
+ struct netr_Credential *server_challenge,
+ const char *computer_name)
+{
+ NTSTATUS status;
+ TDB_DATA value;
+ enum ndr_err_code ndr_err;
+ DATA_BLOB blob;
+ char keystr[16] = { 0, };
+ struct netlogon_cache_entry cache_entry;
+ char *name_upper = NULL;
+
+ name_upper = strupper_talloc(mem_ctx, computer_name);
+ if (name_upper == NULL) {
+ return NT_STATUS_NO_MEMORY;
+ }
+
+ hash_computer_name(name_upper, keystr);
+
+ status = dbwrap_fetch_bystring(db_sc, mem_ctx, keystr, &value);
+ if (!NT_STATUS_IS_OK(status)) {
+ DEBUG(3,("%s: Failed to find entry for %s with key %s - %s\n",
+ __func__, name_upper, keystr, nt_errstr(status)));
+ goto done;
+ }
+
+ blob = data_blob_const(value.dptr, value.dsize);
+
+ ndr_err = ndr_pull_struct_blob_all(&blob, mem_ctx, &cache_entry,
+ (ndr_pull_flags_fn_t)ndr_pull_netlogon_cache_entry);
+ if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+ status = ndr_map_error2ntstatus(ndr_err);
+ DEBUG(3,("%s: Failed to parse entry for %s with key %s - %s\n",
+ __func__, name_upper, keystr, nt_errstr(status)));
+ goto done;
+ }
+
+ if (DEBUGLEVEL >= 10) {
+ NDR_PRINT_DEBUG(netlogon_cache_entry, &cache_entry);
+ }
+
+ if (strcmp(cache_entry.computer_name, name_upper) != 0) {
+ status = NT_STATUS_NOT_FOUND;
+
+ DEBUG(1, ("%s: HASH COLLISION with key %s ! "
+ "Wanted to fetch record for %s but got %s.",
+ __func__, keystr, name_upper,
+ cache_entry.computer_name));
+ } else {
+
+ DEBUG(3,("%s: restored key %s for %s\n",
+ __func__, keystr, cache_entry.computer_name));
+
+ *client_challenge = cache_entry.client_challenge;
+ *server_challenge = cache_entry.server_challenge;
+ }
+ done:
+
+ if (!NT_STATUS_IS_OK(status)) {
+ return status;
+ }
+
+ return NT_STATUS_OK;
+}
+
+/******************************************************************************
+ Wrapper around schannel_fetch_challenge_tdb()
+ Note we must be root here.
+
+*******************************************************************************/
+
+NTSTATUS schannel_get_challenge(struct loadparm_context *lp_ctx,
+ struct netr_Credential *client_challenge,
+ struct netr_Credential *server_challenge,
+ const char *computer_name)
+{
+ TALLOC_CTX *frame = talloc_stackframe();
+ struct db_context *db_sc;
+ NTSTATUS status;
+
+ db_sc = open_schannel_session_store(frame, lp_ctx);
+ if (!db_sc) {
+ TALLOC_FREE(frame);
+ return NT_STATUS_ACCESS_DENIED;
+ }
+
+ status = schannel_fetch_challenge_tdb(db_sc, frame,
+ client_challenge,
+ server_challenge,
+ computer_name);
+ TALLOC_FREE(frame);
+ return status;
+}
+
+/******************************************************************************
+ Wrapper around dbwrap_delete_bystring()
+ Note we must be root here.
+
+ This allows the challenge to be removed from the TDB, which should be
+ as soon as the TDB or in-memory copy it is used, to avoid reuse.
+*******************************************************************************/
+
+NTSTATUS schannel_delete_challenge(struct loadparm_context *lp_ctx,
+ const char *computer_name)
+{
+ TALLOC_CTX *frame = talloc_stackframe();
+ struct db_context *db_sc;
+ char *name_upper;
+ char keystr[16] = { 0, };
+
+ db_sc = open_schannel_session_store(frame, lp_ctx);
+ if (!db_sc) {
+ TALLOC_FREE(frame);
+ return NT_STATUS_ACCESS_DENIED;
+ }
+
+ name_upper = strupper_talloc(frame, computer_name);
+ if (!name_upper) {
+ TALLOC_FREE(frame);
+ return NT_STATUS_NO_MEMORY;
+ }
+
+ hash_computer_name(name_upper, keystr);
+
+ /* Now delete it, we do not want to permit fetch of this twice */
+ dbwrap_delete_bystring(db_sc, keystr);
+
+ TALLOC_FREE(frame);
+ return NT_STATUS_OK;
+}
+
+/******************************************************************************
+ Wrapper around schannel_store_session_key_tdb()
+ Note we must be root here.
+*******************************************************************************/
+
+NTSTATUS schannel_save_challenge(struct loadparm_context *lp_ctx,
+ const struct netr_Credential *client_challenge,
+ const struct netr_Credential *server_challenge,
+ const char *computer_name)
+{
+ TALLOC_CTX *frame = talloc_stackframe();
+ struct db_context *db_sc;
+ NTSTATUS status;
+
+ db_sc = open_schannel_session_store(frame, lp_ctx);
+ if (!db_sc) {
+ TALLOC_FREE(frame);
+ return NT_STATUS_ACCESS_DENIED;
+ }
+
+ status = schannel_store_challenge_tdb(db_sc, frame,
+ client_challenge,
+ server_challenge,
+ computer_name);
+
+ TALLOC_FREE(frame);
+ return status;
+}
+
/********************************************************************
Validate an incoming authenticator against the credentials for the
remote machine stored in the schannel database.