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Diffstat (limited to 'sandbox/win/src/policy_engine_processor.cc')
-rw-r--r-- | sandbox/win/src/policy_engine_processor.cc | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/sandbox/win/src/policy_engine_processor.cc b/sandbox/win/src/policy_engine_processor.cc new file mode 100644 index 0000000..d0455d0 --- /dev/null +++ b/sandbox/win/src/policy_engine_processor.cc @@ -0,0 +1,107 @@ +// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +#include "sandbox/src/policy_engine_processor.h" + +namespace sandbox { + +void PolicyProcessor::SetInternalState(size_t index, EvalResult result) { + state_.current_index_ = index; + state_.current_result_ = result; +} + +EvalResult PolicyProcessor::GetAction() const { + return state_.current_result_; +} + +// Decides if an opcode can be skipped (not evaluated) or not. The function +// takes as inputs the opcode and the current evaluation context and returns +// true if the opcode should be skipped or not and also can set keep_skipping +// to false to signal that the current instruction should be skipped but not +// the next after the current one. +bool SkipOpcode(PolicyOpcode& opcode, MatchContext* context, + bool* keep_skipping) { + if (opcode.IsAction()) { + uint32 options = context->options; + context->Clear(); + *keep_skipping = false; + return (kPolUseOREval == options)? false : true; + } + *keep_skipping = true; + return true; +} + +PolicyResult PolicyProcessor::Evaluate(uint32 options, + ParameterSet* parameters, + size_t param_count) { + if (NULL == policy_) { + return NO_POLICY_MATCH; + } + if (0 == policy_->opcode_count) { + return NO_POLICY_MATCH; + } + if (!(kShortEval & options)) { + return POLICY_ERROR; + } + + MatchContext context; + bool evaluation = false; + bool skip_group = false; + SetInternalState(0, EVAL_FALSE); + size_t count = policy_->opcode_count; + + // Loop over all the opcodes Evaluating in sequence. Since we only support + // short circuit evaluation, we stop as soon as we find an 'action' opcode + // and the current evaluation is true. + // + // Skipping opcodes can happen when we are in AND mode (!kPolUseOREval) and + // have got EVAL_FALSE or when we are in OR mode (kPolUseOREval) and got + // EVAL_TRUE. Skipping will stop at the next action opcode or at the opcode + // after the action depending on kPolUseOREval. + + for (size_t ix = 0; ix != count; ++ix) { + PolicyOpcode& opcode = policy_->opcodes[ix]; + // Skipping block. + if (skip_group) { + if (SkipOpcode(opcode, &context, &skip_group)) { + continue; + } + } + // Evaluation block. + EvalResult result = opcode.Evaluate(parameters, param_count, &context); + switch (result) { + case EVAL_FALSE: + evaluation = false; + if (kPolUseOREval != context.options) { + skip_group = true; + } + break; + case EVAL_ERROR: + if (kStopOnErrors & options) { + return POLICY_ERROR; + } + break; + case EVAL_TRUE: + evaluation = true; + if (kPolUseOREval == context.options) { + skip_group = true; + } + break; + default: + // We have evaluated an action. + SetInternalState(ix, result); + return POLICY_MATCH; + } + } + + if (evaluation) { + // Reaching the end of the policy with a positive evaluation is probably + // an error: we did not find a final action opcode? + return POLICY_ERROR; + } + return NO_POLICY_MATCH; +} + + +} // namespace sandbox |