1 // Copyright 2014 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "mojo/public/cpp/bindings/lib/validation_context.h"
6
7 #include <stddef.h>
8 #include <stdint.h>
9
10 #include "base/logging.h"
11 #include "mojo/public/cpp/bindings/lib/serialization_util.h"
12 #include "mojo/public/cpp/bindings/message.h"
13 #include "mojo/public/cpp/system/handle.h"
14
15 namespace mojo {
16 namespace internal {
17
ValidationContext(const void * data,size_t data_num_bytes,size_t num_handles,Message * message,const base::StringPiece & description)18 ValidationContext::ValidationContext(const void* data,
19 size_t data_num_bytes,
20 size_t num_handles,
21 Message* message,
22 const base::StringPiece& description)
23 : message_(message),
24 description_(description),
25 data_begin_(reinterpret_cast<uintptr_t>(data)),
26 data_end_(data_begin_ + data_num_bytes),
27 handle_begin_(0),
28 handle_end_(static_cast<uint32_t>(num_handles)) {
29 if (data_end_ < data_begin_) {
30 // The calculation of |data_end_| overflowed.
31 // It shouldn't happen but if it does, set the range to empty so
32 // IsValidRange() and ClaimMemory() always fail.
33 NOTREACHED();
34 data_end_ = data_begin_;
35 }
36 if (handle_end_ < num_handles) {
37 // Assigning |num_handles| to |handle_end_| overflowed.
38 // It shouldn't happen but if it does, set the handle index range to empty.
39 NOTREACHED();
40 handle_end_ = 0;
41 }
42 }
43
~ValidationContext()44 ValidationContext::~ValidationContext() {
45 }
46
ClaimMemory(const void * position,uint32_t num_bytes)47 bool ValidationContext::ClaimMemory(const void* position, uint32_t num_bytes) {
48 uintptr_t begin = reinterpret_cast<uintptr_t>(position);
49 uintptr_t end = begin + num_bytes;
50
51 if (!InternalIsValidRange(begin, end))
52 return false;
53
54 data_begin_ = end;
55 return true;
56 }
57
ClaimHandle(const Handle_Data & encoded_handle)58 bool ValidationContext::ClaimHandle(const Handle_Data& encoded_handle) {
59 uint32_t index = encoded_handle.value;
60 if (index == kEncodedInvalidHandleValue)
61 return true;
62
63 if (index < handle_begin_ || index >= handle_end_)
64 return false;
65
66 // |index| + 1 shouldn't overflow, because |index| is not the max value of
67 // uint32_t (it is less than |handle_end_|).
68 handle_begin_ = index + 1;
69 return true;
70 }
71
IsValidRange(const void * position,uint32_t num_bytes) const72 bool ValidationContext::IsValidRange(const void* position,
73 uint32_t num_bytes) const {
74 uintptr_t begin = reinterpret_cast<uintptr_t>(position);
75 uintptr_t end = begin + num_bytes;
76
77 return InternalIsValidRange(begin, end);
78 }
79
InternalIsValidRange(uintptr_t begin,uintptr_t end) const80 bool ValidationContext::InternalIsValidRange(uintptr_t begin,
81 uintptr_t end) const {
82 return end > begin && begin >= data_begin_ && end <= data_end_;
83 }
84
85 } // namespace internal
86 } // namespace mojo
87