| // Copyright (c) 2011 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 "ipc/ipc_message_attachment_set.h" |
| |
| #include <stddef.h> |
| |
| #include <algorithm> |
| |
| #include "base/logging.h" |
| #include "base/posix/eintr_wrapper.h" |
| #include "build/build_config.h" |
| #include "ipc/ipc_message_attachment.h" |
| |
| namespace IPC { |
| |
| namespace { |
| |
| unsigned count_attachments_of_type( |
| const std::vector<scoped_refptr<MessageAttachment>>& attachments, |
| MessageAttachment::Type type) { |
| unsigned count = 0; |
| for (const scoped_refptr<MessageAttachment>& attachment : attachments) { |
| if (attachment->GetType() == type) |
| ++count; |
| } |
| return count; |
| } |
| |
| } // namespace |
| |
| MessageAttachmentSet::MessageAttachmentSet() |
| : consumed_descriptor_highwater_(0) { |
| } |
| |
| MessageAttachmentSet::~MessageAttachmentSet() { |
| if (consumed_descriptor_highwater_ == size()) |
| return; |
| |
| // We close all the owning descriptors. If this message should have |
| // been transmitted, then closing those with close flags set mirrors |
| // the expected behaviour. |
| // |
| // If this message was received with more descriptors than expected |
| // (which could a DOS against the browser by a rogue renderer) then all |
| // the descriptors have their close flag set and we free all the extra |
| // kernel resources. |
| LOG(WARNING) << "MessageAttachmentSet destroyed with unconsumed attachments: " |
| << consumed_descriptor_highwater_ << "/" << size(); |
| } |
| |
| unsigned MessageAttachmentSet::num_descriptors() const { |
| return count_attachments_of_type(attachments_, |
| MessageAttachment::Type::PLATFORM_FILE); |
| } |
| |
| unsigned MessageAttachmentSet::size() const { |
| return static_cast<unsigned>(attachments_.size()); |
| } |
| |
| bool MessageAttachmentSet::AddAttachment( |
| scoped_refptr<MessageAttachment> attachment, |
| size_t* index) { |
| #if BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA) |
| if (attachment->GetType() == MessageAttachment::Type::PLATFORM_FILE && |
| num_descriptors() == kMaxDescriptorsPerMessage) { |
| DLOG(WARNING) << "Cannot add file descriptor. MessageAttachmentSet full."; |
| return false; |
| } |
| #endif |
| |
| switch (attachment->GetType()) { |
| case MessageAttachment::Type::PLATFORM_FILE: |
| case MessageAttachment::Type::MOJO_HANDLE: |
| case MessageAttachment::Type::WIN_HANDLE: |
| case MessageAttachment::Type::MACH_PORT: |
| case MessageAttachment::Type::FUCHSIA_HANDLE: |
| attachments_.push_back(attachment); |
| *index = attachments_.size() - 1; |
| return true; |
| } |
| return false; |
| } |
| |
| bool MessageAttachmentSet::AddAttachment( |
| scoped_refptr<MessageAttachment> attachment) { |
| size_t index; |
| return AddAttachment(attachment, &index); |
| } |
| |
| scoped_refptr<MessageAttachment> MessageAttachmentSet::GetAttachmentAt( |
| unsigned index) { |
| if (index >= size()) { |
| DLOG(WARNING) << "Accessing out of bound index:" << index << "/" << size(); |
| return scoped_refptr<MessageAttachment>(); |
| } |
| |
| // We should always walk the descriptors in order, so it's reasonable to |
| // enforce this. Consider the case where a compromised renderer sends us |
| // the following message: |
| // |
| // ExampleMsg: |
| // num_fds:2 msg:FD(index = 1) control:SCM_RIGHTS {n, m} |
| // |
| // Here the renderer sent us a message which should have a descriptor, but |
| // actually sent two in an attempt to fill our fd table and kill us. By |
| // setting the index of the descriptor in the message to 1 (it should be |
| // 0), we would record a highwater of 1 and then consider all the |
| // descriptors to have been used. |
| // |
| // So we can either track of the use of each descriptor in a bitset, or we |
| // can enforce that we walk the indexes strictly in order. |
| if (index == 0 && consumed_descriptor_highwater_ == size()) { |
| DLOG(WARNING) << "Attempted to double-read a message attachment, " |
| "returning a nullptr"; |
| } |
| |
| if (index != consumed_descriptor_highwater_) |
| return scoped_refptr<MessageAttachment>(); |
| |
| consumed_descriptor_highwater_ = index + 1; |
| |
| return attachments_[index]; |
| } |
| |
| void MessageAttachmentSet::CommitAllDescriptors() { |
| attachments_.clear(); |
| consumed_descriptor_highwater_ = 0; |
| } |
| |
| } // namespace IPC |