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940380c986
This addresses the issue first enountered in #3644. If a path is first unveiled with "c" permissions, we should NOT return ENOENT if the node does not exist on the disk, as the program will most likely be creating it at a later time.
120 lines
4.7 KiB
C++
120 lines
4.7 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <AK/LexicalPath.h>
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#include <AK/StringView.h>
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#include <Kernel/FileSystem/Custody.h>
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#include <Kernel/FileSystem/VirtualFileSystem.h>
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#include <Kernel/Process.h>
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namespace Kernel {
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int Process::sys$unveil(Userspace<const Syscall::SC_unveil_params*> user_params)
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{
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Syscall::SC_unveil_params params;
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if (!copy_from_user(¶ms, user_params))
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return -EFAULT;
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if (!params.path.characters && !params.permissions.characters) {
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m_veil_state = VeilState::Locked;
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return 0;
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}
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if (m_veil_state == VeilState::Locked)
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return -EPERM;
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if (!params.path.characters || !params.permissions.characters)
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return -EINVAL;
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if (params.permissions.length > 4)
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return -EINVAL;
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auto path = get_syscall_path_argument(params.path);
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if (path.is_error())
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return path.error();
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if (path.value().is_empty() || path.value().characters()[0] != '/')
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return -EINVAL;
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auto permissions = copy_string_from_user(params.permissions);
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if (permissions.is_null())
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return -EFAULT;
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// Let's work out permissions first...
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unsigned new_permissions = 0;
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for (const char permission : permissions) {
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switch (permission) {
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case 'r':
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new_permissions |= UnveiledPath::Access::Read;
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break;
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case 'w':
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new_permissions |= UnveiledPath::Access::Write;
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break;
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case 'x':
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new_permissions |= UnveiledPath::Access::Execute;
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break;
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case 'c':
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new_permissions |= UnveiledPath::Access::CreateOrRemove;
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break;
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default:
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return -EINVAL;
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}
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}
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// Now, let's try and resolve the path and obtain custody of the inode on the disk, and if not, bail out with
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// the error from resolve_path_without_veil()
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// However, if the user specified unveil() with "c" permissions, we don't set errno if ENOENT is encountered,
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// because they most likely intend the program to create the file for them later on.
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// If this case is encountered, the parent node of the path is returned and the custody of that inode is used instead.
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RefPtr<Custody> parent_custody; // Parent inode in case of ENOENT
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String new_unveiled_path;
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auto custody_or_error = VFS::the().resolve_path_without_veil(path.value(), root_directory(), &parent_custody);
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if (!custody_or_error.is_error()) {
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new_unveiled_path = custody_or_error.value()->absolute_path();
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} else if (custody_or_error.error() == -ENOENT && parent_custody && (new_permissions & UnveiledPath::Access::CreateOrRemove)) {
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String basename = LexicalPath(path.value()).basename();
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new_unveiled_path = String::formatted("{}/{}", parent_custody->absolute_path(), basename);
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} else {
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// FIXME Should this be EINVAL?
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return custody_or_error.error();
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}
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for (auto& unveiled_path : m_unveiled_paths) {
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if (unveiled_path.path == new_unveiled_path) {
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if (new_permissions & ~unveiled_path.permissions)
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return -EPERM;
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unveiled_path.permissions = new_permissions;
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return 0;
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}
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}
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m_unveiled_paths.append({ new_unveiled_path, new_permissions });
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ASSERT(m_veil_state != VeilState::Locked);
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m_veil_state = VeilState::Dropped;
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return 0;
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}
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}
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