mirror of
https://github.com/SerenityOS/serenity.git
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Liav A.
1dfc9e2df3
Immutable mounts are mounts that can't be changed in any aspect, if the VFSRootContext that hold them is used by a process. This includes two operations on a mount: 1. Trying to remove the mount from the mount table. 2. Trying to change the flags of the mount. The condition of a VFSRootContext being held by a process or not is crucial, as the intention is to allow removal of mounts that marked as immutable if the VFSRootContext is not being used anymore (for example, if the container that was created with such context stopped). Marking mounts as immutable on the first VFS root context essentially ensures they will never be modified because there will be a process using that context (which is the "main" VFS root context in the system runtime). It should be noted that setting a mount as immutable can be done in creation time of the mount by passing the MS_IMMUTABLE flag, or by doing a remount with MS_IMMUTABLE flag.
101 lines
3.2 KiB
C++
101 lines
3.2 KiB
C++
/*
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* Copyright (c) 2024, Liav A. <[email protected]>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/API/Unshare.h>
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#include <Kernel/FileSystem/VFSRootContext.h>
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#include <Kernel/Tasks/Process.h>
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#include <Kernel/Tasks/ScopedProcessList.h>
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namespace Kernel {
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ErrorOr<FlatPtr> Process::sys$unshare_create(Userspace<Syscall::SC_unshare_create_params const*> user_params)
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{
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VERIFY_NO_PROCESS_BIG_LOCK(this);
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TRY(require_promise(Pledge::unshare));
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if (is_jailed())
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return EPERM;
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auto credentials = this->credentials();
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if (!credentials->is_superuser())
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return EPERM;
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auto params = TRY(copy_typed_from_user(user_params));
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if (params.type < 0)
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return EINVAL;
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switch (static_cast<UnshareType>(params.type)) {
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case UnshareType::ScopedProcessList: {
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auto new_process_list = TRY(ScopedProcessList::create());
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return new_process_list->id().value();
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}
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case UnshareType::VFSRootContext: {
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auto new_vfs_root_context = TRY(VFSRootContext::create_with_empty_ramfs());
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return new_vfs_root_context->id().value();
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}
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case UnshareType::HostnameContext: {
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TRY(m_attached_hostname_context.with([](auto& context) -> ErrorOr<void> {
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FixedStringBuffer<UTSNAME_ENTRY_LEN - 1> hostname;
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context->buffer().with([&hostname](auto& buffer) {
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hostname.store_characters(buffer.representable_view());
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});
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// NOTE: Create a new context, based on the contents of previous attached one.
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context = TRY(HostnameContext::create_with_name(hostname.representable_view()));
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return {};
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}));
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return 0;
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}
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}
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return Error::from_errno(ENOTSUP);
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}
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ErrorOr<FlatPtr> Process::sys$unshare_attach(Userspace<Syscall::SC_unshare_attach_params const*> user_params)
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{
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VERIFY_NO_PROCESS_BIG_LOCK(this);
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TRY(require_promise(Pledge::unshare));
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if (is_jailed())
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return EPERM;
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auto credentials = this->credentials();
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if (!credentials->is_superuser())
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return EPERM;
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auto params = TRY(copy_typed_from_user(user_params));
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if (params.type < 0)
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return EINVAL;
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switch (static_cast<UnshareType>(params.type)) {
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case UnshareType::ScopedProcessList: {
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auto scoped_process_list = TRY(ScopedProcessList::scoped_process_list_for_id(params.id));
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m_scoped_process_list.with([this, scoped_process_list](auto& list_ptr) {
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list_ptr = scoped_process_list;
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list_ptr->attach(*this);
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});
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return 0;
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}
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case UnshareType::VFSRootContext: {
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auto vfs_root_context = TRY(vfs_root_context_for_id(params.id));
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m_attached_vfs_root_context.with([vfs_root_context](auto& context) {
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context = vfs_root_context;
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});
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vfs_root_context->attach({});
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return 0;
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}
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case UnshareType::HostnameContext: {
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auto hostname_context = TRY(HostnameContext::hostname_context_for_id(params.id));
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m_attached_hostname_context.with([hostname_context](auto& context) {
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context = hostname_context;
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});
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hostname_context->set_attached({});
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return 0;
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}
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}
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return Error::from_errno(ENOTSUP);
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}
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}
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