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https://github.com/RGBCube/serenity
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9559682f5c
We now disallow jail creation from a process within a jail because there is simply no valid use case to allow it, and we will probably not enable this behavior (which is considered a bug) again. Although there was no "real" security issue with this bug, as a process would still be denied to join that jail, there's an information reveal about the amount of jails that are or were present in the system.
67 lines
2.4 KiB
C++
67 lines
2.4 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Userspace.h>
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#include <Kernel/Jail.h>
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#include <Kernel/JailManagement.h>
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#include <Kernel/Process.h>
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#include <Kernel/StdLib.h>
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#include <LibC/sys/ioctl_numbers.h>
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namespace Kernel {
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constexpr size_t jail_name_max_size = 50;
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ErrorOr<FlatPtr> Process::sys$jail_create(Userspace<Syscall::SC_jail_create_params*> user_params)
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{
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VERIFY_NO_PROCESS_BIG_LOCK(this);
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TRY(require_promise(Pledge::jail));
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auto params = TRY(copy_typed_from_user(user_params));
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auto jail_name = TRY(get_syscall_path_argument(params.name));
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if (jail_name->length() > jail_name_max_size)
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return ENAMETOOLONG;
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params.index = TRY(m_attached_jail.with([&](auto& my_jail) -> ErrorOr<u64> {
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// Note: If we are already in a jail, don't let the process to be able to create other jails
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// even if it will not be able to join them later on. The reason for this is to prevent as much as possible
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// any info leak about the "outside world" jail metadata.
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if (my_jail)
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return Error::from_errno(EPERM);
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auto jail = TRY(JailManagement::the().create_jail(move(jail_name)));
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return jail->index().value();
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}));
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// Note: We do the copy_to_user outside of the m_attached_jail Spinlock locked scope because
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// we rely on page faults to work properly.
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TRY(copy_to_user(user_params, ¶ms));
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return 0;
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}
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ErrorOr<FlatPtr> Process::sys$jail_attach(Userspace<Syscall::SC_jail_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::jail));
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auto params = TRY(copy_typed_from_user(user_params));
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return m_attached_jail.with([&](auto& my_jail) -> ErrorOr<FlatPtr> {
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// Note: If we are already in a jail, don't let the process escape it even if
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// it knows there are other jails.
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// Note: To ensure the process doesn't try to maliciously enumerate all jails
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// in the system, just return EPERM before doing anything else.
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if (my_jail)
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return EPERM;
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auto jail = JailManagement::the().find_jail_by_index(static_cast<JailIndex>(params.index));
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if (!jail)
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return EINVAL;
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my_jail = *jail;
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my_jail->attach_count().with([&](auto& attach_count) {
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attach_count++;
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});
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return 0;
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});
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}
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}
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