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Kernel+Userland: Split bind-mounting and re-mounting from mount syscall

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These 2 are an actual separate types of syscalls, so let's stop using
special flags for bind mounting or re-mounting and instead let userspace
calling directly for this kind of actions.
This commit is contained in:
Liav A 2023-02-25 19:30:28 +02:00 • committed by Andrew Kaster
parent 04b44a827a
commit 0bbd9040ef
10 changed files with 204 additions and 42 deletions
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71
Kernel/Syscalls/mount.cpp
View file

@ -77,6 +77,10 @@ ErrorOr<FlatPtr> Process::sys$mount(Userspace<Syscall::SC_mount_params const*> u
return EPERM;
auto params = TRY(copy_typed_from_user(user_params));
if (params.flags & MS_REMOUNT)
return EINVAL;
if (params.flags & MS_BIND)
return EINVAL;
auto source_fd = params.source_fd;
auto target = TRY(try_copy_kstring_from_user(params.target));
@ -91,25 +95,6 @@ ErrorOr<FlatPtr> Process::sys$mount(Userspace<Syscall::SC_mount_params const*> u
auto target_custody = TRY(VirtualFileSystem::the().resolve_path(credentials, target->view(), current_directory()));
if (params.flags & MS_REMOUNT) {
// We're not creating a new mount, we're updating an existing one!
TRY(VirtualFileSystem::the().remount(target_custody, params.flags & ~MS_REMOUNT));
return 0;
}
if (params.flags & MS_BIND) {
// We're doing a bind mount.
if (description_or_error.is_error())
return description_or_error.release_error();
auto description = description_or_error.release_value();
if (!description->custody()) {
// We only support bind-mounting inodes, not arbitrary files.
return ENODEV;
}
TRY(VirtualFileSystem::the().bind_mount(*description->custody(), target_custody, params.flags));
return 0;
}
RefPtr<FileSystem> fs;
if (!description_or_error.is_error()) {
@ -126,6 +111,54 @@ ErrorOr<FlatPtr> Process::sys$mount(Userspace<Syscall::SC_mount_params const*> u
return 0;
}
ErrorOr<FlatPtr> Process::sys$remount(Userspace<Syscall::SC_remount_params const*> user_params)
{
VERIFY_NO_PROCESS_BIG_LOCK(this);
TRY(require_no_promises());
auto credentials = this->credentials();
if (!credentials->is_superuser())
return EPERM;
auto params = TRY(copy_typed_from_user(user_params));
if (params.flags & MS_REMOUNT)
return EINVAL;
if (params.flags & MS_BIND)
return EINVAL;
auto target = TRY(try_copy_kstring_from_user(params.target));
auto target_custody = TRY(VirtualFileSystem::the().resolve_path(credentials, target->view(), current_directory()));
TRY(VirtualFileSystem::the().remount(target_custody, params.flags));
return 0;
}
ErrorOr<FlatPtr> Process::sys$bindmount(Userspace<Syscall::SC_bindmount_params const*> user_params)
{
VERIFY_NO_PROCESS_BIG_LOCK(this);
TRY(require_no_promises());
auto credentials = this->credentials();
if (!credentials->is_superuser())
return EPERM;
auto params = TRY(copy_typed_from_user(user_params));
if (params.flags & MS_REMOUNT)
return EINVAL;
if (params.flags & MS_BIND)
return EINVAL;
auto source_fd = params.source_fd;
auto target = TRY(try_copy_kstring_from_user(params.target));
auto target_custody = TRY(VirtualFileSystem::the().resolve_path(credentials, target->view(), current_directory()));
auto description = TRY(open_file_description(source_fd));
if (!description->custody()) {
// NOTE: We only support bind-mounting inodes, not arbitrary files.
return ENODEV;
}
TRY(VirtualFileSystem::the().bind_mount(*description->custody(), target_custody, params.flags));
return 0;
}
ErrorOr<FlatPtr> Process::sys$umount(Userspace<char const*> user_mountpoint, size_t mountpoint_length)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);