Luna/kernel/src/sys/open.cpp
apio e2a77bb3da
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kernel+libc: Add pledge support
2023-08-12 21:38:25 +02:00

119 lines
3.7 KiB
C++

#include "Log.h"
#include "Pledge.h"
#include "fs/VFS.h"
#include "memory/MemoryManager.h"
#include "sys/Syscall.h"
#include "thread/Scheduler.h"
#include <bits/modes.h>
#include <bits/open-flags.h>
// These flags are needed after open(), the rest only affect open().
constexpr int FLAGS_TO_KEEP = O_RDWR | O_APPEND | O_NONBLOCK;
Result<u64> sys_openat(Registers*, SyscallArgs args)
{
int dirfd = (int)args[0];
auto path = TRY(MemoryManager::strdup_from_user(args[1]));
int flags = (int)args[2];
mode_t mode = (mode_t)args[3];
Thread* current = Scheduler::current();
SharedPtr<VFS::Inode> inode;
// Caller did not pass either O_RDONLY, O_WRONLY or O_RDWR
if ((flags & O_RDWR) == 0) { return err(EINVAL); }
if (flags & O_RDONLY) TRY(check_pledge(current, Promise::p_rpath));
else if (flags & O_WRONLY)
TRY(check_pledge(current, Promise::p_wpath));
if (flags & O_CREAT) TRY(check_pledge(current, Promise::p_cpath));
if (flags & O_TMPFILE)
{
if (!(flags & O_WRONLY)) return err(EINVAL);
if (flags & O_CREAT) return err(EINVAL);
}
int error;
SharedPtr<VFS::Inode> parent_inode;
bool ok = current->resolve_atfile(dirfd, path, false, !(flags & O_NOFOLLOW), &parent_inode)
.try_set_value_or_error(inode, error);
if (!ok)
{
if (error == ENOENT && (flags & O_CREAT) && !path.is_empty())
{
inode = TRY(VFS::create_file(path.chars(), mode & ~current->umask, current->auth, parent_inode));
// FIXME: Pass these in create_file().
auto metadata = inode->metadata();
metadata.uid = current->auth.euid;
metadata.gid = current->auth.egid;
TRY(inode->set_metadata(metadata));
}
else
return err(error);
}
else if (flags & O_EXCL)
return err(EEXIST);
else
{
if ((flags & O_RDONLY) && !VFS::can_read(inode, current->auth)) return err(EACCES);
if ((flags & O_WRONLY) && !VFS::can_write(inode, current->auth)) return err(EACCES);
}
// This should only be possible if O_NOFOLLOW was in flags.
if (inode->type() == VFS::InodeType::Symlink) return err(ELOOP);
if (inode->type() == VFS::InodeType::Socket) return err(ENXIO);
if (flags & O_TMPFILE)
{
if (inode->type() != VFS::InodeType::Directory) return err(EINVAL);
inode = TRY(inode->fs()->create_file_inode(mode & current->umask));
auto metadata = inode->metadata();
metadata.uid = current->auth.euid;
metadata.gid = current->auth.egid;
TRY(inode->set_metadata(metadata));
}
if ((flags & O_WRONLY) && inode->fs() && inode->fs()->is_readonly()) return err(EROFS);
if (inode->type() != VFS::InodeType::Directory && (flags & O_DIRECTORY)) return err(ENOTDIR);
if (inode->type() == VFS::InodeType::Directory)
{
if ((flags & O_WRONLY) || (flags & O_CREAT)) return err(EISDIR);
}
if ((flags & O_WRONLY) && (flags & O_TRUNC)) inode->truncate(0);
int fd = TRY(current->allocate_fd(0));
#ifdef OPEN_DEBUG
kdbgln("openat: opening file %s from dirfd %d, flags %d, mode %#o = fd %d", path.chars(), dirfd, flags, mode, fd);
#endif
current->fd_table[fd] =
FileDescriptor { TRY(make_shared<OpenFileDescription>(inode, flags & FLAGS_TO_KEEP)), 0, flags & O_CLOEXEC };
return (u64)fd;
}
Result<u64> sys_close(Registers*, SyscallArgs args)
{
int fd = (int)args[0];
if (fd < 0 || fd >= FD_MAX) return err(EBADF);
Thread* current = Scheduler::current();
TRY(check_pledge(current, Promise::p_stdio));
Option<FileDescriptor>& descriptor = current->fd_table[fd];
if (!descriptor.has_value()) return err(EBADF);
descriptor = {};
return 0;
}