fs/fuse/ioctl.c

Source file repositories/reference/linux-study-clean/fs/fuse/ioctl.c

File Facts

System
Linux kernel
Corpus path
fs/fuse/ioctl.c
Extension
.c
Size
14693 bytes
Lines
578
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

if (_IOC_DIR(cmd) & _IOC_WRITE) {
			in_iov = iov;
			in_iovs = 1;
		}

		if (_IOC_DIR(cmd) & _IOC_READ) {
			out_iov = iov;
			out_iovs = 1;
		}

		err = 0;
		switch (cmd) {
		case FS_IOC_MEASURE_VERITY:
			err = fuse_setup_measure_verity(arg, iov);
			break;
		case FS_IOC_ENABLE_VERITY:
			err = fuse_setup_enable_verity(arg, iov, &in_iovs);
			break;
		}
		if (err)
			goto out;
	}

 retry:
	inarg.in_size = in_size = iov_length(in_iov, in_iovs);
	inarg.out_size = out_size = iov_length(out_iov, out_iovs);

	/*
	 * Out data can be used either for actual out data or iovs,
	 * make sure there always is at least one page.
	 */
	out_size = max_t(size_t, out_size, PAGE_SIZE);
	max_pages = DIV_ROUND_UP(max(in_size, out_size), PAGE_SIZE);

	/* make sure there are enough buffer pages and init request with them */
	err = -ENOMEM;
	if (max_pages > fm->fc->max_pages)
		goto out;
	while (ap.num_folios < max_pages) {
		ap.folios[ap.num_folios] = folio_alloc(GFP_KERNEL | __GFP_HIGHMEM, 0);
		if (!ap.folios[ap.num_folios])
			goto out;
		ap.num_folios++;
	}

	/* okay, let's send it to the client */
	ap.args.opcode = FUSE_IOCTL;
	ap.args.nodeid = ff->nodeid;
	ap.args.in_numargs = 1;
	ap.args.in_args[0].size = sizeof(inarg);
	ap.args.in_args[0].value = &inarg;
	if (in_size) {
		ap.args.in_numargs++;
		ap.args.in_args[1].size = in_size;
		ap.args.in_pages = true;

		err = -EFAULT;
		iov_iter_init(&ii, ITER_SOURCE, in_iov, in_iovs, in_size);
		for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_folios); i++) {
			c = copy_folio_from_iter(ap.folios[i], 0, PAGE_SIZE, &ii);
			if (c != PAGE_SIZE && iov_iter_count(&ii))
				goto out;
		}
	}

	ap.args.out_numargs = 2;
	ap.args.out_args[1].size = out_size;
	ap.args.out_pages = true;
	ap.args.out_argvar = true;

	transferred = fuse_send_ioctl(fm, &ap.args, &outarg);
	err = transferred;
	if (transferred < 0)
		goto out;

	/* did it ask for retry? */
	if (outarg.flags & FUSE_IOCTL_RETRY) {
		void *vaddr;

		/* no retry if in restricted mode */
		err = -EIO;
		if (!(flags & FUSE_IOCTL_UNRESTRICTED))
			goto out;

		in_iovs = outarg.in_iovs;
		out_iovs = outarg.out_iovs;

		/*
		 * Make sure things are in boundary, separate checks
		 * are to protect against overflow.

Annotation

Implementation Notes