+static int fuse_ioctl_copy_user(struct page **pages, struct iovec *iov,
+ unsigned int nr_segs, size_t bytes, bool to_user)
+{
+ struct iov_iter ii;
+ int page_idx = 0;
+
+ if (!bytes)
+ return 0;
+
+ iov_iter_init(&ii, iov, nr_segs, bytes, 0);
+
+ while (iov_iter_count(&ii)) {
+ struct page *page = pages[page_idx++];
+ size_t todo = min_t(size_t, PAGE_SIZE, iov_iter_count(&ii));
+ void *kaddr, *map;
+
+ kaddr = map = kmap(page);
+
+ while (todo) {
+ char __user *uaddr = ii.iov->iov_base + ii.iov_offset;
+ size_t iov_len = ii.iov->iov_len - ii.iov_offset;
+ size_t copy = min(todo, iov_len);
+ size_t left;
+
+ if (!to_user)
+ left = copy_from_user(kaddr, uaddr, copy);
+ else
+ left = copy_to_user(uaddr, kaddr, copy);
+
+ if (unlikely(left))
+ return -EFAULT;
+
+ iov_iter_advance(&ii, copy);
+ todo -= copy;
+ kaddr += copy;
+ }
+
+ kunmap(map);
+ }
+
+ return 0;
+}
+
+/*
+ * For ioctls, there is no generic way to determine how much memory
+ * needs to be read and/or written. Furthermore, ioctls are allowed
+ * to dereference the passed pointer, so the parameter requires deep
+ * copying but FUSE has no idea whatsoever about what to copy in or
+ * out.
+ *
+ * This is solved by allowing FUSE server to retry ioctl with
+ * necessary in/out iovecs. Let's assume the ioctl implementation
+ * needs to read in the following structure.
+ *
+ * struct a {
+ * char *buf;
+ * size_t buflen;
+ * }
+ *
+ * On the first callout to FUSE server, inarg->in_size and
+ * inarg->out_size will be NULL; then, the server completes the ioctl
+ * with FUSE_IOCTL_RETRY set in out->flags, out->in_iovs set to 1 and
+ * the actual iov array to
+ *
+ * { { .iov_base = inarg.arg, .iov_len = sizeof(struct a) } }
+ *
+ * which tells FUSE to copy in the requested area and retry the ioctl.
+ * On the second round, the server has access to the structure and
+ * from that it can tell what to look for next, so on the invocation,
+ * it sets FUSE_IOCTL_RETRY, out->in_iovs to 2 and iov array to
+ *
+ * { { .iov_base = inarg.arg, .iov_len = sizeof(struct a) },
+ * { .iov_base = a.buf, .iov_len = a.buflen } }
+ *
+ * FUSE will copy both struct a and the pointed buffer from the
+ * process doing the ioctl and retry ioctl with both struct a and the
+ * buffer.
+ *
+ * This time, FUSE server has everything it needs and completes ioctl
+ * without FUSE_IOCTL_RETRY which finishes the ioctl call.
+ *
+ * Copying data out works the same way.
+ *
+ * Note that if FUSE_IOCTL_UNRESTRICTED is clear, the kernel
+ * automatically initializes in and out iovs by decoding @cmd with
+ * _IOC_* macros and the server is not allowed to request RETRY. This
+ * limits ioctl data transfers to well-formed ioctls and is the forced
+ * behavior for all FUSE servers.
+ */
+static long fuse_file_do_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg, unsigned int flags)
+{
+ struct inode *inode = file->f_dentry->d_inode;
+ struct fuse_file *ff = file->private_data;
+ struct fuse_conn *fc = get_fuse_conn(inode);
+ struct fuse_ioctl_in inarg = {
+ .fh = ff->fh,
+ .cmd = cmd,
+ .arg = arg,
+ .flags = flags
+ };
+ struct fuse_ioctl_out outarg;
+ struct fuse_req *req = NULL;
+ struct page **pages = NULL;
+ struct page *iov_page = NULL;
+ struct iovec *in_iov = NULL, *out_iov = NULL;
+ unsigned int in_iovs = 0, out_iovs = 0, num_pages = 0, max_pages;
+ size_t in_size, out_size, transferred;
+ int err;
+
+ /* assume all the iovs returned by client always fits in a page */
+ BUILD_BUG_ON(sizeof(struct iovec) * FUSE_IOCTL_MAX_IOV > PAGE_SIZE);
+
+ if (!fuse_allow_task(fc, current))
+ return -EACCES;
+
+ err = -EIO;
+ if (is_bad_inode(inode))
+ goto out;
+
+ err = -ENOMEM;
+ pages = kzalloc(sizeof(pages[0]) * FUSE_MAX_PAGES_PER_REQ, GFP_KERNEL);
+ iov_page = alloc_page(GFP_KERNEL);
+ if (!pages || !iov_page)
+ goto out;
+
+ /*
+ * If restricted, initialize IO parameters as encoded in @cmd.
+ * RETRY from server is not allowed.
+ */
+ if (!(flags & FUSE_IOCTL_UNRESTRICTED)) {
+ struct iovec *iov = page_address(iov_page);
+
+ iov->iov_base = (void *)arg;
+ iov->iov_len = _IOC_SIZE(cmd);
+
+ if (_IOC_DIR(cmd) & _IOC_WRITE) {
+ in_iov = iov;
+ in_iovs = 1;
+ }
+
+ if (_IOC_DIR(cmd) & _IOC_READ) {
+ out_iov = iov;
+ out_iovs = 1;
+ }
+ }
+
+ 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 > FUSE_MAX_PAGES_PER_REQ)
+ goto out;
+ while (num_pages < max_pages) {
+ pages[num_pages] = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
+ if (!pages[num_pages])
+ goto out;
+ num_pages++;
+ }
+
+ req = fuse_get_req(fc);
+ if (IS_ERR(req)) {
+ err = PTR_ERR(req);
+ req = NULL;
+ goto out;
+ }
+ memcpy(req->pages, pages, sizeof(req->pages[0]) * num_pages);
+ req->num_pages = num_pages;
+
+ /* okay, let's send it to the client */
+ req->in.h.opcode = FUSE_IOCTL;
+ req->in.h.nodeid = get_node_id(inode);
+ req->in.numargs = 1;
+ req->in.args[0].size = sizeof(inarg);
+ req->in.args[0].value = &inarg;
+ if (in_size) {
+ req->in.numargs++;
+ req->in.args[1].size = in_size;
+ req->in.argpages = 1;
+
+ err = fuse_ioctl_copy_user(pages, in_iov, in_iovs, in_size,
+ false);
+ if (err)
+ goto out;
+ }
+
+ req->out.numargs = 2;
+ req->out.args[0].size = sizeof(outarg);
+ req->out.args[0].value = &outarg;
+ req->out.args[1].size = out_size;
+ req->out.argpages = 1;
+ req->out.argvar = 1;
+
+ request_send(fc, req);
+ err = req->out.h.error;
+ transferred = req->out.args[1].size;
+ fuse_put_request(fc, req);
+ req = NULL;
+ if (err)
+ goto out;
+
+ /* did it ask for retry? */
+ if (outarg.flags & FUSE_IOCTL_RETRY) {
+ char *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.
+ */
+ err = -ENOMEM;
+ if (in_iovs > FUSE_IOCTL_MAX_IOV ||
+ out_iovs > FUSE_IOCTL_MAX_IOV ||
+ in_iovs + out_iovs > FUSE_IOCTL_MAX_IOV)
+ goto out;
+
+ err = -EIO;
+ if ((in_iovs + out_iovs) * sizeof(struct iovec) != transferred)
+ goto out;
+
+ /* okay, copy in iovs and retry */
+ vaddr = kmap_atomic(pages[0], KM_USER0);
+ memcpy(page_address(iov_page), vaddr, transferred);
+ kunmap_atomic(vaddr, KM_USER0);
+
+ in_iov = page_address(iov_page);
+ out_iov = in_iov + in_iovs;
+
+ goto retry;
+ }
+
+ err = -EIO;
+ if (transferred > inarg.out_size)
+ goto out;
+
+ err = fuse_ioctl_copy_user(pages, out_iov, out_iovs, transferred, true);
+ out:
+ if (req)
+ fuse_put_request(fc, req);
+ if (iov_page)
+ __free_page(iov_page);
+ while (num_pages)
+ __free_page(pages[--num_pages]);
+ kfree(pages);
+
+ return err ? err : outarg.result;
+}
+
+static long fuse_file_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ return fuse_file_do_ioctl(file, cmd, arg, 0);
+}
+
+static long fuse_file_compat_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ return fuse_file_do_ioctl(file, cmd, arg, FUSE_IOCTL_COMPAT);
+}
+
projects / linux-2.6-omap-h63xx.git / commitdiff