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- // SPDX-License-Identifier: GPL-2.0
- /*
- * Verified Boot for Embedded (VBE) OS request (device tree fixup) functions
- *
- * Copyright 2022 Google LLC
- * Written by Simon Glass <sjg@chromium.org>
- */
- #define LOG_CATEGORY LOGC_BOOT
- #include <common.h>
- #include <dm.h>
- #include <event.h>
- #include <image.h>
- #include <malloc.h>
- #include <rng.h>
- #include <dm/ofnode.h>
- #define VBE_PREFIX "vbe,"
- #define VBE_PREFIX_LEN (sizeof(VBE_PREFIX) - 1)
- #define VBE_ERR_STR_LEN 128
- #define VBE_MAX_RAND_SIZE 256
- struct vbe_result {
- int errnum;
- char err_str[VBE_ERR_STR_LEN];
- };
- typedef int (*vbe_req_func)(ofnode node, struct vbe_result *result);
- static int handle_random_req(ofnode node, int default_size,
- struct vbe_result *result)
- {
- char buf[VBE_MAX_RAND_SIZE];
- struct udevice *dev;
- u32 size;
- int ret;
- if (!IS_ENABLED(CONFIG_DM_RNG))
- return -ENOTSUPP;
- if (ofnode_read_u32(node, "vbe,size", &size)) {
- if (!default_size) {
- snprintf(result->err_str, VBE_ERR_STR_LEN,
- "Missing vbe,size property");
- return log_msg_ret("byt", -EINVAL);
- }
- size = default_size;
- }
- if (size > VBE_MAX_RAND_SIZE) {
- snprintf(result->err_str, VBE_ERR_STR_LEN,
- "vbe,size %#x exceeds max size %#x", size,
- VBE_MAX_RAND_SIZE);
- return log_msg_ret("siz", -E2BIG);
- }
- ret = uclass_first_device_err(UCLASS_RNG, &dev);
- if (ret) {
- snprintf(result->err_str, VBE_ERR_STR_LEN,
- "Cannot find random-number device (err=%d)", ret);
- return log_msg_ret("wr", ret);
- }
- ret = dm_rng_read(dev, buf, size);
- if (ret) {
- snprintf(result->err_str, VBE_ERR_STR_LEN,
- "Failed to read random-number device (err=%d)", ret);
- return log_msg_ret("rd", ret);
- }
- ret = ofnode_write_prop(node, "data", buf, size, true);
- if (ret)
- return log_msg_ret("wr", -EINVAL);
- return 0;
- }
- static int vbe_req_random_seed(ofnode node, struct vbe_result *result)
- {
- return handle_random_req(node, 0, result);
- }
- static int vbe_req_aslr_move(ofnode node, struct vbe_result *result)
- {
- return -ENOTSUPP;
- }
- static int vbe_req_aslr_rand(ofnode node, struct vbe_result *result)
- {
- return handle_random_req(node, 4, result);
- }
- static int vbe_req_efi_runtime_rand(ofnode node, struct vbe_result *result)
- {
- return handle_random_req(node, 4, result);
- }
- static struct vbe_req {
- const char *compat;
- vbe_req_func func;
- } vbe_reqs[] = {
- /* address space layout randomization - move the OS in memory */
- { "aslr-move", vbe_req_aslr_move },
- /* provide random data for address space layout randomization */
- { "aslr-rand", vbe_req_aslr_rand },
- /* provide random data for EFI-runtime-services address */
- { "efi-runtime-rand", vbe_req_efi_runtime_rand },
- /* generate random data bytes to see the OS's rand generator */
- { "random-rand", vbe_req_random_seed },
- };
- static int vbe_process_request(ofnode node, struct vbe_result *result)
- {
- const char *compat, *req_name;
- int i;
- compat = ofnode_read_string(node, "compatible");
- if (!compat)
- return 0;
- if (strlen(compat) <= VBE_PREFIX_LEN ||
- strncmp(compat, VBE_PREFIX, VBE_PREFIX_LEN))
- return -EINVAL;
- req_name = compat + VBE_PREFIX_LEN; /* drop "vbe," prefix */
- for (i = 0; i < ARRAY_SIZE(vbe_reqs); i++) {
- if (!strcmp(vbe_reqs[i].compat, req_name)) {
- int ret;
- ret = vbe_reqs[i].func(node, result);
- if (ret)
- return log_msg_ret("req", ret);
- return 0;
- }
- }
- snprintf(result->err_str, VBE_ERR_STR_LEN, "Unknown request: %s",
- req_name);
- return -ENOTSUPP;
- }
- /**
- * bootmeth_vbe_ft_fixup() - Process VBE OS requests and do device tree fixups
- *
- * If there are no images provided, this does nothing and returns 0.
- *
- * @ctx: Context for event
- * @event: Event to process
- * @return 0 if OK, -ve on error
- */
- static int bootmeth_vbe_ft_fixup(void *ctx, struct event *event)
- {
- const struct event_ft_fixup *fixup = &event->data.ft_fixup;
- const struct bootm_headers *images = fixup->images;
- ofnode parent, dest_parent, root, node;
- oftree fit;
- if (!images || !images->fit_hdr_os)
- return 0;
- /* Get the image node with requests in it */
- log_debug("fit=%p, noffset=%d\n", images->fit_hdr_os,
- images->fit_noffset_os);
- fit = oftree_from_fdt(images->fit_hdr_os);
- root = oftree_root(fit);
- if (of_live_active()) {
- log_warning("Cannot fix up live tree\n");
- return 0;
- }
- if (!ofnode_valid(root))
- return log_msg_ret("rt", -EINVAL);
- parent = noffset_to_ofnode(root, images->fit_noffset_os);
- if (!ofnode_valid(parent))
- return log_msg_ret("img", -EINVAL);
- dest_parent = oftree_path(fixup->tree, "/chosen");
- if (!ofnode_valid(dest_parent))
- return log_msg_ret("dst", -EINVAL);
- ofnode_for_each_subnode(node, parent) {
- const char *name = ofnode_get_name(node);
- struct vbe_result result;
- ofnode dest;
- int ret;
- log_debug("copy subnode: %s\n", name);
- ret = ofnode_add_subnode(dest_parent, name, &dest);
- if (ret && ret != -EEXIST)
- return log_msg_ret("add", ret);
- ret = ofnode_copy_props(node, dest);
- if (ret)
- return log_msg_ret("cp", ret);
- *result.err_str = '\0';
- ret = vbe_process_request(dest, &result);
- if (ret) {
- result.errnum = ret;
- log_warning("Failed to process VBE request %s (err=%d)\n",
- ofnode_get_name(dest), ret);
- if (*result.err_str) {
- char *msg = strdup(result.err_str);
- if (!msg)
- return log_msg_ret("msg", -ENOMEM);
- ret = ofnode_write_string(dest, "vbe,error",
- msg);
- if (ret) {
- free(msg);
- return log_msg_ret("str", -ENOMEM);
- }
- }
- if (result.errnum) {
- ret = ofnode_write_u32(dest, "vbe,errnum",
- result.errnum);
- if (ret)
- return log_msg_ret("num", -ENOMEM);
- if (result.errnum != -ENOTSUPP)
- return log_msg_ret("pro",
- result.errnum);
- if (result.errnum == -ENOTSUPP &&
- ofnode_read_bool(dest, "vbe,required")) {
- log_err("Cannot handle required request: %s\n",
- ofnode_get_name(dest));
- return log_msg_ret("req",
- result.errnum);
- }
- }
- }
- }
- return 0;
- }
- EVENT_SPY(EVT_FT_FIXUP, bootmeth_vbe_ft_fixup);
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