As a starting point, add support for providing random data, if requested by the OS. Also add ASLR, as a placeholder for now.
Signed-off-by: Simon Glass sjg@chromium.org ---
boot/Makefile | 2 +- boot/vbe_fixup.c | 233 +++++++++++++++++++++++++++++++ test/py/tests/test_event_dump.py | 1 + 3 files changed, 235 insertions(+), 1 deletion(-) create mode 100644 boot/vbe_fixup.c
diff --git a/boot/Makefile b/boot/Makefile index 67e335255f1..dd45d786f8c 100644 --- a/boot/Makefile +++ b/boot/Makefile @@ -47,5 +47,5 @@ ifdef CONFIG_SPL_BUILD obj-$(CONFIG_SPL_LOAD_FIT) += common_fit.o endif
-obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_VBE) += vbe.o +obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_VBE) += vbe.o vbe_fixup.o obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_VBE_SIMPLE) += vbe_simple.o diff --git a/boot/vbe_fixup.c b/boot/vbe_fixup.c new file mode 100644 index 00000000000..8cdff6972b1 --- /dev/null +++ b/boot/vbe_fixup.c @@ -0,0 +1,233 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Verified Boot for Embedded (VBE) 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_check(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_err("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); diff --git a/test/py/tests/test_event_dump.py b/test/py/tests/test_event_dump.py index bc54149e8f2..e63c25df537 100644 --- a/test/py/tests/test_event_dump.py +++ b/test/py/tests/test_event_dump.py @@ -16,6 +16,7 @@ def test_event_dump(u_boot_console): out = util.run_and_log(cons, ['scripts/event_dump.py', sandbox]) expect = '''.*Event type Id Source location -------------------- ------------------------------ ------------------------------ +EVT_FT_FIXUP bootmeth_vbe_ft_fixup .*boot/vbe_fixup.c:.* EVT_FT_FIXUP bootmeth_vbe_simple_ft_fixup .*boot/vbe_simple.c:.* EVT_MISC_INIT_F sandbox_misc_init_f .*arch/sandbox/cpu/start.c:''' assert re.match(expect, out, re.MULTILINE) is not None