Simon Glass | 386d05d | 2022-10-11 09:47:18 -0600 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | /* |
Simon Glass | 5a09137 | 2022-10-20 18:23:05 -0600 | [diff] [blame] | 3 | * Verified Boot for Embedded (VBE) OS request (device tree fixup) functions |
Simon Glass | 386d05d | 2022-10-11 09:47:18 -0600 | [diff] [blame] | 4 | * |
| 5 | * Copyright 2022 Google LLC |
| 6 | * Written by Simon Glass <sjg@chromium.org> |
| 7 | */ |
| 8 | |
| 9 | #define LOG_CATEGORY LOGC_BOOT |
| 10 | |
| 11 | #include <common.h> |
| 12 | #include <dm.h> |
| 13 | #include <event.h> |
| 14 | #include <image.h> |
| 15 | #include <malloc.h> |
| 16 | #include <rng.h> |
| 17 | #include <dm/ofnode.h> |
| 18 | |
| 19 | #define VBE_PREFIX "vbe," |
| 20 | #define VBE_PREFIX_LEN (sizeof(VBE_PREFIX) - 1) |
| 21 | #define VBE_ERR_STR_LEN 128 |
| 22 | #define VBE_MAX_RAND_SIZE 256 |
| 23 | |
| 24 | struct vbe_result { |
| 25 | int errnum; |
| 26 | char err_str[VBE_ERR_STR_LEN]; |
| 27 | }; |
| 28 | |
| 29 | typedef int (*vbe_req_func)(ofnode node, struct vbe_result *result); |
| 30 | |
| 31 | static int handle_random_req(ofnode node, int default_size, |
| 32 | struct vbe_result *result) |
| 33 | { |
| 34 | char buf[VBE_MAX_RAND_SIZE]; |
| 35 | struct udevice *dev; |
| 36 | u32 size; |
| 37 | int ret; |
| 38 | |
Simon Glass | 55d25b5 | 2023-02-22 09:33:53 -0700 | [diff] [blame] | 39 | if (!IS_ENABLED(CONFIG_DM_RNG)) |
Simon Glass | 386d05d | 2022-10-11 09:47:18 -0600 | [diff] [blame] | 40 | return -ENOTSUPP; |
| 41 | |
| 42 | if (ofnode_read_u32(node, "vbe,size", &size)) { |
| 43 | if (!default_size) { |
| 44 | snprintf(result->err_str, VBE_ERR_STR_LEN, |
| 45 | "Missing vbe,size property"); |
| 46 | return log_msg_ret("byt", -EINVAL); |
| 47 | } |
| 48 | size = default_size; |
| 49 | } |
| 50 | if (size > VBE_MAX_RAND_SIZE) { |
| 51 | snprintf(result->err_str, VBE_ERR_STR_LEN, |
| 52 | "vbe,size %#x exceeds max size %#x", size, |
| 53 | VBE_MAX_RAND_SIZE); |
| 54 | return log_msg_ret("siz", -E2BIG); |
| 55 | } |
| 56 | ret = uclass_first_device_err(UCLASS_RNG, &dev); |
| 57 | if (ret) { |
| 58 | snprintf(result->err_str, VBE_ERR_STR_LEN, |
| 59 | "Cannot find random-number device (err=%d)", ret); |
| 60 | return log_msg_ret("wr", ret); |
| 61 | } |
| 62 | ret = dm_rng_read(dev, buf, size); |
| 63 | if (ret) { |
| 64 | snprintf(result->err_str, VBE_ERR_STR_LEN, |
| 65 | "Failed to read random-number device (err=%d)", ret); |
| 66 | return log_msg_ret("rd", ret); |
| 67 | } |
| 68 | ret = ofnode_write_prop(node, "data", buf, size, true); |
| 69 | if (ret) |
| 70 | return log_msg_ret("wr", -EINVAL); |
| 71 | |
| 72 | return 0; |
| 73 | } |
| 74 | |
| 75 | static int vbe_req_random_seed(ofnode node, struct vbe_result *result) |
| 76 | { |
| 77 | return handle_random_req(node, 0, result); |
| 78 | } |
| 79 | |
| 80 | static int vbe_req_aslr_move(ofnode node, struct vbe_result *result) |
| 81 | { |
| 82 | return -ENOTSUPP; |
| 83 | } |
| 84 | |
| 85 | static int vbe_req_aslr_rand(ofnode node, struct vbe_result *result) |
| 86 | { |
| 87 | return handle_random_req(node, 4, result); |
| 88 | } |
| 89 | |
| 90 | static int vbe_req_efi_runtime_rand(ofnode node, struct vbe_result *result) |
| 91 | { |
| 92 | return handle_random_req(node, 4, result); |
| 93 | } |
| 94 | |
| 95 | static struct vbe_req { |
| 96 | const char *compat; |
| 97 | vbe_req_func func; |
| 98 | } vbe_reqs[] = { |
| 99 | /* address space layout randomization - move the OS in memory */ |
| 100 | { "aslr-move", vbe_req_aslr_move }, |
| 101 | |
| 102 | /* provide random data for address space layout randomization */ |
| 103 | { "aslr-rand", vbe_req_aslr_rand }, |
| 104 | |
| 105 | /* provide random data for EFI-runtime-services address */ |
| 106 | { "efi-runtime-rand", vbe_req_efi_runtime_rand }, |
| 107 | |
| 108 | /* generate random data bytes to see the OS's rand generator */ |
| 109 | { "random-rand", vbe_req_random_seed }, |
| 110 | |
| 111 | }; |
| 112 | |
| 113 | static int vbe_process_request(ofnode node, struct vbe_result *result) |
| 114 | { |
| 115 | const char *compat, *req_name; |
| 116 | int i; |
| 117 | |
| 118 | compat = ofnode_read_string(node, "compatible"); |
| 119 | if (!compat) |
| 120 | return 0; |
| 121 | |
| 122 | if (strlen(compat) <= VBE_PREFIX_LEN || |
| 123 | strncmp(compat, VBE_PREFIX, VBE_PREFIX_LEN)) |
| 124 | return -EINVAL; |
| 125 | |
| 126 | req_name = compat + VBE_PREFIX_LEN; /* drop "vbe," prefix */ |
| 127 | for (i = 0; i < ARRAY_SIZE(vbe_reqs); i++) { |
| 128 | if (!strcmp(vbe_reqs[i].compat, req_name)) { |
| 129 | int ret; |
| 130 | |
| 131 | ret = vbe_reqs[i].func(node, result); |
| 132 | if (ret) |
| 133 | return log_msg_ret("req", ret); |
| 134 | return 0; |
| 135 | } |
| 136 | } |
| 137 | snprintf(result->err_str, VBE_ERR_STR_LEN, "Unknown request: %s", |
| 138 | req_name); |
| 139 | |
| 140 | return -ENOTSUPP; |
| 141 | } |
| 142 | |
| 143 | /** |
| 144 | * bootmeth_vbe_ft_fixup() - Process VBE OS requests and do device tree fixups |
| 145 | * |
| 146 | * If there are no images provided, this does nothing and returns 0. |
| 147 | * |
| 148 | * @ctx: Context for event |
| 149 | * @event: Event to process |
| 150 | * @return 0 if OK, -ve on error |
| 151 | */ |
| 152 | static int bootmeth_vbe_ft_fixup(void *ctx, struct event *event) |
| 153 | { |
| 154 | const struct event_ft_fixup *fixup = &event->data.ft_fixup; |
| 155 | const struct bootm_headers *images = fixup->images; |
| 156 | ofnode parent, dest_parent, root, node; |
| 157 | oftree fit; |
| 158 | |
| 159 | if (!images || !images->fit_hdr_os) |
| 160 | return 0; |
| 161 | |
| 162 | /* Get the image node with requests in it */ |
| 163 | log_debug("fit=%p, noffset=%d\n", images->fit_hdr_os, |
| 164 | images->fit_noffset_os); |
| 165 | fit = oftree_from_fdt(images->fit_hdr_os); |
| 166 | root = oftree_root(fit); |
| 167 | if (of_live_active()) { |
| 168 | log_warning("Cannot fix up live tree\n"); |
| 169 | return 0; |
| 170 | } |
| 171 | if (!ofnode_valid(root)) |
| 172 | return log_msg_ret("rt", -EINVAL); |
| 173 | parent = noffset_to_ofnode(root, images->fit_noffset_os); |
| 174 | if (!ofnode_valid(parent)) |
| 175 | return log_msg_ret("img", -EINVAL); |
| 176 | dest_parent = oftree_path(fixup->tree, "/chosen"); |
| 177 | if (!ofnode_valid(dest_parent)) |
| 178 | return log_msg_ret("dst", -EINVAL); |
| 179 | |
| 180 | ofnode_for_each_subnode(node, parent) { |
| 181 | const char *name = ofnode_get_name(node); |
| 182 | struct vbe_result result; |
| 183 | ofnode dest; |
| 184 | int ret; |
| 185 | |
| 186 | log_debug("copy subnode: %s\n", name); |
| 187 | ret = ofnode_add_subnode(dest_parent, name, &dest); |
| 188 | if (ret && ret != -EEXIST) |
| 189 | return log_msg_ret("add", ret); |
| 190 | ret = ofnode_copy_props(node, dest); |
| 191 | if (ret) |
| 192 | return log_msg_ret("cp", ret); |
| 193 | |
| 194 | *result.err_str = '\0'; |
| 195 | ret = vbe_process_request(dest, &result); |
| 196 | if (ret) { |
| 197 | result.errnum = ret; |
Simon Glass | ec57644 | 2022-10-20 18:23:06 -0600 | [diff] [blame] | 198 | log_warning("Failed to process VBE request %s (err=%d)\n", |
| 199 | ofnode_get_name(dest), ret); |
Simon Glass | 386d05d | 2022-10-11 09:47:18 -0600 | [diff] [blame] | 200 | if (*result.err_str) { |
| 201 | char *msg = strdup(result.err_str); |
| 202 | |
| 203 | if (!msg) |
| 204 | return log_msg_ret("msg", -ENOMEM); |
| 205 | ret = ofnode_write_string(dest, "vbe,error", |
| 206 | msg); |
| 207 | if (ret) { |
| 208 | free(msg); |
| 209 | return log_msg_ret("str", -ENOMEM); |
| 210 | } |
| 211 | } |
| 212 | if (result.errnum) { |
| 213 | ret = ofnode_write_u32(dest, "vbe,errnum", |
| 214 | result.errnum); |
| 215 | if (ret) |
| 216 | return log_msg_ret("num", -ENOMEM); |
| 217 | if (result.errnum != -ENOTSUPP) |
| 218 | return log_msg_ret("pro", |
| 219 | result.errnum); |
| 220 | if (result.errnum == -ENOTSUPP && |
| 221 | ofnode_read_bool(dest, "vbe,required")) { |
| 222 | log_err("Cannot handle required request: %s\n", |
| 223 | ofnode_get_name(dest)); |
| 224 | return log_msg_ret("req", |
| 225 | result.errnum); |
| 226 | } |
| 227 | } |
| 228 | } |
| 229 | } |
| 230 | |
| 231 | return 0; |
| 232 | } |
Simon Glass | a41134f | 2023-08-21 21:16:57 -0600 | [diff] [blame] | 233 | EVENT_SPY_FULL(EVT_FT_FIXUP, bootmeth_vbe_ft_fixup); |