#include "loader-features.h"
#include "measure.h"
#include "pe.h"
+#include "random-seed.h"
#include "shim.h"
#include "util.h"
BOOLEAN force_menu;
UINTN console_mode;
enum console_mode_change_type console_mode_change;
+ RandomSeedMode random_seed_mode;
} Config;
static VOID cursor_left(UINTN *cursor, UINTN *first) {
Print(L"editor: %s\n", yes_no(config->editor));
Print(L"auto-entries: %s\n", yes_no(config->auto_entries));
Print(L"auto-firmware: %s\n", yes_no(config->auto_firmware));
+
+ switch (config->random_seed_mode) {
+ case RANDOM_SEED_OFF:
+ Print(L"random-seed-mode: off\n");
+ break;
+ case RANDOM_SEED_WITH_SYSTEM_TOKEN:
+ Print(L"random-seed-node: with-system-token\n");
+ break;
+ case RANDOM_SEED_ALWAYS:
+ Print(L"random-seed-node: always\n");
+ break;
+ default:
+ ;
+ }
+
Print(L"\n");
Print(L"config entry count: %d\n", config->entry_count);
continue;
}
+
+ if (strcmpa((CHAR8*) "random-seed-mode", key) == 0) {
+ if (strcmpa((CHAR8*) "off", value) == 0)
+ config->random_seed_mode = RANDOM_SEED_OFF;
+ else if (strcmpa((CHAR8*) "with-system-token", value) == 0)
+ config->random_seed_mode = RANDOM_SEED_WITH_SYSTEM_TOKEN;
+ else if (strcmpa((CHAR8*) "always", value) == 0)
+ config->random_seed_mode = RANDOM_SEED_ALWAYS;
+ else {
+ BOOLEAN on;
+
+ if (EFI_ERROR(parse_boolean(value, &on)))
+ continue;
+
+ config->random_seed_mode = on ? RANDOM_SEED_ALWAYS : RANDOM_SEED_OFF;
+ }
+ }
}
}
.editor = TRUE,
.auto_entries = TRUE,
.auto_firmware = TRUE,
+ .random_seed_mode = RANDOM_SEED_WITH_SYSTEM_TOKEN,
};
err = file_read(root_dir, L"\\loader\\loader.conf", 0, 0, &content, NULL);
EFI_LOADER_FEATURE_ENTRY_ONESHOT |
EFI_LOADER_FEATURE_BOOT_COUNTING |
EFI_LOADER_FEATURE_XBOOTLDR |
+ EFI_LOADER_FEATURE_RANDOM_SEED |
0;
_cleanup_freepool_ CHAR16 *infostr = NULL, *typestr = NULL;
config_entry_bump_counters(entry, root_dir);
- /* export the selected boot entry to the system */
- efivar_set(L"LoaderEntrySelected", entry->id, FALSE);
+ /* Export the selected boot entry to the system */
+ (VOID) efivar_set(L"LoaderEntrySelected", entry->id, FALSE);
+
+ /* Optionally, read a random seed off the ESP and pass it to the OS */
+ (VOID) process_random_seed(root_dir, config.random_seed_mode);
uefi_call_wrapper(BS->SetWatchdogTimer, 4, 5 * 60, 0x10000, 0, NULL);
err = image_start(image, &config, entry);
--- /dev/null
+#include <efi.h>
+#include <efilib.h>
+
+#include "random-seed.h"
+#include "sha256.h"
+#include "util.h"
+#include "shim.h"
+
+#define RANDOM_MAX_SIZE_MIN (32U)
+#define RANDOM_MAX_SIZE_MAX (32U*1024U)
+
+static const EFI_GUID rng_protocol_guid = EFI_RNG_PROTOCOL_GUID;
+
+/* SHA256 gives us 256/8=32 bytes */
+#define HASH_VALUE_SIZE 32
+
+static EFI_STATUS acquire_rng(UINTN size, VOID **ret) {
+ _cleanup_freepool_ VOID *data = NULL;
+ EFI_RNG_PROTOCOL *rng;
+ EFI_STATUS err;
+
+ /* Try to acquire the specified number of bytes from the UEFI RNG */
+
+ err = LibLocateProtocol((EFI_GUID*) &rng_protocol_guid, (VOID**) &rng);
+ if (EFI_ERROR(err)) {
+ Print(L"Failed to acquire RNG protocol: %r\n", err);
+ return err;
+ }
+ if (!rng) {
+ /* Print(L"RNG protocol not available.\n"); */
+ return EFI_UNSUPPORTED;
+ }
+
+ data = AllocatePool(size);
+ if (!data)
+ return log_oom();
+
+ err = uefi_call_wrapper(rng->GetRNG, 3, rng, NULL, size, data);
+ if (EFI_ERROR(err)) {
+ Print(L"Failed to acquire RNG data: %r\n", err);
+ return err;
+ }
+
+ *ret = TAKE_PTR(data);
+ return EFI_SUCCESS;
+}
+
+static VOID hash_once(
+ const VOID *old_seed,
+ const VOID *rng,
+ UINTN size,
+ const VOID *system_token,
+ UINTN system_token_size,
+ UINTN counter,
+ UINT8 ret[static HASH_VALUE_SIZE]) {
+
+ /* This hashes together:
+ *
+ * 1. The contents of the old seed file
+ * 2. Some random data acquired from the UEFI RNG (optional)
+ * 3. Some 'system token' the installer installed as EFI variable (optional)
+ * 4. A counter value
+ *
+ * And writes the result to the specified buffer.
+ */
+
+ struct sha256_ctx hash;
+
+ sha256_init_ctx(&hash);
+ sha256_process_bytes(old_seed, size, &hash);
+ if (rng)
+ sha256_process_bytes(rng, size, &hash);
+ if (system_token_size > 0)
+ sha256_process_bytes(system_token, system_token_size, &hash);
+ sha256_process_bytes(&counter, sizeof(counter), &hash);
+ sha256_finish_ctx(&hash, ret);
+}
+
+static EFI_STATUS hash_many(
+ const VOID *old_seed,
+ const VOID *rng,
+ UINTN size,
+ const VOID *system_token,
+ UINTN system_token_size,
+ UINTN counter_start,
+ UINTN n,
+ VOID **ret) {
+
+ _cleanup_freepool_ VOID *output = NULL;
+ UINTN i;
+
+ /* Hashes the specified parameters in counter mode, generating n hash values, with the counter in the
+ * range counter_start…counter_start+n-1. */
+
+ output = AllocatePool(n * HASH_VALUE_SIZE);
+ if (!output)
+ return log_oom();
+
+ for (i = 0; i < n; i++)
+ hash_once(old_seed, rng, size,
+ system_token, system_token_size,
+ counter_start + i,
+ (UINT8*) output + (i * HASH_VALUE_SIZE));
+
+ *ret = TAKE_PTR(output);
+ return EFI_SUCCESS;
+}
+
+static EFI_STATUS mangle_random_seed(
+ const VOID *old_seed,
+ const VOID *rng,
+ UINTN size,
+ const VOID *system_token,
+ UINTN system_token_size,
+ VOID **ret_new_seed,
+ VOID **ret_for_kernel) {
+
+ _cleanup_freepool_ VOID *new_seed = NULL, *for_kernel = NULL;
+ EFI_STATUS err;
+ UINTN n;
+
+ /* This takes the old seed file contents, an (optional) random number acquired from the UEFI RNG, an
+ * (optional) system 'token' installed once by the OS installer in an EFI variable, and hashes them
+ * together in counter mode, generating a new seed (to replace the file on disk) and the seed for the
+ * kernel. To keep things simple, the new seed and kernel data have the same size as the old seed and
+ * RNG data. */
+
+ n = (size + HASH_VALUE_SIZE - 1) / HASH_VALUE_SIZE;
+
+ /* Begin hashing in counter mode at counter 0 for the new seed for the disk */
+ err = hash_many(old_seed, rng, size, system_token, system_token_size, 0, n, &new_seed);
+ if (EFI_ERROR(err))
+ return err;
+
+ /* Continue counting at 'n' for the seed for the kernel */
+ err = hash_many(old_seed, rng, size, system_token, system_token_size, n, n, &for_kernel);
+ if (EFI_ERROR(err))
+ return err;
+
+ *ret_new_seed = TAKE_PTR(new_seed);
+ *ret_for_kernel = TAKE_PTR(for_kernel);
+
+ return EFI_SUCCESS;
+}
+
+EFI_STATUS acquire_system_token(VOID **ret, UINTN *ret_size) {
+ _cleanup_freepool_ CHAR8 *data = NULL;
+ EFI_STATUS err;
+ UINTN size;
+
+ err = efivar_get_raw(&loader_guid, L"LoaderSystemToken", &data, &size);
+ if (EFI_ERROR(err)) {
+ if (err != EFI_NOT_FOUND)
+ Print(L"Failed to read LoaderSystemToken EFI variable: %r", err);
+ return err;
+ }
+
+ if (size <= 0) {
+ Print(L"System token too short, ignoring.");
+ return EFI_NOT_FOUND;
+ }
+
+ *ret = TAKE_PTR(data);
+ *ret_size = size;
+
+ return EFI_SUCCESS;
+}
+
+static VOID validate_sha256(void) {
+
+#ifndef __OPTIMIZE__
+ /* Let's validate our SHA256 implementation. We stole it from glibc, and converted it to UEFI
+ * style. We better check whether it does the right stuff. We use the simpler test vectors from the
+ * SHA spec. Note that we strip this out in optimization builds. */
+
+ static const struct {
+ const char *string;
+ uint8_t hash[HASH_VALUE_SIZE];
+ } array[] = {
+ { "abc",
+ { 0xba, 0x78, 0x16, 0xbf, 0x8f, 0x01, 0xcf, 0xea,
+ 0x41, 0x41, 0x40, 0xde, 0x5d, 0xae, 0x22, 0x23,
+ 0xb0, 0x03, 0x61, 0xa3, 0x96, 0x17, 0x7a, 0x9c,
+ 0xb4, 0x10, 0xff, 0x61, 0xf2, 0x00, 0x15, 0xad }},
+
+ { "",
+ { 0xe3, 0xb0, 0xc4, 0x42, 0x98, 0xfc, 0x1c, 0x14,
+ 0x9a, 0xfb, 0xf4, 0xc8, 0x99, 0x6f, 0xb9, 0x24,
+ 0x27, 0xae, 0x41, 0xe4, 0x64, 0x9b, 0x93, 0x4c,
+ 0xa4, 0x95, 0x99, 0x1b, 0x78, 0x52, 0xb8, 0x55 }},
+
+ { "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq",
+ { 0x24, 0x8d, 0x6a, 0x61, 0xd2, 0x06, 0x38, 0xb8,
+ 0xe5, 0xc0, 0x26, 0x93, 0x0c, 0x3e, 0x60, 0x39,
+ 0xa3, 0x3c, 0xe4, 0x59, 0x64, 0xff, 0x21, 0x67,
+ 0xf6, 0xec, 0xed, 0xd4, 0x19, 0xdb, 0x06, 0xc1 }},
+
+ { "abcdefghbcdefghicdefghijdefghijkefghijklfghijklmghijklmnhijklmnoijklmnopjklmnopqklmnopqrlmnopqrsmnopqrstnopqrstu",
+ { 0xcf, 0x5b, 0x16, 0xa7, 0x78, 0xaf, 0x83, 0x80,
+ 0x03, 0x6c, 0xe5, 0x9e, 0x7b, 0x04, 0x92, 0x37,
+ 0x0b, 0x24, 0x9b, 0x11, 0xe8, 0xf0, 0x7a, 0x51,
+ 0xaf, 0xac, 0x45, 0x03, 0x7a, 0xfe, 0xe9, 0xd1 }},
+ };
+
+ UINTN i;
+
+ for (i = 0; i < ELEMENTSOF(array); i++) {
+ struct sha256_ctx hash;
+ uint8_t result[HASH_VALUE_SIZE];
+
+ sha256_init_ctx(&hash);
+ sha256_process_bytes(array[i].string, strlena((const CHAR8*) array[i].string), &hash);
+ sha256_finish_ctx(&hash, result);
+
+ if (CompareMem(result, array[i].hash, HASH_VALUE_SIZE) != 0) {
+ Print(L"SHA256 failed validation.\n");
+ uefi_call_wrapper(BS->Stall, 1, 120 * 1000 * 1000);
+ return;
+ }
+ }
+
+ Print(L"SHA256 validated\n");
+#endif
+}
+
+EFI_STATUS process_random_seed(EFI_FILE *root_dir, RandomSeedMode mode) {
+ _cleanup_freepool_ VOID *seed = NULL, *new_seed = NULL, *rng = NULL, *for_kernel = NULL, *system_token = NULL;
+ _cleanup_(FileHandleClosep) EFI_FILE_HANDLE handle = NULL;
+ UINTN size, rsize, wsize, system_token_size = 0;
+ _cleanup_freepool_ EFI_FILE_INFO *info = NULL;
+ EFI_STATUS err;
+
+ validate_sha256();
+
+ if (mode == RANDOM_SEED_OFF) {
+ /* Print(L"Random seed handling turned off.\n"); */
+ return EFI_NOT_FOUND;
+ }
+
+ /* Let's better be safe than sorry, and for now disable this logic in SecureBoot mode, so that we
+ * don't credit a random seed that is not authenticated. */
+ if (secure_boot_enabled()) {
+ /* Print(L"Not loading random seed, because we are in SecureBoot mode.\n"); */
+ return EFI_NOT_FOUND;
+ }
+
+ /* Get some system specific seed that the installer might have placed in an EFI variable. We include
+ * it in our hash. This is protection against golden master image sloppiness, and it remains on the
+ * system, even when disk images are duplicated or swapped out. */
+ err = acquire_system_token(&system_token, &system_token_size);
+ if (mode != RANDOM_SEED_ALWAYS) {
+ /* if (err == EFI_NOT_FOUND) */
+ /* Print(L"Not loading random seed, because no system token is set.\n"); */
+ if (EFI_ERROR(err))
+ return err; /* in all other error cases we already logged */
+ }
+
+ err = uefi_call_wrapper(root_dir->Open, 5, root_dir, &handle, L"\\loader\\random-seed", EFI_FILE_MODE_READ|EFI_FILE_MODE_WRITE, 0ULL);
+ if (EFI_ERROR(err)) {
+ if (err != EFI_NOT_FOUND)
+ Print(L"Failed to open random seed file: %r\n", err);
+ /* else */
+ /* Print(L"Not loading random seed, because there is none.\n"); */
+
+ return err;
+ }
+
+ info = LibFileInfo(handle);
+ if (!info)
+ return log_oom();
+
+ size = info->FileSize;
+ if (size < RANDOM_MAX_SIZE_MIN) {
+ Print(L"Random seed file is too short?\n");
+ return EFI_INVALID_PARAMETER;
+ }
+
+ if (size > RANDOM_MAX_SIZE_MAX) {
+ Print(L"Random seed file is too large?\n");
+ return EFI_INVALID_PARAMETER;
+ }
+
+ seed = AllocatePool(size);
+ if (!seed)
+ return log_oom();
+
+ rsize = size;
+ err = uefi_call_wrapper(handle->Read, 3, handle, &rsize, seed);
+ if (EFI_ERROR(err)) {
+ Print(L"Failed to read random seed file: %r\n", err);
+ return err;
+ }
+ if (rsize != size) {
+ Print(L"Short read on random seed file\n");
+ return EFI_PROTOCOL_ERROR;
+ }
+
+ err = uefi_call_wrapper(handle->SetPosition, 2, handle, 0);
+ if (EFI_ERROR(err)) {
+ Print(L"Failed to seek to beginning of random seed file: %r\n", err);
+ return err;
+ }
+
+ /* Request some random data from the UEFI RNG. We don't need this to work safely, but it's a good
+ * idea to use it because it helps us for cases where users mistakenly include a random seed in
+ * golden master images that are replicated many times. */
+ (VOID) acquire_rng(size, &rng); /* It's fine if this fails */
+
+ /* Calculate new random seed for the disk and what to pass to the kernel */
+ err = mangle_random_seed(seed, rng, size, system_token, system_token_size, &new_seed, &for_kernel);
+ if (EFI_ERROR(err))
+ return err;
+
+ /* Update the random seed on disk before we use it */
+ wsize = size;
+ err = uefi_call_wrapper(handle->Write, 3, handle, &wsize, new_seed);
+ if (EFI_ERROR(err)) {
+ Print(L"Failed to write random seed file: %r\n", err);
+ return err;
+ }
+ if (wsize != size) {
+ Print(L"Short write on random seed file\n");
+ return EFI_PROTOCOL_ERROR;
+ }
+
+ err = uefi_call_wrapper(handle->Flush, 1, handle);
+ if (EFI_ERROR(err)) {
+ Print(L"Failed to flush random seed file: %r\n");
+ return err;
+ }
+
+ /* We are good to go */
+ err = efivar_set_raw(&loader_guid, L"LoaderRandomSeed", for_kernel, size, FALSE);
+ if (EFI_ERROR(err)) {
+ Print(L"Failed to write random seed to EFI variable: %r\n", err);
+ return err;
+ }
+
+ return EFI_SUCCESS;
+}
projects / thirdparty / systemd.git / commitdiff
