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-rw-r--r--src/shared/efi-loader.c308
1 files changed, 308 insertions, 0 deletions
diff --git a/src/shared/efi-loader.c b/src/shared/efi-loader.c
new file mode 100644
index 0000000..1340412
--- /dev/null
+++ b/src/shared/efi-loader.c
@@ -0,0 +1,308 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "alloc-util.h"
+#include "efi-loader.h"
+#include "parse-util.h"
+#include "path-util.h"
+#include "stat-util.h"
+#include "strv.h"
+#include "utf8.h"
+
+#if ENABLE_EFI
+
+static int read_usec(const char *variable, usec_t *ret) {
+ _cleanup_free_ char *j = NULL;
+ uint64_t x = 0;
+ int r;
+
+ assert(variable);
+ assert(ret);
+
+ r = efi_get_variable_string(variable, &j);
+ if (r < 0)
+ return r;
+
+ r = safe_atou64(j, &x);
+ if (r < 0)
+ return r;
+
+ *ret = x;
+ return 0;
+}
+
+int efi_loader_get_boot_usec(usec_t *ret_firmware, usec_t *ret_loader) {
+ uint64_t x, y;
+ int r;
+
+ assert(ret_firmware);
+ assert(ret_loader);
+
+ if (!is_efi_boot())
+ return -EOPNOTSUPP;
+
+ r = read_usec(EFI_LOADER_VARIABLE(LoaderTimeInitUSec), &x);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to read LoaderTimeInitUSec: %m");
+
+ r = read_usec(EFI_LOADER_VARIABLE(LoaderTimeExecUSec), &y);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to read LoaderTimeExecUSec: %m");
+
+ if (y == 0 || y < x || y - x > USEC_PER_HOUR)
+ return log_debug_errno(SYNTHETIC_ERRNO(EIO),
+ "Bad LoaderTimeInitUSec=%"PRIu64", LoaderTimeExecUSec=%" PRIu64"; refusing.",
+ x, y);
+
+ *ret_firmware = x;
+ *ret_loader = y;
+ return 0;
+}
+
+int efi_loader_get_device_part_uuid(sd_id128_t *ret) {
+ _cleanup_free_ char *p = NULL;
+ int r;
+ unsigned parsed[16];
+
+ if (!is_efi_boot())
+ return -EOPNOTSUPP;
+
+ r = efi_get_variable_string(EFI_LOADER_VARIABLE(LoaderDevicePartUUID), &p);
+ if (r < 0)
+ return r;
+
+ if (sscanf(p, SD_ID128_UUID_FORMAT_STR,
+ &parsed[0], &parsed[1], &parsed[2], &parsed[3],
+ &parsed[4], &parsed[5], &parsed[6], &parsed[7],
+ &parsed[8], &parsed[9], &parsed[10], &parsed[11],
+ &parsed[12], &parsed[13], &parsed[14], &parsed[15]) != 16)
+ return -EIO;
+
+ if (ret)
+ for (unsigned i = 0; i < ELEMENTSOF(parsed); i++)
+ ret->bytes[i] = parsed[i];
+
+ return 0;
+}
+
+int efi_loader_get_entries(char ***ret) {
+ _cleanup_free_ char16_t *entries = NULL;
+ _cleanup_strv_free_ char **l = NULL;
+ size_t size;
+ int r;
+
+ assert(ret);
+
+ if (!is_efi_boot())
+ return -EOPNOTSUPP;
+
+ r = efi_get_variable(EFI_LOADER_VARIABLE(LoaderEntries), NULL, (void**) &entries, &size);
+ if (r < 0)
+ return r;
+
+ /* The variable contains a series of individually NUL terminated UTF-16 strings. */
+
+ for (size_t i = 0, start = 0;; i++) {
+ _cleanup_free_ char *decoded = NULL;
+ bool end;
+
+ /* Is this the end of the variable's data? */
+ end = i * sizeof(char16_t) >= size;
+
+ /* Are we in the middle of a string? (i.e. not at the end of the variable, nor at a NUL terminator?) If
+ * so, let's go to the next entry. */
+ if (!end && entries[i] != 0)
+ continue;
+
+ /* We reached the end of a string, let's decode it into UTF-8 */
+ decoded = utf16_to_utf8(entries + start, (i - start) * sizeof(char16_t));
+ if (!decoded)
+ return -ENOMEM;
+
+ if (efi_loader_entry_name_valid(decoded)) {
+ r = strv_consume(&l, TAKE_PTR(decoded));
+ if (r < 0)
+ return r;
+ } else
+ log_debug("Ignoring invalid loader entry '%s'.", decoded);
+
+ /* We reached the end of the variable */
+ if (end)
+ break;
+
+ /* Continue after the NUL byte */
+ start = i + 1;
+ }
+
+ *ret = TAKE_PTR(l);
+ return 0;
+}
+
+int efi_loader_get_features(uint64_t *ret) {
+ _cleanup_free_ void *v = NULL;
+ size_t s;
+ int r;
+
+ assert(ret);
+
+ if (!is_efi_boot()) {
+ *ret = 0;
+ return 0;
+ }
+
+ r = efi_get_variable(EFI_LOADER_VARIABLE(LoaderFeatures), NULL, &v, &s);
+ if (r == -ENOENT) {
+ _cleanup_free_ char *info = NULL;
+
+ /* The new (v240+) LoaderFeatures variable is not supported, let's see if it's systemd-boot at all */
+ r = efi_get_variable_string(EFI_LOADER_VARIABLE(LoaderInfo), &info);
+ if (r < 0) {
+ if (r != -ENOENT)
+ return r;
+
+ /* Variable not set, definitely means not systemd-boot */
+
+ } else if (first_word(info, "systemd-boot")) {
+
+ /* An older systemd-boot version. Let's hardcode the feature set, since it was pretty
+ * static in all its versions. */
+
+ *ret = EFI_LOADER_FEATURE_CONFIG_TIMEOUT |
+ EFI_LOADER_FEATURE_ENTRY_DEFAULT |
+ EFI_LOADER_FEATURE_ENTRY_ONESHOT;
+
+ return 0;
+ }
+
+ /* No features supported */
+ *ret = 0;
+ return 0;
+ }
+ if (r < 0)
+ return r;
+
+ if (s != sizeof(uint64_t))
+ return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+ "LoaderFeatures EFI variable doesn't have the right size.");
+
+ memcpy(ret, v, sizeof(uint64_t));
+ return 0;
+}
+
+int efi_stub_get_features(uint64_t *ret) {
+ _cleanup_free_ void *v = NULL;
+ size_t s;
+ int r;
+
+ assert(ret);
+
+ if (!is_efi_boot()) {
+ *ret = 0;
+ return 0;
+ }
+
+ r = efi_get_variable(EFI_LOADER_VARIABLE(StubFeatures), NULL, &v, &s);
+ if (r == -ENOENT) {
+ _cleanup_free_ char *info = NULL;
+
+ /* The new (v252+) StubFeatures variable is not supported, let's see if it's systemd-stub at all */
+ r = efi_get_variable_string(EFI_LOADER_VARIABLE(StubInfo), &info);
+ if (r < 0) {
+ if (r != -ENOENT)
+ return r;
+
+ /* Variable not set, definitely means not systemd-stub */
+
+ } else if (first_word(info, "systemd-stub")) {
+
+ /* An older systemd-stub version. Let's hardcode the feature set, since it was pretty
+ * static in all its versions. */
+
+ *ret = EFI_STUB_FEATURE_REPORT_BOOT_PARTITION;
+ return 0;
+ }
+
+ /* No features supported */
+ *ret = 0;
+ return 0;
+ }
+ if (r < 0)
+ return r;
+
+ if (s != sizeof(uint64_t))
+ return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+ "StubFeatures EFI variable doesn't have the right size.");
+
+ memcpy(ret, v, sizeof(uint64_t));
+ return 0;
+}
+
+int efi_loader_get_config_timeout_one_shot(usec_t *ret) {
+ _cleanup_free_ char *v = NULL;
+ static struct stat cache_stat = {};
+ struct stat new_stat;
+ static usec_t cache;
+ uint64_t sec;
+ int r;
+
+ assert(ret);
+
+ /* stat() the EFI variable, to see if the mtime changed. If it did, we need to cache again. */
+ if (stat(EFIVAR_PATH(EFI_LOADER_VARIABLE(LoaderConfigTimeoutOneShot)), &new_stat) < 0)
+ return -errno;
+
+ if (stat_inode_unmodified(&new_stat, &cache_stat)) {
+ *ret = cache;
+ return 0;
+ }
+
+ r = efi_get_variable_string(EFI_LOADER_VARIABLE(LoaderConfigTimeoutOneShot), &v);
+ if (r < 0)
+ return r;
+
+ r = safe_atou64(v, &sec);
+ if (r < 0)
+ return r;
+ if (sec > USEC_INFINITY / USEC_PER_SEC)
+ return -ERANGE;
+
+ cache_stat = new_stat;
+ *ret = cache = sec * USEC_PER_SEC; /* return in µs */
+ return 0;
+}
+
+int efi_loader_update_entry_one_shot_cache(char **cache, struct stat *cache_stat) {
+ _cleanup_free_ char *v = NULL;
+ struct stat new_stat;
+ int r;
+
+ assert(cache);
+ assert(cache_stat);
+
+ /* stat() the EFI variable, to see if the mtime changed. If it did we need to cache again. */
+ if (stat(EFIVAR_PATH(EFI_LOADER_VARIABLE(LoaderEntryOneShot)), &new_stat) < 0)
+ return -errno;
+
+ if (stat_inode_unmodified(&new_stat, cache_stat))
+ return 0;
+
+ r = efi_get_variable_string(EFI_LOADER_VARIABLE(LoaderEntryOneShot), &v);
+ if (r < 0)
+ return r;
+
+ if (!efi_loader_entry_name_valid(v))
+ return -EINVAL;
+
+ *cache_stat = new_stat;
+ free_and_replace(*cache, v);
+
+ return 0;
+}
+
+#endif
+
+bool efi_loader_entry_name_valid(const char *s) {
+ if (!filename_is_valid(s)) /* Make sure entry names fit in filenames */
+ return false;
+
+ return in_charset(s, ALPHANUMERICAL "+-_.");
+}
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