1 files changed, 273 insertions, 0 deletions
diff --git a/src/shared/boot-entry.c b/src/shared/boot-entry.c
new file mode 100644
index 0000000..e726073
--- /dev/null
+++ b/src/shared/boot-entry.c
@@ -0,0 +1,273 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "boot-entry.h"
+#include "chase.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "id128-util.h"
+#include "os-util.h"
+#include "path-util.h"
+#include "string-table.h"
+#include "string-util.h"
+#include "utf8.h"
+
+bool boot_entry_token_valid(const char *p) {
+        return utf8_is_valid(p) && string_is_safe(p) && filename_is_valid(p);
+}
+
+static int entry_token_load(int rfd, const char *etc_kernel, BootEntryTokenType *type, char **token) {
+        _cleanup_free_ char *buf = NULL, *p = NULL;
+        _cleanup_fclose_ FILE *f = NULL;
+        int r;
+
+        assert(rfd >= 0 || rfd == AT_FDCWD);
+        assert(type);
+        assert(*type == BOOT_ENTRY_TOKEN_AUTO);
+        assert(token);
+
+        if (!etc_kernel)
+                return 0;
+
+        p = path_join(etc_kernel, "entry-token");
+        if (!p)
+                return log_oom();
+
+        r = chase_and_fopenat_unlocked(rfd, p, CHASE_AT_RESOLVE_IN_ROOT, "re", NULL, &f);
+        if (r == -ENOENT)
+                return 0;
+        if (r < 0)
+                return log_error_errno(r, "Failed to chase and open '%s': %m", p);
+
+        r = read_line(f, NAME_MAX, &buf);
+        if (r < 0)
+                return log_error_errno(r, "Failed to read %s: %m", p);
+
+        if (isempty(buf))
+                return 0;
+
+        if (!boot_entry_token_valid(buf)) {
+                log_debug("Invalid entry token specified in %s, ignoring.", p);
+                return 0;
+        }
+
+        *token = TAKE_PTR(buf);
+        *type = BOOT_ENTRY_TOKEN_LITERAL;
+        return 1;
+}
+
+static int entry_token_from_machine_id(sd_id128_t machine_id, BootEntryTokenType *type, char **token) {
+        char *p;
+
+        assert(type);
+        assert(IN_SET(*type, BOOT_ENTRY_TOKEN_AUTO, BOOT_ENTRY_TOKEN_MACHINE_ID));
+        assert(token);
+
+        if (sd_id128_is_null(machine_id))
+                return 0;
+
+        p = strdup(SD_ID128_TO_STRING(machine_id));
+        if (!p)
+                return log_oom();
+
+        *token = p;
+        *type = BOOT_ENTRY_TOKEN_MACHINE_ID;
+        return 1;
+}
+
+static int entry_token_from_os_release(int rfd, BootEntryTokenType *type, char **token) {
+        _cleanup_free_ char *id = NULL, *image_id = NULL;
+        int r;
+
+        assert(rfd >= 0 || rfd == AT_FDCWD);
+        assert(type);
+        assert(IN_SET(*type, BOOT_ENTRY_TOKEN_AUTO, BOOT_ENTRY_TOKEN_OS_IMAGE_ID, BOOT_ENTRY_TOKEN_OS_ID));
+        assert(token);
+
+        switch (*type) {
+        case BOOT_ENTRY_TOKEN_AUTO:
+                r = parse_os_release_at(rfd,
+                                        "IMAGE_ID", &image_id,
+                                        "ID",       &id);
+                break;
+
+        case BOOT_ENTRY_TOKEN_OS_IMAGE_ID:
+                r = parse_os_release_at(rfd, "IMAGE_ID", &image_id);
+                break;
+
+        case BOOT_ENTRY_TOKEN_OS_ID:
+                r = parse_os_release_at(rfd, "ID", &id);
+                break;
+
+        default:
+                assert_not_reached();
+        }
+        if (r == -ENOENT)
+                return 0;
+        if (r < 0)
+                return log_error_errno(r, "Failed to load /etc/os-release: %m");
+
+        if (!isempty(image_id) && boot_entry_token_valid(image_id)) {
+                *token = TAKE_PTR(image_id);
+                *type = BOOT_ENTRY_TOKEN_OS_IMAGE_ID;
+                return 1;
+        }
+
+        if (!isempty(id) && boot_entry_token_valid(id)) {
+                *token = TAKE_PTR(id);
+                *type = BOOT_ENTRY_TOKEN_OS_ID;
+                return 1;
+        }
+
+        return 0;
+}
+
+int boot_entry_token_ensure_at(
+                int rfd,
+                const char *etc_kernel,
+                sd_id128_t machine_id,
+                bool machine_id_is_random,
+                BootEntryTokenType *type,
+                char **token) {
+
+        int r;
+
+        assert(rfd >= 0 || rfd == AT_FDCWD);
+        assert(type);
+        assert(token);
+
+        if (*token)
+                return 0; /* Already set. */
+
+        switch (*type) {
+
+        case BOOT_ENTRY_TOKEN_AUTO:
+                r = entry_token_load(rfd, etc_kernel, type, token);
+                if (r != 0)
+                        return r;
+
+                if (!machine_id_is_random) {
+                        r = entry_token_from_machine_id(machine_id, type, token);
+                        if (r != 0)
+                                return r;
+                }
+
+                r = entry_token_from_os_release(rfd, type, token);
+                if (r != 0)
+                        return r;
+
+                if (machine_id_is_random) {
+                        r = entry_token_from_machine_id(machine_id, type, token);
+                        if (r != 0)
+                                return r;
+                }
+
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "No machine ID set, and /etc/os-release carries no ID=/IMAGE_ID= fields.");
+
+        case BOOT_ENTRY_TOKEN_MACHINE_ID:
+                r = entry_token_from_machine_id(machine_id, type, token);
+                if (r != 0)
+                        return r;
+
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "No machine ID set.");
+
+        case BOOT_ENTRY_TOKEN_OS_IMAGE_ID:
+                r = entry_token_from_os_release(rfd, type, token);
+                if (r != 0)
+                        return r;
+
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "IMAGE_ID= field not set in /etc/os-release.");
+
+        case BOOT_ENTRY_TOKEN_OS_ID:
+                r = entry_token_from_os_release(rfd, type, token);
+                if (r != 0)
+                        return r;
+
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "ID= field not set in /etc/os-release.");
+
+        case BOOT_ENTRY_TOKEN_LITERAL:
+                /* In this case, the token should be already set by the user input. */
+                return -EINVAL;
+
+        default:
+                assert_not_reached();
+        }
+}
+
+int boot_entry_token_ensure(
+                const char *root,
+                const char *etc_kernel,
+                sd_id128_t machine_id,
+                bool machine_id_is_random,
+                BootEntryTokenType *type,
+                char **token) {
+
+        assert(token);
+
+        if (*token)
+                return 0; /* Already set. */
+
+        _cleanup_close_ int rfd = -EBADF;
+
+        rfd = open(empty_to_root(root), O_CLOEXEC | O_DIRECTORY | O_PATH);
+        if (rfd < 0)
+                return -errno;
+
+        return boot_entry_token_ensure_at(rfd, etc_kernel, machine_id, machine_id_is_random, type, token);
+}
+
+int parse_boot_entry_token_type(const char *s, BootEntryTokenType *type, char **token) {
+        assert(s);
+        assert(type);
+        assert(token);
+
+        /*
+         * This function is intended to be used in command line parsers, to handle token that are passed in.
+         *
+         * NOTE THAT THIS WILL FREE THE PREVIOUS ARGUMENT POINTER ON SUCCESS!
+         * Hence, do not pass in uninitialized pointers.
+         */
+
+        if (streq(s, "machine-id")) {
+                *type = BOOT_ENTRY_TOKEN_MACHINE_ID;
+                *token = mfree(*token);
+                return 0;
+        }
+
+        if (streq(s, "os-image-id")) {
+                *type = BOOT_ENTRY_TOKEN_OS_IMAGE_ID;
+                *token = mfree(*token);
+                return 0;
+        }
+
+        if (streq(s, "os-id")) {
+                *type = BOOT_ENTRY_TOKEN_OS_ID;
+                *token = mfree(*token);
+                return 0;
+        }
+
+        const char *e = startswith(s, "literal:");
+        if (e) {
+                if (!boot_entry_token_valid(e))
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                               "Invalid entry token literal is specified for --entry-token=.");
+
+                *type = BOOT_ENTRY_TOKEN_LITERAL;
+                return free_and_strdup_warn(token, e);
+        }
+
+        return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                               "Unexpected parameter for --entry-token=: %s", s);
+}
+
+static const char *const boot_entry_token_type_table[] = {
+        [BOOT_ENTRY_TOKEN_MACHINE_ID]  = "machine-id",
+        [BOOT_ENTRY_TOKEN_OS_IMAGE_ID] = "os-image-id",
+        [BOOT_ENTRY_TOKEN_OS_ID]       = "os-id",
+        [BOOT_ENTRY_TOKEN_LITERAL]     = "literal",
+        [BOOT_ENTRY_TOKEN_AUTO]        = "auto",
+};
+
+DEFINE_STRING_TABLE_LOOKUP_TO_STRING(boot_entry_token_type, BootEntryTokenType);