creds-util: add common helper for determinign global boot credentials path

It's very useful being able to determine the directory where to write
global boot credentials to, that are picked up by all kernels.

1 files changed, 51 insertions, 0 deletions

diff --git a/src/shared/creds-util.c b/src/shared/creds-util.c
index eaf772bff2..e99477997a 100644
--- a/src/shared/creds-util.c
+++ b/src/shared/creds-util.c
@@ -19,6 +19,7 @@
 #include "env-util.h"
 #include "fd-util.h"
 #include "fileio.h"
+#include "find-esp.h"
 #include "format-util.h"
 #include "fs-util.h"
 #include "io-util.h"
@@ -1657,6 +1658,56 @@ int ipc_decrypt_credential(const char *validate_name, usec_t validate_timestamp,
         return 0;
 }
 
+int get_global_boot_credentials_path(char **ret) {
+        _cleanup_free_ char *path = NULL;
+        int r;
+
+        assert(ret);
+
+        /* Determines where to put global boot credentials in. Returns the path to the "/loader/credentials/"
+         * directory below the XBOOTLDR or ESP partition. Any credentials placed in this directory can be
+         * picked up later in the initrd. */
+
+        r = find_xbootldr_and_warn(
+                        /* root= */ NULL,
+                        /* path= */ NULL,
+                        /* unprivileged_mode= */ false,
+                        &path,
+                        /* ret_uuid= */ NULL,
+                        /* ret_devid= */ NULL);
+        if (r < 0) {
+                if (r != -ENOKEY)
+                        return log_error_errno(r, "Failed to find XBOOTLDR partition: %m");
+
+                r = find_esp_and_warn(
+                                /* root= */ NULL,
+                                /* path= */ NULL,
+                                /* unprivileged_mode= */ false,
+                                &path,
+                                /* ret_part= */ NULL,
+                                /* ret_pstart= */ NULL,
+                                /* ret_psize= */ NULL,
+                                /* ret_uuid= */ NULL,
+                                /* ret_devid= */ NULL);
+                if (r < 0) {
+                        if (r != -ENOKEY)
+                                return log_error_errno(r, "Failed to find ESP partition: %m");
+
+                        *ret = NULL;
+                        return 0; /* not found! */
+                }
+        }
+
+        _cleanup_free_ char *joined = path_join(path, "loader/credentials");
+        if (!joined)
+                return log_oom();
+
+        log_debug("Determined global boot credentials path as: %s", joined);
+
+        *ret = TAKE_PTR(joined);
+        return 1; /* found! */
+}
+
 static int pick_up_credential_one(
                 int credential_dir_fd,
                 const char *credential_name,