sysroot: Support boot counting for boot entries

Add support for boot counting for bootloader entries [1]. The boot counting data is stored in the name of the boot loader entry. A boot loader entry file name may contain a plus (+) followed by a number. This may optionally be followed by a minus (-) followed by a second number. The dot (.) and file name suffix (conf or efi) must immediately follow. All "pending" entries (in the middle of boot counting) are automatically removed during creation of new boot entries for new deployments. The feature is enabled with --enable_boot_count autoconf option. Testing: $ ostree admin deploy 91fc19319be9e79d07159303dff125f40f10e5c25614630dcbed23d95e36f907 Copying /etc changes: 2 modified, 3 removed, 4 added bootfs is sufficient for calculated new size: 0 bytes Transaction complete; bootconfig swap: yes; bootversion: boot.0.1, deployment count change: 1 $ ls /boot/loader/entries ostree-1+3.conf ostree-2+3.conf [1] https://uapi-group.org/specifications/specs/boot_loader_specification/#boot-counting Signed-off-by: Igor Opaniuk <[email protected]> configure option
ostreedev · Oct 16, 2024 · 8ea23c7 · 8ea23c7
1 parent f7018d8
commit 8ea23c7
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diff --git a/configure.ac b/configure.ac
@@ -362,6 +362,14 @@ AS_IF([test "$enable_man_html" = yes && test "$enable_man" = no], [
 ])
 AM_CONDITIONAL(ENABLE_MAN_HTML, test "$enable_man_html" = yes)
 
+AC_ARG_ENABLE(boot-count,
+              AS_HELP_STRING([--enable-boot-count],
+                             [Enable boot counting for boot entries (default: no)]),,
+              enable_boot_count=no)
+AS_IF([ test "$enable_boot_count" != no], [
+  AC_DEFINE([ENABLE_BOOT_COUNT], 1, [Define if boot counting is enabled])
+])
+
 AC_ARG_WITH(libarchive,
 	    AS_HELP_STRING([--without-libarchive], [Do not use libarchive]),
 	    :, with_libarchive=maybe)
@@ -705,6 +713,7 @@ echo "
     man pages (xsltproc):                         $enable_man
     api docs (gtk-doc):                           $enable_gtk_doc
     installed tests:                              $enable_installed_tests
+    boot counting for boot entries:               $enable_boot_count
     gjs-based tests:                              $have_gjs
     dracut:                                       $with_dracut
     mkinitcpio:                                   $with_mkinitcpio

diff --git a/src/libostree/ostree-deployment.c b/src/libostree/ostree-deployment.c
@@ -398,6 +398,25 @@ ostree_deployment_get_origin_relpath (OstreeDeployment *self)
                           ostree_deployment_get_deployserial (self));
 }
 
+
+/**
+ * ostree_deployment_get_boot_tries_relpath:
+ * @self: A deployment
+ *
+ * Note this function only returns a *relative* path - if you want to
+ * access, it, you must either use fd-relative api such as openat(),
+ * or concatenate it with the full ostree_sysroot_get_path().
+ *
+ * Returns: (not nullable) (transfer full): Path to deployment root directory, relative to sysroot
+ */
+char *
+ostree_deployment_get_boot_tries_relpath (OstreeDeployment *self)
+{
+  return g_strdup_printf ("ostree/deploy/%s/deploy/%s.%d/etc/kernel/tries",
+                          ostree_deployment_get_osname (self), ostree_deployment_get_csum (self),
+                          ostree_deployment_get_deployserial (self));
+}
+
 /**
  * ostree_deployment_unlocked_state_to_string:
  *

diff --git a/src/libostree/ostree-deployment.h b/src/libostree/ostree-deployment.h
@@ -93,6 +93,9 @@ OstreeDeployment *ostree_deployment_clone (OstreeDeployment *self);
 _OSTREE_PUBLIC
 char *ostree_deployment_get_origin_relpath (OstreeDeployment *self);
 
+_OSTREE_PUBLIC
+char *ostree_deployment_get_boot_tries_relpath (OstreeDeployment *self);
+
 typedef enum
 {
   OSTREE_DEPLOYMENT_UNLOCKED_NONE,

diff --git a/src/libostree/ostree-sysroot-deploy.c b/src/libostree/ostree-sysroot-deploy.c
@@ -1776,13 +1776,13 @@ parse_os_release (const char *contents, const char *split)
   return ret;
 }
 
-/* Generate the filename we will use in /boot/loader/entries for this deployment.
+/* Generate the entry name we will use in /boot/loader/entries for this deployment.
  * The provided n_deployments should be the total number of target deployments (which
  * might be different from the cached value in the sysroot).
  */
 static char *
-bootloader_entry_filename (OstreeSysroot *sysroot, guint n_deployments,
-                           OstreeDeployment *deployment)
+bootloader_entry_name (OstreeSysroot *sysroot, guint n_deployments,
+                       OstreeDeployment *deployment)
 {
   guint index = n_deployments - ostree_deployment_get_index (deployment);
   // Allow opt-out to dropping the stateroot in case of compatibility issues.
@@ -1792,14 +1792,78 @@ bootloader_entry_filename (OstreeSysroot *sysroot, guint n_deployments,
   if (use_old_naming)
     {
       const char *stateroot = ostree_deployment_get_osname (deployment);
-      return g_strdup_printf ("ostree-%d-%s.conf", index, stateroot);
+      return g_strdup_printf ("ostree-%d-%s", index, stateroot);
     }
   else
     {
-      return g_strdup_printf ("ostree-%d.conf", index);
+      return g_strdup_printf ("ostree-%d", index);
     }
 }
 
+#ifdef ENABLE_BOOT_COUNT
+
+#define BOOT_COUNT_MAX_RETRIES 3
+
+static gint
+bootloader_get_max_boot_tries (OstreeSysroot *self, OstreeDeployment *deployment,
+                               GCancellable *cancellable, GError **error)
+{
+  g_autofree char *tries_file_path = ostree_deployment_get_boot_tries_relpath (deployment);
+
+  glnx_autofd int fd = -1;
+  if (!ot_openat_ignore_enoent (self->sysroot_fd, tries_file_path, &fd, error))
+    return BOOT_COUNT_MAX_RETRIES;
+  if (fd >= 0)
+    {
+      g_autofree char *origin_contents = glnx_fd_readall_utf8 (fd, NULL, cancellable, error);
+      if (!origin_contents)
+        return BOOT_COUNT_MAX_RETRIES;
+
+      return atoi(origin_contents);
+    }
+
+    return BOOT_COUNT_MAX_RETRIES;
+}
+
+/* Drop all temporary entries in /boot/loader/entries for this deployment,
+ * which were created during automatic boot assesment
+ * https://uapi-group.org/specifications/specs/boot_loader_specification/#boot-counting
+ */
+static gboolean
+bootloader_remove_tmp_entries (int dfd, const char *entry_name, gint max_tries, GCancellable *cancellable,
+                               GError **error)
+{
+  g_auto(GLnxDirFdIterator) dfd_iter = { 0, };
+  g_autofree char *entry_name_init = g_strdup_printf ("%s+%d", entry_name, max_tries);
+
+  if (!glnx_dirfd_iterator_init_at (dfd, ".", FALSE, &dfd_iter, error))
+    return FALSE;
+
+  while (TRUE)
+    {
+      struct dirent *dent = NULL;
+
+      if (!glnx_dirfd_iterator_next_dent_ensure_dtype (&dfd_iter, &dent, cancellable, error))
+        return FALSE;
+      if (dent == NULL)
+        break;
+
+      /* Don't remove default boot entry (with +3 suffix) */
+      if (g_str_has_prefix (dent->d_name, entry_name_init))
+        continue;
+
+      if (g_str_has_prefix (dent->d_name, entry_name))
+        {
+          if (!glnx_shutil_rm_rf_at (dfd_iter.fd, dent->d_name, cancellable, error))
+            return FALSE;
+        }
+
+    }
+
+    return TRUE;
+}
+#endif
+
 /* Given @deployment, prepare it to be booted; basically copying its
  * kernel/initramfs into /boot/ostree (if needed) and writing out an entry in
  * /boot/loader/entries.
@@ -1834,7 +1898,7 @@ install_deployment_kernel (OstreeSysroot *sysroot, int new_bootversion,
   const char *bootcsum = ostree_deployment_get_bootcsum (deployment);
   g_autofree char *bootcsumdir = g_strdup_printf ("ostree/%s-%s", osname, bootcsum);
   g_autofree char *bootconfdir = g_strdup_printf ("loader.%d/entries", new_bootversion);
-  g_autofree char *bootconf_name = bootloader_entry_filename (sysroot, n_deployments, deployment);
+  g_autofree char *bootconf_name = bootloader_entry_name (sysroot, n_deployments, deployment);
 
   if (!glnx_shutil_mkdir_p_at (sysroot->boot_fd, bootcsumdir, 0775, cancellable, error))
     return FALSE;
@@ -2145,9 +2209,18 @@ install_deployment_kernel (OstreeSysroot *sysroot, int new_bootversion,
   glnx_autofd int bootconf_dfd = -1;
   if (!glnx_opendirat (sysroot->boot_fd, bootconfdir, TRUE, &bootconf_dfd, error))
     return FALSE;
+#ifdef ENABLE_BOOT_COUNT
+  gint max_tries = bootloader_get_max_boot_tries (sysroot, deployment, cancellable, error);
+  g_autofree char *bootconf_filename = g_strdup_printf ("%s+%d.conf", bootconf_name, max_tries);
+
+  if (!bootloader_remove_tmp_entries(bootconf_dfd, bootconf_name, max_tries, cancellable, error))
+    return FALSE;
+#else
+  g_autofree char *bootconf_filename = g_strdup_printf ("%s.conf", bootconf_name);
+#endif
 
   if (!ostree_bootconfig_parser_write_at (ostree_deployment_get_bootconfig (deployment),
-                                          bootconf_dfd, bootconf_name, cancellable, error))
+                                          bootconf_dfd, bootconf_filename, cancellable, error))
     return FALSE;
 
   return TRUE;
@@ -4176,14 +4249,22 @@ ostree_sysroot_deployment_set_kargs_in_place (OstreeSysroot *self, OstreeDeploym
       ostree_bootconfig_parser_set (new_bootconfig, "options", kargs_str);
 
       g_autofree char *bootconf_name
-          = bootloader_entry_filename (self, self->deployments->len, deployment);
+          = bootloader_entry_name (self, self->deployments->len, deployment);
 
       g_autofree char *bootconfdir = g_strdup_printf ("loader.%d/entries", self->bootversion);
       glnx_autofd int bootconf_dfd = -1;
       if (!glnx_opendirat (self->boot_fd, bootconfdir, TRUE, &bootconf_dfd, error))
         return FALSE;
+#ifdef ENABLE_BOOT_COUNT
+      gint max_tries = bootloader_get_max_boot_tries (self, deployment, cancellable, error);
+      g_autofree char *bootconf_filename = g_strdup_printf ("%s+%d.conf", bootconf_name, max_tries);
 
-      if (!ostree_bootconfig_parser_write_at (new_bootconfig, bootconf_dfd, bootconf_name,
+      if (!bootloader_remove_tmp_entries(bootconf_dfd, bootconf_name, max_tries, cancellable, error))
+        return FALSE;
+#else
+      g_autofree char *bootconf_filename = g_strdup_printf ("%s.conf", bootconf_name);
+#endif
+      if (!ostree_bootconfig_parser_write_at (new_bootconfig, bootconf_dfd, bootconf_filename,
                                               cancellable, error))
         return FALSE;
     }