treefile: Add option to label /usr/etc as /etc

Depends on ostreedev/ostree#3063

This is intended for use with ostreedev/ostree#2868
but is conceptually orthogonal to it; we probably want to try
switching to this by default actually.

docs/treefile.md

@@ -138,6 +138,10 @@ It supports the following parameters:
     to the UNIX epoch time to be used as the build timestamp. Currently only
     fully supports the `bdb` backend. Somewhat experimental.
 
+ * `label-usretc-as-etc`: boolean, optional: If enabled, this sets the SELinux label for
+    files in `/usr/etc` as if they were in `/etc`.  This is important to aid
+    in having a "transient" `/etc`.
+
  * `cliwrap`: boolean, optional.  Defaults to `false`.  If enabled,
     rpm-ostree will replace binaries such as `/usr/bin/rpm` with
     wrappers that intercept unsafe operations, or adjust functionality.

rpmostree-cxxrs.cxx

@@ -1748,6 +1748,7 @@ struct Treefile final : public ::rust::Opaque
   bool get_documentation () const noexcept;
   bool get_recommends () const noexcept;
   bool get_selinux () const noexcept;
+  bool get_label_usretc_as_etc () const noexcept;
   ::rust::String get_gpg_key () const noexcept;
   ::rust::String get_automatic_version_suffix () const noexcept;
   bool get_container () const noexcept;
@@ -2588,6 +2589,9 @@ extern "C"
 
   bool rpmostreecxx$cxxbridge1$Treefile$get_selinux (::rpmostreecxx::Treefile const &self) noexcept;
 
+  bool rpmostreecxx$cxxbridge1$Treefile$get_label_usretc_as_etc (
+      ::rpmostreecxx::Treefile const &self) noexcept;
+
   void rpmostreecxx$cxxbridge1$Treefile$get_gpg_key (::rpmostreecxx::Treefile const &self,
                                                      ::rust::String *return$) noexcept;
 
@@ -5133,6 +5137,12 @@ Treefile::get_selinux () const noexcept
   return rpmostreecxx$cxxbridge1$Treefile$get_selinux (*this);
 }
 
+bool
+Treefile::get_label_usretc_as_etc () const noexcept
+{
+  return rpmostreecxx$cxxbridge1$Treefile$get_label_usretc_as_etc (*this);
+}
+
 ::rust::String
 Treefile::get_gpg_key () const noexcept
 {

rpmostree-cxxrs.h

@@ -1530,6 +1530,7 @@ struct Treefile final : public ::rust::Opaque
   bool get_documentation () const noexcept;
   bool get_recommends () const noexcept;
   bool get_selinux () const noexcept;
+  bool get_label_usretc_as_etc () const noexcept;
   ::rust::String get_gpg_key () const noexcept;
   ::rust::String get_automatic_version_suffix () const noexcept;
   bool get_container () const noexcept;

rust/src/lib.rs

@@ -607,6 +607,7 @@ pub mod ffi {
         fn get_documentation(&self) -> bool;
         fn get_recommends(&self) -> bool;
         fn get_selinux(&self) -> bool;
+        fn get_label_usretc_as_etc(&self) -> bool;
         fn get_gpg_key(&self) -> String;
         fn get_automatic_version_suffix(&self) -> String;
         fn get_container(&self) -> bool;

rust/src/treefile.rs

@@ -416,6 +416,7 @@ fn treefile_merge(dest: &mut TreeComposeConfig, src: &mut TreeComposeConfig) {
         basearch,
         rojig,
         selinux,
+        label_usretc_as_etc,
         ima,
         gpg_key,
         include,
@@ -1332,6 +1333,10 @@ impl Treefile {
         self.parsed.base.selinux.unwrap_or(true)
     }
 
+    pub(crate) fn get_label_usretc_as_etc(&self) -> bool {
+        self.parsed.base.label_usretc_as_etc.unwrap_or(true)
+    }
+
     pub(crate) fn get_gpg_key(&self) -> String {
         self.parsed.base.gpg_key.clone().unwrap_or_default()
     }
@@ -2473,6 +2478,8 @@ pub(crate) struct BaseComposeConfigFields {
     #[serde(skip_serializing_if = "Option::is_none")]
     pub(crate) selinux: Option<bool>,
     #[serde(skip_serializing_if = "Option::is_none")]
+    pub(crate) label_usretc_as_etc: Option<bool>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub(crate) ima: Option<bool>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub(crate) gpg_key: Option<String>,

src/app/rpmostree-compose-builtin-tree.cxx

@@ -1135,7 +1135,6 @@ static gboolean
 impl_commit_tree (RpmOstreeTreeComposeContext *self, GCancellable *cancellable, GError **error)
 {
   auto gpgkey = (*self->treefile_rs)->get_gpg_key ();
-  auto selinux = (*self->treefile_rs)->get_selinux ();
 
   /* pick up any initramfs regeneration args to shove into the metadata */
   JsonNode *initramfs_args = json_object_get_member (self->treefile, "initramfs-args");
@@ -1211,8 +1210,19 @@ impl_commit_tree (RpmOstreeTreeComposeContext *self, GCancellable *cancellable,
   if (!gpgkey.empty ())
     gpgkey_c = gpgkey.c_str ();
   auto container = (*self->treefile_rs)->get_container ();
+  RpmOstreeSELinuxMode selinux_mode;
+  {
+    auto selinux = (*self->treefile_rs)->get_selinux ();
+    auto label_usretc_as_etc = (*self->treefile_rs)->get_label_usretc_as_etc ();
+    if (selinux && label_usretc_as_etc)
+      selinux_mode = RPMOSTREE_SELINUX_MODE_V1;
+    else if (selinux)
+      selinux_mode = RPMOSTREE_SELINUX_MODE_V0;
+    else
+      selinux_mode = RPMOSTREE_SELINUX_MODE_DISABLED;
+  }
   if (!rpmostree_compose_commit (self->rootfs_dfd, self->build_repo, parent_revision, metadata,
-                                 detached_metadata, gpgkey_c, container, selinux,
+                                 detached_metadata, gpgkey_c, container, selinux_mode,
                                  self->devino_cache, &new_revision, cancellable, error))
     return glnx_prefix_error (error, "Writing commit");
   g_assert (new_revision != NULL);

src/libpriv/rpmostree-postprocess.cxx

@@ -761,16 +761,19 @@ on_progress_timeout (gpointer datap)
 gboolean
 rpmostree_compose_commit (int rootfs_fd, OstreeRepo *repo, const char *parent_revision,
                           GVariant *src_metadata, GVariant *detached_metadata,
-                          const char *gpg_keyid, gboolean container, gboolean enable_selinux,
+                          const char *gpg_keyid, gboolean container, RpmOstreeSELinuxMode selinux,
                           OstreeRepoDevInoCache *devino_cache, char **out_new_revision,
                           GCancellable *cancellable, GError **error)
 {
+  int label_modifier_flags = 0;
   g_autoptr (OstreeSePolicy) sepolicy = NULL;
-  if (enable_selinux)
+  if (selinux != RPMOSTREE_SELINUX_MODE_DISABLED)
     {
       sepolicy = ostree_sepolicy_new_at (rootfs_fd, cancellable, error);
       if (!sepolicy)
         return FALSE;
+      if (selinux == RPMOSTREE_SELINUX_MODE_V1)
+        label_modifier_flags |= OSTREE_REPO_COMMIT_MODIFIER_FLAGS_USRETC_AS_ETC;
     }
 
   g_autoptr (OstreeMutableTree) mtree = ostree_mutable_tree_new ();
@@ -783,7 +786,7 @@ rpmostree_compose_commit (int rootfs_fd, OstreeRepo *repo, const char *parent_re
    */
   auto modifier_flags = static_cast<OstreeRepoCommitModifierFlags> (
       OSTREE_REPO_COMMIT_MODIFIER_FLAGS_ERROR_ON_UNLABELED
-      | OSTREE_REPO_COMMIT_MODIFIER_FLAGS_CONSUME);
+      | OSTREE_REPO_COMMIT_MODIFIER_FLAGS_CONSUME | label_modifier_flags);
   /* If changing this, also look at changing rpmostree-unpacker.c */
   g_autoptr (OstreeRepoCommitModifier) commit_modifier
       = ostree_repo_commit_modifier_new (modifier_flags, NULL, NULL, NULL);
@@ -794,7 +797,7 @@ rpmostree_compose_commit (int rootfs_fd, OstreeRepo *repo, const char *parent_re
 
   if (sepolicy && ostree_sepolicy_get_name (sepolicy) != NULL)
     ostree_repo_commit_modifier_set_sepolicy (commit_modifier, sepolicy);
-  else if (enable_selinux)
+  else if (selinux != RPMOSTREE_SELINUX_MODE_DISABLED)
     return glnx_throw (error, "SELinux enabled, but no policy found");
 
   if (devino_cache)

src/libpriv/rpmostree-postprocess.h

@@ -34,12 +34,19 @@ gboolean rpmostree_prepare_rootfs_get_sepolicy (int dfd, OstreeSePolicy **out_se
 gboolean rpmostree_rootfs_fixup_selinux_store_root (int rootfs_dfd, GCancellable *cancellable,
                                                     GError **error);
 
+typedef enum
+{
+  RPMOSTREE_SELINUX_MODE_DISABLED,
+  RPMOSTREE_SELINUX_MODE_V0, // Enabled
+  RPMOSTREE_SELINUX_MODE_V1, // Label /usr/etc as /etc
+} RpmOstreeSELinuxMode;
+
 gboolean rpmostree_compose_commit (int rootfs_dfd, OstreeRepo *repo, const char *parent,
                                    GVariant *metadata, GVariant *detached_metadata,
                                    const char *gpg_keyid, gboolean container,
-                                   gboolean enable_selinux, OstreeRepoDevInoCache *devino_cache,
-                                   char **out_new_revision, GCancellable *cancellable,
-                                   GError **error);
+                                   RpmOstreeSELinuxMode selinux,
+                                   OstreeRepoDevInoCache *devino_cache, char **out_new_revision,
+                                   GCancellable *cancellable, GError **error);
 
 G_END_DECLS