install: Add block to config, disable tpm2-luks unless opted-in

docs/src/bootc-install.md

@@ -113,14 +113,7 @@ taking precedence.  If for example you are building a derived container image fr
 you could create a `50-myos.toml`  that sets `type = "btrfs"` which will override the
 prior setting.
 
-Other available options, also under the `[install]` section:
-
-`kargs`: This allows setting kernel arguments which apply only at the time of `bootc install`.
-This option is particularly useful when creating derived/layered images; for example, a cloud
-image may want to have its default `console=` set, in contrast with a default base image.
-The values in this field are space separated.
-
-`root-fs-type`: This value is the same as `install.filesystem.root.type`.
+For other available options, see [bootc-install-config](man/bootc-install-config.md).
 
 ## Installing an "unconfigured" image
 

docs/src/man-md/bootc-install-config.md

@@ -20,6 +20,9 @@ This is the only defined toplevel table.
 
 The `install`` section supports two subfields:
 
+- `block`: An array of supported `to-disk` backends enabled by this base container image;
+   if not specified, this will just be `direct`.  The only other supported value is `tpm2-luks`.
+   The first value specified will be the default.  To enable both, use `block = ["direct", "tpm2-luks"]`.
 - `filesystem`: See below.
 - `kargs`: An array of strings; this will be appended to the set of kernel arguments.
 

lib/src/install/baseline.rs

@@ -79,9 +79,8 @@ pub(crate) struct InstallBlockDeviceOpts {
     ///
     /// direct: Filesystem written directly to block device
     /// tpm2-luks: Bind unlock of filesystem to presence of the default tpm2 device.
-    #[clap(long, value_enum, default_value_t)]
-    #[serde(default)]
-    pub(crate) block_setup: BlockSetup,
+    #[clap(long, value_enum)]
+    pub(crate) block_setup: Option<BlockSetup>,
 
     /// Target root filesystem type.
     #[clap(long, value_enum)]
@@ -297,7 +296,10 @@ pub(crate) fn install_create_rootfs(
     };
 
     let base_rootdev = findpart(ROOTPN)?;
-    let (rootdev, root_blockdev_kargs) = match opts.block_setup {
+    let block_setup = state
+        .install_config
+        .get_block_setup(opts.block_setup.as_ref().copied())?;
+    let (rootdev, root_blockdev_kargs) = match block_setup {
         BlockSetup::Direct => (base_rootdev, None),
         BlockSetup::Tpm2Luks => {
             let uuid = uuid::Uuid::new_v4().to_string();
@@ -394,7 +396,7 @@ pub(crate) fn install_create_rootfs(
         mount::mount(espdev, &efifs_path)?;
     }
 
-    let luks_device = match opts.block_setup {
+    let luks_device = match block_setup {
         BlockSetup::Direct => None,
         BlockSetup::Tpm2Luks => Some(luks_name.to_string()),
     };

lib/src/install/config.rs

@@ -6,6 +6,8 @@ use anyhow::{Context, Result};
 use fn_error_context::context;
 use serde::{Deserialize, Serialize};
 
+use super::baseline::BlockSetup;
+
 /// The toplevel config entry for installation configs stored
 /// in bootc/install (e.g. /etc/bootc/install/05-custom.toml)
 #[derive(Debug, Clone, Serialize, Deserialize, Default)]
@@ -39,6 +41,8 @@ pub(crate) struct BasicFilesystems {
 pub(crate) struct InstallConfiguration {
     /// Root filesystem type
     pub(crate) root_fs_type: Option<super::baseline::Filesystem>,
+    /// Enabled block storage configurations
+    pub(crate) block: Option<Vec<BlockSetup>>,
     pub(crate) filesystem: Option<BasicFilesystems>,
     /// Kernel arguments, applied at installation time
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -93,6 +97,7 @@ impl Mergeable for InstallConfiguration {
     /// Apply any values in other, overriding any existing values in `self`.
     fn merge(&mut self, other: Self) {
         merge_basic(&mut self.root_fs_type, other.root_fs_type);
+        merge_basic(&mut self.block, other.block);
         self.filesystem.merge(other.filesystem);
         if let Some(other_kargs) = other.kargs {
             self.kargs
@@ -103,8 +108,8 @@ impl Mergeable for InstallConfiguration {
 }
 
 impl InstallConfiguration {
-    /// Some fields can be specified multiple ways.  This synchronizes the values of the fields
-    /// to ensure they're the same.
+    /// Set defaults (e.g. `block`), and also handle fields that can be specified multiple ways
+    /// by synchronizing the values of the fields to ensure they're the same.
     ///
     /// - install.root-fs-type is synchronized with install.filesystems.root.type; if
     ///   both are set, then the latter takes precedence
@@ -117,6 +122,10 @@ impl InstallConfiguration {
             let root = fs.root.get_or_insert_with(Default::default);
             root.fstype = Some(*rootfs);
         }
+
+        if self.block.is_none() {
+            self.block = Some(vec![BlockSetup::Direct]);
+        }
     }
 
     /// Convenience helper to access the root filesystem
@@ -128,6 +137,18 @@ impl InstallConfiguration {
     pub(crate) fn filter_to_external(&mut self) {
         self.kargs.take();
     }
+
+    pub(crate) fn get_block_setup(&self, default: Option<BlockSetup>) -> Result<BlockSetup> {
+        let valid_block_setups = self.block.as_deref().unwrap_or_default();
+        let default_block = valid_block_setups.iter().next().ok_or_else(|| {
+            anyhow::anyhow!("Empty block storage configuration in install configuration")
+        })?;
+        let block_setup = default.as_ref().unwrap_or(default_block);
+        if !valid_block_setups.contains(block_setup) {
+            anyhow::bail!("Block setup {block_setup:?} is not enabled in installation config");
+        }
+        Ok(*block_setup)
+    }
 }
 
 #[context("Loading configuration")]
@@ -177,8 +198,7 @@ root-fs-type = "xfs"
     let other = InstallConfigurationToplevel {
         install: Some(InstallConfiguration {
             root_fs_type: Some(Filesystem::Ext4),
-            filesystem: None,
-            kargs: None,
+            ..Default::default()
         }),
     };
     install.merge(other.install.unwrap());
@@ -206,14 +226,13 @@ kargs = ["console=ttyS0", "foo=bar"]
     assert_eq!(install.root_fs_type.unwrap(), Filesystem::Ext4);
     let other = InstallConfigurationToplevel {
         install: Some(InstallConfiguration {
-            root_fs_type: None,
-            filesystem: None,
             kargs: Some(
                 ["console=tty0", "nosmt"]
                     .into_iter()
                     .map(ToOwned::to_owned)
                     .collect(),
             ),
+            ..Default::default()
         }),
     };
     install.merge(other.install.unwrap());
@@ -245,13 +264,12 @@ type = "xfs"
     );
     let other = InstallConfigurationToplevel {
         install: Some(InstallConfiguration {
-            root_fs_type: None,
             filesystem: Some(BasicFilesystems {
                 root: Some(RootFS {
                     fstype: Some(Filesystem::Ext4),
                 }),
             }),
-            kargs: None,
+            ..Default::default()
         }),
     };
     install.merge(other.install.unwrap());
@@ -260,3 +278,43 @@ type = "xfs"
         Filesystem::Ext4
     );
 }
+
+#[test]
+fn test_parse_block() {
+    let c: InstallConfigurationToplevel = toml::from_str(
+        r##"[install.filesystem.root]
+type = "xfs"
+"##,
+    )
+    .unwrap();
+    let mut install = c.install.unwrap();
+    // Verify the default (but note canonicalization mutates)
+    {
+        let mut install = install.clone();
+        install.canonicalize();
+        assert_eq!(install.get_block_setup(None).unwrap(), BlockSetup::Direct);
+    }
+    let other = InstallConfigurationToplevel {
+        install: Some(InstallConfiguration {
+            block: Some(vec![]),
+            ..Default::default()
+        }),
+    };
+    install.merge(other.install.unwrap());
+    // Should be set, but zero length
+    assert_eq!(install.block.as_ref().unwrap().len(), 0);
+    assert!(install.get_block_setup(None).is_err());
+
+    let c: InstallConfigurationToplevel = toml::from_str(
+        r##"[install]
+block = ["tpm2-luks"]"##,
+    )
+    .unwrap();
+    let mut install = c.install.unwrap();
+    install.canonicalize();
+    assert_eq!(install.block.as_ref().unwrap().len(), 1);
+    assert_eq!(install.get_block_setup(None).unwrap(), BlockSetup::Tpm2Luks);
+
+    // And verify passing a disallowed config is an error
+    assert!(install.get_block_setup(Some(BlockSetup::Direct)).is_err());
+}