chore(code): split much of the efi support code to crates/eficore

crates/eficore/src/bootloader_interface.rs

@@ -0,0 +1,317 @@
+use crate::bootloader_interface::bitflags::LoaderFeatures;
+use crate::platform::timer::PlatformTimer;
+use crate::variables::{VariableClass, VariableController};
+use alloc::format;
+use alloc::string::{String, ToString};
+use alloc::vec::Vec;
+use anyhow::{Context, Result};
+use uefi::proto::device_path::DevicePath;
+use uefi::{Guid, guid};
+use uefi_raw::table::runtime::VariableVendor;
+
+/// bitflags: LoaderFeatures bitflags.
+mod bitflags;
+
+/// The name of the bootloader to tell the system.
+const LOADER_NAME: &str = "Sprout";
+
+/// Represents the configured timeout for the bootloader interface.
+pub enum BootloaderInterfaceTimeout {
+    /// Force the menu to be shown.
+    MenuForce,
+    /// Hide the menu.
+    MenuHidden,
+    /// Disable the menu.
+    MenuDisabled,
+    /// Set a timeout for the menu.
+    Timeout(u64),
+    /// Timeout is unspecified.
+    Unspecified,
+}
+
+/// Bootloader Interface support.
+pub struct BootloaderInterface;
+
+impl BootloaderInterface {
+    /// Bootloader Interface GUID from https://systemd.io/BOOT_LOADER_INTERFACE
+    const VENDOR: VariableController = VariableController::new(VariableVendor(guid!(
+        "4a67b082-0a4c-41cf-b6c7-440b29bb8c4f"
+    )));
+
+    /// The feature we support in Sprout.
+    fn features() -> LoaderFeatures {
+        LoaderFeatures::Xbootldr
+            | LoaderFeatures::LoadDriver
+            | LoaderFeatures::Tpm2ActivePcrBanks
+            | LoaderFeatures::RetainShim
+            | LoaderFeatures::ConfigTimeout
+            | LoaderFeatures::ConfigTimeoutOneShot
+            | LoaderFeatures::MenuDisable
+            | LoaderFeatures::EntryDefault
+            | LoaderFeatures::EntryOneShot
+    }
+
+    /// Tell the system that Sprout was initialized at the current time.
+    pub fn mark_init(timer: &PlatformTimer) -> Result<()> {
+        Self::mark_time("LoaderTimeInitUSec", timer)
+    }
+
+    /// Tell the system that Sprout is about to execute the boot entry.
+    pub fn mark_exec(timer: &PlatformTimer) -> Result<()> {
+        Self::mark_time("LoaderTimeExecUSec", timer)
+    }
+
+    /// Tell the system that Sprout is about to display the menu.
+    pub fn mark_menu(timer: &PlatformTimer) -> Result<()> {
+        Self::mark_time("LoaderTimeMenuUSec", timer)
+    }
+
+    /// Tell the system about the current time as measured by the platform timer.
+    /// Sets the variable specified by `key` to the number of microseconds.
+    fn mark_time(key: &str, timer: &PlatformTimer) -> Result<()> {
+        // Measure the elapsed time since the hardware timer was started.
+        let elapsed = timer.elapsed_since_lifetime();
+        Self::VENDOR.set_cstr16(
+            key,
+            &elapsed.as_micros().to_string(),
+            VariableClass::BootAndRuntimeTemporary,
+        )
+    }
+
+    /// Tell the system what loader is being used and our features.
+    pub fn set_loader_info() -> Result<()> {
+        // Set the LoaderInfo variable with the name of the loader.
+        Self::VENDOR
+            .set_cstr16(
+                "LoaderInfo",
+                LOADER_NAME,
+                VariableClass::BootAndRuntimeTemporary,
+            )
+            .context("unable to set loader info variable")?;
+
+        // Set the LoaderFeatures variable with the features we support.
+        Self::VENDOR
+            .set_u64le(
+                "LoaderFeatures",
+                Self::features().bits(),
+                VariableClass::BootAndRuntimeTemporary,
+            )
+            .context("unable to set loader features variable")?;
+        Ok(())
+    }
+
+    /// Tell the system the relative path to the partition root of the current bootloader.
+    pub fn set_loader_path(path: &DevicePath) -> Result<()> {
+        let subpath =
+            crate::path::device_path_subpath(path).context("unable to get loader path subpath")?;
+        Self::VENDOR.set_cstr16(
+            "LoaderImageIdentifier",
+            &subpath,
+            VariableClass::BootAndRuntimeTemporary,
+        )
+    }
+
+    /// Tell the system what the partition GUID of the ESP Sprout was booted from is.
+    pub fn set_partition_guid(guid: &Guid) -> Result<()> {
+        Self::VENDOR.set_cstr16(
+            "LoaderDevicePartUUID",
+            &guid.to_string(),
+            VariableClass::BootAndRuntimeTemporary,
+        )
+    }
+
+    /// Tell the system what boot entries are available.
+    pub fn set_entries<N: AsRef<str>>(entries: impl Iterator<Item = N>) -> Result<()> {
+        // Entries are stored as a null-terminated list of CString16 strings back to back.
+        // Iterate over the entries and convert them to CString16 placing them into data.
+        let mut data = Vec::new();
+        for entry in entries {
+            // Convert the entry to CString16 little endian.
+            let encoded = entry
+                .as_ref()
+                .encode_utf16()
+                .flat_map(|c| c.to_le_bytes())
+                .collect::<Vec<u8>>();
+            // Write the bytes into the data buffer.
+            data.extend_from_slice(&encoded);
+            // Add a null terminator to the end of the entry.
+            data.extend_from_slice(&[0, 0]);
+        }
+
+        // If no data was generated, we will do nothing.
+        if data.is_empty() {
+            return Ok(());
+        }
+
+        Self::VENDOR.set(
+            "LoaderEntries",
+            &data,
+            VariableClass::BootAndRuntimeTemporary,
+        )
+    }
+
+    /// Tell the system what the selected boot entry is.
+    pub fn set_selected_entry(entry: String) -> Result<()> {
+        Self::VENDOR.set_cstr16(
+            "LoaderEntrySelected",
+            &entry,
+            VariableClass::BootAndRuntimeTemporary,
+        )
+    }
+
+    /// Tell the system about the UEFI firmware we are running on.
+    pub fn set_firmware_info() -> Result<()> {
+        // Access the firmware revision.
+        let firmware_revision = uefi::system::firmware_revision();
+
+        // Access the UEFI revision.
+        let uefi_revision = uefi::system::uefi_revision();
+
+        // Format the firmware information string into something human-readable.
+        let firmware_info = format!(
+            "{} {}.{:02}",
+            uefi::system::firmware_vendor(),
+            firmware_revision >> 16,
+            firmware_revision & 0xffff,
+        );
+        Self::VENDOR.set_cstr16(
+            "LoaderFirmwareInfo",
+            &firmware_info,
+            VariableClass::BootAndRuntimeTemporary,
+        )?;
+
+        // Format the firmware revision into something human-readable.
+        let firmware_type = format!(
+            "UEFI {}.{:02}",
+            uefi_revision.major(),
+            uefi_revision.minor()
+        );
+        Self::VENDOR.set_cstr16(
+            "LoaderFirmwareType",
+            &firmware_type,
+            VariableClass::BootAndRuntimeTemporary,
+        )
+    }
+
+    /// Tell the system what the number of active PCR banks is.
+    /// If this is zero, that is okay.
+    pub fn set_tpm2_active_pcr_banks(value: u32) -> Result<()> {
+        // Format the value into the specification format.
+        let value = format!("0x{:08x}", value);
+        Self::VENDOR.set_cstr16(
+            "LoaderTpm2ActivePcrBanks",
+            &value,
+            VariableClass::BootAndRuntimeTemporary,
+        )
+    }
+
+    /// Retrieve the timeout value from the bootloader interface, using the specified `key`.
+    /// `remove` indicates whether, when found, we remove the variable.
+    fn get_timeout_value(key: &str, remove: bool) -> Result<Option<BootloaderInterfaceTimeout>> {
+        // Retrieve the timeout value from the bootloader interface.
+        let Some(value) = Self::VENDOR
+            .get_cstr16(key)
+            .context("unable to get timeout value")?
+        else {
+            return Ok(None);
+        };
+
+        // If we reach here, we know the value was specified.
+        // If `remove` is true, remove the variable.
+        if remove {
+            Self::VENDOR
+                .remove(key)
+                .context("unable to remove timeout variable")?;
+        }
+
+        // If the value is empty, return Unspecified.
+        if value.is_empty() {
+            return Ok(Some(BootloaderInterfaceTimeout::Unspecified));
+        }
+
+        // If the value is "menu-force", return MenuForce.
+        if value == "menu-force" {
+            return Ok(Some(BootloaderInterfaceTimeout::MenuForce));
+        }
+
+        // If the value is "menu-hidden", return MenuHidden.
+        if value == "menu-hidden" {
+            return Ok(Some(BootloaderInterfaceTimeout::MenuHidden));
+        }
+
+        // If the value is "menu-disabled", return MenuDisabled.
+        if value == "menu-disabled" {
+            return Ok(Some(BootloaderInterfaceTimeout::MenuDisabled));
+        }
+
+        // Parse the value as a u64 to decode an numeric value.
+        let value = value
+            .parse::<u64>()
+            .context("unable to parse timeout value")?;
+
+        // The specification says that a value of 0 means that the menu should be hidden.
+        if value == 0 {
+            return Ok(Some(BootloaderInterfaceTimeout::MenuHidden));
+        }
+
+        // If we reach here, we know it must be a real timeout value.
+        Ok(Some(BootloaderInterfaceTimeout::Timeout(value)))
+    }
+
+    /// Get the timeout from the bootloader interface.
+    /// This indicates how the menu should behave.
+    /// If no values are set, Unspecified is returned.
+    pub fn get_timeout() -> Result<BootloaderInterfaceTimeout> {
+        // Attempt to acquire the value of the LoaderConfigTimeoutOneShot variable.
+        // This should take precedence over the LoaderConfigTimeout variable.
+        let oneshot = Self::get_timeout_value("LoaderConfigTimeoutOneShot", true)
+            .context("unable to check for LoaderConfigTimeoutOneShot variable")?;
+
+        // If oneshot was found, return it.
+        if let Some(oneshot) = oneshot {
+            return Ok(oneshot);
+        }
+
+        // Attempt to acquire the value of the LoaderConfigTimeout variable.
+        // This will be used if the LoaderConfigTimeoutOneShot variable is not set.
+        let direct = Self::get_timeout_value("LoaderConfigTimeout", false)
+            .context("unable to check for LoaderConfigTimeout variable")?;
+
+        // If direct was found, return it.
+        if let Some(direct) = direct {
+            return Ok(direct);
+        }
+
+        // If we reach here, we know that neither variable was set.
+        // We provide the unspecified value instead.
+        Ok(BootloaderInterfaceTimeout::Unspecified)
+    }
+
+    /// Get the default entry set by the bootloader interface.
+    pub fn get_default_entry() -> Result<Option<String>> {
+        Self::VENDOR
+            .get_cstr16("LoaderEntryDefault")
+            .context("unable to get default entry from bootloader interface")
+    }
+
+    /// Get the oneshot entry set by the bootloader interface.
+    /// This should be the entry we boot.
+    pub fn get_oneshot_entry() -> Result<Option<String>> {
+        // Acquire the value of the LoaderEntryOneShot variable.
+        // If it is not set, return None.
+        let Some(value) = Self::VENDOR
+            .get_cstr16("LoaderEntryOneShot")
+            .context("unable to get oneshot entry from bootloader interface")?
+        else {
+            return Ok(None);
+        };
+
+        // Remove the oneshot entry from the bootloader interface.
+        Self::VENDOR
+            .remove("LoaderEntryOneShot")
+            .context("unable to remove oneshot entry")?;
+
+        // Return the oneshot value.
+        Ok(Some(value))
+    }
+}