uki: introduce support for a .efifwauto section

UKIs can be used to bundle firmware blobs that can be measured and
used on a confidential computing environment. There can be more than one
firmware blob bundle, each one for a specific platform. Also firmware images
can themselves be containers like IGVM files that can in turn bundle the
actual firmware blob.

Add support to introduce a .efifwauto section in UKI that can be used for
firmware blobs/images. There can be multiple such sections and each section
can contain a single firmware image.

The matching .hwids entry for a specific platform can be used to select the
most appropriate firmware blob. Subsequent patches will add full support
for this selection mechanism.

ukify tool has been also changed to support addition of a firmware image
in UKI. For example:

ukify.py build \
        --stub ./build/src/boot/efi/linuxx64.efi.stub \
        --linux bzImage \
        --cmdline='blah blah debug' \
        --firmware ~/OVMF.fd \
        --output=root/efi/boot/bootx64.efi

Co-authored-by: harald.hoyer@gmail.com

man/systemd-stub.xml

@@ -91,6 +91,15 @@
       the same matching procedure. If a match is found, that <literal>.dtbauto</literal> section will be
       loaded and will override <varname>.dtb</varname> if present.</para></listitem>
 
+      <listitem><para>Zero or more <literal>.efifwauto</literal> sections for the firmware image. It works
+      in many ways similar to <varname>.dtbauto</varname> sections. <filename>systemd-stub</filename>
+      will always use the first matching one. The match is performed by first selecting the most appropriate
+      entry in the <varname>.hwids</varname> section based on the hardware IDs supplied by SMBIOS (see below).
+      If a suitable entry is found, the <varname>compatible</varname> string from that entry will be used to
+      perform the matching procedure for firmware blobs in <varname>.efifwauto</varname> section. The first
+      matching firmware will be loaded.
+      </para></listitem>
+
       <listitem><para>Zero or more <literal>.hwids</literal> sections with hardware IDs of the machines to
       match DeviceTrees. <filename>systemd-stub</filename> will use the SMBIOS data to calculate hardware IDs
       of the machine (as per <ulink

src/fundamental/uki.c

@@ -23,5 +23,6 @@ const char* const unified_sections[_UNIFIED_SECTION_MAX + 1] = {
         [UNIFIED_SECTION_PROFILE]    = ".profile",
         [UNIFIED_SECTION_DTBAUTO]    = ".dtbauto",
         [UNIFIED_SECTION_HWIDS]      = ".hwids",
+        [UNIFIED_SECTION_FIRMWARE]   = ".efifwauto",
         NULL,
 };

src/fundamental/uki.h

@@ -20,6 +20,7 @@ typedef enum UnifiedSection {
         UNIFIED_SECTION_PROFILE,
         UNIFIED_SECTION_DTBAUTO,
         UNIFIED_SECTION_HWIDS,
+        UNIFIED_SECTION_FIRMWARE,
         _UNIFIED_SECTION_MAX,
 } UnifiedSection;
 

src/measure/measure.c

@@ -104,6 +104,7 @@ static int help(int argc, char *argv[], void *userdata) {
                "     --linux=PATH        Path to Linux kernel image file        %7$s .linux\n"
                "     --osrel=PATH        Path to os-release file                %7$s .osrel\n"
                "     --cmdline=PATH      Path to file with kernel command line  %7$s .cmdline\n"
+               "     --firmware=PATH     Path to firmware image file            %7$s .efifwauto\n"
                "     --initrd=PATH       Path to initrd image file              %7$s .initrd\n"
                "     --ucode=PATH        Path to microcode image file           %7$s .ucode\n"
                "     --splash=PATH       Path to splash bitmap file             %7$s .splash\n"
@@ -158,8 +159,9 @@ static int parse_argv(int argc, char *argv[]) {
                 ARG_PCRPKEY,
                 ARG_PROFILE,
                 ARG_HWIDS,
+                ARG_DTBAUTO,
                 _ARG_SECTION_LAST,
-                ARG_DTBAUTO = _ARG_SECTION_LAST,
+                ARG_FIRMWARE = _ARG_SECTION_LAST,
                 ARG_BANK,
                 ARG_PRIVATE_KEY,
                 ARG_PRIVATE_KEY_SOURCE,
@@ -180,6 +182,7 @@ static int parse_argv(int argc, char *argv[]) {
                 { "osrel",              required_argument, NULL, ARG_OSREL              },
                 { "cmdline",            required_argument, NULL, ARG_CMDLINE            },
                 { "initrd",             required_argument, NULL, ARG_INITRD             },
+                { "firmware",           required_argument, NULL, ARG_FIRMWARE           },
                 { "ucode",              required_argument, NULL, ARG_UCODE              },
                 { "splash",             required_argument, NULL, ARG_SPLASH             },
                 { "dtb",                required_argument, NULL, ARG_DTB                },

src/ukify/ukify.py

@@ -242,6 +242,7 @@ class UkifyConfig:
     efi_arch: str
     hwids: Path
     initrd: list[Path]
+    firmware: list[Path]
     join_profiles: list[Path]
     json: Union[Literal['pretty'], Literal['short'], Literal['off']]
     linux: Optional[Path]
@@ -369,6 +370,7 @@ DEFAULT_SECTIONS_TO_SHOW = {
     '.dtb':       'binary',
     '.dtbauto':   'binary',
     '.hwids':     'binary',
+    '.efifwauto': 'binary',
     '.cmdline':   'text',
     '.osrel':     'text',
     '.uname':     'text',
@@ -1213,6 +1215,7 @@ def make_uki(opts: UkifyConfig) -> None:
         ('.splash',     opts.splash,     True),
         ('.pcrpkey',    pcrpkey,         True),
         ('.initrd',     initrd,          True),
+        *(('.efifwauto', fw, True) for fw in opts.firmware),
         ('.ucode',      opts.microcode,  True),
     ]  # fmt: skip
 
@@ -1269,6 +1272,7 @@ def make_uki(opts: UkifyConfig) -> None:
         '.osrel',
         '.cmdline',
         '.initrd',
+        '.efifwauto',
         '.ucode',
         '.splash',
         '.dtb',
@@ -1729,6 +1733,16 @@ CONFIG_ITEMS = [
         config_key='UKI/Initrd',
         config_push=ConfigItem.config_list_prepend,
     ),
+    ConfigItem(
+        '--firmware',
+        metavar='PATH',
+        type=Path,
+        action='append',
+        default=[],
+        help='firmware file [.efifwauto section]',
+        config_key='UKI/Firmware',
+        config_push=ConfigItem.config_list_prepend,
+    ),
     ConfigItem(
         '--microcode',
         metavar='UCODE',