[PATCH v2] libebl: recognize FDO Packaging Metadata ELF note

[luca.boccassi@gmail.com]

From: Luca Boccassi <bluca@debian.org>

As defined on: https://systemd.io/COREDUMP_PACKAGE_METADATA/
this note will be used starting from Fedora 36. Allow
readelf --notes to pretty print it:

Note section [ 3] '.note.package' of 76 bytes at offset 0x2e8:
  Owner          Data size  Type
  FDO                   57  FDO_PACKAGING_METADATA
    Packaging Metadata: {"type":"deb","name":"fsverity-utils","version":"1.3-1"}

Signed-off-by: Luca Boccassi <luca.boccassi@microsoft.com>
---
v2: check that note payload is NULL terminated

 libebl/eblobjnote.c         | 3 +++
 libebl/eblobjnotetypename.c | 3 +++
 libelf/elf.h                | 3 +++
 3 files changed, 9 insertions(+)

diff --git a/libebl/eblobjnote.c b/libebl/eblobjnote.c
index 36efe275..e3ad1409 100644
--- a/libebl/eblobjnote.c
+++ b/libebl/eblobjnote.c
@@ -288,6 +288,9 @@ ebl_object_note (Ebl *ebl, uint32_t namesz, const char *name, uint32_t type,
       if (descsz == 0 && type == NT_VERSION)
 	return;
 
+      if (strcmp ("FDO", name) == 0 && type == FDO_PACKAGING_METADATA && descsz > 0 && desc[descsz - 1] == '\0')
+	printf("    Packaging Metadata: %.*s\n", (int) descsz, desc);
+
       /* Everything else should have the "GNU" owner name.  */
       if (strcmp ("GNU", name) != 0)
 	return;
diff --git a/libebl/eblobjnotetypename.c b/libebl/eblobjnotetypename.c
index 4662906d..863f20e4 100644
--- a/libebl/eblobjnotetypename.c
+++ b/libebl/eblobjnotetypename.c
@@ -101,6 +101,9 @@ ebl_object_note_type_name (Ebl *ebl, const char *name, uint32_t type,
 	  return buf;
 	}
 
+      if (strcmp (name, "FDO") == 0 && type == FDO_PACKAGING_METADATA)
+	return "FDO_PACKAGING_METADATA";
+
       if (strcmp (name, "GNU") != 0)
 	{
 	  /* NT_VERSION is special, all data is in the name.  */
diff --git a/libelf/elf.h b/libelf/elf.h
index 8e3e618f..633f9f67 100644
--- a/libelf/elf.h
+++ b/libelf/elf.h
@@ -1297,6 +1297,9 @@ typedef struct
 /* Program property.  */
 #define NT_GNU_PROPERTY_TYPE_0 5
 
+/* Packaging metadata as defined on https://systemd.io/COREDUMP_PACKAGE_METADATA/ */
+#define FDO_PACKAGING_METADATA 0xcafe1a7e
+
 /* Note section name of program property.   */
 #define NOTE_GNU_PROPERTY_SECTION_NAME ".note.gnu.property"
 
-- 
2.33.0