ELF Package and Dlopen Notes Reference Implementation

Description

This repository provides RPM and DEB packaging tools to generate an .note.package ELF note that will be linked into compiled binaries (programs and shared libraries) to provide metadata about the package for which the binary was compiled.

See Package Metadata for Core Files for the overview and details.

When building binaries, the --package-metadata option provided by bfd, gold, mold, and lld shall be used to inject the metadata into the binary.

Displaying package notes

Raw:

$ objdump -j .note.package -s /usr/bin/ls

/usr/bin/ls:     file format elf64-x86-64

Contents of section .note.package:
 03cc 04000000 7c000000 7e1afeca 46444f00  ....|...~...FDO.
 03dc 7b227479 7065223a 2272706d 222c226e  {"type":"rpm","n
 03ec 616d6522 3a22636f 72657574 696c7322  ame":"coreutils"
 03fc 2c227665 7273696f 6e223a22 392e342d  ,"version":"9.4-
 040c 372e6663 3430222c 22617263 68697465  7.fc40","archite
 041c 63747572 65223a22 7838365f 3634222c  cture":"x86_64",
 042c 226f7343 7065223a 22637065 3a2f6f3a  "osCpe":"cpe:/o:
 043c 6665646f 72617072 6f6a6563 743a6665  fedoraproject:fe
 044c 646f7261 3a343022 7d000000           dora:40"}...

Pretty:

$ systemd-analyze inspect-elf /usr/bin/ls
           path: /usr/bin/ls
        elfType: executable
elfArchitecture: AMD x86-64

           type: rpm
           name: coreutils
        version: 9.4-7.fc40
   architecture: x86_64
          osCpe: cpe:/o:fedoraproject:fedora:40
        buildId: 40e5a1570a9d97fc48f5c61cfb7690fec0f872b2

dlopen() metadata

This package also provides scripts to extract and display .note.dlopen ELF notes that are used to describe libraries loaded via dlopen(3).

See dlopen() Metadata for ELF Files for the overview and details.

Displaying dlopen() notes

Raw:

$ objdump -j .note.dlopen -s /usr/lib64/systemd/libsystemd-shared-257.so

/usr/lib64/systemd/libsystemd-shared-257.so:     file format elf64-x86-64

Contents of section .note.dlopen:
 0334 04000000 8e000000 0a0c7c40 46444f00  ..........|@FDO.
 0344 5b7b2266 65617475 7265223a 22627066  [{"feature":"bpf
 0354 222c2264 65736372 69707469 6f6e223a  ","description":
 0364 22537570 706f7274 20666972 6577616c  "Support firewal
 0374 6c696e67 20616e64 2073616e 64626f78  ling and sandbox
 0384 696e6720 77697468 20425046 222c2270  ing with BPF","p
 0394 72696f72 69747922 3a227375 67676573  riority":"sugges
 03a4 74656422 2c22736f 6e616d65 223a5b22  ted","soname":["
 03b4 6c696262 70662e73 6f2e3122 2c226c69  libbpf.so.1","li
 03c4 62627066 2e736f2e 30225d7d 5d000000  bbpf.so.0"]}]...
 03d4 04000000 9e000000 0a0c7c40 46444f00  ..........|@FDO.
...

Pretty:

$ dlopen-notes /usr/lib64/systemd/libsystemd-shared-257.so
# /usr/lib64/systemd/libsystemd-shared-257.so
[
  {
    "feature": "bpf",
    "description": "Support firewalling and sandboxing with BPF",
    "priority": "suggested",
    "soname": [
      "libbpf.so.1",
      "libbpf.so.0"
    ]
  },
...

Requirements

• binutils (>= 2.39)
• mold (>= 1.3.0)
• lld (>= 15.0.0)
• python (>= 3.8)