Establishing Trust in Linux Keyrings - Is Trust Built-in, Imputed, or Transitive?
summary
Linux 5.18 adds a .machine keyring that links to the secondary trusted keyring and can verify kernels, modules and kexec images using keys imported via UEFI variables or admin tools, solving long‑carried distro patches but widening attack surface because those keys inherit full verification powers and disable IMA’s more restricted checks. Proposal narrows the machine keyring to CA-only certs so it vouches for signing chains while leaving code/data keys to IMA, restoring separation of duties and enabling safer runtime rotation. introduced in 5.18
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chapters (4)
- 0:00Start
- 1:22Goals of this talk
- 16:48Advantages and disadvantages of the machine keyring
- 25:38Advantages and disadvantages of parent-only certificates in.machine
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