{
  "slug": "block-device-read-only",
  "term": "Linux block-device read-only flag",
  "aliases": [
    "Block-device read-only state"
  ],
  "definition": "The Linux block-device read-only flag is a software-controlled device state exposed through block-device ioctls to restrict write access.",
  "note": "The util-linux v2.41.1 manual warns that changing the flag may leave existing active access unaffected, including a filesystem already in read-write use. [blockdev] A flag value alone is not evidence of a validated forensic write-blocking workflow; NIST publishes software write-blocker test resources, so software and unvalidated are not synonyms. [write-block-testing]",
  "limitations": [
    {
      "text": "Device state, filesystem state and subvolume properties have distinct scopes.",
      "citationIds": [
        "blockdev",
        "mount-scope"
      ]
    }
  ],
  "related": [
    "read-only-mount",
    "btrfs-read-only-subvolume"
  ],
  "citations": [
    {
      "id": "blockdev",
      "title": "util-linux v2.41.1: blockdev(8), read-only flag and active-access caveat",
      "url": "https://kernel.googlesource.com/pub/scm/utils/util-linux/util-linux/+/refs/tags/v2.41.1/disk-utils/blockdev.8.adoc",
      "accessed": "2026-10-15"
    },
    {
      "id": "mount-scope",
      "title": "util-linux v2.41.1: mount(8), Read-only Setting Notes",
      "url": "https://kernel.googlesource.com/pub/scm/utils/util-linux/util-linux/+/refs/tags/v2.41.1/sys-utils/mount.8.adoc",
      "accessed": "2026-10-15"
    },
    {
      "id": "write-block-testing",
      "title": "NIST CFTT: Software Write Block testing resources",
      "url": "https://www.nist.gov/itl/csd/secure-systems-and-applications/computer-forensics-tool-testing-program-cftt/cftt-9",
      "accessed": "2026-10-15"
    },
    {
      "id": "hesela",
      "title": "Hesela: Btrfs tree logs and read-only scope boundaries",
      "url": "https://hesela.com/analyses/btrfs-tree-log-read-only-replay/#read-only-scopes",
      "accessed": "2026-10-15"
    }
  ],
  "status": "shipping",
  "advantages": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-15"
}