Module: Homebrew::Vulns::OsvExport Private

Defined in:
vulns/osv_export.rb

Overview

This module is part of a private API. This module may only be used in the Homebrew/brew repository. Third parties should avoid using this module if possible, as it may be removed or changed without warning.

Emits OSV-schema records for the Homebrew ecosystem describing CVEs that homebrew-core formulae resolve via shipped patches.

One record is written per (formula, vulnerability id) pair found in serialized_patches[].resolves. The record states that the formula was affected up to (but not including) the currently shipped version+revision; this is a "fixed at or before what we ship today" approximation, since the precise fix boundary requires homebrew-core git archaeology.

Record shape follows the OSV 1.7 schema and mirrors the Debian DSA layout (upstream listing the source CVE, affected[].ranges of type ECOSYSTEM, ecosystem_specific carrying the resolving patch detail).

See DevCmd::GenerateVulnsAdvisories for the entry point and https://github.com/Homebrew/advisory-database for the published feed.

Constant Summary collapse

SCHEMA_VERSION =

This constant is part of a private API. This constant may only be used in the Homebrew/brew repository. Third parties should avoid using this constant if possible, as it may be removed or changed without warning.

https://ossf.github.io/osv-schema/ — value of the emitted schema_version field, pinning the OSV schema release these records target. Homebrew and BREW were registered in that schema in ossf/osv-schema#576.

"1.7.3"
ECOSYSTEM =

This constant is part of a private API. This constant may only be used in the Homebrew/brew repository. Third parties should avoid using this constant if possible, as it may be removed or changed without warning. 

"Homebrew"
ID_PREFIX =

This constant is part of a private API. This constant may only be used in the Homebrew/brew repository. Third parties should avoid using this constant if possible, as it may be removed or changed without warning. 

"BREW"
PatchRef =

This constant is part of a private API. This constant may only be used in the Homebrew/brew repository. Third parties should avoid using this constant if possible, as it may be removed or changed without warning. 

T.type_alias { T::Hash[Symbol, T.any(String, T::Array[String])] }

Class Method Summary collapse

Class Method Details

.affected_entry(formula, vuln_id, patches, fixed) ⇒ Hash{Symbol => T.untyped}

This method is part of a private API. This method may only be used in the Homebrew/brew repository. Third parties should avoid using this method if possible, as it may be removed or changed without warning.

Parameters:

Returns:



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# File 'vulns/osv_export.rb', line 157

def self.affected_entry(formula, vuln_id, patches, fixed)
  {
    package:            {
      ecosystem: ECOSYSTEM,
      name:      formula.name,
      purl:      purl(formula.name),
    },
    ranges:             [
      {
        type:   "ECOSYSTEM",
        events: [{ introduced: "0" }, { fixed: }],
      },
    ],
    ecosystem_specific: {
      fix:     "patch",
      patches: patches_resolving(patches, vuln_id).filter_map { |p| patch_ref(p) },
    },
  }
end

.fetch_upstream(vuln_id) ⇒ Hash{String => T.untyped}, Symbol

This method is part of a private API. This method may only be used in the Homebrew/brew repository. Third parties should avoid using this method if possible, as it may be removed or changed without warning.

Returns :failed (not nil) on error so callers can distinguish a transient outage from a successful fetch that returned no enrichment.

Parameters:

Returns:



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# File 'vulns/osv_export.rb', line 215

def self.fetch_upstream(vuln_id)
  OSV.vulnerability(vuln_id)
rescue OSV::Error
  :failed
end

.merge_existing(path, record) ⇒ Hash{Symbol => T.untyped}?

This method is part of a private API. This method may only be used in the Homebrew/brew repository. Third parties should avoid using this method if possible, as it may be removed or changed without warning.

If a record already exists at path, carry forward its published timestamp and affected[].ranges (so the fixed boundary reflects when the annotation was first observed rather than drifting to today's pkg_version), and skip the write entirely when nothing else has changed. Records for annotations no longer in core are simply not visited, so they persist.

Parameters:

Returns:



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# File 'vulns/osv_export.rb', line 91

def self.merge_existing(path, record)
  return record unless File.file?(path)

  existing = JSON.parse(File.read(path))
  # Records written before `published` was introduced only have
  # `modified`; use it as the migration value so `published` does not
  # jump forward to today on first rewrite.
  if (existing_published = existing["published"] || existing["modified"])
    record[:published] = existing_published
  end
  Array(record[:affected]).each_with_index do |affected, index|
    existing_ranges = existing.dig("affected", index, "ranges")
    affected[:ranges] = existing_ranges if existing_ranges
  end

  # Compare as parsed structures so key ordering (which JSON does not
  # define but Ruby serialisation preserves) does not cause spurious
  # rewrites of a hand-formatted or differently-serialised existing file.
  return if JSON.parse(JSON.generate(record)).except("modified") == existing.except("modified")

  record
rescue JSON::ParserError
  record
end

.patch_ref(patch) ⇒ PatchRef?

This method is part of a private API. This method may only be used in the Homebrew/brew repository. Third parties should avoid using this method if possible, as it may be removed or changed without warning.

Parameters:

Returns:



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# File 'vulns/osv_export.rb', line 203

def self.patch_ref(patch)
  ref = T.let({}, PatchRef)
  ref[:type] = patch["type"] if patch["type"]
  ref[:url] = patch["url"] if patch["url"]
  ref[:file] = patch["file"] if patch["file"]
  ref[:apply] = patch["apply"] if patch["apply"]
  ref.presence
end

.patches_resolving(serialized_patches, vuln_id) ⇒ Array<Hash{String => T.untyped}>

This method is part of a private API. This method may only be used in the Homebrew/brew repository. Third parties should avoid using this method if possible, as it may be removed or changed without warning.

Parameters:

Returns:



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# File 'vulns/osv_export.rb', line 193

def self.patches_resolving(serialized_patches, vuln_id)
  target = vuln_id.upcase
  serialized_patches.select do |p|
    Array(p["resolves"]).any? { |r| r.is_a?(Hash) && r["type"] == "security" && r["id"].to_s.upcase == target }
  end
end

.purl(name) ⇒ String

This method is part of a private API. This method may only be used in the Homebrew/brew repository. Third parties should avoid using this method if possible, as it may be removed or changed without warning.

Parameters:

Returns:



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# File 'vulns/osv_export.rb', line 185

def self.purl(name)
  "pkg:brew/#{name.gsub(/[@+]/, PURL_NAME_ENCODE)}"
end

.record_for(formula, vuln_id, patches: formula.serialized_patches, fixed: formula.pkg_version.to_s, upstream: nil, now: Time.now.utc) ⇒ Hash{Symbol => T.untyped}

This method is part of a private API. This method may only be used in the Homebrew/brew repository. Third parties should avoid using this method if possible, as it may be removed or changed without warning.

Parameters:

  • formula (Formula)
  • vuln_id (String)
  • patches (Array<Hash{String => T.untyped}>) (defaults to: formula.serialized_patches)
  • fixed (String) (defaults to: formula.pkg_version.to_s)
  • upstream (Hash{String => T.untyped}, nil) (defaults to: nil)
  • now (Time) (defaults to: Time.now.utc)

Returns:



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# File 'vulns/osv_export.rb', line 121

def self.record_for(formula, vuln_id, patches: formula.serialized_patches,
                    fixed: formula.pkg_version.to_s, upstream: nil, now: Time.now.utc)
  timestamp = now.strftime("%Y-%m-%dT%H:%M:%SZ")
  record = T.let({
    schema_version:    SCHEMA_VERSION,
    id:                "#{ID_PREFIX}-#{formula.name}-#{vuln_id}",
    published:         timestamp,
    modified:          timestamp,
    upstream:          [vuln_id],
    affected:          [affected_entry(formula, vuln_id, patches, fixed)],
    database_specific: { source: "generated" },
  }, T::Hash[Symbol, T.untyped])

  if upstream
    record[:summary] = upstream["summary"] if upstream["summary"]
    record[:details] = upstream["details"] if upstream["details"]
    record[:severity] = upstream["severity"] if upstream["severity"]
    record[:upstream] = ([vuln_id] + Array(upstream["aliases"])).uniq
    if (refs = upstream["references"])
      # OSV.dev merges NVD and cve.org reference lists without normalising
      # percent-encoding, so the same URL can appear twice (e.g. `%40` vs
      # `@`). Collapse those while keeping the same URL under distinct
      # `type` values, which the schema allows and which carries meaning.
      record[:references] = refs.uniq do |r|
        [r["type"], URI::RFC2396_PARSER.unescape(r["url"].to_s)]
      end
    end
  end

  record
end

.run(annotated, dir, first_fixed: nil, now: Time.now.utc) ⇒ Array<String>

This method is part of a private API. This method may only be used in the Homebrew/brew repository. Third parties should avoid using this method if possible, as it may be removed or changed without warning.

annotated is a list of [formula, serialized_patches] pairs. The patches are passed in rather than read from the formula so callers can supply the union across OS/architecture variations (a patch inside an on_linux/on_intel block only appears in Formula#serialized_patches under the matching SimulateSystem).

first_fixed, when given, is called (formula, vuln_id) -> String? for records with no existing file to derive an accurate fixed boundary (e.g. via FormulaVersions git history); existing records preserve their on-disk ranges regardless.

Parameters:

Returns:



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# File 'vulns/osv_export.rb', line 54

def self.run(annotated, dir, first_fixed: nil, now: Time.now.utc)
  FileUtils.mkdir_p(dir)
  written = []
  upstream_cache = T.let({}, T::Hash[String, T.any(T::Hash[String, T.untyped], Symbol)])

  annotated.each do |formula, patches|
    Scanner.resolved_ids(patches).each do |vuln_id|
      upstream = upstream_cache.fetch(vuln_id) { upstream_cache[vuln_id] = fetch_upstream(vuln_id) }
      path = File.join(dir, "#{ID_PREFIX}-#{formula.name}-#{vuln_id}.json")
      existing = File.file?(path)
      # A transient OSV outage would otherwise strip summary/severity/etc.
      # from an existing enriched record; leave it untouched instead.
      next if upstream == :failed && existing

      fixed = (first_fixed&.call(formula, vuln_id) unless existing) || formula.pkg_version.to_s
      record = record_for(formula, vuln_id, patches:, fixed:,
                          upstream: upstream.is_a?(Hash) ? upstream : nil, now:)
      merged = merge_existing(path, record)
      next if merged.nil?

      File.write(path, "#{JSON.pretty_generate(merged)}\n")
      written << path
    end
  end

  written
end