From b618b84bac2cd7098abf8ee8742bd662ed617804 Mon Sep 17 00:00:00 2001
From: Keith Zantow <kzantow@gmail.com>
Date: Wed, 22 Dec 2021 13:27:41 -0500
Subject: [PATCH] Ignore explicit list of log4j false positive matches (#559)

---
 grype/match/explicit_ignores.go      | 55 ++++++++++++++++
 grype/match/explicit_ignores_test.go | 94 ++++++++++++++++++++++++++++
 grype/matcher/controller.go          |  2 +
 3 files changed, 151 insertions(+)
 create mode 100644 grype/match/explicit_ignores.go
 create mode 100644 grype/match/explicit_ignores_test.go

diff --git a/grype/match/explicit_ignores.go b/grype/match/explicit_ignores.go
new file mode 100644
index 00000000..12a4e6de
--- /dev/null
+++ b/grype/match/explicit_ignores.go
@@ -0,0 +1,55 @@
+package match
+
+import "github.com/anchore/grype/internal/log"
+
+var explicitIgnoreRules []IgnoreRule
+
+func init() {
+	type ignoreValues struct {
+		typ             string
+		vulnerabilities []string
+		packages        []string
+	}
+
+	var explicitIgnores = []ignoreValues{
+		// Based on https://github.com/anchore/grype/issues/552, which includes a reference to the
+		// https://github.com/mergebase/log4j-samples collection, we want to filter these explicitly:
+		{"java-archive",
+			[]string{"CVE-2021-44228", "CVE-2021-45046", "GHSA-jfh8-c2jp-5v3q", "GHSA-7rjr-3q55-vv33"},
+			[]string{"log4j-api", "log4j-slf4j-impl", "log4j-to-slf4j", "log4j-1.2-api", "log4j-detector", "log4j-over-slf4j", "slf4j-log4j12"},
+		},
+	}
+
+	for _, ignore := range explicitIgnores {
+		for _, vulnerability := range ignore.vulnerabilities {
+			for _, packageName := range ignore.packages {
+				explicitIgnoreRules = append(explicitIgnoreRules, IgnoreRule{
+					Vulnerability: vulnerability,
+					Package: IgnoreRulePackage{
+						Name: packageName,
+						Type: ignore.typ,
+					},
+				})
+			}
+		}
+	}
+}
+
+// ApplyExplicitIgnoreRules This will filter out matches that are defined above, in the
+// explicitIgnores list
+func ApplyExplicitIgnoreRules(matches Matches) Matches {
+	matches, ignored := ApplyIgnoreRules(matches, explicitIgnoreRules)
+
+	if len(ignored) > 0 {
+		log.Debugf("Removed %d explicit vulnerability matches:", len(ignored))
+		for idx, i := range ignored {
+			branch := "├──"
+			if idx == len(ignored)-1 {
+				branch = "└──"
+			}
+			log.Debugf("  %s %s : %s", branch, i.Match.Vulnerability.ID, i.Package.PURL)
+		}
+	}
+
+	return matches
+}
diff --git a/grype/match/explicit_ignores_test.go b/grype/match/explicit_ignores_test.go
new file mode 100644
index 00000000..f9d13bb9
--- /dev/null
+++ b/grype/match/explicit_ignores_test.go
@@ -0,0 +1,94 @@
+package match
+
+import (
+	"testing"
+
+	"github.com/anchore/grype/grype/pkg"
+	"github.com/anchore/grype/grype/vulnerability"
+	syftPkg "github.com/anchore/syft/syft/pkg"
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_ApplyExplicitIgnoreRules(t *testing.T) {
+	type cvePkg struct {
+		cve string
+		pkg string
+	}
+	tests := []struct {
+		name     string
+		typ      syftPkg.Type
+		matches  []cvePkg
+		expected []string
+	}{
+		// some explicit log4j-related data:
+		// "CVE-2021-44228", "CVE-2021-45046", "GHSA-jfh8-c2jp-5v3q", "GHSA-7rjr-3q55-vv33",
+		// "log4j-api", "log4j-slf4j-impl", "log4j-to-slf4j", "log4j-1.2-api",
+		{
+			name: "keeps non-matching packages",
+			typ:  "java-archive",
+			matches: []cvePkg{
+				{"CVE-2021-44228", "log4j-core"},
+				{"CVE-2021-43452", "foo-tool"},
+			},
+			expected: []string{"log4j-core", "foo-tool"},
+		},
+		{
+			name: "keeps non-matching CVEs",
+			typ:  "java-archive",
+			matches: []cvePkg{
+				{"CVE-2021-428", "log4j-api"},
+				{"CVE-2021-43452", "foo-tool"},
+			},
+			expected: []string{"log4j-api", "foo-tool"},
+		},
+		{
+			name: "filters only matching CVE and package",
+			typ:  "java-archive",
+			matches: []cvePkg{
+				{"CVE-2021-44228", "log4j-api"},
+				{"CVE-2021-44228", "log4j-core"},
+			},
+			expected: []string{"log4j-core"},
+		},
+		{
+			name: "filters all matching CVEs and packages",
+			typ:  "java-archive",
+			matches: []cvePkg{
+				{"GHSA-jfh8-c2jp-5v3q", "log4j-api"},
+				{"GHSA-jfh8-c2jp-5v3q", "log4j-slf4j-impl"},
+			},
+			expected: []string{},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			matches := Matches{
+				byPackage: make(map[pkg.ID][]Match),
+			}
+
+			for _, cp := range test.matches {
+				matches.byPackage[pkg.ID(cp.pkg)] = []Match{
+					{
+						Package: pkg.Package{
+							Name: cp.pkg,
+							Type: test.typ,
+						},
+						Vulnerability: vulnerability.Vulnerability{
+							ID: cp.cve,
+						},
+					},
+				}
+			}
+
+			filtered := ApplyExplicitIgnoreRules(matches)
+
+			var found []string
+			for match := range filtered.Enumerate() {
+				found = append(found, match.Package.Name)
+
+			}
+			assert.ElementsMatch(t, test.expected, found)
+		})
+	}
+}
diff --git a/grype/matcher/controller.go b/grype/matcher/controller.go
index f8f06a16..bae86b6b 100644
--- a/grype/matcher/controller.go
+++ b/grype/matcher/controller.go
@@ -108,6 +108,8 @@ func (c *controller) findMatches(provider vulnerability.Provider, d *distro.Dist
 	packagesProcessed.SetCompleted()
 	vulnerabilitiesDiscovered.SetCompleted()
 
+	res = match.ApplyExplicitIgnoreRules(res)
+
 	return res
 }