fix(rust): omit Cargo PURLs for local packages (#5105)

Signed-off-by: Enes Deniz <142517728+3nesdeniz@users.noreply.github.com>

Author: 3nesdeniz

syft/pkg/cataloger/rust/package.go

@@ -14,7 +14,7 @@ func newPackageFromCargoMetadata(m pkg.RustCargoLockEntry, locations ...file.Loc
 		Name:      m.Name,
 		Version:   m.Version,
 		Locations: file.NewLocationSet(locations...),
-		PURL:      packageURL(m.Name, m.Version),
+		PURL:      cargoLockPackageURL(m),
 		Language:  pkg.Rust,
 		Type:      pkg.RustPkg,
 		Metadata:  m,
@@ -25,6 +25,18 @@ func newPackageFromCargoMetadata(m pkg.RustCargoLockEntry, locations ...file.Loc
 	return p
 }
 
+func cargoLockPackageURL(m pkg.RustCargoLockEntry) string {
+	// Cargo omits source for packages resolved from the local workspace or a
+	// path dependency. A cargo PURL without a repository qualifier identifies
+	// a package on crates.io, so emitting one for a local package can cause
+	// downstream scanners to match unrelated registry vulnerabilities.
+	if m.Source == "" {
+		return ""
+	}
+
+	return packageURL(m.Name, m.Version)
+}
+
 func newPackageFromAudit(dep *rustaudit.Package, locations ...file.Location) pkg.Package {
 	p := pkg.Package{
 		Name:      dep.Name,

syft/pkg/cataloger/rust/package_test.go

@@ -4,6 +4,8 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+
+	"github.com/anchore/syft/syft/pkg"
 )
 
 func Test_packageURL(t *testing.T) {
@@ -31,3 +33,34 @@ func Test_packageURL(t *testing.T) {
 		})
 	}
 }
+
+func TestNewPackageFromCargoMetadataPURL(t *testing.T) {
+	tests := []struct {
+		name   string
+		source string
+		want   string
+	}{
+		{
+			name:   "crates.io package",
+			source: "registry+https://github.com/rust-lang/crates.io-index",
+			want:   "pkg:cargo/telemetry@0.1.0",
+		},
+		{
+			name:   "local path package",
+			source: "",
+			want:   "",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := newPackageFromCargoMetadata(pkg.RustCargoLockEntry{
+				Name:    "telemetry",
+				Version: "0.1.0",
+				Source:  tt.source,
+			})
+
+			assert.Equal(t, tt.want, got.PURL)
+		})
+	}
+}

syft/pkg/cataloger/rust/parse_cargo_lock_test.go

@@ -351,7 +351,7 @@ func TestCargoLockWithGitDependencies(t *testing.T) {
 	helloWorld := pkg.Package{
 		Name:      "hello_world",
 		Version:   "0.1.0",
-		PURL:      "pkg:cargo/hello_world@0.1.0",
+		PURL:      "",
 		Locations: locations,
 		Language:  pkg.Rust,
 		Type:      pkg.RustPkg,
@@ -673,6 +673,77 @@ func TestCargoLockWithGitDependencies(t *testing.T) {
 	pkgtest.TestFileParser(t, fixture, parseCargoLock, expectedPkgs, expectedRelationships)
 }
 
+func TestCargoLockWithPathDependencies(t *testing.T) {
+	fixture := "testdata/path-deps/Cargo.lock"
+	locations := file.NewLocationSet(file.NewLocation(fixture))
+
+	app := pkg.Package{
+		Name:      "app",
+		Version:   "1.0.0",
+		Locations: locations,
+		Language:  pkg.Rust,
+		Type:      pkg.RustPkg,
+		Licenses:  pkg.NewLicenseSet(),
+		Metadata: pkg.RustCargoLockEntry{
+			Name:    "app",
+			Version: "1.0.0",
+			Dependencies: []string{
+				"memchr",
+				"telemetry",
+			},
+		},
+	}
+	memchr := pkg.Package{
+		Name:      "memchr",
+		Version:   "2.7.4",
+		PURL:      "pkg:cargo/memchr@2.7.4",
+		Locations: locations,
+		Language:  pkg.Rust,
+		Type:      pkg.RustPkg,
+		Licenses:  pkg.NewLicenseSet(),
+		Metadata: pkg.RustCargoLockEntry{
+			Name:         "memchr",
+			Version:      "2.7.4",
+			Source:       "registry+https://github.com/rust-lang/crates.io-index",
+			Checksum:     "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3",
+			Dependencies: []string{},
+		},
+	}
+	telemetry := pkg.Package{
+		Name:      "telemetry",
+		Version:   "0.1.0",
+		Locations: locations,
+		Language:  pkg.Rust,
+		Type:      pkg.RustPkg,
+		Licenses:  pkg.NewLicenseSet(),
+		Metadata: pkg.RustCargoLockEntry{
+			Name:         "telemetry",
+			Version:      "0.1.0",
+			Dependencies: []string{},
+		},
+	}
+
+	expectedPkgs := []pkg.Package{
+		app,
+		memchr,
+		telemetry,
+	}
+	expectedRelationships := []artifact.Relationship{
+		{
+			From: memchr,
+			To:   app,
+			Type: artifact.DependencyOfRelationship,
+		},
+		{
+			From: telemetry,
+			To:   app,
+			Type: artifact.DependencyOfRelationship,
+		},
+	}
+
+	pkgtest.TestFileParser(t, fixture, parseCargoLock, expectedPkgs, expectedRelationships)
+}
+
 func TestCargoLockDependencySpecification(t *testing.T) {
 	tests := []struct {
 		name     string