fix: consider vendored golang packages in module attribution (#5093)

Signed-off-by: Keith Zantow <kzantow@gmail.com>

syft/pkg/cataloger/golang/symbols.go

@@ -16,6 +16,10 @@ import (
 // mainPackage is the import path the linker assigns to the binary's main package.
 const mainPackage = "main"
 
+// vendorPrefix is the import-path prefix carried by vendored packages (e.g. from `go mod vendor`, or the
+// standard library's own vendored dependencies such as "vendor/golang.org/x/net/http2").
+const vendorPrefix = "vendor/"
+
 // binarySymbol represents a single function symbol extracted from a go binary's pclntab.
 type binarySymbol struct {
 	// packagePath is the import path of the package that owns the symbol (e.g. "github.com/foo/bar/internal/baz")
@@ -319,8 +323,13 @@ func readPclntab(r io.ReaderAt) (pclntab []byte, textStart uint64, err error) {
 // "(*T).M"). Symbols from the "main" package are attributed to the main module and keyed by the "main"
 // import path the linker assigns. Standard-library symbols (which belong to no module) are collected
 // separately and returned as the second value, grouped by import path, so they can be attached to the
-// synthetic "stdlib" package. Compiler/runtime-internal symbols that are neither module-owned nor a
-// recognizable stdlib import path are dropped.
+// synthetic "stdlib" package. Vendored packages carry a "vendor/" import-path prefix: such symbols match
+// both modules whose own path carries the prefix and modules without it (matched with the prefix trimmed),
+// and the prefix is retained in the group key only when the owning module itself is named "vendor/...".
+// Module-less vendored packages (the stdlib's own vendored dependencies, e.g.
+// "vendor/golang.org/x/net/http2") are dropped: stdlib vulnerabilities seem to be reported against the public
+// packages (e.g. "crypto/x509"), not the vendored internal copies. Compiler/runtime-internal symbols that
+// are neither module-owned nor a recognizable stdlib import path are likewise dropped.
 func moduleSymbols(symbols []binarySymbol, main *debug.Module, deps []*debug.Module) (byModule map[string]map[string][]string, stdlib map[string][]string) {
 	if len(symbols) == 0 {
 		return nil, nil
@@ -348,16 +357,17 @@ func moduleSymbols(symbols []binarySymbol, main *debug.Module, deps []*debug.Mod
 			attrPath = main.Path
 		}
 
-		var best string
-		for _, modPath := range modulePaths {
-			if len(modPath) > len(best) && (attrPath == modPath || strings.HasPrefix(attrPath, modPath+"/")) {
-				best = modPath
-			}
+		best := findBestMatch(modulePaths, attrPath)
+
+		// the vendor/ prefix is only retained when the owning module itself is named "vendor/...";
+		// in all other cases (non-vendored modules and vendored stdlib) the recorded import path is trimmed
+		if !strings.HasPrefix(best, vendorPrefix) {
+			importPath = strings.TrimPrefix(importPath, vendorPrefix)
 		}
 
 		local := localSymbolName(sym.name, importPath)
 		if best == "" {
-			if importPath != mainPackage && isStandardImportPath(importPath) {
+			if importPath != mainPackage && isStandardImportPath(importPath) { // drop stdlib vendored packages
 				stdlib[importPath] = append(stdlib[importPath], local)
 			}
 			continue
@@ -379,11 +389,36 @@ func moduleSymbols(symbols []binarySymbol, main *debug.Module, deps []*debug.Mod
 	return results, stdlib
 }
 
+// findBestMatch returns the module path that owns the given package path taking into account vendor/ prefixes: a vendor/ import path
+// will take precedence and continue to match, non-vendored imports will match against their vendored equivalent
+func findBestMatch(modulePaths []string, importPath string) string {
+	trimmedPath, trimmed := strings.CutPrefix(importPath, vendorPrefix)
+	candidatePaths := []string{importPath, trimmedPath}
+	if !trimmed {
+		candidatePaths = candidatePaths[:1]
+	}
+
+	var best string
+	for _, candidate := range candidatePaths {
+		for _, modPath := range modulePaths {
+			// the prefix must end at a path-segment boundary in candidate, so that e.g. the module
+			// "github.com/foo/bar" matches the package "github.com/foo/bar/baz" but not "github.com/foo/barbaz"
+			if len(modPath) > len(best) && strings.HasPrefix(candidate, modPath) && (candidate == modPath || candidate[len(modPath)] == '/') {
+				best = modPath
+			}
+		}
+	}
+	return best
+}
+
 // localSymbolName strips the owning package's import path prefix from a fully qualified symbol name, e.g.
 // "github.com/foo/bar.(*T).M" with import path "github.com/foo/bar" becomes "(*T).M". The name is returned
 // unchanged when it does not carry the expected prefix.
 func localSymbolName(name, importPath string) string {
-	if importPath != "" && strings.HasPrefix(name, importPath+".") {
+	if !strings.HasPrefix(importPath, vendorPrefix) {
+		name = strings.TrimPrefix(name, vendorPrefix)
+	}
+	if len(importPath) < len(name) && strings.HasPrefix(name, importPath) && name[len(importPath)] == '.' {
 		return name[len(importPath)+1:]
 	}
 	return name

syft/pkg/cataloger/golang/symbols_test.go

@@ -16,6 +16,8 @@ func Test_moduleSymbols(t *testing.T) {
 	deps := []*debug.Module{
 		{Path: "github.com/foo/bar"},
 		{Path: "github.com/foo/bar/v2"},
+		{Path: "vendor/github.com/vendored/mod"},
+		{Path: "github.com/vendored/mod"},
 		nil,
 	}
 
@@ -74,6 +76,63 @@ func Test_moduleSymbols(t *testing.T) {
 				"runtime":      {"main"},
 			},
 		},
+		{
+			name: "vendored packages match non-vendored modules and are recorded under the canonical import path",
+			symbols: []binarySymbol{
+				{packagePath: "vendor/github.com/foo/bar", name: "vendor/github.com/foo/bar.Parse"},
+				{packagePath: "vendor/github.com/foo/bar/internal/util", name: "vendor/github.com/foo/bar/internal/util.(*Helper).Do"},
+			},
+			expected: map[string]map[string][]string{
+				"github.com/foo/bar": {
+					"github.com/foo/bar":               {"Parse"},
+					"github.com/foo/bar/internal/util": {"(*Helper).Do"},
+				},
+			},
+		},
+		{
+			name: "stdlib-vendored packages are dropped",
+			symbols: []binarySymbol{
+				{packagePath: "vendor/golang.org/x/net/http2", name: "vendor/golang.org/x/net/http2.(*Framer).ReadFrame"},
+			},
+			expected: map[string]map[string][]string{},
+		},
+		{
+			name: "modules whose own path carries the vendor/ prefix match exactly and win over the trimmed match",
+			symbols: []binarySymbol{
+				{packagePath: "vendor/github.com/vendored/mod", name: "vendor/github.com/vendored/mod.Run"},
+				{packagePath: "github.com/vendored/mod", name: "github.com/vendored/mod.Run"},
+			},
+			expected: map[string]map[string][]string{
+				"vendor/github.com/vendored/mod": {
+					"vendor/github.com/vendored/mod": {"Run"},
+				},
+				"github.com/vendored/mod": {
+					"github.com/vendored/mod": {"Run"},
+				},
+			},
+		},
+		{
+			name: "vendored and unvendored symbols for the same package are merged and deduplicated under the canonical import path",
+			symbols: []binarySymbol{
+				{packagePath: "github.com/foo/bar", name: "github.com/foo/bar.Parse"},
+				{packagePath: "vendor/github.com/foo/bar", name: "vendor/github.com/foo/bar.Parse"},
+			},
+			expected: map[string]map[string][]string{
+				"github.com/foo/bar": {
+					"github.com/foo/bar": {"Parse"},
+				},
+			},
+		},
+		{
+			// "github.com/foo/barbaz" shares a string prefix with the "github.com/foo/bar" module but not a
+			// path-segment boundary, so it must not be attributed to it (and, having a dotted first element,
+			// it is not a stdlib path either — it is dropped)
+			name: "module paths only match the package path at a path-segment boundary",
+			symbols: []binarySymbol{
+				{packagePath: "github.com/foo/barbaz", name: "github.com/foo/barbaz.Parse"},
+			},
+			expected: map[string]map[string][]string{},
+		},
 		{
 			name: "duplicate symbols are deduplicated",
 			symbols: []binarySymbol{
@@ -291,6 +350,9 @@ func Test_packagePathFromSymbolName(t *testing.T) {
 		// module paths that begin with "go." are not compiler-generated
 		{"go.uber.org/zap.(*Logger).Info", "go.uber.org/zap"},
 		{"go.opentelemetry.io/otel.Tracer", "go.opentelemetry.io/otel"},
+		// vendored packages retain their "vendor/" import-path prefix in symbol names
+		{"vendor/golang.org/x/net/http2.(*Framer).ReadFrame", "vendor/golang.org/x/net/http2"},
+		{"vendor/github.com/foo/bar.Parse", "vendor/github.com/foo/bar"},
 	}
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {