fix(sbom): fix incompliant license format for spdx (#3335)

pkg/fanal/analyzer/pkg/dpkg/copyright.go

@@ -87,6 +87,10 @@ func (a *dpkgLicenseAnalyzer) parseCopyright(r dio.ReadSeekerAt) ([]types.Licens
 			// Machine-readable format
 			// cf. https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/#:~:text=The%20debian%2Fcopyright%20file%20must,in%20the%20Debian%20Policy%20Manual.
 			l := strings.TrimSpace(line[8:])
+
+			// Very rarely has below phrases
+			l = strings.TrimPrefix(l, "The main library is licensed under ")
+			l = strings.TrimSuffix(l, " license")
 			if len(l) > 0 {
 				// Split licenses without considering "and"/"or"
 				// examples:

pkg/licensing/expression/expression.go

@@ -0,0 +1,74 @@
+package expression
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/aquasecurity/trivy/pkg/licensing/expression/lexer"
+	"github.com/aquasecurity/trivy/pkg/licensing/expression/parser"
+)
+
+type Operator string
+
+const (
+	AND  Operator = "AND"
+	OR   Operator = "OR"
+	WITH Operator = "WITH"
+)
+
+func (o Operator) String() string {
+	return fmt.Sprintf(" %s ", string(o))
+}
+
+func Normalize(license string, fn ...parser.NormalizeFunc) string {
+	lex := lexer.New(license)
+	licenseParser := parser.New(lex).RegisterNormalizeFunc(
+		fn...,
+	)
+	expression, err := licenseParser.Parse()
+	if err != nil {
+		return license
+	}
+	return licenseParser.Normalize(expression)
+}
+
+func Join(elems []string, sep Operator) string {
+	var licenses []string
+	for i, license := range elems {
+		var mid Operator
+		if sep == AND {
+			mid = OR
+		} else if sep == OR {
+			mid = AND
+		}
+
+		if i != 0 && strings.Contains(strings.ToUpper(license), mid.String()) {
+			license = fmt.Sprintf("(%s)", license)
+		}
+		licenses = append(licenses, license)
+	}
+
+	return strings.Join(licenses, sep.String())
+}
+
+// NormalizeForSPDX is normalized license-id replace ' ' to '-'.
+// SPDX license MUST NOT be white space between a license-id.
+// There MUST be white space on either side of the operator "WITH".
+// ref: https://spdx.github.io/spdx-spec/v2.3/SPDX-license-expressions
+func NormalizeForSPDX(name string) string {
+	i := strings.Index(strings.ToUpper(name), WITH.String())
+	if i < 0 {
+		return strings.Replace(name, " ", "-", -1)
+	}
+
+	// Convert "WITH" expression split by " " to "-".
+	// examples:
+	// 	GPL-2+ with distribution exception => GPL-2+ with distribution-exception
+	//  GPL-2 with Linux-syscall-note exception => GPL-2 with Linux-syscall-note-exception
+	//  AFL 2.0 with Linux-syscall-note exception => AFL-2.0 with Linux-syscall-note-exception
+	withSection := strings.Replace(name[i+len(WITH.String()):], " ", "-", -1)
+	if i > 0 {
+		return strings.Replace(name[:i], " ", "-", -1) + WITH.String() + withSection
+	}
+	return name
+}

pkg/licensing/expression/expression_test.go

@@ -0,0 +1,83 @@
+package expression
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNormalizeForSPDX(t *testing.T) {
+	tests := []struct {
+		name    string
+		license string
+		want    string
+	}{
+		{
+			name:    "happy path",
+			license: "AFL 2.0",
+			want:    "AFL-2.0",
+		},
+		{
+			name:    "happy path with WITH section",
+			license: "AFL 2.0 with Linux-syscall-note exception",
+			want:    "AFL-2.0 WITH Linux-syscall-note-exception",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equalf(t, tt.want, NormalizeForSPDX(tt.license), "NormalizeWithExpression(%v)", tt.license)
+		})
+	}
+}
+
+func TestJoin(t *testing.T) {
+	tests := []struct {
+		name          string
+		inputElements []string
+		inputOperator Operator
+		expect        string
+	}{
+		{
+			name:          "happy path single license",
+			inputElements: []string{"MIT"},
+			inputOperator: AND,
+			expect:        "MIT",
+		},
+		{
+			name:          "happy path multi license",
+			inputElements: []string{"MIT", "GPL1.0"},
+			inputOperator: AND,
+			expect:        "MIT AND GPL1.0",
+		},
+		{
+			name:          "happy path multi license with AND operator",
+			inputElements: []string{"MIT", "GPL1.0 AND GPL2.0"},
+			inputOperator: AND,
+			expect:        "MIT AND GPL1.0 AND GPL2.0",
+		},
+		{
+			name:          "happy path multi license with OR operator",
+			inputElements: []string{"MIT", "GPL1.0 OR GPL2.0"},
+			inputOperator: OR,
+			expect:        "MIT OR GPL1.0 OR GPL2.0",
+		},
+		{
+			name:          "happy path multi license with OR operator, separator AND",
+			inputElements: []string{"MIT", "GPL1.0 OR GPL2.0"},
+			inputOperator: AND,
+			expect:        "MIT AND (GPL1.0 OR GPL2.0)",
+		},
+		{
+			name:          "happy path multi license with AND operator, separator OR",
+			inputElements: []string{"MIT", "GPL1.0 AND GPL2.0"},
+			inputOperator: OR,
+			expect:        "MIT OR (GPL1.0 AND GPL2.0)",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := Join(tt.inputElements, tt.inputOperator)
+			assert.Equal(t, tt.expect, got)
+		})
+	}
+}

pkg/licensing/expression/lexer/lexer.go

@@ -0,0 +1,85 @@
+package lexer
+
+import (
+	"github.com/aquasecurity/trivy/pkg/licensing/expression/token"
+)
+
+type Lexer struct {
+	input        string
+	position     int
+	readPosition int
+	ch           byte
+}
+
+func New(input string) *Lexer {
+	l := &Lexer{input: input}
+	l.readChar()
+	return l
+}
+
+func (l *Lexer) NextToken() token.Token {
+	var tok token.Token
+
+	l.skipWhitespace()
+
+	switch l.ch {
+	case 0:
+		tok = newToken(token.EOF, l.ch)
+	case '(':
+		tok = newToken(token.LPAREN, l.ch)
+	case ')':
+		tok = newToken(token.RPAREN, l.ch)
+	default:
+		if isLetter(l.ch) {
+			tok.Literal = l.readIdentifier()
+			tok.Type = token.LookupIdent(tok.Literal)
+			return tok
+		} else {
+			tok = newToken(token.ILLEGAL, l.ch)
+		}
+	}
+	l.readChar()
+	return tok
+}
+
+func isLetter(ch byte) bool {
+	return 'a' <= ch && ch <= 'z' ||
+		'A' <= ch && ch <= 'Z' ||
+		'0' <= ch && ch <= '9' ||
+		ch == '_' ||
+		ch == '+' ||
+		ch == '.' ||
+		ch == '-' ||
+		ch == '/' ||
+		ch == ':' ||
+		ch == '='
+}
+
+func (l *Lexer) readIdentifier() string {
+	position := l.position
+	for isLetter(l.ch) {
+		l.readChar()
+	}
+	return l.input[position:l.position]
+}
+
+func newToken(tokenType token.TokenType, ch byte) token.Token {
+	return token.Token{Type: tokenType, Literal: string(ch)}
+}
+
+func (l *Lexer) skipWhitespace() {
+	for l.ch == ' ' || l.ch == '\t' || l.ch == '\n' || l.ch == '\r' {
+		l.readChar()
+	}
+}
+
+func (l *Lexer) readChar() {
+	if l.readPosition >= len(l.input) {
+		// 0 is ASCII NUL
+		l.ch = 0
+	} else {
+		l.ch = l.input[l.readPosition]
+	}
+	l.position = l.readPosition
+	l.readPosition++
+}

pkg/licensing/expression/lexer/lexer_test.go

@@ -0,0 +1,143 @@
+package lexer
+
+import (
+	"testing"
+
+	"github.com/aquasecurity/trivy/pkg/licensing/expression/token"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNextToken(t *testing.T) {
+	tests := []struct {
+		name              string
+		licenseExpression string
+		expectTokens      []token.Token
+	}{
+		{
+			name:              "empty input",
+			licenseExpression: "",
+			expectTokens: []token.Token{
+				{
+					Type:    token.EOF,
+					Literal: string(byte(0)),
+				},
+			},
+		},
+		{
+			name:              "single ident",
+			licenseExpression: "GPL1.0+",
+			expectTokens: []token.Token{
+				{
+					Type:    token.IDENT,
+					Literal: "GPL1.0+",
+				},
+			},
+		},
+		{
+			name:              "multi ident",
+			licenseExpression: "Public Domain",
+			expectTokens: []token.Token{
+				{
+					Type:    token.IDENT,
+					Literal: "Public",
+				},
+				{
+					Type:    token.IDENT,
+					Literal: "Domain",
+				},
+			},
+		},
+		{
+			name:              "AND OR operator",
+			licenseExpression: "Public Domain AND GPL1.0+ OR GPL2.0_or_later",
+			expectTokens: []token.Token{
+				{
+					Type:    token.IDENT,
+					Literal: "Public",
+				},
+				{
+					Type:    token.IDENT,
+					Literal: "Domain",
+				},
+				{
+					Type:    token.AND,
+					Literal: "AND",
+				},
+				{
+					Type:    token.IDENT,
+					Literal: "GPL1.0+",
+				},
+				{
+					Type:    token.OR,
+					Literal: "OR",
+				},
+				{
+					Type:    token.IDENT,
+					Literal: "GPL2.0_or_later",
+				},
+			},
+		},
+		{
+			name:              "PAREN operator",
+			licenseExpression: "(GPL1.0+ OR GPL2.0)",
+			expectTokens: []token.Token{
+				{
+					Type:    token.LPAREN,
+					Literal: "(",
+				},
+				{
+					Type:    token.IDENT,
+					Literal: "GPL1.0+",
+				},
+				{
+					Type:    token.OR,
+					Literal: "OR",
+				},
+				{
+					Type:    token.IDENT,
+					Literal: "GPL2.0",
+				},
+				{
+					Type:    token.RPAREN,
+					Literal: ")",
+				},
+			},
+		},
+		{
+			name:              "illegal string",
+			licenseExpression: "GPL1.0+" + string(byte(0x20)) + "あ" + "🇯🇵" + "AND LGPL1.0",
+			expectTokens: []token.Token{
+				{
+					Type:    token.IDENT,
+					Literal: "GPL1.0+",
+				},
+				{
+					Type:    token.AND,
+					Literal: "AND",
+				},
+				{
+					Type:    token.IDENT,
+					Literal: "LGPL1.0+",
+				},
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		l := New(tt.licenseExpression)
+		for _, expect := range tt.expectTokens {
+			tok := l.NextToken()
+
+			// Skip literal
+			if tok.Type == token.ILLEGAL {
+				continue
+			}
+
+			t.Run(tt.name, func(t *testing.T) {
+				assert.Equal(t, expect.Type, tok.Type)
+				assert.Equal(t, expect.Literal, tok.Literal)
+			})
+		}
+	}
+}

pkg/licensing/expression/parser/parser.go

@@ -0,0 +1,102 @@
+package parser
+
+import (
+	"fmt"
+	"strings"
+
+	"golang.org/x/xerrors"
+
+	"github.com/aquasecurity/trivy/pkg/licensing/expression/lexer"
+	"github.com/aquasecurity/trivy/pkg/licensing/expression/token"
+)
+
+var (
+	ErrInvalidExpression = xerrors.New("invalid expression error")
+)
+
+type Parser struct {
+	lex         *lexer.Lexer
+	normalizeFn []NormalizeFunc
+}
+
+type LicenseExpression struct {
+	Node     Node
+	Operator string
+	Next     *LicenseExpression
+}
+
+type Node struct {
+	License           string
+	LicenseExpression *LicenseExpression
+}
+
+type NormalizeFunc func(n string) string
+
+func New(lex *lexer.Lexer) *Parser {
+	return &Parser{
+		lex: lex,
+	}
+}
+
+func (p *Parser) RegisterNormalizeFunc(fn ...NormalizeFunc) *Parser {
+	p.normalizeFn = append(p.normalizeFn, fn...)
+	return p
+}
+
+func (p *Parser) Parse() (*LicenseExpression, error) {
+	root := &LicenseExpression{}
+	cursor := root
+	stack := Stack{}
+
+	for tok := p.lex.NextToken(); tok.Type != token.EOF; tok = p.lex.NextToken() {
+		switch tok.Type {
+		case token.IDENT:
+			if cursor.Node.License == "" {
+				cursor.Node = Node{License: tok.Literal}
+			} else {
+				cursor.Node.License = fmt.Sprintf("%s %s", cursor.Node.License, tok.Literal)
+			}
+		case token.AND, token.OR:
+			cursor.Operator = string(tok.Type)
+			cursor.Next = &LicenseExpression{}
+			cursor = cursor.Next
+		case token.LPAREN:
+			p := Pair{root: root, cursor: cursor, bracket: tok.Type}
+			stack.Push(p)
+			root = &LicenseExpression{}
+			cursor = root
+		case token.RPAREN:
+			e := stack.Pop()
+			if e.bracket == token.LPAREN && tok.Type != token.RPAREN {
+				return nil, ErrInvalidExpression
+			}
+			e.cursor.Node.LicenseExpression = root
+			cursor = e.cursor
+			root = e.root
+		}
+	}
+	if !stack.IsEmpty() {
+		return nil, ErrInvalidExpression
+	}
+	return root, nil
+}
+
+func (p *Parser) Normalize(l *LicenseExpression) string {
+	cursor := l
+
+	var str string
+	for ; cursor != nil; cursor = cursor.Next {
+		str = strings.Join([]string{str, p.normalize(cursor.Node), cursor.Operator}, " ")
+	}
+	return strings.TrimSpace(str)
+}
+
+func (p *Parser) normalize(n Node) string {
+	if n.LicenseExpression != nil {
+		return fmt.Sprintf("( %s )", p.Normalize(n.LicenseExpression))
+	}
+	for _, fn := range p.normalizeFn {
+		n.License = fn(n.License)
+	}
+	return n.License
+}

pkg/licensing/expression/parser/parser_test.go

@@ -0,0 +1,189 @@
+package parser
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/aquasecurity/trivy/pkg/licensing/expression/lexer"
+)
+
+func TestParse(t *testing.T) {
+	tests := []struct {
+		name      string
+		input     string
+		normFunc  []NormalizeFunc
+		expect    *LicenseExpression
+		expectStr string
+		expectErr string
+	}{
+		{
+			name:  "happy path single license",
+			input: "Public Domain",
+			expect: &LicenseExpression{
+				Node: Node{
+					License: "Public Domain",
+				},
+			},
+			expectStr: "Public Domain",
+		},
+		{
+			name:  "happy path tag:value license",
+			input: "DocumentRef-spdx-tool-1.2:LicenseRef-MIT-Style-2",
+			expect: &LicenseExpression{
+				Node: Node{
+					License: "DocumentRef-spdx-tool-1.2:LicenseRef-MIT-Style-2",
+				},
+			},
+			expectStr: "DocumentRef-spdx-tool-1.2:LicenseRef-MIT-Style-2",
+		},
+		{
+			name:  "happy path single license with norm func",
+			input: "Public Domain with exception",
+			expect: &LicenseExpression{
+				Node: Node{
+					License: "Public Domain with exception",
+				},
+			},
+			normFunc: []NormalizeFunc{
+				func(n string) string {
+					return strings.Replace(n, " ", "_", -1)
+				},
+				func(n string) string {
+					if n == "Public_Domain_with_exception" {
+						return "Unlicense"
+					}
+					return n
+				},
+			},
+			expectStr: "Unlicense",
+		},
+		{
+			name:  "happy path 2",
+			input: "Public ._+-",
+			expect: &LicenseExpression{
+				Node: Node{
+					License: "Public ._+-",
+				},
+			},
+			expectStr: "Public ._+-",
+		},
+		{
+			name:  "happy path multi license",
+			input: "Public Domain AND ( GPLv2+ or AFL ) AND LGPLv2+ with distribution exceptions",
+			expect: &LicenseExpression{
+				Node: Node{
+					License: "Public Domain",
+				},
+				Operator: "AND",
+				Next: &LicenseExpression{
+					Node: Node{
+						LicenseExpression: &LicenseExpression{
+							Node: Node{
+								License: "GPLv2+",
+							},
+							Operator: "OR",
+							Next: &LicenseExpression{
+								Node: Node{
+									License: "AFL",
+								},
+							},
+						},
+					},
+					Operator: "AND",
+					Next: &LicenseExpression{
+						Node: Node{
+							License: "LGPLv2+ with distribution exceptions",
+						},
+					},
+				},
+			},
+			expectStr: "Public Domain AND ( GPLv2+ OR AFL ) AND LGPLv2+ with distribution exceptions",
+		},
+		{
+			name:  "happy path nested license",
+			input: "Public Domain AND ( GPLv2+ or AFL AND ( CC0 or LGPL1.0) )",
+			expect: &LicenseExpression{
+				Node: Node{
+					License: "Public Domain",
+				},
+				Operator: "AND",
+				Next: &LicenseExpression{
+					Node: Node{
+						LicenseExpression: &LicenseExpression{
+							Node: Node{
+								License: "GPLv2+",
+							},
+							Operator: "OR",
+							Next: &LicenseExpression{
+								Node: Node{
+									License: "AFL",
+								},
+								Operator: "AND",
+								Next: &LicenseExpression{
+									Node: Node{
+										LicenseExpression: &LicenseExpression{
+											Node: Node{
+												License: "CC0",
+											},
+											Operator: "OR",
+											Next: &LicenseExpression{
+												Node: Node{
+													License: "LGPL1.0",
+												},
+											},
+										},
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			expectStr: "Public Domain AND ( GPLv2+ OR AFL AND ( CC0 OR LGPL1.0 ) )",
+		},
+		{
+			name:  "happy path 2",
+			input: "( GPLv2+ or CC0 )",
+			expect: &LicenseExpression{
+				Node: Node{
+					LicenseExpression: &LicenseExpression{
+						Node: Node{
+							License: "GPLv2+",
+						},
+						Operator: "OR",
+						Next: &LicenseExpression{
+							Node: Node{
+								License: "CC0",
+							},
+						},
+					},
+				},
+			},
+			expectStr: "( GPLv2+ OR CC0 )",
+		},
+		{
+			name:      "bad path close bracket not found",
+			input:     "Public Domain AND ( GPLv2+ ",
+			expectErr: "invalid expression error",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			l := lexer.New(tt.input)
+			p := New(l).RegisterNormalizeFunc(tt.normFunc...)
+
+			got, err := p.Parse()
+			if tt.expectErr != "" {
+				assert.Equal(t, err.Error(), tt.expectErr)
+				return
+			}
+
+			require.NoError(t, err)
+			assert.Equal(t, tt.expect, got)
+			assert.Equal(t, tt.expectStr, p.Normalize(got))
+		})
+	}
+}

pkg/licensing/expression/parser/stack.go

@@ -0,0 +1,28 @@
+package parser
+
+import (
+	"github.com/aquasecurity/trivy/pkg/licensing/expression/token"
+)
+
+type Pair struct {
+	root    *LicenseExpression
+	cursor  *LicenseExpression
+	bracket token.TokenType
+}
+
+type Stack []Pair
+
+func (s *Stack) Push(x Pair) {
+	*s = append(*s, x)
+}
+
+func (s *Stack) Pop() Pair {
+	l := len(*s)
+	x := (*s)[l-1]
+	*s = (*s)[:l-1]
+	return x
+}
+
+func (s *Stack) IsEmpty() bool {
+	return len(*s) == 0
+}

pkg/licensing/expression/token/token.go

@@ -0,0 +1,37 @@
+package token
+
+import (
+	"strings"
+)
+
+const (
+	ILLEGAL = "ILLEGAL"
+	EOF     = "EOF"
+
+	IDENT = "IDENT"
+
+	LPAREN = "("
+	RPAREN = ")"
+
+	AND = "AND"
+	OR  = "OR"
+)
+
+var keywords = map[string]TokenType{
+	"AND": AND,
+	"OR":  OR,
+}
+
+type TokenType string
+
+type Token struct {
+	Type    TokenType
+	Literal string
+}
+
+func LookupIdent(ident string) TokenType {
+	if tok, ok := keywords[strings.ToUpper(ident)]; ok {
+		return tok
+	}
+	return IDENT
+}

pkg/licensing/normalize.go

@@ -29,24 +29,27 @@ var mapping = map[string]string{
 	"GPL3+":                          GPL30,
 	"GPL-3+":                         GPL30,
 	"GPL-3.0-OR-LATER":               GPL30,
+	"GPL-3+ WITH AUTOCONF EXCEPTION": GPL30withautoconfexception,
+	"GPL-3+-WITH-BISON-EXCEPTION":    GPL20withbisonexception,
 	"GPL":                            GPL30, // 2? 3?
 
 	// LGPL
-	"LGPL2":     LGPL20,
+	"LGPL2":      LGPL20,
-	"LGPL 2":    LGPL20,
+	"LGPL 2":     LGPL20,
-	"LGPL 2.0":  LGPL20,
+	"LGPL 2.0":   LGPL20,
-	"LGPL-2":    LGPL20,
+	"LGPL-2":     LGPL20,
-	"LGPL2+":    LGPL20,
+	"LGPL2+":     LGPL20,
-	"LGPL-2+":   LGPL20,
+	"LGPL-2+":    LGPL20,
-	"LGPL-2.0+": LGPL20,
+	"LGPL-2.0+":  LGPL20,
-	"LGPL-2.1":  LGPL21,
+	"LGPL-2.1":   LGPL21,
-	"LGPL 2.1":  LGPL21,
+	"LGPL 2.1":   LGPL21,
-	"LGPL-2.1+": LGPL21,
+	"LGPL-2.1+":  LGPL21,
-	"LGPLV2.1+": LGPL21,
+	"LGPLV2.1+":  LGPL21,
-	"LGPL-3":    LGPL30,
+	"LGPL-3":     LGPL30,
-	"LGPL 3":    LGPL30,
+	"LGPL 3":     LGPL30,
-	"LGPL-3+":   LGPL30,
+	"LGPL-3+":    LGPL30,
-	"LGPL":      LGPL30, // 2? 3?
+	"LGPL":       LGPL30, // 2? 3?
+	"GNU LESSER": LGPL30, // 2? 3?
 
 	// MPL
 	"MPL1.0":  MPL10,
@@ -68,6 +71,9 @@ var mapping = map[string]string{
 	"APACHE 2.0": Apache20,
 	"RUBY":       Ruby,
 	"ZLIB":       Zlib,
+
+	// Public Domain
+	"PUBLIC DOMAIN": Unlicense,
 }
 
 func Normalize(name string) string {

pkg/sbom/spdx/marshal.go

@@ -13,6 +13,8 @@ import (
 	"k8s.io/utils/clock"
 
 	ftypes "github.com/aquasecurity/trivy/pkg/fanal/types"
+	"github.com/aquasecurity/trivy/pkg/licensing"
+	"github.com/aquasecurity/trivy/pkg/licensing/expression"
 	"github.com/aquasecurity/trivy/pkg/purl"
 	"github.com/aquasecurity/trivy/pkg/scanner/utils"
 	"github.com/aquasecurity/trivy/pkg/types"
@@ -263,7 +265,7 @@ func (m *Marshaler) langPackage(target, appType string) (spdx.Package2_2, error)
 }
 
 func (m *Marshaler) pkgToSpdxPackage(t string, class types.ResultClass, metadata types.Metadata, pkg ftypes.Package) (spdx.Package2_2, error) {
-	license := getLicense(pkg)
+	license := GetLicense(pkg)
 
 	pkgID, err := calcPkgID(m.hasher, pkg)
 	if err != nil {
@@ -355,12 +357,16 @@ func purlExternalReference(packageURL string) *spdx.PackageExternalReference2_2
 	}
 }
 
-func getLicense(p ftypes.Package) string {
+func GetLicense(p ftypes.Package) string {
 	if len(p.Licenses) == 0 {
 		return "NONE"
 	}
 
-	return strings.Join(p.Licenses, ", ")
+	return expression.Normalize(
+		expression.Join(p.Licenses, expression.AND),
+		licensing.Normalize,
+		expression.NormalizeForSPDX,
+	)
 }
 
 func getDocumentNamespace(r types.Report, m *Marshaler) string {

pkg/sbom/spdx/marshal_test.go

@@ -176,8 +176,8 @@ func TestMarshaler_Marshal(t *testing.T) {
 						PackageSPDXIdentifier:   spdx.ElementID("Package-fd0dc3cf913d5bc3"),
 						PackageName:             "binutils",
 						PackageVersion:          "2.30",
-						PackageLicenseConcluded: "GPLv3+",
+						PackageLicenseConcluded: "GPL-3.0",
-						PackageLicenseDeclared:  "GPLv3+",
+						PackageLicenseDeclared:  "GPL-3.0",
 						PackageExternalReferences: []*spdx.PackageExternalReference2_2{
 							{
 								Category: tspdx.CategoryPackageManager,
@@ -338,8 +338,8 @@ func TestMarshaler_Marshal(t *testing.T) {
 						PackageSPDXIdentifier:   spdx.ElementID("Package-d8dccb186bafaf37"),
 						PackageName:             "acl",
 						PackageVersion:          "2.2.53",
-						PackageLicenseConcluded: "GPLv2+",
+						PackageLicenseConcluded: "GPL-2.0",
-						PackageLicenseDeclared:  "GPLv2+",
+						PackageLicenseDeclared:  "GPL-2.0",
 						PackageExternalReferences: []*spdx.PackageExternalReference2_2{
 							{
 								Category: tspdx.CategoryPackageManager,
@@ -686,3 +686,66 @@ func TestMarshaler_Marshal(t *testing.T) {
 		})
 	}
 }
+
+func Test_GetLicense(t *testing.T) {
+	tests := []struct {
+		name  string
+		input ftypes.Package
+		want  string
+	}{
+		{
+			name: "happy path",
+			input: ftypes.Package{
+				Licenses: []string{
+					"GPLv2+",
+				},
+			},
+			want: "GPL-2.0",
+		},
+		{
+			name: "happy path with multi license",
+			input: ftypes.Package{
+				Licenses: []string{
+					"GPLv2+",
+					"GPLv3+",
+				},
+			},
+			want: "GPL-2.0 AND GPL-3.0",
+		},
+		{
+			name: "happy path with OR operator",
+			input: ftypes.Package{
+				Licenses: []string{
+					"GPLv2+",
+					"LGPL 2.0 or GNU LESSER",
+				},
+			},
+			want: "GPL-2.0 AND ( LGPL-2.0 OR LGPL-3.0 )",
+		},
+		{
+			name: "happy path with AND operator",
+			input: ftypes.Package{
+				Licenses: []string{
+					"GPLv2+",
+					"LGPL 2.0 and GNU LESSER",
+				},
+			},
+			want: "GPL-2.0 AND LGPL-2.0 AND LGPL-3.0",
+		},
+		{
+			name: "happy path with WITH operator",
+			input: ftypes.Package{
+				Licenses: []string{
+					"AFL 2.0",
+					"AFL 3.0 with distribution exception",
+				},
+			},
+			want: "AFL-2.0 AND AFL-3.0 WITH distribution-exception",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equalf(t, tt.want, tspdx.GetLicense(tt.input), "getLicense(%v)", tt.input)
+		})
+	}
+}