410 lines
12 KiB
Go
410 lines
12 KiB
Go
// Copyright 2023 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package sarif
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import (
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"encoding/json"
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"fmt"
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"io"
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"path/filepath"
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"sort"
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"golang.org/x/vuln/internal"
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"golang.org/x/vuln/internal/govulncheck"
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"golang.org/x/vuln/internal/osv"
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"golang.org/x/vuln/internal/traces"
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)
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// handler for sarif output.
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type handler struct {
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w io.Writer
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cfg *govulncheck.Config
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osvs map[string]*osv.Entry
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// findings contains same-level findings for an
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// OSV at the most precise level of granularity
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// available. This means, for instance, that if
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// an osv is indeed called, then all findings for
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// the osv will have call stack info.
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findings map[string][]*govulncheck.Finding
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}
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func NewHandler(w io.Writer) *handler {
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return &handler{
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w: w,
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osvs: make(map[string]*osv.Entry),
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findings: make(map[string][]*govulncheck.Finding),
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}
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}
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func (h *handler) Config(c *govulncheck.Config) error {
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h.cfg = c
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return nil
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}
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func (h *handler) Progress(p *govulncheck.Progress) error {
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return nil // not needed by sarif
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}
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func (h *handler) SBOM(s *govulncheck.SBOM) error {
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return nil // not needed by sarif
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}
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func (h *handler) OSV(e *osv.Entry) error {
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h.osvs[e.ID] = e
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return nil
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}
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// moreSpecific favors a call finding over a non-call
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// finding and a package finding over a module finding.
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func moreSpecific(f1, f2 *govulncheck.Finding) int {
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if len(f1.Trace) > 1 && len(f2.Trace) > 1 {
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// Both are call stack findings.
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return 0
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}
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if len(f1.Trace) > 1 {
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return -1
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}
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if len(f2.Trace) > 1 {
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return 1
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}
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fr1, fr2 := f1.Trace[0], f2.Trace[0]
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if fr1.Function != "" && fr2.Function == "" {
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return -1
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}
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if fr1.Function == "" && fr2.Function != "" {
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return 1
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}
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if fr1.Package != "" && fr2.Package == "" {
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return -1
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}
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if fr1.Package == "" && fr2.Package != "" {
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return -1
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}
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return 0 // findings always have module info
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}
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func (h *handler) Finding(f *govulncheck.Finding) error {
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fs := h.findings[f.OSV]
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if len(fs) == 0 {
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fs = []*govulncheck.Finding{f}
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} else {
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if ms := moreSpecific(f, fs[0]); ms == -1 {
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// The new finding is more specific, so we need
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// to erase existing findings and add the new one.
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fs = []*govulncheck.Finding{f}
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} else if ms == 0 {
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// The new finding is equal to an existing one and
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// because of the invariant on h.findings, it is
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// also equal to all existing ones.
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fs = append(fs, f)
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}
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// Otherwise, the new finding is at a less precise level.
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}
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h.findings[f.OSV] = fs
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return nil
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}
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// Flush is used to print out to w the sarif json output.
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// This is needed as sarif is not streamed.
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func (h *handler) Flush() error {
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sLog := toSarif(h)
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s, err := json.MarshalIndent(sLog, "", " ")
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if err != nil {
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return err
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}
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h.w.Write(s)
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return nil
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}
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func toSarif(h *handler) Log {
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cfg := h.cfg
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r := Run{
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Tool: Tool{
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Driver: Driver{
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Name: cfg.ScannerName,
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Version: cfg.ScannerVersion,
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InformationURI: "https://pkg.go.dev/golang.org/x/vuln/cmd/govulncheck",
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Properties: *cfg,
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Rules: rules(h),
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},
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},
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Results: results(h),
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}
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return Log{
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Version: "2.1.0",
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Schema: "https://json.schemastore.org/sarif-2.1.0.json",
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Runs: []Run{r},
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}
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}
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func rules(h *handler) []Rule {
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rs := make([]Rule, 0, len(h.findings)) // must not be nil
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for id := range h.findings {
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osv := h.osvs[id]
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// s is either summary if it exists, or details
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// otherwise. Govulncheck text does the same.
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s := osv.Summary
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if s == "" {
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s = osv.Details
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}
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rs = append(rs, Rule{
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ID: osv.ID,
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ShortDescription: Description{Text: fmt.Sprintf("[%s] %s", osv.ID, s)},
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FullDescription: Description{Text: s},
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HelpURI: fmt.Sprintf("https://pkg.go.dev/vuln/%s", osv.ID),
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Help: Description{Text: osv.Details},
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Properties: RuleTags{Tags: tags(osv)},
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})
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}
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sort.SliceStable(rs, func(i, j int) bool { return rs[i].ID < rs[j].ID })
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return rs
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}
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// tags returns an slice of zero or
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// more aliases of o.
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func tags(o *osv.Entry) []string {
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if len(o.Aliases) > 0 {
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return o.Aliases
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}
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return []string{} // must not be nil
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}
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func results(h *handler) []Result {
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results := make([]Result, 0, len(h.findings)) // must not be nil
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for osv, fs := range h.findings {
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var locs []Location
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if h.cfg.ScanMode != govulncheck.ScanModeBinary {
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// Attach result to the go.mod file for source analysis.
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// But there is no such place for binaries.
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locs = []Location{{PhysicalLocation: PhysicalLocation{
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ArtifactLocation: ArtifactLocation{
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URI: "go.mod",
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URIBaseID: SrcRootID,
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},
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Region: Region{StartLine: 1}, // for now, point to the first line
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},
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Message: Description{Text: fmt.Sprintf("Findings for vulnerability %s", osv)}, // not having a message here results in an invalid sarif
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}}
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}
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res := Result{
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RuleID: osv,
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Level: level(fs[0], h.cfg),
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Message: Description{Text: resultMessage(fs, h.cfg)},
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Stacks: stacks(h, fs),
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CodeFlows: codeFlows(h, fs),
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Locations: locs,
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}
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results = append(results, res)
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}
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sort.SliceStable(results, func(i, j int) bool { return results[i].RuleID < results[j].RuleID }) // for deterministic output
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return results
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}
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func resultMessage(findings []*govulncheck.Finding, cfg *govulncheck.Config) string {
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// We can infer the findings' level by just looking at the
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// top trace frame of any finding.
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frame := findings[0].Trace[0]
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uniqueElems := make(map[string]bool)
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if frame.Function == "" && frame.Package == "" { // module level findings
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for _, f := range findings {
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uniqueElems[f.Trace[0].Module] = true
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}
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} else { // symbol and package level findings
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for _, f := range findings {
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uniqueElems[f.Trace[0].Package] = true
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}
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}
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var elems []string
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for e := range uniqueElems {
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elems = append(elems, e)
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}
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sort.Strings(elems)
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l := len(elems)
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elemList := list(elems)
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main, addition := "", ""
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const runCallAnalysis = "Run the call-level analysis to understand whether your code actually calls the vulnerabilities."
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switch {
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case frame.Function != "":
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main = fmt.Sprintf("calls vulnerable functions in %d package%s (%s).", l, choose("", "s", l == 1), elemList)
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case frame.Package != "":
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main = fmt.Sprintf("imports %d vulnerable package%s (%s)", l, choose("", "s", l == 1), elemList)
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addition = choose(", but doesn’t appear to call any of the vulnerable symbols.", ". "+runCallAnalysis, cfg.ScanLevel.WantSymbols())
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default:
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main = fmt.Sprintf("depends on %d vulnerable module%s (%s)", l, choose("", "s", l == 1), elemList)
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informational := ", but doesn't appear to " + choose("call", "import", cfg.ScanLevel.WantSymbols()) + " any of the vulnerable symbols."
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addition = choose(informational, ". "+runCallAnalysis, cfg.ScanLevel.WantPackages())
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}
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return fmt.Sprintf("Your code %s%s", main, addition)
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}
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const (
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errorLevel = "error"
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warningLevel = "warning"
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informationalLevel = "note"
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)
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func level(f *govulncheck.Finding, cfg *govulncheck.Config) string {
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fr := f.Trace[0]
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switch {
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case cfg.ScanLevel.WantSymbols():
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if fr.Function != "" {
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return errorLevel
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}
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if fr.Package != "" {
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return warningLevel
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}
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return informationalLevel
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case cfg.ScanLevel.WantPackages():
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if fr.Package != "" {
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return errorLevel
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}
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return warningLevel
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default:
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return errorLevel
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}
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}
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func stacks(h *handler, fs []*govulncheck.Finding) []Stack {
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if fs[0].Trace[0].Function == "" { // not call level findings
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return nil
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}
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var stacks []Stack
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for _, f := range fs {
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stacks = append(stacks, stack(h, f))
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}
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// Sort stacks for deterministic output. We sort by message
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// which is effectively sorting by full symbol name. The
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// performance should not be an issue here.
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sort.SliceStable(stacks, func(i, j int) bool { return stacks[i].Message.Text < stacks[j].Message.Text })
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return stacks
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}
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// stack transforms call stack in f to a sarif stack.
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func stack(h *handler, f *govulncheck.Finding) Stack {
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trace := f.Trace
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top := trace[len(trace)-1] // belongs to top level module
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frames := make([]Frame, 0, len(trace)) // must not be nil
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for i := len(trace) - 1; i >= 0; i-- { // vulnerable symbol is at the top frame
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frame := trace[i]
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pos := govulncheck.Position{Line: 1, Column: 1}
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if frame.Position != nil {
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pos = *frame.Position
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}
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sf := Frame{
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Module: frame.Module + "@" + frame.Version,
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Location: Location{Message: Description{Text: symbol(frame)}}, // show the (full) symbol name
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}
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file, base := fileURIInfo(pos.Filename, top.Module, frame.Module, frame.Version)
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if h.cfg.ScanMode != govulncheck.ScanModeBinary {
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sf.Location.PhysicalLocation = PhysicalLocation{
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ArtifactLocation: ArtifactLocation{
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URI: file,
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URIBaseID: base,
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},
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Region: Region{
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StartLine: pos.Line,
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StartColumn: pos.Column,
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},
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}
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}
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frames = append(frames, sf)
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}
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return Stack{
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Frames: frames,
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Message: Description{Text: fmt.Sprintf("A call stack for vulnerable function %s", symbol(trace[0]))},
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}
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}
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func codeFlows(h *handler, fs []*govulncheck.Finding) []CodeFlow {
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if fs[0].Trace[0].Function == "" { // not call level findings
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return nil
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}
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// group call stacks per symbol. There should
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// be one call stack currently per symbol, but
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// this might change in the future.
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m := make(map[govulncheck.Frame][]*govulncheck.Finding)
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for _, f := range fs {
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// fr.Position is currently the position
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// of the definition of the vuln symbol
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fr := *f.Trace[0]
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m[fr] = append(m[fr], f)
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}
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var codeFlows []CodeFlow
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for fr, fs := range m {
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tfs := threadFlows(h, fs)
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codeFlows = append(codeFlows, CodeFlow{
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ThreadFlows: tfs,
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// TODO: should we instead show the message from govulncheck text output?
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Message: Description{Text: fmt.Sprintf("A summarized code flow for vulnerable function %s", symbol(&fr))},
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})
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}
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// Sort flows for deterministic output. We sort by message
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// which is effectively sorting by full symbol name. The
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// performance should not be an issue here.
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sort.SliceStable(codeFlows, func(i, j int) bool { return codeFlows[i].Message.Text < codeFlows[j].Message.Text })
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return codeFlows
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}
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func threadFlows(h *handler, fs []*govulncheck.Finding) []ThreadFlow {
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tfs := make([]ThreadFlow, 0, len(fs)) // must not be nil
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for _, f := range fs {
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trace := traces.Compact(f)
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top := trace[len(trace)-1] // belongs to top level module
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var tf []ThreadFlowLocation
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for i := len(trace) - 1; i >= 0; i-- { // vulnerable symbol is at the top frame
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// TODO: should we, similar to govulncheck text output, only
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// mention three elements of the compact trace?
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frame := trace[i]
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pos := govulncheck.Position{Line: 1, Column: 1}
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if frame.Position != nil {
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pos = *frame.Position
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}
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tfl := ThreadFlowLocation{
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Module: frame.Module + "@" + frame.Version,
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Location: Location{Message: Description{Text: symbol(frame)}}, // show the (full) symbol name
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}
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file, base := fileURIInfo(pos.Filename, top.Module, frame.Module, frame.Version)
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if h.cfg.ScanMode != govulncheck.ScanModeBinary {
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tfl.Location.PhysicalLocation = PhysicalLocation{
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ArtifactLocation: ArtifactLocation{
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URI: file,
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URIBaseID: base,
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},
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Region: Region{
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StartLine: pos.Line,
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StartColumn: pos.Column,
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},
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}
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}
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tf = append(tf, tfl)
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}
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tfs = append(tfs, ThreadFlow{Locations: tf})
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}
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return tfs
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}
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func fileURIInfo(filename, top, module, version string) (string, string) {
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if top == module {
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return filename, SrcRootID
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}
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if module == internal.GoStdModulePath {
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return filename, GoRootID
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}
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return filepath.ToSlash(filepath.Join(module+"@"+version, filename)), GoModCacheID
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}
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