| // Copyright 2022 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package govulncheck |
| |
| import ( |
| "fmt" |
| "go/ast" |
| "go/token" |
| "strconv" |
| "strings" |
| |
| "golang.org/x/vuln/internal" |
| "golang.org/x/vuln/vulncheck" |
| ) |
| |
| // updateInitPositions populates non-existing positions of init functions |
| // and their respective calls in callStacks (see #51575). |
| func updateInitPositions(callStacks map[*vulncheck.Vuln][]vulncheck.CallStack, pkgs []*vulncheck.Package) { |
| pMap := pkgMap(pkgs) |
| for _, css := range callStacks { |
| for _, cs := range css { |
| for i, _ := range cs { |
| updateInitPosition(&cs[i], pMap) |
| if i != len(cs)-1 { |
| updateInitCallPosition(&cs[i], cs[i+1], pMap) |
| } |
| } |
| } |
| } |
| } |
| |
| // updateInitCallPosition updates the position of a call to init in a stack frame, if |
| // one already does not exist: |
| // |
| // P1.init -> P2.init: position of call to P2.init is the position of "import P2" |
| // statement in P1 |
| // |
| // P.init -> P.init#d: P.init is an implicit init. We say it calls the explicit |
| // P.init#d at the place of "package P" statement. |
| func updateInitCallPosition(curr *vulncheck.StackEntry, next vulncheck.StackEntry, pkgs map[string]*vulncheck.Package) { |
| call := curr.Call |
| if !isInit(next.Function) || (call.Pos != nil && call.Pos.IsValid()) { |
| // Skip non-init functions and inits whose call site position is available. |
| return |
| } |
| |
| pkg := pkgs[curr.Function.PkgPath] |
| var pos token.Position |
| if curr.Function.Name == "init" && curr.Function.PkgPath == next.Function.PkgPath { |
| // We have implicit P.init calling P.init#d. Set the call position to |
| // be at "package P" statement position. |
| pos = packageStatementPos(pkg) |
| } else { |
| // Choose the beginning of the import statement as the position. |
| pos = importStatementPos(pkg, next.Function.PkgPath) |
| } |
| |
| call.Pos = &pos |
| } |
| |
| func importStatementPos(pkg *vulncheck.Package, importPath string) token.Position { |
| var importSpec *ast.ImportSpec |
| spec: |
| for _, f := range pkg.Syntax { |
| for _, impSpec := range f.Imports { |
| // Import spec paths have quotation marks. |
| impSpecPath, err := strconv.Unquote(impSpec.Path.Value) |
| if err != nil { |
| panic(fmt.Sprintf("import specification: package path has no quotation marks: %v", err)) |
| } |
| if impSpecPath == importPath { |
| importSpec = impSpec |
| break spec |
| } |
| } |
| } |
| |
| if importSpec == nil { |
| // for sanity, in case of a wild call graph imprecision |
| return token.Position{} |
| } |
| |
| // Choose the beginning of the import statement as the position. |
| return pkg.Fset.Position(importSpec.Pos()) |
| } |
| |
| func packageStatementPos(pkg *vulncheck.Package) token.Position { |
| if len(pkg.Syntax) == 0 { |
| return token.Position{} |
| } |
| // Choose beginning of the package statement as the position. Pick |
| // the first file since it is as good as any. |
| return pkg.Fset.Position(pkg.Syntax[0].Package) |
| } |
| |
| // updateInitPosition updates the position of P.init function in a stack frame if one |
| // is not available. The new position is the position of the "package P" statement. |
| func updateInitPosition(se *vulncheck.StackEntry, pkgs map[string]*vulncheck.Package) { |
| fun := se.Function |
| if !isInit(fun) || (fun.Pos != nil && fun.Pos.IsValid()) { |
| // Skip non-init functions and inits whose position is available. |
| return |
| } |
| |
| pos := packageStatementPos(pkgs[fun.PkgPath]) |
| fun.Pos = &pos |
| } |
| |
| func isInit(f *vulncheck.FuncNode) bool { |
| // A source init function, or anonymous functions used in inits, will |
| // be named "init#x" by vulncheck (more precisely, ssa), where x is a |
| // positive integer. Implicit inits are named simply "init". |
| return f.Name == "init" || strings.HasPrefix(f.Name, "init#") |
| } |
| |
| // summarizeCallStack returns a short description of the call stack. |
| // It uses one of two forms, depending on what the lowest function F in topPkgs |
| // calls: |
| // - If it calls a function V from the vulnerable package, then summarizeCallStack |
| // returns "F calls V". |
| // - If it calls a function G in some other package, which eventually calls V, |
| // it returns "F calls G, which eventually calls V". |
| // |
| // If it can't find any of these functions, summarizeCallStack returns the empty string. |
| func summarizeCallStack(cs CallStack, topPkgs map[string]bool, vulnPkg string) string { |
| // Find the lowest function in the top packages. |
| iTop := lowest(cs.Frames, func(e *StackFrame) bool { |
| return topPkgs[e.PkgPath] |
| }) |
| if iTop < 0 { |
| return "" |
| } |
| // Find the highest function in the vulnerable package that is below iTop. |
| iVuln := highest(cs.Frames[iTop+1:], func(e *StackFrame) bool { |
| return e.PkgPath == vulnPkg |
| }) |
| if iVuln < 0 { |
| return "" |
| } |
| iVuln += iTop + 1 // adjust for slice in call to highest. |
| topName := cs.Frames[iTop].Name() |
| topPos := internal.AbsRelShorter(cs.Frames[iTop].Pos()) |
| if topPos != "" { |
| topPos += ": " |
| } |
| vulnName := cs.Frames[iVuln].Name() |
| if iVuln == iTop+1 { |
| return fmt.Sprintf("%s%s calls %s", topPos, topName, vulnName) |
| } |
| return fmt.Sprintf("%s%s calls %s, which eventually calls %s", |
| topPos, topName, cs.Frames[iTop+1].Name(), vulnName) |
| } |
| |
| // uniqueCallStack returns the first unique call stack among css, if any. |
| // Unique means that the call stack does not go through symbols of vg. |
| func uniqueCallStack(v *vulncheck.Vuln, css []vulncheck.CallStack, vg []*vulncheck.Vuln, r *vulncheck.Result) vulncheck.CallStack { |
| vulnFuncs := make(map[*vulncheck.FuncNode]bool) |
| for _, v := range vg { |
| vulnFuncs[r.Calls.Functions[v.CallSink]] = true |
| } |
| |
| vulnFunc := r.Calls.Functions[v.CallSink] |
| callstack: |
| for _, cs := range css { |
| for _, e := range cs { |
| if e.Function != vulnFunc && vulnFuncs[e.Function] { |
| continue callstack |
| } |
| } |
| return cs |
| } |
| return nil |
| } |