/
utils.go
173 lines (156 loc) · 5.16 KB
/
utils.go
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package vulnentries
import (
"context"
"go/token"
"go/types"
"strings"
"golang.org/x/tools/go/callgraph"
"golang.org/x/tools/go/callgraph/cha"
"golang.org/x/tools/go/callgraph/vta"
"golang.org/x/tools/go/packages"
"golang.org/x/tools/go/ssa/ssautil"
"golang.org/x/tools/go/types/typeutil"
"golang.org/x/tools/go/ssa"
)
// buildSSA creates an ssa representation for pkgs. Returns
// the ssa program encapsulating the packages and top level
// ssa packages corresponding to pkgs.
func buildSSA(pkgs []*packages.Package, fset *token.FileSet) (*ssa.Program, []*ssa.Package) {
// TODO(https://go.dev/issue/57221): what about entry functions that are generics?
prog := ssa.NewProgram(fset, ssa.InstantiateGenerics)
imports := make(map[*packages.Package]*ssa.Package)
var createImports func(map[string]*packages.Package)
createImports = func(pkgs map[string]*packages.Package) {
for _, p := range pkgs {
if _, ok := imports[p]; !ok {
i := prog.CreatePackage(p.Types, p.Syntax, p.TypesInfo, true)
imports[p] = i
createImports(p.Imports)
}
}
}
for _, tp := range pkgs {
createImports(tp.Imports)
}
var ssaPkgs []*ssa.Package
for _, tp := range pkgs {
if sp, ok := imports[tp]; ok {
ssaPkgs = append(ssaPkgs, sp)
} else {
sp := prog.CreatePackage(tp.Types, tp.Syntax, tp.TypesInfo, false)
ssaPkgs = append(ssaPkgs, sp)
}
}
prog.Build()
return prog, ssaPkgs
}
// callGraph builds a call graph of prog based on VTA analysis.
func callGraph(ctx context.Context, prog *ssa.Program, entries []*ssa.Function) (*callgraph.Graph, error) {
entrySlice := make(map[*ssa.Function]bool)
for _, e := range entries {
entrySlice[e] = true
}
if err := ctx.Err(); err != nil { // cancelled?
return nil, err
}
initial := cha.CallGraph(prog)
allFuncs := ssautil.AllFunctions(prog)
fslice := forwardSlice(entrySlice, initial)
// Keep only actually linked functions.
pruneSet(fslice, allFuncs)
if err := ctx.Err(); err != nil { // cancelled?
return nil, err
}
vtaCg := vta.CallGraph(fslice, initial)
// Repeat the process once more, this time using
// the produced VTA call graph as the base graph.
fslice = forwardSlice(entrySlice, vtaCg)
pruneSet(fslice, allFuncs)
if err := ctx.Err(); err != nil { // cancelled?
return nil, err
}
cg := vta.CallGraph(fslice, vtaCg)
cg.DeleteSyntheticNodes()
return cg, nil
}
// dbTypeFormat formats the name of t according how types
// are encoded in vulnerability database:
// - pointer designation * is skipped
// - full path prefix is skipped as well
func dbTypeFormat(t types.Type) string {
switch tt := t.(type) {
case *types.Pointer:
return dbTypeFormat(tt.Elem())
case *types.Named:
return tt.Obj().Name()
default:
return types.TypeString(t, func(p *types.Package) string { return "" })
}
}
// dbFuncName computes a function name consistent with the namings used in vulnerability
// databases. Effectively, a qualified name of a function local to its enclosing package.
// If a receiver is a pointer, this information is not encoded in the resulting name. The
// name of anonymous functions is simply "". The function names are unique subject to the
// enclosing package, but not globally.
//
// Examples:
//
// func (a A) foo (...) {...} -> A.foo
// func foo(...) {...} -> foo
// func (b *B) bar (...) {...} -> B.bar
func dbFuncName(f *ssa.Function) string {
selectBound := func(f *ssa.Function) types.Type {
// If f is a "bound" function introduced by ssa for a given type, return the type.
// When "f" is a "bound" function, it will have 1 free variable of that type within
// the function. This is subject to change when ssa changes.
if len(f.FreeVars) == 1 && strings.HasPrefix(f.Synthetic, "bound ") {
return f.FreeVars[0].Type()
}
return nil
}
selectThunk := func(f *ssa.Function) types.Type {
// If f is a "thunk" function introduced by ssa for a given type, return the type.
// When "f" is a "thunk" function, the first parameter will have that type within
// the function. This is subject to change when ssa changes.
params := f.Signature.Params() // params.Len() == 1 then params != nil.
if strings.HasPrefix(f.Synthetic, "thunk ") && params.Len() >= 1 {
if first := params.At(0); first != nil {
return first.Type()
}
}
return nil
}
var qprefix string
if recv := f.Signature.Recv(); recv != nil {
qprefix = dbTypeFormat(recv.Type())
} else if btype := selectBound(f); btype != nil {
qprefix = dbTypeFormat(btype)
} else if ttype := selectThunk(f); ttype != nil {
qprefix = dbTypeFormat(ttype)
}
if qprefix == "" {
return f.Name()
}
return qprefix + "." + f.Name()
}
// memberFuncs returns functions associated with the `member`:
// 1) `member` itself if `member` is a function
// 2) `member` methods if `member` is a type
// 3) empty list otherwise
func memberFuncs(member ssa.Member, prog *ssa.Program) []*ssa.Function {
switch t := member.(type) {
case *ssa.Type:
methods := typeutil.IntuitiveMethodSet(t.Type(), &prog.MethodSets)
var funcs []*ssa.Function
for _, m := range methods {
if f := prog.MethodValue(m); f != nil {
funcs = append(funcs, f)
}
}
return funcs
case *ssa.Function:
return []*ssa.Function{t}
default:
return nil
}
}