157 lines
4.5 KiB
Go
157 lines
4.5 KiB
Go
// Copyright 2020 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package checklocks performs lock analysis to identify and flag unprotected
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// access to annotated fields.
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//
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// For detailed usage refer to README.md in the same directory.
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package checklocks
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import (
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"go/ast"
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"go/token"
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"go/types"
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"golang.org/x/tools/go/analysis"
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"golang.org/x/tools/go/analysis/passes/buildssa"
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"golang.org/x/tools/go/ssa"
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)
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// Analyzer is the main entrypoint.
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var Analyzer = &analysis.Analyzer{
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Name: "checklocks",
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Doc: "checks lock preconditions on functions and fields",
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Run: run,
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Requires: []*analysis.Analyzer{buildssa.Analyzer},
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FactTypes: []analysis.Fact{(*atomicAlignment)(nil), (*lockFieldFacts)(nil), (*lockGuardFacts)(nil), (*lockFunctionFacts)(nil)},
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}
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// passContext is a pass with additional expected failures.
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type passContext struct {
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pass *analysis.Pass
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failures map[positionKey]*failData
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exemptions map[positionKey]struct{}
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forced map[positionKey]struct{}
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functions map[*ssa.Function]struct{}
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}
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// forAllTypes applies the given function over all types.
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func (pc *passContext) forAllTypes(fn func(ts *ast.TypeSpec)) {
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for _, f := range pc.pass.Files {
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for _, decl := range f.Decls {
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d, ok := decl.(*ast.GenDecl)
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if !ok || d.Tok != token.TYPE {
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continue
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}
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for _, gs := range d.Specs {
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fn(gs.(*ast.TypeSpec))
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}
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}
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}
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}
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// forAllFunctions applies the given function over all functions.
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func (pc *passContext) forAllFunctions(fn func(fn *ast.FuncDecl)) {
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for _, f := range pc.pass.Files {
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for _, decl := range f.Decls {
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d, ok := decl.(*ast.FuncDecl)
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if !ok {
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continue
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}
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fn(d)
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}
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}
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}
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// run is the main entrypoint.
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func run(pass *analysis.Pass) (interface{}, error) {
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pc := &passContext{
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pass: pass,
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failures: make(map[positionKey]*failData),
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exemptions: make(map[positionKey]struct{}),
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forced: make(map[positionKey]struct{}),
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functions: make(map[*ssa.Function]struct{}),
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}
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// Find all line failure annotations.
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pc.extractLineFailures()
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// Find all struct declarations and export relevant facts.
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pc.forAllTypes(func(ts *ast.TypeSpec) {
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if ss, ok := ts.Type.(*ast.StructType); ok {
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structType := pc.pass.TypesInfo.TypeOf(ts.Name).Underlying().(*types.Struct)
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pc.exportLockFieldFacts(structType, ss)
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}
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})
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pc.forAllTypes(func(ts *ast.TypeSpec) {
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if ss, ok := ts.Type.(*ast.StructType); ok {
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structType := pc.pass.TypesInfo.TypeOf(ts.Name).Underlying().(*types.Struct)
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pc.exportLockGuardFacts(structType, ss)
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}
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})
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// Check all alignments.
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pc.forAllTypes(func(ts *ast.TypeSpec) {
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typ, ok := pass.TypesInfo.TypeOf(ts.Name).(*types.Named)
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if !ok {
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return
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}
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pc.checkTypeAlignment(pass.Pkg, typ)
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})
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// Find all function declarations and export relevant facts.
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pc.forAllFunctions(func(fn *ast.FuncDecl) {
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pc.exportFunctionFacts(fn)
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})
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// Scan all code looking for invalid accesses.
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state := pass.ResultOf[buildssa.Analyzer].(*buildssa.SSA)
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for _, fn := range state.SrcFuncs {
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// Import function facts generated above.
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//
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// Note that anonymous(closures) functions do not have an
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// object but do show up in the SSA. They can only be invoked
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// by named functions in the package, and they are analyzing
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// inline on every call. Thus we skip the analysis here. They
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// will be hit on calls, or picked up in the pass below.
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if obj := fn.Object(); obj == nil {
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continue
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}
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var lff lockFunctionFacts
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pc.pass.ImportObjectFact(fn.Object(), &lff)
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// Do we ignore this?
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if lff.Ignore {
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continue
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}
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// Check the basic blocks in the function.
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pc.checkFunction(nil, fn, &lff, nil, false /* force */)
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}
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for _, fn := range state.SrcFuncs {
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// Ensure all anonymous functions are hit. They are not
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// permitted to have any lock preconditions.
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if obj := fn.Object(); obj != nil {
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continue
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}
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var nolff lockFunctionFacts
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pc.checkFunction(nil, fn, &nolff, nil, false /* force */)
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}
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// Check for expected failures.
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pc.checkFailures()
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return nil, nil
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}
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