/
target.go
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/
target.go
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// Copyright 2017 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
package prog
import (
"fmt"
"math/rand"
"sort"
"strings"
"sync"
"sync/atomic"
)
// Target describes target OS/arch pair.
type Target struct {
OS string
Arch string
Revision string // unique hash representing revision of the descriptions
PtrSize uint64
PageSize uint64
NumPages uint64
DataOffset uint64
LittleEndian bool
ExecutorUsesShmem bool
Syscalls []*Syscall
Resources []*ResourceDesc
Consts []ConstValue
Flags []FlagDesc
// MakeDataMmap creates calls that mmaps target data memory range.
MakeDataMmap func() []*Call
// Neutralize neutralizes harmful calls by transforming them into non-harmful ones
// (e.g. an ioctl that turns off console output is turned into ioctl that turns on output).
// fixStructure determines whether it's allowed to make structural changes (e.g. add or
// remove arguments). It is helpful e.g. when we do neutralization while iterating over the
// arguments.
Neutralize func(c *Call, fixStructure bool) error
// AnnotateCall annotates a syscall invocation in C reproducers.
// The returned string will be placed inside a comment except for the
// empty string which will omit the comment.
AnnotateCall func(c ExecCall) string
// SpecialTypes allows target to do custom generation/mutation for some struct's and union's.
// Map key is struct/union name for which custom generation/mutation is required.
// Map value is custom generation/mutation function that will be called
// for the corresponding type. g is helper object that allows generate random numbers,
// allocate memory, etc. typ is the struct/union type. old is the old value of the struct/union
// for mutation, or nil for generation. The function returns a new value of the struct/union,
// and optionally any calls that need to be inserted before the arg reference.
SpecialTypes map[string]func(g *Gen, typ Type, dir Dir, old Arg) (Arg, []*Call)
// Resources that play auxiliary role, but widely used throughout all syscalls (e.g. pid/uid).
AuxResources map[string]bool
// Additional special invalid pointer values besides NULL to use.
SpecialPointers []uint64
// Special file name length that can provoke bugs (e.g. PATH_MAX).
SpecialFileLenghts []int
// Filled by prog package:
SyscallMap map[string]*Syscall
ConstMap map[string]uint64
FlagsMap map[string][]string
init sync.Once
initArch func(target *Target)
types []Type
resourceMap map[string]*ResourceDesc
// Maps resource name to a list of calls that can create the resource.
resourceCtors map[string][]ResourceCtor
any anyTypes
// The default ChoiceTable is used only by tests and utilities, so we initialize it lazily.
defaultOnce sync.Once
defaultChoiceTable *ChoiceTable
}
const maxSpecialPointers = 16
var targets = make(map[string]*Target)
func RegisterTarget(target *Target, types []Type, initArch func(target *Target)) {
key := target.OS + "/" + target.Arch
if targets[key] != nil {
panic(fmt.Sprintf("duplicate target %v", key))
}
target.initArch = initArch
target.types = types
targets[key] = target
}
func GetTarget(OS, arch string) (*Target, error) {
if OS == "android" {
OS = "linux"
}
key := OS + "/" + arch
target := targets[key]
if target == nil {
var supported []string
for _, t := range targets {
supported = append(supported, fmt.Sprintf("%v/%v", t.OS, t.Arch))
}
sort.Strings(supported)
return nil, fmt.Errorf("unknown target: %v (supported: %v)", key, supported)
}
target.init.Do(target.lazyInit)
return target, nil
}
func AllTargets() []*Target {
var res []*Target
for _, target := range targets {
target.init.Do(target.lazyInit)
res = append(res, target)
}
sort.Slice(res, func(i, j int) bool {
if res[i].OS != res[j].OS {
return res[i].OS < res[j].OS
}
return res[i].Arch < res[j].Arch
})
return res
}
func (target *Target) lazyInit() {
target.Neutralize = func(c *Call, fixStructure bool) error { return nil }
target.AnnotateCall = func(c ExecCall) string { return "" }
target.initTarget()
target.initArch(target)
// Give these 2 known addresses fixed positions and prepend target-specific ones at the end.
target.SpecialPointers = append([]uint64{
0x0000000000000000, // NULL pointer (keep this first because code uses special index=0 as NULL)
0xffffffffffffffff, // unmapped kernel address (keep second because serialized value will match actual pointer value)
0x9999999999999999, // non-canonical address
}, target.SpecialPointers...)
if len(target.SpecialPointers) > maxSpecialPointers {
panic("too many special pointers")
}
if len(target.SpecialFileLenghts) == 0 {
// Just some common lengths that can be used as PATH_MAX/MAX_NAME.
target.SpecialFileLenghts = []int{256, 512, 4096}
}
for _, ln := range target.SpecialFileLenghts {
if ln <= 0 || ln >= memAllocMaxMem {
panic(fmt.Sprintf("bad special file length %v", ln))
}
}
// These are used only during lazyInit.
target.types = nil
}
func (target *Target) initTarget() {
checkMaxCallID(len(target.Syscalls) - 1)
target.ConstMap = make(map[string]uint64)
for _, c := range target.Consts {
target.ConstMap[c.Name] = c.Value
}
target.resourceMap = restoreLinks(target.Syscalls, target.Resources, target.types)
target.initAnyTypes()
target.SyscallMap = make(map[string]*Syscall)
for i, c := range target.Syscalls {
c.ID = i
target.SyscallMap[c.Name] = c
}
target.FlagsMap = make(map[string][]string)
for _, c := range target.Flags {
target.FlagsMap[c.Name] = c.Values
}
target.populateResourceCtors()
target.resourceCtors = make(map[string][]ResourceCtor)
for _, res := range target.Resources {
target.resourceCtors[res.Name] = target.calcResourceCtors(res, false)
}
}
func (target *Target) GetConst(name string) uint64 {
v, ok := target.ConstMap[name]
if !ok {
panic(fmt.Sprintf("const %v is not defined for %v/%v", name, target.OS, target.Arch))
}
return v
}
func (target *Target) sanitize(c *Call, fix bool) error {
// For now, even though we accept the fix argument, it does not have the full effect.
// It de facto only denies structural changes, e.g. deletions of arguments.
// TODO: rewrite the corresponding sys/*/init.go code.
return target.Neutralize(c, fix)
}
func RestoreLinks(syscalls []*Syscall, resources []*ResourceDesc, types []Type) {
restoreLinks(syscalls, resources, types)
}
var (
typeRefMu sync.Mutex
typeRefs atomic.Value // []Type
)
func restoreLinks(syscalls []*Syscall, resources []*ResourceDesc, types []Type) map[string]*ResourceDesc {
typeRefMu.Lock()
defer typeRefMu.Unlock()
refs := []Type{nil}
if old := typeRefs.Load(); old != nil {
refs = old.([]Type)
}
for _, typ := range types {
typ.setRef(Ref(len(refs)))
refs = append(refs, typ)
}
typeRefs.Store(refs)
resourceMap := make(map[string]*ResourceDesc)
for _, res := range resources {
resourceMap[res.Name] = res
}
ForeachType(syscalls, func(typ Type, ctx *TypeCtx) {
if ref, ok := typ.(Ref); ok {
typ = types[ref]
*ctx.Ptr = typ
}
switch t := typ.(type) {
case *ResourceType:
t.Desc = resourceMap[t.TypeName]
if t.Desc == nil {
panic("no resource desc")
}
}
})
return resourceMap
}
func (target *Target) DefaultChoiceTable() *ChoiceTable {
target.defaultOnce.Do(func() {
target.defaultChoiceTable = target.BuildChoiceTable(nil, nil)
})
return target.defaultChoiceTable
}
func (target *Target) RequiredGlobs() []string {
globs := make(map[string]bool)
ForeachType(target.Syscalls, func(typ Type, ctx *TypeCtx) {
switch a := typ.(type) {
case *BufferType:
if a.Kind == BufferGlob {
for _, glob := range requiredGlobs(a.SubKind) {
globs[glob] = true
}
}
}
})
return stringMapToSlice(globs)
}
func (target *Target) UpdateGlobs(globFiles map[string][]string) {
// TODO: make host.DetectSupportedSyscalls below filter out globs with no values.
// Also make prog package more strict with respect to generation/mutation of globs
// with no values (they still can appear in tests and tools). We probably should
// generate an empty string for these and never mutate.
ForeachType(target.Syscalls, func(typ Type, ctx *TypeCtx) {
switch a := typ.(type) {
case *BufferType:
if a.Kind == BufferGlob {
a.Values = populateGlob(a.SubKind, globFiles)
}
}
})
}
func requiredGlobs(pattern string) []string {
var res []string
for _, tok := range strings.Split(pattern, ":") {
if tok[0] != '-' {
res = append(res, tok)
}
}
return res
}
func populateGlob(pattern string, globFiles map[string][]string) []string {
files := make(map[string]bool)
parts := strings.Split(pattern, ":")
for _, tok := range parts {
if tok[0] != '-' {
for _, file := range globFiles[tok] {
files[file] = true
}
}
}
for _, tok := range parts {
if tok[0] == '-' {
delete(files, tok[1:])
}
}
return stringMapToSlice(files)
}
func stringMapToSlice(m map[string]bool) []string {
var res []string
for k := range m {
res = append(res, k)
}
sort.Strings(res)
return res
}
type Gen struct {
r *randGen
s *state
}
func (g *Gen) Target() *Target {
return g.r.target
}
func (g *Gen) Rand() *rand.Rand {
return g.r.Rand
}
func (g *Gen) NOutOf(n, outOf int) bool {
return g.r.nOutOf(n, outOf)
}
func (g *Gen) Alloc(ptrType Type, dir Dir, data Arg) (Arg, []*Call) {
return g.r.allocAddr(g.s, ptrType, dir, data.Size(), data), nil
}
func (g *Gen) GenerateArg(typ Type, dir Dir, pcalls *[]*Call) Arg {
return g.generateArg(typ, dir, pcalls, false)
}
func (g *Gen) GenerateSpecialArg(typ Type, dir Dir, pcalls *[]*Call) Arg {
return g.generateArg(typ, dir, pcalls, true)
}
func (g *Gen) generateArg(typ Type, dir Dir, pcalls *[]*Call, ignoreSpecial bool) Arg {
arg, calls := g.r.generateArgImpl(g.s, typ, dir, ignoreSpecial)
*pcalls = append(*pcalls, calls...)
g.r.target.assignSizesArray([]Arg{arg}, []Field{{Name: "", Type: arg.Type()}}, nil)
return arg
}
func (g *Gen) MutateArg(arg0 Arg) (calls []*Call) {
updateSizes := true
for stop := false; !stop; stop = g.r.oneOf(3) {
ma := &mutationArgs{target: g.r.target, ignoreSpecial: true}
ForeachSubArg(arg0, ma.collectArg)
if len(ma.args) == 0 {
// TODO(dvyukov): probably need to return this condition
// and updateSizes to caller so that Mutate can act accordingly.
return
}
arg, ctx := ma.chooseArg(g.r.Rand)
newCalls, ok := g.r.target.mutateArg(g.r, g.s, arg, ctx, &updateSizes)
if !ok {
continue
}
calls = append(calls, newCalls...)
}
return calls
}
type Builder struct {
target *Target
ma *memAlloc
p *Prog
}
func MakeProgGen(target *Target) *Builder {
return &Builder{
target: target,
ma: newMemAlloc(target.NumPages * target.PageSize),
p: &Prog{
Target: target,
},
}
}
func (pg *Builder) Append(c *Call) error {
pg.target.assignSizesCall(c)
pg.target.sanitize(c, true)
pg.p.Calls = append(pg.p.Calls, c)
return nil
}
func (pg *Builder) Allocate(size, alignment uint64) uint64 {
return pg.ma.alloc(nil, size, alignment)
}
func (pg *Builder) AllocateVMA(npages uint64) uint64 {
return pg.ma.alloc(nil, npages*pg.target.PageSize, pg.target.PageSize)
}
func (pg *Builder) Finalize() (*Prog, error) {
if err := pg.p.validate(); err != nil {
return nil, err
}
if _, err := pg.p.SerializeForExec(); err != nil {
return nil, err
}
p := pg.p
pg.p = nil
return p, nil
}