| // Copyright 2015 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 csource generates [almost] equivalent C programs from syzkaller programs. |
| package csource |
| |
| import ( |
| "bytes" |
| "fmt" |
| "regexp" |
| "sort" |
| "strings" |
| |
| "github.com/google/syzkaller/prog" |
| "github.com/google/syzkaller/sys/targets" |
| ) |
| |
| func Write(p *prog.Prog, opts Options) ([]byte, error) { |
| if err := opts.Check(p.Target.OS); err != nil { |
| return nil, fmt.Errorf("csource: invalid opts: %v", err) |
| } |
| ctx := &context{ |
| p: p, |
| opts: opts, |
| target: p.Target, |
| sysTarget: targets.Get(p.Target.OS, p.Target.Arch), |
| calls: make(map[string]uint64), |
| } |
| |
| calls, vars, err := ctx.generateProgCalls(ctx.p, opts.Trace) |
| if err != nil { |
| return nil, err |
| } |
| |
| mmapProg := p.Target.GenerateUberMmapProg() |
| mmapCalls, _, err := ctx.generateProgCalls(mmapProg, false) |
| if err != nil { |
| return nil, err |
| } |
| |
| for _, c := range append(mmapProg.Calls, p.Calls...) { |
| ctx.calls[c.Meta.CallName] = c.Meta.NR |
| } |
| |
| varsBuf := new(bytes.Buffer) |
| if len(vars) != 0 { |
| fmt.Fprintf(varsBuf, "uint64 r[%v] = {", len(vars)) |
| for i, v := range vars { |
| if i != 0 { |
| fmt.Fprintf(varsBuf, ", ") |
| } |
| fmt.Fprintf(varsBuf, "0x%x", v) |
| } |
| fmt.Fprintf(varsBuf, "};\n") |
| } |
| |
| sandboxFunc := "loop();" |
| if opts.Sandbox != "" { |
| sandboxFunc = "do_sandbox_" + opts.Sandbox + "();" |
| } |
| replacements := map[string]string{ |
| "PROCS": fmt.Sprint(opts.Procs), |
| "REPEAT_TIMES": fmt.Sprint(opts.RepeatTimes), |
| "NUM_CALLS": fmt.Sprint(len(p.Calls)), |
| "MMAP_DATA": strings.Join(mmapCalls, ""), |
| "SYSCALL_DEFINES": ctx.generateSyscallDefines(), |
| "SANDBOX_FUNC": sandboxFunc, |
| "RESULTS": varsBuf.String(), |
| "SYSCALLS": ctx.generateSyscalls(calls, len(vars) != 0), |
| } |
| if !opts.Threaded && !opts.Repeat && opts.Sandbox == "" { |
| // This inlines syscalls right into main for the simplest case. |
| replacements["SANDBOX_FUNC"] = replacements["SYSCALLS"] |
| replacements["SYSCALLS"] = "unused" |
| } |
| // Must match timeouts in executor/executor.cc. |
| specialCallTimeouts := map[string]int{ |
| "syz_usb_connect": 2000, |
| "syz_usb_control_io": 300, |
| "syz_usb_ep_write": 300, |
| "syz_usb_ep_read": 300, |
| "syz_usb_disconnect": 300, |
| } |
| timeoutExpr := "45" |
| for i, call := range p.Calls { |
| if timeout, ok := specialCallTimeouts[call.Meta.CallName]; ok { |
| timeoutExpr += fmt.Sprintf(" + (call == %d ? %d : 0)", i, timeout) |
| } |
| } |
| replacements["CALL_TIMEOUT"] = timeoutExpr |
| result, err := createCommonHeader(p, mmapProg, replacements, opts) |
| if err != nil { |
| return nil, err |
| } |
| const header = "// autogenerated by syzkaller (https://github.com/google/syzkaller)\n\n" |
| result = append([]byte(header), result...) |
| result = ctx.postProcess(result) |
| return result, nil |
| } |
| |
| type context struct { |
| p *prog.Prog |
| opts Options |
| target *prog.Target |
| sysTarget *targets.Target |
| calls map[string]uint64 // CallName -> NR |
| } |
| |
| func (ctx *context) generateSyscalls(calls []string, hasVars bool) string { |
| opts := ctx.opts |
| buf := new(bytes.Buffer) |
| if !opts.Threaded && !opts.Collide { |
| if hasVars || opts.Trace { |
| fmt.Fprintf(buf, "\tintptr_t res = 0;\n") |
| } |
| if opts.Repro { |
| fmt.Fprintf(buf, "\tif (write(1, \"executing program\\n\", sizeof(\"executing program\\n\") - 1)) {}\n") |
| } |
| if opts.Trace { |
| fmt.Fprintf(buf, "\tfprintf(stderr, \"### start\\n\");\n") |
| } |
| for _, c := range calls { |
| fmt.Fprintf(buf, "%s", c) |
| } |
| } else { |
| if hasVars || opts.Trace { |
| fmt.Fprintf(buf, "\tintptr_t res;") |
| } |
| fmt.Fprintf(buf, "\tswitch (call) {\n") |
| for i, c := range calls { |
| fmt.Fprintf(buf, "\tcase %v:\n", i) |
| fmt.Fprintf(buf, "%s", strings.Replace(c, "\t", "\t\t", -1)) |
| fmt.Fprintf(buf, "\t\tbreak;\n") |
| } |
| fmt.Fprintf(buf, "\t}\n") |
| } |
| return buf.String() |
| } |
| |
| func (ctx *context) generateSyscallDefines() string { |
| var calls []string |
| for name, nr := range ctx.calls { |
| if !ctx.sysTarget.SyscallNumbers || |
| strings.HasPrefix(name, "syz_") || !ctx.sysTarget.NeedSyscallDefine(nr) { |
| continue |
| } |
| calls = append(calls, name) |
| } |
| sort.Strings(calls) |
| buf := new(bytes.Buffer) |
| prefix := ctx.sysTarget.SyscallPrefix |
| for _, name := range calls { |
| fmt.Fprintf(buf, "#ifndef %v%v\n", prefix, name) |
| fmt.Fprintf(buf, "#define %v%v %v\n", prefix, name, ctx.calls[name]) |
| fmt.Fprintf(buf, "#endif\n") |
| } |
| if ctx.target.OS == "linux" && ctx.target.PtrSize == 4 { |
| // This is a dirty hack. |
| // On 32-bit linux mmap translated to old_mmap syscall which has a different signature. |
| // mmap2 has the right signature. syz-extract translates mmap to mmap2, do the same here. |
| fmt.Fprintf(buf, "#undef __NR_mmap\n") |
| fmt.Fprintf(buf, "#define __NR_mmap __NR_mmap2\n") |
| } |
| return buf.String() |
| } |
| |
| func (ctx *context) generateProgCalls(p *prog.Prog, trace bool) ([]string, []uint64, error) { |
| exec := make([]byte, prog.ExecBufferSize) |
| progSize, err := p.SerializeForExec(exec) |
| if err != nil { |
| return nil, nil, fmt.Errorf("failed to serialize program: %v", err) |
| } |
| decoded, err := ctx.target.DeserializeExec(exec[:progSize]) |
| if err != nil { |
| return nil, nil, err |
| } |
| calls, vars := ctx.generateCalls(decoded, trace) |
| return calls, vars, nil |
| } |
| |
| func (ctx *context) generateCalls(p prog.ExecProg, trace bool) ([]string, []uint64) { |
| var calls []string |
| csumSeq := 0 |
| for ci, call := range p.Calls { |
| w := new(bytes.Buffer) |
| // Copyin. |
| for _, copyin := range call.Copyin { |
| ctx.copyin(w, &csumSeq, copyin) |
| } |
| |
| if ctx.opts.Fault && ctx.opts.FaultCall == ci { |
| fmt.Fprintf(w, "\tinject_fault(%v);\n", ctx.opts.FaultNth) |
| } |
| // Call itself. |
| callName := call.Meta.CallName |
| resCopyout := call.Index != prog.ExecNoCopyout |
| argCopyout := len(call.Copyout) != 0 |
| emitCall := ctx.opts.EnableTun || |
| callName != "syz_emit_ethernet" && |
| callName != "syz_extract_tcp_res" |
| // TODO: if we don't emit the call we must also not emit copyin, copyout and fault injection. |
| // However, simply skipping whole iteration breaks tests due to unused static functions. |
| if emitCall { |
| ctx.emitCall(w, call, ci, resCopyout || argCopyout, trace) |
| } else if trace { |
| fmt.Fprintf(w, "\t(void)res;\n") |
| } |
| |
| // Copyout. |
| if resCopyout || argCopyout { |
| ctx.copyout(w, call, resCopyout) |
| } |
| calls = append(calls, w.String()) |
| } |
| return calls, p.Vars |
| } |
| |
| func (ctx *context) emitCall(w *bytes.Buffer, call prog.ExecCall, ci int, haveCopyout, trace bool) { |
| callName := call.Meta.CallName |
| native := ctx.sysTarget.SyscallNumbers && !strings.HasPrefix(callName, "syz_") |
| fmt.Fprintf(w, "\t") |
| if haveCopyout || trace { |
| fmt.Fprintf(w, "res = ") |
| } |
| ctx.emitCallName(w, call, native) |
| for ai, arg := range call.Args { |
| if native || ai > 0 { |
| fmt.Fprintf(w, ", ") |
| } |
| switch arg := arg.(type) { |
| case prog.ExecArgConst: |
| if arg.Format != prog.FormatNative && arg.Format != prog.FormatBigEndian { |
| panic("sring format in syscall argument") |
| } |
| fmt.Fprintf(w, "%v", ctx.constArgToStr(arg, true)) |
| case prog.ExecArgResult: |
| if arg.Format != prog.FormatNative && arg.Format != prog.FormatBigEndian { |
| panic("sring format in syscall argument") |
| } |
| val := ctx.resultArgToStr(arg) |
| if native && ctx.target.PtrSize == 4 { |
| // syscall accepts args as ellipsis, resources are uint64 |
| // and take 2 slots without the cast, which would be wrong. |
| val = "(intptr_t)" + val |
| } |
| fmt.Fprintf(w, "%v", val) |
| default: |
| panic(fmt.Sprintf("unknown arg type: %+v", arg)) |
| } |
| } |
| for i := 0; i < call.Meta.MissingArgs; i++ { |
| if native || len(call.Args) != 0 { |
| fmt.Fprintf(w, ", ") |
| } |
| fmt.Fprintf(w, "0") |
| } |
| fmt.Fprintf(w, ");") |
| comment := ctx.target.AnnotateCall(call) |
| if len(comment) != 0 { |
| fmt.Fprintf(w, " /* %s */", comment) |
| } |
| fmt.Fprintf(w, "\n") |
| if trace { |
| cast := "" |
| if !native && !strings.HasPrefix(callName, "syz_") { |
| // Potentially we casted a function returning int to a function returning intptr_t. |
| // So instead of intptr_t -1 we can get 0x00000000ffffffff. Sign extend it to intptr_t. |
| cast = "(intptr_t)(int)" |
| } |
| fmt.Fprintf(w, "\tfprintf(stderr, \"### call=%v errno=%%u\\n\", %vres == -1 ? errno : 0);\n", ci, cast) |
| } |
| } |
| |
| func (ctx *context) emitCallName(w *bytes.Buffer, call prog.ExecCall, native bool) { |
| callName := call.Meta.CallName |
| if native { |
| fmt.Fprintf(w, "syscall(%v%v", ctx.sysTarget.SyscallPrefix, callName) |
| } else if strings.HasPrefix(callName, "syz_") { |
| fmt.Fprintf(w, "%v(", callName) |
| } else { |
| args := strings.Repeat(",intptr_t", len(call.Args)) |
| if args != "" { |
| args = args[1:] |
| } |
| fmt.Fprintf(w, "((intptr_t(*)(%v))CAST(%v))(", args, callName) |
| } |
| } |
| |
| func (ctx *context) generateCsumInet(w *bytes.Buffer, addr uint64, arg prog.ExecArgCsum, csumSeq int) { |
| fmt.Fprintf(w, "\tstruct csum_inet csum_%d;\n", csumSeq) |
| fmt.Fprintf(w, "\tcsum_inet_init(&csum_%d);\n", csumSeq) |
| for i, chunk := range arg.Chunks { |
| switch chunk.Kind { |
| case prog.ExecArgCsumChunkData: |
| fmt.Fprintf(w, "\tNONFAILING(csum_inet_update(&csum_%d, (const uint8*)0x%x, %d));\n", |
| csumSeq, chunk.Value, chunk.Size) |
| case prog.ExecArgCsumChunkConst: |
| fmt.Fprintf(w, "\tuint%d csum_%d_chunk_%d = 0x%x;\n", |
| chunk.Size*8, csumSeq, i, chunk.Value) |
| fmt.Fprintf(w, "\tcsum_inet_update(&csum_%d, (const uint8*)&csum_%d_chunk_%d, %d);\n", |
| csumSeq, csumSeq, i, chunk.Size) |
| default: |
| panic(fmt.Sprintf("unknown checksum chunk kind %v", chunk.Kind)) |
| } |
| } |
| fmt.Fprintf(w, "\tNONFAILING(*(uint16*)0x%x = csum_inet_digest(&csum_%d));\n", |
| addr, csumSeq) |
| } |
| |
| func (ctx *context) copyin(w *bytes.Buffer, csumSeq *int, copyin prog.ExecCopyin) { |
| switch arg := copyin.Arg.(type) { |
| case prog.ExecArgConst: |
| if arg.BitfieldOffset == 0 && arg.BitfieldLength == 0 { |
| ctx.copyinVal(w, copyin.Addr, arg.Size, ctx.constArgToStr(arg, true), arg.Format) |
| } else { |
| if arg.Format != prog.FormatNative && arg.Format != prog.FormatBigEndian { |
| panic("bitfield+string format") |
| } |
| htobe := "" |
| if arg.Format == prog.FormatBigEndian { |
| htobe = fmt.Sprintf("htobe%v", arg.Size*8) |
| } |
| fmt.Fprintf(w, "\tNONFAILING(STORE_BY_BITMASK(uint%v, %v, 0x%x, %v, %v, %v));\n", |
| arg.Size*8, htobe, copyin.Addr, ctx.constArgToStr(arg, false), |
| arg.BitfieldOffset, arg.BitfieldLength) |
| } |
| case prog.ExecArgResult: |
| ctx.copyinVal(w, copyin.Addr, arg.Size, ctx.resultArgToStr(arg), arg.Format) |
| case prog.ExecArgData: |
| fmt.Fprintf(w, "\tNONFAILING(memcpy((void*)0x%x, \"%s\", %v));\n", |
| copyin.Addr, toCString(arg.Data, arg.Readable), len(arg.Data)) |
| case prog.ExecArgCsum: |
| switch arg.Kind { |
| case prog.ExecArgCsumInet: |
| *csumSeq++ |
| ctx.generateCsumInet(w, copyin.Addr, arg, *csumSeq) |
| default: |
| panic(fmt.Sprintf("unknown csum kind %v", arg.Kind)) |
| } |
| default: |
| panic(fmt.Sprintf("bad argument type: %+v", arg)) |
| } |
| } |
| |
| func (ctx *context) copyinVal(w *bytes.Buffer, addr, size uint64, val string, bf prog.BinaryFormat) { |
| switch bf { |
| case prog.FormatNative, prog.FormatBigEndian: |
| fmt.Fprintf(w, "\tNONFAILING(*(uint%v*)0x%x = %v);\n", size*8, addr, val) |
| case prog.FormatStrDec: |
| if size != 20 { |
| panic("bad strdec size") |
| } |
| fmt.Fprintf(w, "\tNONFAILING(sprintf((char*)0x%x, \"%%020llu\", (long long)%v));\n", addr, val) |
| case prog.FormatStrHex: |
| if size != 18 { |
| panic("bad strdec size") |
| } |
| fmt.Fprintf(w, "\tNONFAILING(sprintf((char*)0x%x, \"0x%%016llx\", (long long)%v));\n", addr, val) |
| case prog.FormatStrOct: |
| if size != 23 { |
| panic("bad strdec size") |
| } |
| fmt.Fprintf(w, "\tNONFAILING(sprintf((char*)0x%x, \"%%023llo\", (long long)%v));\n", addr, val) |
| default: |
| panic("unknown binary format") |
| } |
| } |
| |
| func (ctx *context) copyout(w *bytes.Buffer, call prog.ExecCall, resCopyout bool) { |
| if ctx.sysTarget.OS == "fuchsia" { |
| // On fuchsia we have real system calls that return ZX_OK on success, |
| // and libc calls that are casted to function returning intptr_t, |
| // as the result int -1 is returned as 0x00000000ffffffff rather than full -1. |
| if strings.HasPrefix(call.Meta.CallName, "zx_") { |
| fmt.Fprintf(w, "\tif (res == ZX_OK)") |
| } else { |
| fmt.Fprintf(w, "\tif ((int)res != -1)") |
| } |
| } else { |
| fmt.Fprintf(w, "\tif (res != -1)") |
| } |
| copyoutMultiple := len(call.Copyout) > 1 || resCopyout && len(call.Copyout) > 0 |
| if copyoutMultiple { |
| fmt.Fprintf(w, " {") |
| } |
| fmt.Fprintf(w, "\n") |
| if resCopyout { |
| fmt.Fprintf(w, "\t\tr[%v] = res;\n", call.Index) |
| } |
| for _, copyout := range call.Copyout { |
| fmt.Fprintf(w, "\t\tNONFAILING(r[%v] = *(uint%v*)0x%x);\n", |
| copyout.Index, copyout.Size*8, copyout.Addr) |
| } |
| if copyoutMultiple { |
| fmt.Fprintf(w, "\t}\n") |
| } |
| } |
| |
| func (ctx *context) constArgToStr(arg prog.ExecArgConst, handleBigEndian bool) string { |
| mask := (uint64(1) << (arg.Size * 8)) - 1 |
| v := arg.Value & mask |
| val := fmt.Sprintf("%v", v) |
| if v == ^uint64(0)&mask { |
| val = "-1" |
| } else if v >= 10 { |
| val = fmt.Sprintf("0x%x", v) |
| } |
| if ctx.opts.Procs > 1 && arg.PidStride != 0 { |
| val += fmt.Sprintf(" + procid*%v", arg.PidStride) |
| } |
| if handleBigEndian && arg.Format == prog.FormatBigEndian { |
| val = fmt.Sprintf("htobe%v(%v)", arg.Size*8, val) |
| } |
| return val |
| } |
| |
| func (ctx *context) resultArgToStr(arg prog.ExecArgResult) string { |
| res := fmt.Sprintf("r[%v]", arg.Index) |
| if arg.DivOp != 0 { |
| res = fmt.Sprintf("%v/%v", res, arg.DivOp) |
| } |
| if arg.AddOp != 0 { |
| res = fmt.Sprintf("%v+%v", res, arg.AddOp) |
| } |
| if arg.Format == prog.FormatBigEndian { |
| res = fmt.Sprintf("htobe%v(%v)", arg.Size*8, res) |
| } |
| return res |
| } |
| |
| func (ctx *context) postProcess(result []byte) []byte { |
| // Remove NONFAILING, debug, fail, etc calls. |
| if !ctx.opts.HandleSegv { |
| result = regexp.MustCompile(`\t*NONFAILING\((.*)\);\n`).ReplaceAll(result, []byte("$1;\n")) |
| } |
| result = bytes.Replace(result, []byte("NORETURN"), nil, -1) |
| result = bytes.Replace(result, []byte("doexit("), []byte("exit("), -1) |
| result = regexp.MustCompile(`PRINTF\(.*?\)`).ReplaceAll(result, nil) |
| result = regexp.MustCompile(`\t*debug\((.*\n)*?.*\);\n`).ReplaceAll(result, nil) |
| result = regexp.MustCompile(`\t*debug_dump_data\((.*\n)*?.*\);\n`).ReplaceAll(result, nil) |
| result = regexp.MustCompile(`\t*exitf\((.*\n)*?.*\);\n`).ReplaceAll(result, []byte("\texit(1);\n")) |
| result = regexp.MustCompile(`\t*fail\((.*\n)*?.*\);\n`).ReplaceAll(result, []byte("\texit(1);\n")) |
| |
| result = ctx.hoistIncludes(result) |
| result = ctx.removeEmptyLines(result) |
| return result |
| } |
| |
| // hoistIncludes moves all includes to the top, removes dups and sorts. |
| func (ctx *context) hoistIncludes(result []byte) []byte { |
| includesStart := bytes.Index(result, []byte("#include")) |
| if includesStart == -1 { |
| return result |
| } |
| includes := make(map[string]bool) |
| includeRe := regexp.MustCompile("#include <.*>\n") |
| for _, match := range includeRe.FindAll(result, -1) { |
| includes[string(match)] = true |
| } |
| result = includeRe.ReplaceAll(result, nil) |
| // Certain linux and bsd headers are broken and go to the bottom. |
| var sorted, sortedBottom, sortedTop []string |
| for include := range includes { |
| if strings.Contains(include, "<linux/") { |
| sortedBottom = append(sortedBottom, include) |
| } else if strings.Contains(include, "<netinet/if_ether.h>") { |
| sortedBottom = append(sortedBottom, include) |
| } else if ctx.target.OS == freebsd && strings.Contains(include, "<sys/types.h>") { |
| sortedTop = append(sortedTop, include) |
| } else { |
| sorted = append(sorted, include) |
| } |
| } |
| sort.Strings(sortedTop) |
| sort.Strings(sorted) |
| sort.Strings(sortedBottom) |
| newResult := append([]byte{}, result[:includesStart]...) |
| newResult = append(newResult, strings.Join(sortedTop, "")...) |
| newResult = append(newResult, '\n') |
| newResult = append(newResult, strings.Join(sorted, "")...) |
| newResult = append(newResult, '\n') |
| newResult = append(newResult, strings.Join(sortedBottom, "")...) |
| newResult = append(newResult, result[includesStart:]...) |
| return newResult |
| } |
| |
| // removeEmptyLines removes duplicate new lines. |
| func (ctx *context) removeEmptyLines(result []byte) []byte { |
| for { |
| newResult := bytes.Replace(result, []byte{'\n', '\n', '\n'}, []byte{'\n', '\n'}, -1) |
| newResult = bytes.Replace(newResult, []byte{'\n', '\n', '\t'}, []byte{'\n', '\t'}, -1) |
| newResult = bytes.Replace(newResult, []byte{'\n', '\n', ' '}, []byte{'\n', ' '}, -1) |
| if len(newResult) == len(result) { |
| return result |
| } |
| result = newResult |
| } |
| } |
| |
| func toCString(data []byte, readable bool) []byte { |
| if len(data) == 0 { |
| panic("empty data arg") |
| } |
| buf := new(bytes.Buffer) |
| prog.EncodeData(buf, data, readable) |
| return buf.Bytes() |
| } |
