Stop injecting symbols into host bionic binaries
The host bionic bootstrapping no longer needs an injected symbol. Replace host_bionic_inject with host_bionic_verify that validates the resulting binary, and add it as a validation dependency of the binary. Test: build and run host bionic binary Change-Id: I3e303d2a164b6eef851bdc8075e6ee456c05b0a8
This commit is contained in:
Colin Cross
23
cmd/host_bionic_verify/Android.bp
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23
cmd/host_bionic_verify/Android.bp
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@@ -0,0 +1,23 @@
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// Copyright 2018 Google Inc. All rights reserved.
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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 {
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default_applicable_licenses: ["Android-Apache-2.0"],
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}
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blueprint_go_binary {
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name: "host_bionic_verify",
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srcs: ["host_bionic_verify.go"],
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testSrcs: ["host_bionic_verify_test.go"],
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}
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144
cmd/host_bionic_verify/host_bionic_verify.go
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144
cmd/host_bionic_verify/host_bionic_verify.go
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// Copyright 2018 Google Inc. All rights reserved.
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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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// Verifies a host bionic executable with an embedded linker.
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package main
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import (
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"debug/elf"
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"flag"
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"fmt"
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"io"
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"os"
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)
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func main() {
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var inputFile, linkerFile string
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flag.StringVar(&inputFile, "i", "", "Input file")
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flag.StringVar(&linkerFile, "l", "", "Linker file")
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flag.Parse()
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if inputFile == "" || linkerFile == "" || flag.NArg() != 0 {
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flag.Usage()
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os.Exit(1)
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}
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r, err := os.Open(inputFile)
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if err != nil {
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fmt.Fprintln(os.Stderr, err.Error())
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os.Exit(2)
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}
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defer r.Close()
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linker, err := elf.Open(linkerFile)
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if err != nil {
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fmt.Fprintln(os.Stderr, err.Error())
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os.Exit(4)
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}
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err = checkElf(r, linker)
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if err != nil {
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fmt.Fprintln(os.Stderr, err.Error())
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os.Exit(5)
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}
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}
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// Check the ELF file, and return the address to the _start function
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func checkElf(r io.ReaderAt, linker *elf.File) error {
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file, err := elf.NewFile(r)
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if err != nil {
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return err
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}
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symbols, err := file.Symbols()
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if err != nil {
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return err
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}
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for _, prog := range file.Progs {
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if prog.Type == elf.PT_INTERP {
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return fmt.Errorf("File should not have a PT_INTERP header")
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}
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}
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if dlwrap_start, err := findSymbol(symbols, "__dlwrap__start"); err != nil {
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return err
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} else if dlwrap_start.Value != file.Entry {
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return fmt.Errorf("Expected file entry(0x%x) to point to __dlwrap_start(0x%x)",
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file.Entry, dlwrap_start.Value)
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}
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err = checkLinker(file, linker, symbols)
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if err != nil {
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return fmt.Errorf("Linker executable failed verification against app embedded linker: %s\n"+
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"linker might not be in sync with crtbegin_dynamic.o.",
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err)
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}
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return nil
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}
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func findSymbol(symbols []elf.Symbol, name string) (elf.Symbol, error) {
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for _, sym := range symbols {
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if sym.Name == name {
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return sym, nil
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}
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}
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return elf.Symbol{}, fmt.Errorf("Failed to find symbol %q", name)
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}
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// Check that all of the PT_LOAD segments have been embedded properly
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func checkLinker(file, linker *elf.File, fileSyms []elf.Symbol) error {
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dlwrapLinkerOffset, err := findSymbol(fileSyms, "__dlwrap_linker_offset")
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if err != nil {
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return err
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}
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for i, lprog := range linker.Progs {
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if lprog.Type != elf.PT_LOAD {
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continue
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}
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laddr := lprog.Vaddr + dlwrapLinkerOffset.Value
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found := false
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for _, prog := range file.Progs {
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if prog.Type != elf.PT_LOAD {
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continue
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}
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if laddr < prog.Vaddr || laddr > prog.Vaddr+prog.Memsz {
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continue
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}
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found = true
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if lprog.Flags != prog.Flags {
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return fmt.Errorf("Linker prog %d (0x%x) flags (%s) do not match (%s)",
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i, lprog.Vaddr, lprog.Flags, prog.Flags)
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}
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if laddr+lprog.Memsz > prog.Vaddr+prog.Filesz {
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return fmt.Errorf("Linker prog %d (0x%x) not fully present (0x%x > 0x%x)",
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i, lprog.Vaddr, laddr+lprog.Memsz, prog.Vaddr+prog.Filesz)
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}
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}
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if !found {
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return fmt.Errorf("Linker prog %d (0x%x) not found at offset 0x%x",
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i, lprog.Vaddr, dlwrapLinkerOffset.Value)
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}
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}
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return nil
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}
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146
cmd/host_bionic_verify/host_bionic_verify_test.go
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146
cmd/host_bionic_verify/host_bionic_verify_test.go
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@@ -0,0 +1,146 @@
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// Copyright 2018 Google Inc. All rights reserved.
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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 main
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import (
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"debug/elf"
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"fmt"
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"testing"
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)
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// prog is a shortcut to fill out a elf.Prog structure
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func prog(flags elf.ProgFlag, offset, addr, filesz, memsz uint64) *elf.Prog {
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return &elf.Prog{
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ProgHeader: elf.ProgHeader{
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Type: elf.PT_LOAD,
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Flags: flags,
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Off: offset,
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Vaddr: addr,
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Paddr: addr,
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Filesz: filesz,
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Memsz: memsz,
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},
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}
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}
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// linkerGold returns an example elf.File from a linker binary that was linked
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// with gold.
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func linkerGold() *elf.File {
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return &elf.File{
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Progs: []*elf.Prog{
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prog(elf.PF_R|elf.PF_X, 0, 0, 0xd0fac, 0xd0fac),
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prog(elf.PF_R|elf.PF_W, 0xd1050, 0xd2050, 0x6890, 0xd88c),
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},
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}
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}
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// fileGold returns an example elf binary with a properly embedded linker. The
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// embedded linker was the one returned by linkerGold.
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func fileGold() *elf.File {
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return &elf.File{
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Progs: []*elf.Prog{
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prog(elf.PF_R, 0, 0, 0x2e0, 0x2e0),
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prog(elf.PF_R|elf.PF_X, 0x1000, 0x1000, 0xd0fac, 0xd0fac),
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prog(elf.PF_R|elf.PF_W, 0xd2050, 0xd3050, 0xd88c, 0xd88c),
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prog(elf.PF_R, 0xe0000, 0xe1000, 0x10e4, 0x10e4),
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prog(elf.PF_R|elf.PF_X, 0xe2000, 0xe3000, 0x1360, 0x1360),
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prog(elf.PF_R|elf.PF_W, 0xe4000, 0xe5000, 0x1358, 0x1358),
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},
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}
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}
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// linkerLld returns an example elf.File from a linker binary that was linked
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// with lld.
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func linkerLld() *elf.File {
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return &elf.File{
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Progs: []*elf.Prog{
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prog(elf.PF_R, 0, 0, 0x3c944, 0x3c944),
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prog(elf.PF_R|elf.PF_X, 0x3d000, 0x3d000, 0x946fa, 0x946fa),
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prog(elf.PF_R|elf.PF_W, 0xd2000, 0xd2000, 0x7450, 0xf778),
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},
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}
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}
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// fileGold returns an example elf binary with a properly embedded linker. The
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// embedded linker was the one returned by linkerLld.
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func fileLld() *elf.File {
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return &elf.File{
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Progs: []*elf.Prog{
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prog(elf.PF_R, 0, 0, 0x3d944, 0x3d944),
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prog(elf.PF_R|elf.PF_X, 0x3e000, 0x3e000, 0x946fa, 0x946fa),
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prog(elf.PF_R|elf.PF_W, 0xd3000, 0xd3000, 0xf778, 0xf778),
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prog(elf.PF_R, 0xe3000, 0xe3000, 0x10e4, 0x10e4),
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prog(elf.PF_R|elf.PF_X, 0xe5000, 0xe5000, 0x1360, 0x1360),
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prog(elf.PF_R|elf.PF_W, 0xe7000, 0xe7000, 0x1358, 0x1358),
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},
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}
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}
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// linkerOffset returns the symbol representing the linker offset used by both
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// fileGold and fileLld
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func linkerOffset() []elf.Symbol {
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return []elf.Symbol{
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elf.Symbol{
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Name: "__dlwrap_linker_offset",
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Value: 0x1000,
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},
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}
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}
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func TestCheckLinker(t *testing.T) {
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cases := []struct {
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name string
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err error
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file func() *elf.File
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linker func() *elf.File
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}{
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{
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name: "good gold-linked linker",
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file: fileGold,
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linker: linkerGold,
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},
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{
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name: "good lld-linked linker",
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file: fileLld,
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linker: linkerLld,
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},
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{
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name: "truncated RO section",
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err: fmt.Errorf("Linker prog 0 (0x0) not fully present (0x3d944 > 0x3d943)"),
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file: func() *elf.File {
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f := fileLld()
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f.Progs[0].Filesz -= 1
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f.Progs[0].Memsz -= 1
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return f
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},
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linker: linkerLld,
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},
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}
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for _, tc := range cases {
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t.Run(tc.name, func(t *testing.T) {
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err := checkLinker(tc.file(), tc.linker(), linkerOffset())
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if tc.err == nil {
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if err != nil {
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t.Fatalf("No error expected, but got: %v", err)
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}
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} else if err == nil {
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t.Fatalf("Returned no error, but wanted: %v", tc.err)
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} else if err.Error() != tc.err.Error() {
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t.Fatalf("Different error found:\nwant: %v\n got: %v", tc.err, err)
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}
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})
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}
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}
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