| #!/usr/bin/env python3.8 |
| # Copyright 2020 The Fuchsia Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| """Verify the content of ELF binaries embedded in a package or filesystem. |
| This scripts takes as input a FINI manifest file and on success, will write |
| an empty stamp file. |
| """ |
| |
| # System imports |
| import argparse |
| import os |
| import sys |
| |
| # elfinfo is in //build/images/ while this script is in //build/dist/. |
| sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..', 'images')) |
| import elfinfo |
| |
| from typing import Any, Iterable, List, Set, Dict, Tuple, Optional |
| |
| # The general strategy for checking the ELF binaries within a package is |
| # the following: |
| # |
| # 1) libzircon.so should never appear inside a Fuchsia package, since |
| # it is injected by the kernel into user processes at runtime. Its |
| # presence in a manifest is a build error. |
| # |
| # On the other hand, it will be listed as a dependency for most |
| # binaries, but not necessarily all of them, and should be ignored |
| # when that happens. |
| # |
| # 2) ld.so.1 is the dynamic loader and also serves as the C library, |
| # which means any DT_NEEDED reference to libc.so is automatically |
| # resolved at runtime to ld.so.1 instead. |
| # |
| # It is thus a build error to have libc.so inside a Fuchsia package, |
| # because the dynamic loader will never load these files! |
| # |
| # 3) ELF executables have a PT_INTERP section that will contain 'ld.so.1' |
| # for Fuchsia regular binaries, and '<variant>/ld.so.1' for those built |
| # with an instrumented variant (e.g. 'asan'). The library loader will |
| # search for DT_NEEDED dependencies in '/lib' in the first case, |
| # and '/lib/<variant>' in the second case, so check that these are |
| # properly located there, as well as their own dependencies. |
| # |
| # For now, it is an error to have a different PT_INTERP value, but |
| # this may be relaxed in the future, for example to package Linux |
| # and Android executables to be run inside Fuchsia containers. |
| # |
| # 4) Loadable modules are ELF shared libraries that are loaded at runtime |
| # by binaries (or the Vulkan loader service) through dlopen(), these |
| # can be located anywhere in the package. They may have DT_NEEDED |
| # dependencies which will be looked up at runtime in the loading |
| # executable's own library directory (i.e. '/lib' or '/lib/<variant>'). |
| # |
| # Because our build system is flexible enough to group regular and |
| # instrumented executables in the same package, there is no 100% |
| # fool-proof way to know which executable will load the module. |
| # |
| # Moreover, one package can even contain a standalone module, without |
| # its own dependencies, to be loaded from another package's component |
| # which would provide them at runtime. This can happen for driver |
| # modules for example. |
| # |
| # Due to this, there is no attempt here to verify the dependencies |
| # of modules, since doing so can only be performed with heuristics |
| # that will fail at some point |
| # |
| # 5) Ignore files under data/, meta/ and lib/firmware, as they could be |
| # any ELF binaries for non-Fuchsia systems, or for testing. |
| # |
| # 6) Verify that debug (unstripped) files for binaries are provided |
| # in the build root directory, or toolchain-specific lib directories. |
| # Missing entries just generate a WARNING, but are not an error |
| # because they do happen in practice (e.g. for prebuilt driver |
| # binaries), though are quite rare. |
| # |
| |
| |
| def rewrite_elf_needed(dep: str) -> Optional[str]: |
| """Rewrite a DT_NEEDED dependency name. |
| |
| Args: |
| dep: dependency name as it appears in ELF DT_NEEDED entry (e.g. 'libc.so') |
| Returns: |
| None if the dependency should be ignored, or the input dependency name, |
| possibly rewritten for specific cases (e.g. 'libc.so' -> 'ld.so.1') |
| """ |
| if dep == 'libzircon.so': |
| # libzircon.so being injected by the kernel into user processes, it should |
| # not appear in Fuchsia packages, and thus should be ignored. |
| return None |
| if dep == 'libc.so': |
| # ld.so.1 acts as both the dynamic loader and C library, so any reference |
| # to libc.so should be rewritten as 'ld.so.1' |
| return 'ld.so.1' |
| |
| # For all other cases, just return the unmodified dependency name. |
| return dep |
| |
| |
| def verify_elf_dependencies( |
| binary: str, lib_dir: str, deps: Iterable[str], |
| elf_entries: Dict[str, Any]) -> Tuple[List[str], List[str]]: |
| """Verify the ELF dependencies of a given ELF binary. |
| |
| Args: |
| binary: Name of the binary whose dependencies are verified. |
| lib_dir: The target directory where all dependencies should be. |
| deps: An iteration of dependency names, as they appear in DT_NEEDED |
| entries. |
| elf_entries: The global {target_path: elf_info} map. |
| Returns: |
| An (errors, libraries) tuple, where 'errors' is a list of error messages |
| in case of failure, or an empty list on succcess, and 'libraries' is a |
| list of libraries that were checked by this function. |
| """ |
| # Note that we do allow circular dependencies because they do happen |
| # in practice. In particular when generating instrumented binaries, |
| # e.g. for the 'asan' case (omitting libzircon.so): |
| # |
| # libc.so (a.k.a. ld.so.1) |
| # ^ ^ ^ | |
| # | | | v |
| # | | libclang_rt.asan.so |
| # | | | ^ ^ |
| # | | v | | |
| # | libc++abi.so | |
| # | | | |
| # | v | |
| # libunwind.so-----------' |
| # |
| errors = [] |
| libraries = [] |
| visited = set() |
| queue = list(deps) |
| while len(queue) > 0: |
| dep = queue[0] |
| queue = queue[1:] |
| dep2 = rewrite_elf_needed(dep) |
| if dep2 is None or dep2 in visited: |
| continue |
| visited.add(dep2) |
| dep_target = os.path.join(lib_dir, dep2) |
| info = elf_entries.get(dep_target) |
| if not info: |
| errors.append('%s missing dependency %s' % (binary, dep_target)) |
| else: |
| libraries.append(dep_target) |
| for subdep in info.needed: |
| if subdep not in visited: |
| queue.append(subdep) |
| |
| return (errors, libraries) |
| |
| |
| def find_debug_file( |
| filename: str, |
| depfile_items: Set[str], |
| toolchain_lib_dirs: List[str] = []) -> Optional[str]: |
| """Find the debug version of a given ELF binary. |
| |
| Args: |
| filename: input file path in build directory. |
| toolchain_lib_dirs: a list of toolchain-specific lib directories |
| which will be used to look for debug/.build-id/xx/xxxxxxx.debug |
| files corresponding to the input files's build-id value. |
| depfile_items: the set of examined files to be updated if needed. |
| |
| Returns |
| Path to the debug file, if it exists, or None. |
| """ |
| if os.path.exists(filename + '.debug'): |
| # Zircon-specific toolchains currently write the debug files |
| # for .../foo as .../foo.debug. |
| debugfile = filename + '.debug' |
| else: |
| # Check for toolchain runtime libraries, which are stored under |
| # {toolchain}/lib/.../libfoo.so, and whose unstripped file will |
| # be under {toolchain}/lib/debug/.build-id/xx/xxxxxx.debug. |
| lib_dir = None |
| for dir in toolchain_lib_dirs: |
| if os.path.realpath(filename).startswith(os.path.realpath(dir) + |
| os.sep): |
| lib_dir = dir |
| break |
| if lib_dir: |
| build_id_dir = os.path.join(lib_dir, 'debug', '.build-id') |
| if not os.path.exists(build_id_dir): |
| return None |
| build_id = elfinfo.get_elf_info(filename).build_id |
| # The build-id value is an hexadecimal string, used to locate the |
| # debug file under debug/.build-id/XX/YYYYYY.debug where XX are its |
| # first two chars, and YYYYYY is the rest (typically longer than |
| # 6 chars). |
| debugfile = os.path.join( |
| build_id_dir, build_id[:2], build_id[2:] + '.debug') |
| if not os.path.exists(debugfile): |
| return None |
| # Pass filename as fallback so we don't fallback to the build-id entry name. |
| return debugfile |
| else: |
| # Otherwise, the Fuchsia build places unstripped files under |
| # .../lib.unstripped/foo.so (for shared library or loadable module |
| # .../foo.so) or .../exe.unstripped/bar (for executable .../bar). |
| dir, file = os.path.split(filename) |
| if file.endswith('.so') or '.so.' in file: |
| subdir = 'lib.unstripped' |
| else: |
| subdir = 'exe.unstripped' |
| debugfile = os.path.join(dir, subdir, file) |
| while not os.path.exists(debugfile): |
| # For dir/foo/bar, if dir/foo/exe.unstripped/bar |
| # didn't exist, try dir/exe.unstripped/foo/bar. |
| parent, dir = os.path.split(dir) |
| if not parent or not dir: |
| return None |
| dir, file = parent, os.path.join(dir, file) |
| debugfile = os.path.join(dir, subdir, file) |
| if not os.path.exists(debugfile): |
| debugfile = os.path.join(subdir, filename) |
| if not os.path.exists(debugfile): |
| return None |
| depfile_items.add(debugfile) |
| return debugfile |
| |
| |
| def main(): |
| parser = argparse.ArgumentParser(description=__doc__) |
| parser.add_argument( |
| '--source-dir', |
| default='.', |
| help='Root directory for source paths. Default is current directory.') |
| parser.add_argument( |
| '--check-stripped', |
| action='store_true', |
| help='Verify that ELF binaries are stripped.') |
| parser.add_argument( |
| '--check-debug-files', |
| action='store_true', |
| help='Verify that each ELF binary has its own debug file available.' + \ |
| 'this requires --toolchain-lib-dir to find toolchain-provided runtime debug files') |
| parser.add_argument( |
| '--toolchain-lib-dir', |
| default=[], |
| action='append', |
| metavar='DIR', |
| help= |
| 'Path to toolchain-provided lib directory. Can be used multiple times.') |
| |
| parser.add_argument( |
| '--manifest', required=True, help='Input FINI manifest.') |
| parser.add_argument('--stamp', required=True, help='Output stamp file.') |
| parser.add_argument('--depfile', help='Output Ninja depfile.') |
| |
| args = parser.parse_args() |
| |
| # Read the input manifest into a {target: source} dictionary. |
| manifest_entries = {} |
| with open(args.manifest) as f: |
| for line in f.readlines(): |
| line = line.rstrip() |
| target, _, source = line.partition('=') |
| assert source is not None, ('Invalid manifest line: [%s]' % line) |
| |
| source_file = os.path.join(args.source_dir, source) |
| |
| # Duplicate entries happen in some manifests, but they will have the |
| # same content, so assert otherwise. |
| if target in manifest_entries: |
| assert manifest_entries[target] == source_file, ( |
| 'Duplicate entries for target "%s": %s vs %s' % |
| (target, source_file, manifest_entries[target])) |
| |
| assert os.path.exists(source_file), ( |
| 'Missing source file for manifest line: %s' % line) |
| manifest_entries[target] = source_file |
| |
| # Filter the input manifest entries to keep only the ELF ones |
| # that are not under data/, lib/firmware/ or meta/ |
| depfile_items = set() |
| elf_entries = {} |
| for target, source_file in manifest_entries.items(): |
| if target.startswith('data/') or target.startswith( |
| 'lib/firmware/') or target.startswith('meta/'): |
| continue |
| |
| depfile_items.add(source_file) |
| info = elfinfo.get_elf_info(source_file) |
| if info is not None: |
| elf_entries[target] = info |
| |
| # errors contains a list of error strings corresponding to issues found in |
| # the input manifest. |
| # |
| # extras contains non-error strings that are useful to dump when an error |
| # occurs, and give more information about what was found in the manifest. |
| # These should only be printed in case of errors, or ignored otherwise. |
| errors = [] |
| extras = [] |
| |
| # The set of all libraries visited when checking dependencies. |
| visited_libraries = set() |
| |
| # Verify that libzircon.so or libc.so do not appear inside the package. |
| for target, info in elf_entries.items(): |
| filename = os.path.basename(target) |
| if filename in ('libzircon.so', 'libc.so'): |
| errors.append( |
| '%s should not be in this package (source=%s)!' % |
| (target, info.filename)) |
| |
| # First verify all executables, since we can find their library directory |
| # from their PT_INTERP value, then check their dependencies recursively. |
| for target, info in elf_entries.items(): |
| interp = info.interp |
| if interp is None: |
| continue |
| |
| interp_name = os.path.basename(interp) |
| if interp_name != 'ld.so.1': |
| errors.append( |
| '%s has invalid or unsupported PT_INTERP value: %s' % |
| (target, interp)) |
| continue |
| |
| lib_dir = os.path.join('lib', os.path.dirname(interp)) |
| extras.append( |
| 'Binary %s has interp %s, lib_dir %s' % (target, interp, lib_dir)) |
| |
| binary_errors, binary_deps = verify_elf_dependencies( |
| target, lib_dir, info.needed, elf_entries) |
| |
| errors += binary_errors |
| visited_libraries.update(binary_deps) |
| |
| # Check that all binaries are stripped if necessary. |
| if args.check_stripped: |
| for target, info in elf_entries.items(): |
| if not info.stripped: |
| errors.append( |
| '%s is not stripped: %s' % (target, info.filename)) |
| |
| # Verify that all ELF files have their debug file available. |
| # This is only a WARNING, not an error, since it can happen for |
| # prebuilt drivers, or with Go binaries. |
| if args.check_debug_files: |
| for target, source_file in manifest_entries.items(): |
| if target in elf_entries: |
| debugfile = find_debug_file( |
| source_file, depfile_items, args.toolchain_lib_dir) |
| if debugfile is None: |
| print('WARNING: No debug file found for %s' % source_file) |
| |
| if errors: |
| print( |
| 'ERRORS FOUND IN %s:\n%s' % (args.manifest, '\n'.join(errors)), |
| file=sys.stderr) |
| if extras: |
| print('\n'.join(extras), file=sys.stderr) |
| return 1 |
| |
| if args.depfile: |
| with open(args.depfile, 'w') as f: |
| f.write( |
| '%s: %s\n' % (args.manifest, ' '.join(sorted(depfile_items)))) |
| |
| # Write the stamp file on success. |
| with open(args.stamp, 'w') as f: |
| f.write('') |
| |
| return 0 |
| |
| |
| if __name__ == "__main__": |
| sys.exit(main()) |
