From d48c2721b6b94a7aae470dcfcdc0578c971dc556 Mon Sep 17 00:00:00 2001 From: Luca Boccassi Date: Thu, 18 Nov 2021 00:03:48 +0000 Subject: [PATCH] elf-util: add function to parse metadata out of ELF objects Parse the packaging metadata from an ELF object, if any, and print a pretty table following the spec defined at: https://systemd.io/COREDUMP_PACKAGE_METADATA/ --- meson.build | 4 ++ src/shared/elf-util.c | 141 ++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 140 insertions(+), 5 deletions(-) diff --git a/meson.build b/meson.build index c80750c3b59..10efa4bc31a 100644 --- a/meson.build +++ b/meson.build @@ -1329,6 +1329,10 @@ if want_elfutils != 'false' and not skip_deps libdw = dependency('libdw', required : want_elfutils == 'true') have = libdw.found() + + # New in elfutils 0.177 + conf.set10('HAVE_DWELF_ELF_E_MACHINE_STRING', + have and cc.has_function('dwelf_elf_e_machine_string', dependencies : libdw)) else have = false libdw = [] diff --git a/src/shared/elf-util.c b/src/shared/elf-util.c index e5fb8cb2e3f..256744ce955 100644 --- a/src/shared/elf-util.c +++ b/src/shared/elf-util.c @@ -40,6 +40,9 @@ const char *(*sym_dwarf_formstring)(Dwarf_Attribute *); int (*sym_dwarf_getscopes)(Dwarf_Die *, Dwarf_Addr, Dwarf_Die **); int (*sym_dwarf_getscopes_die)(Dwarf_Die *, Dwarf_Die **); Elf *(*sym_dwelf_elf_begin)(int); +#if HAVE_DWELF_ELF_E_MACHINE_STRING +const char *(*sym_dwelf_elf_e_machine_string)(int); +#endif ssize_t (*sym_dwelf_elf_gnu_build_id)(Elf *, const void **); int (*sym_dwarf_tag)(Dwarf_Die *); Dwfl_Module *(*sym_dwfl_addrmodule)(Dwfl *, Dwarf_Addr); @@ -90,6 +93,9 @@ static int dlopen_dw(void) { DLSYM_ARG(dwarf_diename), DLSYM_ARG(dwelf_elf_gnu_build_id), DLSYM_ARG(dwelf_elf_begin), +#if HAVE_DWELF_ELF_E_MACHINE_STRING + DLSYM_ARG(dwelf_elf_e_machine_string), +#endif DLSYM_ARG(dwfl_addrmodule), DLSYM_ARG(dwfl_frame_pc), DLSYM_ARG(dwfl_module_addrdie), @@ -260,7 +266,8 @@ static int thread_callback(Dwfl_Thread *thread, void *userdata) { return DWARF_CB_OK; } -static int parse_package_metadata(const char *name, JsonVariant *id_json, Elf *elf, StackContext *c) { +static int parse_package_metadata(const char *name, JsonVariant *id_json, Elf *elf, bool *ret_interpreter_found, StackContext *c) { + bool interpreter_found = false; size_t n_program_headers; int r; @@ -286,9 +293,14 @@ static int parse_package_metadata(const char *name, JsonVariant *id_json, Elf *e /* Package metadata is in PT_NOTE headers. */ program_header = sym_gelf_getphdr(elf, i, &mem); - if (!program_header || program_header->p_type != PT_NOTE) + if (!program_header || (program_header->p_type != PT_NOTE && program_header->p_type != PT_INTERP)) continue; + if (program_header->p_type == PT_INTERP) { + interpreter_found = true; + continue; + } + /* Fortunately there is an iterator we can use to walk over the * elements of a PT_NOTE program header. We are interested in the * note with type. */ @@ -348,11 +360,17 @@ static int parse_package_metadata(const char *name, JsonVariant *id_json, Elf *e if (r < 0) return log_error_errno(r, "set_put_strdup failed: %m"); + if (ret_interpreter_found) + *ret_interpreter_found = interpreter_found; + return 1; } } } + if (ret_interpreter_found) + *ret_interpreter_found = interpreter_found; + /* Didn't find package metadata for this module - that's ok, just go to the next. */ return 0; } @@ -426,7 +444,7 @@ static int module_callback(Dwfl_Module *mod, void **userdata, const char *name, * to the ELF object first. We might be lucky and just get it from elfutils. */ elf = sym_dwfl_module_getelf(mod, &bias); if (elf) { - r = parse_package_metadata(name, id_json, elf, c); + r = parse_package_metadata(name, id_json, elf, NULL, c); if (r < 0) return DWARF_CB_ABORT; if (r > 0) @@ -468,7 +486,7 @@ static int module_callback(Dwfl_Module *mod, void **userdata, const char *name, _cleanup_(sym_elf_endp) Elf *memelf = sym_elf_memory(data->d_buf, data->d_size); if (!memelf) continue; - r = parse_package_metadata(name, id_json, memelf, c); + r = parse_package_metadata(name, id_json, memelf, NULL, c); if (r < 0) return DWARF_CB_ABORT; if (r > 0) @@ -546,6 +564,119 @@ static int parse_core(int fd, const char *executable, char **ret, JsonVariant ** return 0; } +static int parse_elf(int fd, const char *executable, char **ret, JsonVariant **ret_package_metadata) { + _cleanup_(json_variant_unrefp) JsonVariant *package_metadata = NULL, *elf_metadata = NULL; + _cleanup_(set_freep) Set *modules = NULL; + _cleanup_free_ char *buf = NULL; /* buf should be freed last, c.f closed first (via stack_context_destroy) */ + _cleanup_(stack_context_destroy) StackContext c = { + .package_metadata = &package_metadata, + .modules = &modules, + }; + const char *elf_architecture = NULL, *elf_type; + GElf_Ehdr elf_header; + size_t sz = 0; + int r; + + assert(fd >= 0); + + if (lseek(fd, 0, SEEK_SET) == (off_t) -1) + return log_warning_errno(errno, "Failed to seek to beginning of the ELF file: %m"); + + if (ret) { + c.f = open_memstream_unlocked(&buf, &sz); + if (!c.f) + return log_oom(); + } + + sym_elf_version(EV_CURRENT); + + c.elf = sym_elf_begin(fd, ELF_C_READ_MMAP, NULL); + if (!c.elf) + return log_warning_errno(SYNTHETIC_ERRNO(EINVAL), "Could not parse ELF file, elf_begin() failed: %s", sym_elf_errmsg(sym_elf_errno())); + + if (!sym_gelf_getehdr(c.elf, &elf_header)) + return log_warning_errno(SYNTHETIC_ERRNO(EINVAL), "Could not parse ELF file, gelf_getehdr() failed: %s", sym_elf_errmsg(sym_elf_errno())); + + if (elf_header.e_type == ET_CORE) { + _cleanup_free_ char *out = NULL; + + r = parse_core(fd, executable, ret ? &out : NULL, &package_metadata); + if (r < 0) + return log_warning_errno(r, "Failed to inspect core file: %m"); + + if (out) + fprintf(c.f, "%s", out); + + elf_type = "coredump"; + } else { + _cleanup_(json_variant_unrefp) JsonVariant *id_json = NULL; + bool interpreter_found = false; + + r = parse_buildid(NULL, c.elf, executable, &c, &id_json); + if (r < 0) + return log_warning_errno(r, "Failed to parse build-id of ELF file: %m"); + + r = parse_package_metadata(executable, id_json, c.elf, &interpreter_found, &c); + if (r < 0) + return log_warning_errno(r, "Failed to parse package metadata of ELF file: %m"); + + /* If we found a build-id and nothing else, return at least that. */ + if (!package_metadata && id_json) { + r = json_build(&package_metadata, JSON_BUILD_OBJECT(JSON_BUILD_PAIR(executable, JSON_BUILD_VARIANT(id_json)))); + if (r < 0) + return log_warning_errno(r, "Failed to build JSON object: %m"); + } + + if (interpreter_found) + elf_type = "executable"; + else + elf_type = "library"; + } + + /* Note that e_type is always DYN for both executables and libraries, so we can't tell them apart from the header, + * but we will search for the PT_INTERP section when parsing the metadata. */ + r = json_build(&elf_metadata, JSON_BUILD_OBJECT(JSON_BUILD_PAIR("elfType", JSON_BUILD_STRING(elf_type)))); + if (r < 0) + return log_warning_errno(r, "Failed to build JSON object: %m"); + +#if HAVE_DWELF_ELF_E_MACHINE_STRING + elf_architecture = sym_dwelf_elf_e_machine_string(elf_header.e_machine); +#endif + if (elf_architecture) { + _cleanup_(json_variant_unrefp) JsonVariant *json_architecture = NULL; + + r = json_build(&json_architecture, + JSON_BUILD_OBJECT(JSON_BUILD_PAIR("elfArchitecture", JSON_BUILD_STRING(elf_architecture)))); + if (r < 0) + return log_warning_errno(r, "Failed to build JSON object: %m"); + + r = json_variant_merge(&elf_metadata, json_architecture); + if (r < 0) + return log_warning_errno(r, "Failed to merge JSON objects: %m"); + + if (ret) + fprintf(c.f, "ELF object binary architecture: %s\n", elf_architecture); + } + + /* We always at least have the ELF type, so merge that (and possibly the arch). */ + r = json_variant_merge(&elf_metadata, package_metadata); + if (r < 0) + return log_warning_errno(r, "Failed to merge JSON objects: %m"); + + if (ret) { + r = fflush_and_check(c.f); + if (r < 0) + return log_warning_errno(r, "Could not parse ELF file, flushing file buffer failed: %m"); + + c.f = safe_fclose(c.f); + *ret = TAKE_PTR(buf); + } + if (ret_package_metadata) + *ret_package_metadata = TAKE_PTR(elf_metadata); + + return 0; +} + int parse_elf_object(int fd, const char *executable, bool fork_disable_dump, char **ret, JsonVariant **ret_package_metadata) { _cleanup_close_pair_ int error_pipe[2] = { -1, -1 }, return_pipe[2] = { -1, -1 }, json_pipe[2] = { -1, -1 }; _cleanup_(json_variant_unrefp) JsonVariant *package_metadata = NULL; @@ -607,7 +738,7 @@ int parse_elf_object(int fd, const char *executable, bool fork_disable_dump, cha if (fork_disable_dump) prctl(PR_SET_DUMPABLE, 0); - r = parse_core(fd, executable, ret ? &buf : NULL, ret_package_metadata ? &package_metadata : NULL); + r = parse_elf(fd, executable, ret ? &buf : NULL, ret_package_metadata ? &package_metadata : NULL); if (r < 0) goto child_fail;