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systemd/src/shared/elf-util.c
Daan De Meyer 004b7f1f7e elf-util: Add support for parsing dlopen metadata 
Then we can add support for showing dlopen metadata to systemd-analyze.
2025-10-30 08:41:43 +01:00

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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#if HAVE_ELFUTILS
#include <dwarf.h>
#include <elfutils/libdwelf.h>
#include <elfutils/libdwfl.h>
#include <libelf.h>
#endif
#include <unistd.h>
#include "sd-json.h"
#include "alloc-util.h"
#include "coredump-util.h"
#include "dlfcn-util.h"
#include "elf-util.h"
#include "errno-util.h"
#include "escape.h"
#include "fd-util.h"
#include "fileio.h"
#include "format-util.h"
#include "io-util.h"
#include "json-util.h"
#include "log.h"
#include "memstream-util.h"
#include "path-util.h"
#include "process-util.h"
#include "set.h"
#include "string-util.h"
#define FRAMES_MAX 64
#define THREADS_MAX 64
#define ELF_PACKAGE_METADATA_ID 0xcafe1a7e
/* The amount of data we're willing to write to each of the output pipes. */
#define COREDUMP_PIPE_MAX (1024*1024U)
#if HAVE_ELFUTILS
static void *dw_dl = NULL;
static void *elf_dl = NULL;
/* libdw symbols */
static DLSYM_PROTOTYPE(dwarf_attr_integrate) = NULL;
static DLSYM_PROTOTYPE(dwarf_diename) = NULL;
static DLSYM_PROTOTYPE(dwarf_formstring) = NULL;
static DLSYM_PROTOTYPE(dwarf_getscopes) = NULL;
static DLSYM_PROTOTYPE(dwarf_getscopes_die) = NULL;
static DLSYM_PROTOTYPE(dwelf_elf_begin) = NULL;
#if HAVE_DWELF_ELF_E_MACHINE_STRING
static DLSYM_PROTOTYPE(dwelf_elf_e_machine_string) = NULL;
#endif
static DLSYM_PROTOTYPE(dwelf_elf_gnu_build_id) = NULL;
static DLSYM_PROTOTYPE(dwarf_tag) = NULL;
static DLSYM_PROTOTYPE(dwfl_addrmodule) = NULL;
static DLSYM_PROTOTYPE(dwfl_begin) = NULL;
static DLSYM_PROTOTYPE(dwfl_build_id_find_elf) = NULL;
static DLSYM_PROTOTYPE(dwfl_core_file_attach) = NULL;
static DLSYM_PROTOTYPE(dwfl_core_file_report) = NULL;
#if HAVE_DWFL_SET_SYSROOT
static DLSYM_PROTOTYPE(dwfl_set_sysroot) = NULL;
#endif
static DLSYM_PROTOTYPE(dwfl_end) = NULL;
static DLSYM_PROTOTYPE(dwfl_errmsg) = NULL;
static DLSYM_PROTOTYPE(dwfl_errno) = NULL;
static DLSYM_PROTOTYPE(dwfl_frame_pc) = NULL;
static DLSYM_PROTOTYPE(dwfl_getmodules) = NULL;
static DLSYM_PROTOTYPE(dwfl_getthreads) = NULL;
static DLSYM_PROTOTYPE(dwfl_module_addrdie) = NULL;
static DLSYM_PROTOTYPE(dwfl_module_addrname) = NULL;
static DLSYM_PROTOTYPE(dwfl_module_build_id) = NULL;
static DLSYM_PROTOTYPE(dwfl_module_getelf) = NULL;
static DLSYM_PROTOTYPE(dwfl_module_info) = NULL;
static DLSYM_PROTOTYPE(dwfl_offline_section_address) = NULL;
static DLSYM_PROTOTYPE(dwfl_report_end) = NULL;
static DLSYM_PROTOTYPE(dwfl_standard_find_debuginfo) = NULL;
static DLSYM_PROTOTYPE(dwfl_thread_getframes) = NULL;
static DLSYM_PROTOTYPE(dwfl_thread_tid) = NULL;
/* libelf symbols */
static DLSYM_PROTOTYPE(elf_begin) = NULL;
static DLSYM_PROTOTYPE(elf_end) = NULL;
static DLSYM_PROTOTYPE(elf_getdata_rawchunk) = NULL;
static DLSYM_PROTOTYPE(gelf_getehdr) = NULL;
static DLSYM_PROTOTYPE(elf_getphdrnum) = NULL;
static DLSYM_PROTOTYPE(elf_errmsg) = NULL;
static DLSYM_PROTOTYPE(elf_errno) = NULL;
static DLSYM_PROTOTYPE(elf_memory) = NULL;
static DLSYM_PROTOTYPE(elf_version) = NULL;
static DLSYM_PROTOTYPE(gelf_getphdr) = NULL;
static DLSYM_PROTOTYPE(gelf_getnote) = NULL;
#endif
int dlopen_dw(void) {
#if HAVE_ELFUTILS
int r;
ELF_NOTE_DLOPEN("dw",
"Support for backtrace and ELF package metadata decoding from core files",
ELF_NOTE_DLOPEN_PRIORITY_SUGGESTED,
"libdw.so.1");
r = dlopen_many_sym_or_warn(
&dw_dl, "libdw.so.1", LOG_DEBUG,
DLSYM_ARG(dwarf_getscopes),
DLSYM_ARG(dwarf_getscopes_die),
DLSYM_ARG(dwarf_tag),
DLSYM_ARG(dwarf_attr_integrate),
DLSYM_ARG(dwarf_formstring),
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),
DLSYM_ARG(dwfl_module_addrname),
DLSYM_ARG(dwfl_module_info),
DLSYM_ARG(dwfl_module_build_id),
DLSYM_ARG(dwfl_module_getelf),
DLSYM_ARG(dwfl_begin),
DLSYM_ARG(dwfl_core_file_report),
#if HAVE_DWFL_SET_SYSROOT
DLSYM_ARG(dwfl_set_sysroot),
#endif
DLSYM_ARG(dwfl_report_end),
DLSYM_ARG(dwfl_getmodules),
DLSYM_ARG(dwfl_core_file_attach),
DLSYM_ARG(dwfl_end),
DLSYM_ARG(dwfl_errmsg),
DLSYM_ARG(dwfl_errno),
DLSYM_ARG(dwfl_build_id_find_elf),
DLSYM_ARG(dwfl_standard_find_debuginfo),
DLSYM_ARG(dwfl_thread_tid),
DLSYM_ARG(dwfl_thread_getframes),
DLSYM_ARG(dwfl_getthreads),
DLSYM_ARG(dwfl_offline_section_address));
if (r <= 0)
return r;
return 1;
#else
return -EOPNOTSUPP;
#endif
}
int dlopen_elf(void) {
#if HAVE_ELFUTILS
int r;
ELF_NOTE_DLOPEN("elf",
"Support for backtraces and reading ELF package metadata from core files",
ELF_NOTE_DLOPEN_PRIORITY_SUGGESTED,
"libelf.so.1");
r = dlopen_many_sym_or_warn(
&elf_dl, "libelf.so.1", LOG_DEBUG,
DLSYM_ARG(elf_begin),
DLSYM_ARG(elf_end),
DLSYM_ARG(elf_getphdrnum),
DLSYM_ARG(elf_getdata_rawchunk),
DLSYM_ARG(elf_errmsg),
DLSYM_ARG(elf_errno),
DLSYM_ARG(elf_memory),
DLSYM_ARG(elf_version),
DLSYM_ARG(gelf_getehdr),
DLSYM_ARG(gelf_getphdr),
DLSYM_ARG(gelf_getnote));
if (r <= 0)
return r;
return 1;
#else
return -EOPNOTSUPP;
#endif
}
#if HAVE_ELFUTILS
typedef struct StackContext {
MemStream m;
Dwfl *dwfl;
Elf *elf;
unsigned n_thread;
unsigned n_frame;
sd_json_variant **package_metadata;
sd_json_variant **dlopen_metadata;
Set **modules;
} StackContext;
static void stack_context_done(StackContext *c) {
assert(c);
memstream_done(&c->m);
if (c->dwfl) {
sym_dwfl_end(c->dwfl);
c->dwfl = NULL;
}
if (c->elf) {
sym_elf_end(c->elf);
c->elf = NULL;
}
}
DEFINE_TRIVIAL_CLEANUP_FUNC_FULL_RENAME(Elf *, sym_elf_end, elf_endp, NULL);
static int frame_callback(Dwfl_Frame *frame, void *userdata) {
StackContext *c = ASSERT_PTR(userdata);
Dwarf_Addr pc, pc_adjusted;
const char *fname = NULL, *symbol = NULL;
Dwfl_Module *module;
bool is_activation;
uint64_t module_offset = 0;
assert(frame);
if (c->n_frame >= FRAMES_MAX)
return DWARF_CB_ABORT;
if (!sym_dwfl_frame_pc(frame, &pc, &is_activation))
return DWARF_CB_ABORT;
pc_adjusted = pc - (is_activation ? 0 : 1);
module = sym_dwfl_addrmodule(c->dwfl, pc_adjusted);
if (module) {
Dwarf_Addr start, bias = 0;
Dwarf_Die *cudie;
cudie = sym_dwfl_module_addrdie(module, pc_adjusted, &bias);
if (cudie) {
_cleanup_free_ Dwarf_Die *scopes = NULL;
int n;
n = sym_dwarf_getscopes(cudie, pc_adjusted - bias, &scopes);
if (n > 0)
for (Dwarf_Die *s = scopes; s && s < scopes + n; s++) {
Dwarf_Attribute *a, space;
if (!IN_SET(sym_dwarf_tag(s), DW_TAG_subprogram, DW_TAG_inlined_subroutine, DW_TAG_entry_point))
continue;
a = sym_dwarf_attr_integrate(s, DW_AT_MIPS_linkage_name, &space);
if (!a)
a = sym_dwarf_attr_integrate(s, DW_AT_linkage_name, &space);
if (a)
symbol = sym_dwarf_formstring(a);
if (!symbol)
symbol = sym_dwarf_diename(s);
if (symbol)
break;
}
}
if (!symbol)
symbol = sym_dwfl_module_addrname(module, pc_adjusted);
fname = sym_dwfl_module_info(module, NULL, &start, NULL, NULL, NULL, NULL, NULL);
module_offset = pc - start;
}
if (c->m.f)
fprintf(c->m.f, "#%-2u 0x%016" PRIx64 " %s (%s + 0x%" PRIx64 ")\n", c->n_frame, (uint64_t) pc, strna(symbol), strna(fname), module_offset);
c->n_frame++;
return DWARF_CB_OK;
}
static int thread_callback(Dwfl_Thread *thread, void *userdata) {
StackContext *c = ASSERT_PTR(userdata);
pid_t tid;
assert(thread);
if (c->n_thread >= THREADS_MAX)
return DWARF_CB_ABORT;
if (c->n_thread != 0 && c->m.f)
fputc('\n', c->m.f);
c->n_frame = 0;
if (c->m.f) {
tid = sym_dwfl_thread_tid(thread);
fprintf(c->m.f, "Stack trace of thread " PID_FMT ":\n", tid);
}
if (sym_dwfl_thread_getframes(thread, frame_callback, c) < 0)
return DWARF_CB_ABORT;
c->n_thread++;
return DWARF_CB_OK;
}
static char* build_package_reference(
const char *type,
const char *name,
const char *version,
const char *arch) {
/* Construct an identifier for a specific version of the package. The syntax is most suitable for
* rpm: the resulting string can be used directly in queries and rpm/dnf/yum commands. For dpkg and
* other systems, it might not be usable directly, but users should still be able to figure out the
* meaning.
*/
return strjoin(type ?: "package",
" ",
name,
version ? "-" : "",
strempty(version),
/* arch is meaningful even without version, so always print it */
arch ? "." : "",
strempty(arch));
}
static void report_module_metadata(StackContext *c, const char *name, sd_json_variant *metadata) {
assert(c);
assert(name);
if (!c->m.f)
return;
fprintf(c->m.f, "Module %s", name);
if (metadata) {
const char
*build_id = sd_json_variant_string(sd_json_variant_by_key(metadata, "buildId")),
*type = sd_json_variant_string(sd_json_variant_by_key(metadata, "type")),
*package = sd_json_variant_string(sd_json_variant_by_key(metadata, "name")),
*version = sd_json_variant_string(sd_json_variant_by_key(metadata, "version")),
*arch = sd_json_variant_string(sd_json_variant_by_key(metadata, "architecture"));
if (package) {
/* Version/architecture is only meaningful with a package name.
* Skip the detailed fields if package is unknown. */
_cleanup_free_ char *id = build_package_reference(type, package, version, arch);
fprintf(c->m.f, " from %s", strnull(id));
}
if (build_id && !(package && version))
fprintf(c->m.f, ", build-id=%s", build_id);
}
fputs("\n", c->m.f);
}
static int parse_metadata(const char *name, sd_json_variant *id_json, Elf *elf, bool *ret_interpreter_found, StackContext *c) {
bool package_metadata_found = false, interpreter_found = false;
size_t n_program_headers;
int r;
assert(name);
assert(elf);
assert(c);
/* When iterating over PT_LOAD we will visit modules more than once */
if (set_contains(*c->modules, name))
return 0;
r = sym_elf_getphdrnum(elf, &n_program_headers);
if (r < 0) /* Not the handle we are looking for - that's ok, skip it */
return 0;
/* Iterate over all program headers in that ELF object. These will have been copied by
* the kernel verbatim when the core file is generated. */
for (size_t i = 0; i < n_program_headers; ++i) {
GElf_Phdr mem, *program_header;
GElf_Nhdr note_header;
Elf_Data *data;
/* Package metadata is in PT_NOTE headers. */
program_header = sym_gelf_getphdr(elf, i, &mem);
if (!program_header || !IN_SET(program_header->p_type, PT_NOTE, 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. */
data = sym_elf_getdata_rawchunk(elf,
program_header->p_offset,
program_header->p_filesz,
ELF_T_NHDR);
if (!data)
continue;
for (size_t note_offset = 0, name_offset, desc_offset;
note_offset < data->d_size &&
(note_offset = sym_gelf_getnote(data, note_offset, &note_header, &name_offset, &desc_offset)) > 0;) {
_cleanup_(sd_json_variant_unrefp) sd_json_variant *v = NULL, *w = NULL;
const char *payload = (const char *)data->d_buf + desc_offset;
if (note_header.n_namesz == 0 || note_header.n_descsz == 0)
continue;
/* Package metadata might have different owners, but the
* magic ID is always the same. */
if (!IN_SET(note_header.n_type, ELF_PACKAGE_METADATA_ID, ELF_NOTE_DLOPEN_TYPE))
continue;
_cleanup_free_ char *payload_0suffixed = NULL;
assert(note_offset > desc_offset);
size_t payload_len = note_offset - desc_offset;
/* If we are lucky and the payload is NUL-padded, we don't need to copy the string.
* But if happens to go all the way until the end of the buffer, make a copy. */
if (payload[payload_len-1] != '\0') {
payload_0suffixed = memdup_suffix0(payload, payload_len);
if (!payload_0suffixed)
return log_oom();
payload = payload_0suffixed;
}
r = sd_json_parse(payload, 0, &v, NULL, NULL);
if (r < 0) {
_cleanup_free_ char *esc = cescape(payload);
return log_error_errno(r, "json_parse on \"%s\" failed: %m", strnull(esc));
}
if (note_header.n_type == ELF_PACKAGE_METADATA_ID) {
/* If we have a build-id, merge it in the same JSON object so that it appears all
* nicely together in the logs/metadata. */
if (id_json) {
r = sd_json_variant_merge_object(&v, id_json);
if (r < 0)
return log_error_errno(r, "sd_json_variant_merge of package meta with buildId failed: %m");
}
/* Pretty-print to the buffer, so that the metadata goes as plaintext in the
* journal. */
report_module_metadata(c, name, v);
/* Then we build a new object using the module name as the key, and merge it
* with the previous parses, so that in the end it all fits together in a single
* JSON blob. */
r = sd_json_buildo(&w, SD_JSON_BUILD_PAIR(name, SD_JSON_BUILD_VARIANT(v)));
if (r < 0)
return log_error_errno(r, "Failed to build JSON object: %m");
r = sd_json_variant_merge_object(c->package_metadata, w);
if (r < 0)
return log_error_errno(r, "sd_json_variant_merge of package meta with buildId failed: %m");
package_metadata_found = true;
} else if (c->dlopen_metadata) {
sd_json_variant *z;
JSON_VARIANT_ARRAY_FOREACH(z, v) {
r = sd_json_variant_append_array(c->dlopen_metadata, z);
if (r < 0)
return log_error_errno(r, "Failed to append entry to dlopen metadata: %m");
}
}
/* Finally stash the name, so we avoid double visits. */
r = set_put_strdup(c->modules, name);
if (r < 0)
return log_error_errno(r, "set_put_strdup failed: %m");
if (!c->dlopen_metadata) {
if (ret_interpreter_found)
*ret_interpreter_found = interpreter_found;
return 1;
}
}
}
if (ret_interpreter_found)
*ret_interpreter_found = interpreter_found;
return c->dlopen_metadata ? 0 : package_metadata_found;
}
/* Get the build-id out of an ELF object or a dwarf core module. */
static int parse_buildid(Dwfl_Module *mod, Elf *elf, const char *name, StackContext *c, sd_json_variant **ret_id_json) {
_cleanup_(sd_json_variant_unrefp) sd_json_variant *id_json = NULL;
const unsigned char *id;
GElf_Addr id_vaddr;
ssize_t id_len;
int r;
assert(mod || elf);
assert(name);
assert(c);
if (mod)
id_len = sym_dwfl_module_build_id(mod, &id, &id_vaddr);
else
id_len = sym_dwelf_elf_gnu_build_id(elf, (const void **)&id);
if (id_len <= 0) {
/* If we don't find a build-id, note it in the journal message, and try
* anyway to find the package metadata. It's unlikely to have the latter
* without the former, but there's no hard rule. */
if (c->m.f)
fprintf(c->m.f, "Module %s without build-id.\n", name);
} else {
/* We will later parse package metadata json and pass it to our caller. Prepare the
* build-id in json format too, so that it can be appended and parsed cleanly. It
* will then be added as metadata to the journal message with the stack trace. */
r = sd_json_buildo(&id_json, SD_JSON_BUILD_PAIR("buildId", SD_JSON_BUILD_HEX(id, id_len)));
if (r < 0)
return log_error_errno(r, "json_build on buildId failed: %m");
}
if (ret_id_json)
*ret_id_json = TAKE_PTR(id_json);
return 0;
}
static int module_callback(Dwfl_Module *mod, void **userdata, const char *name, Dwarf_Addr start, void *arg) {
_cleanup_(sd_json_variant_unrefp) sd_json_variant *id_json = NULL;
StackContext *c = ASSERT_PTR(arg);
size_t n_program_headers;
GElf_Addr bias;
int r;
Elf *elf;
assert(mod);
if (!name)
name = "(unnamed)"; /* For logging purposes */
/* We are iterating on each "module", which is what dwfl calls ELF objects contained in the
* core file, and extracting the build-id first and then the package metadata.
* We proceed in a best-effort fashion - not all ELF objects might contain both or either.
* The build-id is easy, as libdwfl parses it during the sym_dwfl_core_file_report() call and
* stores it separately in an internal library struct. */
r = parse_buildid(mod, NULL, name, c, &id_json);
if (r < 0)
return DWARF_CB_ABORT;
/* The .note.package metadata is more difficult. From the module, we need to get a reference
* 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_metadata(name, id_json, elf, NULL, c);
if (r < 0)
return DWARF_CB_ABORT;
if (r > 0)
return DWARF_CB_OK;
} else
elf = c->elf;
/* We did not get the ELF object, or it's just a reference to the core. That is likely
* because we didn't get direct access to the executable, and the version of elfutils does
* not yet support parsing it out of the core file directly.
* So fallback to manual extraction - get the PT_LOAD section from the core,
* and if it's the right one we can interpret it as an Elf object, and parse
* its notes manually. */
r = sym_elf_getphdrnum(elf, &n_program_headers);
if (r < 0) {
log_warning("Could not parse number of program headers from core file: %s",
sym_elf_errmsg(-1)); /* -1 retrieves the most recent error */
report_module_metadata(c, name, id_json);
return DWARF_CB_OK;
}
for (size_t i = 0; i < n_program_headers; ++i) {
GElf_Phdr mem, *program_header;
Elf_Data *data;
GElf_Addr end_of_segment;
/* The core file stores the ELF files in the PT_LOAD segment. */
program_header = sym_gelf_getphdr(elf, i, &mem);
if (!program_header || program_header->p_type != PT_LOAD)
continue;
/* Check that the end of segment is a valid address. */
if (!ADD_SAFE(&end_of_segment, program_header->p_vaddr, program_header->p_memsz)) {
log_error("Abort due to corrupted core dump, end of segment address %#zx + %#zx overflows", (size_t)program_header->p_vaddr, (size_t)program_header->p_memsz);
return DWARF_CB_ABORT;
}
/* This PT_LOAD segment doesn't contain the start address, so it can't be the module we are looking for. */
if (start < program_header->p_vaddr || start >= end_of_segment)
continue;
/* Now get a usable Elf reference, and parse the notes from it. */
data = sym_elf_getdata_rawchunk(elf,
program_header->p_offset,
program_header->p_filesz,
ELF_T_NHDR);
if (!data)
continue;
_cleanup_(elf_endp) Elf *memelf = sym_elf_memory(data->d_buf, data->d_size);
if (!memelf)
continue;
r = parse_metadata(name, id_json, memelf, NULL, c);
if (r < 0)
return DWARF_CB_ABORT;
if (r > 0)
break;
}
return DWARF_CB_OK;
}
static int parse_core(
int fd,
const char *root,
char **ret,
sd_json_variant **ret_package_metadata,
sd_json_variant **ret_dlopen_metadata) {
const Dwfl_Callbacks callbacks = {
.find_elf = sym_dwfl_build_id_find_elf,
.section_address = sym_dwfl_offline_section_address,
.find_debuginfo = sym_dwfl_standard_find_debuginfo,
};
_cleanup_(sd_json_variant_unrefp) sd_json_variant *package_metadata = NULL, *dlopen_metadata = NULL;
_cleanup_set_free_ Set *modules = NULL;
_cleanup_(stack_context_done) StackContext c = {
.package_metadata = &package_metadata,
.dlopen_metadata = ret_dlopen_metadata ? &dlopen_metadata : NULL,
.modules = &modules,
};
int r;
assert(fd >= 0);
if (lseek(fd, 0, SEEK_SET) < 0)
return log_warning_errno(errno, "Failed to seek to beginning of the core file: %m");
if (ret && !memstream_init(&c.m))
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 core file, elf_begin() failed: %s", sym_elf_errmsg(sym_elf_errno()));
c.dwfl = sym_dwfl_begin(&callbacks);
if (!c.dwfl)
return log_warning_errno(SYNTHETIC_ERRNO(EINVAL), "Could not parse core file, dwfl_begin() failed: %s", sym_dwfl_errmsg(sym_dwfl_errno()));
if (empty_or_root(root))
root = NULL;
#if HAVE_DWFL_SET_SYSROOT
if (root && sym_dwfl_set_sysroot(c.dwfl, root) < 0)
return log_warning_errno(SYNTHETIC_ERRNO(EINVAL), "Could not set root directory, dwfl_set_sysroot() failed: %s", sym_dwfl_errmsg(sym_dwfl_errno()));
#else
if (root)
log_warning("Compiled without dwfl_set_sysroot() support, ignoring provided root directory.");
#endif
if (sym_dwfl_core_file_report(c.dwfl, c.elf, NULL) < 0)
return log_warning_errno(SYNTHETIC_ERRNO(EINVAL), "Could not parse core file, dwfl_core_file_report() failed: %s", sym_dwfl_errmsg(sym_dwfl_errno()));
if (sym_dwfl_report_end(c.dwfl, NULL, NULL) != 0)
return log_warning_errno(SYNTHETIC_ERRNO(EINVAL), "Could not parse core file, dwfl_report_end() failed: %s", sym_dwfl_errmsg(sym_dwfl_errno()));
if (sym_dwfl_getmodules(c.dwfl, &module_callback, &c, 0) < 0)
return log_warning_errno(SYNTHETIC_ERRNO(EINVAL), "Could not parse core file, dwfl_getmodules() failed: %s", sym_dwfl_errmsg(sym_dwfl_errno()));
if (sym_dwfl_core_file_attach(c.dwfl, c.elf) < 0)
return log_warning_errno(SYNTHETIC_ERRNO(EINVAL), "Could not parse core file, dwfl_core_file_attach() failed: %s", sym_dwfl_errmsg(sym_dwfl_errno()));
if (sym_dwfl_getthreads(c.dwfl, thread_callback, &c) < 0)
return log_warning_errno(SYNTHETIC_ERRNO(EINVAL), "Could not parse core file, dwfl_getthreads() failed: %s", sym_dwfl_errmsg(sym_dwfl_errno()));
if (ret) {
r = memstream_finalize(&c.m, ret, NULL);
if (r < 0)
return log_warning_errno(r, "Could not parse core file, flushing file buffer failed: %m");
}
if (ret_package_metadata)
*ret_package_metadata = TAKE_PTR(package_metadata);
if (ret_dlopen_metadata)
*ret_dlopen_metadata = TAKE_PTR(dlopen_metadata);
return 0;
}
static int parse_elf(
int fd,
const char *executable,
const char *root,
char **ret,
sd_json_variant **ret_package_metadata,
sd_json_variant **ret_dlopen_metadata) {
_cleanup_(sd_json_variant_unrefp) sd_json_variant *package_metadata = NULL, *dlopen_metadata = NULL, *elf_metadata = NULL;
_cleanup_set_free_ Set *modules = NULL;
_cleanup_(stack_context_done) StackContext c = {
.package_metadata = &package_metadata,
.dlopen_metadata = ret_dlopen_metadata ? &dlopen_metadata : NULL,
.modules = &modules,
};
const char *elf_type;
GElf_Ehdr elf_header;
int r;
assert(fd >= 0);
if (lseek(fd, 0, SEEK_SET) < 0)
return log_warning_errno(errno, "Failed to seek to beginning of the ELF file: %m");
if (ret && !memstream_init(&c.m))
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, root, ret ? &out : NULL, &package_metadata, &dlopen_metadata);
if (r < 0)
return log_warning_errno(r, "Failed to inspect core file: %m");
if (out)
fprintf(c.m.f, "%s", out);
elf_type = "coredump";
} else {
_cleanup_(sd_json_variant_unrefp) sd_json_variant *id_json = NULL;
const char *e = executable ?: "(unnamed)";
bool interpreter_found = false;
r = parse_buildid(NULL, c.elf, e, &c, &id_json);
if (r < 0)
return log_warning_errno(r, "Failed to parse build-id of ELF file: %m");
r = parse_metadata(e, 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 = sd_json_buildo(&package_metadata, SD_JSON_BUILD_PAIR(e, SD_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 = sd_json_buildo(&elf_metadata, SD_JSON_BUILD_PAIR("elfType", SD_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
const char *elf_architecture = sym_dwelf_elf_e_machine_string(elf_header.e_machine);
if (elf_architecture) {
r = sd_json_variant_merge_objectbo(
&elf_metadata,
SD_JSON_BUILD_PAIR("elfArchitecture", SD_JSON_BUILD_STRING(elf_architecture)));
if (r < 0)
return log_warning_errno(r, "Failed to add elfArchitecture field: %m");
if (ret)
fprintf(c.m.f, "ELF object binary architecture: %s\n", elf_architecture);
}
#endif
/* We always at least have the ELF type, so merge that (and possibly the arch). */
r = sd_json_variant_merge_object(&elf_metadata, package_metadata);
if (r < 0)
return log_warning_errno(r, "Failed to merge JSON objects: %m");
if (ret) {
r = memstream_finalize(&c.m, ret, NULL);
if (r < 0)
return log_warning_errno(r, "Could not parse ELF file, flushing file buffer failed: %m");
}
if (ret_package_metadata)
*ret_package_metadata = TAKE_PTR(elf_metadata);
if (ret_dlopen_metadata)
*ret_dlopen_metadata = TAKE_PTR(dlopen_metadata);
return 0;
}
#endif
int parse_elf_object(
int fd,
const char *executable,
const char *root,
bool fork_disable_dump,
char **ret,
sd_json_variant **ret_package_metadata,
sd_json_variant **ret_dlopen_metadata) {
#if HAVE_ELFUTILS
_cleanup_close_pair_ int error_pipe[2] = EBADF_PAIR,
return_pipe[2] = EBADF_PAIR,
package_metadata_pipe[2] = EBADF_PAIR,
dlopen_metadata_pipe[2] = EBADF_PAIR;
_cleanup_(sd_json_variant_unrefp) sd_json_variant *package_metadata = NULL, *dlopen_metadata = NULL;
_cleanup_free_ char *buf = NULL;
int r;
assert(fd >= 0);
r = dlopen_dw();
if (r < 0)
return r;
r = dlopen_elf();
if (r < 0)
return r;
r = RET_NERRNO(pipe2(error_pipe, O_CLOEXEC|O_NONBLOCK));
if (r < 0)
return r;
if (ret) {
r = RET_NERRNO(pipe2(return_pipe, O_CLOEXEC|O_NONBLOCK));
if (r < 0)
return r;
}
if (ret_package_metadata) {
r = RET_NERRNO(pipe2(package_metadata_pipe, O_CLOEXEC|O_NONBLOCK));
if (r < 0)
return r;
}
if (ret_dlopen_metadata) {
r = RET_NERRNO(pipe2(dlopen_metadata_pipe, O_CLOEXEC|O_NONBLOCK));
if (r < 0)
return r;
}
/* Parsing possibly malformed data is crash-happy, so fork. In case we crash,
* the core file will not be lost, and the messages will still be attached to
* the journal. Reading the elf object might be slow, but it still has an upper
* bound since the core files have an upper size limit. It's also not doing any
* system call or interacting with the system in any way, besides reading from
* the file descriptor and writing into these four pipes. */
r = safe_fork_full("(sd-parse-elf)",
NULL,
(int[]){ fd, error_pipe[1], return_pipe[1], package_metadata_pipe[1], dlopen_metadata_pipe[1] },
5,
FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_NEW_MOUNTNS|FORK_MOUNTNS_SLAVE|FORK_NEW_USERNS|FORK_WAIT|FORK_REOPEN_LOG,
NULL);
if (r < 0) {
if (r == -EPROTO) { /* We should have the errno from the child, but don't clobber original error */
ssize_t k;
int e;
k = read(error_pipe[0], &e, sizeof(e));
if (k < 0 && errno != EAGAIN) /* Pipe is non-blocking, EAGAIN means there's nothing */
return -errno;
if (k == sizeof(e))
return e; /* propagate error sent to us from child */
if (k != 0)
return -EIO;
}
return r;
}
if (r == 0) {
/* We want to avoid loops, given this can be called from systemd-coredump */
if (fork_disable_dump) {
r = set_dumpable(SUID_DUMP_DISABLE);
if (r < 0)
report_errno_and_exit(error_pipe[1], r);
}
r = parse_elf(
fd,
executable,
root,
ret ? &buf : NULL,
ret_package_metadata ? &package_metadata : NULL,
ret_dlopen_metadata ? &dlopen_metadata : NULL);
if (r < 0)
report_errno_and_exit(error_pipe[1], r);
if (buf) {
size_t len = strlen(buf);
if (len > COREDUMP_PIPE_MAX) {
/* This is iffy. A backtrace can be a few hundred kilobytes, but too much is
* too much. Let's log a warning and ignore the rest. */
log_warning("Generated backtrace is %zu bytes (more than the limit of %u bytes), backtrace will be truncated.",
len, COREDUMP_PIPE_MAX);
len = COREDUMP_PIPE_MAX;
}
/* Bump the space for the returned string.
* Failure is ignored, because partial output is still useful. */
(void) fcntl(return_pipe[1], F_SETPIPE_SZ, len);
r = loop_write(return_pipe[1], buf, len);
if (r == -EAGAIN)
log_warning("Write failed, backtrace will be truncated.");
else if (r < 0)
report_errno_and_exit(error_pipe[1], r);
return_pipe[1] = safe_close(return_pipe[1]);
}
if (package_metadata) {
_cleanup_fclose_ FILE *json_out = NULL;
/* Bump the space for the returned string. We don't know how much space we'll need in
* advance, so we'll just try to write as much as possible and maybe fail later. */
(void) fcntl(package_metadata_pipe[1], F_SETPIPE_SZ, COREDUMP_PIPE_MAX);
json_out = take_fdopen(&package_metadata_pipe[1], "w");
if (!json_out)
report_errno_and_exit(error_pipe[1], -errno);
r = sd_json_variant_dump(package_metadata, SD_JSON_FORMAT_FLUSH, json_out, NULL);
if (r < 0)
log_warning_errno(r, "Failed to write JSON package metadata, ignoring: %m");
}
if (dlopen_metadata) {
_cleanup_fclose_ FILE *json_out = NULL;
/* Bump the space for the returned string. We don't know how much space we'll need in
* advance, so we'll just try to write as much as possible and maybe fail later. */
(void) fcntl(dlopen_metadata_pipe[1], F_SETPIPE_SZ, COREDUMP_PIPE_MAX);
json_out = take_fdopen(&dlopen_metadata_pipe[1], "w");
if (!json_out)
report_errno_and_exit(error_pipe[1], -errno);
r = sd_json_variant_dump(dlopen_metadata, SD_JSON_FORMAT_FLUSH, json_out, NULL);
if (r < 0)
log_warning_errno(r, "Failed to write JSON package metadata, ignoring: %m");
}
_exit(EXIT_SUCCESS);
}
error_pipe[1] = safe_close(error_pipe[1]);
return_pipe[1] = safe_close(return_pipe[1]);
package_metadata_pipe[1] = safe_close(package_metadata_pipe[1]);
dlopen_metadata_pipe[1] = safe_close(dlopen_metadata_pipe[1]);
if (ret) {
_cleanup_fclose_ FILE *in = NULL;
in = take_fdopen(&return_pipe[0], "r");
if (!in)
return -errno;
r = read_full_stream(in, &buf, NULL);
if (r < 0)
return r;
}
if (ret_package_metadata) {
_cleanup_fclose_ FILE *json_in = NULL;
json_in = take_fdopen(&package_metadata_pipe[0], "r");
if (!json_in)
return -errno;
r = sd_json_parse_file(json_in, NULL, 0, &package_metadata, NULL, NULL);
if (r < 0 && r != -ENODATA) /* ENODATA: json was empty, so we got nothing, but that's ok */
log_warning_errno(r, "Failed to read or parse package metadata, ignoring: %m");
}
if (ret_dlopen_metadata) {
_cleanup_fclose_ FILE *json_in = NULL;
json_in = take_fdopen(&dlopen_metadata_pipe[0], "r");
if (!json_in)
return -errno;
r = sd_json_parse_file(json_in, NULL, 0, &dlopen_metadata, NULL, NULL);
if (r < 0 && r != -ENODATA) /* ENODATA: json was empty, so we got nothing, but that's ok */
log_warning_errno(r, "Failed to read or parse dlopen metadata, ignoring: %m");
}
if (ret)
*ret = TAKE_PTR(buf);
if (ret_package_metadata)
*ret_package_metadata = TAKE_PTR(package_metadata);
if (ret_dlopen_metadata)
*ret_dlopen_metadata = TAKE_PTR(dlopen_metadata);
return 0;
#else
return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "elfutils disabled, parsing ELF objects not supported");
#endif
}
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