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elf-util: Add support for parsing dlopen metadata

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Then we can add support for showing dlopen metadata to systemd-analyze.
This commit is contained in:
Daan De Meyer
2025-10-26 19:33:30 +01:00
parent f54d72c2b6
commit 004b7f1f7e
4 changed files with 149 additions and 50 deletions
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9
src/analyze/analyze-inspect-elf.c
View File

@@ -27,7 +27,14 @@ static int analyze_elf(char **filenames, sd_json_format_flags_t json_flags) {
if (fd < 0)
return log_error_errno(fd, "Could not open \"%s\": %m", *filename);
r = parse_elf_object(fd, abspath, arg_root, /* fork_disable_dump= */false, &stacktrace, &package_metadata);
r = parse_elf_object(
fd,
abspath,
arg_root,
/* fork_disable_dump= */ false,
&stacktrace,
&package_metadata,
/* ret_dlopen_metadata= */ NULL);
if (r < 0)
return log_error_errno(r, "Parsing \"%s\" as ELF object failed: %m", abspath);

3
src/coredump/coredump-submit.c
View File

@@ -689,7 +689,8 @@ int coredump_submit(
root,
/* fork_disable_dump= */ skip, /* avoid loops */
&stacktrace,
&json_metadata);
&json_metadata,
/* ret_dlopen_metadata= */ NULL);
}
}

178
src/shared/elf-util.c
View File

@@ -20,6 +20,7 @@
#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"
@@ -186,6 +187,7 @@ typedef struct StackContext {
unsigned n_thread;
unsigned n_frame;
sd_json_variant **package_metadata;
sd_json_variant **dlopen_metadata;
Set **modules;
} StackContext;
@@ -352,8 +354,8 @@ static void report_module_metadata(StackContext *c, const char *name, sd_json_va
fputs("\n", c->m.f);
}
static int parse_package_metadata(const char *name, sd_json_variant *id_json, Elf *elf, bool *ret_interpreter_found, StackContext *c) {
bool interpreter_found = false;
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;
@@ -408,7 +410,7 @@ static int parse_package_metadata(const char *name, sd_json_variant *id_json, El
/* Package metadata might have different owners, but the
* magic ID is always the same. */
if (note_header.n_type != ELF_PACKAGE_METADATA_ID)
if (!IN_SET(note_header.n_type, ELF_PACKAGE_METADATA_ID, ELF_NOTE_DLOPEN_TYPE))
continue;
_cleanup_free_ char *payload_0suffixed = NULL;
@@ -430,46 +432,59 @@ static int parse_package_metadata(const char *name, sd_json_variant *id_json, El
return log_error_errno(r, "json_parse on \"%s\" failed: %m", strnull(esc));
}
/* 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 (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");
}
}
/* 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");
/* 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 (ret_interpreter_found)
*ret_interpreter_found = interpreter_found;
if (!c->dlopen_metadata) {
if (ret_interpreter_found)
*ret_interpreter_found = interpreter_found;
return 1;
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;
return c->dlopen_metadata ? 0 : package_metadata_found;
}
/* Get the build-id out of an ELF object or a dwarf core module. */
@@ -535,7 +550,7 @@ 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, NULL, c);
r = parse_metadata(name, id_json, elf, NULL, c);
if (r < 0)
return DWARF_CB_ABORT;
if (r > 0)
@@ -590,7 +605,8 @@ static int module_callback(Dwfl_Module *mod, void **userdata, const char *name,
_cleanup_(elf_endp) Elf *memelf = sym_elf_memory(data->d_buf, data->d_size);
if (!memelf)
continue;
r = parse_package_metadata(name, id_json, memelf, NULL, c);
r = parse_metadata(name, id_json, memelf, NULL, c);
if (r < 0)
return DWARF_CB_ABORT;
if (r > 0)
@@ -600,7 +616,12 @@ static int module_callback(Dwfl_Module *mod, void **userdata, const char *name,
return DWARF_CB_OK;
}
static int parse_core(int fd, const char *root, char **ret, sd_json_variant **ret_package_metadata) {
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,
@@ -608,10 +629,11 @@ static int parse_core(int fd, const char *root, char **ret, sd_json_variant **re
.find_debuginfo = sym_dwfl_standard_find_debuginfo,
};
_cleanup_(sd_json_variant_unrefp) sd_json_variant *package_metadata = NULL;
_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;
@@ -667,15 +689,24 @@ static int parse_core(int fd, const char *root, char **ret, sd_json_variant **re
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) {
_cleanup_(sd_json_variant_unrefp) sd_json_variant *package_metadata = NULL, *elf_metadata = NULL;
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;
@@ -702,7 +733,7 @@ static int parse_elf(int fd, const char *executable, const char *root, char **re
if (elf_header.e_type == ET_CORE) {
_cleanup_free_ char *out = NULL;
r = parse_core(fd, root, ret ? &out : NULL, &package_metadata);
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");
@@ -719,7 +750,7 @@ static int parse_elf(int fd, const char *executable, const char *root, char **re
if (r < 0)
return log_warning_errno(r, "Failed to parse build-id of ELF file: %m");
r = parse_package_metadata(e, id_json, c.elf, &interpreter_found, &c);
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");
@@ -769,18 +800,28 @@ static int parse_elf(int fd, const char *executable, const char *root, char **re
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) {
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,
json_pipe[2] = EBADF_PAIR;
_cleanup_(sd_json_variant_unrefp) sd_json_variant *package_metadata = NULL;
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;
@@ -805,7 +846,13 @@ int parse_elf_object(int fd, const char *executable, const char *root, bool fork
}
if (ret_package_metadata) {
r = RET_NERRNO(pipe2(json_pipe, O_CLOEXEC|O_NONBLOCK));
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;
}
@@ -818,8 +865,8 @@ int parse_elf_object(int fd, const char *executable, const char *root, bool fork
* 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], json_pipe[1] },
4,
(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) {
@@ -846,7 +893,13 @@ int parse_elf_object(int fd, const char *executable, const char *root, bool fork
report_errno_and_exit(error_pipe[1], r);
}
r = parse_elf(fd, executable, root, ret ? &buf : NULL, ret_package_metadata ? &package_metadata : NULL);
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);
@@ -879,9 +932,9 @@ int parse_elf_object(int fd, const char *executable, const char *root, bool fork
/* 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(json_pipe[1], F_SETPIPE_SZ, COREDUMP_PIPE_MAX);
(void) fcntl(package_metadata_pipe[1], F_SETPIPE_SZ, COREDUMP_PIPE_MAX);
json_out = take_fdopen(&json_pipe[1], "w");
json_out = take_fdopen(&package_metadata_pipe[1], "w");
if (!json_out)
report_errno_and_exit(error_pipe[1], -errno);
@@ -890,12 +943,29 @@ int parse_elf_object(int fd, const char *executable, const char *root, bool fork
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]);
json_pipe[1] = safe_close(json_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;
@@ -912,19 +982,33 @@ int parse_elf_object(int fd, const char *executable, const char *root, bool fork
if (ret_package_metadata) {
_cleanup_fclose_ FILE *json_in = NULL;
json_in = take_fdopen(&json_pipe[0], "r");
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 json metadata, ignoring: %m");
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

9
src/shared/elf-util.h
View File

@@ -9,4 +9,11 @@ int dlopen_elf(void);
/* Parse an ELF object in a forked process, so that errors while iterating over
* untrusted and potentially malicious data do not propagate to the main caller's process.
* If fork_disable_dump, the child process will not dump core if it crashes. */
int parse_elf_object(int fd, const char *executable, const char *root, bool fork_disable_dump, char **ret, sd_json_variant **ret_package_metadata);
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);