/* Check that MOD is valid and make sure its relocation has been done. */
static bool
check_module (Dwfl_Module *mod)
{
if (INTUSE(dwfl_module_getsymtab) (mod) < 0)
{
Dwfl_Error error = dwfl_errno ();
if (error != DWFL_E_NO_SYMTAB)
{
__libdwfl_seterrno (error);
return true;
}
}
if (mod->dw == NULL)
{
Dwarf_Addr bias;
if (INTUSE(dwfl_module_getdwarf) (mod, &bias) == NULL)
{
Dwfl_Error error = dwfl_errno ();
if (error != DWFL_E_NO_DWARF)
{
__libdwfl_seterrno (error);
return true;
}
}
}
return false;
}
// Create a libdw session with DWARF information for all loaded modules
LibdwSession *libdwInit() {
LibdwSession *session = stgCallocBytes(1, sizeof(LibdwSession),
"libdwInit");
// Initialize ELF library
if (elf_version(EV_CURRENT) == EV_NONE) {
sysErrorBelch("libelf version too old!");
return NULL;
}
// Initialize a libdwfl session
static char *debuginfo_path;
static const Dwfl_Callbacks proc_callbacks =
{
.find_debuginfo = dwfl_standard_find_debuginfo,
.debuginfo_path = &debuginfo_path,
.find_elf = dwfl_linux_proc_find_elf,
};
session->dwfl = dwfl_begin (&proc_callbacks);
if (session->dwfl == NULL) {
sysErrorBelch("dwfl_begin failed: %s", dwfl_errmsg(dwfl_errno()));
free(session);
return NULL;
}
// Report the loaded modules
int ret = dwfl_linux_proc_report(session->dwfl, getpid());
if (ret < 0) {
sysErrorBelch("dwfl_linux_proc_report failed: %s",
dwfl_errmsg(dwfl_errno()));
goto fail;
}
if (dwfl_report_end (session->dwfl, NULL, NULL) != 0) {
sysErrorBelch("dwfl_report_end failed: %s", dwfl_errmsg(dwfl_errno()));
goto fail;
}
pid_t pid = getpid();
if (! dwfl_attach_state(session->dwfl, NULL, pid, &thread_cbs, NULL)) {
sysErrorBelch("dwfl_attach_state failed: %s",
dwfl_errmsg(dwfl_errno()));
goto fail;
}
return session;
fail:
dwfl_end(session->dwfl);
free(session);
return NULL;
}
Backtrace *libdwGetBacktrace(LibdwSession *session) {
if (session->cur_bt != NULL) {
sysErrorBelch("Already collecting backtrace. Uh oh.");
return NULL;
}
Backtrace *bt = backtraceAlloc();
session->cur_bt = bt;
int pid = getpid();
int ret = dwfl_getthread_frames(session->dwfl, pid,
getBacktraceFrameCb, session);
if (ret == -1)
sysErrorBelch("Failed to get stack frames of current process: %s",
dwfl_errmsg(dwfl_errno()));
session->cur_bt = NULL;
return bt;
}
int main(int argc, char* argv[]) {
/* The small core field we allocate on the stack, to keep things simple */
char
*core_pid = NULL, *core_uid = NULL, *core_gid = NULL, *core_signal = NULL,
*core_session = NULL, *core_exe = NULL, *core_comm = NULL, *core_cmdline = NULL,
*core_cgroup = NULL, *core_cwd = NULL, *core_root = NULL, *core_unit = NULL,
*core_slice = NULL;
/* The larger ones we allocate on the heap */
_cleanup_free_ char
*core_timestamp = NULL, *core_message = NULL, *coredump_data = NULL, *core_owner_uid = NULL,
*core_open_fds = NULL, *core_proc_status = NULL, *core_proc_maps = NULL, *core_proc_limits = NULL,
*core_proc_cgroup = NULL, *core_environ = NULL;
_cleanup_free_ char *exe = NULL, *comm = NULL, *filename = NULL;
const char *info[_INFO_LEN];
_cleanup_close_ int coredump_fd = -1;
struct iovec iovec[26];
uint64_t coredump_size;
int r, j = 0;
uid_t uid, owner_uid;
gid_t gid;
pid_t pid;
char *t;
const char *p;
/* Make sure we never enter a loop */
prctl(PR_SET_DUMPABLE, 0);
/* First, log to a safe place, since we don't know what
* crashed and it might be journald which we'd rather not log
* to then. */
log_set_target(LOG_TARGET_KMSG);
log_open();
if (argc < INFO_COMM + 1) {
log_error("Not enough arguments passed from kernel (%d, expected %d).",
argc - 1, INFO_COMM + 1 - 1);
r = -EINVAL;
goto finish;
}
/* Ignore all parse errors */
parse_config();
log_debug("Selected storage '%s'.", coredump_storage_to_string(arg_storage));
log_debug("Selected compression %s.", yes_no(arg_compress));
r = parse_uid(argv[INFO_UID + 1], &uid);
if (r < 0) {
log_error("Failed to parse UID.");
goto finish;
}
r = parse_pid(argv[INFO_PID + 1], &pid);
if (r < 0) {
log_error("Failed to parse PID.");
goto finish;
}
r = parse_gid(argv[INFO_GID + 1], &gid);
if (r < 0) {
log_error("Failed to parse GID.");
goto finish;
}
if (get_process_comm(pid, &comm) < 0) {
log_warning("Failed to get COMM, falling back to the command line.");
comm = strv_join(argv + INFO_COMM + 1, " ");
}
if (get_process_exe(pid, &exe) < 0)
log_warning("Failed to get EXE.");
info[INFO_PID] = argv[INFO_PID + 1];
info[INFO_UID] = argv[INFO_UID + 1];
info[INFO_GID] = argv[INFO_GID + 1];
info[INFO_SIGNAL] = argv[INFO_SIGNAL + 1];
info[INFO_TIMESTAMP] = argv[INFO_TIMESTAMP + 1];
info[INFO_COMM] = comm;
info[INFO_EXE] = exe;
if (cg_pid_get_unit(pid, &t) >= 0) {
if (streq(t, SPECIAL_JOURNALD_SERVICE)) {
free(t);
/* If we are journald, we cut things short,
* don't write to the journal, but still
* create a coredump. */
if (arg_storage != COREDUMP_STORAGE_NONE)
arg_storage = COREDUMP_STORAGE_EXTERNAL;
r = save_external_coredump(info, uid, &filename, &coredump_fd, &coredump_size);
if (r < 0)
goto finish;
r = maybe_remove_external_coredump(filename, coredump_size);
if (r < 0)
goto finish;
log_info("Detected coredump of the journal daemon itself, diverted to %s.", filename);
goto finish;
}
core_unit = strjoina("COREDUMP_UNIT=", t);
free(t);
} else if (cg_pid_get_user_unit(pid, &t) >= 0) {
core_unit = strjoina("COREDUMP_USER_UNIT=", t);
free(t);
}
if (core_unit)
IOVEC_SET_STRING(iovec[j++], core_unit);
/* OK, now we know it's not the journal, hence we can make use
* of it now. */
log_set_target(LOG_TARGET_JOURNAL_OR_KMSG);
log_open();
core_pid = strjoina("COREDUMP_PID=", info[INFO_PID]);
IOVEC_SET_STRING(iovec[j++], core_pid);
core_uid = strjoina("COREDUMP_UID=", info[INFO_UID]);
IOVEC_SET_STRING(iovec[j++], core_uid);
core_gid = strjoina("COREDUMP_GID=", info[INFO_GID]);
IOVEC_SET_STRING(iovec[j++], core_gid);
core_signal = strjoina("COREDUMP_SIGNAL=", info[INFO_SIGNAL]);
IOVEC_SET_STRING(iovec[j++], core_signal);
if (sd_pid_get_session(pid, &t) >= 0) {
core_session = strjoina("COREDUMP_SESSION=", t);
free(t);
IOVEC_SET_STRING(iovec[j++], core_session);
}
if (sd_pid_get_owner_uid(pid, &owner_uid) >= 0) {
r = asprintf(&core_owner_uid,
"COREDUMP_OWNER_UID=" UID_FMT, owner_uid);
if (r > 0)
IOVEC_SET_STRING(iovec[j++], core_owner_uid);
}
if (sd_pid_get_slice(pid, &t) >= 0) {
core_slice = strjoina("COREDUMP_SLICE=", t);
free(t);
IOVEC_SET_STRING(iovec[j++], core_slice);
}
if (comm) {
core_comm = strjoina("COREDUMP_COMM=", comm);
IOVEC_SET_STRING(iovec[j++], core_comm);
}
if (exe) {
core_exe = strjoina("COREDUMP_EXE=", exe);
IOVEC_SET_STRING(iovec[j++], core_exe);
}
if (get_process_cmdline(pid, 0, false, &t) >= 0) {
core_cmdline = strjoina("COREDUMP_CMDLINE=", t);
free(t);
IOVEC_SET_STRING(iovec[j++], core_cmdline);
}
if (cg_pid_get_path_shifted(pid, NULL, &t) >= 0) {
core_cgroup = strjoina("COREDUMP_CGROUP=", t);
free(t);
IOVEC_SET_STRING(iovec[j++], core_cgroup);
}
if (compose_open_fds(pid, &t) >= 0) {
core_open_fds = strappend("COREDUMP_OPEN_FDS=", t);
free(t);
if (core_open_fds)
IOVEC_SET_STRING(iovec[j++], core_open_fds);
}
p = procfs_file_alloca(pid, "status");
if (read_full_file(p, &t, NULL) >= 0) {
core_proc_status = strappend("COREDUMP_PROC_STATUS=", t);
free(t);
if (core_proc_status)
IOVEC_SET_STRING(iovec[j++], core_proc_status);
}
p = procfs_file_alloca(pid, "maps");
if (read_full_file(p, &t, NULL) >= 0) {
core_proc_maps = strappend("COREDUMP_PROC_MAPS=", t);
free(t);
if (core_proc_maps)
IOVEC_SET_STRING(iovec[j++], core_proc_maps);
}
p = procfs_file_alloca(pid, "limits");
if (read_full_file(p, &t, NULL) >= 0) {
core_proc_limits = strappend("COREDUMP_PROC_LIMITS=", t);
free(t);
if (core_proc_limits)
IOVEC_SET_STRING(iovec[j++], core_proc_limits);
}
p = procfs_file_alloca(pid, "cgroup");
if (read_full_file(p, &t, NULL) >=0) {
core_proc_cgroup = strappend("COREDUMP_PROC_CGROUP=", t);
free(t);
if (core_proc_cgroup)
IOVEC_SET_STRING(iovec[j++], core_proc_cgroup);
}
if (get_process_cwd(pid, &t) >= 0) {
core_cwd = strjoina("COREDUMP_CWD=", t);
free(t);
IOVEC_SET_STRING(iovec[j++], core_cwd);
}
if (get_process_root(pid, &t) >= 0) {
core_root = strjoina("COREDUMP_ROOT=", t);
free(t);
IOVEC_SET_STRING(iovec[j++], core_root);
}
if (get_process_environ(pid, &t) >= 0) {
core_environ = strappend("COREDUMP_ENVIRON=", t);
free(t);
if (core_environ)
IOVEC_SET_STRING(iovec[j++], core_environ);
}
core_timestamp = strjoin("COREDUMP_TIMESTAMP=", info[INFO_TIMESTAMP], "000000", NULL);
if (core_timestamp)
IOVEC_SET_STRING(iovec[j++], core_timestamp);
IOVEC_SET_STRING(iovec[j++], "MESSAGE_ID=fc2e22bc6ee647b6b90729ab34a250b1");
IOVEC_SET_STRING(iovec[j++], "PRIORITY=2");
/* Vacuum before we write anything again */
coredump_vacuum(-1, arg_keep_free, arg_max_use);
/* Always stream the coredump to disk, if that's possible */
r = save_external_coredump(info, uid, &filename, &coredump_fd, &coredump_size);
if (r < 0)
/* skip whole core dumping part */
goto log;
/* If we don't want to keep the coredump on disk, remove it
* now, as later on we will lack the privileges for
* it. However, we keep the fd to it, so that we can still
* process it and log it. */
r = maybe_remove_external_coredump(filename, coredump_size);
if (r < 0)
goto finish;
if (r == 0) {
const char *coredump_filename;
coredump_filename = strjoina("COREDUMP_FILENAME=", filename);
IOVEC_SET_STRING(iovec[j++], coredump_filename);
}
/* Vacuum again, but exclude the coredump we just created */
coredump_vacuum(coredump_fd, arg_keep_free, arg_max_use);
/* Now, let's drop privileges to become the user who owns the
* segfaulted process and allocate the coredump memory under
* the user's uid. This also ensures that the credentials
* journald will see are the ones of the coredumping user,
* thus making sure the user gets access to the core
* dump. Let's also get rid of all capabilities, if we run as
* root, we won't need them anymore. */
r = drop_privileges(uid, gid, 0);
if (r < 0) {
log_error_errno(r, "Failed to drop privileges: %m");
goto finish;
}
#ifdef HAVE_ELFUTILS
/* Try to get a strack trace if we can */
if (coredump_size <= arg_process_size_max) {
_cleanup_free_ char *stacktrace = NULL;
r = coredump_make_stack_trace(coredump_fd, exe, &stacktrace);
if (r >= 0)
core_message = strjoin("MESSAGE=Process ", info[INFO_PID], " (", comm, ") of user ", info[INFO_UID], " dumped core.\n\n", stacktrace, NULL);
else if (r == -EINVAL)
log_warning("Failed to generate stack trace: %s", dwfl_errmsg(dwfl_errno()));
else
log_warning_errno(r, "Failed to generate stack trace: %m");
}
if (!core_message)
#endif
log:
core_message = strjoin("MESSAGE=Process ", info[INFO_PID], " (", comm, ") of user ", info[INFO_UID], " dumped core.", NULL);
if (core_message)
IOVEC_SET_STRING(iovec[j++], core_message);
/* Optionally store the entire coredump in the journal */
if (IN_SET(arg_storage, COREDUMP_STORAGE_JOURNAL, COREDUMP_STORAGE_BOTH) &&
coredump_size <= arg_journal_size_max) {
size_t sz = 0;
/* Store the coredump itself in the journal */
r = allocate_journal_field(coredump_fd, (size_t) coredump_size, &coredump_data, &sz);
if (r >= 0) {
iovec[j].iov_base = coredump_data;
iovec[j].iov_len = sz;
j++;
}
}
r = sd_journal_sendv(iovec, j);
if (r < 0)
log_error_errno(r, "Failed to log coredump: %m");
finish:
return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
}
/* This is just doing dwfl_module_getsym, except that we must always use
the symbol table in RELOCATED itself when it has one, not MOD->symfile. */
static Dwfl_Error
relocate_getsym (Dwfl_Module *mod,
Elf *relocated, struct reloc_symtab_cache *cache,
int symndx, GElf_Sym *sym, GElf_Word *shndx)
{
if (cache->symdata == NULL)
{
if (mod->symfile == NULL || mod->symfile->elf != relocated)
{
/* We have to look up the symbol table in the file we are
relocating, if it has its own. These reloc sections refer to
the symbol table in this file, and a symbol table in the main
file might not match. However, some tools did produce ET_REL
.debug files with relocs but no symtab of their own. */
Elf_Scn *scn = NULL;
while ((scn = elf_nextscn (relocated, scn)) != NULL)
{
GElf_Shdr shdr_mem, *shdr = gelf_getshdr (scn, &shdr_mem);
if (shdr != NULL)
switch (shdr->sh_type)
{
default:
continue;
case SHT_SYMTAB:
cache->symelf = relocated;
cache->symdata = elf_getdata (scn, NULL);
cache->strtabndx = shdr->sh_link;
if (unlikely (cache->symdata == NULL))
return DWFL_E_LIBELF;
break;
case SHT_SYMTAB_SHNDX:
cache->symxndxdata = elf_getdata (scn, NULL);
if (unlikely (cache->symxndxdata == NULL))
return DWFL_E_LIBELF;
break;
}
if (cache->symdata != NULL && cache->symxndxdata != NULL)
break;
}
}
if (cache->symdata == NULL)
{
/* We might not have looked for a symbol table file yet,
when coming from __libdwfl_relocate_section. */
if (unlikely (mod->symfile == NULL)
&& unlikely (INTUSE(dwfl_module_getsymtab) (mod) < 0))
return dwfl_errno ();
/* The symbol table we have already cached is the one from
the file being relocated, so it's what we need. Or else
this is an ET_REL .debug file with no .symtab of its own;
the symbols refer to the section indices in the main file. */
cache->symelf = mod->symfile->elf;
cache->symdata = mod->symdata;
cache->symxndxdata = mod->symxndxdata;
cache->symstrdata = mod->symstrdata;
}
}
if (unlikely (gelf_getsymshndx (cache->symdata, cache->symxndxdata,
symndx, sym, shndx) == NULL))
return DWFL_E_LIBELF;
if (sym->st_shndx != SHN_XINDEX)
*shndx = sym->st_shndx;
switch (sym->st_shndx)
{
case SHN_ABS:
case SHN_UNDEF:
return DWFL_E_NOERROR;
case SHN_COMMON:
sym->st_value = 0; /* Value is size, not helpful. */
return DWFL_E_NOERROR;
}
return __libdwfl_relocate_value (mod, cache->symelf, &cache->symshstrndx,
*shndx, &sym->st_value);
}