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pid1: add ability to kill processes in a subgroup of a unit

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This is useful for things like machined, where the system machined wants
to manage a machine owned by the user somewhere down the tree.
This commit is contained in:
Lennart Poettering
2025-07-08 03:14:53 +02:00
parent 9afe65d974
commit 0f23564ad4
11 changed files with 183 additions and 50 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/core/dbus-manager.c
+11
View File
@@ -831,6 +831,12 @@ static int method_kill_unit(sd_bus_message *message, void *userdata, sd_bus_erro
return method_generic_unit_operation(message, userdata, error, bus_unit_method_kill, 0);
}
static int method_kill_unit_subgroup(sd_bus_message *message, void *userdata, sd_bus_error *error) {
/* We don't bother with GENERIC_UNIT_LOAD nor GENERIC_UNIT_VALIDATE_LOADED here, as it shouldn't
* matter whether a unit is loaded for killing any processes possibly in the unit's cgroup. */
return method_generic_unit_operation(message, userdata, error, bus_unit_method_kill_subgroup, 0);
}
static int method_clean_unit(sd_bus_message *message, void *userdata, sd_bus_error *error) {
/* Load the unit if necessary, in order to load it, and insist on the unit being loaded to be
* cleaned */
@@ -3025,6 +3031,11 @@ const sd_bus_vtable bus_manager_vtable[] = {
SD_BUS_NO_RESULT,
method_kill_unit,
SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_METHOD_WITH_ARGS("KillUnitSubgroup",
SD_BUS_ARGS("s", name, "s", whom, "s", subgroup, "i", signal),
SD_BUS_NO_RESULT,
method_kill_unit_subgroup,
SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_METHOD_WITH_ARGS("QueueSignalUnit",
SD_BUS_ARGS("s", name, "s", whom, "i", signal, "i", value),
SD_BUS_NO_RESULT,
src/core/dbus-unit.c
+59 -1
View File
@@ -572,7 +572,60 @@ int bus_unit_method_kill(sd_bus_message *message, void *userdata, sd_bus_error *
if (r == 0)
return 1; /* No authorization for now, but the async polkit stuff will call us again when it has it */
r = unit_kill(u, whom, signo, code, value, error);
r = unit_kill(u, whom, /* subgroup= */ NULL, signo, code, value, error);
if (r < 0)
return r;
return sd_bus_reply_method_return(message, NULL);
}
int bus_unit_method_kill_subgroup(sd_bus_message *message, void *userdata, sd_bus_error *error) {
Unit *u = ASSERT_PTR(userdata);
int r;
assert(message);
r = mac_selinux_unit_access_check(u, message, "stop", error);
if (r < 0)
return r;
const char *swhom, *subgroup;
int32_t signo;
r = sd_bus_message_read(message, "ssi", &swhom, &subgroup, &signo);
if (r < 0)
return r;
KillWhom whom;
if (isempty(swhom))
whom = KILL_CGROUP;
else {
whom = kill_whom_from_string(swhom);
if (whom < 0)
return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid whom argument: %s", swhom);
}
if (isempty(subgroup))
subgroup = NULL;
else if (!path_is_normalized(subgroup))
return sd_bus_error_set(error, SD_BUS_ERROR_INVALID_ARGS, "Specified cgroup sub-path is not valid.");
else if (!IN_SET(whom, KILL_CGROUP, KILL_CGROUP_FAIL))
return sd_bus_error_set(error, SD_BUS_ERROR_INVALID_ARGS, "Subgroup can only be specified in combination with 'cgroup' or 'cgroup-fail'.");
if (!SIGNAL_VALID(signo))
return sd_bus_error_set(error, SD_BUS_ERROR_INVALID_ARGS, "Signal number out of range.");
r = bus_verify_manage_units_async_full(
u,
"kill-subgroup",
N_("Authentication is required to send a UNIX signal to the processes of subgroup of '$(unit)'."),
message,
error);
if (r < 0)
return r;
if (r == 0)
return 1; /* No authorization for now, but the async polkit stuff will call us again when it has it */
r = unit_kill(u, whom, subgroup, signo, SI_USER, /* value= */ 0, error);
if (r < 0)
return r;
@@ -986,6 +1039,11 @@ const sd_bus_vtable bus_unit_vtable[] = {
SD_BUS_NO_RESULT,
bus_unit_method_kill,
SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_METHOD_WITH_ARGS("KillSubgroup",
SD_BUS_ARGS("s", subgroup, "i", signal),
SD_BUS_NO_RESULT,
bus_unit_method_kill_subgroup,
SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_METHOD_WITH_ARGS("QueueSignal",
SD_BUS_ARGS("s", whom, "i", signal, "i", value),
SD_BUS_NO_RESULT,
src/core/dbus-unit.h
+1
View File
@@ -16,6 +16,7 @@ void bus_unit_send_removed_signal(Unit *u);
int bus_unit_method_start_generic(sd_bus_message *message, Unit *u, JobType job_type, bool reload_if_possible, sd_bus_error *error);
int bus_unit_method_enqueue_job(sd_bus_message *message, void *userdata, sd_bus_error *error);
int bus_unit_method_kill(sd_bus_message *message, void *userdata, sd_bus_error *error);
int bus_unit_method_kill_subgroup(sd_bus_message *message, void *userdata, sd_bus_error *error);
int bus_unit_method_reset_failed(sd_bus_message *message, void *userdata, sd_bus_error *error);
int bus_unit_set_properties(Unit *u, sd_bus_message *message, UnitWriteFlags flags, bool commit, sd_bus_error *error);
src/core/kill.c
+2
View File
@@ -54,6 +54,8 @@ static const char* const kill_whom_table[_KILL_WHOM_MAX] = {
[KILL_MAIN_FAIL] = "main-fail",
[KILL_CONTROL_FAIL] = "control-fail",
[KILL_ALL_FAIL] = "all-fail",
[KILL_CGROUP] = "cgroup",
[KILL_CGROUP_FAIL] = "cgroup-fail",
};
DEFINE_STRING_TABLE_LOOKUP(kill_whom, KillWhom);
src/core/kill.h
+2
View File
@@ -31,6 +31,8 @@ typedef enum KillWhom {
KILL_MAIN_FAIL,
KILL_CONTROL_FAIL,
KILL_ALL_FAIL,
KILL_CGROUP,
KILL_CGROUP_FAIL,
_KILL_WHOM_MAX,
_KILL_WHOM_INVALID = -EINVAL,
} KillWhom;
src/core/org.freedesktop.systemd1.conf
+8
View File
@@ -246,6 +246,10 @@
send_interface="org.freedesktop.systemd1.Manager"
send_member="KillUnit"/>
<allow send_destination="org.freedesktop.systemd1"
send_interface="org.freedesktop.systemd1.Manager"
send_member="KillUnitSubgroup"/>
<allow send_destination="org.freedesktop.systemd1"
send_interface="org.freedesktop.systemd1.Manager"
send_member="QueueSignalUnit"/>
@@ -410,6 +414,10 @@
send_interface="org.freedesktop.systemd1.Unit"
send_member="Kill"/>
<allow send_destination="org.freedesktop.systemd1"
send_interface="org.freedesktop.systemd1.Unit"
send_member="KillSubgroup"/>
<allow send_destination="org.freedesktop.systemd1"
send_interface="org.freedesktop.systemd1.Unit"
send_member="QueueSignal"/>
src/core/unit.c
+35 -14
View File
@@ -4041,6 +4041,7 @@ static int unit_kill_one(
int unit_kill(
Unit *u,
KillWhom whom,
const char *subgroup,
int signo,
int code,
int value,
@@ -4060,11 +4061,19 @@ int unit_kill(
assert(SIGNAL_VALID(signo));
assert(IN_SET(code, SI_USER, SI_QUEUE));
if (subgroup) {
if (!IN_SET(whom, KILL_CGROUP, KILL_CGROUP_FAIL))
return sd_bus_error_set(ret_error, SD_BUS_ERROR_NOT_SUPPORTED, "Killing by subgroup is only supported for 'cgroup' or 'cgroup-kill' modes.");
if (!unit_cgroup_delegate(u))
return sd_bus_error_set(ret_error, SD_BUS_ERROR_NOT_SUPPORTED, "Killing by subgroup is only available for units with control group delegation enabled.");
}
main_pid = unit_main_pid(u);
control_pid = unit_control_pid(u);
if (!UNIT_HAS_CGROUP_CONTEXT(u) && !main_pid && !control_pid)
return sd_bus_error_setf(ret_error, SD_BUS_ERROR_NOT_SUPPORTED, "Unit type does not support process killing.");
return sd_bus_error_set(ret_error, SD_BUS_ERROR_NOT_SUPPORTED, "Unit type does not support process killing.");
if (IN_SET(whom, KILL_MAIN, KILL_MAIN_FAIL)) {
if (!main_pid)
@@ -4095,46 +4104,58 @@ int unit_kill(
/* Note: if we shall enqueue rather than kill we won't do this via the cgroup mechanism, since it
* doesn't really make much sense (and given that enqueued values are a relatively expensive
* resource, and we shouldn't allow us to be subjects for such allocation sprees) */
if (IN_SET(whom, KILL_ALL, KILL_ALL_FAIL) && code == SI_USER) {
if (IN_SET(whom, KILL_ALL, KILL_ALL_FAIL, KILL_CGROUP, KILL_CGROUP_FAIL) && code == SI_USER) {
CGroupRuntime *crt = unit_get_cgroup_runtime(u);
if (crt && crt->cgroup_path) {
_cleanup_set_free_ Set *pid_set = NULL;
_cleanup_free_ char *joined = NULL;
const char *p;
if (empty_or_root(subgroup))
p = crt->cgroup_path;
else {
joined = path_join(crt->cgroup_path, subgroup);
if (!joined)
return -ENOMEM;
p = joined;
}
if (signo == SIGKILL) {
r = cg_kill_kernel_sigkill(crt->cgroup_path);
r = cg_kill_kernel_sigkill(p);
if (r >= 0) {
killed = true;
log_unit_info(u, "Killed unit cgroup with SIGKILL on client request.");
log_unit_info(u, "Killed unit cgroup '%s' with SIGKILL on client request.", p);
goto finish;
}
if (r != -EOPNOTSUPP) {
if (ret >= 0)
sd_bus_error_set_errnof(ret_error, r,
"Failed to kill unit cgroup: %m");
RET_GATHER(ret, log_unit_warning_errno(u, r, "Failed to kill unit cgroup: %m"));
RET_GATHER(ret, log_unit_warning_errno(u, r, "Failed to kill unit cgroup '%s': %m", p));
goto finish;
}
/* Fall back to manual enumeration */
} else {
/* Exclude the main/control pids from being killed via the cgroup if
* not SIGKILL */
} else if (IN_SET(whom, KILL_ALL, KILL_ALL_FAIL)) {
/* Exclude the main/control pids from being killed via the cgroup if not
* SIGKILL */
r = unit_pid_set(u, &pid_set);
if (r < 0)
return log_oom();
}
r = cg_kill_recursive(crt->cgroup_path, signo, 0, pid_set, kill_common_log, u);
r = cg_kill_recursive(p, signo, /* flags= */ 0, pid_set, kill_common_log, u);
if (r < 0 && !IN_SET(r, -ESRCH, -ENOENT)) {
if (ret >= 0)
sd_bus_error_set_errnof(
ret_error, r,
"Failed to send signal SIG%s to auxiliary processes: %m",
signal_to_string(signo));
"Failed to send signal SIG%s to processes in unit cgroup '%s': %m",
signal_to_string(signo), p);
RET_GATHER(ret, log_unit_warning_errno(
u, r,
"Failed to send signal SIG%s to auxiliary processes on client request: %m",
signal_to_string(signo)));
"Failed to send signal SIG%s to processes in unit cgroup '%s' on client request: %m",
signal_to_string(signo), p));
}
killed = killed || r > 0;
}
@@ -4142,7 +4163,7 @@ int unit_kill(
finish:
/* If the "fail" versions of the operation are requested, then complain if the set of processes we killed is empty */
if (ret >= 0 && !killed && IN_SET(whom, KILL_ALL_FAIL, KILL_CONTROL_FAIL, KILL_MAIN_FAIL))
if (ret >= 0 && !killed && IN_SET(whom, KILL_ALL_FAIL, KILL_CONTROL_FAIL, KILL_MAIN_FAIL, KILL_CGROUP_FAIL))
return sd_bus_error_set_const(ret_error, BUS_ERROR_NO_SUCH_PROCESS, "No matching processes to kill");
return ret;
src/core/unit.h
+1 -1
View File
@@ -886,7 +886,7 @@ int unit_start(Unit *u, ActivationDetails *details);
int unit_stop(Unit *u);
int unit_reload(Unit *u);
int unit_kill(Unit *u, KillWhom w, int signo, int code, int value, sd_bus_error *ret_error);
int unit_kill(Unit *u, KillWhom w, const char *subgroup, int signo, int code, int value, sd_bus_error *ret_error);
void unit_notify_cgroup_oom(Unit *u, bool managed_oom);