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service: place control command in subcgroup control/

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Previously, we were brutally and onconditionally killing all processes
in a service's cgroup before starting the service anew, in order to
ensure that StartPre lines cannot be misused to spawn long-running
processes.

On logind-less systems this has the effect that restarting sshd
necessarily calls all active ssh sessions, which is usually not
desirable.

With this patch control processes for a service are placed in a
sub-cgroup called "control/". When starting a service anew we simply
kill this cgroup, but not the main cgroup, in order to avoid killing any
long-running non-control processes from previous runs.

https://bugzilla.redhat.com/show_bug.cgi?id=805942
This commit is contained in:
Lennart Poettering 2012-04-13 23:24:47 +02:00
parent 3b6d9a7c50
commit ecedd90fcd
9 changed files with 163 additions and 101 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
TODO
View File

@ -19,8 +19,6 @@ Features:
* cg_create_and_attach() should fail for non-available controllers
* place start-pre/start-post/... scripts in sub cgrouprs
* make gtk-doc optional (like kmod?)
* udev: find a way to tell udev to not cancel firmware requests in initramfs

52
src/core/cgroup.c
View File

@ -108,26 +108,43 @@ void cgroup_bonding_trim_list(CGroupBonding *first, bool delete_root) {
cgroup_bonding_trim(b, delete_root);
}
int cgroup_bonding_install(CGroupBonding *b, pid_t pid) {
int cgroup_bonding_install(CGroupBonding *b, pid_t pid, const char *cgroup_suffix) {
char *p = NULL;
const char *path;
int r;
assert(b);
assert(pid >= 0);
if ((r = cg_create_and_attach(b->controller, b->path, pid)) < 0)
if (cgroup_suffix) {
p = join(b->path, "/", cgroup_suffix, NULL);
if (!p)
return -ENOMEM;
path = p;
} else
path = b->path;
r = cg_create_and_attach(b->controller, path, pid);
free(p);
if (r < 0)
return r;
b->realized = true;
return 0;
}
int cgroup_bonding_install_list(CGroupBonding *first, pid_t pid) {
int cgroup_bonding_install_list(CGroupBonding *first, pid_t pid, const char *cgroup_suffix) {
CGroupBonding *b;
int r;
LIST_FOREACH(by_unit, b, first)
if ((r = cgroup_bonding_install(b, pid)) < 0 && b->essential)
LIST_FOREACH(by_unit, b, first) {
r = cgroup_bonding_install(b, pid, cgroup_suffix);
if (r < 0 && b->essential)
return r;
}
return 0;
}
@ -176,7 +193,11 @@ int cgroup_bonding_set_task_access_list(CGroupBonding *first, mode_t mode, uid_t
return 0;
}
int cgroup_bonding_kill(CGroupBonding *b, int sig, bool sigcont, Set *s) {
int cgroup_bonding_kill(CGroupBonding *b, int sig, bool sigcont, Set *s, const char *cgroup_suffix) {
char *p = NULL;
const char *path;
int r;
assert(b);
assert(sig >= 0);
@ -184,10 +205,22 @@ int cgroup_bonding_kill(CGroupBonding *b, int sig, bool sigcont, Set *s) {
if (!b->ours)
return 0;
return cg_kill_recursive(b->controller, b->path, sig, sigcont, true, false, s);
if (cgroup_suffix) {
p = join(b->path, "/", cgroup_suffix, NULL);
if (!p)
return -ENOMEM;
path = p;
} else
path = b->path;
r = cg_kill_recursive(b->controller, path, sig, sigcont, true, false, s);
free(p);
return r;
}
int cgroup_bonding_kill_list(CGroupBonding *first, int sig, bool sigcont, Set *s) {
int cgroup_bonding_kill_list(CGroupBonding *first, int sig, bool sigcont, Set *s, const char *cgroup_suffix) {
CGroupBonding *b;
Set *allocated_set = NULL;
int ret = -EAGAIN, r;
@ -200,7 +233,8 @@ int cgroup_bonding_kill_list(CGroupBonding *first, int sig, bool sigcont, Set *s
return -ENOMEM;
LIST_FOREACH(by_unit, b, first) {
if ((r = cgroup_bonding_kill(b, sig, sigcont, s)) < 0) {
r = cgroup_bonding_kill(b, sig, sigcont, s, cgroup_suffix);
if (r < 0) {
if (r == -EAGAIN || r == -ESRCH)
continue;

8
src/core/cgroup.h
View File

@ -56,8 +56,8 @@ int cgroup_bonding_realize_list(CGroupBonding *first);
void cgroup_bonding_free(CGroupBonding *b, bool trim);
void cgroup_bonding_free_list(CGroupBonding *first, bool trim);
int cgroup_bonding_install(CGroupBonding *b, pid_t pid);
int cgroup_bonding_install_list(CGroupBonding *first, pid_t pid);
int cgroup_bonding_install(CGroupBonding *b, pid_t pid, const char *suffix);
int cgroup_bonding_install_list(CGroupBonding *first, pid_t pid, const char *suffix);
int cgroup_bonding_set_group_access(CGroupBonding *b, mode_t mode, uid_t uid, gid_t gid);
int cgroup_bonding_set_group_access_list(CGroupBonding *b, mode_t mode, uid_t uid, gid_t gid);
@ -65,8 +65,8 @@ int cgroup_bonding_set_group_access_list(CGroupBonding *b, mode_t mode, uid_t ui
int cgroup_bonding_set_task_access(CGroupBonding *b, mode_t mode, uid_t uid, gid_t gid, int sticky);
int cgroup_bonding_set_task_access_list(CGroupBonding *b, mode_t mode, uid_t uid, gid_t gid, int sticky);
int cgroup_bonding_kill(CGroupBonding *b, int sig, bool sigcont, Set *s);
int cgroup_bonding_kill_list(CGroupBonding *first, int sig, bool sigcont, Set *s);
int cgroup_bonding_kill(CGroupBonding *b, int sig, bool sigcont, Set *s, const char *suffix);
int cgroup_bonding_kill_list(CGroupBonding *first, int sig, bool sigcont, Set *s, const char *suffix);
void cgroup_bonding_trim(CGroupBonding *first, bool delete_root);
void cgroup_bonding_trim_list(CGroupBonding *first, bool delete_root);

5
src/core/execute.c
View File

@ -962,6 +962,7 @@ int exec_spawn(ExecCommand *command,
bool confirm_spawn,
CGroupBonding *cgroup_bondings,
CGroupAttribute *cgroup_attributes,
const char *cgroup_suffix,
pid_t *ret) {
pid_t pid;
@ -1154,7 +1155,7 @@ int exec_spawn(ExecCommand *command,
}
if (cgroup_bondings) {
err = cgroup_bonding_install_list(cgroup_bondings, 0);
err = cgroup_bonding_install_list(cgroup_bondings, 0, cgroup_suffix);
if (err < 0) {
r = EXIT_CGROUP;
goto fail_child;
@ -1505,7 +1506,7 @@ int exec_spawn(ExecCommand *command,
* sure that when we kill the cgroup the process will be
* killed too). */
if (cgroup_bondings)
cgroup_bonding_install_list(cgroup_bondings, pid);
cgroup_bonding_install_list(cgroup_bondings, pid, cgroup_suffix);
log_debug("Forked %s as %lu", command->path, (unsigned long) pid);

1
src/core/execute.h
View File

@ -192,6 +192,7 @@ int exec_spawn(ExecCommand *command,
bool confirm_spawn,
struct CGroupBonding *cgroup_bondings,
struct CGroupAttribute *cgroup_attributes,
const char *cgroup_suffix,
pid_t *ret);
void exec_command_done(ExecCommand *c);

7
src/core/mount.c
View File

@ -805,6 +805,7 @@ static int mount_spawn(Mount *m, ExecCommand *c, pid_t *_pid) {
UNIT(m)->manager->confirm_spawn,
UNIT(m)->cgroup_bondings,
UNIT(m)->cgroup_attributes,
NULL,
&pid)) < 0)
goto fail;
@ -875,7 +876,8 @@ static void mount_enter_signal(Mount *m, MountState state, MountResult f) {
if ((r = set_put(pid_set, LONG_TO_PTR(m->control_pid))) < 0)
goto fail;
if ((r = cgroup_bonding_kill_list(UNIT(m)->cgroup_bondings, sig, true, pid_set)) < 0) {
r = cgroup_bonding_kill_list(UNIT(m)->cgroup_bondings, sig, true, pid_set, NULL);
if (r < 0) {
if (r != -EAGAIN && r != -ESRCH && r != -ENOENT)
log_warning("Failed to kill control group: %s", strerror(-r));
} else if (r > 0)
@ -1833,7 +1835,8 @@ static int mount_kill(Unit *u, KillWho who, KillMode mode, int signo, DBusError
goto finish;
}
if ((q = cgroup_bonding_kill_list(UNIT(m)->cgroup_bondings, signo, false, pid_set)) < 0)
q = cgroup_bonding_kill_list(UNIT(m)->cgroup_bondings, signo, false, pid_set, NULL);
if (q < 0)
if (q != -EAGAIN && q != -ESRCH && q != -ENOENT)
r = q;
}

175
src/core/service.c
View File

@ -1686,6 +1686,7 @@ static int service_spawn(
bool apply_chroot,
bool apply_tty_stdin,
bool set_notify_socket,
bool is_control,
pid_t *_pid) {
pid_t pid;
@ -1767,6 +1768,7 @@ static int service_spawn(
UNIT(s)->manager->confirm_spawn,
UNIT(s)->cgroup_bondings,
UNIT(s)->cgroup_attributes,
is_control ? "control" : NULL,
&pid);
if (r < 0)
@ -1886,15 +1888,17 @@ static void service_enter_stop_post(Service *s, ServiceResult f) {
if ((s->control_command = s->exec_command[SERVICE_EXEC_STOP_POST])) {
s->control_command_id = SERVICE_EXEC_STOP_POST;
if ((r = service_spawn(s,
s->control_command,
true,
false,
!s->permissions_start_only,
!s->root_directory_start_only,
true,
false,
&s->control_pid)) < 0)
r = service_spawn(s,
s->control_command,
true,
false,
!s->permissions_start_only,
!s->root_directory_start_only,
true,
false,
true,
&s->control_pid);
if (r < 0)
goto fail;
@ -1952,7 +1956,8 @@ static void service_enter_signal(Service *s, ServiceState state, ServiceResult f
if ((r = set_put(pid_set, LONG_TO_PTR(s->control_pid))) < 0)
goto fail;
if ((r = cgroup_bonding_kill_list(UNIT(s)->cgroup_bondings, sig, true, pid_set)) < 0) {
r = cgroup_bonding_kill_list(UNIT(s)->cgroup_bondings, sig, true, pid_set, NULL);
if (r < 0) {
if (r != -EAGAIN && r != -ESRCH && r != -ENOENT)
log_warning("Failed to kill control group: %s", strerror(-r));
} else if (r > 0)
@ -2001,15 +2006,17 @@ static void service_enter_stop(Service *s, ServiceResult f) {
if ((s->control_command = s->exec_command[SERVICE_EXEC_STOP])) {
s->control_command_id = SERVICE_EXEC_STOP;
if ((r = service_spawn(s,
s->control_command,
true,
false,
!s->permissions_start_only,
!s->root_directory_start_only,
false,
false,
&s->control_pid)) < 0)
r = service_spawn(s,
s->control_command,
true,
false,
!s->permissions_start_only,
!s->root_directory_start_only,
false,
false,
true,
&s->control_pid);
if (r < 0)
goto fail;
service_set_state(s, SERVICE_STOP);
@ -2054,15 +2061,17 @@ static void service_enter_start_post(Service *s) {
if ((s->control_command = s->exec_command[SERVICE_EXEC_START_POST])) {
s->control_command_id = SERVICE_EXEC_START_POST;
if ((r = service_spawn(s,
s->control_command,
true,
false,
!s->permissions_start_only,
!s->root_directory_start_only,
false,
false,
&s->control_pid)) < 0)
r = service_spawn(s,
s->control_command,
true,
false,
!s->permissions_start_only,
!s->root_directory_start_only,
false,
false,
true,
&s->control_pid);
if (r < 0)
goto fail;
service_set_state(s, SERVICE_START_POST);
@ -2094,7 +2103,7 @@ static void service_enter_start(Service *s) {
/* We want to ensure that nobody leaks processes from
* START_PRE here, so let's go on a killing spree, People
* should not spawn long running processes from START_PRE. */
cgroup_bonding_kill_list(UNIT(s)->cgroup_bondings, SIGKILL, true, NULL);
cgroup_bonding_kill_list(UNIT(s)->cgroup_bondings, SIGKILL, true, NULL, "control");
if (s->type == SERVICE_FORKING) {
s->control_command_id = SERVICE_EXEC_START;
@ -2108,15 +2117,17 @@ static void service_enter_start(Service *s) {
c = s->main_command = s->exec_command[SERVICE_EXEC_START];
}
if ((r = service_spawn(s,
c,
s->type == SERVICE_FORKING || s->type == SERVICE_DBUS || s->type == SERVICE_NOTIFY,
true,
true,
true,
true,
s->notify_access != NOTIFY_NONE,
&pid)) < 0)
r = service_spawn(s,
c,
s->type == SERVICE_FORKING || s->type == SERVICE_DBUS || s->type == SERVICE_NOTIFY,
true,
true,
true,
true,
s->notify_access != NOTIFY_NONE,
false,
&pid);
if (r < 0)
goto fail;
if (s->type == SERVICE_SIMPLE) {
@ -2168,19 +2179,21 @@ static void service_enter_start_pre(Service *s) {
/* Before we start anything, let's clear up what might
* be left from previous runs. */
cgroup_bonding_kill_list(UNIT(s)->cgroup_bondings, SIGKILL, true, NULL);
cgroup_bonding_kill_list(UNIT(s)->cgroup_bondings, SIGKILL, true, NULL, "control");
s->control_command_id = SERVICE_EXEC_START_PRE;
if ((r = service_spawn(s,
s->control_command,
true,
false,
!s->permissions_start_only,
!s->root_directory_start_only,
true,
false,
&s->control_pid)) < 0)
r = service_spawn(s,
s->control_command,
true,
false,
!s->permissions_start_only,
!s->root_directory_start_only,
true,
false,
true,
&s->control_pid);
if (r < 0)
goto fail;
service_set_state(s, SERVICE_START_PRE);
@ -2236,15 +2249,17 @@ static void service_enter_reload(Service *s) {
if ((s->control_command = s->exec_command[SERVICE_EXEC_RELOAD])) {
s->control_command_id = SERVICE_EXEC_RELOAD;
if ((r = service_spawn(s,
s->control_command,
true,
false,
!s->permissions_start_only,
!s->root_directory_start_only,
false,
false,
&s->control_pid)) < 0)
r = service_spawn(s,
s->control_command,
true,
false,
!s->permissions_start_only,
!s->root_directory_start_only,
false,
false,
true,
&s->control_pid);
if (r < 0)
goto fail;
service_set_state(s, SERVICE_RELOAD);
@ -2271,16 +2286,18 @@ static void service_run_next_control(Service *s) {
s->control_command = s->control_command->command_next;
service_unwatch_control_pid(s);
if ((r = service_spawn(s,
s->control_command,
true,
false,
!s->permissions_start_only,
!s->root_directory_start_only,
s->control_command_id == SERVICE_EXEC_START_PRE ||
s->control_command_id == SERVICE_EXEC_STOP_POST,
false,
&s->control_pid)) < 0)
r = service_spawn(s,
s->control_command,
true,
false,
!s->permissions_start_only,
!s->root_directory_start_only,
s->control_command_id == SERVICE_EXEC_START_PRE ||
s->control_command_id == SERVICE_EXEC_STOP_POST,
false,
true,
&s->control_pid);
if (r < 0)
goto fail;
return;
@ -2313,15 +2330,17 @@ static void service_run_next_main(Service *s) {
s->main_command = s->main_command->command_next;
service_unwatch_main_pid(s);
if ((r = service_spawn(s,
s->main_command,
false,
true,
true,
true,
true,
s->notify_access != NOTIFY_NONE,
&pid)) < 0)
r = service_spawn(s,
s->main_command,
false,
true,
true,
true,
true,
s->notify_access != NOTIFY_NONE,
false,
&pid);
if (r < 0)
goto fail;
service_set_main_pid(s, pid);
@ -3647,8 +3666,8 @@ static int service_kill(Unit *u, KillWho who, KillMode mode, int signo, DBusErro
r = q;
goto finish;
}
if ((q = cgroup_bonding_kill_list(UNIT(s)->cgroup_bondings, signo, false, pid_set)) < 0)
q = cgroup_bonding_kill_list(UNIT(s)->cgroup_bondings, signo, false, pid_set, NULL);
if (q < 0)
if (q != -EAGAIN && q != -ESRCH && q != -ENOENT)
r = q;
}

7
src/core/socket.c
View File

@ -1150,6 +1150,7 @@ static int socket_spawn(Socket *s, ExecCommand *c, pid_t *_pid) {
UNIT(s)->manager->confirm_spawn,
UNIT(s)->cgroup_bondings,
UNIT(s)->cgroup_attributes,
NULL,
&pid);
strv_free(argv);
@ -1240,7 +1241,8 @@ static void socket_enter_signal(Socket *s, SocketState state, SocketResult f) {
if ((r = set_put(pid_set, LONG_TO_PTR(s->control_pid))) < 0)
goto fail;
if ((r = cgroup_bonding_kill_list(UNIT(s)->cgroup_bondings, sig, true, pid_set)) < 0) {
r = cgroup_bonding_kill_list(UNIT(s)->cgroup_bondings, sig, true, pid_set, NULL);
if (r < 0) {
if (r != -EAGAIN && r != -ESRCH && r != -ENOENT)
log_warning("Failed to kill control group: %s", strerror(-r));
} else if (r > 0)
@ -2127,7 +2129,8 @@ static int socket_kill(Unit *u, KillWho who, KillMode mode, int signo, DBusError
goto finish;
}
if ((q = cgroup_bonding_kill_list(UNIT(s)->cgroup_bondings, signo, false, pid_set)) < 0)
q = cgroup_bonding_kill_list(UNIT(s)->cgroup_bondings, signo, false, pid_set, NULL);
if (q < 0)
if (q != -EAGAIN && q != -ESRCH && q != -ENOENT)
r = q;
}

7
src/core/swap.c
View File

@ -621,6 +621,7 @@ static int swap_spawn(Swap *s, ExecCommand *c, pid_t *_pid) {
UNIT(s)->manager->confirm_spawn,
UNIT(s)->cgroup_bondings,
UNIT(s)->cgroup_attributes,
NULL,
&pid)) < 0)
goto fail;
@ -690,7 +691,8 @@ static void swap_enter_signal(Swap *s, SwapState state, SwapResult f) {
if ((r = set_put(pid_set, LONG_TO_PTR(s->control_pid))) < 0)
goto fail;
if ((r = cgroup_bonding_kill_list(UNIT(s)->cgroup_bondings, sig, true, pid_set)) < 0) {
r = cgroup_bonding_kill_list(UNIT(s)->cgroup_bondings, sig, true, pid_set, NULL);
if (r < 0) {
if (r != -EAGAIN && r != -ESRCH && r != -ENOENT)
log_warning("Failed to kill control group: %s", strerror(-r));
} else if (r > 0)
@ -1321,7 +1323,8 @@ static int swap_kill(Unit *u, KillWho who, KillMode mode, int signo, DBusError *
goto finish;
}
if ((q = cgroup_bonding_kill_list(UNIT(s)->cgroup_bondings, signo, false, pid_set)) < 0)
q = cgroup_bonding_kill_list(UNIT(s)->cgroup_bondings, signo, false, pid_set, NULL);
if (q < 0)
if (q != -EAGAIN && q != -ESRCH && q != -ENOENT)
r = q;
}