daandemeyer / rpms / systemd

Forked from rpms/systemd 2 years ago
Clone
Blob Blame History Raw
From 80753fa3c0622fd8117c64e1ed2d7841edee3b00 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Thu, 13 Nov 2014 14:34:42 +0100
Subject: [PATCH] core: introduce new Delegate=yes/no property controlling
 creation of cgroup subhierarchies

For priviliged units this resource control property ensures that the
processes have all controllers systemd manages enabled.

For unpriviliged services (those with User= set) this ensures that
access rights to the service cgroup is granted to the user in question,
to create further subgroups. Note that this only applies to the
name=systemd hierarchy though, as access to other controllers is not
safe for unpriviliged processes.

Delegate=yes should be set for container scopes where a systemd instance
inside the container shall manage the hierarchies below its own cgroup
and have access to all controllers.

Delegate=yes should also be set for user@.service, so that systemd
--user can run, controlling its own cgroup tree.

This commit changes machined, systemd-nspawn@.service and user@.service
to set this boolean, in order to ensure that container management will
just work, and the user systemd instance can run fine.

(cherry picked from a931ad47a8623163a29d898224d8a8c1177ffdaf)

Resolves: #1179715
---
 man/systemd.resource-control.xml      | 14 ++++++++++++
 src/core/cgroup.c                     | 19 +++++++++++++++--
 src/core/cgroup.h                     |  2 ++
 src/core/dbus-cgroup.c                | 40 +++++++++++++++++++++++++++++++++++
 src/core/execute.c                    | 23 +++++++++++++++++---
 src/core/execute.h                    |  2 ++
 src/core/load-fragment-gperf.gperf.m4 |  3 ++-
 src/core/mount.c                      |  1 +
 src/core/service.c                    |  1 +
 src/core/socket.c                     |  1 +
 src/core/swap.c                       |  1 +
 src/machine/machined-dbus.c           | 10 +++++++++
 src/shared/cgroup-util.h              |  3 ++-
 units/systemd-nspawn@.service.in      |  1 +
 14 files changed, 114 insertions(+), 7 deletions(-)

diff --git a/man/systemd.resource-control.xml b/man/systemd.resource-control.xml
index 8688905..3748c0c 100644
--- a/man/systemd.resource-control.xml
+++ b/man/systemd.resource-control.xml
@@ -327,6 +327,20 @@ along with systemd; If not, see <http://www.gnu.org/licenses/>.
         </listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><varname>Delegate=</varname></term>
+
+        <listitem>
+          <para>Turns on delegation of further resource control
+          partitioning to processes of the unit. For unpriviliged
+          services (i.e. those using the <varname>User=</varname>
+          setting) this allows processes to create a subhierarchy
+          beneath its control group path. For priviliged services and
+          scopes this ensures the processes will have all control
+          group controllers enabled.</para>
+        </listitem>
+      </varlistentry>
+
     </variablelist>
   </refsect1>
 
diff --git a/src/core/cgroup.c b/src/core/cgroup.c
index 32e2599..764311f 100644
--- a/src/core/cgroup.c
+++ b/src/core/cgroup.c
@@ -94,14 +94,16 @@ void cgroup_context_dump(CGroupContext *c, FILE* f, const char *prefix) {
                 "%sCPUShares=%lu\n"
                 "%sBlockIOWeight=%lu\n"
                 "%sMemoryLimit=%" PRIu64 "\n"
-                "%sDevicePolicy=%s\n",
+                "%sDevicePolicy=%s\n"
+                "%sDelegate=%s\n",
                 prefix, yes_no(c->cpu_accounting),
                 prefix, yes_no(c->blockio_accounting),
                 prefix, yes_no(c->memory_accounting),
                 prefix, c->cpu_shares,
                 prefix, c->blockio_weight,
                 prefix, c->memory_limit,
-                prefix, cgroup_device_policy_to_string(c->device_policy));
+                prefix, cgroup_device_policy_to_string(c->device_policy),
+                prefix, yes_no(c->delegate));
 
         LIST_FOREACH(device_allow, a, c->device_allow)
                 fprintf(f,
@@ -342,6 +344,19 @@ static CGroupControllerMask unit_get_cgroup_mask(Unit *u) {
         if (!c)
                 return 0;
 
+        /* If delegation is turned on, then turn on all cgroups,
+         * unless the process we fork into it is known to drop
+         * privileges anyway, and shouldn't get access to the
+         * controllers anyway. */
+
+        if (c->delegate) {
+                ExecContext *e;
+
+                e = unit_get_exec_context(u);
+                if (!e || exec_context_maintains_privileges(e))
+                        return _CGROUP_CONTROLLER_MASK_ALL;
+        }
+
         return cgroup_context_get_mask(c);
 }
 
diff --git a/src/core/cgroup.h b/src/core/cgroup.h
index 0a079e9..d00bcac 100644
--- a/src/core/cgroup.h
+++ b/src/core/cgroup.h
@@ -80,6 +80,8 @@ struct CGroupContext {
 
         CGroupDevicePolicy device_policy;
         LIST_HEAD(CGroupDeviceAllow, device_allow);
+
+        bool delegate;
 };
 
 #include "unit.h"
diff --git a/src/core/dbus-cgroup.c b/src/core/dbus-cgroup.c
index 9ebcad9..a13c869 100644
--- a/src/core/dbus-cgroup.c
+++ b/src/core/dbus-cgroup.c
@@ -124,6 +124,7 @@ static int bus_cgroup_append_device_allow(DBusMessageIter *i, const char *proper
 }
 
 const BusProperty bus_cgroup_context_properties[] = {
+        { "Delegate",                bus_property_append_bool,            "b",     offsetof(CGroupContext, delegate)           },
         { "CPUAccounting",           bus_property_append_bool,            "b",     offsetof(CGroupContext, cpu_accounting)     },
         { "CPUShares",               bus_property_append_ul,              "t",     offsetof(CGroupContext, cpu_shares)         },
         { "BlockIOAccounting",       bus_property_append_bool,            "b",     offsetof(CGroupContext, blockio_accounting) },
@@ -138,6 +139,38 @@ const BusProperty bus_cgroup_context_properties[] = {
         {}
 };
 
+static int bus_cgroup_set_transient_property(
+                Unit *u,
+                CGroupContext *c,
+                const char *name,
+                DBusMessageIter *i,
+                UnitSetPropertiesMode mode,
+                DBusError *error) {
+
+        assert(u);
+        assert(c);
+        assert(name);
+        assert(i);
+
+        if (streq(name, "Delegate")) {
+
+                if (dbus_message_iter_get_arg_type(i) != DBUS_TYPE_BOOLEAN)
+                        return -EINVAL;
+
+                if (mode != UNIT_CHECK) {
+                        dbus_bool_t b;
+
+                        dbus_message_iter_get_basic(i, &b);
+                        c->delegate = b;
+                        unit_write_drop_in_private(u, mode, name, b ? "Delegate=yes" : "Delegate=no");
+                }
+
+                return 1;
+        }
+
+        return 0;
+}
+
 int bus_cgroup_set_property(
                 Unit *u,
                 CGroupContext *c,
@@ -550,5 +583,12 @@ int bus_cgroup_set_property(
                 return 1;
         }
 
+        if (u->transient && u->load_state == UNIT_STUB) {
+                int r;
+                r = bus_cgroup_set_transient_property(u, c, name, i, mode, error);
+                if (r != 0)
+                        return r;
+        }
+
         return 0;
 }
diff --git a/src/core/execute.c b/src/core/execute.c
index 981b9e4..c3fd6a8 100644
--- a/src/core/execute.c
+++ b/src/core/execute.c
@@ -1035,6 +1035,7 @@ int exec_spawn(ExecCommand *command,
                bool confirm_spawn,
                CGroupControllerMask cgroup_supported,
                const char *cgroup_path,
+               bool cgroup_delegate,
                const char *unit_id,
                int idle_pipe[4],
                pid_t *ret) {
@@ -1299,8 +1300,10 @@ int exec_spawn(ExecCommand *command,
                         }
                 }
 
-#ifdef HAVE_PAM
-                if (cgroup_path && context->user && context->pam_name) {
+                /* If delegation is enabled we'll pass ownership of the cgroup
+                 * (but only in systemd's own controller hierarchy!) to the
+                 * user of the new process. */
+               if (cgroup_path && context->user && cgroup_delegate) {
                         err = cg_set_task_access(SYSTEMD_CGROUP_CONTROLLER, cgroup_path, 0644, uid, gid);
                         if (err < 0) {
                                 r = EXIT_CGROUP;
@@ -1314,7 +1317,6 @@ int exec_spawn(ExecCommand *command,
                                 goto fail_child;
                         }
                 }
-#endif
 
                 if (apply_permissions) {
                         err = enforce_groups(context, username, gid);
@@ -2069,6 +2071,21 @@ void exec_context_dump(ExecContext *c, FILE* f, const char *prefix) {
                         prefix, c->utmp_id);
 }
 
+bool exec_context_maintains_privileges(ExecContext *c) {
+        assert(c);
+
+        /* Returns true if the process forked off would run under
+         * an unchanged UID or as root. */
+
+        if (!c->user)
+                return true;
+
+        if (streq(c->user, "root") || streq(c->user, "0"))
+                return true;
+
+        return false;
+}
+
 void exec_status_start(ExecStatus *s, pid_t pid) {
         assert(s);
 
diff --git a/src/core/execute.h b/src/core/execute.h
index c1e9717..eca9d7d 100644
--- a/src/core/execute.h
+++ b/src/core/execute.h
@@ -173,6 +173,7 @@ int exec_spawn(ExecCommand *command,
                bool confirm_spawn,
                CGroupControllerMask cgroup_mask,
                const char *cgroup_path,
+               bool cgroup_delegate,
                const char *unit_id,
                int pipe_fd[2],
                pid_t *ret);
@@ -199,6 +200,7 @@ void exec_context_tty_reset(const ExecContext *context);
 int exec_context_load_environment(const ExecContext *c, char ***l);
 
 bool exec_context_may_touch_console(ExecContext *c);
+bool exec_context_maintains_privileges(ExecContext *c);
 void exec_context_serialize(const ExecContext *c, Unit *u, FILE *f);
 
 void exec_status_start(ExecStatus *s, pid_t pid);
diff --git a/src/core/load-fragment-gperf.gperf.m4 b/src/core/load-fragment-gperf.gperf.m4
index 0991cb9..3e88c8a 100644
--- a/src/core/load-fragment-gperf.gperf.m4
+++ b/src/core/load-fragment-gperf.gperf.m4
@@ -95,7 +95,8 @@ $1.BlockIOAccounting,            config_parse_bool,                  0,
 $1.BlockIOWeight,                config_parse_blockio_weight,        0,                             offsetof($1, cgroup_context)
 $1.BlockIODeviceWeight,          config_parse_blockio_device_weight, 0,                             offsetof($1, cgroup_context)
 $1.BlockIOReadBandwidth,         config_parse_blockio_bandwidth,     0,                             offsetof($1, cgroup_context)
-$1.BlockIOWriteBandwidth,        config_parse_blockio_bandwidth,     0,                             offsetof($1, cgroup_context)'
+$1.BlockIOWriteBandwidth,        config_parse_blockio_bandwidth,     0,                             offsetof($1, cgroup_context)
+$1.Delegate,                     config_parse_bool,                  0,                             offsetof($1, cgroup_context.delegate)'
 )m4_dnl
 Unit.Description,                config_parse_unit_string_printf,    0,                             offsetof(Unit, description)
 Unit.Documentation,              config_parse_documentation,         0,                             offsetof(Unit, documentation)
diff --git a/src/core/mount.c b/src/core/mount.c
index 3672338..f7c98c4 100644
--- a/src/core/mount.c
+++ b/src/core/mount.c
@@ -793,6 +793,7 @@ static int mount_spawn(Mount *m, ExecCommand *c, pid_t *_pid) {
                        UNIT(m)->manager->confirm_spawn,
                        UNIT(m)->manager->cgroup_supported,
                        UNIT(m)->cgroup_path,
+                       m->cgroup_context.delegate,
                        UNIT(m)->id,
                        NULL,
                        &pid);
diff --git a/src/core/service.c b/src/core/service.c
index f6fdbbc..da30d77 100644
--- a/src/core/service.c
+++ b/src/core/service.c
@@ -1869,6 +1869,7 @@ static int service_spawn(
                        UNIT(s)->manager->confirm_spawn,
                        UNIT(s)->manager->cgroup_supported,
                        path,
+                       s->cgroup_context.delegate,
                        UNIT(s)->id,
                        s->type == SERVICE_IDLE ? UNIT(s)->manager->idle_pipe : NULL,
                        &pid);
diff --git a/src/core/socket.c b/src/core/socket.c
index 32e0d35..f365125 100644
--- a/src/core/socket.c
+++ b/src/core/socket.c
@@ -1229,6 +1229,7 @@ static int socket_spawn(Socket *s, ExecCommand *c, pid_t *_pid) {
                        UNIT(s)->manager->confirm_spawn,
                        UNIT(s)->manager->cgroup_supported,
                        UNIT(s)->cgroup_path,
+                       s->cgroup_context.delegate,
                        UNIT(s)->id,
                        NULL,
                        &pid);
diff --git a/src/core/swap.c b/src/core/swap.c
index 727bb95..597c8ca 100644
--- a/src/core/swap.c
+++ b/src/core/swap.c
@@ -591,6 +591,7 @@ static int swap_spawn(Swap *s, ExecCommand *c, pid_t *_pid) {
                        UNIT(s)->manager->confirm_spawn,
                        UNIT(s)->manager->cgroup_supported,
                        UNIT(s)->cgroup_path,
+                       s->cgroup_context.delegate,
                        UNIT(s)->id,
                        NULL,
                        &pid);
diff --git a/src/machine/machined-dbus.c b/src/machine/machined-dbus.c
index 22caadf..0cebdc5 100644
--- a/src/machine/machined-dbus.c
+++ b/src/machine/machined-dbus.c
@@ -739,9 +739,11 @@ int manager_start_scope(
         DBusMessageIter iter, sub, sub2, sub3, sub4;
         const char *timeout_stop_property = "TimeoutStopUSec";
         const char *pids_property = "PIDs";
+        const char *delegate_property = "Delegate";
         uint64_t timeout = 500 * USEC_PER_MSEC;
         const char *fail = "fail";
         uint32_t u;
+        dbus_bool_t b = 1;
         int r;
 
         assert(manager);
@@ -814,6 +816,14 @@ int manager_start_scope(
             !dbus_message_iter_close_container(&sub, &sub2))
                 return log_oom();
 
+        if (!dbus_message_iter_open_container(&sub, DBUS_TYPE_STRUCT, NULL, &sub2) ||
+            !dbus_message_iter_append_basic(&sub2, DBUS_TYPE_STRING, &delegate_property) ||
+            !dbus_message_iter_open_container(&sub2, DBUS_TYPE_VARIANT, "b", &sub3) ||
+            !dbus_message_iter_append_basic(&sub3, DBUS_TYPE_BOOLEAN, &b) ||
+            !dbus_message_iter_close_container(&sub2, &sub3) ||
+            !dbus_message_iter_close_container(&sub, &sub2))
+                return log_oom();
+
         if (more_properties) {
                 r = copy_many_fields(&sub, more_properties);
                 if (r < 0)
diff --git a/src/shared/cgroup-util.h b/src/shared/cgroup-util.h
index 0963450..0608b9a 100644
--- a/src/shared/cgroup-util.h
+++ b/src/shared/cgroup-util.h
@@ -34,7 +34,8 @@ typedef enum CGroupControllerMask {
         CGROUP_CPUACCT = 2,
         CGROUP_BLKIO = 4,
         CGROUP_MEMORY = 8,
-        CGROUP_DEVICE = 16
+        CGROUP_DEVICE = 16,
+        _CGROUP_CONTROLLER_MASK_ALL = 31
 } CGroupControllerMask;
 
 /*
diff --git a/units/systemd-nspawn@.service.in b/units/systemd-nspawn@.service.in
index 8e00736..bdfa89f 100644
--- a/units/systemd-nspawn@.service.in
+++ b/units/systemd-nspawn@.service.in
@@ -12,6 +12,7 @@ Documentation=man:systemd-nspawn(1)
 [Service]
 ExecStart=@bindir@/systemd-nspawn -bjD /var/lib/container/%i
 Type=notify
+Delegate=yes
 
 [Install]
 WantedBy=multi-user.target