Classify processes from sessions into cgroups

Create a private cgroup tree associated with no controllers, and use it
to map PIDs to sessions.  Since we use our own path structure, remove
internal cgroup-related helpers that interpret the cgroup path structure
to pull out users, slices, and scopes.

3 files changed, 19 insertions, 58 deletions

diff --git a/src/libelogind/sd-bus/bus-creds.c b/src/libelogind/sd-bus/bus-creds.c
index cd1c5e232..aea379d66 100644
--- a/src/libelogind/sd-bus/bus-creds.c
+++ b/src/libelogind/sd-bus/bus-creds.c
@@ -358,8 +358,6 @@ _public_ int sd_bus_creds_get_cgroup(sd_bus_creds *c, const char **ret) {
 }
 
 _public_ int sd_bus_creds_get_unit(sd_bus_creds *c, const char **ret) {
-        int r;
-
         assert_return(c, -EINVAL);
         assert_return(ret, -EINVAL);
 
@@ -368,25 +366,14 @@ _public_ int sd_bus_creds_get_unit(sd_bus_creds *c, const char **ret) {
 
         assert(c->cgroup);
 
-        if (!c->unit) {
-                const char *shifted;
-
-                r = cg_shift_path(c->cgroup, c->cgroup_root, &shifted);
-                if (r < 0)
-                        return r;
-
-                r = cg_path_get_unit(shifted, (char**) &c->unit);
-                if (r < 0)
-                        return r;
-        }
+        if (!c->unit)
+                return -ESRCH;
 
         *ret = c->unit;
         return 0;
 }
 
 _public_ int sd_bus_creds_get_user_unit(sd_bus_creds *c, const char **ret) {
-        int r;
-
         assert_return(c, -EINVAL);
         assert_return(ret, -EINVAL);
 
@@ -395,25 +382,14 @@ _public_ int sd_bus_creds_get_user_unit(sd_bus_creds *c, const char **ret) {
 
         assert(c->cgroup);
 
-        if (!c->user_unit) {
-                const char *shifted;
-
-                r = cg_shift_path(c->cgroup, c->cgroup_root, &shifted);
-                if (r < 0)
-                        return r;
-
-                r = cg_path_get_user_unit(shifted, (char**) &c->user_unit);
-                if (r < 0)
-                        return r;
-        }
+        if (!c->user_unit)
+                return -ESRCH;
 
         *ret = c->user_unit;
         return 0;
 }
 
 _public_ int sd_bus_creds_get_slice(sd_bus_creds *c, const char **ret) {
-        int r;
-
         assert_return(c, -EINVAL);
         assert_return(ret, -EINVAL);
 
@@ -422,17 +398,8 @@ _public_ int sd_bus_creds_get_slice(sd_bus_creds *c, const char **ret) {
 
         assert(c->cgroup);
 
-        if (!c->slice) {
-                const char *shifted;
-
-                r = cg_shift_path(c->cgroup, c->cgroup_root, &shifted);
-                if (r < 0)
-                        return r;
-
-                r = cg_path_get_slice(shifted, (char**) &c->slice);
-                if (r < 0)
-                        return r;
-        }
+        if (!c->slice)
+                return -ESRCH;
 
         *ret = c->slice;
         return 0;
@@ -481,7 +448,7 @@ _public_ int sd_bus_creds_get_owner_uid(sd_bus_creds *c, uid_t *uid) {
         if (r < 0)
                 return r;
 
-        return cg_path_get_owner_uid(shifted, uid);
+        return -ESRCH;
 }
 
 _public_ int sd_bus_creds_get_cmdline(sd_bus_creds *c, char ***cmdline) {
diff --git a/src/libelogind/sd-bus/sd-bus.c b/src/libelogind/sd-bus/sd-bus.c
index 2cb1aafa2..35de5b051 100644
--- a/src/libelogind/sd-bus/sd-bus.c
+++ b/src/libelogind/sd-bus/sd-bus.c
@@ -1124,10 +1124,7 @@ _public_ int sd_bus_open(sd_bus **ret) {
 
         e = secure_getenv("DBUS_STARTER_ADDRESS");
         if (!e) {
-                if (cg_pid_get_owner_uid(0, NULL) >= 0)
-                        return sd_bus_open_user(ret);
-                else
-                        return sd_bus_open_system(ret);
+                return sd_bus_open_system(ret);
         }
 
         r = sd_bus_new(&b);
@@ -3327,10 +3324,7 @@ _public_ int sd_bus_default(sd_bus **ret) {
         /* Finally, if nothing is set use the cached connection for
          * the right scope */
 
-        if (cg_pid_get_owner_uid(0, NULL) >= 0)
-                return sd_bus_default_user(ret);
-        else
-                return sd_bus_default_system(ret);
+        return sd_bus_default_system(ret);
 }
 
 _public_ int sd_bus_get_tid(sd_bus *b, pid_t *tid) {
diff --git a/src/libelogind/sd-login/sd-login.c b/src/libelogind/sd-login/sd-login.c
index cc0677bdf..8e2b7c1dc 100644
--- a/src/libelogind/sd-login/sd-login.c
+++ b/src/libelogind/sd-login/sd-login.c
@@ -46,7 +46,7 @@ _public_ int sd_pid_get_unit(pid_t pid, char **unit) {
         assert_return(pid >= 0, -EINVAL);
         assert_return(unit, -EINVAL);
 
-        return cg_pid_get_unit(pid, unit);
+        return -ESRCH;
 }
 
 _public_ int sd_pid_get_user_unit(pid_t pid, char **unit) {
@@ -54,7 +54,7 @@ _public_ int sd_pid_get_user_unit(pid_t pid, char **unit) {
         assert_return(pid >= 0, -EINVAL);
         assert_return(unit, -EINVAL);
 
-        return cg_pid_get_user_unit(pid, unit);
+        return -ESRCH;
 }
 
 _public_ int sd_pid_get_machine_name(pid_t pid, char **name) {
@@ -62,7 +62,7 @@ _public_ int sd_pid_get_machine_name(pid_t pid, char **name) {
         assert_return(pid >= 0, -EINVAL);
         assert_return(name, -EINVAL);
 
-        return cg_pid_get_machine_name(pid, name);
+        return -ESRCH;
 }
 
 _public_ int sd_pid_get_slice(pid_t pid, char **slice) {
@@ -70,7 +70,7 @@ _public_ int sd_pid_get_slice(pid_t pid, char **slice) {
         assert_return(pid >= 0, -EINVAL);
         assert_return(slice, -EINVAL);
 
-        return cg_pid_get_slice(pid, slice);
+        return -ESRCH;
 }
 
 _public_ int sd_pid_get_owner_uid(pid_t pid, uid_t *uid) {
@@ -78,7 +78,7 @@ _public_ int sd_pid_get_owner_uid(pid_t pid, uid_t *uid) {
         assert_return(pid >= 0, -EINVAL);
         assert_return(uid, -EINVAL);
 
-        return cg_pid_get_owner_uid(pid, uid);
+        return -ESRCH;
 }
 
 _public_ int sd_peer_get_session(int fd, char **session) {
@@ -106,7 +106,7 @@ _public_ int sd_peer_get_owner_uid(int fd, uid_t *uid) {
         if (r < 0)
                 return r;
 
-        return cg_pid_get_owner_uid(ucred.pid, uid);
+        return -ESRCH;
 }
 
 _public_ int sd_peer_get_unit(int fd, char **unit) {
@@ -120,7 +120,7 @@ _public_ int sd_peer_get_unit(int fd, char **unit) {
         if (r < 0)
                 return r;
 
-        return cg_pid_get_unit(ucred.pid, unit);
+        return -ESRCH;
 }
 
 _public_ int sd_peer_get_user_unit(int fd, char **unit) {
@@ -134,7 +134,7 @@ _public_ int sd_peer_get_user_unit(int fd, char **unit) {
         if (r < 0)
                 return r;
 
-        return cg_pid_get_user_unit(ucred.pid, unit);
+        return -ESRCH;
 }
 
 _public_ int sd_peer_get_machine_name(int fd, char **machine) {
@@ -148,7 +148,7 @@ _public_ int sd_peer_get_machine_name(int fd, char **machine) {
         if (r < 0)
                 return r;
 
-        return cg_pid_get_machine_name(ucred.pid, machine);
+        return -ESRCH;
 }
 
 _public_ int sd_peer_get_slice(int fd, char **slice) {
@@ -162,7 +162,7 @@ _public_ int sd_peer_get_slice(int fd, char **slice) {
         if (r < 0)
                 return r;
 
-        return cg_pid_get_slice(ucred.pid, slice);
+        return -ESRCH;
 }
 
 static int file_of_uid(uid_t uid, char **p) {