login: track login class (i.e. one of "user", "greeter", "lock-screen") for each session

This introduces the new PAM environment variable XDG_SESSION_CLASS. If
not set, defaults to "user".

This is useful for apps that want to distuingish real user logins from
"fake" ones which just exist to show a gdm login screen or a lock
screen.

6 files changed, 76 insertions, 5 deletions

diff --git a/src/login/loginctl.c b/src/login/loginctl.c
index 7e0056c589..30e97e352a 100644
--- a/src/login/loginctl.c
+++ b/src/login/loginctl.c
@@ -349,6 +349,7 @@ typedef struct SessionStatusInfo {
         const char *service;
         pid_t leader;
         const char *type;
+        const char *class;
         bool active;
 } SessionStatusInfo;
 
@@ -431,10 +432,19 @@ static void print_session_status_info(SessionStatusInfo *i) {
                 if (i->type)
                         printf("; type %s", i->type);
 
+                if (i->class)
+                        printf("; class %s", i->class);
+
                 printf("\n");
-        } else if (i->type)
+        } else if (i->type) {
                 printf("\t    Type: %s\n", i->type);
 
+                if (i->class)
+                        printf("; class %s", i->class);
+        } else if (i->class)
+                printf("\t   Class: %s\n", i->class);
+
+
         printf("\t  Active: %s\n", yes_no(i->active));
 
         if (i->control_group) {
@@ -571,6 +581,8 @@ static int status_property_session(const char *name, DBusMessageIter *iter, Sess
                                 i->service = s;
                         else if (streq(name, "Type"))
                                 i->type = s;
+                        else if (streq(name, "Class"))
+                                i->class = s;
                 }
                 break;
         }
diff --git a/src/login/logind-dbus.c b/src/login/logind-dbus.c
index 7794ab917e..d8f4d89474 100644
--- a/src/login/logind-dbus.c
+++ b/src/login/logind-dbus.c
@@ -62,6 +62,7 @@
         "   <arg name=\"leader\" type=\"u\" direction=\"in\"/>\n"       \
         "   <arg name=\"sevice\" type=\"s\" direction=\"in\"/>\n"       \
         "   <arg name=\"type\" type=\"s\" direction=\"in\"/>\n"         \
+        "   <arg name=\"class\" type=\"s\" direction=\"in\"/>\n"        \
         "   <arg name=\"seat\" type=\"s\" direction=\"in\"/>\n"         \
         "   <arg name=\"vtnr\" type=\"u\" direction=\"in\"/>\n"         \
         "   <arg name=\"tty\" type=\"s\" direction=\"in\"/>\n"          \
@@ -222,11 +223,12 @@ static int bus_manager_append_idle_hint_since(DBusMessageIter *i, const char *pr
 static int bus_manager_create_session(Manager *m, DBusMessage *message, DBusMessage **_reply) {
         Session *session = NULL;
         User *user = NULL;
-        const char *type, *seat, *tty, *display, *remote_user, *remote_host, *service;
+        const char *type, *class, *seat, *tty, *display, *remote_user, *remote_host, *service;
         uint32_t uid, leader, audit_id = 0;
         dbus_bool_t remote, kill_processes;
         char **controllers = NULL, **reset_controllers = NULL;
         SessionType t;
+        SessionClass c;
         Seat *s;
         DBusMessageIter iter;
         int r;
@@ -271,6 +273,17 @@ static int bus_manager_create_session(Manager *m, DBusMessage *message, DBusMess
             dbus_message_iter_get_arg_type(&iter) != DBUS_TYPE_STRING)
                 return -EINVAL;
 
+        dbus_message_iter_get_basic(&iter, &class);
+        if (isempty(class))
+                c = SESSION_USER;
+        else
+                c = session_class_from_string(class);
+
+        if (c < 0 ||
+            !dbus_message_iter_next(&iter) ||
+            dbus_message_iter_get_arg_type(&iter) != DBUS_TYPE_STRING)
+                return -EINVAL;
+
         dbus_message_iter_get_basic(&iter, &seat);
 
         if (isempty(seat))
@@ -467,6 +480,7 @@ static int bus_manager_create_session(Manager *m, DBusMessage *message, DBusMess
         session->leader = leader;
         session->audit_id = audit_id;
         session->type = t;
+        session->class = c;
         session->remote = remote;
         session->controllers = controllers;
         session->reset_controllers = reset_controllers;
diff --git a/src/login/logind-session-dbus.c b/src/login/logind-session-dbus.c
index 9767f7d30c..102f8ac99b 100644
--- a/src/login/logind-session-dbus.c
+++ b/src/login/logind-session-dbus.c
@@ -57,6 +57,7 @@
         "  <property name=\"Leader\" type=\"u\" access=\"read\"/>\n"    \
         "  <property name=\"Audit\" type=\"u\" access=\"read\"/>\n"     \
         "  <property name=\"Type\" type=\"s\" access=\"read\"/>\n"      \
+        "  <property name=\"Class\" type=\"s\" access=\"read\"/>\n"      \
         "  <property name=\"Active\" type=\"b\" access=\"read\"/>\n"    \
         "  <property name=\"Controllers\" type=\"as\" access=\"read\"/>\n" \
         "  <property name=\"ResetControllers\" type=\"as\" access=\"read\"/>\n" \
@@ -196,6 +197,7 @@ static int bus_session_append_idle_hint_since(DBusMessageIter *i, const char *pr
 }
 
 static DEFINE_BUS_PROPERTY_APPEND_ENUM(bus_session_append_type, session_type, SessionType);
+static DEFINE_BUS_PROPERTY_APPEND_ENUM(bus_session_append_class, session_class, SessionClass);
 
 static int get_session_for_path(Manager *m, const char *path, Session **_s) {
         Session *s;
@@ -238,6 +240,7 @@ static const BusProperty bus_login_session_properties[] = {
         { "Leader",                 bus_property_append_pid,            "u", offsetof(Session, leader)              },
         { "Audit",                  bus_property_append_uint32,         "u", offsetof(Session, audit_id)            },
         { "Type",                   bus_session_append_type,            "s", offsetof(Session, type)                },
+        { "Class",                  bus_session_append_class,           "s", offsetof(Session, class)               },
         { "Active",                 bus_session_append_active,          "b", 0 },
         { "Controllers",            bus_property_append_strv,          "as", offsetof(Session, controllers),        true },
         { "ResetControllers",       bus_property_append_strv,          "as", offsetof(Session, reset_controllers),  true },
diff --git a/src/login/logind-session.c b/src/login/logind-session.c
index c0d9532968..af9c12dcd5 100644
--- a/src/login/logind-session.c
+++ b/src/login/logind-session.c
@@ -145,6 +145,11 @@ int session_save(Session *s) {
                         "TYPE=%s\n",
                         session_type_to_string(s->type));
 
+        if (s->class >= 0)
+                fprintf(f,
+                        "CLASS=%s\n",
+                        session_class_to_string(s->class));
+
         if (s->cgroup_path)
                 fprintf(f,
                         "CGROUP=%s\n",
@@ -225,7 +230,8 @@ int session_load(Session *s) {
                 *vtnr = NULL,
                 *leader = NULL,
                 *audit_id = NULL,
-                *type = NULL;
+                *type = NULL,
+                *class = NULL;
 
         int k, r;
 
@@ -245,6 +251,7 @@ int session_load(Session *s) {
                            "VTNR",           &vtnr,
                            "LEADER",         &leader,
                            "TYPE",           &type,
+                           "CLASS",          &class,
                            NULL);
 
         if (r < 0)
@@ -297,6 +304,14 @@ int session_load(Session *s) {
                         s->type = t;
         }
 
+        if (class) {
+                SessionClass c;
+
+                c = session_class_from_string(class);
+                if (c >= 0)
+                        s->class = c;
+        }
+
         if (s->fifo_path) {
                 int fd;
 
@@ -947,6 +962,14 @@ static const char* const session_type_table[_SESSION_TYPE_MAX] = {
 
 DEFINE_STRING_TABLE_LOOKUP(session_type, SessionType);
 
+static const char* const session_class_table[_SESSION_CLASS_MAX] = {
+        [SESSION_USER] = "user",
+        [SESSION_GREETER] = "greeter",
+        [SESSION_LOCK_SCREEN] = "lock-screen"
+};
+
+DEFINE_STRING_TABLE_LOOKUP(session_class, SessionClass);
+
 static const char* const kill_who_table[_KILL_WHO_MAX] = {
         [KILL_LEADER] = "leader",
         [KILL_ALL] = "all"
diff --git a/src/login/logind-session.h b/src/login/logind-session.h
index 8e394ac0d8..d0b8c87fab 100644
--- a/src/login/logind-session.h
+++ b/src/login/logind-session.h
@@ -38,6 +38,14 @@ typedef enum SessionType {
         _SESSION_TYPE_INVALID = -1
 } SessionType;
 
+typedef enum SessionClass {
+        SESSION_USER,
+        SESSION_GREETER,
+        SESSION_LOCK_SCREEN,
+        _SESSION_CLASS_MAX,
+        _SESSION_CLASS_INVALID = -1
+} SessionClass;
+
 typedef enum KillWho {
         KILL_LEADER,
         KILL_ALL,
@@ -50,6 +58,7 @@ struct Session {
 
         char *id;
         SessionType type;
+        SessionClass class;
 
         char *state_file;
 
@@ -118,6 +127,9 @@ int session_send_lock(Session *s, bool lock);
 const char* session_type_to_string(SessionType t);
 SessionType session_type_from_string(const char *s);
 
+const char* session_class_to_string(SessionClass t);
+SessionClass session_class_from_string(const char *s);
+
 const char *kill_who_to_string(KillWho k);
 KillWho kill_who_from_string(const char *s);
 
diff --git a/src/login/pam-module.c b/src/login/pam-module.c
index 46509245fb..8544413a08 100644
--- a/src/login/pam-module.c
+++ b/src/login/pam-module.c
@@ -321,7 +321,7 @@ _public_ PAM_EXTERN int pam_sm_open_session(
 
         struct passwd *pw;
         bool kill_processes = false, debug = false;
-        const char *username, *id, *object_path, *runtime_path, *service = NULL, *tty = NULL, *display = NULL, *remote_user = NULL, *remote_host = NULL, *seat = NULL, *type, *cvtnr = NULL;
+        const char *username, *id, *object_path, *runtime_path, *service = NULL, *tty = NULL, *display = NULL, *remote_user = NULL, *remote_host = NULL, *seat = NULL, *type, *class, *cvtnr = NULL;
         char **controllers = NULL, **reset_controllers = NULL, **kill_only_users = NULL, **kill_exclude_users = NULL;
         DBusError error;
         uint32_t uid, pid;
@@ -465,13 +465,20 @@ _public_ PAM_EXTERN int pam_sm_open_session(
         type = !isempty(display) ? "x11" :
                    !isempty(tty) ? "tty" : "unspecified";
 
-        remote = !isempty(remote_host) && !streq(remote_host, "localhost") && !streq(remote_host, "localhost.localdomain");
+        class = pam_getenv(handle, "XDG_SESSION_CLASS");
+        if (isempty(class))
+                class = "user";
+
+        remote = !isempty(remote_host) &&
+                !streq(remote_host, "localhost") &&
+                !streq(remote_host, "localhost.localdomain");
 
         if (!dbus_message_append_args(m,
                                       DBUS_TYPE_UINT32, &uid,
                                       DBUS_TYPE_UINT32, &pid,
                                       DBUS_TYPE_STRING, &service,
                                       DBUS_TYPE_STRING, &type,
+                                      DBUS_TYPE_STRING, &class,
                                       DBUS_TYPE_STRING, &seat,
                                       DBUS_TYPE_UINT32, &vtnr,
                                       DBUS_TYPE_STRING, &tty,