sd-bus: properly handle creds that are known but undefined for a process

A number of fields do not apply to all processes, including: there a
processes without a controlling tty, without parent process, without
service, user services or session. To distuingish these cases from the
case where we simply don't have the data, always return ENXIO for them,
while returning ENODATA for the case where we really lack the
information.

Also update the credentials dumping code to show this properly. Fields
that are known but do not apply are now shown as "n/a".

Note that this also changes some of the calls in process-util.c and
cgroup-util.c to return ENXIO for these cases.

10 files changed, 211 insertions, 102 deletions

diff --git a/src/libsystemd/sd-bus/bus-control.c b/src/libsystemd/sd-bus/bus-control.c
index ca31807f70..fa4c28174d 100644
--- a/src/libsystemd/sd-bus/bus-control.c
+++ b/src/libsystemd/sd-bus/bus-control.c
@@ -423,9 +423,24 @@ static int bus_populate_creds_from_items(
                                 c->mask |= SD_BUS_CREDS_TID;
                         }
 
-                        if (mask & SD_BUS_CREDS_PPID && item->pids.ppid > 0) {
-                                c->ppid = (pid_t) item->pids.ppid;
-                                c->mask |= SD_BUS_CREDS_PPID;
+                        if (mask & SD_BUS_CREDS_PPID) {
+                                if (item->pids.ppid > 0) {
+                                        c->ppid = (pid_t) item->pids.ppid;
+                                        c->mask |= SD_BUS_CREDS_PPID;
+                                } else if (item->pids.pid == 1) {
+                                        /* The structure doesn't
+                                         * really distuingish the case
+                                         * where a process has no
+                                         * parent and where we don't
+                                         * know it because it could
+                                         * not be translated due to
+                                         * namespaces. However, we
+                                         * know that PID 1 has no
+                                         * parent process, hence let's
+                                         * patch that in, manually. */
+                                        c->ppid = 0;
+                                        c->mask |= SD_BUS_CREDS_PPID;
+                                }
                         }
 
                         break;
@@ -565,12 +580,12 @@ static int bus_populate_creds_from_items(
                         break;
 
                 case KDBUS_ITEM_AUDIT:
-                        if (mask & SD_BUS_CREDS_AUDIT_SESSION_ID && (uint32_t) item->audit.sessionid != (uint32_t) -1) {
+                        if (mask & SD_BUS_CREDS_AUDIT_SESSION_ID) {
                                 c->audit_session_id = (uint32_t) item->audit.sessionid;
                                 c->mask |= SD_BUS_CREDS_AUDIT_SESSION_ID;
                         }
 
-                        if (mask & SD_BUS_CREDS_AUDIT_LOGIN_UID && (uid_t) item->audit.loginuid != UID_INVALID) {
+                        if (mask & SD_BUS_CREDS_AUDIT_LOGIN_UID) {
                                 c->audit_login_uid = (uid_t) item->audit.loginuid;
                                 c->mask |= SD_BUS_CREDS_AUDIT_LOGIN_UID;
                         }
diff --git a/src/libsystemd/sd-bus/bus-creds.c b/src/libsystemd/sd-bus/bus-creds.c
index 8d02885d3b..ed9bf5293b 100644
--- a/src/libsystemd/sd-bus/bus-creds.c
+++ b/src/libsystemd/sd-bus/bus-creds.c
@@ -302,6 +302,12 @@ _public_ int sd_bus_creds_get_ppid(sd_bus_creds *c, pid_t *ppid) {
         if (!(c->mask & SD_BUS_CREDS_PPID))
                 return -ENODATA;
 
+        /* PID 1 has no parent process. Let's distuingish the case of
+         * not knowing and not having a parent process by the returned
+         * error code. */
+        if (c->ppid == 0)
+                return -ENXIO;
+
         *ppid = c->ppid;
         return 0;
 }
@@ -360,7 +366,9 @@ _public_ int sd_bus_creds_get_exe(sd_bus_creds *c, const char **ret) {
         if (!(c->mask & SD_BUS_CREDS_EXE))
                 return -ENODATA;
 
-        assert(c->exe);
+        if (!c->exe)
+                return -ENXIO;
+
         *ret = c->exe;
         return 0;
 }
@@ -510,8 +518,8 @@ _public_ int sd_bus_creds_get_cmdline(sd_bus_creds *c, char ***cmdline) {
         if (!(c->mask & SD_BUS_CREDS_CMDLINE))
                 return -ENODATA;
 
-        assert_return(c->cmdline, -ESRCH);
-        assert(c->cmdline);
+        if (!c->cmdline)
+                return -ENXIO;
 
         if (!c->cmdline_array) {
                 c->cmdline_array = strv_parse_nulstr(c->cmdline, c->cmdline_size);
@@ -530,6 +538,9 @@ _public_ int sd_bus_creds_get_audit_session_id(sd_bus_creds *c, uint32_t *sessio
         if (!(c->mask & SD_BUS_CREDS_AUDIT_SESSION_ID))
                 return -ENODATA;
 
+        if (c->audit_session_id == AUDIT_SESSION_INVALID)
+                return -ENXIO;
+
         *sessionid = c->audit_session_id;
         return 0;
 }
@@ -541,6 +552,9 @@ _public_ int sd_bus_creds_get_audit_login_uid(sd_bus_creds *c, uid_t *uid) {
         if (!(c->mask & SD_BUS_CREDS_AUDIT_LOGIN_UID))
                 return -ENODATA;
 
+        if (c->audit_login_uid == UID_INVALID)
+                return -ENXIO;
+
         *uid = c->audit_login_uid;
         return 0;
 }
@@ -552,6 +566,9 @@ _public_ int sd_bus_creds_get_tty(sd_bus_creds *c, const char **ret) {
         if (!(c->mask & SD_BUS_CREDS_TTY))
                 return -ENODATA;
 
+        if (!c->tty)
+                return -ENXIO;
+
         *ret = c->tty;
         return 0;
 }
@@ -787,8 +804,10 @@ int bus_creds_add_more(sd_bus_creds *c, uint64_t mask, pid_t pid, pid_t tid) {
                                                         if (r < 0)
                                                                 return r;
 
-                                                        c->mask |= SD_BUS_CREDS_PPID;
-                                                }
+                                                } else
+                                                        c->ppid = 0;
+
+                                                c->mask |= SD_BUS_CREDS_PPID;
                                                 continue;
                                         }
                                 }
@@ -941,7 +960,17 @@ int bus_creds_add_more(sd_bus_creds *c, uint64_t mask, pid_t pid, pid_t tid) {
 
         if (missing & SD_BUS_CREDS_EXE) {
                 r = get_process_exe(pid, &c->exe);
-                if (r < 0) {
+                if (r == -ESRCH) {
+                        /* Unfortunately we cannot really distuingish
+                         * the case here where the process does not
+                         * exist, and /proc/$PID/exe being unreadable
+                         * because $PID is a kernel thread. Hence,
+                         * assume it is a kernel thread, and rely on
+                         * that this case is caught with a later
+                         * call. */
+                        c->exe = NULL;
+                        c->mask |= SD_BUS_CREDS_EXE;
+                } else if (r < 0) {
                         if (r != -EPERM && r != -EACCES)
                                 return r;
                 } else
@@ -953,17 +982,18 @@ int bus_creds_add_more(sd_bus_creds *c, uint64_t mask, pid_t pid, pid_t tid) {
 
                 p = procfs_file_alloca(pid, "cmdline");
                 r = read_full_file(p, &c->cmdline, &c->cmdline_size);
+                if (r == -ENOENT)
+                        return -ESRCH;
                 if (r < 0) {
-                        if (r == -ENOENT)
-                                return -ESRCH;
                         if (r != -EPERM && r != -EACCES)
                                 return r;
                 } else {
                         if (c->cmdline_size == 0) {
                                 free(c->cmdline);
                                 c->cmdline = NULL;
-                        } else
-                                c->mask |= SD_BUS_CREDS_CMDLINE;
+                        }
+
+                        c->mask |= SD_BUS_CREDS_CMDLINE;
                 }
         }
 
@@ -974,9 +1004,9 @@ int bus_creds_add_more(sd_bus_creds *c, uint64_t mask, pid_t pid, pid_t tid) {
                         return -ENOMEM;
 
                 r = read_one_line_file(p, &c->tid_comm);
+                if (r == -ENOENT)
+                        return -ESRCH;
                 if (r < 0) {
-                        if (r == -ENOENT)
-                                return -ESRCH;
                         if (r != -EPERM && r != -EACCES)
                                 return r;
                 } else
@@ -1005,8 +1035,12 @@ int bus_creds_add_more(sd_bus_creds *c, uint64_t mask, pid_t pid, pid_t tid) {
 
         if (missing & SD_BUS_CREDS_AUDIT_SESSION_ID) {
                 r = audit_session_from_pid(pid, &c->audit_session_id);
-                if (r < 0) {
-                        if (r != -EOPNOTSUPP && r != -ENXIO && r != -ENOENT && r != -EPERM && r != -EACCES)
+                if (r == -ENXIO) {
+                        /* ENXIO means: no audit session id assigned */
+                        c->audit_session_id = AUDIT_SESSION_INVALID;
+                        c->mask |= SD_BUS_CREDS_AUDIT_SESSION_ID;
+                } else if (r < 0) {
+                        if (r != -EOPNOTSUPP && r != -ENOENT && r != -EPERM && r != -EACCES)
                                 return r;
                 } else
                         c->mask |= SD_BUS_CREDS_AUDIT_SESSION_ID;
@@ -1014,8 +1048,12 @@ int bus_creds_add_more(sd_bus_creds *c, uint64_t mask, pid_t pid, pid_t tid) {
 
         if (missing & SD_BUS_CREDS_AUDIT_LOGIN_UID) {
                 r = audit_loginuid_from_pid(pid, &c->audit_login_uid);
-                if (r < 0) {
-                        if (r != -EOPNOTSUPP && r != -ENXIO && r != -ENOENT && r != -EPERM && r != -EACCES)
+                if (r == -ENXIO) {
+                        /* ENXIO means: no audit login uid assigned */
+                        c->audit_login_uid = UID_INVALID;
+                        c->mask |= SD_BUS_CREDS_AUDIT_LOGIN_UID;
+                } else if (r < 0) {
+                        if (r != -EOPNOTSUPP && r != -ENOENT && r != -EPERM && r != -EACCES)
                                 return r;
                 } else
                         c->mask |= SD_BUS_CREDS_AUDIT_LOGIN_UID;
@@ -1023,13 +1061,28 @@ int bus_creds_add_more(sd_bus_creds *c, uint64_t mask, pid_t pid, pid_t tid) {
 
         if (missing & SD_BUS_CREDS_TTY) {
                 r = get_ctty(pid, NULL, &c->tty);
-                if (r < 0) {
+                if (r == -ENXIO) {
+                        /* ENXIO means: process has no controlling TTY */
+                        c->tty = NULL;
+                        c->mask |= SD_BUS_CREDS_TTY;
+                } else if (r < 0) {
                         if (r != -EPERM && r != -EACCES && r != -ENOENT)
                                 return r;
                 } else
                         c->mask |= SD_BUS_CREDS_TTY;
         }
 
+        /* In case only the exe path was to be read we cannot
+         * distuingish the case where the exe path was unreadable
+         * because the process was a kernel thread, or when the
+         * process didn't exist at all. Hence, let's do a final check,
+         * to be sure. */
+        if (!pid_is_alive(pid))
+                return -ESRCH;
+
+        if (tid > 0 && tid != pid && !pid_is_unwaited(tid))
+                return -ESRCH;
+
         c->augmented = missing & c->mask;
 
         return 0;
@@ -1112,14 +1165,22 @@ int bus_creds_extend_by_pid(sd_bus_creds *c, uint64_t mask, sd_bus_creds **ret)
         }
 
         if (c->mask & mask & SD_BUS_CREDS_SUPPLEMENTARY_GIDS) {
-                n->supplementary_gids = newdup(gid_t, c->supplementary_gids, c->n_supplementary_gids);
-                if (!n->supplementary_gids)
-                        return -ENOMEM;
-                n->n_supplementary_gids = c->n_supplementary_gids;
+                if (c->supplementary_gids) {
+                        n->supplementary_gids = newdup(gid_t, c->supplementary_gids, c->n_supplementary_gids);
+                        if (!n->supplementary_gids)
+                                return -ENOMEM;
+                        n->n_supplementary_gids = c->n_supplementary_gids;
+                } else {
+                        n->supplementary_gids = NULL;
+                        n->n_supplementary_gids = 0;
+                }
+
                 n->mask |= SD_BUS_CREDS_SUPPLEMENTARY_GIDS;
         }
 
         if (c->mask & mask & SD_BUS_CREDS_COMM) {
+                assert(c->comm);
+
                 n->comm = strdup(c->comm);
                 if (!n->comm)
                         return -ENOMEM;
@@ -1128,6 +1189,8 @@ int bus_creds_extend_by_pid(sd_bus_creds *c, uint64_t mask, sd_bus_creds **ret)
         }
 
         if (c->mask & mask & SD_BUS_CREDS_TID_COMM) {
+                assert(c->tid_comm);
+
                 n->tid_comm = strdup(c->tid_comm);
                 if (!n->tid_comm)
                         return -ENOMEM;
@@ -1136,23 +1199,34 @@ int bus_creds_extend_by_pid(sd_bus_creds *c, uint64_t mask, sd_bus_creds **ret)
         }
 
         if (c->mask & mask & SD_BUS_CREDS_EXE) {
-                n->exe = strdup(c->exe);
-                if (!n->exe)
-                        return -ENOMEM;
+                if (c->exe) {
+                        n->exe = strdup(c->exe);
+                        if (!n->exe)
+                                return -ENOMEM;
+                } else
+                        n->exe = NULL;
 
                 n->mask |= SD_BUS_CREDS_EXE;
         }
 
         if (c->mask & mask & SD_BUS_CREDS_CMDLINE) {
-                n->cmdline = memdup(c->cmdline, c->cmdline_size);
-                if (!n->cmdline)
-                        return -ENOMEM;
+                if (c->cmdline) {
+                        n->cmdline = memdup(c->cmdline, c->cmdline_size);
+                        if (!n->cmdline)
+                                return -ENOMEM;
+
+                        n->cmdline_size = c->cmdline_size;
+                } else {
+                        n->cmdline = NULL;
+                        n->cmdline_size = 0;
+                }
 
-                n->cmdline_size = c->cmdline_size;
                 n->mask |= SD_BUS_CREDS_CMDLINE;
         }
 
         if (c->mask & mask & (SD_BUS_CREDS_CGROUP|SD_BUS_CREDS_SESSION|SD_BUS_CREDS_UNIT|SD_BUS_CREDS_USER_UNIT|SD_BUS_CREDS_SLICE|SD_BUS_CREDS_OWNER_UID)) {
+                assert(c->cgroup);
+
                 n->cgroup = strdup(c->cgroup);
                 if (!n->cgroup)
                         return -ENOMEM;
@@ -1165,6 +1239,8 @@ int bus_creds_extend_by_pid(sd_bus_creds *c, uint64_t mask, sd_bus_creds **ret)
         }
 
         if (c->mask & mask & (SD_BUS_CREDS_EFFECTIVE_CAPS|SD_BUS_CREDS_PERMITTED_CAPS|SD_BUS_CREDS_INHERITABLE_CAPS|SD_BUS_CREDS_BOUNDING_CAPS)) {
+                assert(c->capability);
+
                 n->capability = memdup(c->capability, DIV_ROUND_UP(cap_last_cap(), 32U) * 4 * 4);
                 if (!n->capability)
                         return -ENOMEM;
@@ -1173,6 +1249,8 @@ int bus_creds_extend_by_pid(sd_bus_creds *c, uint64_t mask, sd_bus_creds **ret)
         }
 
         if (c->mask & mask & SD_BUS_CREDS_SELINUX_CONTEXT) {
+                assert(c->label);
+
                 n->label = strdup(c->label);
                 if (!n->label)
                         return -ENOMEM;
@@ -1199,6 +1277,8 @@ int bus_creds_extend_by_pid(sd_bus_creds *c, uint64_t mask, sd_bus_creds **ret)
         }
 
         if (c->mask & mask & SD_BUS_CREDS_UNIQUE_NAME) {
+                assert(c->unique_name);
+
                 n->unique_name = strdup(c->unique_name);
                 if (!n->unique_name)
                         return -ENOMEM;
@@ -1206,15 +1286,20 @@ int bus_creds_extend_by_pid(sd_bus_creds *c, uint64_t mask, sd_bus_creds **ret)
         }
 
         if (c->mask & mask & SD_BUS_CREDS_WELL_KNOWN_NAMES) {
-                n->well_known_names = strv_copy(c->well_known_names);
-                if (!n->well_known_names)
-                        return -ENOMEM;
+                if (strv_isempty(c->well_known_names))
+                        n->well_known_names = NULL;
+                else {
+                        n->well_known_names = strv_copy(c->well_known_names);
+                        if (!n->well_known_names)
+                                return -ENOMEM;
+                }
                 n->well_known_names_driver = c->well_known_names_driver;
                 n->well_known_names_local = c->well_known_names_local;
                 n->mask |= SD_BUS_CREDS_WELL_KNOWN_NAMES;
         }
 
         if (c->mask & mask & SD_BUS_CREDS_DESCRIPTION) {
+                assert(c->description);
                 n->description = strdup(c->description);
                 if (!n->description)
                         return -ENOMEM;
diff --git a/src/libsystemd/sd-bus/bus-dump.c b/src/libsystemd/sd-bus/bus-dump.c
index 396bf36f8a..47a5c6b3a8 100644
--- a/src/libsystemd/sd-bus/bus-dump.c
+++ b/src/libsystemd/sd-bus/bus-dump.c
@@ -331,13 +331,11 @@ static void dump_capabilities(
 }
 
 int bus_creds_dump(sd_bus_creds *c, FILE *f, bool terse) {
-        bool audit_sessionid_is_set = false, audit_loginuid_is_set = false;
-        const char *u = NULL, *uu = NULL, *s = NULL, *sl = NULL;
         uid_t owner, audit_loginuid;
         uint32_t audit_sessionid;
         char **cmdline = NULL, **well_known = NULL;
-        const char *prefix, *color, *suffix;
-        int r;
+        const char *prefix, *color, *suffix, *s;
+        int r, q, v, w;
 
         assert(c);
 
@@ -362,8 +360,12 @@ int bus_creds_dump(sd_bus_creds *c, FILE *f, bool terse) {
                 fprintf(f, "%sPID=%s"PID_FMT"%s", prefix, color, c->pid, suffix);
         if (c->mask & SD_BUS_CREDS_TID)
                 fprintf(f, "%sTID=%s"PID_FMT"%s", prefix, color, c->tid, suffix);
-        if (c->mask & SD_BUS_CREDS_PPID)
-                fprintf(f, "%sPPID=%s"PID_FMT"%s", prefix, color, c->ppid, suffix);
+        if (c->mask & SD_BUS_CREDS_PPID) {
+                if (c->ppid == 0)
+                        fprintf(f, "%sPPID=%sn/a%s", prefix, color, suffix);
+                else
+                        fprintf(f, "%sPPID=%s"PID_FMT"%s", prefix, color, c->ppid, suffix);
+        }
         if (c->mask & SD_BUS_CREDS_TTY)
                 fprintf(f, "%sTTY=%s%s%s", prefix, color, strna(c->tty), suffix);
 
@@ -409,12 +411,13 @@ int bus_creds_dump(sd_bus_creds *c, FILE *f, bool terse) {
         if (c->mask & SD_BUS_CREDS_TID_COMM)
                 fprintf(f, "%sTIDComm=%s%s%s", prefix, color, c->tid_comm, suffix);
         if (c->mask & SD_BUS_CREDS_EXE)
-                fprintf(f, "%sExe=%s%s%s", prefix, color, c->exe, suffix);
+                fprintf(f, "%sExe=%s%s%s", prefix, color, strna(c->exe), suffix);
 
         if (terse && (c->mask & (SD_BUS_CREDS_EXE|SD_BUS_CREDS_COMM|SD_BUS_CREDS_TID_COMM)))
                 fputs("\n", f);
 
-        if (sd_bus_creds_get_cmdline(c, &cmdline) >= 0) {
+        r = sd_bus_creds_get_cmdline(c, &cmdline);
+        if (r >= 0) {
                 char **i;
 
                 fprintf(f, "%sCommandLine=%s", prefix, color);
@@ -426,7 +429,8 @@ int bus_creds_dump(sd_bus_creds *c, FILE *f, bool terse) {
                 }
 
                 fprintf(f, "%s", suffix);
-        }
+        } else if (r != -ENODATA)
+                fprintf(f, "%sCommandLine=%sn/a%s", prefix, color, suffix);
 
         if (c->mask & SD_BUS_CREDS_SELINUX_CONTEXT)
                 fprintf(f, "%sLabel=%s%s%s", prefix, color, c->label, suffix);
@@ -438,32 +442,38 @@ int bus_creds_dump(sd_bus_creds *c, FILE *f, bool terse) {
 
         if (c->mask & SD_BUS_CREDS_CGROUP)
                 fprintf(f, "%sCGroup=%s%s%s", prefix, color, c->cgroup, suffix);
-        (void) sd_bus_creds_get_unit(c, &u);
-        if (u)
-                fprintf(f, "%sUnit=%s%s%s", prefix, color, u, suffix);
-        (void) sd_bus_creds_get_user_unit(c, &uu);
-        if (uu)
-                fprintf(f, "%sUserUnit=%s%s%s", prefix, color, uu, suffix);
-        (void) sd_bus_creds_get_slice(c, &sl);
-        if (sl)
-                fprintf(f, "%sSlice=%s%s%s", prefix, color, sl, suffix);
-        (void) sd_bus_creds_get_session(c, &s);
-        if (s)
-                fprintf(f, "%sSession=%s%s%s", prefix, color, s, suffix);
-
-        if (terse && ((c->mask & SD_BUS_CREDS_CGROUP) || u || uu || sl || s))
+        s = NULL;
+        r = sd_bus_creds_get_unit(c, &s);
+        if (r != -ENODATA)
+                fprintf(f, "%sUnit=%s%s%s", prefix, color, strna(s), suffix);
+        s = NULL;
+        q = sd_bus_creds_get_user_unit(c, &s);
+        if (q != -ENODATA)
+                fprintf(f, "%sUserUnit=%s%s%s", prefix, color, strna(s), suffix);
+        s = NULL;
+        v = sd_bus_creds_get_slice(c, &s);
+        if (v != -ENODATA)
+                fprintf(f, "%sSlice=%s%s%s", prefix, color, strna(s), suffix);
+        s = NULL;
+        w = sd_bus_creds_get_session(c, &s);
+        if (w != -ENODATA)
+                fprintf(f, "%sSession=%s%s%s", prefix, color, strna(s), suffix);
+
+        if (terse && ((c->mask & SD_BUS_CREDS_CGROUP) || r != -ENODATA || q != -ENODATA || v != -ENODATA || w != -ENODATA))
                 fputs("\n", f);
 
-        if (sd_bus_creds_get_audit_login_uid(c, &audit_loginuid) >= 0) {
-                audit_loginuid_is_set = true;
+        r = sd_bus_creds_get_audit_login_uid(c, &audit_loginuid);
+        if (r >= 0)
                 fprintf(f, "%sAuditLoginUID=%s"UID_FMT"%s", prefix, color, audit_loginuid, suffix);
-        }
-        if (sd_bus_creds_get_audit_session_id(c, &audit_sessionid) >= 0) {
-                audit_sessionid_is_set = true;
+        else if (r != -ENODATA)
+                fprintf(f, "%sAuditLoginUID=%sn/a%s", prefix, color, suffix);
+        q = sd_bus_creds_get_audit_session_id(c, &audit_sessionid);
+        if (q >= 0)
                 fprintf(f, "%sAuditSessionID=%s%"PRIu32"%s", prefix, color, audit_sessionid, suffix);
-        }
+        else if (q != -ENODATA)
+                fprintf(f, "%sAuditSessionID=%sn/a%s", prefix, color, suffix);
 
-        if (terse && (audit_loginuid_is_set || audit_sessionid_is_set))
+        if (terse && (r != -ENODATA || q != -ENODATA))
                 fputs("\n", f);
 
         if (c->mask & SD_BUS_CREDS_UNIQUE_NAME)
diff --git a/src/libsystemd/sd-bus/bus-kernel.c b/src/libsystemd/sd-bus/bus-kernel.c
index a8c04b98a9..556b5eb704 100644
--- a/src/libsystemd/sd-bus/bus-kernel.c
+++ b/src/libsystemd/sd-bus/bus-kernel.c
@@ -598,6 +598,9 @@ static int bus_kernel_make_message(sd_bus *bus, struct kdbus_msg *k) {
                         if (d->pids.ppid > 0) {
                                 m->creds.ppid = (pid_t) d->pids.ppid;
                                 m->creds.mask |= SD_BUS_CREDS_PPID & bus->creds_mask;
+                        } else if (d->pids.pid == 1) {
+                                m->creds.ppid = 0;
+                                m->creds.mask |= SD_BUS_CREDS_PPID & bus->creds_mask;
                         }
 
                         break;
@@ -686,15 +689,11 @@ static int bus_kernel_make_message(sd_bus *bus, struct kdbus_msg *k) {
                         break;
 
                 case KDBUS_ITEM_AUDIT:
-                        if ((uint32_t) d->audit.sessionid != (uint32_t) -1) {
-                                m->creds.audit_session_id = (uint32_t) d->audit.sessionid;
-                                m->creds.mask |= SD_BUS_CREDS_AUDIT_SESSION_ID & bus->creds_mask;
-                        }
+                        m->creds.audit_session_id = (uint32_t) d->audit.sessionid;
+                        m->creds.mask |= SD_BUS_CREDS_AUDIT_SESSION_ID & bus->creds_mask;
 
-                        if ((uid_t) d->audit.loginuid != UID_INVALID) {
-                                m->creds.audit_login_uid = (uid_t) d->audit.loginuid;
-                                m->creds.mask |= SD_BUS_CREDS_AUDIT_LOGIN_UID & bus->creds_mask;
-                        }
+                        m->creds.audit_login_uid = (uid_t) d->audit.loginuid;
+                        m->creds.mask |= SD_BUS_CREDS_AUDIT_LOGIN_UID & bus->creds_mask;
                         break;
 
                 case KDBUS_ITEM_CAPS:
diff --git a/src/shared/audit.c b/src/shared/audit.c
index 84181d3321..54148fcf18 100644
--- a/src/shared/audit.c
+++ b/src/shared/audit.c
@@ -46,7 +46,7 @@ int audit_session_from_pid(pid_t pid, uint32_t *id) {
         if (r < 0)
                 return r;
 
-        if (u == (uint32_t) -1 || u <= 0)
+        if (u == AUDIT_SESSION_INVALID || u <= 0)
                 return -ENXIO;
 
         *id = u;
diff --git a/src/shared/audit.h b/src/shared/audit.h
index 781866ae1c..6de331c73e 100644
--- a/src/shared/audit.h
+++ b/src/shared/audit.h
@@ -25,6 +25,7 @@
 #include <stdbool.h>
 #include <sys/types.h>
 
+#define AUDIT_SESSION_INVALID ((uint32_t) -1)
 
 int audit_session_from_pid(pid_t pid, uint32_t *id);
 int audit_loginuid_from_pid(pid_t pid, uid_t *uid);
diff --git a/src/shared/cgroup-util.c b/src/shared/cgroup-util.c
index 5b04702ac2..7521b8b5f9 100644
--- a/src/shared/cgroup-util.c
+++ b/src/shared/cgroup-util.c
@@ -1150,7 +1150,7 @@ int cg_path_decode_unit(const char *cgroup, char **unit){
         c = cg_unescape(c);
 
         if (!unit_name_is_valid(c, TEMPLATE_INVALID))
-                return -EINVAL;
+                return -ENXIO;
 
         s = strdup(c);
         if (!s)
@@ -1258,7 +1258,7 @@ int cg_path_get_user_unit(const char *path, char **unit) {
         if (!t)
                 t = skip_user_manager(e);
         if (!t)
-                return -ENOENT;
+                return -ENXIO;
 
         /* ... and skip more slices if there are any */
         e = skip_slices(t);
@@ -1318,17 +1318,17 @@ int cg_path_get_session(const char *path, char **session) {
 
         n = strchrnul(e, '/');
         if (e == n)
-                return -ENOENT;
+                return -ENXIO;
 
         s = strndupa(e, n - e);
         s = cg_unescape(s);
 
         x = startswith(s, "session-");
         if (!x)
-                return -ENOENT;
+                return -ENXIO;
         y = endswith(x, ".scope");
         if (!y || x == y)
-                return -ENOENT;
+                return -ENXIO;
 
         if (session) {
                 char *r;
@@ -1369,17 +1369,17 @@ int cg_path_get_owner_uid(const char *path, uid_t *uid) {
 
         start = startswith(slice, "user-");
         if (!start)
-                return -ENOENT;
+                return -ENXIO;
         end = endswith(slice, ".slice");
         if (!end)
-                return -ENOENT;
+                return -ENXIO;
 
         s = strndupa(start, end - start);
         if (!s)
-                return -ENOENT;
+                return -ENXIO;
 
         if (parse_uid(s, &u) < 0)
-                return -EIO;
+                return -ENXIO;
 
         if (uid)
                 *uid = u;
@@ -1415,7 +1415,7 @@ int cg_path_get_slice(const char *p, char **slice) {
                         char *s;
 
                         if (!e)
-                                return -ENOENT;
+                                return -ENXIO;
 
                         s = strndup(e, m);
                         if (!s)
diff --git a/src/shared/terminal-util.c b/src/shared/terminal-util.c
index f5b6590993..042b88f222 100644
--- a/src/shared/terminal-util.c
+++ b/src/shared/terminal-util.c
@@ -1009,7 +1009,7 @@ int get_ctty_devnr(pid_t pid, dev_t *d) {
                 return -EIO;
 
         if (major(ttynr) == 0 && minor(ttynr) == 0)
-                return -ENOENT;
+                return -ENXIO;
 
         if (d)
                 *d = (dev_t) ttynr;
diff --git a/src/test/test-cgroup-util.c b/src/test/test-cgroup-util.c
index aca4f868a1..fff9ec22cf 100644
--- a/src/test/test-cgroup-util.c
+++ b/src/test/test-cgroup-util.c
@@ -40,11 +40,11 @@ static void test_path_decode_unit(void) {
         check_p_d_u("getty@tty2.service", 0, "getty@tty2.service");
         check_p_d_u("getty@tty2.service/", 0, "getty@tty2.service");
         check_p_d_u("getty@tty2.service/xxx", 0, "getty@tty2.service");
-        check_p_d_u("getty@.service/", -EINVAL, NULL);
-        check_p_d_u("getty@.service", -EINVAL, NULL);
+        check_p_d_u("getty@.service/", -ENXIO, NULL);
+        check_p_d_u("getty@.service", -ENXIO, NULL);
         check_p_d_u("getty.service", 0, "getty.service");
-        check_p_d_u("getty", -EINVAL, NULL);
-        check_p_d_u("getty/waldo", -EINVAL, NULL);
+        check_p_d_u("getty", -ENXIO, NULL);
+        check_p_d_u("getty/waldo", -ENXIO, NULL);
         check_p_d_u("_cpu.service", 0, "cpu.service");
 }
 
@@ -64,12 +64,12 @@ static void test_path_get_unit(void) {
         check_p_g_u("/system.slice/getty@tty5.service/aaa/bbb", 0, "getty@tty5.service");
         check_p_g_u("/system.slice/getty@tty5.service/", 0, "getty@tty5.service");
         check_p_g_u("/system.slice/getty@tty6.service/tty5", 0, "getty@tty6.service");
-        check_p_g_u("sadfdsafsda", -EINVAL, NULL);
-        check_p_g_u("/system.slice/getty####@tty6.service/xxx", -EINVAL, NULL);
+        check_p_g_u("sadfdsafsda", -ENXIO, NULL);
+        check_p_g_u("/system.slice/getty####@tty6.service/xxx", -ENXIO, NULL);
         check_p_g_u("/system.slice/system-waldo.slice/foobar.service/sdfdsaf", 0, "foobar.service");
         check_p_g_u("/system.slice/system-waldo.slice/_cpu.service/sdfdsaf", 0, "cpu.service");
         check_p_g_u("/user.slice/user-1000.slice/user@1000.service/server.service", 0, "user@1000.service");
-        check_p_g_u("/user.slice/user-1000.slice/user@.service/server.service", -EINVAL, NULL);
+        check_p_g_u("/user.slice/user-1000.slice/user@.service/server.service", -ENXIO, NULL);
 }
 
 static void check_p_g_u_u(const char *path, int code, const char *result) {
@@ -87,15 +87,15 @@ static void test_path_get_user_unit(void) {
         check_p_g_u_u("/user.slice/user-1000.slice/session-2.scope/waldo.slice/foobar.service", 0, "foobar.service");
         check_p_g_u_u("/user.slice/user-1002.slice/session-2.scope/foobar.service/waldo", 0, "foobar.service");
         check_p_g_u_u("/user.slice/user-1000.slice/session-2.scope/foobar.service/waldo/uuuux", 0, "foobar.service");
-        check_p_g_u_u("/user.slice/user-1000.slice/session-2.scope/waldo/waldo/uuuux", -EINVAL, NULL);
+        check_p_g_u_u("/user.slice/user-1000.slice/session-2.scope/waldo/waldo/uuuux", -ENXIO, NULL);
         check_p_g_u_u("/user.slice/user-1000.slice/session-2.scope/foobar@pie.service/pa/po", 0, "foobar@pie.service");
         check_p_g_u_u("/session-2.scope/foobar@pie.service/pa/po", 0, "foobar@pie.service");
         check_p_g_u_u("/xyz.slice/xyz-waldo.slice/session-77.scope/foobar@pie.service/pa/po", 0, "foobar@pie.service");
-        check_p_g_u_u("/meh.service", -ENOENT, NULL);
+        check_p_g_u_u("/meh.service", -ENXIO, NULL);
         check_p_g_u_u("/session-3.scope/_cpu.service", 0, "cpu.service");
         check_p_g_u_u("/user.slice/user-1000.slice/user@1000.service/server.service", 0, "server.service");
         check_p_g_u_u("/user.slice/user-1000.slice/user@1000.service/foobar.slice/foobar@pie.service", 0, "foobar@pie.service");
-        check_p_g_u_u("/user.slice/user-1000.slice/user@.service/server.service", -ENOENT, NULL);
+        check_p_g_u_u("/user.slice/user-1000.slice/user@.service/server.service", -ENXIO, NULL);
 }
 
 static void check_p_g_s(const char *path, int code, const char *result) {
@@ -108,8 +108,8 @@ static void check_p_g_s(const char *path, int code, const char *result) {
 static void test_path_get_session(void) {
         check_p_g_s("/user.slice/user-1000.slice/session-2.scope/foobar.service", 0, "2");
         check_p_g_s("/session-3.scope", 0, "3");
-        check_p_g_s("/session-.scope", -ENOENT, NULL);
-        check_p_g_s("", -ENOENT, NULL);
+        check_p_g_s("/session-.scope", -ENXIO, NULL);
+        check_p_g_s("", -ENXIO, NULL);
 }
 
 static void check_p_g_o_u(const char *path, int code, uid_t result) {
@@ -122,7 +122,7 @@ static void check_p_g_o_u(const char *path, int code, uid_t result) {
 static void test_path_get_owner_uid(void) {
         check_p_g_o_u("/user.slice/user-1000.slice/session-2.scope/foobar.service", 0, 1000);
         check_p_g_o_u("/user.slice/user-1006.slice", 0, 1006);
-        check_p_g_o_u("", -ENOENT, 0);
+        check_p_g_o_u("", -ENXIO, 0);
 }
 
 static void test_get_paths(void) {
diff --git a/src/test/test-process-util.c b/src/test/test-process-util.c
index 1de100cdae..e4e2efecd5 100644
--- a/src/test/test-process-util.c
+++ b/src/test/test-process-util.c
@@ -44,9 +44,8 @@ static void test_get_process_comm(void) {
         if (stat("/proc/1/comm", &st) == 0) {
                 assert_se(get_process_comm(1, &a) >= 0);
                 log_info("pid1 comm: '%s'", a);
-        } else {
+        } else
                 log_warning("/proc/1/comm does not exist.");
-        }
 
         assert_se(get_process_cmdline(1, 0, true, &c) >= 0);
         log_info("pid1 cmdline: '%s'", c);
@@ -87,7 +86,7 @@ static void test_get_process_comm(void) {
         log_info("self strlen(environ): '%zu'", strlen(env));
 
         if (!detect_container(NULL))
-                assert_se(get_ctty_devnr(1, &h) == -ENOENT);
+                assert_se(get_ctty_devnr(1, &h) == -ENXIO);
 
         getenv_for_pid(1, "PATH", &i);
         log_info("pid1 $PATH: '%s'", strna(i));