diff --git a/src/basic/socket-util.c b/src/basic/socket-util.c
index a23dd6cbed5..0be098df2ea 100644
--- a/src/basic/socket-util.c
+++ b/src/basic/socket-util.c
@@ -818,10 +818,7 @@ ssize_t send_one_fd_iov_sa(
                 const struct sockaddr *sa, socklen_t len,
                 int flags) {
 
-        union {
-                struct cmsghdr cmsghdr;
-                uint8_t buf[CMSG_SPACE(sizeof(int))];
-        } control = {};
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(int))) control = {};
         struct msghdr mh = {
                 .msg_name = (struct sockaddr*) sa,
                 .msg_namelen = len,
@@ -875,10 +872,7 @@ ssize_t receive_one_fd_iov(
                 int flags,
                 int *ret_fd) {
 
-        union {
-                struct cmsghdr cmsghdr;
-                uint8_t buf[CMSG_SPACE(sizeof(int))];
-        } control = {};
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(int))) control;
         struct msghdr mh = {
                 .msg_control = &control,
                 .msg_controllen = sizeof(control),
diff --git a/src/basic/socket-util.h b/src/basic/socket-util.h
index fba4efef814..6f366c04299 100644
--- a/src/basic/socket-util.h
+++ b/src/basic/socket-util.h
@@ -166,6 +166,17 @@ struct cmsghdr* cmsg_find(struct msghdr *mh, int level, int type, socklen_t leng
                 (ctype*) (_found ? CMSG_DATA(_found) : NULL);         \
         })
 
+/* Resolves to a type that can carry cmsghdr structures. Make sure things are properly aligned, i.e. the type
+ * itself is placed properly in memory and the size is also aligned to what's appropriate for "cmsghdr"
+ * structures. */
+#define CMSG_BUFFER_TYPE(size)                                          \
+        union {                                                         \
+                struct cmsghdr cmsghdr;                                 \
+                uint8_t buf[size];                                      \
+                uint8_t align_check[(size) >= CMSG_SPACE(0) &&          \
+                                    (size) == CMSG_ALIGN(size) ? 1 : -1]; \
+        }
+
 /*
  * Certain hardware address types (e.g Infiniband) do not fit into sll_addr
  * (8 bytes) and run over the structure. This macro returns the correct size that
diff --git a/src/core/manager.c b/src/core/manager.c
index 7c207bed6e7..09dc92d599a 100644
--- a/src/core/manager.c
+++ b/src/core/manager.c
@@ -2349,11 +2349,8 @@ static int manager_dispatch_notify_fd(sd_event_source *source, int fd, uint32_t
                 .iov_base = buf,
                 .iov_len = sizeof(buf)-1,
         };
-        union {
-                struct cmsghdr cmsghdr;
-                uint8_t buf[CMSG_SPACE(sizeof(struct ucred)) +
-                            CMSG_SPACE(sizeof(int) * NOTIFY_FD_MAX)];
-        } control = {};
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct ucred)) +
+                         CMSG_SPACE(sizeof(int) * NOTIFY_FD_MAX)) control;
         struct msghdr msghdr = {
                 .msg_iov = &iovec,
                 .msg_iovlen = 1,
diff --git a/src/coredump/coredump.c b/src/coredump/coredump.c
index ff4238c91d7..42231dbd6b6 100644
--- a/src/coredump/coredump.c
+++ b/src/coredump/coredump.c
@@ -884,10 +884,7 @@ static int process_socket(int fd) {
         log_debug("Processing coredump received on stdin...");
 
         for (;;) {
-                union {
-                        struct cmsghdr cmsghdr;
-                        uint8_t buf[CMSG_SPACE(sizeof(int))];
-                } control = {};
+                CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(int))) control;
                 struct msghdr mh = {
                         .msg_control = &control,
                         .msg_controllen = sizeof(control),
diff --git a/src/home/homed-manager.c b/src/home/homed-manager.c
index 8ea93120d07..70673fc84d6 100644
--- a/src/home/homed-manager.c
+++ b/src/home/homed-manager.c
@@ -946,10 +946,7 @@ static ssize_t read_datagram(int fd, struct ucred *ret_sender, void **ret) {
                 return -ENOMEM;
 
         if (ret_sender) {
-                union {
-                        struct cmsghdr cmsghdr;
-                        uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
-                } control;
+                CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct ucred))) control;
                 bool found_ucred = false;
                 struct cmsghdr *cmsg;
                 struct msghdr mh;
diff --git a/src/import/importd.c b/src/import/importd.c
index 9408edece10..d799a10f94b 100644
--- a/src/import/importd.c
+++ b/src/import/importd.c
@@ -550,11 +550,8 @@ static int manager_on_notify(sd_event_source *s, int fd, uint32_t revents, void
                 .iov_base = buf,
                 .iov_len = sizeof(buf)-1,
         };
-        union {
-                struct cmsghdr cmsghdr;
-                uint8_t buf[CMSG_SPACE(sizeof(struct ucred)) +
-                            CMSG_SPACE(sizeof(int) * NOTIFY_FD_MAX)];
-        } control = {};
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct ucred)) +
+                         CMSG_SPACE(sizeof(int) * NOTIFY_FD_MAX)) control;
         struct msghdr msghdr = {
                 .msg_iov = &iovec,
                 .msg_iovlen = 1,
diff --git a/src/journal/journald-server.c b/src/journal/journald-server.c
index 981a569453a..9efa65a2942 100644
--- a/src/journal/journald-server.c
+++ b/src/journal/journald-server.c
@@ -1268,21 +1268,14 @@ int server_process_datagram(
         int *fds = NULL, v = 0;
         size_t n_fds = 0;
 
-        union {
-                struct cmsghdr cmsghdr;
-
-                /* We use NAME_MAX space for the SELinux label
-                 * here. The kernel currently enforces no
-                 * limit, but according to suggestions from
-                 * the SELinux people this will change and it
-                 * will probably be identical to NAME_MAX. For
-                 * now we use that, but this should be updated
-                 * one day when the final limit is known. */
-                uint8_t buf[CMSG_SPACE(sizeof(struct ucred)) +
-                            CMSG_SPACE(sizeof(struct timeval)) +
-                            CMSG_SPACE(sizeof(int)) + /* fd */
-                            CMSG_SPACE(NAME_MAX)]; /* selinux label */
-        } control = {};
+        /* We use NAME_MAX space for the SELinux label here. The kernel currently enforces no limit, but
+         * according to suggestions from the SELinux people this will change and it will probably be
+         * identical to NAME_MAX. For now we use that, but this should be updated one day when the final
+         * limit is known. */
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct ucred)) +
+                         CMSG_SPACE(sizeof(struct timeval)) +
+                         CMSG_SPACE(sizeof(int)) + /* fd */
+                         CMSG_SPACE(NAME_MAX) /* selinux label */) control;
 
         union sockaddr_union sa = {};
 
diff --git a/src/journal/journald-stream.c b/src/journal/journald-stream.c
index 202ac3cda28..4dadbd62bec 100644
--- a/src/journal/journald-stream.c
+++ b/src/journal/journald-stream.c
@@ -489,7 +489,7 @@ static int stdout_stream_scan(StdoutStream *s, bool force_flush) {
 }
 
 static int stdout_stream_process(sd_event_source *es, int fd, uint32_t revents, void *userdata) {
-        uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct ucred))) control;
         StdoutStream *s = userdata;
         struct ucred *ucred;
         struct iovec iovec;
@@ -500,8 +500,8 @@ static int stdout_stream_process(sd_event_source *es, int fd, uint32_t revents,
         struct msghdr msghdr = {
                 .msg_iov = &iovec,
                 .msg_iovlen = 1,
-                .msg_control = buf,
-                .msg_controllen = sizeof(buf),
+                .msg_control = &control,
+                .msg_controllen = sizeof(control),
         };
 
         assert(s);
diff --git a/src/journal/journald-syslog.c b/src/journal/journald-syslog.c
index 1325b563854..46013c38784 100644
--- a/src/journal/journald-syslog.c
+++ b/src/journal/journald-syslog.c
@@ -39,10 +39,7 @@ static void forward_syslog_iovec(
                 .msg_iovlen = n_iovec,
         };
         struct cmsghdr *cmsg;
-        union {
-                struct cmsghdr cmsghdr;
-                uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
-        } control;
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct ucred))) control;
         const char *j;
         int r;
 
diff --git a/src/libsystemd-network/icmp6-util.c b/src/libsystemd-network/icmp6-util.c
index 1a51c22a8d0..bdd94867ac3 100644
--- a/src/libsystemd-network/icmp6-util.c
+++ b/src/libsystemd-network/icmp6-util.c
@@ -147,11 +147,9 @@ int icmp6_send_router_solicitation(int s, const struct ether_addr *ether_addr) {
 
 int icmp6_receive(int fd, void *buffer, size_t size, struct in6_addr *dst,
                   triple_timestamp *timestamp) {
-        union {
-                struct cmsghdr cmsghdr;
-                uint8_t buf[CMSG_SPACE(sizeof(int)) + /* ttl */
-                            CMSG_SPACE(sizeof(struct timeval))];
-        } control = {};
+
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(int)) + /* ttl */
+                         CMSG_SPACE(sizeof(struct timeval))) control;
         struct iovec iov = {};
         union sockaddr_union sa = {};
         struct msghdr msg = {
diff --git a/src/libsystemd-network/sd-dhcp-client.c b/src/libsystemd-network/sd-dhcp-client.c
index 47f60d4a2a3..ee0e63e113c 100644
--- a/src/libsystemd-network/sd-dhcp-client.c
+++ b/src/libsystemd-network/sd-dhcp-client.c
@@ -1899,13 +1899,13 @@ static int client_receive_message_raw(
 
         sd_dhcp_client *client = userdata;
         _cleanup_free_ DHCPPacket *packet = NULL;
-        uint8_t cmsgbuf[CMSG_SPACE(sizeof(struct tpacket_auxdata))];
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct tpacket_auxdata))) control;
         struct iovec iov = {};
         struct msghdr msg = {
                 .msg_iov = &iov,
                 .msg_iovlen = 1,
-                .msg_control = cmsgbuf,
-                .msg_controllen = sizeof(cmsgbuf),
+                .msg_control = &control,
+                .msg_controllen = sizeof(control),
         };
         struct cmsghdr *cmsg;
         bool checksum = true;
diff --git a/src/libsystemd-network/sd-dhcp-server.c b/src/libsystemd-network/sd-dhcp-server.c
index 59792af6863..14f2bcb4fb8 100644
--- a/src/libsystemd-network/sd-dhcp-server.c
+++ b/src/libsystemd-network/sd-dhcp-server.c
@@ -267,14 +267,14 @@ static int dhcp_server_send_udp(sd_dhcp_server *server, be32_t destination,
                 .iov_base = message,
                 .iov_len = len,
         };
-        uint8_t cmsgbuf[CMSG_SPACE(sizeof(struct in_pktinfo))] = {};
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct in_pktinfo))) control = {};
         struct msghdr msg = {
                 .msg_name = &dest,
                 .msg_namelen = sizeof(dest.in),
                 .msg_iov = &iov,
                 .msg_iovlen = 1,
-                .msg_control = cmsgbuf,
-                .msg_controllen = sizeof(cmsgbuf),
+                .msg_control = &control,
+                .msg_controllen = sizeof(control),
         };
         struct cmsghdr *cmsg;
         struct in_pktinfo *pktinfo;
@@ -970,14 +970,14 @@ int dhcp_server_handle_message(sd_dhcp_server *server, DHCPMessage *message,
 static int server_receive_message(sd_event_source *s, int fd,
                                   uint32_t revents, void *userdata) {
         _cleanup_free_ DHCPMessage *message = NULL;
-        uint8_t cmsgbuf[CMSG_SPACE(sizeof(struct in_pktinfo))];
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct in_pktinfo))) control;
         sd_dhcp_server *server = userdata;
         struct iovec iov = {};
         struct msghdr msg = {
                 .msg_iov = &iov,
                 .msg_iovlen = 1,
-                .msg_control = cmsgbuf,
-                .msg_controllen = sizeof(cmsgbuf),
+                .msg_control = &control,
+                .msg_controllen = sizeof(control),
         };
         struct cmsghdr *cmsg;
         ssize_t buflen, len;
diff --git a/src/libsystemd/sd-bus/bus-socket.c b/src/libsystemd/sd-bus/bus-socket.c
index e336dbb62ed..acc313d164b 100644
--- a/src/libsystemd/sd-bus/bus-socket.c
+++ b/src/libsystemd/sd-bus/bus-socket.c
@@ -518,10 +518,7 @@ static int bus_socket_read_auth(sd_bus *b) {
         ssize_t k;
         int r;
         void *p;
-        union {
-                struct cmsghdr cmsghdr;
-                uint8_t buf[CMSG_SPACE(sizeof(int) * BUS_FDS_MAX)];
-        } control;
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(int) * BUS_FDS_MAX)) control;
         bool handle_cmsg = false;
 
         assert(b);
@@ -1169,10 +1166,7 @@ int bus_socket_read_message(sd_bus *bus) {
         size_t need;
         int r;
         void *b;
-        union {
-                struct cmsghdr cmsghdr;
-                uint8_t buf[CMSG_SPACE(sizeof(int) * BUS_FDS_MAX)];
-        } control;
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(int) * BUS_FDS_MAX)) control;
         bool handle_cmsg = false;
 
         assert(bus);
diff --git a/src/libsystemd/sd-device/device-monitor.c b/src/libsystemd/sd-device/device-monitor.c
index 42753abe083..20a422c77cf 100644
--- a/src/libsystemd/sd-device/device-monitor.c
+++ b/src/libsystemd/sd-device/device-monitor.c
@@ -361,13 +361,13 @@ int device_monitor_receive_device(sd_device_monitor *m, sd_device **ret) {
                 .iov_base = &buf,
                 .iov_len = sizeof(buf)
         };
-        char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct ucred))) control;
         union sockaddr_union snl;
         struct msghdr smsg = {
                 .msg_iov = &iov,
                 .msg_iovlen = 1,
-                .msg_control = cred_msg,
-                .msg_controllen = sizeof(cred_msg),
+                .msg_control = &control,
+                .msg_controllen = sizeof(control),
                 .msg_name = &snl,
                 .msg_namelen = sizeof(snl),
         };
diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index 43c6b6845ed..8e8881749aa 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -3687,11 +3687,8 @@ static int nspawn_dispatch_notify_fd(sd_event_source *source, int fd, uint32_t r
                 .iov_base = buf,
                 .iov_len = sizeof(buf)-1,
         };
-        union {
-                struct cmsghdr cmsghdr;
-                uint8_t buf[CMSG_SPACE(sizeof(struct ucred)) +
-                            CMSG_SPACE(sizeof(int) * NOTIFY_FD_MAX)];
-        } control = {};
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct ucred)) +
+                         CMSG_SPACE(sizeof(int) * NOTIFY_FD_MAX)) control;
         struct msghdr msghdr = {
                 .msg_iov = &iovec,
                 .msg_iovlen = 1,
diff --git a/src/portable/portable.c b/src/portable/portable.c
index 4a881460dbb..f47a3329fb9 100644
--- a/src/portable/portable.c
+++ b/src/portable/portable.c
@@ -127,10 +127,7 @@ static int send_item(
                 const char *name,
                 int fd) {
 
-        union {
-                struct cmsghdr cmsghdr;
-                uint8_t buf[CMSG_SPACE(sizeof(int))];
-        } control = {};
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(int))) control = {};
         struct iovec iovec;
         struct msghdr mh = {
                 .msg_control = &control,
@@ -168,10 +165,7 @@ static int recv_item(
                 char **ret_name,
                 int *ret_fd) {
 
-        union {
-                struct cmsghdr cmsghdr;
-                uint8_t buf[CMSG_SPACE(sizeof(int))];
-        } control = {};
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(int))) control;
         char buffer[PATH_MAX+2];
         struct iovec iov = IOVEC_INIT(buffer, sizeof(buffer)-1);
         struct msghdr mh = {
diff --git a/src/resolve/resolved-dns-stream.c b/src/resolve/resolved-dns-stream.c
index 9c47cd60e42..bbaffc165ac 100644
--- a/src/resolve/resolved-dns-stream.c
+++ b/src/resolve/resolved-dns-stream.c
@@ -87,11 +87,8 @@ static int dns_stream_complete(DnsStream *s, int error) {
 }
 
 static int dns_stream_identify(DnsStream *s) {
-        union {
-                struct cmsghdr header; /* For alignment */
-                uint8_t buffer[CMSG_SPACE(MAXSIZE(struct in_pktinfo, struct in6_pktinfo))
-                               + EXTRA_CMSG_SPACE /* kernel appears to require extra space */];
-        } control;
+        CMSG_BUFFER_TYPE(CMSG_SPACE(MAXSIZE(struct in_pktinfo, struct in6_pktinfo))
+                         + EXTRA_CMSG_SPACE /* kernel appears to require extra space */) control;
         struct msghdr mh = {};
         struct cmsghdr *cmsg;
         socklen_t sl;
diff --git a/src/resolve/resolved-manager.c b/src/resolve/resolved-manager.c
index 69630cf49d3..1da590b68ac 100644
--- a/src/resolve/resolved-manager.c
+++ b/src/resolve/resolved-manager.c
@@ -741,12 +741,9 @@ Manager *manager_free(Manager *m) {
 
 int manager_recv(Manager *m, int fd, DnsProtocol protocol, DnsPacket **ret) {
         _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
-        union {
-                struct cmsghdr header; /* For alignment */
-                uint8_t buffer[CMSG_SPACE(MAXSIZE(struct in_pktinfo, struct in6_pktinfo))
-                               + CMSG_SPACE(int) /* ttl/hoplimit */
-                               + EXTRA_CMSG_SPACE /* kernel appears to require extra buffer space */];
-        } control;
+        CMSG_BUFFER_TYPE(CMSG_SPACE(MAXSIZE(struct in_pktinfo, struct in6_pktinfo))
+                         + CMSG_SPACE(int) /* ttl/hoplimit */
+                         + EXTRA_CMSG_SPACE /* kernel appears to require extra buffer space */) control;
         union sockaddr_union sa;
         struct iovec iov;
         struct msghdr mh = {
@@ -930,10 +927,8 @@ static int manager_ipv4_send(
                 uint16_t port,
                 const struct in_addr *source,
                 DnsPacket *p) {
-        union {
-                struct cmsghdr header; /* For alignment */
-                uint8_t buffer[CMSG_SPACE(sizeof(struct in_pktinfo))];
-        } control = {};
+
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct in_pktinfo))) control = {};
         union sockaddr_union sa;
         struct iovec iov;
         struct msghdr mh = {
@@ -988,10 +983,7 @@ static int manager_ipv6_send(
                 const struct in6_addr *source,
                 DnsPacket *p) {
 
-        union {
-                struct cmsghdr header; /* For alignment */
-                uint8_t buffer[CMSG_SPACE(sizeof(struct in6_pktinfo))];
-        } control = {};
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct in6_pktinfo))) control = {};
         union sockaddr_union sa;
         struct iovec iov;
         struct msghdr mh = {
diff --git a/src/shared/ask-password-api.c b/src/shared/ask-password-api.c
index e690b0fa6ea..4c5781a11ad 100644
--- a/src/shared/ask-password-api.c
+++ b/src/shared/ask-password-api.c
@@ -859,13 +859,10 @@ int ask_password_agent(
         pollfd[FD_INOTIFY].events = POLLIN;
 
         for (;;) {
+                CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct ucred))) control;
                 char passphrase[LINE_MAX+1];
                 struct iovec iovec;
                 struct ucred *ucred;
-                union {
-                        struct cmsghdr cmsghdr;
-                        uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
-                } control;
                 ssize_t n;
                 int k;
                 usec_t t;
@@ -917,7 +914,6 @@ int ask_password_agent(
 
                 iovec = IOVEC_MAKE(passphrase, sizeof(passphrase));
 
-                zero(control);
                 struct msghdr msghdr = {
                         .msg_iov = &iovec,
                         .msg_iovlen = 1,
diff --git a/src/timesync/timesyncd-manager.c b/src/timesync/timesyncd-manager.c
index 2980f79b16f..dadf213a809 100644
--- a/src/timesync/timesyncd-manager.c
+++ b/src/timesync/timesyncd-manager.c
@@ -407,10 +407,7 @@ static int manager_receive_response(sd_event_source *source, int fd, uint32_t re
                 .iov_base = &ntpmsg,
                 .iov_len = sizeof(ntpmsg),
         };
-        union {
-                struct cmsghdr cmsghdr;
-                uint8_t buf[CMSG_SPACE(sizeof(struct timeval))];
-        } control;
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct timeval))) control;
         union sockaddr_union server_addr;
         struct msghdr msghdr = {
                 .msg_iov = &iov,
diff --git a/src/udev/udev-ctrl.c b/src/udev/udev-ctrl.c
index d067279f3e1..1e51f22e260 100644
--- a/src/udev/udev-ctrl.c
+++ b/src/udev/udev-ctrl.c
@@ -189,12 +189,12 @@ static int udev_ctrl_connection_event_handler(sd_event_source *s, int fd, uint32
         _cleanup_(udev_ctrl_disconnect_and_listen_againp) struct udev_ctrl *uctrl = NULL;
         struct udev_ctrl_msg_wire msg_wire;
         struct iovec iov = IOVEC_MAKE(&msg_wire, sizeof(struct udev_ctrl_msg_wire));
-        char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct ucred))) control;
         struct msghdr smsg = {
                 .msg_iov = &iov,
                 .msg_iovlen = 1,
-                .msg_control = cred_msg,
-                .msg_controllen = sizeof(cred_msg),
+                .msg_control = &control,
+                .msg_controllen = sizeof(control),
         };
         struct cmsghdr *cmsg;
         struct ucred *cred;
diff --git a/src/udev/udevd.c b/src/udev/udevd.c
index cfda47f849b..d3f9d532e18 100644
--- a/src/udev/udevd.c
+++ b/src/udev/udevd.c
@@ -906,10 +906,7 @@ static int on_worker(sd_event_source *s, int fd, uint32_t revents, void *userdat
                         .iov_base = &msg,
                         .iov_len = sizeof(msg),
                 };
-                union {
-                        struct cmsghdr cmsghdr;
-                        uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
-                } control = {};
+                CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct ucred))) control;
                 struct msghdr msghdr = {
                         .msg_iov = &iovec,
                         .msg_iovlen = 1,