X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=src%2Flibsystemd%2Fsd-bus%2Fbus-kernel.c;h=8b961c38eb2ffe6e72c444ba99609a1e823fa909;hp=833ea5574ddbde16fc180ace3973815287e3ec95;hb=f1e3bee216b9eac1d5b00415617cb2ff5e894c10;hpb=8d1db1d154c1134c9bf92b202ef198cc79979ea8

diff --git a/src/libsystemd/sd-bus/bus-kernel.c b/src/libsystemd/sd-bus/bus-kernel.c
index 833ea5574..8b961c38e 100644
--- a/src/libsystemd/sd-bus/bus-kernel.c
+++ b/src/libsystemd/sd-bus/bus-kernel.c
@@ -36,6 +36,7 @@
 #include "bus-kernel.h"
 #include "bus-bloom.h"
 #include "bus-util.h"
+#include "bus-label.h"
 #include "cgroup-util.h"
 
 #define UNIQUE_NAME_MAX (3+DECIMAL_STR_MAX(uint64_t))
@@ -101,20 +102,21 @@ static void append_destination(struct kdbus_item **d, const char *s, size_t leng
         *d = (struct kdbus_item *) ((uint8_t*) *d + (*d)->size);
 }
 
-static void* append_bloom(struct kdbus_item **d, size_t length) {
-        void *r;
+static struct kdbus_bloom_filter *append_bloom(struct kdbus_item **d, size_t length) {
+        struct kdbus_item *i;
 
         assert(d);
 
-        *d = ALIGN8_PTR(*d);
+        i = ALIGN8_PTR(*d);
 
-        (*d)->size = offsetof(struct kdbus_item, data) + length;
-        (*d)->type = KDBUS_ITEM_BLOOM;
-        r = (*d)->data;
+        i->size = offsetof(struct kdbus_item, bloom_filter) +
+                  offsetof(struct kdbus_bloom_filter, data) +
+                  length;
+        i->type = KDBUS_ITEM_BLOOM_FILTER;
 
-        *d = (struct kdbus_item *) ((uint8_t*) *d + (*d)->size);
+        *d = (struct kdbus_item *) ((uint8_t*) i + i->size);
 
-        return r;
+        return &i->bloom_filter;
 }
 
 static void append_fds(struct kdbus_item **d, const int fds[], unsigned n_fds) {
@@ -130,25 +132,28 @@ static void append_fds(struct kdbus_item **d, const int fds[], unsigned n_fds) {
         *d = (struct kdbus_item *) ((uint8_t*) *d + (*d)->size);
 }
 
-static int bus_message_setup_bloom(sd_bus_message *m, void *bloom) {
+static int bus_message_setup_bloom(sd_bus_message *m, struct kdbus_bloom_filter *bloom) {
+        void *data;
         unsigned i;
         int r;
 
         assert(m);
         assert(bloom);
 
-        memset(bloom, 0, BLOOM_SIZE);
+        data = bloom->data;
+        memzero(data, m->bus->bloom_size);
+        bloom->generation = 0;
 
-        bloom_add_pair(bloom, "message-type", bus_message_type_to_string(m->header->type));
+        bloom_add_pair(data, m->bus->bloom_size, m->bus->bloom_n_hash, "message-type", bus_message_type_to_string(m->header->type));
 
         if (m->interface)
-                bloom_add_pair(bloom, "interface", m->interface);
+                bloom_add_pair(data, m->bus->bloom_size, m->bus->bloom_n_hash, "interface", m->interface);
         if (m->member)
-                bloom_add_pair(bloom, "member", m->member);
+                bloom_add_pair(data, m->bus->bloom_size, m->bus->bloom_n_hash, "member", m->member);
         if (m->path) {
-                bloom_add_pair(bloom, "path", m->path);
-                bloom_add_pair(bloom, "path-slash-prefix", m->path);
-                bloom_add_prefixes(bloom, "path-slash-prefix", m->path, '/');
+                bloom_add_pair(data, m->bus->bloom_size, m->bus->bloom_n_hash, "path", m->path);
+                bloom_add_pair(data, m->bus->bloom_size, m->bus->bloom_n_hash, "path-slash-prefix", m->path);
+                bloom_add_prefixes(data, m->bus->bloom_size, m->bus->bloom_n_hash, "path-slash-prefix", m->path, '/');
         }
 
         r = sd_bus_message_rewind(m, true);
@@ -183,12 +188,12 @@ static int bus_message_setup_bloom(sd_bus_message *m, void *bloom) {
                 }
 
                 *e = 0;
-                bloom_add_pair(bloom, buf, t);
+                bloom_add_pair(data, m->bus->bloom_size, m->bus->bloom_n_hash, buf, t);
 
                 strcpy(e, "-dot-prefix");
-                bloom_add_prefixes(bloom, buf, t, '.');
+                bloom_add_prefixes(data, m->bus->bloom_size, m->bus->bloom_n_hash, buf, t, '.');
                 strcpy(e, "-slash-prefix");
-                bloom_add_prefixes(bloom, buf, t, '/');
+                bloom_add_prefixes(data, m->bus->bloom_size, m->bus->bloom_n_hash, buf, t, '/');
         }
 
         return 0;
@@ -231,7 +236,9 @@ static int bus_message_setup_kmsg(sd_bus *b, sd_bus_message *m) {
                 ALIGN8(offsetof(struct kdbus_item, vec) + sizeof(struct kdbus_vec));
 
         /* Add space for bloom filter */
-        sz += ALIGN8(offsetof(struct kdbus_item, data) + BLOOM_SIZE);
+        sz += ALIGN8(offsetof(struct kdbus_item, bloom_filter) +
+                     offsetof(struct kdbus_bloom_filter, data) +
+                     m->bus->bloom_size);
 
         /* Add in well-known destination header */
         if (well_known) {
@@ -250,7 +257,7 @@ static int bus_message_setup_kmsg(sd_bus *b, sd_bus_message *m) {
         }
 
         m->free_kdbus = true;
-        memset(m->kdbus, 0, sz);
+        memzero(m->kdbus, sz);
 
         m->kdbus->flags =
                 ((m->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED) ? 0 : KDBUS_MSG_FLAGS_EXPECT_REPLY) |
@@ -259,7 +266,8 @@ static int bus_message_setup_kmsg(sd_bus *b, sd_bus_message *m) {
                 well_known ? 0 :
                 m->destination ? unique : KDBUS_DST_ID_BROADCAST;
         m->kdbus->payload_type = KDBUS_PAYLOAD_DBUS;
-        m->kdbus->cookie = m->header->serial;
+        m->kdbus->cookie = (uint64_t) m->header->serial;
+        m->kdbus->priority = m->priority;
 
         if (m->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED)
                 m->kdbus->cookie_reply = m->reply_cookie;
@@ -292,8 +300,8 @@ static int bus_message_setup_kmsg(sd_bus *b, sd_bus_message *m) {
                         continue;
                 }
 
-                /* Otherwise let's send a vector to the actual data,
-                 * for that we need to map it first. */
+                /* Otherwise, let's send a vector to the actual data.
+                 * For that, we need to map it first. */
                 r = bus_body_part_map(part);
                 if (r < 0)
                         goto fail;
@@ -302,10 +310,10 @@ static int bus_message_setup_kmsg(sd_bus *b, sd_bus_message *m) {
         }
 
         if (m->kdbus->dst_id == KDBUS_DST_ID_BROADCAST) {
-                void *p;
+                struct kdbus_bloom_filter *bloom;
 
-                p = append_bloom(&d, BLOOM_SIZE);
-                r = bus_message_setup_bloom(m, p);
+                bloom = append_bloom(&d, m->bus->bloom_size);
+                r = bus_message_setup_bloom(m, bloom);
                 if (r < 0)
                         goto fail;
         }
@@ -500,9 +508,13 @@ static int bus_kernel_make_message(sd_bus *bus, struct kdbus_msg *k) {
                         break;
 
                 case KDBUS_ITEM_TIMESTAMP:
-                        m->realtime = d->timestamp.realtime_ns / NSEC_PER_USEC;
-                        m->monotonic = d->timestamp.monotonic_ns / NSEC_PER_USEC;
-                        m->seqnum = d->timestamp.seqnum;
+
+                        if (bus->attach_flags & KDBUS_ATTACH_TIMESTAMP) {
+                                m->realtime = d->timestamp.realtime_ns / NSEC_PER_USEC;
+                                m->monotonic = d->timestamp.monotonic_ns / NSEC_PER_USEC;
+                                m->seqnum = d->timestamp.seqnum;
+                        }
+
                         break;
 
                 case KDBUS_ITEM_PID_COMM:
@@ -568,6 +580,11 @@ static int bus_kernel_make_message(sd_bus *bus, struct kdbus_msg *k) {
                                 goto fail;
                         break;
 
+                case KDBUS_ITEM_CONN_NAME:
+                        m->creds.conn_name = d->str;
+                        m->creds.mask |= SD_BUS_CREDS_CONNECTION_NAME & bus->creds_mask;
+                        break;
+
                 case KDBUS_ITEM_FDS:
                 case KDBUS_ITEM_SECLABEL:
                         break;
@@ -642,7 +659,7 @@ int bus_kernel_take_fd(sd_bus *b) {
         b->use_memfd = 1;
 
         if (b->connection_name) {
-                g = sd_bus_label_escape(b->connection_name);
+                g = bus_label_escape(b->connection_name);
                 if (!g)
                         return -ENOMEM;
 
@@ -662,7 +679,7 @@ int bus_kernel_take_fd(sd_bus *b) {
                 } else {
                         _cleanup_free_ char *e = NULL;
 
-                        e = sd_bus_label_escape(pr);
+                        e = bus_label_escape(pr);
                         if (!e)
                                 return -ENOMEM;
 
@@ -675,7 +692,7 @@ int bus_kernel_take_fd(sd_bus *b) {
                         name = g;
                 }
 
-                b->connection_name = sd_bus_label_unescape(name);
+                b->connection_name = bus_label_unescape(name);
                 if (!b->connection_name)
                         return -ENOMEM;
         }
@@ -738,9 +755,12 @@ int bus_kernel_take_fd(sd_bus *b) {
             hello->conn_flags > 0xFFFFFFFFULL)
                 return -ENOTSUP;
 
-        if (hello->bloom_size != BLOOM_SIZE)
+        if (!bloom_validate_parameters((size_t) hello->bloom.size, (unsigned) hello->bloom.n_hash))
                 return -ENOTSUP;
 
+        b->bloom_size = (size_t) hello->bloom.size;
+        b->bloom_n_hash = (unsigned) hello->bloom.n_hash;
+
         if (asprintf(&b->unique_name, ":1.%llu", (unsigned long long) hello->id) < 0)
                 return -ENOMEM;
 
@@ -791,7 +811,7 @@ static void close_kdbus_msg(sd_bus *bus, struct kdbus_msg *k) {
                 if (d->type == KDBUS_ITEM_FDS)
                         close_many(d->fds, (d->size - offsetof(struct kdbus_item, fds)) / sizeof(int));
                 else if (d->type == KDBUS_ITEM_PAYLOAD_MEMFD)
-                        close_nointr_nofail(d->memfd.fd);
+                        safe_close(d->memfd.fd);
         }
 }
 
@@ -901,10 +921,10 @@ static int push_name_owner_changed(sd_bus *bus, const char *name, const char *ol
 
         r = sd_bus_message_new_signal(
                         bus,
+                        &m,
                         "/org/freedesktop/DBus",
                         "org.freedesktop.DBus",
-                        "NameOwnerChanged",
-                        &m);
+                        "NameOwnerChanged");
         if (r < 0)
                 return r;
 
@@ -1029,7 +1049,7 @@ static int bus_kernel_translate_message(sd_bus *bus, struct kdbus_msg *k) {
         return translate[found->type - _KDBUS_ITEM_KERNEL_BASE](bus, k, found);
 }
 
-int bus_kernel_read_message(sd_bus *bus) {
+int bus_kernel_read_message(sd_bus *bus, bool hint_priority, int64_t priority) {
         struct kdbus_cmd_recv recv = {};
         struct kdbus_msg *k;
         int r;
@@ -1040,6 +1060,11 @@ int bus_kernel_read_message(sd_bus *bus) {
         if (r < 0)
                 return r;
 
+        if (hint_priority) {
+                recv.flags |= KDBUS_RECV_USE_PRIORITY;
+                recv.priority = priority;
+        }
+
         r = ioctl(bus->input_fd, KDBUS_CMD_MSG_RECV, &recv);
         if (r < 0) {
                 if (errno == EAGAIN)
@@ -1095,7 +1120,7 @@ int bus_kernel_pop_memfd(sd_bus *bus, void **address, size_t *mapped, size_t *al
 
                 assert(bus->connection_name);
 
-                g = sd_bus_label_escape(bus->connection_name);
+                g = bus_label_escape(bus->connection_name);
                 if (!g)
                         return -ENOMEM;
 
@@ -1140,7 +1165,7 @@ static void close_and_munmap(int fd, void *address, size_t size) {
         if (size > 0)
                 assert_se(munmap(address, PAGE_ALIGN(size)) >= 0);
 
-        close_nointr_nofail(fd);
+        safe_close(fd);
 }
 
 void bus_kernel_push_memfd(sd_bus *bus, int fd, void *address, size_t mapped, size_t allocated) {
@@ -1240,6 +1265,9 @@ int kdbus_translate_attach_flags(uint64_t mask, uint64_t *kdbus_mask) {
         if (mask & SD_BUS_CREDS_WELL_KNOWN_NAMES)
                 m |= KDBUS_ATTACH_NAMES;
 
+        if (mask & SD_BUS_CREDS_CONNECTION_NAME)
+                m |= KDBUS_ATTACH_CONN_NAME;
+
         *kdbus_mask = m;
         return 0;
 }
@@ -1264,29 +1292,35 @@ int bus_kernel_create_bus(const char *name, bool world, char **s) {
         make->size = offsetof(struct kdbus_cmd_make, items);
 
         n = make->items;
-        n->size = offsetof(struct kdbus_item, data64) + sizeof(uint64_t);
-        n->type = KDBUS_ITEM_BLOOM_SIZE;
-        n->data64[0] = BLOOM_SIZE;
-        assert_cc(BLOOM_SIZE % 8 == 0);
+        n->size = offsetof(struct kdbus_item, bloom_parameter) +
+                  sizeof(struct kdbus_bloom_parameter);
+        n->type = KDBUS_ITEM_BLOOM_PARAMETER;
+
+        n->bloom_parameter.size = DEFAULT_BLOOM_SIZE;
+        n->bloom_parameter.n_hash = DEFAULT_BLOOM_N_HASH;
+
+        assert_cc(DEFAULT_BLOOM_SIZE > 0);
+        assert_cc(DEFAULT_BLOOM_N_HASH > 0);
+
         make->size += ALIGN8(n->size);
 
         n = KDBUS_ITEM_NEXT(n);
-        sprintf(n->str, "%lu-%s", (unsigned long) getuid(), name);
+        sprintf(n->str, UID_FMT "-%s", getuid(), name);
         n->size = offsetof(struct kdbus_item, str) + strlen(n->str) + 1;
         n->type = KDBUS_ITEM_MAKE_NAME;
         make->size += ALIGN8(n->size);
 
-        make->flags = KDBUS_MAKE_POLICY_OPEN | (world ? KDBUS_MAKE_ACCESS_WORLD : 0);
+        make->flags = world ? KDBUS_MAKE_ACCESS_WORLD : 0;
 
         if (ioctl(fd, KDBUS_CMD_BUS_MAKE, make) < 0) {
-                close_nointr_nofail(fd);
+                safe_close(fd);
                 return -errno;
         }
 
         /* The higher 32bit of the flags field are considered
          * 'incompatible flags'. Refuse them all for now. */
         if (make->flags > 0xFFFFFFFFULL) {
-                close_nointr_nofail(fd);
+                safe_close(fd);
                 return -ENOTSUP;
         }
 
@@ -1295,7 +1329,7 @@ int bus_kernel_create_bus(const char *name, bool world, char **s) {
 
                 p = strjoin("/dev/kdbus/", n->str, "/bus", NULL);
                 if (!p) {
-                        close_nointr_nofail(fd);
+                        safe_close(fd);
                         return -ENOMEM;
                 }
 
@@ -1305,57 +1339,169 @@ int bus_kernel_create_bus(const char *name, bool world, char **s) {
         return fd;
 }
 
-int bus_kernel_create_starter(const char *bus, const char *name) {
-        struct kdbus_cmd_hello *hello;
-        struct kdbus_item *n;
+static int bus_kernel_translate_access(BusNamePolicyAccess access) {
+        assert(access >= 0);
+        assert(access < _BUSNAME_POLICY_ACCESS_MAX);
+
+        switch (access) {
+
+        case BUSNAME_POLICY_ACCESS_SEE:
+                return KDBUS_POLICY_SEE;
+
+        case BUSNAME_POLICY_ACCESS_TALK:
+                return KDBUS_POLICY_TALK;
+
+        case BUSNAME_POLICY_ACCESS_OWN:
+                return KDBUS_POLICY_OWN;
+
+        default:
+                assert_not_reached("Unknown policy access");
+        }
+}
+
+static int bus_kernel_translate_policy(const BusNamePolicy *policy, struct kdbus_item *item) {
+        int r;
+
+        assert(policy);
+        assert(item);
+
+        switch (policy->type) {
+
+        case BUSNAME_POLICY_TYPE_USER: {
+                const char *user = policy->name;
+                uid_t uid;
+
+                r = get_user_creds(&user, &uid, NULL, NULL, NULL);
+                if (r < 0)
+                        return r;
+
+                item->policy_access.type = KDBUS_POLICY_ACCESS_USER;
+                item->policy_access.id = uid;
+                break;
+        }
+
+        case BUSNAME_POLICY_TYPE_GROUP: {
+                const char *group = policy->name;
+                gid_t gid;
+
+                r = get_group_creds(&group, &gid);
+                if (r < 0)
+                        return r;
+
+                item->policy_access.type = KDBUS_POLICY_ACCESS_GROUP;
+                item->policy_access.id = gid;
+                break;
+        }
+
+        default:
+                assert_not_reached("Unknown policy type");
+        }
+
+        item->policy_access.access = bus_kernel_translate_access(policy->access);
+
+        return 0;
+}
+
+int bus_kernel_open_bus_fd(const char *bus, char **path) {
         char *p;
         int fd;
+        size_t len;
 
-        assert(bus);
-        assert(name);
+        len = strlen("/dev/kdbus/") + DECIMAL_STR_MAX(uid_t) + 1 + strlen(bus) + strlen("/bus") + 1;
 
-        p = alloca(sizeof("/dev/kdbus/") - 1 + DECIMAL_STR_MAX(uid_t) + 1 + strlen(bus) + sizeof("/bus"));
-        sprintf(p, "/dev/kdbus/%lu-%s/bus", (unsigned long) getuid(), bus);
+        if (path) {
+                p = malloc(len);
+                if (!p)
+                        return -ENOMEM;
+                *path = p;
+        } else
+                p = alloca(len);
+        sprintf(p, "/dev/kdbus/" UID_FMT "-%s/bus", getuid(), bus);
 
         fd = open(p, O_RDWR|O_NOCTTY|O_CLOEXEC);
         if (fd < 0)
                 return -errno;
 
-        hello = alloca0(ALIGN8(offsetof(struct kdbus_cmd_hello, items) +
-                               offsetof(struct kdbus_item, str) +
-                               strlen(name) + 1));
+        return fd;
+}
+
+int bus_kernel_make_starter(
+                int fd,
+                const char *name,
+                bool activating,
+                bool accept_fd,
+                BusNamePolicy *policy,
+                BusNamePolicyAccess world_policy) {
+
+        struct kdbus_cmd_hello *hello;
+        struct kdbus_item *n;
+        size_t policy_cnt = 0;
+        BusNamePolicy *po;
+        size_t size;
+        int r;
+
+        assert(fd >= 0);
+        assert(name);
+
+        LIST_FOREACH(policy, po, policy)
+                policy_cnt++;
+
+        if (world_policy >= 0)
+                policy_cnt++;
+
+        size = ALIGN8(offsetof(struct kdbus_cmd_hello, items)) +
+               ALIGN8(offsetof(struct kdbus_item, str) + strlen(name) + 1) +
+               policy_cnt * ALIGN8(offsetof(struct kdbus_item, policy_access) + sizeof(struct kdbus_policy_access));
+
+        hello = alloca0(size);
 
         n = hello->items;
         strcpy(n->str, name);
         n->size = offsetof(struct kdbus_item, str) + strlen(n->str) + 1;
         n->type = KDBUS_ITEM_NAME;
+        n = KDBUS_ITEM_NEXT(n);
 
-        hello->size = ALIGN8(offsetof(struct kdbus_cmd_hello, items) + n->size);
-        hello->conn_flags = KDBUS_HELLO_ACTIVATOR;
+        LIST_FOREACH(policy, po, policy) {
+                n->type = KDBUS_ITEM_POLICY_ACCESS;
+                n->size = offsetof(struct kdbus_item, policy_access) + sizeof(struct kdbus_policy_access);
+
+                r = bus_kernel_translate_policy(po, n);
+                if (r < 0)
+                        return r;
+
+                n = KDBUS_ITEM_NEXT(n);
+        }
+
+        if (world_policy >= 0) {
+                n->type = KDBUS_ITEM_POLICY_ACCESS;
+                n->size = offsetof(struct kdbus_item, policy_access) + sizeof(struct kdbus_policy_access);
+                n->policy_access.type = KDBUS_POLICY_ACCESS_WORLD;
+                n->policy_access.access = bus_kernel_translate_access(world_policy);
+        }
+
+        hello->size = size;
+        hello->conn_flags =
+                (activating ? KDBUS_HELLO_ACTIVATOR : KDBUS_HELLO_POLICY_HOLDER) |
+                (accept_fd ? KDBUS_HELLO_ACCEPT_FD : 0);
         hello->pool_size = KDBUS_POOL_SIZE;
+        hello->attach_flags = _KDBUS_ATTACH_ALL;
 
-        if (ioctl(fd, KDBUS_CMD_HELLO, hello) < 0) {
-                close_nointr_nofail(fd);
+        if (ioctl(fd, KDBUS_CMD_HELLO, hello) < 0)
                 return -errno;
-        }
 
         /* The higher 32bit of both flags fields are considered
          * 'incompatible flags'. Refuse them all for now. */
         if (hello->bus_flags > 0xFFFFFFFFULL ||
-            hello->conn_flags > 0xFFFFFFFFULL) {
-                close_nointr_nofail(fd);
+            hello->conn_flags > 0xFFFFFFFFULL)
                 return -ENOTSUP;
-        }
 
-        if (hello->bloom_size != BLOOM_SIZE) {
-                close_nointr_nofail(fd);
+        if (!bloom_validate_parameters((size_t) hello->bloom.size, (unsigned) hello->bloom.n_hash))
                 return -ENOTSUP;
-        }
 
         return fd;
 }
 
-int bus_kernel_create_namespace(const char *name, char **s) {
+int bus_kernel_create_domain(const char *name, char **s) {
         struct kdbus_cmd_make *make;
         struct kdbus_item *n;
         int fd;
@@ -1377,26 +1523,26 @@ int bus_kernel_create_namespace(const char *name, char **s) {
         n->type = KDBUS_ITEM_MAKE_NAME;
 
         make->size = ALIGN8(offsetof(struct kdbus_cmd_make, items) + n->size);
-        make->flags = KDBUS_MAKE_POLICY_OPEN | KDBUS_MAKE_ACCESS_WORLD;
+        make->flags = KDBUS_MAKE_ACCESS_WORLD;
 
-        if (ioctl(fd, KDBUS_CMD_NS_MAKE, make) < 0) {
-                close_nointr_nofail(fd);
+        if (ioctl(fd, KDBUS_CMD_DOMAIN_MAKE, make) < 0) {
+                safe_close(fd);
                 return -errno;
         }
 
         /* The higher 32bit of the flags field are considered
          * 'incompatible flags'. Refuse them all for now. */
         if (make->flags > 0xFFFFFFFFULL) {
-                close_nointr_nofail(fd);
+                safe_close(fd);
                 return -ENOTSUP;
         }
 
         if (s) {
                 char *p;
 
-                p = strappend("/dev/kdbus/ns/", name);
+                p = strappend("/dev/kdbus/domain/", name);
                 if (!p) {
-                        close_nointr_nofail(fd);
+                        safe_close(fd);
                         return -ENOMEM;
                 }
 
@@ -1408,17 +1554,13 @@ int bus_kernel_create_namespace(const char *name, char **s) {
 
 int bus_kernel_create_monitor(const char *bus) {
         struct kdbus_cmd_hello *hello;
-        char *p;
         int fd;
 
         assert(bus);
 
-        p = alloca(sizeof("/dev/kdbus/") - 1 + DECIMAL_STR_MAX(uid_t) + 1 + strlen(bus) + sizeof("/bus"));
-        sprintf(p, "/dev/kdbus/%lu-%s/bus", (unsigned long) getuid(), bus);
-
-        fd = open(p, O_RDWR|O_NOCTTY|O_CLOEXEC);
+        fd = bus_kernel_open_bus_fd(bus, NULL);
         if (fd < 0)
-                return -errno;
+                return fd;
 
         hello = alloca0(sizeof(struct kdbus_cmd_hello));
         hello->size = sizeof(struct kdbus_cmd_hello);
@@ -1426,7 +1568,7 @@ int bus_kernel_create_monitor(const char *bus) {
         hello->pool_size = KDBUS_POOL_SIZE;
 
         if (ioctl(fd, KDBUS_CMD_HELLO, hello) < 0) {
-                close_nointr_nofail(fd);
+                safe_close(fd);
                 return -errno;
         }
 
@@ -1434,7 +1576,7 @@ int bus_kernel_create_monitor(const char *bus) {
          * 'incompatible flags'. Refuse them all for now. */
         if (hello->bus_flags > 0xFFFFFFFFULL ||
             hello->conn_flags > 0xFFFFFFFFULL) {
-                close_nointr_nofail(fd);
+                safe_close(fd);
                 return -ENOTSUP;
         }
 
@@ -1450,3 +1592,16 @@ int bus_kernel_try_close(sd_bus *bus) {
 
         return 0;
 }
+
+int bus_kernel_drop_one(int fd) {
+        struct kdbus_cmd_recv recv = {
+                .flags = KDBUS_RECV_DROP
+        };
+
+        assert(fd >= 0);
+
+        if (ioctl(fd, KDBUS_CMD_MSG_RECV, &recv) < 0)
+                return -errno;
+
+        return 0;
+}