bus: rework bloom filter logic to operate with variable bloom filter

sizes and numbers of hash functions

In order to make the bloom filter logic more future proof communicate
bloom filter parameters from the original bus creator to the clients,
and allow them to be variable within certain ranges.

1 files changed, 24 insertions, 17 deletions

diff --git a/src/libsystemd/sd-bus/bus-kernel.c b/src/libsystemd/sd-bus/bus-kernel.c
index b46cada648..0b5bae32d5 100644
--- a/src/libsystemd/sd-bus/bus-kernel.c
+++ b/src/libsystemd/sd-bus/bus-kernel.c
@@ -140,19 +140,19 @@ static int bus_message_setup_bloom(sd_bus_message *m, struct kdbus_bloom_filter
         assert(bloom);
 
         data = bloom->data;
-        memset(data, 0, BLOOM_SIZE);
+        memset(data, 0, m->bus->bloom_size);
         bloom->generation = 0;
 
-        bloom_add_pair(data, "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(data, "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(data, "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(data, "path", m->path);
-                bloom_add_pair(data, "path-slash-prefix", m->path);
-                bloom_add_prefixes(data, "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);
@@ -187,12 +187,12 @@ static int bus_message_setup_bloom(sd_bus_message *m, struct kdbus_bloom_filter
                 }
 
                 *e = 0;
-                bloom_add_pair(data, buf, t);
+                bloom_add_pair(data, m->bus->bloom_size, m->bus->bloom_n_hash, buf, t);
 
                 strcpy(e, "-dot-prefix");
-                bloom_add_prefixes(data, buf, t, '.');
+                bloom_add_prefixes(data, m->bus->bloom_size, m->bus->bloom_n_hash, buf, t, '.');
                 strcpy(e, "-slash-prefix");
-                bloom_add_prefixes(data, buf, t, '/');
+                bloom_add_prefixes(data, m->bus->bloom_size, m->bus->bloom_n_hash, buf, t, '/');
         }
 
         return 0;
@@ -237,7 +237,7 @@ static int bus_message_setup_kmsg(sd_bus *b, sd_bus_message *m) {
         /* Add space for bloom filter */
         sz += ALIGN8(offsetof(struct kdbus_item, bloom_filter) +
                      offsetof(struct kdbus_bloom_filter, data) +
-                     BLOOM_SIZE);
+                     m->bus->bloom_size);
 
         /* Add in well-known destination header */
         if (well_known) {
@@ -311,7 +311,7 @@ static int bus_message_setup_kmsg(sd_bus *b, sd_bus_message *m) {
         if (m->kdbus->dst_id == KDBUS_DST_ID_BROADCAST) {
                 struct kdbus_bloom_filter *bloom;
 
-                bloom = append_bloom(&d, BLOOM_SIZE);
+                bloom = append_bloom(&d, m->bus->bloom_size);
                 r = bus_message_setup_bloom(m, bloom);
                 if (r < 0)
                         goto fail;
@@ -754,9 +754,12 @@ 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;
 
@@ -1291,9 +1294,13 @@ int bus_kernel_create_bus(const char *name, bool world, char **s) {
         n->size = offsetof(struct kdbus_item, bloom_parameter) +
                   sizeof(struct kdbus_bloom_parameter);
         n->type = KDBUS_ITEM_BLOOM_PARAMETER;
-        n->bloom_parameter.size = BLOOM_SIZE;
-        n->bloom_parameter.n_hash = 1;
-        assert_cc(BLOOM_SIZE % 8 == 0);
+
+        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);
@@ -1373,7 +1380,7 @@ int bus_kernel_create_starter(const char *bus, const char *name) {
                 return -ENOTSUP;
         }
 
-        if (hello->bloom.size != BLOOM_SIZE) {
+        if (!bloom_validate_parameters((size_t) hello->bloom.size, (unsigned) hello->bloom.n_hash)) {
                 close_nointr_nofail(fd);
                 return -ENOTSUP;
         }