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authorDavid Herrmann <dh.herrmann@gmail.com>2015-07-16 15:14:43 +0200
committerDavid Herrmann <dh.herrmann@gmail.com>2015-07-16 16:36:35 +0200
commite23bc0e7cac8ba79f4e14ab98ecd68c79cc87aab (patch)
treeb16aaccf677c04381bb37ef72d5a21e690308185
parent2ec7c4279e4cbbe668c5dfb0ab447b74deaa294b (diff)
bus-proxy: never pass on unmatched broadcasts
The lovely libvirtd goes into crazy mode if it receives broadcasts that it didn't subscribe to. With bus-proxyd, this might happen in 2 cases: 1) The kernel passes us an unmatched signal due to a false-positive bloom-match. 2) We generate NameOwnerChanged/NameAcquired/NameLost locally even though the peer didn't subscribe to it. dbus-daemon is reliable in what signals it passes on. So make sure we follow that style. Never ever send a signal to a local peer if it doesn't match an installed filter of that peer.
-rw-r--r--src/bus-proxyd/driver.c5
-rw-r--r--src/bus-proxyd/driver.h3
-rw-r--r--src/bus-proxyd/proxy.c55
-rw-r--r--src/bus-proxyd/proxy.h3
-rw-r--r--src/bus-proxyd/synthesize.c19
-rw-r--r--src/bus-proxyd/synthesize.h3
6 files changed, 75 insertions, 13 deletions
diff --git a/src/bus-proxyd/driver.c b/src/bus-proxyd/driver.c
index 4ac955da41..1cb5ea5008 100644
--- a/src/bus-proxyd/driver.c
+++ b/src/bus-proxyd/driver.c
@@ -33,6 +33,7 @@
#include "strv.h"
#include "set.h"
#include "driver.h"
+#include "proxy.h"
#include "synthesize.h"
static int get_creds_by_name(sd_bus *bus, const char *name, uint64_t mask, sd_bus_creds **_creds, sd_bus_error *error) {
@@ -70,7 +71,7 @@ static int get_creds_by_message(sd_bus *bus, sd_bus_message *m, uint64_t mask, s
return get_creds_by_name(bus, name, mask, _creds, error);
}
-int bus_proxy_process_driver(sd_bus *a, sd_bus *b, sd_bus_message *m, SharedPolicy *sp, const struct ucred *ucred, Set *owned_names) {
+int bus_proxy_process_driver(Proxy *p, sd_bus *a, sd_bus *b, sd_bus_message *m, SharedPolicy *sp, const struct ucred *ucred, Set *owned_names) {
int r;
assert(a);
@@ -189,7 +190,7 @@ int bus_proxy_process_driver(sd_bus *a, sd_bus *b, sd_bus_message *m, SharedPoli
if (r < 0)
return synthetic_reply_method_errno(m, r, NULL);
- r = sd_bus_add_match(a, NULL, match, NULL, NULL);
+ r = sd_bus_add_match(a, NULL, match, proxy_match, p);
if (r < 0)
return synthetic_reply_method_errno(m, r, NULL);
diff --git a/src/bus-proxyd/driver.h b/src/bus-proxyd/driver.h
index b8cedf5ce5..da3834f8b0 100644
--- a/src/bus-proxyd/driver.h
+++ b/src/bus-proxyd/driver.h
@@ -23,5 +23,6 @@
#include "sd-bus.h"
#include "bus-xml-policy.h"
+#include "proxy.h"
-int bus_proxy_process_driver(sd_bus *a, sd_bus *b, sd_bus_message *m, SharedPolicy *sp, const struct ucred *ucred, Set *owned_names);
+int bus_proxy_process_driver(Proxy *p, sd_bus *a, sd_bus *b, sd_bus_message *m, SharedPolicy *sp, const struct ucred *ucred, Set *owned_names);
diff --git a/src/bus-proxyd/proxy.c b/src/bus-proxyd/proxy.c
index 189ee969c7..89c68134fc 100644
--- a/src/bus-proxyd/proxy.c
+++ b/src/bus-proxyd/proxy.c
@@ -144,9 +144,17 @@ static int proxy_create_local(Proxy *p, int in_fd, int out_fd, bool negotiate_fd
return 0;
}
+static int proxy_match_synthetic(sd_bus_message *m, void *userdata, sd_bus_error *error) {
+ Proxy *p = userdata;
+
+ p->synthetic_matched = true;
+ return 0; /* make sure to continue processing it in further handlers */
+}
+
/*
- * dbus-1 clients receive NameOwnerChanged and directed signals without
- * subscribing to them; install the matches to receive them on kdbus.
+ * We always need NameOwnerChanged so we can synthesize NameLost and
+ * NameAcquired. Furthermore, dbus-1 always passes unicast-signals through, so
+ * subscribe unconditionally.
*/
static int proxy_prepare_matches(Proxy *p) {
_cleanup_free_ char *match = NULL;
@@ -172,7 +180,7 @@ static int proxy_prepare_matches(Proxy *p) {
if (!match)
return log_oom();
- r = sd_bus_add_match(p->destination_bus, NULL, match, NULL, NULL);
+ r = sd_bus_add_match(p->destination_bus, NULL, match, proxy_match_synthetic, p);
if (r < 0)
return log_error_errno(r, "Failed to add match for NameLost: %m");
@@ -189,7 +197,7 @@ static int proxy_prepare_matches(Proxy *p) {
if (!match)
return log_oom();
- r = sd_bus_add_match(p->destination_bus, NULL, match, NULL, NULL);
+ r = sd_bus_add_match(p->destination_bus, NULL, match, proxy_match_synthetic, p);
if (r < 0)
return log_error_errno(r, "Failed to add match for NameAcquired: %m");
@@ -202,7 +210,7 @@ static int proxy_prepare_matches(Proxy *p) {
if (!match)
return log_oom();
- r = sd_bus_add_match(p->destination_bus, NULL, match, NULL, NULL);
+ r = sd_bus_add_match(p->destination_bus, NULL, match, proxy_match_synthetic, p);
if (r < 0)
log_error_errno(r, "Failed to add match for directed signals: %m");
/* FIXME: temporarily ignore error to support older kdbus versions */
@@ -679,11 +687,28 @@ static int patch_sender(sd_bus *a, sd_bus_message *m) {
static int proxy_process_destination_to_local(Proxy *p) {
_cleanup_bus_message_unref_ sd_bus_message *m = NULL;
+ bool matched, matched_synthetic;
int r;
assert(p);
+ /*
+ * Usually, we would just take any message that the bus passes to us
+ * and forward it to the local connection. However, there are actually
+ * applications that fail if they receive broadcasts that they didn't
+ * subscribe to. Therefore, we actually emulate a real broadcast
+ * matching here, and discard any broadcasts that weren't matched. Our
+ * match-handlers remembers whether a message was matched by any rule,
+ * by marking it in @p->message_matched.
+ */
+
r = sd_bus_process(p->destination_bus, &m);
+
+ matched = p->message_matched;
+ matched_synthetic = p->synthetic_matched;
+ p->message_matched = false;
+ p->synthetic_matched = false;
+
if (r == -ECONNRESET || r == -ENOTCONN) /* Treat 'connection reset by peer' as clean exit condition */
return r;
if (r < 0) {
@@ -699,12 +724,21 @@ static int proxy_process_destination_to_local(Proxy *p) {
if (sd_bus_message_is_signal(m, "org.freedesktop.DBus.Local", "Disconnected"))
return -ECONNRESET;
- r = synthesize_name_acquired(p->destination_bus, p->local_bus, m);
+ r = synthesize_name_acquired(p, p->destination_bus, p->local_bus, m);
if (r == -ECONNRESET || r == -ENOTCONN)
return r;
if (r < 0)
return log_error_errno(r, "Failed to synthesize message: %m");
+ /* discard broadcasts that were not matched by any MATCH rule */
+ if (!matched && !sd_bus_message_get_destination(m)) {
+ if (!matched_synthetic)
+ log_warning("Dropped unmatched broadcast: uid=" UID_FMT " gid=" GID_FMT" message=%s path=%s interface=%s member=%s",
+ p->local_creds.uid, p->local_creds.gid, bus_message_type_to_string(m->header->type),
+ strna(m->path), strna(m->interface), strna(m->member));
+ return 1;
+ }
+
patch_sender(p->destination_bus, m);
if (p->policy) {
@@ -788,7 +822,7 @@ static int proxy_process_local_to_destination(Proxy *p) {
if (r > 0)
return 1;
- r = bus_proxy_process_driver(p->destination_bus, p->local_bus, m, p->policy, &p->local_creds, p->owned_names);
+ r = bus_proxy_process_driver(p, p->destination_bus, p->local_bus, m, p->policy, &p->local_creds, p->owned_names);
if (r == -ECONNRESET || r == -ENOTCONN)
return r;
if (r < 0)
@@ -834,6 +868,13 @@ static int proxy_process_local_to_destination(Proxy *p) {
return 1;
}
+int proxy_match(sd_bus_message *m, void *userdata, sd_bus_error *error) {
+ Proxy *p = userdata;
+
+ p->message_matched = true;
+ return 0; /* make sure to continue processing it in further handlers */
+}
+
int proxy_run(Proxy *p) {
int r;
diff --git a/src/bus-proxyd/proxy.h b/src/bus-proxyd/proxy.h
index ff278a2465..ccb951c109 100644
--- a/src/bus-proxyd/proxy.h
+++ b/src/bus-proxyd/proxy.h
@@ -39,6 +39,8 @@ struct Proxy {
bool got_hello : 1;
bool queue_overflow : 1;
+ bool message_matched : 1;
+ bool synthetic_matched : 1;
};
int proxy_new(Proxy **out, int in_fd, int out_fd, const char *dest);
@@ -46,6 +48,7 @@ Proxy *proxy_free(Proxy *p);
int proxy_set_policy(Proxy *p, SharedPolicy *policy, char **configuration);
int proxy_hello_policy(Proxy *p, uid_t original_uid);
+int proxy_match(sd_bus_message *m, void *userdata, sd_bus_error *error);
int proxy_run(Proxy *p);
DEFINE_TRIVIAL_CLEANUP_FUNC(Proxy*, proxy_free);
diff --git a/src/bus-proxyd/synthesize.c b/src/bus-proxyd/synthesize.c
index 67bcc7a242..3ecedfd575 100644
--- a/src/bus-proxyd/synthesize.c
+++ b/src/bus-proxyd/synthesize.c
@@ -28,6 +28,7 @@
#include "bus-internal.h"
#include "bus-message.h"
#include "bus-util.h"
+#include "bus-match.h"
#include "synthesize.h"
int synthetic_driver_send(sd_bus *b, sd_bus_message *m) {
@@ -152,11 +153,12 @@ int synthetic_reply_method_return_strv(sd_bus_message *call, char **l) {
return synthetic_driver_send(call->bus, m);
}
-int synthesize_name_acquired(sd_bus *a, sd_bus *b, sd_bus_message *m) {
+int synthesize_name_acquired(Proxy *p, sd_bus *a, sd_bus *b, sd_bus_message *m) {
_cleanup_bus_message_unref_ sd_bus_message *n = NULL;
const char *name, *old_owner, *new_owner;
int r;
+ assert(p);
assert(a);
assert(b);
assert(m);
@@ -216,5 +218,18 @@ int synthesize_name_acquired(sd_bus *a, sd_bus *b, sd_bus_message *m) {
if (r < 0)
return r;
- return sd_bus_send(b, n, NULL);
+ /*
+ * Make sure to only forward NameLost/NameAcquired messages if they
+ * match an installed MATCH rule of the local client. We really must
+ * not send messages the client doesn't expect.
+ */
+
+ r = bus_match_run(b, &b->match_callbacks, n);
+ if (r >= 0 && p->message_matched)
+ r = sd_bus_send(b, n, NULL);
+
+ p->message_matched = false;
+ p->synthetic_matched = false;
+
+ return r;
}
diff --git a/src/bus-proxyd/synthesize.h b/src/bus-proxyd/synthesize.h
index e850350bc5..b596daddf2 100644
--- a/src/bus-proxyd/synthesize.h
+++ b/src/bus-proxyd/synthesize.h
@@ -22,6 +22,7 @@
***/
#include "sd-bus.h"
+#include "proxy.h"
int synthetic_driver_send(sd_bus *b, sd_bus_message *m);
@@ -33,4 +34,4 @@ int synthetic_reply_method_errorf(sd_bus_message *call, const char *name, const
int synthetic_reply_method_errno(sd_bus_message *call, int error, const sd_bus_error *p);
int synthetic_reply_method_errnof(sd_bus_message *call, int error, const char *format, ...) _sd_printf_(3, 4);
-int synthesize_name_acquired(sd_bus *a, sd_bus *b, sd_bus_message *m);
+int synthesize_name_acquired(Proxy *p, sd_bus *a, sd_bus *b, sd_bus_message *m);