[Qemu-devel] [PATCH v3 5/8] sockets: check that the named file descriptor is a socket

[Daniel P. Berrange]

The SocketAddress struct has an "fd" type, which references the name of a
file descriptor passed over the monitor using the "getfd" command. We
currently blindly assume the FD is a socket, which can lead to hard to
diagnose errors later. This adds an explicit check that the FD is actually
a socket to improve the error diagnosis.

Signed-off-by: Daniel P. Berrange <address@hidden>
---
 tests/.gitignore       |   1 +
 tests/Makefile.include |   3 ++
 tests/test-sockets.c   | 139 +++++++++++++++++++++++++++++++++++++++++++++++++
 util/qemu-sockets.c    |  18 ++++++-
 4 files changed, 159 insertions(+), 2 deletions(-)
 create mode 100644 tests/test-sockets.c

diff --git a/tests/.gitignore b/tests/.gitignore
index 74e55d7264..44be8c2c79 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -80,6 +80,7 @@ test-qobject-output-visitor
 test-rcu-list
 test-replication
 test-shift128
+test-sockets
 test-string-input-visitor
 test-string-output-visitor
 test-thread-pool
diff --git a/tests/Makefile.include b/tests/Makefile.include
index bede832dc1..2730f7562b 100644
--- a/tests/Makefile.include
+++ b/tests/Makefile.include
@@ -135,6 +135,7 @@ ifneq (,$(findstring qemu-ga,$(TOOLS)))
 check-unit-$(CONFIG_LINUX) += tests/test-qga$(EXESUF)
 endif
 check-unit-y += tests/test-timed-average$(EXESUF)
+check-unit-y += tests/test-sockets$(EXESUF)
 check-unit-y += tests/test-io-task$(EXESUF)
 check-unit-y += tests/test-io-channel-socket$(EXESUF)
 check-unit-y += tests/test-io-channel-file$(EXESUF)
@@ -694,6 +695,8 @@ tests/test-crypto-tlscredsx509$(EXESUF): 
tests/test-crypto-tlscredsx509.o \
 tests/test-crypto-tlssession.o-cflags := $(TASN1_CFLAGS)
 tests/test-crypto-tlssession$(EXESUF): tests/test-crypto-tlssession.o \
        tests/crypto-tls-x509-helpers.o tests/pkix_asn1_tab.o 
$(test-crypto-obj-y)
+tests/test-sockets$(EXESUF): tests/test-sockets.o tests/socket-helpers.o \
+       $(test-util-obj-y)
 tests/test-io-task$(EXESUF): tests/test-io-task.o $(test-io-obj-y)
 tests/test-io-channel-socket$(EXESUF): tests/test-io-channel-socket.o \
         tests/io-channel-helpers.o tests/socket-helpers.o $(test-io-obj-y)
diff --git a/tests/test-sockets.c b/tests/test-sockets.c
new file mode 100644
index 0000000000..8a2962fe7b
--- /dev/null
+++ b/tests/test-sockets.c
@@ -0,0 +1,139 @@
+/*
+ * Test core sockets APIs
+ *
+ * Copyright 2015-2018 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 or
+ * (at your option) version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+
+#include "qemu/osdep.h"
+#include "qemu/sockets.h"
+#include "socket-helpers.h"
+#include "qapi/error.h"
+#include "monitor/monitor.h"
+
+
+static int mon_fd = -1;
+static const char *mon_fdname;
+
+int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp)
+{
+    g_assert(cur_mon);
+    g_assert(mon == cur_mon);
+    if (mon_fd == -1 || !g_str_equal(mon_fdname, fdname)) {
+        error_setg(errp, "No fd named %s", fdname);
+        return -1;
+    }
+    return dup(mon_fd);
+}
+
+/* Syms in libqemustub.a are discarded at .o file granularity.
+ * To replace monitor_get_fd() we must ensure everything in
+ * stubs/monitor.c is defined, to make sure monitor.o is discarded
+ * otherwise we get duplicate syms at link time.
+ */
+Monitor *cur_mon;
+void monitor_init(Chardev *chr, int flags) {}
+
+
+static void test_socket_fd_pass_good(void)
+{
+    SocketAddress addr;
+    int fd;
+
+    cur_mon = g_malloc(1); /* Fake a monitor */
+    mon_fdname = "myfd";
+    mon_fd = qemu_socket(AF_INET, SOCK_STREAM, 0);
+    g_assert_cmpint(mon_fd, >, STDERR_FILENO);
+
+    addr.type = SOCKET_ADDRESS_TYPE_FD;
+    addr.u.fd.str = g_strdup(mon_fdname);
+
+    fd = socket_connect(&addr, &error_abort);
+    g_assert_cmpint(fd, !=, -1);
+    g_assert_cmpint(fd, !=, mon_fd);
+    close(fd);
+
+    fd = socket_listen(&addr, &error_abort);
+    g_assert_cmpint(fd, !=, -1);
+    g_assert_cmpint(fd, !=, mon_fd);
+    close(fd);
+
+    g_free(addr.u.fd.str);
+    mon_fdname = NULL;
+    close(mon_fd);
+    mon_fd = -1;
+    g_free(cur_mon);
+    cur_mon = NULL;
+}
+
+static void test_socket_fd_pass_bad(void)
+{
+    SocketAddress addr;
+    Error *err = NULL;
+    int fd;
+
+    cur_mon = g_malloc(1); /* Fake a monitor */
+    mon_fdname = "myfd";
+    mon_fd = dup(STDOUT_FILENO);
+    g_assert_cmpint(mon_fd, >, STDERR_FILENO);
+
+    addr.type = SOCKET_ADDRESS_TYPE_FD;
+    addr.u.fd.str = g_strdup(mon_fdname);
+
+    fd = socket_connect(&addr, &err);
+    g_assert_cmpint(fd, ==, -1);
+    error_free_or_abort(&err);
+
+    fd = socket_listen(&addr, &err);
+    g_assert_cmpint(fd, ==, -1);
+    error_free_or_abort(&err);
+
+    g_free(addr.u.fd.str);
+    mon_fdname = NULL;
+    close(mon_fd);
+    mon_fd = -1;
+    g_free(cur_mon);
+    cur_mon = NULL;
+}
+
+int main(int argc, char **argv)
+{
+    bool has_ipv4, has_ipv6;
+
+    module_call_init(MODULE_INIT_QOM);
+    socket_init();
+
+    g_test_init(&argc, &argv, NULL);
+
+    /* We're creating actual IPv4/6 sockets, so we should
+     * check if the host running tests actually supports
+     * each protocol to avoid breaking tests on machines
+     * with either IPv4 or IPv6 disabled.
+     */
+    if (socket_check_protocol_support(&has_ipv4, &has_ipv6) < 0) {
+        return 1;
+    }
+
+    if (has_ipv4) {
+        g_test_add_func("/socket/fd-pass/good",
+                        test_socket_fd_pass_good);
+        g_test_add_func("/socket/fd-pass/bad",
+                        test_socket_fd_pass_bad);
+    }
+
+    return g_test_run();
+}
diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
index 5e42f6d88d..6a7b194428 100644
--- a/util/qemu-sockets.c
+++ b/util/qemu-sockets.c
@@ -1027,6 +1027,20 @@ fail:
     return NULL;
 }
 
+static int socket_get_fd(const char *fdstr, Error **errp)
+{
+    int fd = monitor_get_fd(cur_mon, fdstr, errp);
+    if (fd < 0) {
+        return -1;
+    }
+    if (!fd_is_socket(fd)) {
+        error_setg(errp, "File descriptor '%s' is not a socket", fdstr);
+        close(fd);
+        return -1;
+    }
+    return fd;
+}
+
 int socket_connect(SocketAddress *addr, Error **errp)
 {
     int fd;
@@ -1041,7 +1055,7 @@ int socket_connect(SocketAddress *addr, Error **errp)
         break;
 
     case SOCKET_ADDRESS_TYPE_FD:
-        fd = monitor_get_fd(cur_mon, addr->u.fd.str, errp);
+        fd = socket_get_fd(addr->u.fd.str, errp);
         break;
 
     case SOCKET_ADDRESS_TYPE_VSOCK:
@@ -1068,7 +1082,7 @@ int socket_listen(SocketAddress *addr, Error **errp)
         break;
 
     case SOCKET_ADDRESS_TYPE_FD:
-        fd = monitor_get_fd(cur_mon, addr->u.fd.str, errp);
+        fd = socket_get_fd(addr->u.fd.str, errp);
         break;
 
     case SOCKET_ADDRESS_TYPE_VSOCK:
-- 
2.14.3