sys-socket: Add spice_socketpair helper that makes sockets FD_CLOEXEC

Non-CLOEXEC descriptors leak on QEMU cpr-exec migration.
QEMU has all of its internal sockets CLOEXEC'd,
and expects the external libraries to do the same.

Signed-off-by: Polina Vishneva <polina.vishneva@virtuozzo.com>
Acked-by: Frediano Ziglio <freddy77@gmail.com>

AUTHORS

@@ -98,5 +98,6 @@ Patches also contributed by
     Daniel Kahn Gillmor <dkg@fifthhorseman.net>
     Nicholas Vinson <nvinson234@gmail.com>
     yanlonglong <yanlonglong@kylinos.cn>
+    Polina Vishneva <polina.vishneva@virtuozzo.com>
 
    ....send patches to get your name here...

server/dispatcher.cpp

@@ -85,7 +85,7 @@ Dispatcher::Dispatcher(uint32_t max_message_type):
 {
     int channels[2];
 
-    if (socketpair(AF_LOCAL, SOCK_STREAM, 0, channels) == -1) {
+    if (socket_newpair(SOCK_STREAM, 0, channels) == -1) {
         spice_error("socketpair failed %s", strerror(errno));
         return;
     }

server/sys-socket.c

@@ -34,7 +34,40 @@
 
 #include "sys-socket.h"
 
-#ifdef _WIN32
+#ifndef _WIN32
+int socket_newpair(int type, int protocol, int sv[2])
+{
+    const int domain = AF_LOCAL;
+    int ret;
+    int flags;
+
+#ifdef SOCK_CLOEXEC
+    ret = socketpair(domain, type | SOCK_CLOEXEC, protocol, sv);
+    if (!(ret == -1 && errno == EINVAL)) {
+        /* Failure isn't caused by the lack of SOCK_CLOEXEC support
+         * in the currently running kernel */
+        return ret;
+    }
+#endif
+
+    ret = socketpair(domain, type, protocol, sv);
+    if (ret == -1) {
+        return ret;
+    }
+
+    flags = fcntl(sv[0], F_GETFD);
+    if (flags != -1) {
+        fcntl(sv[0], F_SETFD, flags | FD_CLOEXEC);
+    }
+
+    flags = fcntl(sv[1], F_GETFD);
+    if (flags != -1) {
+        fcntl(sv[1], F_SETFD, flags | FD_CLOEXEC);
+    }
+
+    return ret;
+}
+#else
 // Map Windows socket errors to standard C ones
 // See https://msdn.microsoft.com/en-us/library/windows/desktop/ms740668(v=vs.85).aspx
 void socket_win32_set_errno(void)
@@ -208,6 +241,11 @@ SPICE_CONSTRUCTOR_FUNC(socket_win32_init)
     WSAStartup(MAKEWORD(2, 2), &wsaData);
 }
 
+static inline SOCKET socket_inet_noinherit(int type)
+{
+    return WSASocketW(AF_INET, type, 0, NULL, 0, WSA_FLAG_NO_HANDLE_INHERIT);
+}
+
 int socket_newpair(int type, int protocol, int sv[2])
 {
     struct sockaddr_in sa, sa2;
@@ -219,14 +257,14 @@ int socket_newpair(int type, int protocol, int sv[2])
     }
 
     /* create a listener */
-    s = socket(AF_INET, type, 0);
+    s = socket_inet_noinherit(type);
     if (s == INVALID_SOCKET) {
         return -1;
     }
 
     pairs[1] = INVALID_SOCKET;
 
-    pairs[0] = socket(AF_INET, type, 0);
+    pairs[0] = socket_inet_noinherit(type);
     if (pairs[0] == INVALID_SOCKET) {
         goto cleanup;
     }

server/sys-socket.h

@@ -21,6 +21,10 @@
 #ifndef RED_SYS_SOCKET_H_
 #define RED_SYS_SOCKET_H_
 
+#include <spice/macros.h>
+
+SPICE_BEGIN_DECLS
+
 #ifndef _WIN32
 #  include <sys/socket.h>
 
@@ -32,9 +36,6 @@
 #else
 #  include <winsock2.h>
 #  include <windows.h>
-#  include <spice/macros.h>
-
-SPICE_BEGIN_DECLS
 
 typedef int socklen_t;
 
@@ -139,15 +140,15 @@ socket_accept(int sock, struct sockaddr *addr, int *addrlen)
 #undef accept
 #define accept socket_accept
 
-int socket_newpair(int type, int protocol, int sv[2]);
-#define socketpair(family, type, protocol, sv) socket_newpair(type, protocol, sv)
-
-SPICE_END_DECLS
-
 #endif
 
 #if defined(SO_NOSIGPIPE) && defined(__APPLE__)
 #define MSG_NOSIGNAL 0
 #endif
 
+// Ensures FD_CLOEXEC flag is set if available, in the best way available
+int socket_newpair(int type, int protocol, int sv[2]);
+
+SPICE_END_DECLS
+
 #endif // RED_SYS_SOCKET_H_

server/tests/test-channel.cpp

@@ -183,7 +183,7 @@ static void timeout_watch_count(void *opaque)
 static RedStream *create_dummy_stream(SpiceServer *server, int *p_socket)
 {
     int sv[2];
-    g_assert_cmpint(socketpair(AF_LOCAL, SOCK_STREAM, 0, sv), ==, 0);
+    g_assert_cmpint(socket_newpair(SOCK_STREAM, 0, sv), ==, 0);
     if (p_socket) {
         *p_socket = sv[1];
     }

server/tests/test-leaks.c

@@ -77,7 +77,7 @@ static void server_leaks(void)
 #endif
     g_test_expect_message(G_LOG_DOMAIN, G_LOG_LEVEL_WARNING,
                           "*SSL_accept failed*");
-    g_assert_cmpint(socketpair(AF_LOCAL, SOCK_STREAM, 0, sv), ==, 0);
+    g_assert_cmpint(socket_newpair(SOCK_STREAM, 0, sv), ==, 0);
     socket_close(sv[1]);
     result = spice_server_add_ssl_client(server, sv[0], 1);
     g_assert_cmpint(result, ==, -1);

server/tests/test-sasl.c

@@ -32,6 +32,7 @@
 
 #include "test-glib-compat.h"
 #include "basic-event-loop.h"
+#include "sys-socket.h"
 
 #include <spice/start-packed.h>
 typedef struct SPICE_ATTR_PACKED SpiceInitialMessage {
@@ -602,7 +603,7 @@ setup_thread(void)
            test_num, len, data->mechname, len, data->line);
 
     int sv[2];
-    g_assert_cmpint(socketpair(AF_LOCAL, SOCK_STREAM, 0, sv), ==, 0);
+    g_assert_cmpint(socket_newpair(SOCK_STREAM, 0, sv), ==, 0);
 
     g_assert(spice_server_add_client(server, sv[0], 0) == 0);
 

server/tests/test-smartcard.cpp

@@ -82,7 +82,7 @@ static void test_smartcard_teardown(TestFixture *fixture, gconstpointer user_dat
 static RedStream *create_dummy_stream(SpiceServer *server, int *p_socket)
 {
     int sv[2];
-    g_assert_cmpint(socketpair(AF_LOCAL, SOCK_STREAM, 0, sv), ==, 0);
+    g_assert_cmpint(socket_newpair(SOCK_STREAM, 0, sv), ==, 0);
     if (p_socket) {
         *p_socket = sv[1];
     }

server/tests/test-stream.c

@@ -106,7 +106,7 @@ int main(int argc, char *argv[])
 
     spice_return_val_if_fail(server_init() == 0, -1);
 
-    if (socketpair(AF_LOCAL, SOCK_STREAM, 0, sv) == -1) {
+    if (socket_newpair(SOCK_STREAM, 0, sv) == -1) {
         spice_error("socketpair failed %s", strerror(errno));
         return -1;
     }