Use FD_CLOEXEC on ListenSockets

It's good hygiene if e.g. an extension launches a subprogram when
being loaded. We went through some effort to close them in the child
process in EXEC_BACKEND mode, but it's better to not hand them down to
the child process in the first place. We still need to close them
after fork when !EXEC_BACKEND, but it's a little simpler.

In the passing, LOG a message if closing the client connection or
listen socket fails. Shouldn't happen, but if it does, would be nice
to know.

Reviewed-by: Tristan Partin, Andres Freund, Thomas Munro
Discussion: https://www.postgresql.org/message-id/7a59b073-5b5b-151e-7ed3-8b01ff7ce9ef@iki.fi

diff --git a/src/backend/libpq/pqcomm.c b/src/backend/libpq/pqcomm.c
index 1bdcbe4f6363f6df75485e89313aeb50fefa70ee..8d217b06455d405094bb28310dc0fd45b5153503 100644 (file)
--- a/src/backend/libpq/pqcomm.c
+++ b/src/backend/libpq/pqcomm.c
@@ -458,6 +458,9 @@ StreamServerPort(int family, const char *hostName, unsigned short portNumber,
        }
 
 #ifndef WIN32
+       /* Don't give the listen socket to any subprograms we execute. */
+       if (fcntl(fd, F_SETFD, FD_CLOEXEC) < 0)
+           elog(FATAL, "fcntl(F_SETFD) failed on socket: %m");
 
        /*
         * Without the SO_REUSEADDR flag, a new postmaster can't be started
@@ -831,7 +834,8 @@ StreamConnection(pgsocket server_fd, Port *port)
 void
 StreamClose(pgsocket sock)
 {
-   closesocket(sock);
+   if (closesocket(sock) != 0)
+       elog(LOG, "could not close client or listen socket: %m");
 }
 
 /*

diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 07d376d77ec2ed976ac7cb8770b483557a948dc6..41bccb46a877c6c7845fb206a2b853c10fdff1dd 100644 (file)
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -496,7 +496,6 @@ typedef struct
    Port        port;
    InheritableSocket portsocket;
    char        DataDir[MAXPGPATH];
-   pgsocket    ListenSocket[MAXLISTEN];
    int32       MyCancelKey;
    int         MyPMChildSlot;
 #ifndef WIN32
@@ -2545,8 +2544,6 @@ ConnFree(Port *port)
 void
 ClosePostmasterPorts(bool am_syslogger)
 {
-   int         i;
-
    /* Release resources held by the postmaster's WaitEventSet. */
    if (pm_wait_set)
    {
@@ -2573,8 +2570,12 @@ ClosePostmasterPorts(bool am_syslogger)
    /*
     * Close the postmaster's listen sockets.  These aren't tracked by fd.c,
     * so we don't call ReleaseExternalFD() here.
+    *
+    * The listen sockets are marked as FD_CLOEXEC, so this isn't needed in
+    * EXEC_BACKEND mode.
     */
-   for (i = 0; i < MAXLISTEN; i++)
+#ifndef EXEC_BACKEND
+   for (int i = 0; i < MAXLISTEN; i++)
    {
        if (ListenSocket[i] != PGINVALID_SOCKET)
        {
@@ -2582,6 +2583,7 @@ ClosePostmasterPorts(bool am_syslogger)
            ListenSocket[i] = PGINVALID_SOCKET;
        }
    }
+#endif
 
    /*
     * If using syslogger, close the read side of the pipe.  We don't bother
@@ -6038,8 +6040,6 @@ save_backend_variables(BackendParameters *param, Port *port,
 
    strlcpy(param->DataDir, DataDir, MAXPGPATH);
 
-   memcpy(&param->ListenSocket, &ListenSocket, sizeof(ListenSocket));
-
    param->MyCancelKey = MyCancelKey;
    param->MyPMChildSlot = MyPMChildSlot;
 
@@ -6271,8 +6271,6 @@ restore_backend_variables(BackendParameters *param, Port *port)
 
    SetDataDir(param->DataDir);
 
-   memcpy(&ListenSocket, &param->ListenSocket, sizeof(ListenSocket));
-
    MyCancelKey = param->MyCancelKey;
    MyPMChildSlot = param->MyPMChildSlot;