From 5bf07e1b3a74232bfb8332275110be1a5da50f83 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Tue, 28 Sep 2021 18:55:49 +0200 Subject: Linux: Simplify __opensock and fix race condition [BZ #28353] AF_NETLINK support is not quite optional on modern Linux systems anymore, so it is likely that the first attempt will always succeed. Consequently, there is no need to cache the result. Keep AF_UNIX and the Internet address families as a fallback, for the rare case that AF_NETLINK is missing. The other address families previously probed are totally obsolete be now, so remove them. Use this simplified version as the generic implementation, disabling Netlink support as needed. --- socket/opensock.c | 65 +++++++++++++++++++------------------------------------ 1 file changed, 22 insertions(+), 43 deletions(-) (limited to 'socket') diff --git a/socket/opensock.c b/socket/opensock.c index 37148d4743..ff94d27a61 100644 --- a/socket/opensock.c +++ b/socket/opensock.c @@ -1,4 +1,5 @@ -/* Copyright (C) 1999-2021 Free Software Foundation, Inc. +/* Create socket with an unspecified address family for use with ioctl. + Copyright (C) 1999-2021 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or @@ -15,56 +16,34 @@ License along with the GNU C Library; if not, see . */ -#include +#include #include -#include /* Return a socket of any type. The socket can be used in subsequent ioctl calls to talk to the kernel. */ int __opensock (void) { - /* Cache the last AF that worked, to avoid many redundant calls to - socket(). */ - static int sock_af = -1; - int fd = -1; - __libc_lock_define_initialized (static, lock); - - if (sock_af != -1) - { - fd = __socket (sock_af, SOCK_DGRAM, 0); - if (fd != -1) - return fd; - } - - __libc_lock_lock (lock); - - if (sock_af != -1) - fd = __socket (sock_af, SOCK_DGRAM, 0); - - if (fd == -1) - { -#ifdef AF_INET - fd = __socket (sock_af = AF_INET, SOCK_DGRAM, 0); -#endif -#ifdef AF_INET6 - if (fd < 0) - fd = __socket (sock_af = AF_INET6, SOCK_DGRAM, 0); -#endif -#ifdef AF_IPX - if (fd < 0) - fd = __socket (sock_af = AF_IPX, SOCK_DGRAM, 0); -#endif -#ifdef AF_AX25 - if (fd < 0) - fd = __socket (sock_af = AF_AX25, SOCK_DGRAM, 0); -#endif -#ifdef AF_APPLETALK - if (fd < 0) - fd = __socket (sock_af = AF_APPLETALK, SOCK_DGRAM, 0); + /* SOCK_DGRAM is supported by all address families. (Netlink does + not support SOCK_STREAM.) */ + int type = SOCK_DGRAM | SOCK_CLOEXEC; + int fd; + +#ifdef AF_NETLINK + fd = __socket (AF_NETLINK, type, 0); + if (fd >= 0) + return fd; #endif - } - __libc_lock_unlock (lock); + fd = __socket (AF_UNIX, type, 0); + if (fd >= 0) + return fd; + fd = __socket (AF_INET, type, 0); + if (fd >= 0) + return fd; + fd = __socket (AF_INET6, type, 0); + if (fd >= 0) + return fd; + __set_errno (ENOENT); return fd; } -- cgit 1.4.1