From 322da0f2742236197ddc08fc29a68ce9f5fdee0f Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Thu, 6 Oct 2016 15:48:15 +0200 Subject: [PATCH] sd-device/networkd: unify code to get a socket for issuing netdev ioctls on As suggested here: https://github.com/elogind/elogind/pull/4296#issuecomment-251911349 Let's try AF_INET first as socket, but let's fall back to AF_NETLINK, so that we can use a protocol-independent socket here if possible. This has the benefit that our code will still work even if AF_INET/AF_INET6 is made unavailable (for exmple via seccomp), at least on current kernels. --- src/basic/socket-util.c | 17 +++++++++++++++++ src/basic/socket-util.h | 2 ++ 2 files changed, 19 insertions(+) diff --git a/src/basic/socket-util.c b/src/basic/socket-util.c index d8006e66e..a983c67a8 100644 --- a/src/basic/socket-util.c +++ b/src/basic/socket-util.c @@ -1066,3 +1066,20 @@ struct cmsghdr* cmsg_find(struct msghdr *mh, int level, int type, socklen_t leng return NULL; } + +int socket_ioctl_fd(void) { + int fd; + + /* Create a socket to invoke the various network interface ioctl()s on. Traditionally only AF_INET was good for + * that. Since kernel 4.6 AF_NETLINK works for this too. We first try to use AF_INET hence, but if that's not + * available (for example, because it is made unavailable via SECCOMP or such), we'll fall back to the more + * generic AF_NETLINK. */ + + fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC, 0); + if (fd < 0) + fd = socket(AF_NETLINK, SOCK_RAW|SOCK_CLOEXEC, NETLINK_GENERIC); + if (fd < 0) + return -errno; + + return fd; +} diff --git a/src/basic/socket-util.h b/src/basic/socket-util.h index a88ab9fd2..93454f6ac 100644 --- a/src/basic/socket-util.h +++ b/src/basic/socket-util.h @@ -162,3 +162,5 @@ struct cmsghdr* cmsg_find(struct msghdr *mh, int level, int type, socklen_t leng 1 + strnlen(_sa->sun_path+1, sizeof(_sa->sun_path)-1) : \ strnlen(_sa->sun_path, sizeof(_sa->sun_path))); \ }) + +int socket_ioctl_fd(void); -- 2.30.2