From 3b0d92d7b0df034d0e98be852569a6dec771121e Mon Sep 17 00:00:00 2001 From: Thomas Haller Date: Fri, 6 Mar 2015 12:33:49 +0100 Subject: [PATCH 1/1] lib/socket: detect protocol in nl_socket_set_fd() With support for socket option SO_PROTOCOL we don't need the protocol argument to nl_socket_set_fd(). Maybe we should drop the protocol argument and just not support nl_socket_set_fd() on older systems. But instead keep the argument and allow passing -1 to autodetect it. If the user sets a protocol option, we check via getsockopt() that the value is correct and error out otherwise. On older kernels, the user must set the value. Otherwise nl_socket_set_fd() will fail. Signed-off-by: Thomas Haller (cherry picked from commit 24d333075ab4efa1406d836b821e1484a124dbfc) --- lib/socket.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 63 insertions(+), 9 deletions(-) diff --git a/lib/socket.c b/lib/socket.c index 049b8b9..b29d1da 100644 --- a/lib/socket.c +++ b/lib/socket.c @@ -29,6 +29,8 @@ #include "defs.h" +#include "sys/socket.h" + #include #include #include @@ -577,7 +579,12 @@ int nl_socket_get_fd(const struct nl_sock *sk) * socket similar to nl_connect(). * * @arg sk Netlink socket (required) - * @arg protocol Netlink protocol to use (required) + * @arg protocol The socket protocol (optional). Linux 2.6.32 supports + * the socket option SO_PROTOCOL. In this case, you can set + * protocol to a negative value and let it autodetect. + * If you set it to a non-negative value, the detected protocol + * must match the one provided. + * To support older kernels, you must specify the protocol. * @arg fd Socket file descriptor to use (required) * * Set the socket file descriptor. @fd must be valid and bind'ed. @@ -592,7 +599,7 @@ int nl_socket_get_fd(const struct nl_sock *sk) * possibly unusable. * * @retval -NLE_BAD_SOCK Netlink socket is already connected - * @retval -NLE_INVAL Socket is not connected + * @retval -NLE_INVAL Socket is of unexpected type */ int nl_socket_set_fd(struct nl_sock *sk, int protocol, int fd) { @@ -600,6 +607,7 @@ int nl_socket_set_fd(struct nl_sock *sk, int protocol, int fd) socklen_t addrlen; char buf[64]; struct sockaddr_nl local = { 0 }; + int so_type = -1, so_protocol = -1; if (sk->s_fd != -1) return -NLE_BAD_SOCK; @@ -610,16 +618,62 @@ int nl_socket_set_fd(struct nl_sock *sk, int protocol, int fd) err = getsockname(fd, (struct sockaddr *) &local, &addrlen); if (err < 0) { - NL_DBG(4, "nl_socket_set_fd(%p): getsockname() failed with %d (%s)\n", - sk, errno, strerror_r(errno, buf, sizeof(buf))); + NL_DBG(4, "nl_socket_set_fd(%p,%d): getsockname() failed with %d (%s)\n", + sk, fd, errno, strerror_r(errno, buf, sizeof(buf))); return -nl_syserr2nlerr(errno); } - if (addrlen != sizeof(local)) - return -NLE_NOADDR; + return -NLE_INVAL; + if (local.nl_family != AF_NETLINK) { + NL_DBG(4, "nl_socket_set_fd(%p,%d): getsockname() returned family %d instead of %d (AF_NETLINK)\n", + sk, fd, local.nl_family, AF_NETLINK); + return -NLE_INVAL; + } + + addrlen = sizeof(so_type); + err = getsockopt(fd, SOL_SOCKET, SO_TYPE, &so_type, &addrlen); + if (err < 0) { + NL_DBG(4, "nl_socket_set_fd(%p,%d): getsockopt() for SO_TYPE failed with %d (%s)\n", + sk, fd, errno, strerror_r(errno, buf, sizeof(buf))); + return -nl_syserr2nlerr(errno); + } + if (addrlen != sizeof(so_type)) + return -NLE_INVAL; + if (so_type != SOCK_RAW) { + NL_DBG(4, "nl_socket_set_fd(%p,%d): getsockopt() returned SO_TYPE %d instead of %d (SOCK_RAW)\n", + sk, fd, so_type, SOCK_RAW); + return -NLE_INVAL; + } - if (local.nl_family != AF_NETLINK) - return -NLE_AF_NOSUPPORT; +#if SO_PROTOCOL + addrlen = sizeof(so_protocol); + err = getsockopt(fd, SOL_SOCKET, SO_PROTOCOL, &so_protocol, &addrlen); + if (err < 0) { + if (errno == ENOPROTOOPT) + goto no_so_protocol; + NL_DBG(4, "nl_socket_set_fd(%p,%d): getsockopt() for SO_PROTOCOL failed with %d (%s)\n", + sk, fd, errno, strerror_r(errno, buf, sizeof(buf))); + return -nl_syserr2nlerr(errno); + } + if (addrlen != sizeof(so_protocol)) + return -NLE_INVAL; + if (protocol >= 0 && protocol != so_protocol) { + NL_DBG(4, "nl_socket_set_fd(%p,%d): getsockopt() for SO_PROTOCOL returned %d instead of %d\n", + sk, fd, so_protocol, protocol); + return -NLE_INVAL; + } + + if (0) +#endif + { +no_so_protocol: + if (protocol < 0) { + NL_DBG(4, "nl_socket_set_fd(%p,%d): unknown protocol and unable to detect it via SO_PROTOCOL socket option\n", + sk, fd); + return -NLE_INVAL; + } + so_protocol = protocol; + } if (sk->s_local.nl_pid != local.nl_pid) { /* the port id differs. The socket is using a port id not managed by @@ -629,7 +683,7 @@ int nl_socket_set_fd(struct nl_sock *sk, int protocol, int fd) } sk->s_local = local; sk->s_fd = fd; - sk->s_proto = protocol; + sk->s_proto = so_protocol; return 0; } -- 1.9.3