diff options
Diffstat (limited to 'src/monitor/monitor_netlink.c')
| -rw-r--r-- | src/monitor/monitor_netlink.c | 406 |
1 files changed, 406 insertions, 0 deletions
diff --git a/src/monitor/monitor_netlink.c b/src/monitor/monitor_netlink.c new file mode 100644 index 00000000..da4b673d --- /dev/null +++ b/src/monitor/monitor_netlink.c @@ -0,0 +1,406 @@ +/* + SSSD - Service monitor - netlink support + + Authors: + Jakub Hrozek <jhrozek@redhat.com> + Parts of this code were borrowed from NetworkManager + + Copyright (C) 2010 Red Hat + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. +*/ + +#include <talloc.h> +#include <tevent.h> +#include <sys/types.h> +#define __USE_GNU /* needed for struct ucred */ +#include <sys/socket.h> +#include <unistd.h> +#include <fcntl.h> + +#include "monitor/monitor.h" +#include "util/util.h" + +#ifdef HAVE_LIBNL +#include <linux/if.h> +#include <linux/socket.h> +#include <linux/rtnetlink.h> +#include <netlink/netlink.h> +#include <netlink/utils.h> +#include <netlink/route/addr.h> +#include <netlink/route/link.h> +#include <netlink/route/rtnl.h> +#include <netlink/handlers.h> +#endif + +/* Linux header file confusion causes this to be undefined. */ +#ifndef SOL_NETLINK +#define SOL_NETLINK 270 +#endif + +#ifdef HAVE_LIBNL_OLDER_THAN_1_1 +#define nlw_get_fd nl_handle_get_fd +#define nlw_recvmsgs_default nl_recvmsgs_def +#define nlw_get_pid nl_handle_get_pid +#define nlw_object_match nl_object_match +#define NLW_OK NL_PROCEED +#define OBJ_CAST(ptr) ((struct nl_object *) (ptr)) +#else +#define nlw_get_fd nl_socket_get_fd +#define nlw_recvmsgs_default nl_recvmsgs_default +#define nlw_get_pid nl_socket_get_local_port +#define nlw_object_match nl_object_match_filter +#define NLW_OK NL_OK +#endif + +struct netlink_ctx { +#ifdef HAVE_LIBNL + struct nl_handle *nlh; +#endif + struct tevent_fd *tefd; + + network_change_cb change_cb; + void *cb_data; +}; + +#ifdef HAVE_LIBNL +static int netlink_ctx_destructor(void *ptr) +{ + struct netlink_ctx *nlctx; + nlctx = talloc_get_type(ptr, struct netlink_ctx); + + nl_handle_destroy(nlctx->nlh); + return 0; +} + +/******************************************************************* + * Wrappers for different capabilities of different libnl versions + *******************************************************************/ + +static bool nlw_accept_message(struct nl_handle *nlh, + const struct sockaddr_nl *snl, + struct nlmsghdr *hdr) +{ + bool accept_msg = false; + uint32_t local_port; + + if (snl == NULL) { + DEBUG(3, ("Malformed message, skipping\n")); + return false; + } + + /* Accept any messages from the kernel */ + if (hdr->nlmsg_pid == 0 || snl->nl_pid == 0) { + accept_msg = true; + } + + /* And any multicast message directed to our netlink PID, since multicast + * currently requires CAP_ADMIN to use. + */ + local_port = nlw_get_pid(nlh); + if ((hdr->nlmsg_pid == local_port) && snl->nl_groups) { + accept_msg = true; + } + + if (accept_msg == false) { + DEBUG(9, ("ignoring netlink message from PID %d", + hdr->nlmsg_pid)); + } + + return accept_msg; +} + +static bool nlw_is_link_object(struct nl_object *obj) +{ + bool is_link_object = true; + struct rtnl_link *filter; + + filter = rtnl_link_alloc(); + if (!filter) { + DEBUG(0, ("Allocation error!\n")); + is_link_object = false; + } + + /* Ensure it's a link object */ + if (!nlw_object_match(obj, OBJ_CAST(filter))) { + DEBUG(2, ("Not a link object\n")); + is_link_object = false; + } + + rtnl_link_put(filter); + return is_link_object; +} + +static int nlw_enable_passcred(struct nl_handle *nlh) +{ +#ifndef HAVE_NL_SET_PASSCRED + return EOK; /* not available in this version */ +#else + return nl_set_passcred(nlh, 1); /* 1 = enabled */ +#endif +} + +static int nlw_group_subscribe(struct nl_handle *nlh) +{ + int ret; + +#ifdef HAVE_NL_SOCKET_ADD_MEMBERSHIP + ret = nl_socket_add_membership(nlh, RTNLGRP_LINK); + if (ret != 0) { + DEBUG(1, ("Unable to add membership: %s\n", nl_geterror())); + return ret; + } +#else + int nlfd = nlw_get_fd(nlh); + int group = RTNLGRP_LINK; + + errno = 0; + ret = setsockopt(nlfd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, + &group, sizeof(group)); + if (ret < 0) { + ret = errno; + DEBUG(1, ("setsockopt failed (%d): %s\n", ret, strerror(ret))); + return ret; + } +#endif + + return 0; +} + +/******************************************************************* + * Callbacks for validating and receiving messages + *******************************************************************/ + +#ifdef HAVE_LIBNL_OLDER_THAN_1_1 +static int event_msg_recv(struct sockaddr_nl *nla, struct nlmsghdr *hdr, + void *arg) +{ + struct netlink_ctx *ctx = (struct netlink_ctx *) arg; + + if (!nlw_accept_message(ctx->nlh, nla, hdr)) { + return NL_SKIP; + } + + return NLW_OK; +} +#else +static int event_msg_recv(struct nl_msg *msg, void *arg) +{ + struct netlink_ctx *ctx = (struct netlink_ctx *) arg; + struct nlmsghdr *hdr; + const struct sockaddr_nl *snl; + struct ucred *creds; + + creds = nlmsg_get_creds(msg); + if (!creds || creds->uid != 0) { + DEBUG(9, ("Ignoring netlink message from UID %d", + creds ? creds->uid : -1)); + return NL_SKIP; + } + + hdr = nlmsg_hdr(msg); + snl = nlmsg_get_src(msg); + + if (!nlw_accept_message(ctx->nlh, snl, hdr)) { + return NL_SKIP; + } + + return NLW_OK; +} +#endif + +static void link_msg_handler(struct nl_object *obj, void *arg); + +#ifdef HAVE_LIBNL_OLDER_THAN_1_1 +static int event_msg_ready(struct sockaddr_nl *nla, struct nlmsghdr *hdr, + void *arg) +{ + nl_msg_parse(hdr, &link_msg_handler, arg); + return NLW_OK; +} +#else +static int event_msg_ready(struct nl_msg *msg, void *arg) +{ + nl_msg_parse(msg, &link_msg_handler, arg); + return NLW_OK; +} +#endif + +static int nlw_set_callbacks(struct nl_handle *nlh, void *data) +{ + int ret = EIO; + +#ifndef HAVE_NL_SOCKET_MODIFY_CB + struct nl_cb *cb = nl_handle_get_cb(nlh); + ret = nl_cb_set(cb, NL_CB_MSG_IN, NL_CB_CUSTOM, event_msg_recv, data); +#else + ret = nl_socket_modify_cb(nlh, NL_CB_MSG_IN, NL_CB_CUSTOM, event_msg_recv, data); +#endif + if (ret != 0) { + DEBUG(1, ("Unable to set validation callback\n")); + return ret; + } + +#ifndef HAVE_NL_SOCKET_MODIFY_CB + ret = nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, event_msg_ready, data); +#else + ret = nl_socket_modify_cb(nlh, NL_CB_VALID, NL_CB_CUSTOM, event_msg_ready, data); +#endif + if (ret != 0) { + DEBUG(1, ("Unable to set receive callback\n")); + return ret; + } + + return ret; +} + +static void link_msg_handler(struct nl_object *obj, void *arg) +{ + struct netlink_ctx *ctx = (struct netlink_ctx *) arg; + struct rtnl_link *link_obj; + int flags; + int ifidx; + + if (!nlw_is_link_object(obj)) return; + + link_obj = (struct rtnl_link *) obj; + flags = rtnl_link_get_flags(link_obj); + ifidx = rtnl_link_get_ifindex(link_obj); + + DEBUG(8, ("netlink link message: iface idx %d flags 0x%X\n", ifidx, flags)); + + /* IFF_LOWER_UP is the indicator of carrier status */ + if (flags & IFF_LOWER_UP) { + ctx->change_cb(NL_ROUTE_UP, ctx->cb_data); + } else { + ctx->change_cb(NL_ROUTE_DOWN, ctx->cb_data); + } +} + +static void netlink_fd_handler(struct tevent_context *ev, struct tevent_fd *fde, + uint16_t flags, void *data) +{ + struct netlink_ctx *nlctx = talloc_get_type(data, struct netlink_ctx); + int ret; + + if (!nlctx || !nlctx->nlh) { + DEBUG(1, ("Invalid netlink handle, this is most likely a bug!\n")); + return; + } + + ret = nlw_recvmsgs_default(nlctx->nlh); + if (ret != EOK) { + DEBUG(1, ("Error while reading from netlink fd\n")); + return; + } +} + +/******************************************************************* + * Set up the netlink library + *******************************************************************/ + +int setup_netlink(TALLOC_CTX *mem_ctx, struct tevent_context *ev, + network_change_cb change_cb, void *cb_data, + struct netlink_ctx **_nlctx) +{ + struct netlink_ctx *nlctx; + int ret; + int nlfd; + unsigned flags; + + nlctx = talloc_zero(mem_ctx, struct netlink_ctx); + if (!nlctx) return ENOMEM; + talloc_set_destructor((TALLOC_CTX *) nlctx, netlink_ctx_destructor); + + nlctx->change_cb = change_cb; + nlctx->cb_data = cb_data; + + /* allocate the libnl handle and register the default filter set */ + nlctx->nlh = nl_handle_alloc(); + if (!nlctx->nlh) { + DEBUG(1, (("unable to allocate netlink handle: %s"), + nl_geterror())); + ret = ENOMEM; + goto fail; + } + + /* Register our custom message validation filter */ + ret = nlw_set_callbacks(nlctx->nlh, nlctx); + if (ret != 0) { + DEBUG(1, ("Unable to set callbacks\n")); + ret = EIO; + goto fail; + } + + /* Try to start talking to netlink */ + ret = nl_connect(nlctx->nlh, NETLINK_ROUTE); + if (ret != 0) { + DEBUG(1, ("Unable to connect to netlink: %s\n", nl_geterror())); + ret = EIO; + goto fail; + } + + ret = nlw_enable_passcred(nlctx->nlh); + if (ret != 0) { + DEBUG(1, ("Cannot enable credential passing: %s\n", nl_geterror())); + ret = EIO; + goto fail; + } + + /* Subscribe to the LINK group for internal carrier signals */ + ret = nlw_group_subscribe(nlctx->nlh); + if (ret != 0) { + DEBUG(1, ("Unable to subscribe to netlink monitor\n")); + ret = EIO; + goto fail; + } + + nl_disable_sequence_check(nlctx->nlh); + + nlfd = nlw_get_fd(nlctx->nlh); + flags = fcntl(nlfd, F_GETFL, 0); + + errno = 0; + ret = fcntl(nlfd, F_SETFL, flags | O_NONBLOCK); + if (ret < 0) { + ret = errno; + DEBUG(1, ("Cannot set the netlink fd to nonblocking\n")); + goto fail; + } + + nlctx->tefd = tevent_add_fd(ev, nlctx, nlfd, TEVENT_FD_READ, + netlink_fd_handler, nlctx); + if (nlctx->tefd == NULL) { + DEBUG(1, ("tevent_add_fd() failed\n")); + ret = EIO; + goto fail; + } + + *_nlctx = nlctx; + return EOK; + +fail: + talloc_free(nlctx); + return ret; +} + +#else /* HAVE_LIBNL not defined */ +int setup_netlink(TALLOC_CTX *mem_ctx, struct tevent_context *ev, + network_change_cb change_cb, void *cb_data, + struct netlink_ctx **_nlctx) +{ + if (nlctx) *nlctx = NULL; + return EOK; +} +#endif |