9e45fb09bf
This also makes sure the control buffer is properly aligned. This matters, as otherwise the control buffer might not be aligned and the cmsg buffer counting might be off. The incorrect alignment is becoming visible by using recvmsg_safe() as we suddenly notice the MSG_CTRUNC bit set because of this. That said, apparently this isn't enough to make this work on all kernels. Since I couldn't figure this out, we now add 1K to the buffer to be sure. We do this once already, also for a pktinfo structure (though an IPv4/IPv6) one. I am puzzled by this, but this shouldn't matter much. it works locally just fine, except for those ubuntu CI kernels... While we are at it, make some other changes too, to simplify and modernize the function.
449 lines
13 KiB
C
449 lines
13 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#include <netinet/in.h>
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#include <stdbool.h>
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#include <unistd.h>
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#include "sd-netlink.h"
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#include "alloc-util.h"
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#include "fd-util.h"
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#include "format-util.h"
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#include "io-util.h"
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#include "netlink-internal.h"
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#include "netlink-types.h"
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#include "netlink-util.h"
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#include "socket-util.h"
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#include "util.h"
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/* For some reason we need some extra cmsg space on some kernels. It's not clear why, and one of those days
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* we need to track this down. See: https://github.com/systemd/systemd/pull/15457 */
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#define EXTRA_CMSG_SPACE 1024
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int socket_open(int family) {
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int fd;
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fd = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, family);
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if (fd < 0)
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return -errno;
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return fd_move_above_stdio(fd);
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}
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static int broadcast_groups_get(sd_netlink *nl) {
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_cleanup_free_ uint32_t *groups = NULL;
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socklen_t len = 0, old_len;
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unsigned i, j;
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int r;
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assert(nl);
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assert(nl->fd >= 0);
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r = getsockopt(nl->fd, SOL_NETLINK, NETLINK_LIST_MEMBERSHIPS, NULL, &len);
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if (r < 0) {
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if (errno == ENOPROTOOPT) {
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nl->broadcast_group_dont_leave = true;
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return 0;
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} else
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return -errno;
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}
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if (len == 0)
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return 0;
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groups = new0(uint32_t, len);
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if (!groups)
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return -ENOMEM;
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old_len = len;
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r = getsockopt(nl->fd, SOL_NETLINK, NETLINK_LIST_MEMBERSHIPS, groups, &len);
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if (r < 0)
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return -errno;
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if (old_len != len)
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return -EIO;
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r = hashmap_ensure_allocated(&nl->broadcast_group_refs, NULL);
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if (r < 0)
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return r;
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for (i = 0; i < len; i++) {
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for (j = 0; j < sizeof(uint32_t) * 8; j++) {
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uint32_t offset;
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unsigned group;
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offset = 1U << j;
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if (!(groups[i] & offset))
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continue;
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group = i * sizeof(uint32_t) * 8 + j + 1;
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r = hashmap_put(nl->broadcast_group_refs, UINT_TO_PTR(group), UINT_TO_PTR(1));
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if (r < 0)
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return r;
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}
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}
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return 0;
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}
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int socket_bind(sd_netlink *nl) {
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socklen_t addrlen;
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int r;
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r = setsockopt_int(nl->fd, SOL_NETLINK, NETLINK_PKTINFO, true);
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if (r < 0)
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return r;
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addrlen = sizeof(nl->sockaddr);
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r = bind(nl->fd, &nl->sockaddr.sa, addrlen);
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/* ignore EINVAL to allow opening an already bound socket */
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if (r < 0 && errno != EINVAL)
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return -errno;
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r = getsockname(nl->fd, &nl->sockaddr.sa, &addrlen);
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if (r < 0)
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return -errno;
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r = broadcast_groups_get(nl);
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if (r < 0)
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return r;
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return 0;
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}
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static unsigned broadcast_group_get_ref(sd_netlink *nl, unsigned group) {
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assert(nl);
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return PTR_TO_UINT(hashmap_get(nl->broadcast_group_refs, UINT_TO_PTR(group)));
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}
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static int broadcast_group_set_ref(sd_netlink *nl, unsigned group, unsigned n_ref) {
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int r;
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assert(nl);
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r = hashmap_replace(nl->broadcast_group_refs, UINT_TO_PTR(group), UINT_TO_PTR(n_ref));
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if (r < 0)
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return r;
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return 0;
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}
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static int broadcast_group_join(sd_netlink *nl, unsigned group) {
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int r;
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assert(nl);
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assert(nl->fd >= 0);
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assert(group > 0);
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r = setsockopt(nl->fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &group, sizeof(group));
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if (r < 0)
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return -errno;
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return 0;
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}
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int socket_broadcast_group_ref(sd_netlink *nl, unsigned group) {
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unsigned n_ref;
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int r;
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assert(nl);
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n_ref = broadcast_group_get_ref(nl, group);
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n_ref++;
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r = hashmap_ensure_allocated(&nl->broadcast_group_refs, NULL);
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if (r < 0)
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return r;
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r = broadcast_group_set_ref(nl, group, n_ref);
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if (r < 0)
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return r;
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if (n_ref > 1)
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/* not yet in the group */
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return 0;
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r = broadcast_group_join(nl, group);
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if (r < 0)
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return r;
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return 0;
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}
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static int broadcast_group_leave(sd_netlink *nl, unsigned group) {
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int r;
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assert(nl);
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assert(nl->fd >= 0);
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assert(group > 0);
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if (nl->broadcast_group_dont_leave)
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return 0;
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r = setsockopt(nl->fd, SOL_NETLINK, NETLINK_DROP_MEMBERSHIP, &group, sizeof(group));
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if (r < 0)
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return -errno;
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return 0;
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}
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int socket_broadcast_group_unref(sd_netlink *nl, unsigned group) {
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unsigned n_ref;
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int r;
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assert(nl);
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n_ref = broadcast_group_get_ref(nl, group);
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assert(n_ref > 0);
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n_ref--;
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r = broadcast_group_set_ref(nl, group, n_ref);
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if (r < 0)
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return r;
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if (n_ref > 0)
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/* still refs left */
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return 0;
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r = broadcast_group_leave(nl, group);
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if (r < 0)
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return r;
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return 0;
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}
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/* returns the number of bytes sent, or a negative error code */
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int socket_write_message(sd_netlink *nl, sd_netlink_message *m) {
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union {
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struct sockaddr sa;
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struct sockaddr_nl nl;
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} addr = {
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.nl.nl_family = AF_NETLINK,
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};
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ssize_t k;
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assert(nl);
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assert(m);
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assert(m->hdr);
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k = sendto(nl->fd, m->hdr, m->hdr->nlmsg_len,
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0, &addr.sa, sizeof(addr));
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if (k < 0)
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return -errno;
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return k;
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}
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static int socket_recv_message(int fd, struct iovec *iov, uint32_t *ret_mcast_group, bool peek) {
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union sockaddr_union sender;
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CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct nl_pktinfo)) + EXTRA_CMSG_SPACE) control;
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struct msghdr msg = {
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.msg_iov = iov,
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.msg_iovlen = 1,
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.msg_name = &sender,
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.msg_namelen = sizeof(sender),
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.msg_control = &control,
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.msg_controllen = sizeof(control),
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};
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ssize_t n;
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assert(fd >= 0);
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assert(iov);
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n = recvmsg_safe(fd, &msg, MSG_TRUNC | (peek ? MSG_PEEK : 0));
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if (n == -ENOBUFS)
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return log_debug_errno(n, "rtnl: kernel receive buffer overrun");
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if (IN_SET(n, -EAGAIN, -EINTR))
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return 0;
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if (n < 0)
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return (int) n;
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if (sender.nl.nl_pid != 0) {
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/* not from the kernel, ignore */
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log_debug("rtnl: ignoring message from portid %"PRIu32, sender.nl.nl_pid);
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if (peek) {
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/* drop the message */
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n = recvmsg_safe(fd, &msg, 0);
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if (n < 0)
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return (int) n;
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}
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return 0;
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}
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if (ret_mcast_group) {
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struct nl_pktinfo *pi;
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pi = CMSG_FIND_DATA(&msg, SOL_NETLINK, NETLINK_PKTINFO, struct nl_pktinfo);
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if (pi)
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*ret_mcast_group = pi->group;
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else
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*ret_mcast_group = 0;
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}
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return (int) n;
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}
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/* On success, the number of bytes received is returned and *ret points to the received message
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* which has a valid header and the correct size.
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* If nothing useful was received 0 is returned.
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* On failure, a negative error code is returned.
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*/
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int socket_read_message(sd_netlink *rtnl) {
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_cleanup_(sd_netlink_message_unrefp) sd_netlink_message *first = NULL;
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struct iovec iov = {};
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uint32_t group = 0;
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bool multi_part = false, done = false;
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struct nlmsghdr *new_msg;
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size_t len;
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int r;
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unsigned i = 0;
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assert(rtnl);
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assert(rtnl->rbuffer);
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assert(rtnl->rbuffer_allocated >= sizeof(struct nlmsghdr));
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/* read nothing, just get the pending message size */
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r = socket_recv_message(rtnl->fd, &iov, NULL, true);
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if (r <= 0)
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return r;
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else
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len = (size_t) r;
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/* make room for the pending message */
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if (!greedy_realloc((void **)&rtnl->rbuffer,
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&rtnl->rbuffer_allocated,
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len, sizeof(uint8_t)))
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return -ENOMEM;
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iov = IOVEC_MAKE(rtnl->rbuffer, rtnl->rbuffer_allocated);
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/* read the pending message */
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r = socket_recv_message(rtnl->fd, &iov, &group, false);
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if (r <= 0)
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return r;
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else
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len = (size_t) r;
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if (len > rtnl->rbuffer_allocated)
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/* message did not fit in read buffer */
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return -EIO;
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if (NLMSG_OK(rtnl->rbuffer, len) && rtnl->rbuffer->nlmsg_flags & NLM_F_MULTI) {
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multi_part = true;
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for (i = 0; i < rtnl->rqueue_partial_size; i++) {
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if (rtnl_message_get_serial(rtnl->rqueue_partial[i]) ==
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rtnl->rbuffer->nlmsg_seq) {
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first = rtnl->rqueue_partial[i];
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break;
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}
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}
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}
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for (new_msg = rtnl->rbuffer; NLMSG_OK(new_msg, len) && !done; new_msg = NLMSG_NEXT(new_msg, len)) {
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_cleanup_(sd_netlink_message_unrefp) sd_netlink_message *m = NULL;
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const NLType *nl_type;
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if (!group && new_msg->nlmsg_pid != rtnl->sockaddr.nl.nl_pid)
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/* not broadcast and not for us */
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continue;
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if (new_msg->nlmsg_type == NLMSG_NOOP)
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/* silently drop noop messages */
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continue;
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if (new_msg->nlmsg_type == NLMSG_DONE) {
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/* finished reading multi-part message */
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done = true;
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/* if first is not defined, put NLMSG_DONE into the receive queue. */
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if (first)
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continue;
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}
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/* check that we support this message type */
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r = type_system_root_get_type(rtnl, &nl_type, new_msg->nlmsg_type);
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if (r < 0) {
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if (r == -EOPNOTSUPP)
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log_debug("sd-netlink: ignored message with unknown type: %i",
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new_msg->nlmsg_type);
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continue;
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}
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/* check that the size matches the message type */
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if (new_msg->nlmsg_len < NLMSG_LENGTH(type_get_size(nl_type))) {
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log_debug("sd-netlink: message is shorter than expected, dropping");
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continue;
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}
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r = message_new_empty(rtnl, &m);
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if (r < 0)
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return r;
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m->broadcast = !!group;
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m->hdr = memdup(new_msg, new_msg->nlmsg_len);
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if (!m->hdr)
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return -ENOMEM;
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/* seal and parse the top-level message */
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r = sd_netlink_message_rewind(m, rtnl);
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if (r < 0)
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return r;
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/* push the message onto the multi-part message stack */
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if (first)
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m->next = first;
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first = TAKE_PTR(m);
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}
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if (len > 0)
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log_debug("sd-netlink: discarding %zu bytes of incoming message", len);
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if (!first)
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return 0;
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if (!multi_part || done) {
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/* we got a complete message, push it on the read queue */
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r = rtnl_rqueue_make_room(rtnl);
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if (r < 0)
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return r;
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rtnl->rqueue[rtnl->rqueue_size++] = TAKE_PTR(first);
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if (multi_part && (i < rtnl->rqueue_partial_size)) {
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/* remove the message form the partial read queue */
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memmove(rtnl->rqueue_partial + i,rtnl->rqueue_partial + i + 1,
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sizeof(sd_netlink_message*) * (rtnl->rqueue_partial_size - i - 1));
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rtnl->rqueue_partial_size--;
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}
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return 1;
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} else {
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/* we only got a partial multi-part message, push it on the
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partial read queue */
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if (i < rtnl->rqueue_partial_size)
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rtnl->rqueue_partial[i] = TAKE_PTR(first);
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else {
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r = rtnl_rqueue_partial_make_room(rtnl);
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if (r < 0)
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return r;
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rtnl->rqueue_partial[rtnl->rqueue_partial_size++] = TAKE_PTR(first);
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}
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return 0;
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}
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}
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