/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2013 Tom Gundersen <teg@jklm.no>
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <netinet/in.h>
#include <netinet/ether.h>
#include <stdbool.h>
#include <unistd.h>
#include "util.h"
#include "refcnt.h"
#include "sd-rtnl.h"
#include "rtnl-internal.h"
struct sd_rtnl_message {
RefCount n_ref;
struct nlmsghdr *hdr;
struct rtattr *next_rta;
size_t remaining_size;
bool sealed:1;
};
static int message_new(sd_rtnl_message **ret, size_t initial_size) {
sd_rtnl_message *m;
assert_return(ret, -EINVAL);
assert_return(initial_size >= sizeof(struct nlmsghdr), -EINVAL);
m = new0(sd_rtnl_message, 1);
if (!m)
return -ENOMEM;
m->hdr = malloc0(initial_size);
if (!m->hdr) {
free(m);
return -ENOMEM;
}
m->n_ref = REFCNT_INIT;
m->hdr->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
m->sealed = false;
*ret = m;
return 0;
}
int sd_rtnl_message_route_new(uint16_t nlmsg_type, unsigned char rtm_family,
unsigned char rtm_dst_len, unsigned char rtm_src_len,
unsigned char rtm_tos, unsigned char rtm_table,
unsigned char rtm_scope, unsigned char rtm_protocol,
unsigned char rtm_type, unsigned rtm_flags, sd_rtnl_message **ret) {
struct rtmsg *rtm;
int r;
assert_return(nlmsg_type == RTM_NEWROUTE || nlmsg_type == RTM_DELROUTE ||
nlmsg_type == RTM_GETROUTE, -EINVAL);
assert_return(ret, -EINVAL);
r = message_new(ret, NLMSG_SPACE(sizeof(struct rtmsg)));
if (r < 0)
return r;
(*ret)->hdr->nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
(*ret)->hdr->nlmsg_type = nlmsg_type;
if (nlmsg_type == RTM_NEWROUTE)
(*ret)->hdr->nlmsg_flags |= NLM_F_CREATE | NLM_F_EXCL;
rtm = NLMSG_DATA((*ret)->hdr);
rtm->rtm_family = rtm_family;
rtm->rtm_dst_len = rtm_dst_len;
rtm->rtm_src_len = rtm_src_len;
rtm->rtm_tos = rtm_tos;
rtm->rtm_table = rtm_table;
rtm->rtm_protocol = rtm_protocol;
rtm->rtm_scope = rtm_scope;
rtm->rtm_type = rtm_type;
rtm->rtm_flags = rtm_flags;
return 0;
}
int sd_rtnl_message_link_new(uint16_t nlmsg_type, int index, unsigned int type, unsigned int flags, sd_rtnl_message **ret) {
struct ifinfomsg *ifi;
int r;
assert_return(nlmsg_type == RTM_NEWLINK || nlmsg_type == RTM_DELLINK || nlmsg_type == RTM_GETLINK, -EINVAL);
assert_return(index > 0, -EINVAL);
assert_return(ret, -EINVAL);
r = message_new(ret, NLMSG_SPACE(sizeof(struct ifinfomsg)));
if (r < 0)
return r;
(*ret)->hdr->nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
(*ret)->hdr->nlmsg_type = nlmsg_type;
ifi = NLMSG_DATA((*ret)->hdr);
ifi->ifi_family = AF_UNSPEC;
ifi->ifi_index = index;
ifi->ifi_type = type;
ifi->ifi_flags = flags;
ifi->ifi_change = 0xffffffff;
return 0;
}
int sd_rtnl_message_addr_new(uint16_t nlmsg_type, int index, unsigned char family, unsigned char prefixlen, unsigned char flags, unsigned char scope, sd_rtnl_message **ret) {
struct ifaddrmsg *ifa;
int r;
assert_return(nlmsg_type == RTM_NEWADDR || nlmsg_type == RTM_DELADDR || nlmsg_type == RTM_GETADDR, -EINVAL);
assert_return(index > 0, -EINVAL);
assert_return(ret, -EINVAL);
r = message_new(ret, NLMSG_SPACE(sizeof(struct ifaddrmsg)));
if (r < 0)
return r;
(*ret)->hdr->nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg));
(*ret)->hdr->nlmsg_type = nlmsg_type;
ifa = NLMSG_DATA((*ret)->hdr);
ifa->ifa_family = family;
ifa->ifa_prefixlen = prefixlen;
ifa->ifa_flags = flags;
ifa->ifa_scope = scope;
ifa->ifa_index = index;
return 0;
}
sd_rtnl_message *sd_rtnl_message_ref(sd_rtnl_message *m) {
if (m)
assert_se(REFCNT_INC(m->n_ref) >= 2);
return m;
}
sd_rtnl_message *sd_rtnl_message_unref(sd_rtnl_message *m) {
if (m && REFCNT_DEC(m->n_ref) <= 0) {
free(m->hdr);
free(m);
}
return NULL;
}
int sd_rtnl_message_get_type(sd_rtnl_message *m, uint16_t *type) {
assert_return(m, -EINVAL);
assert_return(type, -EINVAL);
*type = m->hdr->nlmsg_type;
return 0;
}
/* If successful the updated message will be correctly aligned, if unsuccessful the old message is
untouched */
static int add_rtattr(sd_rtnl_message *m, unsigned short type, const void *data, size_t data_length) {
uint32_t rta_length, message_length;
struct nlmsghdr *new_hdr;
struct rtattr *rta;
assert_return(m, -EINVAL);
assert_return(m->hdr, -EINVAL);
assert_return(NLMSG_ALIGN(m->hdr->nlmsg_len) == m->hdr->nlmsg_len, -EINVAL);
assert_return(data, -EINVAL);
assert_return(data_length > 0, -EINVAL);
/* get the size of the new rta attribute (without padding at the end) */
rta_length = RTA_LENGTH(data_length);
/* get the new message size (with padding between the old message and the new attrib,
* but no padding after)
*/
message_length = m->hdr->nlmsg_len + RTA_ALIGN(rta_length);
/* realloc to fit the new attribute */
new_hdr = realloc(m->hdr, message_length);
if (!new_hdr)
return -ENOMEM;
m->hdr = new_hdr;
/* get pointer to the attribute we are about to add */
rta = (struct rtattr *) ((uint8_t *) m->hdr + m->hdr->nlmsg_len);
/* update message size */
m->hdr->nlmsg_len = message_length;
/* fill in the attribute */
rta->rta_type = type;
rta->rta_len = rta_length;
/* we don't deal with the case where the user lies about the type and gives us
* too little data (so don't do that)
*/
memcpy(RTA_DATA(rta), data, data_length);
return 0;
}
int sd_rtnl_message_append(sd_rtnl_message *m, unsigned short type, const void *data) {
uint16_t rtm_type;
struct ifaddrmsg *ifa;
struct rtmsg *rtm;
assert_return(m, -EINVAL);
assert_return(data, -EINVAL);
sd_rtnl_message_get_type(m, &rtm_type);
switch (rtm_type) {
case RTM_NEWLINK:
case RTM_DELLINK:
case RTM_GETLINK:
switch (type) {
case IFLA_IFNAME:
case IFLA_QDISC:
return add_rtattr(m, type, data, strlen(data) + 1);
case IFLA_MTU:
return add_rtattr(m, type, data, sizeof(uint32_t));
case IFLA_LINK:
return add_rtattr(m, type, data, sizeof(uint32_t));
case IFLA_STATS:
return add_rtattr(m, type, data, sizeof(struct rtnl_link_stats));
case IFLA_ADDRESS:
case IFLA_BROADCAST:
return add_rtattr(m, type, data, ETH_ALEN);
default:
return -ENOTSUP;
}
case RTM_NEWADDR:
case RTM_DELADDR:
case RTM_GETADDR:
switch (type) {
case IFA_LABEL:
return add_rtattr(m, type, data, strlen(data) + 1);
case IFA_ADDRESS:
case IFA_LOCAL:
case IFA_BROADCAST:
case IFA_ANYCAST:
ifa = NLMSG_DATA(m->hdr);
switch (ifa->ifa_family) {
case AF_INET:
return add_rtattr(m, type, data, sizeof(struct in_addr));
case AF_INET6:
return add_rtattr(m, type, data, sizeof(struct in6_addr));
default:
return -EINVAL;
}
default:
return -ENOTSUP;
}
case RTM_NEWROUTE:
case RTM_DELROUTE:
case RTM_GETROUTE:
switch (type) {
case RTA_DST:
case RTA_SRC:
case RTA_GATEWAY:
rtm = NLMSG_DATA(m->hdr);
switch (rtm->rtm_family) {
case AF_INET:
return add_rtattr(m, type, data, sizeof(struct in_addr));
case AF_INET6:
return add_rtattr(m, type, data, sizeof(struct in6_addr));
default:
return -EINVAL;
}
case RTA_TABLE:
case RTA_PRIORITY:
case RTA_IIF:
case RTA_OIF:
return add_rtattr(m, type, data, sizeof(uint32_t));
default:
return -ENOTSUP;
}
default:
return -ENOTSUP;
}
}
static int message_read(sd_rtnl_message *m, unsigned short *type, void **data) {
assert_return(m, -EINVAL);
assert_return(data, -EINVAL);
if (!RTA_OK(m->next_rta, m->remaining_size))
return 0;
*data = RTA_DATA(m->next_rta);
*type = m->next_rta->rta_type;
m->next_rta = RTA_NEXT(m->next_rta, m->remaining_size);
return 1;
}
int sd_rtnl_message_read(sd_rtnl_message *m, unsigned short *type, void **data) {
uint16_t rtm_type;
assert_return(m, -EINVAL);
assert_return(data, -EINVAL);
sd_rtnl_message_get_type(m, &rtm_type);
switch (rtm_type) {
case RTM_NEWLINK:
case RTM_DELLINK:
case RTM_GETLINK:
if (!m->next_rta) {
struct ifinfomsg *ifi = NLMSG_DATA(m->hdr);
m->next_rta = IFLA_RTA(ifi);
m->remaining_size = IFLA_PAYLOAD(m->hdr);
}
break;
case RTM_NEWADDR:
case RTM_DELADDR:
case RTM_GETADDR:
if (!m->next_rta) {
struct ifaddrmsg *ifa = NLMSG_DATA(m->hdr);
m->next_rta = IFA_RTA(ifa);
m->remaining_size = IFA_PAYLOAD(m->hdr);
}
break;
case RTM_NEWROUTE:
case RTM_DELROUTE:
case RTM_GETROUTE:
if (!m->next_rta) {
struct rtmesg *rtm = NLMSG_DATA(m->hdr);
m->next_rta = RTM_RTA(rtm);
m->remaining_size = RTM_PAYLOAD(m->hdr);
}
break;
default:
return -ENOTSUP;
}
return message_read(m, type, data);
}
int message_get_serial(sd_rtnl_message *m) {
assert(m);
return m->hdr->nlmsg_seq;
}
int message_get_errno(sd_rtnl_message *m) {
struct nlmsgerr *err;
assert(m);
if (m->hdr->nlmsg_type != NLMSG_ERROR)
return 0;
err = NLMSG_DATA(m->hdr);
return err->error;
}
int message_seal(sd_rtnl *nl, sd_rtnl_message *m) {
if (m->sealed)
return -EPERM;
m->hdr->nlmsg_seq = nl->serial++;
m->sealed = true;
return 0;
}
static int message_receive_need(sd_rtnl *rtnl, size_t *need) {
assert_return(rtnl, -EINVAL);
assert_return(need, -EINVAL);
/* ioctl(rtnl->fd, FIONREAD, &need)
Does not appear to work on netlink sockets. libnl uses
MSG_PEEK instead. I don't know if that is worth the
extra roundtrip.
For now we simply use the maximum message size the kernel
may use (NLMSG_GOODSIZE), and then realloc to the actual
size after reading the message (hence avoiding huge memory
usage in case many small messages are kept around) */
*need = page_size();
if (*need > 8192UL)
*need = 8192UL;
return 0;
}
/* returns the number of bytes sent, or a negative error code */
int socket_write_message(sd_rtnl *nl, sd_rtnl_message *m) {
union {
struct sockaddr sa;
struct sockaddr_nl nl;
} addr = {
.nl.nl_family = AF_NETLINK,
};
ssize_t k;
assert_return(nl, -EINVAL);
assert_return(m, -EINVAL);
k = sendto(nl->fd, m->hdr, m->hdr->nlmsg_len,
0, &addr.sa, sizeof(addr));
if (k < 0)
return (errno == EAGAIN) ? 0 : -errno;
return k;
}
/* On success, the number of bytes received is returned and *ret points to the received message
* which has a valid header and the correct size.
* If nothing useful was received 0 is returned.
* On failure, a negative error code is returned.
*/
int socket_read_message(sd_rtnl *nl, sd_rtnl_message **ret) {
sd_rtnl_message *m;
union {
struct sockaddr sa;
struct sockaddr_nl nl;
} addr;
socklen_t addr_len;
int r;
ssize_t k;
size_t need;
assert_return(nl, -EINVAL);
assert_return(ret, -EINVAL);
r = message_receive_need(nl, &need);
if (r < 0)
return r;
r = message_new(&m, need);
if (r < 0)
return r;
addr_len = sizeof(addr);
k = recvfrom(nl->fd, m->hdr, need,
0, &addr.sa, &addr_len);
if (k < 0)
k = (errno == EAGAIN) ? 0 : -errno; /* no data */
else if (k == 0)
k = -ECONNRESET; /* connection was closed by the kernel */
else if (addr_len != sizeof(addr.nl) ||
addr.nl.nl_family != AF_NETLINK)
k = -EIO; /* not a netlink message */
else if (addr.nl.nl_pid != 0)
k = 0; /* not from the kernel */
else if ((size_t) k < sizeof(struct nlmsghdr) ||
(size_t) k < m->hdr->nlmsg_len)
k = -EIO; /* too small (we do accept too big though) */
else if (m->hdr->nlmsg_pid != nl->sockaddr.nl.nl_pid)
k = 0; /* not for us */
if (k > 0)
switch (m->hdr->nlmsg_type) {
/* check that the size matches the message type */
case NLMSG_ERROR:
if (m->hdr->nlmsg_len < NLMSG_LENGTH(sizeof(struct nlmsgerr)))
k = -EIO;
break;
case RTM_NEWLINK:
case RTM_DELLINK:
case RTM_GETLINK:
if (m->hdr->nlmsg_len < NLMSG_LENGTH(sizeof(struct ifinfomsg)))
k = -EIO;
break;
case RTM_NEWADDR:
case RTM_DELADDR:
case RTM_GETADDR:
if (m->hdr->nlmsg_len < NLMSG_LENGTH(sizeof(struct ifaddrmsg)))
k = -EIO;
break;
case NLMSG_NOOP:
k = 0;
break;
default:
k = 0; /* ignoring message of unknown type */
}
if (k <= 0)
sd_rtnl_message_unref(m);
else {
/* we probably allocated way too much memory, give it back */
m->hdr = realloc(m->hdr, m->hdr->nlmsg_len);
*ret = m;
}
return k;
}