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Systemd/src/loopback-setup.c
Fabiano Fidencio 5bfcc1c6ef socket: Support IPv6-less systems with runtime check. 
This patch introduces socket_ipv6_is_supported() call that checks for
IPv6 availability. Code then check for it before using specific calls.

In order to be less intrusive, this patch avoids IPv6 entries being
parsed at all, this way we don't get such entries in the system and
all other code paths are automatically ignored. However an extra check
is done at socket_address_listen() to make sure of that.

As the number of Netlink messages is not know upfront anymore,
loopback-setup.c was refactored to dynamically calculate the sequence
number and count.

Lennart's suggestions were fixed and squashed with the original patch,
that was sent by Gustavo Sverzut Barbieri (barbieri@profusion.mobi).
2010-09-21 01:00:38 +02:00

275 lines
8.3 KiB
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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd 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 2 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
General Public License for more details.
You should have received a copy of the GNU General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <errno.h>
#include <sys/socket.h>
#include <net/if.h>
#include <asm/types.h>
#include <netinet/in.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include "util.h"
#include "macro.h"
#include "loopback-setup.h"
#include "socket-util.h"
#define NLMSG_TAIL(nmsg) \
((struct rtattr *) (((uint8_t*) (nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len)))
static int add_rtattr(struct nlmsghdr *n, size_t max_length, int type, const void *data, size_t data_length) {
size_t length;
struct rtattr *rta;
length = RTA_LENGTH(data_length);
if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(length) > max_length)
return -E2BIG;
rta = NLMSG_TAIL(n);
rta->rta_type = type;
rta->rta_len = length;
memcpy(RTA_DATA(rta), data, data_length);
n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(length);
return 0;
}
static ssize_t sendto_loop(int fd, const void *buf, size_t buf_len, int flags, const struct sockaddr *sa, socklen_t sa_len) {
for (;;) {
ssize_t l;
if ((l = sendto(fd, buf, buf_len, flags, sa, sa_len)) >= 0)
return l;
if (errno != EINTR)
return -errno;
}
}
static ssize_t recvfrom_loop(int fd, void *buf, size_t buf_len, int flags, struct sockaddr *sa, socklen_t *sa_len) {
for (;;) {
ssize_t l;
if ((l = recvfrom(fd, buf, buf_len, flags, sa, sa_len)) >= 0)
return l;
if (errno != EINTR)
return -errno;
}
}
static int add_adresses(int fd, int if_loopback, unsigned *requests) {
union {
struct sockaddr sa;
struct sockaddr_nl nl;
} sa;
union {
struct nlmsghdr header;
uint8_t buf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) +
NLMSG_ALIGN(sizeof(struct ifaddrmsg)) +
RTA_LENGTH(sizeof(struct in6_addr))];
} request;
struct ifaddrmsg *ifaddrmsg;
uint32_t ipv4_address = htonl(INADDR_LOOPBACK);
int r;
zero(request);
request.header.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg));
request.header.nlmsg_type = RTM_NEWADDR;
request.header.nlmsg_flags = NLM_F_REQUEST|NLM_F_CREATE|NLM_F_ACK;
request.header.nlmsg_seq = *requests + 1;
ifaddrmsg = NLMSG_DATA(&request.header);
ifaddrmsg->ifa_family = AF_INET;
ifaddrmsg->ifa_prefixlen = 8;
ifaddrmsg->ifa_flags = IFA_F_PERMANENT;
ifaddrmsg->ifa_scope = RT_SCOPE_HOST;
ifaddrmsg->ifa_index = if_loopback;
if ((r = add_rtattr(&request.header, sizeof(request), IFA_LOCAL, &ipv4_address, sizeof(ipv4_address))) < 0)
return r;
zero(sa);
sa.nl.nl_family = AF_NETLINK;
if (sendto_loop(fd, &request, request.header.nlmsg_len, 0, &sa.sa, sizeof(sa)) < 0)
return -errno;
(*requests)++;
if (!socket_ipv6_is_supported())
return 0;
request.header.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg));
request.header.nlmsg_seq = *requests + 1;
ifaddrmsg->ifa_family = AF_INET6;
ifaddrmsg->ifa_prefixlen = 128;
if ((r = add_rtattr(&request.header, sizeof(request), IFA_LOCAL, &in6addr_loopback, sizeof(in6addr_loopback))) < 0)
return r;
if (sendto_loop(fd, &request, request.header.nlmsg_len, 0, &sa.sa, sizeof(sa)) < 0)
return -errno;
(*requests)++;
return 0;
}
static int start_interface(int fd, int if_loopback, unsigned *requests) {
union {
struct sockaddr sa;
struct sockaddr_nl nl;
} sa;
union {
struct nlmsghdr header;
uint8_t buf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) +
NLMSG_ALIGN(sizeof(struct ifinfomsg))];
} request;
struct ifinfomsg *ifinfomsg;
zero(request);
request.header.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
request.header.nlmsg_type = RTM_NEWLINK;
request.header.nlmsg_flags = NLM_F_REQUEST|NLM_F_ACK;
request.header.nlmsg_seq = *requests + 1;
ifinfomsg = NLMSG_DATA(&request.header);
ifinfomsg->ifi_family = AF_UNSPEC;
ifinfomsg->ifi_index = if_loopback;
ifinfomsg->ifi_flags = IFF_UP;
ifinfomsg->ifi_change = IFF_UP;
zero(sa);
sa.nl.nl_family = AF_NETLINK;
if (sendto_loop(fd, &request, request.header.nlmsg_len, 0, &sa.sa, sizeof(sa)) < 0)
return -errno;
(*requests)++;
return 0;
}
static int read_response(int fd, unsigned requests_max) {
union {
struct sockaddr sa;
struct sockaddr_nl nl;
} sa;
union {
struct nlmsghdr header;
uint8_t buf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) +
NLMSG_ALIGN(sizeof(struct nlmsgerr))];
} response;
ssize_t l;
socklen_t sa_len = sizeof(sa);
struct nlmsgerr *nlmsgerr;
if ((l = recvfrom_loop(fd, &response, sizeof(response), 0, &sa.sa, &sa_len)) < 0)
return -errno;
if (sa_len != sizeof(sa.nl) ||
sa.nl.nl_family != AF_NETLINK)
return -EIO;
if (sa.nl.nl_pid != 0)
return 0;
if ((size_t) l < sizeof(struct nlmsghdr))
return -EIO;
if (response.header.nlmsg_type != NLMSG_ERROR ||
(pid_t) response.header.nlmsg_pid != getpid() ||
response.header.nlmsg_seq >= requests_max)
return 0;
if ((size_t) l < NLMSG_LENGTH(sizeof(struct nlmsgerr)) ||
response.header.nlmsg_len < NLMSG_LENGTH(sizeof(struct nlmsgerr)))
return -EIO;
nlmsgerr = NLMSG_DATA(&response.header);
if (nlmsgerr->error < 0 && nlmsgerr->error != -EEXIST) {
log_warning("Netlink failure for request %i: %s", response.header.nlmsg_seq, strerror(-nlmsgerr->error));
return nlmsgerr->error;
}
return response.header.nlmsg_seq;
}
int loopback_setup(void) {
int r, if_loopback;
union {
struct sockaddr sa;
struct sockaddr_nl nl;
struct sockaddr_storage storage;
} sa;
unsigned requests = 0, i;
int fd;
errno = 0;
if ((if_loopback = (int) if_nametoindex("lo")) <= 0)
return errno ? -errno : -ENODEV;
if ((fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE)) < 0)
return -errno;
zero(sa);
sa.nl.nl_family = AF_NETLINK;
if (bind(fd, &sa.sa, sizeof(sa)) < 0) {
r = -errno;
goto finish;
}
if ((r = add_adresses(fd, if_loopback, &requests)) < 0)
goto finish;
if ((r = start_interface(fd, if_loopback, &requests)) < 0)
goto finish;
for (i = 0; i < requests; i++) {
if ((r = read_response(fd, requests)) < 0)
goto finish;
}
r = 0;
finish:
if (r < 0)
log_error("Failed to configure loopback device: %s", strerror(-r));
if (fd >= 0)
close_nointr_nofail(fd);
return r;
}
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