diff options
Diffstat (limited to 'src/core/loopback-setup.c')
| -rw-r--r-- | src/core/loopback-setup.c | 317 |
1 files changed, 317 insertions, 0 deletions
diff --git a/src/core/loopback-setup.c b/src/core/loopback-setup.c new file mode 100644 index 0000000000..065b75a6e3 --- /dev/null +++ b/src/core/loopback-setup.c @@ -0,0 +1,317 @@ +/*-*- 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 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 <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; + + l = sendto(fd, buf, buf_len, flags, sa, sa_len); + if (l >= 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; + + l = recvfrom(fd, buf, buf_len, flags, sa, sa_len); + if (l >= 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; + + r = add_rtattr(&request.header, sizeof(request), IFA_LOCAL, &ipv4_address, sizeof(ipv4_address)); + if (r < 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; + + r = add_rtattr(&request.header, sizeof(request), IFA_LOCAL, &in6addr_loopback, sizeof(in6addr_loopback)); + if (r < 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; + + l = recvfrom_loop(fd, &response, sizeof(response), 0, &sa.sa, &sa_len); + if (l < 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) + return nlmsgerr->error; + + return response.header.nlmsg_seq; +} + +static int check_loopback(void) { + int r, fd; + union { + struct sockaddr sa; + struct sockaddr_in in; + } sa; + + /* If we failed to set up the loop back device, check whether + * it might already be set up */ + + fd = socket(AF_INET, SOCK_DGRAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0); + if (fd < 0) + return -errno; + + zero(sa); + sa.in.sin_family = AF_INET; + sa.in.sin_addr.s_addr = INADDR_LOOPBACK; + + if (bind(fd, &sa.sa, sizeof(sa.in)) >= 0) + r = 1; + else + r = errno == EADDRNOTAVAIL ? 0 : -errno; + + close_nointr_nofail(fd); + + return r; +} + +int loopback_setup(void) { + int r, if_loopback; + union { + struct sockaddr sa; + struct sockaddr_nl nl; + } sa; + unsigned requests = 0, i; + int fd; + bool eperm = false; + + errno = 0; + if_loopback = (int) if_nametoindex("lo"); + if (if_loopback <= 0) + return errno ? -errno : -ENODEV; + + fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE); + if (fd < 0) + return -errno; + + zero(sa); + sa.nl.nl_family = AF_NETLINK; + if (bind(fd, &sa.sa, sizeof(sa)) < 0) { + r = -errno; + goto finish; + } + + r = add_adresses(fd, if_loopback, &requests); + if (r < 0) + goto finish; + + r = start_interface(fd, if_loopback, &requests); + if (r < 0) + goto finish; + + for (i = 0; i < requests; i++) { + r = read_response(fd, requests); + + if (r == -EPERM) + eperm = true; + else if (r < 0) + goto finish; + } + + if (eperm && check_loopback() < 0) { + r = -EPERM; + goto finish; + } + + r = 0; + +finish: + if (r < 0) + log_warning("Failed to configure loopback device: %s", strerror(-r)); + + if (fd >= 0) + close_nointr_nofail(fd); + + return r; +} |