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520ba6fd31
ndhc/ifchd/linux.c
Nicholas J. Kain 520ba6fd31 Mark function prototypes in ifchd/linux.h as extern. 
Update copyright dates and do some cosmetic changes, too.
2014-03-09 12:32:30 -04:00

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/* linux.c - ifchd Linux-specific functions
*
* Copyright (c) 2004-2014 Nicholas J. Kain <njkain at gmail dot com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define __USE_GNU 1
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <net/route.h>
#include <net/if.h>
#include <netpacket/packet.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <pwd.h>
#include <grp.h>
#include <errno.h>
#include "ifchd-defines.h"
#include "log.h"
#include "ifch_proto.h"
#include "strl.h"
extern struct ifchd_client clients[SOCK_QUEUE];
static size_t numokif;
static char okif[MAX_IFACES][IFNAMSIZ];
/* Adds to the list of interface names ifchd clients are allowed to change. */
void add_permitted_if(char *s)
{
if (numokif >= MAX_IFACES)
return;
strnkcpy(okif[numokif++], s, IFNAMSIZ);
}
/* Checks if changes are permitted to a given interface. 1 == allowed */
static int is_permitted(char *name)
{
/* If empty, permit all. */
if (!numokif)
return 1;
if (!name || strlen(name) == 0)
return 0;
for (size_t i = 0; i < numokif; ++i) {
if (strcmp(name, okif[i]) == 0)
return 1;
}
log_line("attempt to modify interface %s denied", name);
return 0;
}
/* Verify that peer is authorized to connect (return 1 on success). */
int authorized_peer(int sk, pid_t pid, uid_t uid, gid_t gid)
{
int ret = 0;
unsigned int cl;
struct ucred cr;
/* No credentials to verify. */
if ( !(pid || uid || gid) )
return 1;
/* Verify that peer has authorized uid/gid/pid. */
cl = sizeof(struct ucred);
if (getsockopt(sk, SOL_SOCKET, SO_PEERCRED, &cr, &cl) != -1) {
if ((pid == 0 || cr.pid == pid) ||
(uid == 0 || cr.uid == uid) ||
(gid == 0 || cr.gid == gid))
ret = 1;
} else
log_line("getsockopt returned an error: %s", strerror(errno));
return ret;
}
void perform_interface(struct ifchd_client *cl, const char *str, size_t len)
{
if (!str)
return;
/* Update interface name. */
memset(cl->ifnam, '\0', IFNAMSIZ);
strnkcpy(cl->ifnam, str, IFNAMSIZ);
log_line("Subsequent commands alter interface: '%s'", str);
}
static int set_if_flag(struct ifchd_client *cl, short flag)
{
int fd, ret = -1;
struct ifreq ifrt;
if (!is_permitted(cl->ifnam))
goto out0;
fd = socket(AF_INET, SOCK_DGRAM, 0);
if (fd == -1) {
log_line("%s: (set_if_flag) failed to open interface socket: %s",
cl->ifnam, strerror(errno));
goto out0;
}
strnkcpy(ifrt.ifr_name, cl->ifnam, IFNAMSIZ);
if (ioctl(fd, SIOCGIFFLAGS, &ifrt) < 0) {
log_line("%s: unknown interface: %s", cl->ifnam, strerror(errno));
goto out1;
}
if (((ifrt.ifr_flags & flag ) ^ flag) & flag) {
strnkcpy(ifrt.ifr_name, cl->ifnam, IFNAMSIZ);
ifrt.ifr_flags |= flag;
if (ioctl(fd, SIOCSIFFLAGS, &ifrt) < 0) {
log_line("%s: failed to set interface flags: %s",
cl->ifnam, strerror(errno));
goto out1;
}
} else
ret = 0;
out1:
close(fd);
out0:
return ret;
}
#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 int get_ifindex(const char *name)
{
struct ifreq ifr;
int sk, err;
if (!name)
return -1;
sk = socket(PF_INET, SOCK_DGRAM, 0);
if (sk < 0)
return -1;
memset(&ifr, 0, sizeof ifr);
strnkcpy(ifr.ifr_name, name, sizeof ifr.ifr_name);
err = ioctl(sk, SIOCGIFINDEX, &ifr);
close(sk);
if (err < 0)
return -1;
return ifr.ifr_ifindex;
}
// 32-bit position values are relatively prime to 37, so the residue mod37
// gives a unique mapping for each value. Gives correct result for v=0.
static int trailz(uint32_t v)
{
static const int bpm37[] = {
32, 0, 1, 26, 2, 23, 27, 0, 3, 16, 24, 30, 28, 11, 0, 13, 4, 7, 17,
0, 25, 22, 31, 15, 29, 10, 12, 6, 0, 21, 14, 9, 5, 20, 8, 19, 18
};
return bpm37[(-v & v) % 37];
}
// sn must be in network order
static inline int subnet4_to_prefixlen(uint32_t sn)
{
return 32 - trailz(sn);
}
// str_bcast is optional.
void perform_ip_subnet_bcast(struct ifchd_client *cl, const char *str_ipaddr,
const char *str_subnet, const char *str_bcast)
{
uint8_t request[NLMSG_ALIGN(sizeof(struct nlmsghdr)) +
NLMSG_ALIGN(sizeof(struct ifaddrmsg)) +
RTA_LENGTH(sizeof(struct in6_addr))];
struct in_addr ipaddr, subnet, bcast;
struct sockaddr_nl nl_addr;
struct nlmsghdr *header;
struct ifaddrmsg *ifaddrmsg;
int nls, ifidx, r;
uint8_t prefixlen;
if (!str_ipaddr) {
log_line("%s: (%s) interface ip address is NULL",
cl->ifnam, __func__);
return;
}
if (!str_subnet) {
log_line("%s: (%s) interface subnet address is NULL",
cl->ifnam, __func__);
return;
}
if (!is_permitted(cl->ifnam))
return;
ifidx = get_ifindex(cl->ifnam);
if (ifidx < 0) {
log_line("%s: (%s) can't get interface index",
cl->ifnam, __func__);
return;
}
if (inet_pton(AF_INET, str_ipaddr, &ipaddr) <= 0) {
log_line("%s: (%s) bad interface ip address: '%s'",
cl->ifnam, __func__, str_ipaddr);
return;
}
if (inet_pton(AF_INET, str_subnet, &subnet) <= 0) {
log_line("%s: (%s) bad interface subnet address: '%s'",
cl->ifnam, __func__, str_subnet);
return;
}
prefixlen = subnet4_to_prefixlen(subnet.s_addr);
if (str_bcast) {
if (inet_pton(AF_INET, str_bcast, &bcast) <= 0) {
log_line("%s: (%s) bad interface broadcast address: '%s'",
cl->ifnam, __func__, str_bcast);
return;
}
} else {
// Generate the standard broadcast address if unspecified.
bcast.s_addr = ipaddr.s_addr | htonl(0xfffffffflu >> prefixlen);
}
memset(&request, 0, sizeof request);
header = (struct nlmsghdr *)request;
header->nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg));
header->nlmsg_type = RTM_NEWADDR;
header->nlmsg_flags = NLM_F_REPLACE | NLM_F_ACK | NLM_F_REQUEST;
header->nlmsg_seq = 1;
ifaddrmsg = NLMSG_DATA(header);
ifaddrmsg->ifa_family = AF_INET;
ifaddrmsg->ifa_prefixlen = prefixlen;
ifaddrmsg->ifa_flags = IFA_F_PERMANENT;
ifaddrmsg->ifa_scope = RT_SCOPE_UNIVERSE;
ifaddrmsg->ifa_index = ifidx;
if (add_rtattr(header, sizeof request, IFA_LOCAL,
&ipaddr, sizeof ipaddr) < 0) {
log_line("%s: (%s) couldn't add IFA_LOCAL to nlmsg",
cl->ifnam, __func__);
return;
}
if (add_rtattr(header, sizeof request, IFA_BROADCAST,
&bcast, sizeof bcast) < 0) {
log_line("%s: (%s) couldn't add IFA_BROADCAST to nlmsg",
cl->ifnam, __func__);
return;
}
nls = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
if (nls < 0) {
log_line("%s: (%s) netlink socket open failed: %s",
cl->ifnam, __func__, strerror(errno));
return;
}
memset(&nl_addr, 0, sizeof nl_addr);
nl_addr.nl_family = AF_NETLINK;
retry_sendto:
r = sendto(nls, request, header->nlmsg_len, 0,
(struct sockaddr *)&nl_addr, sizeof nl_addr);
if (r < 0) {
if (errno == EINTR)
goto retry_sendto;
else {
log_line("%s: (%s) netlink sendto socket failed: %s",
cl->ifnam, __func__, strerror(errno));
close(nls);
return;
}
}
close(nls);
log_line("Interface IP set to: '%s'", str_ipaddr);
log_line("Interface subnet set to: '%s'", str_subnet);
if (str_bcast)
log_line("Broadcast address set to: '%s'", str_bcast);
// XXX: Would be nice to do this via netlink, too.
if (set_if_flag(cl, (IFF_UP | IFF_RUNNING)))
return;
}
/* Sets IP address on an interface and brings it up. */
void perform_ip(struct ifchd_client *cl, const char *str, size_t len)
{
int fd;
struct in_addr ipaddr;
struct ifreq ifrt;
struct sockaddr_in sin;
if (!str)
return;
if (!is_permitted(cl->ifnam))
return;
if (inet_pton(AF_INET, str, &ipaddr) <= 0)
return;
if (set_if_flag(cl, (IFF_UP | IFF_RUNNING)))
return;
strnkcpy(ifrt.ifr_name, cl->ifnam, IFNAMSIZ);
memset(&sin, 0, sizeof(struct sockaddr));
sin.sin_family = AF_INET;
sin.sin_addr = ipaddr;
memcpy(&ifrt.ifr_addr, &sin, sizeof(struct sockaddr));
fd = socket(AF_INET, SOCK_DGRAM, 0);
if (fd == -1) {
log_line("%s: (perform_ip) failed to open interface socket: %s",
cl->ifnam, strerror(errno));
return;
}
if (ioctl(fd, SIOCSIFADDR, &ifrt) < 0)
log_line("%s: failed to configure IP: %s",
cl->ifnam, strerror(errno));
else
log_line("Interface IP set to: '%s'", str);
close(fd);
}
/* Sets the subnet mask on an interface. */
void perform_subnet(struct ifchd_client *cl, const char *str, size_t len)
{
int fd;
struct in_addr subnet;
struct ifreq ifrt;
struct sockaddr_in sin;
if (!str)
return;
if (!is_permitted(cl->ifnam))
return;
if (inet_pton(AF_INET, str, &subnet) <= 0)
return;
strnkcpy(ifrt.ifr_name, cl->ifnam, IFNAMSIZ);
memset(&sin, 0, sizeof(struct sockaddr));
sin.sin_family = AF_INET;
sin.sin_addr = subnet;
memcpy(&ifrt.ifr_addr, &sin, sizeof(struct sockaddr));
fd = socket(AF_INET, SOCK_DGRAM, 0);
if (fd == -1) {
log_line("%s: (perform_ip) failed to open interface socket: %s",
cl->ifnam, strerror(errno));
return;
}
if (ioctl(fd, SIOCSIFNETMASK, &ifrt) < 0) {
sin.sin_addr.s_addr = 0xffffffff;
if (ioctl(fd, SIOCSIFNETMASK, &ifrt) < 0)
log_line("%s: failed to configure subnet: %s",
cl->ifnam, strerror(errno));
} else
log_line("Interface subnet set to: '%s'", str);
close(fd);
}
void perform_router(struct ifchd_client *cl, const char *str, size_t len)
{
struct rtentry rt;
struct sockaddr_in *dest;
struct sockaddr_in *gateway;
struct sockaddr_in *mask;
struct in_addr router;
int fd;
if (!str)
return;
if (!is_permitted(cl->ifnam))
return;
if (inet_pton(AF_INET, str, &router) <= 0)
return;
memset(&rt, 0, sizeof(struct rtentry));
dest = (struct sockaddr_in *) &rt.rt_dst;
dest->sin_family = AF_INET;
dest->sin_addr.s_addr = 0x00000000;
gateway = (struct sockaddr_in *) &rt.rt_gateway;
gateway->sin_family = AF_INET;
gateway->sin_addr = router;
mask = (struct sockaddr_in *) &rt.rt_genmask;
mask->sin_family = AF_INET;
mask->sin_addr.s_addr = 0x00000000;
rt.rt_flags = RTF_UP | RTF_GATEWAY;
if (mask->sin_addr.s_addr == 0xffffffff) rt.rt_flags |= RTF_HOST;
rt.rt_dev = cl->ifnam;
rt.rt_metric = 1;
fd = socket(AF_INET, SOCK_DGRAM, 0);
if (fd == -1) {
log_line("%s: (perform_router) failed to open interface socket: %s",
cl->ifnam, strerror(errno));
return;
}
if (ioctl(fd, SIOCADDRT, &rt)) {
if (errno != EEXIST)
log_line("%s: failed to set route: %s",
cl->ifnam, strerror(errno));
} else
log_line("Gateway router set to: '%s'", str);
close(fd);
}
void perform_mtu(struct ifchd_client *cl, const char *str, size_t len)
{
int fd;
unsigned int mtu;
struct ifreq ifrt;
if (!str)
return;
if (!is_permitted(cl->ifnam))
return;
mtu = strtol(str, NULL, 10);
// Minimum MTU for physical IPv4 links is 576 octets.
if (mtu < 576)
return;
ifrt.ifr_mtu = mtu;
strnkcpy(ifrt.ifr_name, cl->ifnam, IFNAMSIZ);
fd = socket(AF_INET, SOCK_DGRAM, 0);
if (fd == -1) {
log_line("%s: (perform_mtu) failed to open interface socket: %s",
cl->ifnam, strerror(errno));
return;
}
if (ioctl(fd, SIOCSIFMTU, &ifrt) < 0)
log_line("%s: failed to set MTU (%d): %s", cl->ifnam, mtu,
strerror(errno));
else
log_line("MTU set to: '%s'", str);
close(fd);
}
void perform_broadcast(struct ifchd_client *cl, const char *str, size_t len)
{
int fd;
struct in_addr broadcast;
struct ifreq ifrt;
struct sockaddr_in sin;
if (!str)
return;
if (!is_permitted(cl->ifnam))
return;
if (inet_pton(AF_INET, str, &broadcast) <= 0)
return;
strnkcpy(ifrt.ifr_name, cl->ifnam, IFNAMSIZ);
memset(&sin, 0, sizeof(struct sockaddr));
sin.sin_family = AF_INET;
sin.sin_addr = broadcast;
memcpy(&ifrt.ifr_addr, &sin, sizeof(struct sockaddr));
fd = socket(AF_INET, SOCK_DGRAM, 0);
if (fd == -1) {
log_line("%s: (perform_broadcast) failed to open interface socket: %s", cl->ifnam, strerror(errno));
return;
}
if (ioctl(fd, SIOCSIFBRDADDR, &ifrt) < 0)
log_line("%s: failed to set broadcast: %s",
cl->ifnam, strerror(errno));
else
log_line("Broadcast address set to: '%s'", str);
close(fd);
}
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