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ndhc/ifchd/linux.c

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8.7 KiB
C
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/* linux.c - ifchd Linux-specific functions
* Time-stamp: <2011-05-31 11:54:30 njk>
*
* (C) 2004-2011 Nicholas J. Kain <njkain at gmail dot com>
*
* This program 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.
*
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#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 <pwd.h>
#include <grp.h>
#include <errno.h>
#include "ifchd-defines.h"
#include "log.h"
#include "strlist.h"
#include "ifproto.h"
#include "strl.h"
/* Symbolic name of the interface associated with a connection. */
static char ifnam[SOCK_QUEUE][IFNAMSIZ];
static strlist_t *okif;
/* Clear a specified ifnam structure. */
void clear_if_data(int idx)
{
memset(ifnam[idx], '\0', IFNAMSIZ);
}
/* Clear all ifnam structures. */
void initialize_if_data(void)
{
int i;
for (i = 0; i < SOCK_QUEUE; i++) {
clear_if_data(i);
}
}
/* Adds to the list of interface names ifchd clients are allowed to change. */
void add_permitted_if(char *s)
{
if (!s)
return;
add_to_strlist(&okif, s);
}
/* Checks if changes are permitted to a given interface. 1 == allowed */
static int is_permitted(char *name)
{
strlist_t *p;
/* If empty, permit all. */
if (!okif)
return 1;
if (!name || strlen(name) == 0)
return 0;
p = okif;
while (p) {
if (strcmp(name, p->str) == 0)
return 1;
p = p->next;
}
log_line("attempt to modify interface %s denied\n", 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\n", strerror(errno));
return ret;
}
void perform_interface(int idx, char *str)
{
if (!str)
return;
/* Update interface name. */
memset(ifnam[idx], '\0', IFNAMSIZ);
strlcpy(ifnam[idx], str, IFNAMSIZ);
}
static int set_if_flag(int idx, short flag)
{
int fd, ret = -1;
struct ifreq ifrt;
if (!is_permitted(ifnam[idx]))
goto out0;
fd = socket(AF_INET, SOCK_DGRAM, 0);
if (fd == -1) {
log_line("%s: (set_if_flag) failed to open interface socket: %s\n",
ifnam[idx], strerror(errno));
goto out0;
}
strlcpy(ifrt.ifr_name, ifnam[idx], IFNAMSIZ);
if (ioctl(fd, SIOCGIFFLAGS, &ifrt) < 0) {
log_line("%s: unknown interface: %s\n", ifnam[idx], strerror(errno));
goto out1;
}
if (((ifrt.ifr_flags & flag ) ^ flag) & flag) {
strlcpy(ifrt.ifr_name, ifnam[idx], IFNAMSIZ);
ifrt.ifr_flags |= flag;
if (ioctl(fd, SIOCSIFFLAGS, &ifrt) < 0) {
log_line("%s: failed to set interface flags: %s\n",
ifnam[idx], strerror(errno));
goto out1;
}
} else
ret = 0;
out1:
close(fd);
out0:
return ret;
}
/* Sets IP address on an interface and brings it up. */
void perform_ip(int idx, char *str)
{
int fd;
struct in_addr ipaddr;
struct ifreq ifrt;
struct sockaddr_in sin;
if (!str)
return;
if (!is_permitted(ifnam[idx]))
return;
if (!inet_pton(AF_INET, str, &ipaddr))
return;
if (set_if_flag(idx, (IFF_UP | IFF_RUNNING)))
return;
strlcpy(ifrt.ifr_name, ifnam[idx], 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\n",
ifnam[idx], strerror(errno));
return;
}
if (ioctl(fd, SIOCSIFADDR, &ifrt) < 0)
log_line("%s: failed to configure IP: %s\n",
ifnam[idx], strerror(errno));
close(fd);
}
/* Sets the subnet mask on an interface. */
void perform_subnet(int idx, char *str)
{
int fd;
struct in_addr subnet;
struct ifreq ifrt;
struct sockaddr_in sin;
if (!str)
return;
if (!is_permitted(ifnam[idx]))
return;
if (!inet_pton(AF_INET, str, &subnet))
return;
strlcpy(ifrt.ifr_name, ifnam[idx], 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\n",
ifnam[idx], 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\n",
ifnam[idx], strerror(errno));
}
close(fd);
}
void perform_router(int idx, char *str)
{
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(ifnam[idx]))
return;
if (!inet_pton(AF_INET, str, &router))
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 = ifnam[idx];
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\n",
ifnam[idx], strerror(errno));
return;
}
if (ioctl(fd, SIOCADDRT, &rt)) {
if (errno != EEXIST)
log_line("%s: failed to set route: %s\n",
ifnam[idx], strerror(errno));
}
close(fd);
}
void perform_mtu(int idx, char *str)
{
int fd;
unsigned int mtu;
struct ifreq ifrt;
if (!str)
return;
if (!is_permitted(ifnam[idx]))
return;
mtu = strtol(str, NULL, 10);
ifrt.ifr_mtu = mtu;
strlcpy(ifrt.ifr_name, ifnam[idx], IFNAMSIZ);
fd = socket(AF_INET, SOCK_DGRAM, 0);
if (fd == -1) {
log_line("%s: (perform_mtu) failed to open interface socket: %s\n",
ifnam[idx], strerror(errno));
return;
}
if (ioctl(fd, SIOCSIFMTU, &ifrt) < 0)
log_line("%s: failed to set MTU (%d): %s\n", ifnam[idx], mtu,
strerror(errno));
close(fd);
}
void perform_broadcast(int idx, char *str)
{
int fd;
struct in_addr broadcast;
struct ifreq ifrt;
struct sockaddr_in sin;
if (!str)
return;
if (!is_permitted(ifnam[idx]))
return;
if (!inet_pton(AF_INET, str, &broadcast))
return;
strlcpy(ifrt.ifr_name, ifnam[idx], 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\n", ifnam[idx], strerror(errno));
return;
}
if (ioctl(fd, SIOCSIFBRDADDR, &ifrt) < 0)
log_line("%s: failed to set broadcast: %s\n",
ifnam[idx], strerror(errno));
close(fd);
}
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