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mirror_iproute2/ip/iptunnel.c
Phil Sutter 625df645b7 Check user supplied interface name lengths 
The original problem was that something like:

| strncpy(ifr.ifr_name, *argv, IFNAMSIZ);

might leave ifr.ifr_name unterminated if length of *argv exceeds
IFNAMSIZ. In order to fix this, I thought about replacing all those
cases with (equivalent) calls to snprintf() or even introducing
strlcpy(). But as Ulrich Drepper correctly pointed out when rejecting
the latter from being added to glibc, truncating a string without
notifying the user is not to be considered good practice. So let's
excercise what he suggested and reject empty, overlong or otherwise
invalid interface names right from the start - this way calls to
strncpy() like shown above become safe and the user has a chance to
reconsider what he was trying to do.

Note that this doesn't add calls to check_ifname() to all places where
user supplied interface name is parsed. In many cases, the interface
must exist already and is therefore looked up using ll_name_to_index(),
so if_nametoindex() will perform the necessary checks already.

Signed-off-by: Phil Sutter <phil@nwl.cc>
2017-10-02 08:01:21 -07:00

628 lines
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/*
* iptunnel.c "ip tunnel"
*
* 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.
*
* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <linux/ip.h>
#include <linux/if_tunnel.h>
#include "rt_names.h"
#include "utils.h"
#include "ip_common.h"
#include "tunnel.h"
static void usage(void) __attribute__((noreturn));
static void usage(void)
{
fprintf(stderr, "Usage: ip tunnel { add | change | del | show | prl | 6rd } [ NAME ]\n");
fprintf(stderr, " [ mode { ipip | gre | sit | isatap | vti } ] [ remote ADDR ] [ local ADDR ]\n");
fprintf(stderr, " [ [i|o]seq ] [ [i|o]key KEY ] [ [i|o]csum ]\n");
fprintf(stderr, " [ prl-default ADDR ] [ prl-nodefault ADDR ] [ prl-delete ADDR ]\n");
fprintf(stderr, " [ 6rd-prefix ADDR ] [ 6rd-relay_prefix ADDR ] [ 6rd-reset ]\n");
fprintf(stderr, " [ ttl TTL ] [ tos TOS ] [ [no]pmtudisc ] [ dev PHYS_DEV ]\n");
fprintf(stderr, "\n");
fprintf(stderr, "Where: NAME := STRING\n");
fprintf(stderr, " ADDR := { IP_ADDRESS | any }\n");
fprintf(stderr, " TOS := { STRING | 00..ff | inherit | inherit/STRING | inherit/00..ff }\n");
fprintf(stderr, " TTL := { 1..255 | inherit }\n");
fprintf(stderr, " KEY := { DOTTED_QUAD | NUMBER }\n");
exit(-1);
}
static void set_tunnel_proto(struct ip_tunnel_parm *p, int proto)
{
if (p->iph.protocol && p->iph.protocol != proto) {
fprintf(stderr,
"You managed to ask for more than one tunnel mode.\n");
exit(-1);
}
p->iph.protocol = proto;
}
static int parse_args(int argc, char **argv, int cmd, struct ip_tunnel_parm *p)
{
int count = 0;
const char *medium = NULL;
int isatap = 0;
memset(p, 0, sizeof(*p));
p->iph.version = 4;
p->iph.ihl = 5;
#ifndef IP_DF
#define IP_DF 0x4000 /* Flag: "Don't Fragment" */
#endif
p->iph.frag_off = htons(IP_DF);
while (argc > 0) {
if (strcmp(*argv, "mode") == 0) {
NEXT_ARG();
if (strcmp(*argv, "ipip") == 0 ||
strcmp(*argv, "ip/ip") == 0) {
set_tunnel_proto(p, IPPROTO_IPIP);
} else if (strcmp(*argv, "gre") == 0 ||
strcmp(*argv, "gre/ip") == 0) {
set_tunnel_proto(p, IPPROTO_GRE);
} else if (strcmp(*argv, "sit") == 0 ||
strcmp(*argv, "ipv6/ip") == 0) {
set_tunnel_proto(p, IPPROTO_IPV6);
} else if (strcmp(*argv, "isatap") == 0) {
set_tunnel_proto(p, IPPROTO_IPV6);
isatap++;
} else if (strcmp(*argv, "vti") == 0) {
set_tunnel_proto(p, IPPROTO_IPIP);
p->i_flags |= VTI_ISVTI;
} else {
fprintf(stderr,
"Unknown tunnel mode \"%s\"\n", *argv);
exit(-1);
}
} else if (strcmp(*argv, "key") == 0) {
NEXT_ARG();
p->i_flags |= GRE_KEY;
p->o_flags |= GRE_KEY;
p->i_key = p->o_key = tnl_parse_key("key", *argv);
} else if (strcmp(*argv, "ikey") == 0) {
NEXT_ARG();
p->i_flags |= GRE_KEY;
p->i_key = tnl_parse_key("ikey", *argv);
} else if (strcmp(*argv, "okey") == 0) {
NEXT_ARG();
p->o_flags |= GRE_KEY;
p->o_key = tnl_parse_key("okey", *argv);
} else if (strcmp(*argv, "seq") == 0) {
p->i_flags |= GRE_SEQ;
p->o_flags |= GRE_SEQ;
} else if (strcmp(*argv, "iseq") == 0) {
p->i_flags |= GRE_SEQ;
} else if (strcmp(*argv, "oseq") == 0) {
p->o_flags |= GRE_SEQ;
} else if (strcmp(*argv, "csum") == 0) {
p->i_flags |= GRE_CSUM;
p->o_flags |= GRE_CSUM;
} else if (strcmp(*argv, "icsum") == 0) {
p->i_flags |= GRE_CSUM;
} else if (strcmp(*argv, "ocsum") == 0) {
p->o_flags |= GRE_CSUM;
} else if (strcmp(*argv, "nopmtudisc") == 0) {
p->iph.frag_off = 0;
} else if (strcmp(*argv, "pmtudisc") == 0) {
p->iph.frag_off = htons(IP_DF);
} else if (strcmp(*argv, "remote") == 0) {
NEXT_ARG();
if (strcmp(*argv, "any"))
p->iph.daddr = get_addr32(*argv);
else
p->iph.daddr = htonl(INADDR_ANY);
} else if (strcmp(*argv, "local") == 0) {
NEXT_ARG();
if (strcmp(*argv, "any"))
p->iph.saddr = get_addr32(*argv);
else
p->iph.saddr = htonl(INADDR_ANY);
} else if (strcmp(*argv, "dev") == 0) {
NEXT_ARG();
medium = *argv;
} else if (strcmp(*argv, "ttl") == 0 ||
strcmp(*argv, "hoplimit") == 0 ||
strcmp(*argv, "hlim") == 0) {
__u8 uval;
NEXT_ARG();
if (strcmp(*argv, "inherit") != 0) {
if (get_u8(&uval, *argv, 0))
invarg("invalid TTL\n", *argv);
p->iph.ttl = uval;
}
} else if (strcmp(*argv, "tos") == 0 ||
strcmp(*argv, "tclass") == 0 ||
matches(*argv, "dsfield") == 0) {
char *dsfield;
__u32 uval;
NEXT_ARG();
dsfield = *argv;
strsep(&dsfield, "/");
if (strcmp(*argv, "inherit") != 0) {
dsfield = *argv;
p->iph.tos = 0;
} else
p->iph.tos = 1;
if (dsfield) {
if (rtnl_dsfield_a2n(&uval, dsfield))
invarg("bad TOS value", *argv);
p->iph.tos |= uval;
}
} else {
if (strcmp(*argv, "name") == 0)
NEXT_ARG();
else if (matches(*argv, "help") == 0)
usage();
if (p->name[0])
duparg2("name", *argv);
if (get_ifname(p->name, *argv))
invarg("\"name\" not a valid ifname", *argv);
if (cmd == SIOCCHGTUNNEL && count == 0) {
struct ip_tunnel_parm old_p = {};
if (tnl_get_ioctl(*argv, &old_p))
return -1;
*p = old_p;
}
}
count++;
argc--; argv++;
}
if (p->iph.protocol == 0) {
if (memcmp(p->name, "gre", 3) == 0)
p->iph.protocol = IPPROTO_GRE;
else if (memcmp(p->name, "ipip", 4) == 0)
p->iph.protocol = IPPROTO_IPIP;
else if (memcmp(p->name, "sit", 3) == 0)
p->iph.protocol = IPPROTO_IPV6;
else if (memcmp(p->name, "isatap", 6) == 0) {
p->iph.protocol = IPPROTO_IPV6;
isatap++;
} else if (memcmp(p->name, "vti", 3) == 0) {
p->iph.protocol = IPPROTO_IPIP;
p->i_flags |= VTI_ISVTI;
}
}
if ((p->i_flags & GRE_KEY) || (p->o_flags & GRE_KEY)) {
if (!(p->i_flags & VTI_ISVTI) &&
(p->iph.protocol != IPPROTO_GRE)) {
fprintf(stderr, "Keys are not allowed with ipip and sit tunnels\n");
return -1;
}
}
if (medium) {
p->link = ll_name_to_index(medium);
if (p->link == 0) {
fprintf(stderr, "Cannot find device \"%s\"\n", medium);
return -1;
}
}
if (p->i_key == 0 && IN_MULTICAST(ntohl(p->iph.daddr))) {
p->i_key = p->iph.daddr;
p->i_flags |= GRE_KEY;
}
if (p->o_key == 0 && IN_MULTICAST(ntohl(p->iph.daddr))) {
p->o_key = p->iph.daddr;
p->o_flags |= GRE_KEY;
}
if (IN_MULTICAST(ntohl(p->iph.daddr)) && !p->iph.saddr) {
fprintf(stderr, "A broadcast tunnel requires a source address\n");
return -1;
}
if (isatap)
p->i_flags |= SIT_ISATAP;
return 0;
}
static const char *tnl_defname(const struct ip_tunnel_parm *p)
{
switch (p->iph.protocol) {
case IPPROTO_IPIP:
if (p->i_flags & VTI_ISVTI)
return "ip_vti0";
else
return "tunl0";
case IPPROTO_GRE:
return "gre0";
case IPPROTO_IPV6:
return "sit0";
}
return NULL;
}
static int do_add(int cmd, int argc, char **argv)
{
struct ip_tunnel_parm p;
const char *basedev;
if (parse_args(argc, argv, cmd, &p) < 0)
return -1;
if (p.iph.ttl && p.iph.frag_off == 0) {
fprintf(stderr, "ttl != 0 and nopmtudisc are incompatible\n");
return -1;
}
basedev = tnl_defname(&p);
if (!basedev) {
fprintf(stderr,
"cannot determine tunnel mode (ipip, gre, vti or sit)\n");
return -1;
}
return tnl_add_ioctl(cmd, basedev, p.name, &p);
}
static int do_del(int argc, char **argv)
{
struct ip_tunnel_parm p;
if (parse_args(argc, argv, SIOCDELTUNNEL, &p) < 0)
return -1;
return tnl_del_ioctl(tnl_defname(&p) ? : p.name, p.name, &p);
}
static void print_tunnel(struct ip_tunnel_parm *p)
{
struct ip_tunnel_6rd ip6rd = {};
char s1[1024];
char s2[1024];
/* Do not use format_host() for local addr,
* symbolic name will not be useful.
*/
printf("%s: %s/ip remote %s local %s",
p->name,
tnl_strproto(p->iph.protocol),
p->iph.daddr ? format_host_r(AF_INET, 4, &p->iph.daddr, s1, sizeof(s1)) : "any",
p->iph.saddr ? rt_addr_n2a_r(AF_INET, 4, &p->iph.saddr, s2, sizeof(s2)) : "any");
if (p->iph.protocol == IPPROTO_IPV6 && (p->i_flags & SIT_ISATAP)) {
struct ip_tunnel_prl prl[16] = {};
int i;
prl[0].datalen = sizeof(prl) - sizeof(prl[0]);
prl[0].addr = htonl(INADDR_ANY);
if (!tnl_prl_ioctl(SIOCGETPRL, p->name, prl))
for (i = 1; i < ARRAY_SIZE(prl); i++) {
if (prl[i].addr != htonl(INADDR_ANY)) {
printf(" %s %s ",
(prl[i].flags & PRL_DEFAULT) ? "pdr" : "pr",
format_host(AF_INET, 4, &prl[i].addr));
}
}
}
if (p->link) {
const char *n = ll_index_to_name(p->link);
if (n)
printf(" dev %s", n);
}
if (p->iph.ttl)
printf(" ttl %d", p->iph.ttl);
else
printf(" ttl inherit");
if (p->iph.tos) {
SPRINT_BUF(b1);
printf(" tos");
if (p->iph.tos & 1)
printf(" inherit");
if (p->iph.tos & ~1)
printf("%c%s ", p->iph.tos & 1 ? '/' : ' ',
rtnl_dsfield_n2a(p->iph.tos & ~1, b1, sizeof(b1)));
}
if (!(p->iph.frag_off & htons(IP_DF)))
printf(" nopmtudisc");
if (p->iph.protocol == IPPROTO_IPV6 && !tnl_ioctl_get_6rd(p->name, &ip6rd) && ip6rd.prefixlen) {
printf(" 6rd-prefix %s/%u",
inet_ntop(AF_INET6, &ip6rd.prefix, s1, sizeof(s1)),
ip6rd.prefixlen);
if (ip6rd.relay_prefix) {
printf(" 6rd-relay_prefix %s/%u",
format_host(AF_INET, 4, &ip6rd.relay_prefix),
ip6rd.relay_prefixlen);
}
}
if ((p->i_flags & GRE_KEY) && (p->o_flags & GRE_KEY) && p->o_key == p->i_key)
printf(" key %u", ntohl(p->i_key));
else if ((p->i_flags | p->o_flags) & GRE_KEY) {
if (p->i_flags & GRE_KEY)
printf(" ikey %u", ntohl(p->i_key));
if (p->o_flags & GRE_KEY)
printf(" okey %u", ntohl(p->o_key));
}
if (p->i_flags & GRE_SEQ)
printf("%s Drop packets out of sequence.", _SL_);
if (p->i_flags & GRE_CSUM)
printf("%s Checksum in received packet is required.", _SL_);
if (p->o_flags & GRE_SEQ)
printf("%s Sequence packets on output.", _SL_);
if (p->o_flags & GRE_CSUM)
printf("%s Checksum output packets.", _SL_);
}
static int do_tunnels_list(struct ip_tunnel_parm *p)
{
char buf[512];
int err = -1;
FILE *fp = fopen("/proc/net/dev", "r");
if (fp == NULL) {
perror("fopen");
return -1;
}
/* skip header lines */
if (!fgets(buf, sizeof(buf), fp) ||
!fgets(buf, sizeof(buf), fp)) {
fprintf(stderr, "/proc/net/dev read error\n");
goto end;
}
while (fgets(buf, sizeof(buf), fp) != NULL) {
char name[IFNAMSIZ];
int index, type;
struct ip_tunnel_parm p1 = {};
char *ptr;
buf[sizeof(buf) - 1] = 0;
ptr = strchr(buf, ':');
if (ptr == NULL ||
(*ptr++ = 0, sscanf(buf, "%s", name) != 1)) {
fprintf(stderr, "Wrong format for /proc/net/dev. Giving up.\n");
goto end;
}
if (p->name[0] && strcmp(p->name, name))
continue;
index = ll_name_to_index(name);
if (index == 0)
continue;
type = ll_index_to_type(index);
if (type == -1) {
fprintf(stderr, "Failed to get type of \"%s\"\n", name);
continue;
}
if (type != ARPHRD_TUNNEL && type != ARPHRD_IPGRE && type != ARPHRD_SIT)
continue;
if (tnl_get_ioctl(name, &p1))
continue;
if ((p->link && p1.link != p->link) ||
(p->name[0] && strcmp(p1.name, p->name)) ||
(p->iph.daddr && p1.iph.daddr != p->iph.daddr) ||
(p->iph.saddr && p1.iph.saddr != p->iph.saddr) ||
(p->i_key && p1.i_key != p->i_key))
continue;
print_tunnel(&p1);
if (show_stats)
tnl_print_stats(ptr);
printf("\n");
}
err = 0;
end:
fclose(fp);
return err;
}
static int do_show(int argc, char **argv)
{
struct ip_tunnel_parm p;
const char *basedev;
ll_init_map(&rth);
if (parse_args(argc, argv, SIOCGETTUNNEL, &p) < 0)
return -1;
basedev = tnl_defname(&p);
if (!basedev)
return do_tunnels_list(&p);
if (tnl_get_ioctl(p.name[0] ? p.name : basedev, &p))
return -1;
print_tunnel(&p);
printf("\n");
return 0;
}
static int do_prl(int argc, char **argv)
{
struct ip_tunnel_prl p = {};
int count = 0;
int cmd = 0;
const char *medium = NULL;
while (argc > 0) {
if (strcmp(*argv, "prl-default") == 0) {
NEXT_ARG();
cmd = SIOCADDPRL;
p.addr = get_addr32(*argv);
p.flags |= PRL_DEFAULT;
count++;
} else if (strcmp(*argv, "prl-nodefault") == 0) {
NEXT_ARG();
cmd = SIOCADDPRL;
p.addr = get_addr32(*argv);
count++;
} else if (strcmp(*argv, "prl-delete") == 0) {
NEXT_ARG();
cmd = SIOCDELPRL;
p.addr = get_addr32(*argv);
count++;
} else if (strcmp(*argv, "dev") == 0) {
NEXT_ARG();
if (check_ifname(*argv))
invarg("\"dev\" not a valid ifname", *argv);
medium = *argv;
} else {
fprintf(stderr,
"Invalid PRL parameter \"%s\"\n", *argv);
exit(-1);
}
if (count > 1) {
fprintf(stderr,
"One PRL entry at a time\n");
exit(-1);
}
argc--; argv++;
}
if (!medium) {
fprintf(stderr, "Must specify device\n");
exit(-1);
}
return tnl_prl_ioctl(cmd, medium, &p);
}
static int do_6rd(int argc, char **argv)
{
struct ip_tunnel_6rd ip6rd = {};
int cmd = 0;
const char *medium = NULL;
inet_prefix prefix;
while (argc > 0) {
if (strcmp(*argv, "6rd-prefix") == 0) {
NEXT_ARG();
if (get_prefix(&prefix, *argv, AF_INET6))
invarg("invalid 6rd_prefix\n", *argv);
cmd = SIOCADD6RD;
memcpy(&ip6rd.prefix, prefix.data, 16);
ip6rd.prefixlen = prefix.bitlen;
} else if (strcmp(*argv, "6rd-relay_prefix") == 0) {
NEXT_ARG();
if (get_prefix(&prefix, *argv, AF_INET))
invarg("invalid 6rd-relay_prefix\n", *argv);
cmd = SIOCADD6RD;
memcpy(&ip6rd.relay_prefix, prefix.data, 4);
ip6rd.relay_prefixlen = prefix.bitlen;
} else if (strcmp(*argv, "6rd-reset") == 0) {
cmd = SIOCDEL6RD;
} else if (strcmp(*argv, "dev") == 0) {
NEXT_ARG();
if (check_ifname(*argv))
invarg("\"dev\" not a valid ifname", *argv);
medium = *argv;
} else {
fprintf(stderr,
"Invalid 6RD parameter \"%s\"\n", *argv);
exit(-1);
}
argc--; argv++;
}
if (!medium) {
fprintf(stderr, "Must specify device\n");
exit(-1);
}
return tnl_6rd_ioctl(cmd, medium, &ip6rd);
}
static int tunnel_mode_is_ipv6(char *tunnel_mode)
{
static const char * const ipv6_modes[] = {
"ipv6/ipv6", "ip6ip6",
"vti6",
"ip/ipv6", "ipv4/ipv6", "ipip6", "ip4ip6",
"ip6gre", "gre/ipv6",
"any/ipv6", "any"
};
int i;
for (i = 0; i < ARRAY_SIZE(ipv6_modes); i++) {
if (strcmp(ipv6_modes[i], tunnel_mode) == 0)
return 1;
}
return 0;
}
int do_iptunnel(int argc, char **argv)
{
int i;
for (i = 0; i < argc - 1; i++) {
if (strcmp(argv[i], "mode") == 0) {
if (tunnel_mode_is_ipv6(argv[i + 1]))
preferred_family = AF_INET6;
break;
}
}
switch (preferred_family) {
case AF_UNSPEC:
preferred_family = AF_INET;
break;
case AF_INET:
break;
/*
* This is silly enough but we have no easy way to make it
* protocol-independent because of unarranged structure between
* IPv4 and IPv6.
*/
case AF_INET6:
return do_ip6tunnel(argc, argv);
default:
fprintf(stderr, "Unsupported protocol family: %d\n", preferred_family);
exit(-1);
}
if (argc > 0) {
if (matches(*argv, "add") == 0)
return do_add(SIOCADDTUNNEL, argc - 1, argv + 1);
if (matches(*argv, "change") == 0)
return do_add(SIOCCHGTUNNEL, argc - 1, argv + 1);
if (matches(*argv, "delete") == 0)
return do_del(argc - 1, argv + 1);
if (matches(*argv, "show") == 0 ||
matches(*argv, "lst") == 0 ||
matches(*argv, "list") == 0)
return do_show(argc - 1, argv + 1);
if (matches(*argv, "prl") == 0)
return do_prl(argc - 1, argv + 1);
if (matches(*argv, "6rd") == 0)
return do_6rd(argc - 1, argv + 1);
if (matches(*argv, "help") == 0)
usage();
} else
return do_show(0, NULL);
fprintf(stderr, "Command \"%s\" is unknown, try \"ip tunnel help\"\n", *argv);
exit(-1);
}
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