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mirror_iproute2/ip/link_gre.c
Philip Prindeville adbb296594 iproute2: add support for GRE ignore-df knob 
In the presence of firewalls which improperly block ICMP Unreachable
(including Fragmentation Required) messages, Path MTU Discovery is
prevented from working.

The workaround is to handle IPv4 payloads opaquely, ignoring the DF
bit.

Kernel commit 22a59be8b7693eb2d0897a9638f5991f2f8e4ddd ("net: ipv4:
Add ability to have GRE ignore DF bit in IPv4 payloads") is
complemented by this user-space changeset which exposes control of
this setting.

Reviewed-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>
2017-07-20 17:25:54 -07:00

541 lines
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/*
* link_gre.c gre driver module
*
* 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: Herbert Xu <herbert@gondor.apana.org.au>
*
*/
#include <string.h>
#include <net/if.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.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 print_usage(FILE *f)
{
fprintf(f,
"Usage: ... { gre | gretap } [ remote ADDR ]\n"
" [ local ADDR ]\n"
" [ [i|o]seq ]\n"
" [ [i|o]key KEY ]\n"
" [ [i|o]csum ]\n"
" [ ttl TTL ]\n"
" [ tos TOS ]\n"
" [ [no]pmtudisc ]\n"
" [ [no]ignore-df ]\n"
" [ dev PHYS_DEV ]\n"
" [ noencap ]\n"
" [ encap { fou | gue | none } ]\n"
" [ encap-sport PORT ]\n"
" [ encap-dport PORT ]\n"
" [ [no]encap-csum ]\n"
" [ [no]encap-csum6 ]\n"
" [ [no]encap-remcsum ]\n"
" [ fwmark MARK ]\n"
"\n"
"Where: ADDR := { IP_ADDRESS | any }\n"
" TOS := { NUMBER | inherit }\n"
" TTL := { 1..255 | inherit }\n"
" KEY := { DOTTED_QUAD | NUMBER }\n"
" MARK := { 0x0..0xffffffff }\n"
);
}
static void usage(void) __attribute__((noreturn));
static void usage(void)
{
print_usage(stderr);
exit(-1);
}
static int gre_parse_opt(struct link_util *lu, int argc, char **argv,
struct nlmsghdr *n)
{
struct ifinfomsg *ifi = (struct ifinfomsg *)(n + 1);
struct {
struct nlmsghdr n;
struct ifinfomsg i;
char buf[16384];
} req = {
.n.nlmsg_len = NLMSG_LENGTH(sizeof(*ifi)),
.n.nlmsg_flags = NLM_F_REQUEST,
.n.nlmsg_type = RTM_GETLINK,
.i.ifi_family = preferred_family,
.i.ifi_index = ifi->ifi_index,
};
struct rtattr *tb[IFLA_MAX + 1];
struct rtattr *linkinfo[IFLA_INFO_MAX+1];
struct rtattr *greinfo[IFLA_GRE_MAX + 1];
__u16 iflags = 0;
__u16 oflags = 0;
unsigned int ikey = 0;
unsigned int okey = 0;
unsigned int saddr = 0;
unsigned int daddr = 0;
unsigned int link = 0;
__u8 pmtudisc = 1;
__u8 ttl = 0;
__u8 tos = 0;
int len;
__u16 encaptype = 0;
__u16 encapflags = 0;
__u16 encapsport = 0;
__u16 encapdport = 0;
__u8 metadata = 0;
__u8 ignore_df = 0;
__u32 fwmark = 0;
if (!(n->nlmsg_flags & NLM_F_CREATE)) {
if (rtnl_talk(&rth, &req.n, &req.n, sizeof(req)) < 0) {
get_failed:
fprintf(stderr,
"Failed to get existing tunnel info.\n");
return -1;
}
len = req.n.nlmsg_len;
len -= NLMSG_LENGTH(sizeof(*ifi));
if (len < 0)
goto get_failed;
parse_rtattr(tb, IFLA_MAX, IFLA_RTA(&req.i), len);
if (!tb[IFLA_LINKINFO])
goto get_failed;
parse_rtattr_nested(linkinfo, IFLA_INFO_MAX, tb[IFLA_LINKINFO]);
if (!linkinfo[IFLA_INFO_DATA])
goto get_failed;
parse_rtattr_nested(greinfo, IFLA_GRE_MAX,
linkinfo[IFLA_INFO_DATA]);
if (greinfo[IFLA_GRE_IKEY])
ikey = rta_getattr_u32(greinfo[IFLA_GRE_IKEY]);
if (greinfo[IFLA_GRE_OKEY])
okey = rta_getattr_u32(greinfo[IFLA_GRE_OKEY]);
if (greinfo[IFLA_GRE_IFLAGS])
iflags = rta_getattr_u16(greinfo[IFLA_GRE_IFLAGS]);
if (greinfo[IFLA_GRE_OFLAGS])
oflags = rta_getattr_u16(greinfo[IFLA_GRE_OFLAGS]);
if (greinfo[IFLA_GRE_LOCAL])
saddr = rta_getattr_u32(greinfo[IFLA_GRE_LOCAL]);
if (greinfo[IFLA_GRE_REMOTE])
daddr = rta_getattr_u32(greinfo[IFLA_GRE_REMOTE]);
if (greinfo[IFLA_GRE_PMTUDISC])
pmtudisc = rta_getattr_u8(
greinfo[IFLA_GRE_PMTUDISC]);
if (greinfo[IFLA_GRE_TTL])
ttl = rta_getattr_u8(greinfo[IFLA_GRE_TTL]);
if (greinfo[IFLA_GRE_TOS])
tos = rta_getattr_u8(greinfo[IFLA_GRE_TOS]);
if (greinfo[IFLA_GRE_LINK])
link = rta_getattr_u8(greinfo[IFLA_GRE_LINK]);
if (greinfo[IFLA_GRE_ENCAP_TYPE])
encaptype = rta_getattr_u16(greinfo[IFLA_GRE_ENCAP_TYPE]);
if (greinfo[IFLA_GRE_ENCAP_FLAGS])
encapflags = rta_getattr_u16(greinfo[IFLA_GRE_ENCAP_FLAGS]);
if (greinfo[IFLA_GRE_ENCAP_SPORT])
encapsport = rta_getattr_u16(greinfo[IFLA_GRE_ENCAP_SPORT]);
if (greinfo[IFLA_GRE_ENCAP_DPORT])
encapdport = rta_getattr_u16(greinfo[IFLA_GRE_ENCAP_DPORT]);
if (greinfo[IFLA_GRE_COLLECT_METADATA])
metadata = 1;
if (greinfo[IFLA_GRE_IGNORE_DF])
ignore_df =
!!rta_getattr_u8(greinfo[IFLA_GRE_IGNORE_DF]);
if (greinfo[IFLA_GRE_FWMARK])
fwmark = rta_getattr_u32(greinfo[IFLA_GRE_FWMARK]);
}
while (argc > 0) {
if (!matches(*argv, "key")) {
unsigned int uval;
NEXT_ARG();
iflags |= GRE_KEY;
oflags |= GRE_KEY;
if (strchr(*argv, '.'))
uval = get_addr32(*argv);
else {
if (get_unsigned(&uval, *argv, 0) < 0) {
fprintf(stderr,
"Invalid value for \"key\": \"%s\"; it should be an unsigned integer\n", *argv);
exit(-1);
}
uval = htonl(uval);
}
ikey = okey = uval;
} else if (!matches(*argv, "ikey")) {
unsigned int uval;
NEXT_ARG();
iflags |= GRE_KEY;
if (strchr(*argv, '.'))
uval = get_addr32(*argv);
else {
if (get_unsigned(&uval, *argv, 0) < 0) {
fprintf(stderr, "invalid value for \"ikey\": \"%s\"; it should be an unsigned integer\n", *argv);
exit(-1);
}
uval = htonl(uval);
}
ikey = uval;
} else if (!matches(*argv, "okey")) {
unsigned int uval;
NEXT_ARG();
oflags |= GRE_KEY;
if (strchr(*argv, '.'))
uval = get_addr32(*argv);
else {
if (get_unsigned(&uval, *argv, 0) < 0) {
fprintf(stderr, "invalid value for \"okey\": \"%s\"; it should be an unsigned integer\n", *argv);
exit(-1);
}
uval = htonl(uval);
}
okey = uval;
} else if (!matches(*argv, "seq")) {
iflags |= GRE_SEQ;
oflags |= GRE_SEQ;
} else if (!matches(*argv, "iseq")) {
iflags |= GRE_SEQ;
} else if (!matches(*argv, "oseq")) {
oflags |= GRE_SEQ;
} else if (!matches(*argv, "csum")) {
iflags |= GRE_CSUM;
oflags |= GRE_CSUM;
} else if (!matches(*argv, "icsum")) {
iflags |= GRE_CSUM;
} else if (!matches(*argv, "ocsum")) {
oflags |= GRE_CSUM;
} else if (!matches(*argv, "nopmtudisc")) {
pmtudisc = 0;
} else if (!matches(*argv, "pmtudisc")) {
pmtudisc = 1;
} else if (!matches(*argv, "remote")) {
NEXT_ARG();
if (strcmp(*argv, "any"))
daddr = get_addr32(*argv);
} else if (!matches(*argv, "local")) {
NEXT_ARG();
if (strcmp(*argv, "any"))
saddr = get_addr32(*argv);
} else if (!matches(*argv, "dev")) {
NEXT_ARG();
link = if_nametoindex(*argv);
if (link == 0) {
fprintf(stderr, "Cannot find device \"%s\"\n",
*argv);
exit(-1);
}
} else if (!matches(*argv, "ttl") ||
!matches(*argv, "hoplimit")) {
unsigned int uval;
NEXT_ARG();
if (strcmp(*argv, "inherit") != 0) {
if (get_unsigned(&uval, *argv, 0))
invarg("invalid TTL\n", *argv);
if (uval > 255)
invarg("TTL must be <= 255\n", *argv);
ttl = uval;
}
} else if (!matches(*argv, "tos") ||
!matches(*argv, "tclass") ||
!matches(*argv, "dsfield")) {
__u32 uval;
NEXT_ARG();
if (strcmp(*argv, "inherit") != 0) {
if (rtnl_dsfield_a2n(&uval, *argv))
invarg("bad TOS value", *argv);
tos = uval;
} else
tos = 1;
} else if (strcmp(*argv, "noencap") == 0) {
encaptype = TUNNEL_ENCAP_NONE;
} else if (strcmp(*argv, "encap") == 0) {
NEXT_ARG();
if (strcmp(*argv, "fou") == 0)
encaptype = TUNNEL_ENCAP_FOU;
else if (strcmp(*argv, "gue") == 0)
encaptype = TUNNEL_ENCAP_GUE;
else if (strcmp(*argv, "none") == 0)
encaptype = TUNNEL_ENCAP_NONE;
else
invarg("Invalid encap type.", *argv);
} else if (strcmp(*argv, "encap-sport") == 0) {
NEXT_ARG();
if (strcmp(*argv, "auto") == 0)
encapsport = 0;
else if (get_u16(&encapsport, *argv, 0))
invarg("Invalid source port.", *argv);
} else if (strcmp(*argv, "encap-dport") == 0) {
NEXT_ARG();
if (get_u16(&encapdport, *argv, 0))
invarg("Invalid destination port.", *argv);
} else if (strcmp(*argv, "encap-csum") == 0) {
encapflags |= TUNNEL_ENCAP_FLAG_CSUM;
} else if (strcmp(*argv, "noencap-csum") == 0) {
encapflags &= ~TUNNEL_ENCAP_FLAG_CSUM;
} else if (strcmp(*argv, "encap-udp6-csum") == 0) {
encapflags |= TUNNEL_ENCAP_FLAG_CSUM6;
} else if (strcmp(*argv, "noencap-udp6-csum") == 0) {
encapflags |= ~TUNNEL_ENCAP_FLAG_CSUM6;
} else if (strcmp(*argv, "encap-remcsum") == 0) {
encapflags |= TUNNEL_ENCAP_FLAG_REMCSUM;
} else if (strcmp(*argv, "noencap-remcsum") == 0) {
encapflags |= ~TUNNEL_ENCAP_FLAG_REMCSUM;
} else if (strcmp(*argv, "external") == 0) {
metadata = 1;
} else if (strcmp(*argv, "ignore-df") == 0) {
ignore_df = 1;
} else if (strcmp(*argv, "noignore-df") == 0) {
/*
*only the lsb is significant, use 2 for presence
*/
ignore_df = 2;
} else if (strcmp(*argv, "fwmark") == 0) {
NEXT_ARG();
if (get_u32(&fwmark, *argv, 0))
invarg("invalid fwmark\n", *argv);
} else
usage();
argc--; argv++;
}
if (!ikey && IN_MULTICAST(ntohl(daddr))) {
ikey = daddr;
iflags |= GRE_KEY;
}
if (!okey && IN_MULTICAST(ntohl(daddr))) {
okey = daddr;
oflags |= GRE_KEY;
}
if (IN_MULTICAST(ntohl(daddr)) && !saddr) {
fprintf(stderr, "A broadcast tunnel requires a source address.\n");
return -1;
}
if (!metadata) {
addattr32(n, 1024, IFLA_GRE_IKEY, ikey);
addattr32(n, 1024, IFLA_GRE_OKEY, okey);
addattr_l(n, 1024, IFLA_GRE_IFLAGS, &iflags, 2);
addattr_l(n, 1024, IFLA_GRE_OFLAGS, &oflags, 2);
addattr_l(n, 1024, IFLA_GRE_LOCAL, &saddr, 4);
addattr_l(n, 1024, IFLA_GRE_REMOTE, &daddr, 4);
addattr_l(n, 1024, IFLA_GRE_PMTUDISC, &pmtudisc, 1);
if (link)
addattr32(n, 1024, IFLA_GRE_LINK, link);
addattr_l(n, 1024, IFLA_GRE_TTL, &ttl, 1);
addattr_l(n, 1024, IFLA_GRE_TOS, &tos, 1);
addattr32(n, 1024, IFLA_GRE_FWMARK, fwmark);
} else {
addattr_l(n, 1024, IFLA_GRE_COLLECT_METADATA, NULL, 0);
}
addattr16(n, 1024, IFLA_GRE_ENCAP_TYPE, encaptype);
addattr16(n, 1024, IFLA_GRE_ENCAP_FLAGS, encapflags);
addattr16(n, 1024, IFLA_GRE_ENCAP_SPORT, htons(encapsport));
addattr16(n, 1024, IFLA_GRE_ENCAP_DPORT, htons(encapdport));
if (ignore_df)
addattr8(n, 1024, IFLA_GRE_IGNORE_DF, ignore_df & 1);
return 0;
}
static void gre_print_direct_opt(FILE *f, struct rtattr *tb[])
{
char s2[64];
const char *local = "any";
const char *remote = "any";
unsigned int iflags = 0;
unsigned int oflags = 0;
if (tb[IFLA_GRE_REMOTE]) {
unsigned int addr = rta_getattr_u32(tb[IFLA_GRE_REMOTE]);
if (addr)
remote = format_host(AF_INET, 4, &addr);
}
fprintf(f, "remote %s ", remote);
if (tb[IFLA_GRE_LOCAL]) {
unsigned int addr = rta_getattr_u32(tb[IFLA_GRE_LOCAL]);
if (addr)
local = format_host(AF_INET, 4, &addr);
}
fprintf(f, "local %s ", local);
if (tb[IFLA_GRE_LINK] && rta_getattr_u32(tb[IFLA_GRE_LINK])) {
unsigned int link = rta_getattr_u32(tb[IFLA_GRE_LINK]);
const char *n = if_indextoname(link, s2);
if (n)
fprintf(f, "dev %s ", n);
else
fprintf(f, "dev %u ", link);
}
if (tb[IFLA_GRE_TTL] && rta_getattr_u8(tb[IFLA_GRE_TTL]))
fprintf(f, "ttl %d ", rta_getattr_u8(tb[IFLA_GRE_TTL]));
else
fprintf(f, "ttl inherit ");
if (tb[IFLA_GRE_TOS] && rta_getattr_u8(tb[IFLA_GRE_TOS])) {
int tos = rta_getattr_u8(tb[IFLA_GRE_TOS]);
fputs("tos ", f);
if (tos == 1)
fputs("inherit ", f);
else
fprintf(f, "0x%x ", tos);
}
if (tb[IFLA_GRE_PMTUDISC] &&
!rta_getattr_u8(tb[IFLA_GRE_PMTUDISC]))
fputs("nopmtudisc ", f);
if (tb[IFLA_GRE_IFLAGS])
iflags = rta_getattr_u16(tb[IFLA_GRE_IFLAGS]);
if (tb[IFLA_GRE_OFLAGS])
oflags = rta_getattr_u16(tb[IFLA_GRE_OFLAGS]);
if ((iflags & GRE_KEY) && tb[IFLA_GRE_IKEY]) {
inet_ntop(AF_INET, RTA_DATA(tb[IFLA_GRE_IKEY]), s2, sizeof(s2));
fprintf(f, "ikey %s ", s2);
}
if ((oflags & GRE_KEY) && tb[IFLA_GRE_OKEY]) {
inet_ntop(AF_INET, RTA_DATA(tb[IFLA_GRE_OKEY]), s2, sizeof(s2));
fprintf(f, "okey %s ", s2);
}
if (iflags & GRE_SEQ)
fputs("iseq ", f);
if (oflags & GRE_SEQ)
fputs("oseq ", f);
if (iflags & GRE_CSUM)
fputs("icsum ", f);
if (oflags & GRE_CSUM)
fputs("ocsum ", f);
if (tb[IFLA_GRE_FWMARK] && rta_getattr_u32(tb[IFLA_GRE_FWMARK])) {
fprintf(f, "fwmark 0x%x ",
rta_getattr_u32(tb[IFLA_GRE_FWMARK]));
}
}
static void gre_print_opt(struct link_util *lu, FILE *f, struct rtattr *tb[])
{
if (!tb)
return;
if (!tb[IFLA_GRE_COLLECT_METADATA])
gre_print_direct_opt(f, tb);
else
fputs("external ", f);
if (tb[IFLA_GRE_IGNORE_DF] && rta_getattr_u8(tb[IFLA_GRE_IGNORE_DF]))
fputs("ignore-df ", f);
if (tb[IFLA_GRE_ENCAP_TYPE] &&
rta_getattr_u16(tb[IFLA_GRE_ENCAP_TYPE]) != TUNNEL_ENCAP_NONE) {
__u16 type = rta_getattr_u16(tb[IFLA_GRE_ENCAP_TYPE]);
__u16 flags = rta_getattr_u16(tb[IFLA_GRE_ENCAP_FLAGS]);
__u16 sport = rta_getattr_u16(tb[IFLA_GRE_ENCAP_SPORT]);
__u16 dport = rta_getattr_u16(tb[IFLA_GRE_ENCAP_DPORT]);
fputs("encap ", f);
switch (type) {
case TUNNEL_ENCAP_FOU:
fputs("fou ", f);
break;
case TUNNEL_ENCAP_GUE:
fputs("gue ", f);
break;
default:
fputs("unknown ", f);
break;
}
if (sport == 0)
fputs("encap-sport auto ", f);
else
fprintf(f, "encap-sport %u", ntohs(sport));
fprintf(f, "encap-dport %u ", ntohs(dport));
if (flags & TUNNEL_ENCAP_FLAG_CSUM)
fputs("encap-csum ", f);
else
fputs("noencap-csum ", f);
if (flags & TUNNEL_ENCAP_FLAG_CSUM6)
fputs("encap-csum6 ", f);
else
fputs("noencap-csum6 ", f);
if (flags & TUNNEL_ENCAP_FLAG_REMCSUM)
fputs("encap-remcsum ", f);
else
fputs("noencap-remcsum ", f);
}
}
static void gre_print_help(struct link_util *lu, int argc, char **argv,
FILE *f)
{
print_usage(f);
}
struct link_util gre_link_util = {
.id = "gre",
.maxattr = IFLA_GRE_MAX,
.parse_opt = gre_parse_opt,
.print_opt = gre_print_opt,
.print_help = gre_print_help,
};
struct link_util gretap_link_util = {
.id = "gretap",
.maxattr = IFLA_GRE_MAX,
.parse_opt = gre_parse_opt,
.print_opt = gre_print_opt,
.print_help = gre_print_help,
};
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