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linux/net/ipv6/exthdrs.c
Menglong Dong 7d9dbdfbfd net: ipv6: add skb drop reasons to TLV parse 
Replace kfree_skb() used in TLV encoded option header parsing with
kfree_skb_reason(). Following functions are involved:

ip6_parse_tlv()
ipv6_hop_ra()
ipv6_hop_ioam()
ipv6_hop_jumbo()
ipv6_hop_calipso()
ipv6_dest_hao()

Most skb drops during this process are regarded as 'InHdrErrors',
as 'IPSTATS_MIB_INHDRERRORS' is used when ip6_parse_tlv() fails,
which make we use 'SKB_DROP_REASON_IP_INHDR' correspondingly.

However, 'IP_INHDR' is a relatively general reason. Therefore, we
can use other reasons with higher priority in some cases. For example,
'SKB_DROP_REASON_UNHANDLED_PROTO' is used for unknown TLV options.

Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-04-13 13:09:57 +01:00

1409 lines
33 KiB
C
Raw Blame History

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Extension Header handling for IPv6
* Linux INET6 implementation
*
* Authors:
* Pedro Roque <roque@di.fc.ul.pt>
* Andi Kleen <ak@muc.de>
* Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
*/
/* Changes:
* yoshfuji : ensure not to overrun while parsing
* tlv options.
* Mitsuru KANDA @USAGI and: Remove ipv6_parse_exthdrs().
* YOSHIFUJI Hideaki @USAGI Register inbound extension header
* handlers as inet6_protocol{}.
*/
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/in6.h>
#include <linux/icmpv6.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <net/dst.h>
#include <net/sock.h>
#include <net/snmp.h>
#include <net/ipv6.h>
#include <net/protocol.h>
#include <net/transp_v6.h>
#include <net/rawv6.h>
#include <net/ndisc.h>
#include <net/ip6_route.h>
#include <net/addrconf.h>
#include <net/calipso.h>
#if IS_ENABLED(CONFIG_IPV6_MIP6)
#include <net/xfrm.h>
#endif
#include <linux/seg6.h>
#include <net/seg6.h>
#ifdef CONFIG_IPV6_SEG6_HMAC
#include <net/seg6_hmac.h>
#endif
#include <net/rpl.h>
#include <linux/ioam6.h>
#include <net/ioam6.h>
#include <net/dst_metadata.h>
#include <linux/uaccess.h>
/*********************
Generic functions
*********************/
/* An unknown option is detected, decide what to do */
static bool ip6_tlvopt_unknown(struct sk_buff *skb, int optoff,
bool disallow_unknowns)
{
if (disallow_unknowns) {
/* If unknown TLVs are disallowed by configuration
* then always silently drop packet. Note this also
* means no ICMP parameter problem is sent which
* could be a good property to mitigate a reflection DOS
* attack.
*/
goto drop;
}
switch ((skb_network_header(skb)[optoff] & 0xC0) >> 6) {
case 0: /* ignore */
return true;
case 1: /* drop packet */
break;
case 3: /* Send ICMP if not a multicast address and drop packet */
/* Actually, it is redundant check. icmp_send
will recheck in any case.
*/
if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr))
break;
fallthrough;
case 2: /* send ICMP PARM PROB regardless and drop packet */
icmpv6_param_prob_reason(skb, ICMPV6_UNK_OPTION, optoff,
SKB_DROP_REASON_UNHANDLED_PROTO);
return false;
}
drop:
kfree_skb_reason(skb, SKB_DROP_REASON_UNHANDLED_PROTO);
return false;
}
static bool ipv6_hop_ra(struct sk_buff *skb, int optoff);
static bool ipv6_hop_ioam(struct sk_buff *skb, int optoff);
static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff);
static bool ipv6_hop_calipso(struct sk_buff *skb, int optoff);
#if IS_ENABLED(CONFIG_IPV6_MIP6)
static bool ipv6_dest_hao(struct sk_buff *skb, int optoff);
#endif
/* Parse tlv encoded option header (hop-by-hop or destination) */
static bool ip6_parse_tlv(bool hopbyhop,
struct sk_buff *skb,
int max_count)
{
int len = (skb_transport_header(skb)[1] + 1) << 3;
const unsigned char *nh = skb_network_header(skb);
int off = skb_network_header_len(skb);
bool disallow_unknowns = false;
int tlv_count = 0;
int padlen = 0;
if (unlikely(max_count < 0)) {
disallow_unknowns = true;
max_count = -max_count;
}
if (skb_transport_offset(skb) + len > skb_headlen(skb))
goto bad;
off += 2;
len -= 2;
while (len > 0) {
int optlen, i;
if (nh[off] == IPV6_TLV_PAD1) {
padlen++;
if (padlen > 7)
goto bad;
off++;
len--;
continue;
}
if (len < 2)
goto bad;
optlen = nh[off + 1] + 2;
if (optlen > len)
goto bad;
if (nh[off] == IPV6_TLV_PADN) {
/* RFC 2460 states that the purpose of PadN is
* to align the containing header to multiples
* of 8. 7 is therefore the highest valid value.
* See also RFC 4942, Section 2.1.9.5.
*/
padlen += optlen;
if (padlen > 7)
goto bad;
/* RFC 4942 recommends receiving hosts to
* actively check PadN payload to contain
* only zeroes.
*/
for (i = 2; i < optlen; i++) {
if (nh[off + i] != 0)
goto bad;
}
} else {
tlv_count++;
if (tlv_count > max_count)
goto bad;
if (hopbyhop) {
switch (nh[off]) {
case IPV6_TLV_ROUTERALERT:
if (!ipv6_hop_ra(skb, off))
return false;
break;
case IPV6_TLV_IOAM:
if (!ipv6_hop_ioam(skb, off))
return false;
break;
case IPV6_TLV_JUMBO:
if (!ipv6_hop_jumbo(skb, off))
return false;
break;
case IPV6_TLV_CALIPSO:
if (!ipv6_hop_calipso(skb, off))
return false;
break;
default:
if (!ip6_tlvopt_unknown(skb, off,
disallow_unknowns))
return false;
break;
}
} else {
switch (nh[off]) {
#if IS_ENABLED(CONFIG_IPV6_MIP6)
case IPV6_TLV_HAO:
if (!ipv6_dest_hao(skb, off))
return false;
break;
#endif
default:
if (!ip6_tlvopt_unknown(skb, off,
disallow_unknowns))
return false;
break;
}
}
padlen = 0;
}
off += optlen;
len -= optlen;
}
if (len == 0)
return true;
bad:
kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR);
return false;
}
/*****************************
Destination options header.
*****************************/
#if IS_ENABLED(CONFIG_IPV6_MIP6)
static bool ipv6_dest_hao(struct sk_buff *skb, int optoff)
{
struct ipv6_destopt_hao *hao;
struct inet6_skb_parm *opt = IP6CB(skb);
struct ipv6hdr *ipv6h = ipv6_hdr(skb);
SKB_DR(reason);
int ret;
if (opt->dsthao) {
net_dbg_ratelimited("hao duplicated\n");
goto discard;
}
opt->dsthao = opt->dst1;
opt->dst1 = 0;
hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) + optoff);
if (hao->length != 16) {
net_dbg_ratelimited("hao invalid option length = %d\n",
hao->length);
SKB_DR_SET(reason, IP_INHDR);
goto discard;
}
if (!(ipv6_addr_type(&hao->addr) & IPV6_ADDR_UNICAST)) {
net_dbg_ratelimited("hao is not an unicast addr: %pI6\n",
&hao->addr);
SKB_DR_SET(reason, INVALID_PROTO);
goto discard;
}
ret = xfrm6_input_addr(skb, (xfrm_address_t *)&ipv6h->daddr,
(xfrm_address_t *)&hao->addr, IPPROTO_DSTOPTS);
if (unlikely(ret < 0)) {
SKB_DR_SET(reason, XFRM_POLICY);
goto discard;
}
if (skb_cloned(skb)) {
if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
goto discard;
/* update all variable using below by copied skbuff */
hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) +
optoff);
ipv6h = ipv6_hdr(skb);
}
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->ip_summed = CHECKSUM_NONE;
swap(ipv6h->saddr, hao->addr);
if (skb->tstamp == 0)
__net_timestamp(skb);
return true;
discard:
kfree_skb_reason(skb, reason);
return false;
}
#endif
static int ipv6_destopt_rcv(struct sk_buff *skb)
{
struct inet6_dev *idev = __in6_dev_get(skb->dev);
struct inet6_skb_parm *opt = IP6CB(skb);
#if IS_ENABLED(CONFIG_IPV6_MIP6)
__u16 dstbuf;
#endif
struct dst_entry *dst = skb_dst(skb);
struct net *net = dev_net(skb->dev);
int extlen;
if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
!pskb_may_pull(skb, (skb_transport_offset(skb) +
((skb_transport_header(skb)[1] + 1) << 3)))) {
__IP6_INC_STATS(dev_net(dst->dev), idev,
IPSTATS_MIB_INHDRERRORS);
fail_and_free:
kfree_skb(skb);
return -1;
}
extlen = (skb_transport_header(skb)[1] + 1) << 3;
if (extlen > net->ipv6.sysctl.max_dst_opts_len)
goto fail_and_free;
opt->lastopt = opt->dst1 = skb_network_header_len(skb);
#if IS_ENABLED(CONFIG_IPV6_MIP6)
dstbuf = opt->dst1;
#endif
if (ip6_parse_tlv(false, skb, net->ipv6.sysctl.max_dst_opts_cnt)) {
skb->transport_header += extlen;
opt = IP6CB(skb);
#if IS_ENABLED(CONFIG_IPV6_MIP6)
opt->nhoff = dstbuf;
#else
opt->nhoff = opt->dst1;
#endif
return 1;
}
__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
return -1;
}
static void seg6_update_csum(struct sk_buff *skb)
{
struct ipv6_sr_hdr *hdr;
struct in6_addr *addr;
__be32 from, to;
/* srh is at transport offset and seg_left is already decremented
* but daddr is not yet updated with next segment
*/
hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
addr = hdr->segments + hdr->segments_left;
hdr->segments_left++;
from = *(__be32 *)hdr;
hdr->segments_left--;
to = *(__be32 *)hdr;
/* update skb csum with diff resulting from seg_left decrement */
update_csum_diff4(skb, from, to);
/* compute csum diff between current and next segment and update */
update_csum_diff16(skb, (__be32 *)(&ipv6_hdr(skb)->daddr),
(__be32 *)addr);
}
static int ipv6_srh_rcv(struct sk_buff *skb)
{
struct inet6_skb_parm *opt = IP6CB(skb);
struct net *net = dev_net(skb->dev);
struct ipv6_sr_hdr *hdr;
struct inet6_dev *idev;
struct in6_addr *addr;
int accept_seg6;
hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
idev = __in6_dev_get(skb->dev);
accept_seg6 = net->ipv6.devconf_all->seg6_enabled;
if (accept_seg6 > idev->cnf.seg6_enabled)
accept_seg6 = idev->cnf.seg6_enabled;
if (!accept_seg6) {
kfree_skb(skb);
return -1;
}
#ifdef CONFIG_IPV6_SEG6_HMAC
if (!seg6_hmac_validate_skb(skb)) {
kfree_skb(skb);
return -1;
}
#endif
looped_back:
if (hdr->segments_left == 0) {
if (hdr->nexthdr == NEXTHDR_IPV6 || hdr->nexthdr == NEXTHDR_IPV4) {
int offset = (hdr->hdrlen + 1) << 3;
skb_postpull_rcsum(skb, skb_network_header(skb),
skb_network_header_len(skb));
if (!pskb_pull(skb, offset)) {
kfree_skb(skb);
return -1;
}
skb_postpull_rcsum(skb, skb_transport_header(skb),
offset);
skb_reset_network_header(skb);
skb_reset_transport_header(skb);
skb->encapsulation = 0;
if (hdr->nexthdr == NEXTHDR_IPV4)
skb->protocol = htons(ETH_P_IP);
__skb_tunnel_rx(skb, skb->dev, net);
netif_rx(skb);
return -1;
}
opt->srcrt = skb_network_header_len(skb);
opt->lastopt = opt->srcrt;
skb->transport_header += (hdr->hdrlen + 1) << 3;
opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
return 1;
}
if (hdr->segments_left >= (hdr->hdrlen >> 1)) {
__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
((&hdr->segments_left) -
skb_network_header(skb)));
return -1;
}
if (skb_cloned(skb)) {
if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
IPSTATS_MIB_OUTDISCARDS);
kfree_skb(skb);
return -1;
}
}
hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
hdr->segments_left--;
addr = hdr->segments + hdr->segments_left;
skb_push(skb, sizeof(struct ipv6hdr));
if (skb->ip_summed == CHECKSUM_COMPLETE)
seg6_update_csum(skb);
ipv6_hdr(skb)->daddr = *addr;
skb_dst_drop(skb);
ip6_route_input(skb);
if (skb_dst(skb)->error) {
dst_input(skb);
return -1;
}
if (skb_dst(skb)->dev->flags & IFF_LOOPBACK) {
if (ipv6_hdr(skb)->hop_limit <= 1) {
__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
icmpv6_send(skb, ICMPV6_TIME_EXCEED,
ICMPV6_EXC_HOPLIMIT, 0);
kfree_skb(skb);
return -1;
}
ipv6_hdr(skb)->hop_limit--;
skb_pull(skb, sizeof(struct ipv6hdr));
goto looped_back;
}
dst_input(skb);
return -1;
}
static int ipv6_rpl_srh_rcv(struct sk_buff *skb)
{
struct ipv6_rpl_sr_hdr *hdr, *ohdr, *chdr;
struct inet6_skb_parm *opt = IP6CB(skb);
struct net *net = dev_net(skb->dev);
struct inet6_dev *idev;
struct ipv6hdr *oldhdr;
unsigned char *buf;
int accept_rpl_seg;
int i, err;
u64 n = 0;
u32 r;
idev = __in6_dev_get(skb->dev);
accept_rpl_seg = net->ipv6.devconf_all->rpl_seg_enabled;
if (accept_rpl_seg > idev->cnf.rpl_seg_enabled)
accept_rpl_seg = idev->cnf.rpl_seg_enabled;
if (!accept_rpl_seg) {
kfree_skb(skb);
return -1;
}
looped_back:
hdr = (struct ipv6_rpl_sr_hdr *)skb_transport_header(skb);
if (hdr->segments_left == 0) {
if (hdr->nexthdr == NEXTHDR_IPV6) {
int offset = (hdr->hdrlen + 1) << 3;
skb_postpull_rcsum(skb, skb_network_header(skb),
skb_network_header_len(skb));
if (!pskb_pull(skb, offset)) {
kfree_skb(skb);
return -1;
}
skb_postpull_rcsum(skb, skb_transport_header(skb),
offset);
skb_reset_network_header(skb);
skb_reset_transport_header(skb);
skb->encapsulation = 0;
__skb_tunnel_rx(skb, skb->dev, net);
netif_rx(skb);
return -1;
}
opt->srcrt = skb_network_header_len(skb);
opt->lastopt = opt->srcrt;
skb->transport_header += (hdr->hdrlen + 1) << 3;
opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
return 1;
}
if (!pskb_may_pull(skb, sizeof(*hdr))) {
kfree_skb(skb);
return -1;
}
n = (hdr->hdrlen << 3) - hdr->pad - (16 - hdr->cmpre);
r = do_div(n, (16 - hdr->cmpri));
/* checks if calculation was without remainder and n fits into
* unsigned char which is segments_left field. Should not be
* higher than that.
*/
if (r || (n + 1) > 255) {
kfree_skb(skb);
return -1;
}
if (hdr->segments_left > n + 1) {
__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
((&hdr->segments_left) -
skb_network_header(skb)));
return -1;
}
if (skb_cloned(skb)) {
if (pskb_expand_head(skb, IPV6_RPL_SRH_WORST_SWAP_SIZE, 0,
GFP_ATOMIC)) {
__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
IPSTATS_MIB_OUTDISCARDS);
kfree_skb(skb);
return -1;
}
} else {
err = skb_cow_head(skb, IPV6_RPL_SRH_WORST_SWAP_SIZE);
if (unlikely(err)) {
kfree_skb(skb);
return -1;
}
}
hdr = (struct ipv6_rpl_sr_hdr *)skb_transport_header(skb);
if (!pskb_may_pull(skb, ipv6_rpl_srh_size(n, hdr->cmpri,
hdr->cmpre))) {
kfree_skb(skb);
return -1;
}
hdr->segments_left--;
i = n - hdr->segments_left;
buf = kcalloc(struct_size(hdr, segments.addr, n + 2), 2, GFP_ATOMIC);
if (unlikely(!buf)) {
kfree_skb(skb);
return -1;
}
ohdr = (struct ipv6_rpl_sr_hdr *)buf;
ipv6_rpl_srh_decompress(ohdr, hdr, &ipv6_hdr(skb)->daddr, n);
chdr = (struct ipv6_rpl_sr_hdr *)(buf + ((ohdr->hdrlen + 1) << 3));
if ((ipv6_addr_type(&ipv6_hdr(skb)->daddr) & IPV6_ADDR_MULTICAST) ||
(ipv6_addr_type(&ohdr->rpl_segaddr[i]) & IPV6_ADDR_MULTICAST)) {
kfree_skb(skb);
kfree(buf);
return -1;
}
err = ipv6_chk_rpl_srh_loop(net, ohdr->rpl_segaddr, n + 1);
if (err) {
icmpv6_send(skb, ICMPV6_PARAMPROB, 0, 0);
kfree_skb(skb);
kfree(buf);
return -1;
}
swap(ipv6_hdr(skb)->daddr, ohdr->rpl_segaddr[i]);
ipv6_rpl_srh_compress(chdr, ohdr, &ipv6_hdr(skb)->daddr, n);
oldhdr = ipv6_hdr(skb);
skb_pull(skb, ((hdr->hdrlen + 1) << 3));
skb_postpull_rcsum(skb, oldhdr,
sizeof(struct ipv6hdr) + ((hdr->hdrlen + 1) << 3));
skb_push(skb, ((chdr->hdrlen + 1) << 3) + sizeof(struct ipv6hdr));
skb_reset_network_header(skb);
skb_mac_header_rebuild(skb);
skb_set_transport_header(skb, sizeof(struct ipv6hdr));
memmove(ipv6_hdr(skb), oldhdr, sizeof(struct ipv6hdr));
memcpy(skb_transport_header(skb), chdr, (chdr->hdrlen + 1) << 3);
ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
skb_postpush_rcsum(skb, ipv6_hdr(skb),
sizeof(struct ipv6hdr) + ((chdr->hdrlen + 1) << 3));
kfree(buf);
skb_dst_drop(skb);
ip6_route_input(skb);
if (skb_dst(skb)->error) {
dst_input(skb);
return -1;
}
if (skb_dst(skb)->dev->flags & IFF_LOOPBACK) {
if (ipv6_hdr(skb)->hop_limit <= 1) {
__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
icmpv6_send(skb, ICMPV6_TIME_EXCEED,
ICMPV6_EXC_HOPLIMIT, 0);
kfree_skb(skb);
return -1;
}
ipv6_hdr(skb)->hop_limit--;
skb_pull(skb, sizeof(struct ipv6hdr));
goto looped_back;
}
dst_input(skb);
return -1;
}
/********************************
Routing header.
********************************/
/* called with rcu_read_lock() */
static int ipv6_rthdr_rcv(struct sk_buff *skb)
{
struct inet6_dev *idev = __in6_dev_get(skb->dev);
struct inet6_skb_parm *opt = IP6CB(skb);
struct in6_addr *addr = NULL;
struct in6_addr daddr;
int n, i;
struct ipv6_rt_hdr *hdr;
struct rt0_hdr *rthdr;
struct net *net = dev_net(skb->dev);
int accept_source_route = net->ipv6.devconf_all->accept_source_route;
if (idev && accept_source_route > idev->cnf.accept_source_route)
accept_source_route = idev->cnf.accept_source_route;
if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
!pskb_may_pull(skb, (skb_transport_offset(skb) +
((skb_transport_header(skb)[1] + 1) << 3)))) {
__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
kfree_skb(skb);
return -1;
}
hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) ||
skb->pkt_type != PACKET_HOST) {
__IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
kfree_skb(skb);
return -1;
}
switch (hdr->type) {
case IPV6_SRCRT_TYPE_4:
/* segment routing */
return ipv6_srh_rcv(skb);
case IPV6_SRCRT_TYPE_3:
/* rpl segment routing */
return ipv6_rpl_srh_rcv(skb);
default:
break;
}
looped_back:
if (hdr->segments_left == 0) {
switch (hdr->type) {
#if IS_ENABLED(CONFIG_IPV6_MIP6)
case IPV6_SRCRT_TYPE_2:
/* Silently discard type 2 header unless it was
* processed by own
*/
if (!addr) {
__IP6_INC_STATS(net, idev,
IPSTATS_MIB_INADDRERRORS);
kfree_skb(skb);
return -1;
}
break;
#endif
default:
break;
}
opt->lastopt = opt->srcrt = skb_network_header_len(skb);
skb->transport_header += (hdr->hdrlen + 1) << 3;
opt->dst0 = opt->dst1;
opt->dst1 = 0;
opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
return 1;
}
switch (hdr->type) {
#if IS_ENABLED(CONFIG_IPV6_MIP6)
case IPV6_SRCRT_TYPE_2:
if (accept_source_route < 0)
goto unknown_rh;
/* Silently discard invalid RTH type 2 */
if (hdr->hdrlen != 2 || hdr->segments_left != 1) {
__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
kfree_skb(skb);
return -1;
}
break;
#endif
default:
goto unknown_rh;
}
/*
* This is the routing header forwarding algorithm from
* RFC 2460, page 16.
*/
n = hdr->hdrlen >> 1;
if (hdr->segments_left > n) {
__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
((&hdr->segments_left) -
skb_network_header(skb)));
return -1;
}
/* We are about to mangle packet header. Be careful!
Do not damage packets queued somewhere.
*/
if (skb_cloned(skb)) {
/* the copy is a forwarded packet */
if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
IPSTATS_MIB_OUTDISCARDS);
kfree_skb(skb);
return -1;
}
hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
}
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->ip_summed = CHECKSUM_NONE;
i = n - --hdr->segments_left;
rthdr = (struct rt0_hdr *) hdr;
addr = rthdr->addr;
addr += i - 1;
switch (hdr->type) {
#if IS_ENABLED(CONFIG_IPV6_MIP6)
case IPV6_SRCRT_TYPE_2:
if (xfrm6_input_addr(skb, (xfrm_address_t *)addr,
(xfrm_address_t *)&ipv6_hdr(skb)->saddr,
IPPROTO_ROUTING) < 0) {
__IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
kfree_skb(skb);
return -1;
}
if (!ipv6_chk_home_addr(dev_net(skb_dst(skb)->dev), addr)) {
__IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
kfree_skb(skb);
return -1;
}
break;
#endif
default:
break;
}
if (ipv6_addr_is_multicast(addr)) {
__IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
kfree_skb(skb);
return -1;
}
daddr = *addr;
*addr = ipv6_hdr(skb)->daddr;
ipv6_hdr(skb)->daddr = daddr;
skb_dst_drop(skb);
ip6_route_input(skb);
if (skb_dst(skb)->error) {
skb_push(skb, skb->data - skb_network_header(skb));
dst_input(skb);
return -1;
}
if (skb_dst(skb)->dev->flags&IFF_LOOPBACK) {
if (ipv6_hdr(skb)->hop_limit <= 1) {
__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
0);
kfree_skb(skb);
return -1;
}
ipv6_hdr(skb)->hop_limit--;
goto looped_back;
}
skb_push(skb, skb->data - skb_network_header(skb));
dst_input(skb);
return -1;
unknown_rh:
__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
(&hdr->type) - skb_network_header(skb));
return -1;
}
static const struct inet6_protocol rthdr_protocol = {
.handler = ipv6_rthdr_rcv,
.flags = INET6_PROTO_NOPOLICY,
};
static const struct inet6_protocol destopt_protocol = {
.handler = ipv6_destopt_rcv,
.flags = INET6_PROTO_NOPOLICY,
};
static const struct inet6_protocol nodata_protocol = {
.handler = dst_discard,
.flags = INET6_PROTO_NOPOLICY,
};
int __init ipv6_exthdrs_init(void)
{
int ret;
ret = inet6_add_protocol(&rthdr_protocol, IPPROTO_ROUTING);
if (ret)
goto out;
ret = inet6_add_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
if (ret)
goto out_rthdr;
ret = inet6_add_protocol(&nodata_protocol, IPPROTO_NONE);
if (ret)
goto out_destopt;
out:
return ret;
out_destopt:
inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
out_rthdr:
inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
goto out;
};
void ipv6_exthdrs_exit(void)
{
inet6_del_protocol(&nodata_protocol, IPPROTO_NONE);
inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
}
/**********************************
Hop-by-hop options.
**********************************/
/*
* Note: we cannot rely on skb_dst(skb) before we assign it in ip6_route_input().
*/
static inline struct net *ipv6_skb_net(struct sk_buff *skb)
{
return skb_dst(skb) ? dev_net(skb_dst(skb)->dev) : dev_net(skb->dev);
}
/* Router Alert as of RFC 2711 */
static bool ipv6_hop_ra(struct sk_buff *skb, int optoff)
{
const unsigned char *nh = skb_network_header(skb);
if (nh[optoff + 1] == 2) {
IP6CB(skb)->flags |= IP6SKB_ROUTERALERT;
memcpy(&IP6CB(skb)->ra, nh + optoff + 2, sizeof(IP6CB(skb)->ra));
return true;
}
net_dbg_ratelimited("ipv6_hop_ra: wrong RA length %d\n",
nh[optoff + 1]);
kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR);
return false;
}
/* IOAM */
static bool ipv6_hop_ioam(struct sk_buff *skb, int optoff)
{
struct ioam6_trace_hdr *trace;
struct ioam6_namespace *ns;
struct ioam6_hdr *hdr;
/* Bad alignment (must be 4n-aligned) */
if (optoff & 3)
goto drop;
/* Ignore if IOAM is not enabled on ingress */
if (!__in6_dev_get(skb->dev)->cnf.ioam6_enabled)
goto ignore;
/* Truncated Option header */
hdr = (struct ioam6_hdr *)(skb_network_header(skb) + optoff);
if (hdr->opt_len < 2)
goto drop;
switch (hdr->type) {
case IOAM6_TYPE_PREALLOC:
/* Truncated Pre-allocated Trace header */
if (hdr->opt_len < 2 + sizeof(*trace))
goto drop;
/* Malformed Pre-allocated Trace header */
trace = (struct ioam6_trace_hdr *)((u8 *)hdr + sizeof(*hdr));
if (hdr->opt_len < 2 + sizeof(*trace) + trace->remlen * 4)
goto drop;
/* Ignore if the IOAM namespace is unknown */
ns = ioam6_namespace(ipv6_skb_net(skb), trace->namespace_id);
if (!ns)
goto ignore;
if (!skb_valid_dst(skb))
ip6_route_input(skb);
ioam6_fill_trace_data(skb, ns, trace, true);
break;
default:
break;
}
ignore:
return true;
drop:
kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR);
return false;
}
/* Jumbo payload */
static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
{
const unsigned char *nh = skb_network_header(skb);
SKB_DR(reason);
u32 pkt_len;
if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
net_dbg_ratelimited("ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
nh[optoff+1]);
SKB_DR_SET(reason, IP_INHDR);
goto drop;
}
pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
if (pkt_len <= IPV6_MAXPLEN) {
icmpv6_param_prob_reason(skb, ICMPV6_HDR_FIELD, optoff + 2,
SKB_DROP_REASON_IP_INHDR);
return false;
}
if (ipv6_hdr(skb)->payload_len) {
icmpv6_param_prob_reason(skb, ICMPV6_HDR_FIELD, optoff,
SKB_DROP_REASON_IP_INHDR);
return false;
}
if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
SKB_DR_SET(reason, PKT_TOO_SMALL);
goto drop;
}
if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
goto drop;
IP6CB(skb)->flags |= IP6SKB_JUMBOGRAM;
return true;
drop:
kfree_skb_reason(skb, reason);
return false;
}
/* CALIPSO RFC 5570 */
static bool ipv6_hop_calipso(struct sk_buff *skb, int optoff)
{
const unsigned char *nh = skb_network_header(skb);
if (nh[optoff + 1] < 8)
goto drop;
if (nh[optoff + 6] * 4 + 8 > nh[optoff + 1])
goto drop;
if (!calipso_validate(skb, nh + optoff))
goto drop;
return true;
drop:
kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR);
return false;
}
int ipv6_parse_hopopts(struct sk_buff *skb)
{
struct inet6_skb_parm *opt = IP6CB(skb);
struct net *net = dev_net(skb->dev);
int extlen;
/*
* skb_network_header(skb) is equal to skb->data, and
* skb_network_header_len(skb) is always equal to
* sizeof(struct ipv6hdr) by definition of
* hop-by-hop options.
*/
if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
!pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
((skb_transport_header(skb)[1] + 1) << 3)))) {
fail_and_free:
kfree_skb(skb);
return -1;
}
extlen = (skb_transport_header(skb)[1] + 1) << 3;
if (extlen > net->ipv6.sysctl.max_hbh_opts_len)
goto fail_and_free;
opt->flags |= IP6SKB_HOPBYHOP;
if (ip6_parse_tlv(true, skb, net->ipv6.sysctl.max_hbh_opts_cnt)) {
skb->transport_header += extlen;
opt = IP6CB(skb);
opt->nhoff = sizeof(struct ipv6hdr);
return 1;
}
return -1;
}
/*
* Creating outbound headers.
*
* "build" functions work when skb is filled from head to tail (datagram)
* "push" functions work when headers are added from tail to head (tcp)
*
* In both cases we assume, that caller reserved enough room
* for headers.
*/
static void ipv6_push_rthdr0(struct sk_buff *skb, u8 *proto,
struct ipv6_rt_hdr *opt,
struct in6_addr **addr_p, struct in6_addr *saddr)
{
struct rt0_hdr *phdr, *ihdr;
int hops;
ihdr = (struct rt0_hdr *) opt;
phdr = skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
memcpy(phdr, ihdr, sizeof(struct rt0_hdr));
hops = ihdr->rt_hdr.hdrlen >> 1;
if (hops > 1)
memcpy(phdr->addr, ihdr->addr + 1,
(hops - 1) * sizeof(struct in6_addr));
phdr->addr[hops - 1] = **addr_p;
*addr_p = ihdr->addr;
phdr->rt_hdr.nexthdr = *proto;
*proto = NEXTHDR_ROUTING;
}
static void ipv6_push_rthdr4(struct sk_buff *skb, u8 *proto,
struct ipv6_rt_hdr *opt,
struct in6_addr **addr_p, struct in6_addr *saddr)
{
struct ipv6_sr_hdr *sr_phdr, *sr_ihdr;
int plen, hops;
sr_ihdr = (struct ipv6_sr_hdr *)opt;
plen = (sr_ihdr->hdrlen + 1) << 3;
sr_phdr = skb_push(skb, plen);
memcpy(sr_phdr, sr_ihdr, sizeof(struct ipv6_sr_hdr));
hops = sr_ihdr->first_segment + 1;
memcpy(sr_phdr->segments + 1, sr_ihdr->segments + 1,
(hops - 1) * sizeof(struct in6_addr));
sr_phdr->segments[0] = **addr_p;
*addr_p = &sr_ihdr->segments[sr_ihdr->segments_left];
if (sr_ihdr->hdrlen > hops * 2) {
int tlvs_offset, tlvs_length;
tlvs_offset = (1 + hops * 2) << 3;
tlvs_length = (sr_ihdr->hdrlen - hops * 2) << 3;
memcpy((char *)sr_phdr + tlvs_offset,
(char *)sr_ihdr + tlvs_offset, tlvs_length);
}
#ifdef CONFIG_IPV6_SEG6_HMAC
if (sr_has_hmac(sr_phdr)) {
struct net *net = NULL;
if (skb->dev)
net = dev_net(skb->dev);
else if (skb->sk)
net = sock_net(skb->sk);
WARN_ON(!net);
if (net)
seg6_push_hmac(net, saddr, sr_phdr);
}
#endif
sr_phdr->nexthdr = *proto;
*proto = NEXTHDR_ROUTING;
}
static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
struct ipv6_rt_hdr *opt,
struct in6_addr **addr_p, struct in6_addr *saddr)
{
switch (opt->type) {
case IPV6_SRCRT_TYPE_0:
case IPV6_SRCRT_STRICT:
case IPV6_SRCRT_TYPE_2:
ipv6_push_rthdr0(skb, proto, opt, addr_p, saddr);
break;
case IPV6_SRCRT_TYPE_4:
ipv6_push_rthdr4(skb, proto, opt, addr_p, saddr);
break;
default:
break;
}
}
static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
{
struct ipv6_opt_hdr *h = skb_push(skb, ipv6_optlen(opt));
memcpy(h, opt, ipv6_optlen(opt));
h->nexthdr = *proto;
*proto = type;
}
void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
u8 *proto,
struct in6_addr **daddr, struct in6_addr *saddr)
{
if (opt->srcrt) {
ipv6_push_rthdr(skb, proto, opt->srcrt, daddr, saddr);
/*
* IPV6_RTHDRDSTOPTS is ignored
* unless IPV6_RTHDR is set (RFC3542).
*/
if (opt->dst0opt)
ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
}
if (opt->hopopt)
ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
}
void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
{
if (opt->dst1opt)
ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
}
EXPORT_SYMBOL(ipv6_push_frag_opts);
struct ipv6_txoptions *
ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
{
struct ipv6_txoptions *opt2;
opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
if (opt2) {
long dif = (char *)opt2 - (char *)opt;
memcpy(opt2, opt, opt->tot_len);
if (opt2->hopopt)
*((char **)&opt2->hopopt) += dif;
if (opt2->dst0opt)
*((char **)&opt2->dst0opt) += dif;
if (opt2->dst1opt)
*((char **)&opt2->dst1opt) += dif;
if (opt2->srcrt)
*((char **)&opt2->srcrt) += dif;
refcount_set(&opt2->refcnt, 1);
}
return opt2;
}
EXPORT_SYMBOL_GPL(ipv6_dup_options);
static void ipv6_renew_option(int renewtype,
struct ipv6_opt_hdr **dest,
struct ipv6_opt_hdr *old,
struct ipv6_opt_hdr *new,
int newtype, char **p)
{
struct ipv6_opt_hdr *src;
src = (renewtype == newtype ? new : old);
if (!src)
return;
memcpy(*p, src, ipv6_optlen(src));
*dest = (struct ipv6_opt_hdr *)*p;
*p += CMSG_ALIGN(ipv6_optlen(*dest));
}
/**
* ipv6_renew_options - replace a specific ext hdr with a new one.
*
* @sk: sock from which to allocate memory
* @opt: original options
* @newtype: option type to replace in @opt
* @newopt: new option of type @newtype to replace (user-mem)
*
* Returns a new set of options which is a copy of @opt with the
* option type @newtype replaced with @newopt.
*
* @opt may be NULL, in which case a new set of options is returned
* containing just @newopt.
*
* @newopt may be NULL, in which case the specified option type is
* not copied into the new set of options.
*
* The new set of options is allocated from the socket option memory
* buffer of @sk.
*/
struct ipv6_txoptions *
ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
int newtype, struct ipv6_opt_hdr *newopt)
{
int tot_len = 0;
char *p;
struct ipv6_txoptions *opt2;
if (opt) {
if (newtype != IPV6_HOPOPTS && opt->hopopt)
tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
if (newtype != IPV6_RTHDR && opt->srcrt)
tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
if (newtype != IPV6_DSTOPTS && opt->dst1opt)
tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
}
if (newopt)
tot_len += CMSG_ALIGN(ipv6_optlen(newopt));
if (!tot_len)
return NULL;
tot_len += sizeof(*opt2);
opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
if (!opt2)
return ERR_PTR(-ENOBUFS);
memset(opt2, 0, tot_len);
refcount_set(&opt2->refcnt, 1);
opt2->tot_len = tot_len;
p = (char *)(opt2 + 1);
ipv6_renew_option(IPV6_HOPOPTS, &opt2->hopopt,
(opt ? opt->hopopt : NULL),
newopt, newtype, &p);
ipv6_renew_option(IPV6_RTHDRDSTOPTS, &opt2->dst0opt,
(opt ? opt->dst0opt : NULL),
newopt, newtype, &p);
ipv6_renew_option(IPV6_RTHDR,
(struct ipv6_opt_hdr **)&opt2->srcrt,
(opt ? (struct ipv6_opt_hdr *)opt->srcrt : NULL),
newopt, newtype, &p);
ipv6_renew_option(IPV6_DSTOPTS, &opt2->dst1opt,
(opt ? opt->dst1opt : NULL),
newopt, newtype, &p);
opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
(opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
(opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);
return opt2;
}
struct ipv6_txoptions *__ipv6_fixup_options(struct ipv6_txoptions *opt_space,
struct ipv6_txoptions *opt)
{
/*
* ignore the dest before srcrt unless srcrt is being included.
* --yoshfuji
*/
if (opt->dst0opt && !opt->srcrt) {
if (opt_space != opt) {
memcpy(opt_space, opt, sizeof(*opt_space));
opt = opt_space;
}
opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
opt->dst0opt = NULL;
}
return opt;
}
EXPORT_SYMBOL_GPL(__ipv6_fixup_options);
/**
* fl6_update_dst - update flowi destination address with info given
* by srcrt option, if any.
*
* @fl6: flowi6 for which daddr is to be updated
* @opt: struct ipv6_txoptions in which to look for srcrt opt
* @orig: copy of original daddr address if modified
*
* Returns NULL if no txoptions or no srcrt, otherwise returns orig
* and initial value of fl6->daddr set in orig
*/
struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
const struct ipv6_txoptions *opt,
struct in6_addr *orig)
{
if (!opt || !opt->srcrt)
return NULL;
*orig = fl6->daddr;
switch (opt->srcrt->type) {
case IPV6_SRCRT_TYPE_0:
case IPV6_SRCRT_STRICT:
case IPV6_SRCRT_TYPE_2:
fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr;
break;
case IPV6_SRCRT_TYPE_4:
{
struct ipv6_sr_hdr *srh = (struct ipv6_sr_hdr *)opt->srcrt;
fl6->daddr = srh->segments[srh->segments_left];
break;
}
default:
return NULL;
}
return orig;
}
EXPORT_SYMBOL_GPL(fl6_update_dst);
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