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/* SPDX-License-Identifier: GPL-2.0
*
* Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/
#include <net/route.h>
#include <net/esp.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/ip6_checksum.h>
#define IP6_MF 0x0001
#define IP6_OFFSET 0xFFF8
static inline int skb_maybe_pull_tail(struct sk_buff *skb, unsigned int len, unsigned int max)
{
if (skb_headlen(skb) >= len)
return 0;
if (max > skb->len)
max = skb->len;
if (__pskb_pull_tail(skb, max - skb_headlen(skb)) == NULL)
return -ENOMEM;
if (skb_headlen(skb) < len)
return -EPROTO;
return 0;
}
#define MAX_IP_HDR_LEN 128
static inline int skb_checksum_setup_ip(struct sk_buff *skb, bool recalculate)
{
unsigned int off;
bool fragment;
int err;
fragment = false;
err = skb_maybe_pull_tail(skb, sizeof(struct iphdr), MAX_IP_HDR_LEN);
if (err < 0)
goto out;
if (ip_hdr(skb)->frag_off & htons(IP_OFFSET | IP_MF))
fragment = true;
off = ip_hdrlen(skb);
err = -EPROTO;
if (fragment)
goto out;
switch (ip_hdr(skb)->protocol) {
case IPPROTO_TCP:
err = skb_maybe_pull_tail(skb,
off + sizeof(struct tcphdr),
MAX_IP_HDR_LEN);
if (err < 0)
goto out;
if (!skb_partial_csum_set(skb, off,
offsetof(struct tcphdr, check))) {
err = -EPROTO;
goto out;
}
if (recalculate)
tcp_hdr(skb)->check =
~csum_tcpudp_magic(ip_hdr(skb)->saddr,
ip_hdr(skb)->daddr,
skb->len - off,
IPPROTO_TCP, 0);
break;
case IPPROTO_UDP:
err = skb_maybe_pull_tail(skb,
off + sizeof(struct udphdr),
MAX_IP_HDR_LEN);
if (err < 0)
goto out;
if (!skb_partial_csum_set(skb, off,
offsetof(struct udphdr, check))) {
err = -EPROTO;
goto out;
}
if (recalculate)
udp_hdr(skb)->check =
~csum_tcpudp_magic(ip_hdr(skb)->saddr,
ip_hdr(skb)->daddr,
skb->len - off,
IPPROTO_UDP, 0);
break;
default:
goto out;
}
err = 0;
out:
return err;
}
#define MAX_IPV6_HDR_LEN 256
#define OPT_HDR(type, skb, off) \
(type *)(skb_network_header(skb) + (off))
static inline int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate)
{
int err;
u8 nexthdr;
unsigned int off;
unsigned int len;
bool fragment;
bool done;
fragment = false;
done = false;
off = sizeof(struct ipv6hdr);
err = skb_maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
if (err < 0)
goto out;
nexthdr = ipv6_hdr(skb)->nexthdr;
len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
while (off <= len && !done) {
switch (nexthdr) {
case IPPROTO_DSTOPTS:
case IPPROTO_HOPOPTS:
case IPPROTO_ROUTING: {
struct ipv6_opt_hdr *hp;
err = skb_maybe_pull_tail(skb, off + sizeof(struct ipv6_opt_hdr), MAX_IPV6_HDR_LEN);
if (err < 0)
goto out;
hp = OPT_HDR(struct ipv6_opt_hdr, skb, off);
nexthdr = hp->nexthdr;
off += ipv6_optlen(hp);
break;
}
case IPPROTO_FRAGMENT: {
struct frag_hdr *hp;
err = skb_maybe_pull_tail(skb, off + sizeof(struct frag_hdr), MAX_IPV6_HDR_LEN);
if (err < 0)
goto out;
hp = OPT_HDR(struct frag_hdr, skb, off);
if (hp->frag_off & htons(IP6_OFFSET | IP6_MF))
fragment = true;
nexthdr = hp->nexthdr;
off += sizeof(struct frag_hdr);
break;
}
default:
done = true;
break;
}
}
err = -EPROTO;
if (!done || fragment)
goto out;
switch (nexthdr) {
case IPPROTO_TCP:
err = skb_maybe_pull_tail(skb,
off + sizeof(struct tcphdr),
MAX_IPV6_HDR_LEN);
if (err < 0)
goto out;
if (!skb_partial_csum_set(skb, off,
offsetof(struct tcphdr, check))) {
err = -EPROTO;
goto out;
}
if (recalculate)
tcp_hdr(skb)->check =
~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
&ipv6_hdr(skb)->daddr,
skb->len - off,
IPPROTO_TCP, 0);
break;
case IPPROTO_UDP:
err = skb_maybe_pull_tail(skb,
off + sizeof(struct udphdr),
MAX_IPV6_HDR_LEN);
if (err < 0)
goto out;
if (!skb_partial_csum_set(skb, off,
offsetof(struct udphdr, check))) {
err = -EPROTO;
goto out;
}
if (recalculate)
udp_hdr(skb)->check =
~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
&ipv6_hdr(skb)->daddr,
skb->len - off,
IPPROTO_UDP, 0);
break;
default:
goto out;
}
err = 0;
out:
return err;
}
static inline int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
{
int err;
switch (skb->protocol) {
case htons(ETH_P_IP):
err = skb_checksum_setup_ip(skb, recalculate);
break;
case htons(ETH_P_IPV6):
err = skb_checksum_setup_ipv6(skb, recalculate);
break;
default:
err = -EPROTO;
break;
}
return err;
}
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