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linux/net/core/utils.c
Praveen Chaudhary 420e4a521c net: Fix skb->csum update in inet_proto_csum_replace16(). 
[ Upstream commit 189c9b1e94 ]

skb->csum is updated incorrectly, when manipulation for
NF_NAT_MANIP_SRC\DST is done on IPV6 packet.

Fix:
There is no need to update skb->csum in inet_proto_csum_replace16(),
because update in two fields a.) IPv6 src/dst address and b.) L4 header
checksum cancels each other for skb->csum calculation. Whereas
inet_proto_csum_replace4 function needs to update skb->csum, because
update in 3 fields a.) IPv4 src/dst address, b.) IPv4 Header checksum
and c.) L4 header checksum results in same diff as L4 Header checksum
for skb->csum calculation.

[ pablo@netfilter.org: a few comestic documentation edits ]
Signed-off-by: Praveen Chaudhary <pchaudhary@linkedin.com>
Signed-off-by: Zhenggen Xu <zxu@linkedin.com>
Signed-off-by: Andy Stracner <astracner@linkedin.com>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-02-05 21:22:52 +00:00

487 lines
12 KiB
C
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Generic address resultion entity
*
* Authors:
* net_random Alan Cox
* net_ratelimit Andi Kleen
* in{4,6}_pton YOSHIFUJI Hideaki, Copyright (C)2006 USAGI/WIDE Project
*
* Created by Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
*/
#include <linux/module.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/ctype.h>
#include <linux/inet.h>
#include <linux/mm.h>
#include <linux/net.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/percpu.h>
#include <linux/init.h>
#include <linux/ratelimit.h>
#include <linux/socket.h>
#include <net/sock.h>
#include <net/net_ratelimit.h>
#include <net/ipv6.h>
#include <asm/byteorder.h>
#include <linux/uaccess.h>
DEFINE_RATELIMIT_STATE(net_ratelimit_state, 5 * HZ, 10);
/*
* All net warning printk()s should be guarded by this function.
*/
int net_ratelimit(void)
{
return __ratelimit(&net_ratelimit_state);
}
EXPORT_SYMBOL(net_ratelimit);
/*
* Convert an ASCII string to binary IP.
* This is outside of net/ipv4/ because various code that uses IP addresses
* is otherwise not dependent on the TCP/IP stack.
*/
__be32 in_aton(const char *str)
{
unsigned int l;
unsigned int val;
int i;
l = 0;
for (i = 0; i < 4; i++) {
l <<= 8;
if (*str != '\0') {
val = 0;
while (*str != '\0' && *str != '.' && *str != '\n') {
val *= 10;
val += *str - '0';
str++;
}
l |= val;
if (*str != '\0')
str++;
}
}
return htonl(l);
}
EXPORT_SYMBOL(in_aton);
#define IN6PTON_XDIGIT 0x00010000
#define IN6PTON_DIGIT 0x00020000
#define IN6PTON_COLON_MASK 0x00700000
#define IN6PTON_COLON_1 0x00100000 /* single : requested */
#define IN6PTON_COLON_2 0x00200000 /* second : requested */
#define IN6PTON_COLON_1_2 0x00400000 /* :: requested */
#define IN6PTON_DOT 0x00800000 /* . */
#define IN6PTON_DELIM 0x10000000
#define IN6PTON_NULL 0x20000000 /* first/tail */
#define IN6PTON_UNKNOWN 0x40000000
static inline int xdigit2bin(char c, int delim)
{
int val;
if (c == delim || c == '\0')
return IN6PTON_DELIM;
if (c == ':')
return IN6PTON_COLON_MASK;
if (c == '.')
return IN6PTON_DOT;
val = hex_to_bin(c);
if (val >= 0)
return val | IN6PTON_XDIGIT | (val < 10 ? IN6PTON_DIGIT : 0);
if (delim == -1)
return IN6PTON_DELIM;
return IN6PTON_UNKNOWN;
}
/**
* in4_pton - convert an IPv4 address from literal to binary representation
* @src: the start of the IPv4 address string
* @srclen: the length of the string, -1 means strlen(src)
* @dst: the binary (u8[4] array) representation of the IPv4 address
* @delim: the delimiter of the IPv4 address in @src, -1 means no delimiter
* @end: A pointer to the end of the parsed string will be placed here
*
* Return one on success, return zero when any error occurs
* and @end will point to the end of the parsed string.
*
*/
int in4_pton(const char *src, int srclen,
u8 *dst,
int delim, const char **end)
{
const char *s;
u8 *d;
u8 dbuf[4];
int ret = 0;
int i;
int w = 0;
if (srclen < 0)
srclen = strlen(src);
s = src;
d = dbuf;
i = 0;
while (1) {
int c;
c = xdigit2bin(srclen > 0 ? *s : '\0', delim);
if (!(c & (IN6PTON_DIGIT | IN6PTON_DOT | IN6PTON_DELIM | IN6PTON_COLON_MASK))) {
goto out;
}
if (c & (IN6PTON_DOT | IN6PTON_DELIM | IN6PTON_COLON_MASK)) {
if (w == 0)
goto out;
*d++ = w & 0xff;
w = 0;
i++;
if (c & (IN6PTON_DELIM | IN6PTON_COLON_MASK)) {
if (i != 4)
goto out;
break;
}
goto cont;
}
w = (w * 10) + c;
if ((w & 0xffff) > 255) {
goto out;
}
cont:
if (i >= 4)
goto out;
s++;
srclen--;
}
ret = 1;
memcpy(dst, dbuf, sizeof(dbuf));
out:
if (end)
*end = s;
return ret;
}
EXPORT_SYMBOL(in4_pton);
/**
* in6_pton - convert an IPv6 address from literal to binary representation
* @src: the start of the IPv6 address string
* @srclen: the length of the string, -1 means strlen(src)
* @dst: the binary (u8[16] array) representation of the IPv6 address
* @delim: the delimiter of the IPv6 address in @src, -1 means no delimiter
* @end: A pointer to the end of the parsed string will be placed here
*
* Return one on success, return zero when any error occurs
* and @end will point to the end of the parsed string.
*
*/
int in6_pton(const char *src, int srclen,
u8 *dst,
int delim, const char **end)
{
const char *s, *tok = NULL;
u8 *d, *dc = NULL;
u8 dbuf[16];
int ret = 0;
int i;
int state = IN6PTON_COLON_1_2 | IN6PTON_XDIGIT | IN6PTON_NULL;
int w = 0;
memset(dbuf, 0, sizeof(dbuf));
s = src;
d = dbuf;
if (srclen < 0)
srclen = strlen(src);
while (1) {
int c;
c = xdigit2bin(srclen > 0 ? *s : '\0', delim);
if (!(c & state))
goto out;
if (c & (IN6PTON_DELIM | IN6PTON_COLON_MASK)) {
/* process one 16-bit word */
if (!(state & IN6PTON_NULL)) {
*d++ = (w >> 8) & 0xff;
*d++ = w & 0xff;
}
w = 0;
if (c & IN6PTON_DELIM) {
/* We've processed last word */
break;
}
/*
* COLON_1 => XDIGIT
* COLON_2 => XDIGIT|DELIM
* COLON_1_2 => COLON_2
*/
switch (state & IN6PTON_COLON_MASK) {
case IN6PTON_COLON_2:
dc = d;
state = IN6PTON_XDIGIT | IN6PTON_DELIM;
if (dc - dbuf >= sizeof(dbuf))
state |= IN6PTON_NULL;
break;
case IN6PTON_COLON_1|IN6PTON_COLON_1_2:
state = IN6PTON_XDIGIT | IN6PTON_COLON_2;
break;
case IN6PTON_COLON_1:
state = IN6PTON_XDIGIT;
break;
case IN6PTON_COLON_1_2:
state = IN6PTON_COLON_2;
break;
default:
state = 0;
}
tok = s + 1;
goto cont;
}
if (c & IN6PTON_DOT) {
ret = in4_pton(tok ? tok : s, srclen + (int)(s - tok), d, delim, &s);
if (ret > 0) {
d += 4;
break;
}
goto out;
}
w = (w << 4) | (0xff & c);
state = IN6PTON_COLON_1 | IN6PTON_DELIM;
if (!(w & 0xf000)) {
state |= IN6PTON_XDIGIT;
}
if (!dc && d + 2 < dbuf + sizeof(dbuf)) {
state |= IN6PTON_COLON_1_2;
state &= ~IN6PTON_DELIM;
}
if (d + 2 >= dbuf + sizeof(dbuf)) {
state &= ~(IN6PTON_COLON_1|IN6PTON_COLON_1_2);
}
cont:
if ((dc && d + 4 < dbuf + sizeof(dbuf)) ||
d + 4 == dbuf + sizeof(dbuf)) {
state |= IN6PTON_DOT;
}
if (d >= dbuf + sizeof(dbuf)) {
state &= ~(IN6PTON_XDIGIT|IN6PTON_COLON_MASK);
}
s++;
srclen--;
}
i = 15; d--;
if (dc) {
while (d >= dc)
dst[i--] = *d--;
while (i >= dc - dbuf)
dst[i--] = 0;
while (i >= 0)
dst[i--] = *d--;
} else
memcpy(dst, dbuf, sizeof(dbuf));
ret = 1;
out:
if (end)
*end = s;
return ret;
}
EXPORT_SYMBOL(in6_pton);
static int inet4_pton(const char *src, u16 port_num,
struct sockaddr_storage *addr)
{
struct sockaddr_in *addr4 = (struct sockaddr_in *)addr;
int srclen = strlen(src);
if (srclen > INET_ADDRSTRLEN)
return -EINVAL;
if (in4_pton(src, srclen, (u8 *)&addr4->sin_addr.s_addr,
'\n', NULL) == 0)
return -EINVAL;
addr4->sin_family = AF_INET;
addr4->sin_port = htons(port_num);
return 0;
}
static int inet6_pton(struct net *net, const char *src, u16 port_num,
struct sockaddr_storage *addr)
{
struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)addr;
const char *scope_delim;
int srclen = strlen(src);
if (srclen > INET6_ADDRSTRLEN)
return -EINVAL;
if (in6_pton(src, srclen, (u8 *)&addr6->sin6_addr.s6_addr,
'%', &scope_delim) == 0)
return -EINVAL;
if (ipv6_addr_type(&addr6->sin6_addr) & IPV6_ADDR_LINKLOCAL &&
src + srclen != scope_delim && *scope_delim == '%') {
struct net_device *dev;
char scope_id[16];
size_t scope_len = min_t(size_t, sizeof(scope_id) - 1,
src + srclen - scope_delim - 1);
memcpy(scope_id, scope_delim + 1, scope_len);
scope_id[scope_len] = '\0';
dev = dev_get_by_name(net, scope_id);
if (dev) {
addr6->sin6_scope_id = dev->ifindex;
dev_put(dev);
} else if (kstrtouint(scope_id, 0, &addr6->sin6_scope_id)) {
return -EINVAL;
}
}
addr6->sin6_family = AF_INET6;
addr6->sin6_port = htons(port_num);
return 0;
}
/**
* inet_pton_with_scope - convert an IPv4/IPv6 and port to socket address
* @net: net namespace (used for scope handling)
* @af: address family, AF_INET, AF_INET6 or AF_UNSPEC for either
* @src: the start of the address string
* @port: the start of the port string (or NULL for none)
* @addr: output socket address
*
* Return zero on success, return errno when any error occurs.
*/
int inet_pton_with_scope(struct net *net, __kernel_sa_family_t af,
const char *src, const char *port, struct sockaddr_storage *addr)
{
u16 port_num;
int ret = -EINVAL;
if (port) {
if (kstrtou16(port, 0, &port_num))
return -EINVAL;
} else {
port_num = 0;
}
switch (af) {
case AF_INET:
ret = inet4_pton(src, port_num, addr);
break;
case AF_INET6:
ret = inet6_pton(net, src, port_num, addr);
break;
case AF_UNSPEC:
ret = inet4_pton(src, port_num, addr);
if (ret)
ret = inet6_pton(net, src, port_num, addr);
break;
default:
pr_err("unexpected address family %d\n", af);
}
return ret;
}
EXPORT_SYMBOL(inet_pton_with_scope);
bool inet_addr_is_any(struct sockaddr *addr)
{
if (addr->sa_family == AF_INET6) {
struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)addr;
const struct sockaddr_in6 in6_any =
{ .sin6_addr = IN6ADDR_ANY_INIT };
if (!memcmp(in6->sin6_addr.s6_addr,
in6_any.sin6_addr.s6_addr, 16))
return true;
} else if (addr->sa_family == AF_INET) {
struct sockaddr_in *in = (struct sockaddr_in *)addr;
if (in->sin_addr.s_addr == htonl(INADDR_ANY))
return true;
} else {
pr_warn("unexpected address family %u\n", addr->sa_family);
}
return false;
}
EXPORT_SYMBOL(inet_addr_is_any);
void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
__be32 from, __be32 to, bool pseudohdr)
{
if (skb->ip_summed != CHECKSUM_PARTIAL) {
csum_replace4(sum, from, to);
if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
skb->csum = ~csum_add(csum_sub(~(skb->csum),
(__force __wsum)from),
(__force __wsum)to);
} else if (pseudohdr)
*sum = ~csum_fold(csum_add(csum_sub(csum_unfold(*sum),
(__force __wsum)from),
(__force __wsum)to));
}
EXPORT_SYMBOL(inet_proto_csum_replace4);
/**
* inet_proto_csum_replace16 - update layer 4 header checksum field
* @sum: Layer 4 header checksum field
* @skb: sk_buff for the packet
* @from: old IPv6 address
* @to: new IPv6 address
* @pseudohdr: True if layer 4 header checksum includes pseudoheader
*
* Update layer 4 header as per the update in IPv6 src/dst address.
*
* There is no need to update skb->csum in this function, because update in two
* fields a.) IPv6 src/dst address and b.) L4 header checksum cancels each other
* for skb->csum calculation. Whereas inet_proto_csum_replace4 function needs to
* update skb->csum, because update in 3 fields a.) IPv4 src/dst address,
* b.) IPv4 Header checksum and c.) L4 header checksum results in same diff as
* L4 Header checksum for skb->csum calculation.
*/
void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
const __be32 *from, const __be32 *to,
bool pseudohdr)
{
__be32 diff[] = {
~from[0], ~from[1], ~from[2], ~from[3],
to[0], to[1], to[2], to[3],
};
if (skb->ip_summed != CHECKSUM_PARTIAL) {
*sum = csum_fold(csum_partial(diff, sizeof(diff),
~csum_unfold(*sum)));
} else if (pseudohdr)
*sum = ~csum_fold(csum_partial(diff, sizeof(diff),
csum_unfold(*sum)));
}
EXPORT_SYMBOL(inet_proto_csum_replace16);
void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb,
__wsum diff, bool pseudohdr)
{
if (skb->ip_summed != CHECKSUM_PARTIAL) {
*sum = csum_fold(csum_add(diff, ~csum_unfold(*sum)));
if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
skb->csum = ~csum_add(diff, ~skb->csum);
} else if (pseudohdr) {
*sum = ~csum_fold(csum_add(diff, csum_unfold(*sum)));
}
}
EXPORT_SYMBOL(inet_proto_csum_replace_by_diff);
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