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inany: Helper functions for handling addresses which could be IPv4 or IPv6

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struct tcp_conn stores an address which could be IPv6 or IPv4 using a
union.  We can do this without an additional tag by encoding IPv4 addresses
as IPv4-mapped IPv6 addresses.

This approach is useful wider than the specific place in tcp_conn, so
expose a new 'union inany_addr' like this from a new inany.h.  Along with
that create a number of helper functions to make working with these "inany"
addresses easier.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
David Gibson 2022-11-17 16:58:55 +11:00 committed by Stefano Brivio
parent b65d603e23
commit ca69c3f196
5 changed files with 117 additions and 61 deletions
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6
Makefile
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@ -46,9 +46,9 @@ SRCS = $(PASST_SRCS) $(QRAP_SRCS)
MANPAGES = passt.1 pasta.1 qrap.1
PASST_HEADERS = arch.h arp.h checksum.h conf.h dhcp.h dhcpv6.h icmp.h \
isolation.h lineread.h log.h ndp.h netlink.h packet.h passt.h pasta.h \
pcap.h port_fwd.h siphash.h tap.h tcp.h tcp_conn.h tcp_splice.h udp.h \
util.h
inany.h isolation.h lineread.h log.h ndp.h netlink.h packet.h passt.h \
pasta.h pcap.h port_fwd.h siphash.h tap.h tcp.h tcp_conn.h \
tcp_splice.h udp.h util.h
HEADERS = $(PASST_HEADERS) seccomp.h
# On gcc 11 and 12, with -O2 and -flto, tcp_hash() and siphash_20b(), if

68
inany.h Normal file
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@ -0,0 +1,68 @@
/* SPDX-License-Identifier: AGPL-3.0-or-later
* Copyright Red Hat
* Author: David Gibson <david@gibson.dropbear.id.au>
*
* inany.h - Types and helpers for handling addresses which could be
* IPv6 or IPv4 (encoded as IPv4-mapped IPv6 addresses)
*/
#include <assert.h>
/** union inany_addr - Represents either an IPv4 or IPv6 address
* @a6: Address as an IPv6 address, may be IPv4-mapped
* @v4mapped.zero: All zero-bits for an IPv4 address
* @v4mapped.one: All one-bits for an IPv4 address
* @v4mapped.a4: If @a6 is an IPv4 mapped address, the IPv4 address
*
* @v4mapped shouldn't be accessed except via helpers.
*/
union inany_addr {
struct in6_addr a6;
struct {
uint8_t zero[10];
uint8_t one[2];
struct in_addr a4;
} v4mapped;
};
/** inany_v4 - Extract IPv4 address, if present, from IPv[46] address
* @addr: IPv4 or IPv6 address
*
* Return: IPv4 address if @addr is IPv4, NULL otherwise
*/
static inline const struct in_addr *inany_v4(const union inany_addr *addr)
{
if (!IN6_IS_ADDR_V4MAPPED(&addr->a6))
return NULL;
return &addr->v4mapped.a4;
}
/** inany_equals - Compare two IPv[46] addresses
* @a, @b: IPv[46] addresses
*
* Return: true if @a and @b are the same address
*/
static inline bool inany_equals(const union inany_addr *a,
const union inany_addr *b)
{
return IN6_ARE_ADDR_EQUAL(&a->a6, &b->a6);
}
/** inany_from_af - Set IPv[46] address from IPv4 or IPv6 address
* @aa: Pointer to store IPv[46] address
* @af: Address family of @addr
* @addr: struct in_addr (IPv4) or struct in6_addr (IPv6)
*/
static inline void inany_from_af(union inany_addr *aa, int af, const void *addr)
{
if (af == AF_INET6) {
aa->a6 = *((struct in6_addr *)addr);
} else if (af == AF_INET) {
memset(&aa->v4mapped.zero, 0, sizeof(aa->v4mapped.zero));
memset(&aa->v4mapped.one, 0xff, sizeof(aa->v4mapped.one));
aa->v4mapped.a4 = *((struct in_addr *)addr);
} else {
/* Not valid to call with other address families */
assert(0);
}
}

88
tcp.c
View File

@ -301,6 +301,7 @@
#include "conf.h"
#include "tcp_splice.h"
#include "log.h"
#include "inany.h"
#include "tcp_conn.h"
@ -404,7 +405,7 @@ struct tcp6_l2_head { /* For MSS6 macro: keep in sync with tcp6_l2_buf_t */
#define OPT_SACK 5
#define OPT_TS 8
#define CONN_V4(conn) IN6_IS_ADDR_V4MAPPED(&conn->a.a6)
#define CONN_V4(conn) (!!inany_v4(&(conn)->addr))
#define CONN_V6(conn) (!CONN_V4(conn))
#define CONN_IS_CLOSING(conn) \
((conn->events & ESTABLISHED) && \
@ -438,7 +439,7 @@ static int tcp_sock_init_ext [NUM_PORTS][IP_VERSIONS];
static int tcp_sock_ns [NUM_PORTS][IP_VERSIONS];
/* Table of destinations with very low RTT (assumed to be local), LRU */
static struct in6_addr low_rtt_dst[LOW_RTT_TABLE_SIZE];
static union inany_addr low_rtt_dst[LOW_RTT_TABLE_SIZE];
/* Static buffers */
@ -861,7 +862,7 @@ static int tcp_rtt_dst_low(const struct tcp_tap_conn *conn)
int i;
for (i = 0; i < LOW_RTT_TABLE_SIZE; i++)
if (IN6_ARE_ADDR_EQUAL(&conn->a.a6, low_rtt_dst + i))
if (inany_equals(&conn->addr, low_rtt_dst + i))
return 1;
return 0;
@ -883,7 +884,7 @@ static void tcp_rtt_dst_check(const struct tcp_tap_conn *conn,
return;
for (i = 0; i < LOW_RTT_TABLE_SIZE; i++) {
if (IN6_ARE_ADDR_EQUAL(&conn->a.a6, low_rtt_dst + i))
if (inany_equals(&conn->addr, low_rtt_dst + i))
return;
if (hole == -1 && IN6_IS_ADDR_UNSPECIFIED(low_rtt_dst + i))
hole = i;
@ -895,10 +896,10 @@ static void tcp_rtt_dst_check(const struct tcp_tap_conn *conn,
if (hole == -1)
return;
memcpy(low_rtt_dst + hole++, &conn->a.a6, sizeof(conn->a.a6));
low_rtt_dst[hole++] = conn->addr;
if (hole == LOW_RTT_TABLE_SIZE)
hole = 0;
memcpy(low_rtt_dst + hole, &in6addr_any, sizeof(conn->a.a6));
inany_from_af(low_rtt_dst + hole, AF_INET6, &in6addr_any);
#else
(void)conn;
(void)tinfo;
@ -1187,13 +1188,14 @@ static int tcp_hash_match(const struct tcp_tap_conn *conn,
int af, const void *addr,
in_port_t tap_port, in_port_t sock_port)
{
if (af == AF_INET && CONN_V4(conn) &&
!memcmp(&conn->a.a4.a, addr, sizeof(conn->a.a4.a)) &&
const struct in_addr *a4 = inany_v4(&conn->addr);
if (af == AF_INET && a4 && !memcmp(a4, addr, sizeof(*a4)) &&
conn->tap_port == tap_port && conn->sock_port == sock_port)
return 1;
if (af == AF_INET6 &&
IN6_ARE_ADDR_EQUAL(&conn->a.a6, addr) &&
IN6_ARE_ADDR_EQUAL(&conn->addr.a6, addr) &&
conn->tap_port == tap_port && conn->sock_port == sock_port)
return 1;
@ -1253,11 +1255,13 @@ static unsigned int tcp_hash(const struct ctx *c, int af, const void *addr,
static unsigned int tcp_conn_hash(const struct ctx *c,
const struct tcp_tap_conn *conn)
{
if (CONN_V6(conn))
return tcp_hash(c, AF_INET6, &conn->a.a6,
const struct in_addr *a4 = inany_v4(&conn->addr);
if (a4)
return tcp_hash(c, AF_INET, a4,
conn->tap_port, conn->sock_port);
else
return tcp_hash(c, AF_INET, &conn->a.a4.a,
return tcp_hash(c, AF_INET6, &conn->addr.a6,
conn->tap_port, conn->sock_port);
}
@ -1582,6 +1586,7 @@ static size_t tcp_l2_buf_fill_headers(const struct ctx *c,
void *p, size_t plen,
const uint16_t *check, uint32_t seq)
{
const struct in_addr *a4 = inany_v4(&conn->addr);
size_t ip_len, eth_len;
#define SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq) \
@ -1599,13 +1604,33 @@ do { \
} \
} while (0)
if (CONN_V6(conn)) {
if (a4) {
struct tcp4_l2_buf_t *b = (struct tcp4_l2_buf_t *)p;
ip_len = plen + sizeof(struct iphdr) + sizeof(struct tcphdr);
b->iph.tot_len = htons(ip_len);
b->iph.saddr = a4->s_addr;
b->iph.daddr = c->ip4.addr_seen.s_addr;
if (check)
b->iph.check = *check;
else
tcp_update_check_ip4(b);
SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq);
tcp_update_check_tcp4(b);
eth_len = ip_len + sizeof(struct ethhdr);
if (c->mode == MODE_PASST)
b->vnet_len = htonl(eth_len);
} else {
struct tcp6_l2_buf_t *b = (struct tcp6_l2_buf_t *)p;
ip_len = plen + sizeof(struct ipv6hdr) + sizeof(struct tcphdr);
b->ip6h.payload_len = htons(plen + sizeof(struct tcphdr));
b->ip6h.saddr = conn->a.a6;
b->ip6h.saddr = conn->addr.a6;
if (IN6_IS_ADDR_LINKLOCAL(&b->ip6h.saddr))
b->ip6h.daddr = c->ip6.addr_ll_seen;
else
@ -1621,26 +1646,6 @@ do { \
b->ip6h.flow_lbl[1] = (conn->sock >> 8) & 0xff;
b->ip6h.flow_lbl[2] = (conn->sock >> 0) & 0xff;
eth_len = ip_len + sizeof(struct ethhdr);
if (c->mode == MODE_PASST)
b->vnet_len = htonl(eth_len);
} else {
struct tcp4_l2_buf_t *b = (struct tcp4_l2_buf_t *)p;
ip_len = plen + sizeof(struct iphdr) + sizeof(struct tcphdr);
b->iph.tot_len = htons(ip_len);
b->iph.saddr = conn->a.a4.a.s_addr;
b->iph.daddr = c->ip4.addr_seen.s_addr;
if (check)
b->iph.check = *check;
else
tcp_update_check_ip4(b);
SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq);
tcp_update_check_tcp4(b);
eth_len = ip_len + sizeof(struct ethhdr);
if (c->mode == MODE_PASST)
b->vnet_len = htonl(eth_len);
@ -2144,18 +2149,14 @@ static void tcp_conn_from_tap(struct ctx *c, int af, const void *addr,
if (!(conn->wnd_from_tap = (htons(th->window) >> conn->ws_from_tap)))
conn->wnd_from_tap = 1;
inany_from_af(&conn->addr, af, addr);
if (af == AF_INET) {
sa = (struct sockaddr *)&addr4;
sl = sizeof(addr4);
memset(&conn->a.a4.zero, 0, sizeof(conn->a.a4.zero));
memset(&conn->a.a4.one, 0xff, sizeof(conn->a.a4.one));
memcpy(&conn->a.a4.a, addr, sizeof(conn->a.a4.a));
} else {
sa = (struct sockaddr *)&addr6;
sl = sizeof(addr6);
memcpy(&conn->a.a6, addr, sizeof(conn->a.a6));
}
conn->sock_port = ntohs(th->dest);
@ -2808,7 +2809,7 @@ static void tcp_tap_conn_from_sock(struct ctx *c, union epoll_ref ref,
memcpy(&sa6.sin6_addr, src, sizeof(*src));
}
memcpy(&conn->a.a6, &sa6.sin6_addr, sizeof(conn->a.a6));
inany_from_af(&conn->addr, AF_INET6, &sa6.sin6_addr);
conn->sock_port = ntohs(sa6.sin6_port);
conn->tap_port = ref.r.p.tcp.tcp.index;
@ -2824,15 +2825,12 @@ static void tcp_tap_conn_from_sock(struct ctx *c, union epoll_ref ref,
memcpy(&sa4, sa, sizeof(sa4));
memset(&conn->a.a4.zero, 0, sizeof(conn->a.a4.zero));
memset(&conn->a.a4.one, 0xff, sizeof(conn->a.a4.one));
if (IN4_IS_ADDR_LOOPBACK(&sa4.sin_addr) ||
IN4_IS_ADDR_UNSPECIFIED(&sa4.sin_addr) ||
IN4_ARE_ADDR_EQUAL(&sa4.sin_addr, &c->ip4.addr_seen))
sa4.sin_addr = c->ip4.gw;
conn->a.a4.a = sa4.sin_addr;
inany_from_af(&conn->addr, AF_INET, &sa4.sin_addr);
conn->sock_port = ntohs(sa4.sin_port);
conn->tap_port = ref.r.p.tcp.tcp.index;

15
tcp_conn.h
View File

@ -35,10 +35,7 @@ extern const char *tcp_common_flag_str[];
* @ws_to_tap: Window scaling factor advertised to tap/guest
* @sndbuf: Sending buffer in kernel, rounded to 2 ^ SNDBUF_BITS
* @seq_dup_ack_approx: Last duplicate ACK number sent to tap
* @a.a6: IPv6 remote address, can be IPv4-mapped
* @a.a4.zero: Zero prefix for IPv4-mapped, see RFC 6890, Table 20
* @a.a4.one: Ones prefix for IPv4-mapped
* @a.a4.a: IPv4 address
* @addr: Remote address (IPv4 or IPv6)
* @tap_port: Guest-facing tap port
* @sock_port: Remote, socket-facing port
* @wnd_from_tap: Last window size from tap, unscaled (as received)
@ -108,15 +105,7 @@ struct tcp_tap_conn {
uint8_t seq_dup_ack_approx;
union {
struct in6_addr a6;
struct {
uint8_t zero[10];
uint8_t one[2];
struct in_addr a;
} a4;
} a;
union inany_addr addr;
in_port_t tap_port;
in_port_t sock_port;

1
tcp_splice.c
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@ -52,6 +52,7 @@
#include "passt.h"
#include "log.h"
#include "tcp_splice.h"
#include "inany.h"
#include "tcp_conn.h"