d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Replacing MD5 by SipHash improves the performance of the TCP time stamp

Browse Source 
initialisation, which is important when the host is dealing with a
SYN flood.
This affects the computation of the initial TCP sequence number for
the client side.
This has been discussed with secteam@.

Reviewed by:		gallatin@
Sponsored by:		Netflix, Inc.
Differential Revision:	https://reviews.freebsd.org/D21616
This commit is contained in:
tuexen 2019-09-28 13:13:23 +00:00
parent 09c42850dd
commit dc3d530b6c
1 changed files with 18 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
sys/netinet/tcp_subr.c
View File

@ -126,7 +126,7 @@ __FBSDID("$FreeBSD$");
#include <netipsec/ipsec_support.h>
#include <machine/in_cksum.h>
#include <sys/md5.h>
#include <crypto/siphash/siphash.h>
#include <security/mac/mac_framework.h>
@ -242,7 +242,7 @@ VNET_DEFINE(uma_zone_t, sack_hole_zone);
VNET_DEFINE(struct hhook_head *, tcp_hhh[HHOOK_TCP_LAST+1]);
#endif
#define TS_OFFSET_SECRET_LENGTH 32
#define TS_OFFSET_SECRET_LENGTH SIPHASH_KEY_LENGTH
VNET_DEFINE_STATIC(u_char, ts_offset_secret[TS_OFFSET_SECRET_LENGTH]);
#define V_ts_offset_secret VNET(ts_offset_secret)
@ -2621,30 +2621,32 @@ tcp6_ctlinput(int cmd, struct sockaddr *sa, void *d)
static uint32_t
tcp_keyed_hash(struct in_conninfo *inc, u_char *key, u_int len)
{
MD5_CTX ctx;
uint32_t hash[4];
SIPHASH_CTX ctx;
uint32_t hash[2];
MD5Init(&ctx);
MD5Update(&ctx, &inc->inc_fport, sizeof(uint16_t));
MD5Update(&ctx, &inc->inc_lport, sizeof(uint16_t));
KASSERT(len >= SIPHASH_KEY_LENGTH,
("%s: keylen %u too short ", __func__, len));
SipHash24_Init(&ctx);
SipHash_SetKey(&ctx, (uint8_t *)key);
SipHash_Update(&ctx, &inc->inc_fport, sizeof(uint16_t));
SipHash_Update(&ctx, &inc->inc_lport, sizeof(uint16_t));
switch (inc->inc_flags & INC_ISIPV6) {
#ifdef INET
case 0:
MD5Update(&ctx, &inc->inc_faddr, sizeof(struct in_addr));
MD5Update(&ctx, &inc->inc_laddr, sizeof(struct in_addr));
SipHash_Update(&ctx, &inc->inc_faddr, sizeof(struct in_addr));
SipHash_Update(&ctx, &inc->inc_laddr, sizeof(struct in_addr));
break;
#endif
#ifdef INET6
case INC_ISIPV6:
MD5Update(&ctx, &inc->inc6_faddr, sizeof(struct in6_addr));
MD5Update(&ctx, &inc->inc6_laddr, sizeof(struct in6_addr));
SipHash_Update(&ctx, &inc->inc6_faddr, sizeof(struct in6_addr));
SipHash_Update(&ctx, &inc->inc6_laddr, sizeof(struct in6_addr));
break;
#endif
}
MD5Update(&ctx, key, len);
MD5Final((unsigned char *)hash, &ctx);
SipHash_Final((uint8_t *)hash, &ctx);
return (hash[0]);
return (hash[0] ^ hash[1]);
}
uint32_t
@ -2711,7 +2713,7 @@ tcp_new_ts_offset(struct in_conninfo *inc)
#define ISN_BYTES_PER_SECOND 1048576
#define ISN_STATIC_INCREMENT 4096
#define ISN_RANDOM_INCREMENT (4096 - 1)
#define ISN_SECRET_LENGTH 32
#define ISN_SECRET_LENGTH SIPHASH_KEY_LENGTH
VNET_DEFINE_STATIC(u_char, isn_secret[ISN_SECRET_LENGTH]);
VNET_DEFINE_STATIC(int, isn_last);
@ -2740,7 +2742,7 @@ tcp_new_isn(struct in_conninfo *inc)
V_isn_last_reseed = ticks;
}
/* Compute the md5 hash and return the ISN. */
/* Compute the hash and return the ISN. */
new_isn = (tcp_seq)tcp_keyed_hash(inc, V_isn_secret,
sizeof(V_isn_secret));
V_isn_offset += ISN_STATIC_INCREMENT +