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Randomize the TCP initial sequence numbers more thoroughly.

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Obtained from:	OpenBSD
Reviewed by:	jesper, peter, -developers
This commit is contained in:
Kris Kennaway 2001-04-17 18:08:01 +00:00
parent e3ee8974e3
commit f0a04f3f51
8 changed files with 161 additions and 8 deletions
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13
sys/netinet/tcp_input.c
View File

@ -1110,9 +1110,14 @@ tcp_input(m, off0, proto)
tcp_dooptions(tp, optp, optlen, th, &to);
if (iss)
tp->iss = iss;
else
else {
#ifdef TCP_COMPAT_42
tcp_iss += TCP_ISSINCR/2;
tp->iss = tcp_iss;
tcp_iss += TCP_ISSINCR/4;
#else
tp->iss = tcp_rndiss_next();
#endif /* TCP_COMPAT_42 */
}
tp->irs = th->th_seq;
tcp_sendseqinit(tp);
tcp_rcvseqinit(tp);
@ -1643,7 +1648,11 @@ tcp_input(m, off0, proto)
if (thflags & TH_SYN &&
tp->t_state == TCPS_TIME_WAIT &&
SEQ_GT(th->th_seq, tp->rcv_nxt)) {
#ifdef TCP_COMPAT_42
iss = tp->snd_nxt + TCP_ISSINCR;
#else
iss = tcp_rndiss_next();
#endif /* TCP_COMPAT_42 */
tp = tcp_close(tp);
goto findpcb;
}

13
sys/netinet/tcp_reass.c
View File

@ -1110,9 +1110,14 @@ tcp_input(m, off0, proto)
tcp_dooptions(tp, optp, optlen, th, &to);
if (iss)
tp->iss = iss;
else
else {
#ifdef TCP_COMPAT_42
tcp_iss += TCP_ISSINCR/2;
tp->iss = tcp_iss;
tcp_iss += TCP_ISSINCR/4;
#else
tp->iss = tcp_rndiss_next();
#endif /* TCP_COMPAT_42 */
}
tp->irs = th->th_seq;
tcp_sendseqinit(tp);
tcp_rcvseqinit(tp);
@ -1643,7 +1648,11 @@ tcp_input(m, off0, proto)
if (thflags & TH_SYN &&
tp->t_state == TCPS_TIME_WAIT &&
SEQ_GT(th->th_seq, tp->rcv_nxt)) {
#ifdef TCP_COMPAT_42
iss = tp->snd_nxt + TCP_ISSINCR;
#else
iss = tcp_rndiss_next();
#endif /* TCP_COMPAT_42 */
tp = tcp_close(tp);
goto findpcb;
}

2
sys/netinet/tcp_seq.h
View File

@ -81,6 +81,7 @@
#ifdef _KERNEL
extern tcp_cc tcp_ccgen; /* global connection count */
#ifdef TCP_COMPAT_42
/*
* Increment for tcp_iss each second.
* This is designed to increment at the standard 250 KB/s,
@ -96,6 +97,7 @@ extern tcp_cc tcp_ccgen; /* global connection count */
#define TCP_ISSINCR (122*1024 + tcp_random18())
extern tcp_seq tcp_iss; /* tcp initial send seq # */
#endif /* TCP_COMPAT_42 */
#else
#define TCP_ISSINCR (250*1024) /* increment for tcp_iss each second */
#endif /* _KERNEL */

62
sys/netinet/tcp_subr.c
View File

@ -53,6 +53,7 @@
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/protosw.h>
#include <sys/random.h>
#include <vm/vm_zone.h>
@ -181,7 +182,9 @@ tcp_init()
{
int hashsize;
tcp_iss = arc4random(); /* wrong, but better than a constant */
#ifdef TCP_COMPAT_42
tcp_iss = 1; /* wrong */
#endif /* TCP_COMPAT_42 */
tcp_ccgen = 1;
tcp_cleartaocache();
@ -1100,6 +1103,63 @@ tcp6_ctlinput(cmd, sa, d)
}
#endif /* INET6 */
#define TCP_RNDISS_ROUNDS 16
#define TCP_RNDISS_OUT 7200
#define TCP_RNDISS_MAX 30000
u_int8_t tcp_rndiss_sbox[128];
u_int16_t tcp_rndiss_msb;
u_int16_t tcp_rndiss_cnt;
long tcp_rndiss_reseed;
u_int16_t
tcp_rndiss_encrypt(val)
u_int16_t val;
{
u_int16_t sum = 0, i;
for (i = 0; i < TCP_RNDISS_ROUNDS; i++) {
sum += 0x79b9;
val ^= ((u_int16_t)tcp_rndiss_sbox[(val^sum) & 0x7f]) << 7;
val = ((val & 0xff) << 7) | (val >> 8);
}
return val;
}
void
tcp_rndiss_init()
{
struct timeval time;
getmicrotime(&time);
read_random(tcp_rndiss_sbox, sizeof(tcp_rndiss_sbox));
tcp_rndiss_reseed = time.tv_sec + TCP_RNDISS_OUT;
tcp_rndiss_msb = tcp_rndiss_msb == 0x8000 ? 0 : 0x8000;
tcp_rndiss_cnt = 0;
}
tcp_seq
tcp_rndiss_next()
{
u_int16_t tmp;
struct timeval time;
getmicrotime(&time);
if (tcp_rndiss_cnt >= TCP_RNDISS_MAX ||
time.tv_sec > tcp_rndiss_reseed)
tcp_rndiss_init();
read_random(&tmp, sizeof(tmp));
/* (tmp & 0x7fff) ensures a 32768 byte gap between ISS */
return ((tcp_rndiss_encrypt(tcp_rndiss_cnt++) | tcp_rndiss_msb) <<16) |
(tmp & 0x7fff);
}
/*
* When a source quench is received, close congestion window
* to one segment. We will gradually open it again as we proceed.

2
sys/netinet/tcp_timer.c
View File

@ -132,8 +132,8 @@ tcp_slowtimo()
tcp_maxidle = tcp_keepcnt * tcp_keepintvl;
tcp_iss += TCP_ISSINCR/PR_SLOWHZ; /* increment iss */
#ifdef TCP_COMPAT_42
tcp_iss += TCP_ISSINCR/PR_SLOWHZ; /* increment iss */
if ((int)tcp_iss < 0)
tcp_iss = TCP_ISSINCR; /* XXX */
#endif

62
sys/netinet/tcp_timewait.c
View File

@ -53,6 +53,7 @@
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/protosw.h>
#include <sys/random.h>
#include <vm/vm_zone.h>
@ -181,7 +182,9 @@ tcp_init()
{
int hashsize;
tcp_iss = arc4random(); /* wrong, but better than a constant */
#ifdef TCP_COMPAT_42
tcp_iss = 1; /* wrong */
#endif /* TCP_COMPAT_42 */
tcp_ccgen = 1;
tcp_cleartaocache();
@ -1100,6 +1103,63 @@ tcp6_ctlinput(cmd, sa, d)
}
#endif /* INET6 */
#define TCP_RNDISS_ROUNDS 16
#define TCP_RNDISS_OUT 7200
#define TCP_RNDISS_MAX 30000
u_int8_t tcp_rndiss_sbox[128];
u_int16_t tcp_rndiss_msb;
u_int16_t tcp_rndiss_cnt;
long tcp_rndiss_reseed;
u_int16_t
tcp_rndiss_encrypt(val)
u_int16_t val;
{
u_int16_t sum = 0, i;
for (i = 0; i < TCP_RNDISS_ROUNDS; i++) {
sum += 0x79b9;
val ^= ((u_int16_t)tcp_rndiss_sbox[(val^sum) & 0x7f]) << 7;
val = ((val & 0xff) << 7) | (val >> 8);
}
return val;
}
void
tcp_rndiss_init()
{
struct timeval time;
getmicrotime(&time);
read_random(tcp_rndiss_sbox, sizeof(tcp_rndiss_sbox));
tcp_rndiss_reseed = time.tv_sec + TCP_RNDISS_OUT;
tcp_rndiss_msb = tcp_rndiss_msb == 0x8000 ? 0 : 0x8000;
tcp_rndiss_cnt = 0;
}
tcp_seq
tcp_rndiss_next()
{
u_int16_t tmp;
struct timeval time;
getmicrotime(&time);
if (tcp_rndiss_cnt >= TCP_RNDISS_MAX ||
time.tv_sec > tcp_rndiss_reseed)
tcp_rndiss_init();
read_random(&tmp, sizeof(tmp));
/* (tmp & 0x7fff) ensures a 32768 byte gap between ISS */
return ((tcp_rndiss_encrypt(tcp_rndiss_cnt++) | tcp_rndiss_msb) <<16) |
(tmp & 0x7fff);
}
/*
* When a source quench is received, close congestion window
* to one segment. We will gradually open it again as we proceed.

11
sys/netinet/tcp_usrreq.c
View File

@ -761,7 +761,12 @@ tcp_connect(tp, nam, p)
tcpstat.tcps_connattempt++;
tp->t_state = TCPS_SYN_SENT;
callout_reset(tp->tt_keep, tcp_keepinit, tcp_timer_keep, tp);
tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2;
#ifdef TCP_COMPAT_42
tp->iss = tcp_iss;
tcp_iss += TCP_ISSINCR/2;
#else /* TCP_COMPAT_42 */
tp->iss = tcp_rndiss_next();
#endif /* !TCP_COMPAT_42 */
tcp_sendseqinit(tp);
/*
@ -853,7 +858,11 @@ tcp6_connect(tp, nam, p)
tcpstat.tcps_connattempt++;
tp->t_state = TCPS_SYN_SENT;
callout_reset(tp->tt_keep, tcp_keepinit, tcp_timer_keep, tp);
#ifdef TCP_COMPAT_42
tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2;
#else
tp->iss = tcp_rndiss_next();
#endif /* TCP_COMPAT_42 */
tcp_sendseqinit(tp);
/*

4
sys/netinet/tcp_var.h
View File

@ -409,6 +409,10 @@ void tcp_trace __P((int, int, struct tcpcb *, void *, struct tcphdr *,
extern struct pr_usrreqs tcp_usrreqs;
extern u_long tcp_sendspace;
extern u_long tcp_recvspace;
void tcp_rndiss_init __P((void));
tcp_seq tcp_rndiss_next __P((void));
u_int16_t
tcp_rndiss_encrypt __P((u_int16_t));
#endif /* _KERNEL */