Get rid of the RANDOM_IP_ID option and make it a sysctl. NetBSD

have already done this, so I have styled the patch on their work:

        1) introduce a ip_newid() static inline function that checks
        the sysctl and then decides if it should return a sequential
        or random IP ID.

        2) named the sysctl net.inet.ip.random_id

        3) IPv6 flow IDs and fragment IDs are now always random.
        Flow IDs and frag IDs are significantly less common in the
        IPv6 world (ie. rarely generated per-packet), so there should
        be smaller performance concerns.

The sysctl defaults to 0 (sequential IP IDs).

Reviewed by:	andre, silby, mlaier, ume
Based on:	NetBSD
MFC after:	2 months

8 files changed, 1 insertions, 46 deletions

diff --git a/sys/netinet6/frag6.c b/sys/netinet6/frag6.c
index f8a86a1fac0a..8be7d5247806 100644
--- a/sys/netinet6/frag6.c
+++ b/sys/netinet6/frag6.c
@@ -30,8 +30,6 @@
  * SUCH DAMAGE.
  */
 
-#include "opt_random_ip_id.h"
-
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/malloc.h>
@@ -98,9 +96,6 @@ frag6_init()
 
 	IP6Q_LOCK_INIT();
 
-#ifndef RANDOM_IP_ID
-	ip6_id = arc4random();
-#endif
 	ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q;
 }
 
diff --git a/sys/netinet6/in6_pcb.c b/sys/netinet6/in6_pcb.c
index 48d153f61229..7639919e8a84 100644
--- a/sys/netinet6/in6_pcb.c
+++ b/sys/netinet6/in6_pcb.c
@@ -65,7 +65,6 @@
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
-#include "opt_random_ip_id.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -389,11 +388,7 @@ in6_pcbconnect(inp, nam, cred)
 	inp->in6p_flowinfo &= ~IPV6_FLOWLABEL_MASK;
 	if (inp->in6p_flags & IN6P_AUTOFLOWLABEL)
 		inp->in6p_flowinfo |=
-#ifdef RANDOM_IP_ID
 		    (htonl(ip6_randomflowlabel()) & IPV6_FLOWLABEL_MASK);
-#else
-		    (htonl(ip6_flow_seq++) & IPV6_FLOWLABEL_MASK);
-#endif
 
 	in_pcbrehash(inp);
 #ifdef IPSEC
diff --git a/sys/netinet6/in6_proto.c b/sys/netinet6/in6_proto.c
index 2d1d8dc79765..d4edbec6bf50 100644
--- a/sys/netinet6/in6_proto.c
+++ b/sys/netinet6/in6_proto.c
@@ -64,7 +64,6 @@
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
-#include "opt_random_ip_id.h"
 
 #include <sys/param.h>
 #include <sys/socket.h>
@@ -290,9 +289,6 @@ int	ip6_maxfrags;	/* initialized in frag6.c:frag6_init() */
 int	ip6_log_interval = 5;
 int	ip6_hdrnestlimit = 50;	/* appropriate? */
 int	ip6_dad_count = 1;	/* DupAddrDetectionTransmits */
-#ifndef RANDOM_IP_ID
-u_int32_t ip6_flow_seq;
-#endif
 int	ip6_auto_flowlabel = 1;
 int	ip6_gif_hlim = 0;
 int	ip6_use_deprecated = 1;	/* allow deprecated addr (RFC2462 5.5.4) */
@@ -300,9 +296,6 @@ int	ip6_rr_prune = 5;	/* router renumbering prefix
 				 * walk list every 5 sec. */
 int	ip6_v6only = 1;
 
-#ifndef RANDOM_IP_ID
-u_int32_t ip6_id = 0UL;
-#endif
 int	ip6_keepfaith = 0;
 time_t	ip6_log_time = (time_t)0L;
 
diff --git a/sys/netinet6/ip6_id.c b/sys/netinet6/ip6_id.c
index ca193b899016..cb75277b746d 100644
--- a/sys/netinet6/ip6_id.c
+++ b/sys/netinet6/ip6_id.c
@@ -86,8 +86,6 @@
  * This avoids reuse issues caused by reseeding.
  */
 
-#include "opt_random_ip_id.h"
-
 #include <sys/types.h>
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -100,8 +98,6 @@
 #include <netinet/ip6.h>
 #include <netinet6/ip6_var.h>
 
-#ifdef RANDOM_IP_ID
-
 #ifndef INT32_MAX
 #define INT32_MAX	0x7fffffffU
 #endif
@@ -267,5 +263,3 @@ ip6_randomflowlabel(void)
 
 	return randomid(&randomtab_20) & 0xfffff;
 }
-
-#endif /* RANDOM_IP_ID */
diff --git a/sys/netinet6/ip6_input.c b/sys/netinet6/ip6_input.c
index a22eb12c2ea4..ac24f972743d 100644
--- a/sys/netinet6/ip6_input.c
+++ b/sys/netinet6/ip6_input.c
@@ -66,7 +66,6 @@
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
 #include "opt_pfil_hooks.h"
-#include "opt_random_ip_id.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -197,9 +196,6 @@ ip6_init()
 	addrsel_policy_init();
 	nd6_init();
 	frag6_init();
-#ifndef RANDOM_IP_ID
-	ip6_flow_seq = arc4random();
-#endif
 	ip6_desync_factor = arc4random() % MAX_TEMP_DESYNC_FACTOR;
 }
 
diff --git a/sys/netinet6/ip6_output.c b/sys/netinet6/ip6_output.c
index b955f40e2805..f5c35594e8ed 100644
--- a/sys/netinet6/ip6_output.c
+++ b/sys/netinet6/ip6_output.c
@@ -66,7 +66,6 @@
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
 #include "opt_pfil_hooks.h"
-#include "opt_random_ip_id.h"
 
 #include <sys/param.h>
 #include <sys/malloc.h>
@@ -1036,11 +1035,7 @@ skip_ipsec2:;
 	} else {
 		struct mbuf **mnext, *m_frgpart;
 		struct ip6_frag *ip6f;
-#ifdef RANDOM_IP_ID
 		u_int32_t id = htonl(ip6_randomid());
-#else
-		u_int32_t id = htonl(ip6_id++);
-#endif
 		u_char nextproto;
 		struct ip6ctlparam ip6cp;
 		u_int32_t mtu32;
diff --git a/sys/netinet6/ip6_var.h b/sys/netinet6/ip6_var.h
index 99edc4503fff..36bf36dfcc3a 100644
--- a/sys/netinet6/ip6_var.h
+++ b/sys/netinet6/ip6_var.h
@@ -283,9 +283,6 @@ struct ip6aux {
 #define	IPV6_MINMTU		0x04	/* use minimum MTU (IPV6_USE_MIN_MTU) */
 
 extern struct	ip6stat ip6stat;	/* statistics */
-#ifndef RANDOM_IP_ID
-extern u_int32_t ip6_id;		/* fragment identifier */
-#endif
 extern int	ip6_defhlim;		/* default hop limit */
 extern int	ip6_defmcasthlim;	/* default multicast hop limit */
 extern int	ip6_forwarding;		/* act as router? */
@@ -309,9 +306,6 @@ extern time_t	ip6_log_time;
 extern int	ip6_hdrnestlimit; /* upper limit of # of extension headers */
 extern int	ip6_dad_count;		/* DupAddrDetectionTransmits */
 
-#ifndef RANDOM_IP_ID
-extern u_int32_t ip6_flow_seq;
-#endif
 extern int ip6_auto_flowlabel;
 extern int ip6_auto_linklocal;
 
@@ -399,10 +393,8 @@ struct in6_addr *in6_selectsrc __P((struct sockaddr_in6 *,
 int in6_selectroute __P((struct sockaddr_in6 *, struct ip6_pktopts *,
 	struct ip6_moptions *, struct route_in6 *, struct ifnet **,
 	struct rtentry **, int));
-#ifdef RANDOM_IP_ID
 u_int32_t ip6_randomid __P((void));
 u_int32_t ip6_randomflowlabel __P((void));
-#endif
 #endif /* _KERNEL */
 
 #endif /* !_NETINET6_IP6_VAR_H_ */
diff --git a/sys/netinet6/ipsec.c b/sys/netinet6/ipsec.c
index f57a7db8e489..13d2feb667a3 100644
--- a/sys/netinet6/ipsec.c
+++ b/sys/netinet6/ipsec.c
@@ -37,7 +37,6 @@
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
-#include "opt_random_ip_id.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -2156,11 +2155,7 @@ ipsec4_encapsulate(m, sav)
 		ipseclog((LOG_ERR, "IPv4 ipsec: size exceeds limit: "
 		    "leave ip_len as is (invalid packet)\n"));
 	}
-#ifdef RANDOM_IP_ID
-	ip->ip_id = ip_randomid();
-#else
-	ip->ip_id = htons(ip_id++);
-#endif
+	ip->ip_id = ip_newid();
 	bcopy(&((struct sockaddr_in *)&sav->sah->saidx.src)->sin_addr,
 		&ip->ip_src, sizeof(ip->ip_src));
 	bcopy(&((struct sockaddr_in *)&sav->sah->saidx.dst)->sin_addr,