Index: sys/net/bpf.h
===================================================================
RCS file: /cvs/src/sys/net/bpf.h,v
retrieving revision 1.69
diff -u -p -r1.69 bpf.h
--- sys/net/bpf.h	18 Jun 2020 23:27:58 -0000	1.69
+++ sys/net/bpf.h	16 Jul 2020 07:08:52 -0000
@@ -237,6 +237,7 @@ struct bpf_hdr {
 #define		BPF_MEM		0x60
 #define		BPF_LEN		0x80
 #define		BPF_MSH		0xa0
+#define		BPF_RND		0xc0
 
 /* alu/jmp fields */
 #define BPF_OP(code)	((code) & 0xf0)
Index: sys/net/bpf_filter.c
===================================================================
RCS file: /cvs/src/sys/net/bpf_filter.c,v
retrieving revision 1.33
diff -u -p -r1.33 bpf_filter.c
--- sys/net/bpf_filter.c	8 Sep 2017 05:36:53 -0000	1.33
+++ sys/net/bpf_filter.c	16 Jul 2020 07:08:52 -0000
@@ -199,6 +199,10 @@ _bpf_filter(const struct bpf_insn *pc, c
 			X = wirelen;
 			continue;
 
+		case BPF_LD|BPF_W|BPF_RND:
+			A = arc4random();
+			continue;
+
 		case BPF_LD|BPF_W|BPF_IND:
 			k = X + pc->k;
 			A = ops->ldw(pkt, k, &err);
@@ -414,6 +418,7 @@ bpf_validate(struct bpf_insn *f, int len
 					return 0;
 				break;
 			case BPF_LEN:
+			case BPF_RND:
 				break;
 			default:
 				return 0;
Index: share/man/man4/bpf.4
===================================================================
RCS file: /cvs/src/share/man/man4/bpf.4,v
retrieving revision 1.41
diff -u -p -r1.41 bpf.4
--- share/man/man4/bpf.4	25 Apr 2019 18:26:16 -0000	1.41
+++ share/man/man4/bpf.4	16 Jul 2020 07:08:52 -0000
@@ -614,6 +614,8 @@ packet data at a variable offset
 .Pf ( Dv BPF_IND ) ,
 the packet length
 .Pf ( Dv BPF_LEN ) ,
+a random number
+.Pf ( Dv BPF_BPF ) ,
 or a word in the scratch memory store
 .Pf ( Dv BPF_MEM ) .
 For
@@ -673,6 +675,12 @@ A <- P[X+k:1]
 .Xc
 .Sm on
 A <- len
+.Sm off
+.It Xo Dv BPF_LD No + Dv BPF_W No +
+.Dv BPF_RND
+.Xc
+.Sm on
+A <- arc4random()
 .Sm off
 .It Dv BPF_LD No + Dv BPF_IMM
 .Sm on
Index: lib/libpcap/bpf_image.c
===================================================================
RCS file: /cvs/src/lib/libpcap/bpf_image.c,v
retrieving revision 1.10
diff -u -p -r1.10 bpf_image.c
--- lib/libpcap/bpf_image.c	3 Jun 2018 10:29:28 -0000	1.10
+++ lib/libpcap/bpf_image.c	16 Jul 2020 07:08:52 -0000
@@ -82,6 +82,11 @@ bpf_image(p, n)
 		fmt = "#pktlen";
 		break;
 
+	case BPF_LD|BPF_W|BPF_RND:
+		op = "ld";
+		fmt = "#random";
+		break;
+
 	case BPF_LD|BPF_W|BPF_IND:
 		op = "ld";
 		fmt = "[x + %d]";
Index: lib/libpcap/gencode.c
===================================================================
RCS file: /cvs/src/lib/libpcap/gencode.c,v
retrieving revision 1.52
diff -u -p -r1.52 gencode.c
--- lib/libpcap/gencode.c	9 Dec 2018 15:07:06 -0000	1.52
+++ lib/libpcap/gencode.c	16 Jul 2020 07:08:52 -0000
@@ -2870,6 +2870,22 @@ gen_loadlen()
 }
 
 struct arth *
+gen_loadrnd()
+{
+	int regno = alloc_reg();
+	struct arth *a = (struct arth *)newchunk(sizeof(*a));
+	struct slist *s;
+
+	s = new_stmt(BPF_LD|BPF_RND);
+	s->next = new_stmt(BPF_ST);
+	s->next->s.k = regno;
+	a->s = s;
+	a->regno = regno;
+
+	return a;
+}
+
+struct arth *
 gen_loadi(val)
 	int val;
 {
Index: lib/libpcap/gencode.h
===================================================================
RCS file: /cvs/src/lib/libpcap/gencode.h,v
retrieving revision 1.19
diff -u -p -r1.19 gencode.h
--- lib/libpcap/gencode.h	9 Dec 2018 15:07:06 -0000	1.19
+++ lib/libpcap/gencode.h	16 Jul 2020 07:08:52 -0000
@@ -155,6 +155,7 @@ struct qual {
 struct arth *gen_loadi(int);
 struct arth *gen_load(int, struct arth *, int);
 struct arth *gen_loadlen(void);
+struct arth *gen_loadrnd(void);
 struct arth *gen_neg(struct arth *);
 struct arth *gen_arth(int, struct arth *, struct arth *);
 
Index: lib/libpcap/grammar.y
===================================================================
RCS file: /cvs/src/lib/libpcap/grammar.y,v
retrieving revision 1.20
diff -u -p -r1.20 grammar.y
--- lib/libpcap/grammar.y	9 Dec 2018 15:07:06 -0000	1.20
+++ lib/libpcap/grammar.y	16 Jul 2020 07:08:52 -0000
@@ -113,7 +113,7 @@ pcap_parse()
 %token	GEQ LEQ NEQ
 %token	ID EID HID HID6
 %token	LSH RSH
-%token  LEN
+%token  LEN RND
 %token  IPV6 ICMPV6 AH ESP
 %token	VLAN MPLS
 
@@ -425,6 +425,7 @@ narth:	  pname '[' arth ']'		{ $$ = gen_
 	| '-' arth %prec UMINUS		{ $$ = gen_neg($2); }
 	| paren narth ')'		{ $$ = $2; }
 	| LEN				{ $$ = gen_loadlen(); }
+	| RND				{ $$ = gen_loadrnd(); }
 	;
 byteop:	  '&'			{ $$ = '&'; }
 	| '|'			{ $$ = '|'; }
Index: lib/libpcap/optimize.c
===================================================================
RCS file: /cvs/src/lib/libpcap/optimize.c,v
retrieving revision 1.20
diff -u -p -r1.20 optimize.c
--- lib/libpcap/optimize.c	26 Apr 2018 16:22:40 -0000	1.20
+++ lib/libpcap/optimize.c	16 Jul 2020 07:08:52 -0000
@@ -894,6 +894,7 @@ opt_stmt(s, val, alter)
 		break;
 
 	case BPF_LD|BPF_LEN:
+	case BPF_LD|BPF_RND:
 		v = F(s->code, 0L, 0L);
 		vstore(s, &val[A_ATOM], v, alter);
 		break;
Index: lib/libpcap/scanner.l
===================================================================
RCS file: /cvs/src/lib/libpcap/scanner.l,v
retrieving revision 1.26
diff -u -p -r1.26 scanner.l
--- lib/libpcap/scanner.l	9 Dec 2018 15:07:06 -0000	1.26
+++ lib/libpcap/scanner.l	16 Jul 2020 07:08:52 -0000
@@ -220,6 +220,7 @@ or|"||"		return OR;
 not		return '!';
 
 len|length	return LEN;
+rnd|random	return RND;
 inbound		return INBOUND;
 outbound	return OUTBOUND;