From owner-freebsd-audit Sat Nov 27 22:22:32 1999 Delivered-To: freebsd-audit@freebsd.org Received: from spirit.jaded.net (dialin2899.toronto.globalserve.net [209.90.160.135]) by hub.freebsd.org (Postfix) with ESMTP id B39C315027 for ; Sat, 27 Nov 1999 22:22:15 -0800 (PST) (envelope-from dan@spirit.jaded.net) Received: (from dan@localhost) by spirit.jaded.net (8.9.3/8.9.3) id BAA24411 for freebsd-audit@freebsd.org; Sun, 28 Nov 1999 01:24:20 -0500 (EST) Date: Sun, 28 Nov 1999 01:24:20 -0500 From: Dan Moschuk To: freebsd-audit@freebsd.org Subject: Last random PID patch before commit Message-ID: <19991128012420.A48334@spirit.jaded.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0i Sender: owner-freebsd-audit@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Here's the last functionality change before I commit this. I doubt that using random() to generate the key used to shuffle the ARC4 algorithm is the absolute best way of doing it, but, It Works(tm). The other option I looked at was read_random(), but I'm not 100% certain that it will have built up sufficient entropy by the time the code is called (usually at bootup). At any rate... Index: i386/conf/files.i386 =================================================================== RCS file: /home/ncvs/src/sys/i386/conf/files.i386,v retrieving revision 1.281 diff -u -r1.281 files.i386 --- files.i386 1999/11/25 20:45:45 1.281 +++ files.i386 1999/11/28 06:04:52 @@ -373,6 +373,7 @@ isa/syscons_isa.c optional sc isa/vga_isa.c optional vga kern/subr_diskmbr.c standard +libkern/arc4random.c standard libkern/bcd.c standard libkern/divdi3.c standard libkern/index.c standard Index: kern/kern_fork.c =================================================================== RCS file: /home/ncvs/src/sys/kern/kern_fork.c,v retrieving revision 1.69 diff -u -r1.69 kern_fork.c --- kern_fork.c 1999/11/19 21:29:03 1.69 +++ kern_fork.c 1999/11/28 06:05:02 @@ -142,6 +142,9 @@ int nprocs = 1; /* process 0 */ static int nextpid = 0; +static int randompid = 0; +SYSCTL_INT(_kern, OID_AUTO, randompid, CTLFLAG_RW, &randompid, 0, ""); + int fork1(p1, flags, procp) struct proc *p1; @@ -262,8 +265,8 @@ * restart somewhat above 0, as the low-numbered procs * tend to include daemons that don't exit. */ - if (nextpid >= PID_MAX) { - nextpid = 100; + if (nextpid >= PID_MAX || randompid) { + nextpid = (randompid) ? arc4random() % PID_MAX : 100; pidchecked = 0; } if (nextpid >= pidchecked) { Index: libkern/arc4random.c =================================================================== RCS file: arc4random.c diff -N arc4random.c --- /dev/null Sat Nov 27 21:16:45 1999 +++ arc4random.c Sat Nov 27 22:05:05 1999 @@ -0,0 +1,95 @@ +/*- + * THE BEER-WARE LICENSE + * + * wrote this file. As long as you retain this notice you + * can do whatever you want with this stuff. If we meet some day, and you + * think this stuff is worth it, you can buy me a beer in return. + * + * Dan Moschuk + * + * $FreeBSD$ + */ + +#include +#include + +static u_int8_t arc4_i, arc4_j; +static int arc4_initialized = 0; +static u_int8_t arc4_sbox[256]; + +static void arc4_init __P((void)); +static u_int8_t arc4_randbyte __P((void)); +static __inline void arc4_swap __P((u_int8_t *, u_int8_t *)); + +static __inline void +arc4_swap(a, b) + u_int8_t *a; + u_int8_t *b; +{ + u_int8_t c; + + c = *a; + *a = *b; + *b = c; +} + +/* + * Initialize our S-box to its beginning defaults. + */ +static void +arc4_init(void) +{ + struct timespec ts; + u_int8_t key[256]; + int n; + + for (n = 0; n < 256; n++) + arc4_sbox[n] = (u_int8_t) n; + + nanotime(&ts); + srandom(ts.tv_sec ^ ts.tv_nsec); + for (n = 0; n < 256; n++) + key[n] = random() % 256; + + arc4_i = arc4_j = 0; + for (n = 0; n < 256; n++) + { + arc4_j = (arc4_j + arc4_sbox[n] + key[n]); + arc4_swap(&arc4_sbox[n], &arc4_sbox[arc4_j]); + } + arc4_initialized = 1; +} + +/* + * Generate a random byte. + */ +static u_int8_t +arc4_randbyte(void) +{ + u_int8_t arc4_t; + + arc4_i = (arc4_i + 1) % 256; + arc4_j = (arc4_j + arc4_sbox[arc4_i]) % 256; + + arc4_swap(&arc4_sbox[arc4_i], &arc4_sbox[arc4_j]); + + arc4_t = (arc4_sbox[arc4_i] + arc4_sbox[arc4_j]) % 256; + return arc4_sbox[arc4_t]; +} + +u_int32_t +arc4random(void) +{ + u_int32_t ret; + + /* Initialize array if needed. */ + if (!arc4_initialized) + arc4_init(); + + ret = arc4_randbyte(); + ret |= arc4_randbyte() << 8; + ret |= arc4_randbyte() << 16; + ret |= arc4_randbyte() << 24; + + return ret; +} Index: sys/libkern.h =================================================================== RCS file: /home/ncvs/src/sys/sys/libkern.h,v retrieving revision 1.18 diff -u -r1.18 libkern.h --- libkern.h 1999/11/21 04:26:47 1.18 +++ libkern.h 1999/11/28 06:05:29 @@ -61,6 +61,7 @@ static __inline u_long ulmin(u_long a, u_long b) { return (a < b ? a : b); } /* Prototypes for non-quad routines. */ +u_int32_t arc4random __P((void)); int bcmp __P((const void *, const void *, size_t)); #ifndef HAVE_INLINE_FFS int ffs __P((int)); -- Dan Moschuk (TFreak!dan@freebsd.org) "Cure for global warming: One giant heatsink and dual fans!" 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