- make arc4random*() functions thread safe. Use a custom spinlock function

instead of the generic pthread macros since free(3) uses __arc4_getbyte()
when freeing small sized allocations and the generic pthread macros call
malloc(3).
- eliminate passing pointers to a static variable with global scope (rs)
for additional code clarity and reduction.
- shlib minor bumps for libc and libpthread due to new functions.
From andreas@ with some bits from me. okay tedu@ marc@ w/some spot
checking from millert@

2 files changed, 69 insertions, 42 deletions

diff --git a/src/lib/libc/crypt/arc4random.c b/src/lib/libc/crypt/arc4random.c
index 35d7953002..8604548f3f 100644
--- a/src/lib/libc/crypt/arc4random.c
+++ b/src/lib/libc/crypt/arc4random.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: arc4random.c,v 1.16 2007/02/12 19:58:47 otto Exp $    */
+/*      $OpenBSD: arc4random.c,v 1.17 2008/01/01 00:43:39 kurt Exp $    */
 
 /*
  * Copyright (c) 1996, David Mazieres <dm@uun.org>
@@ -40,6 +40,7 @@
 #include <sys/param.h>
 #include <sys/time.h>
 #include <sys/sysctl.h>
+#include "thread_private.h"
 
 #ifdef __GNUC__
 #define inline __inline
@@ -58,43 +59,48 @@ static struct arc4_stream rs;
 static pid_t arc4_stir_pid;
 static int arc4_count;
 
-static inline u_int8_t arc4_getbyte(struct arc4_stream *);
+static inline u_int8_t arc4_getbyte(void);
 
 static inline void
-arc4_init(struct arc4_stream *as)
+arc4_init(void)
 {
         int     n;
 
         for (n = 0; n < 256; n++)
-                as->s[n] = n;
-        as->i = 0;
-        as->j = 0;
+                rs.s[n] = n;
+        rs.i = 0;
+        rs.j = 0;
 }
 
 static inline void
-arc4_addrandom(struct arc4_stream *as, u_char *dat, int datlen)
+arc4_addrandom(u_char *dat, int datlen)
 {
         int     n;
         u_int8_t si;
 
-        as->i--;
+        rs.i--;
         for (n = 0; n < 256; n++) {
-                as->i = (as->i + 1);
-                si = as->s[as->i];
-                as->j = (as->j + si + dat[n % datlen]);
-                as->s[as->i] = as->s[as->j];
-                as->s[as->j] = si;
+                rs.i = (rs.i + 1);
+                si = rs.s[rs.i];
+                rs.j = (rs.j + si + dat[n % datlen]);
+                rs.s[rs.i] = rs.s[rs.j];
+                rs.s[rs.j] = si;
         }
-        as->j = as->i;
+        rs.j = rs.i;
 }
 
 static void
-arc4_stir(struct arc4_stream *as)
+arc4_stir(void)
 {
         int     i, mib[2];
         size_t  len;
         u_char rnd[128];
 
+        if (!rs_initialized) {
+                arc4_init();
+                rs_initialized = 1;
+        }
+
         mib[0] = CTL_KERN;
         mib[1] = KERN_ARND;
 
@@ -102,75 +108,84 @@ arc4_stir(struct arc4_stream *as)
         sysctl(mib, 2, rnd, &len, NULL, 0);
 
         arc4_stir_pid = getpid();
-        arc4_addrandom(as, rnd, sizeof(rnd));
+        arc4_addrandom(rnd, sizeof(rnd));
 
         /*
          * Discard early keystream, as per recommendations in:
          * http://www.wisdom.weizmann.ac.il/~itsik/RC4/Papers/Rc4_ksa.ps
          */
         for (i = 0; i < 256; i++)
-                (void)arc4_getbyte(as);
+                (void)arc4_getbyte();
         arc4_count = 1600000;
 }
 
 static inline u_int8_t
-arc4_getbyte(struct arc4_stream *as)
+arc4_getbyte(void)
 {
         u_int8_t si, sj;
 
-        as->i = (as->i + 1);
-        si = as->s[as->i];
-        as->j = (as->j + si);
-        sj = as->s[as->j];
-        as->s[as->i] = sj;
-        as->s[as->j] = si;
-        return (as->s[(si + sj) & 0xff]);
+        rs.i = (rs.i + 1);
+        si = rs.s[rs.i];
+        rs.j = (rs.j + si);
+        sj = rs.s[rs.j];
+        rs.s[rs.i] = sj;
+        rs.s[rs.j] = si;
+        return (rs.s[(si + sj) & 0xff]);
 }
 
 u_int8_t
 __arc4_getbyte(void)
 {
+        u_int8_t val;
+
+        _ARC4_LOCK();
         if (--arc4_count == 0 || !rs_initialized)
-                arc4random_stir();
-        return arc4_getbyte(&rs);
+                arc4_stir();
+        val = arc4_getbyte();
+        _ARC4_UNLOCK();
+        return val;
 }
 
 static inline u_int32_t
-arc4_getword(struct arc4_stream *as)
+arc4_getword(void)
 {
         u_int32_t val;
-        val = arc4_getbyte(as) << 24;
-        val |= arc4_getbyte(as) << 16;
-        val |= arc4_getbyte(as) << 8;
-        val |= arc4_getbyte(as);
+        val = arc4_getbyte() << 24;
+        val |= arc4_getbyte() << 16;
+        val |= arc4_getbyte() << 8;
+        val |= arc4_getbyte();
         return val;
 }
 
 void
 arc4random_stir(void)
 {
-        if (!rs_initialized) {
-                arc4_init(&rs);
-                rs_initialized = 1;
-        }
-        arc4_stir(&rs);
+        _ARC4_LOCK();
+        arc4_stir();
+        _ARC4_UNLOCK();
 }
 
 void
 arc4random_addrandom(u_char *dat, int datlen)
 {
+        _ARC4_LOCK();
         if (!rs_initialized)
-                arc4random_stir();
-        arc4_addrandom(&rs, dat, datlen);
+                arc4_stir();
+        arc4_addrandom(dat, datlen);
+        _ARC4_UNLOCK();
 }
 
 u_int32_t
 arc4random(void)
 {
+        u_int32_t val;
+        _ARC4_LOCK();
         arc4_count -= 4;
         if (arc4_count <= 0 || !rs_initialized || arc4_stir_pid != getpid())
-                arc4random_stir();
-        return arc4_getword(&rs);
+                arc4_stir();
+        val = arc4_getword();
+        _ARC4_UNLOCK();
+        return val;
 }
 
 #if 0
diff --git a/src/lib/libc/include/thread_private.h b/src/lib/libc/include/thread_private.h
index 146f0b0a01..f55880f7ba 100644
--- a/src/lib/libc/include/thread_private.h
+++ b/src/lib/libc/include/thread_private.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: thread_private.h,v 1.21 2007/11/19 02:54:19 kurt Exp $ */
+/* $OpenBSD: thread_private.h,v 1.22 2008/01/01 00:43:39 kurt Exp $ */
 
 /* PUBLIC DOMAIN: No Rights Reserved. Marco S Hyman <marc@snafu.org> */
 
@@ -150,4 +150,16 @@ void	_thread_atexit_unlock(void);
                                                 _thread_atexit_unlock();\
                                 } while (0)
 
+void    _thread_arc4_lock(void);
+void    _thread_arc4_unlock(void);
+
+#define _ARC4_LOCK()            do {                                    \
+                                        if (__isthreaded)               \
+                                                _thread_arc4_lock();    \
+                                } while (0)
+#define _ARC4_UNLOCK()          do {                                    \
+                                        if (__isthreaded)               \
+                                                _thread_arc4_unlock();\
+                                } while (0)
+
 #endif /* _THREAD_PRIVATE_H_ */