Attachment 189567 Details for Bug 182610 – patch to make userspace arc4random fork safe

[patch] patch to make userspace arc4random fork safe

arc4random-fork-safety.patch (text/plain), 1.83 KB, created by Jan Kokemüller on 2018-01-09 19:06:56 UTC

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Creator: Jan Kokemüller

Created: 2018-01-09 19:06:56 UTC

Size: 1.83 KB

patch

obsolete

>diff --git a/lib/libc/gen/arc4random.c b/lib/libc/gen/arc4random.c
>index 1c4d6eebe5fe..4294de02f47e 100644
>--- a/lib/libc/gen/arc4random.c
>+++ b/lib/libc/gen/arc4random.c
>@@ -37,6 +37,7 @@ __FBSDID("$FreeBSD$");
> #include <limits.h>
> #include <stdlib.h>
> #include <unistd.h>
>+#include <sys/mman.h>
> #include <sys/param.h>
> #include <sys/sysctl.h>
> #include <sys/time.h>
>@@ -76,7 +77,7 @@ static pthread_mutex_t	arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;
> static int rs_initialized;
> static struct arc4_stream rs;
> static pid_t arc4_stir_pid;
>-static int arc4_count;
>+static int* arc4_count;
> 
> extern int __sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp,
>     void *newp, size_t newlen);
>@@ -89,6 +90,12 @@ arc4_init(void)
> {
> 	int     n;
> 
>+	if ((arc4_count = mmap(NULL, sizeof(int), PROT_READ|PROT_WRITE,
>+	    MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED)
>+		abort();
>+	if (minherit(arc4_count, sizeof(int), INHERIT_ZERO) == -1)
>+		abort();
>+
> 	for (n = 0; n < 256; n++)
> 		rs.s[n] = n;
> 	rs.i = 0;
>@@ -162,7 +169,7 @@ arc4_stir(void)
> 	 */
> 	for (i = 0; i < 3072; i++)
> 		(void)arc4_getbyte();
>-	arc4_count = 1600000;
>+	*arc4_count = 1600000;
> }
> 
> static void
>@@ -170,7 +177,8 @@ arc4_stir_if_needed(void)
> {
> 	pid_t pid = getpid();
> 
>-	if (arc4_count <= 0 || !rs_initialized || arc4_stir_pid != pid) {
>+	if (arc4_count == NULL || *arc4_count <= 0 || !rs_initialized ||
>+	    arc4_stir_pid != pid) {
> 		arc4_stir_pid = pid;
> 		arc4_stir();
> 	}
>@@ -224,7 +232,8 @@ arc4random(void)
> {
> 	u_int32_t val;
> 	_ARC4_LOCK();
>-	arc4_count -= 4;
>+	if (arc4_count)
>+		*arc4_count -= 4;
> 	arc4_stir_if_needed();
> 	val = arc4_getword();
> 	_ARC4_UNLOCK();
>@@ -238,7 +247,7 @@ arc4random_buf(void *_buf, size_t n)
> 	_ARC4_LOCK();
> 	arc4_stir_if_needed();
> 	while (n--) {
>-		if (--arc4_count <= 0)
>+		if (--*arc4_count <= 0)
> 			arc4_stir();
> 		buf[n] = arc4_getbyte();
> 	}

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