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Use arc4random_uniform() to avoid "modulo bias"

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Remove pw_getrand() unneded now: arc4random_uniform() is stronger then
pw_getrand()'s MD5 tricks (inactive) and its active version, mixing
arc4random() bytes in one, not make things better at all.
This commit is contained in:
Andrey A. Chernov 2008-08-16 15:41:03 +00:00
parent 48d48eb980
commit f70f5c2077
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=181785
1 changed files with 2 additions and 55 deletions
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57
usr.sbin/pw/pw_user.c
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@ -43,9 +43,6 @@ static const char rcsid[] =
#include <unistd.h>
#include <utmp.h>
#include <login_cap.h>
#if defined(USE_MD5RAND)
#include <md5.h>
#endif
#include "pw.h"
#include "bitmap.h"
@ -1045,74 +1042,24 @@ pw_pwcrypt(char *password)
* Calculate a salt value
*/
for (i = 0; i < SALTSIZE; i++)
salt[i] = chars[arc4random() % (sizeof(chars) - 1)];
salt[i] = chars[arc4random_uniform(sizeof(chars) - 1)];
salt[SALTSIZE] = '\0';
return strcpy(buf, crypt(password, salt));
}
#if defined(USE_MD5RAND)
u_char *
pw_getrand(u_char *buf, int len) /* cryptographically secure rng */
{
int i;
for (i=0;i<len;i+=16) {
u_char ubuf[16];
MD5_CTX md5_ctx;
struct timeval tv, tvo;
struct rusage ru;
int n=0;
int t;
MD5Init (&md5_ctx);
t=getpid();
MD5Update (&md5_ctx, (u_char*)&t, sizeof t);
t=getppid();
MD5Update (&md5_ctx, (u_char*)&t, sizeof t);
gettimeofday (&tvo, NULL);
do {
getrusage (RUSAGE_SELF, &ru);
MD5Update (&md5_ctx, (u_char*)&ru, sizeof ru);
gettimeofday (&tv, NULL);
MD5Update (&md5_ctx, (u_char*)&tv, sizeof tv);
} while (n++<20 || tv.tv_usec-tvo.tv_usec<100*1000);
MD5Final (ubuf, &md5_ctx);
memcpy(buf+i, ubuf, MIN(16, len-i));
}
return buf;
}
#else /* Portable version */
static u_char *
pw_getrand(u_char *buf, int len)
{
int i;
for (i = 0; i < len; i++) {
unsigned long val = arc4random();
/* Use all bits in the random value */
buf[i]=(u_char)((val >> 24) ^ (val >> 16) ^ (val >> 8) ^ val);
}
return buf;
}
#endif
static char *
pw_password(struct userconf * cnf, struct cargs * args, char const * user)
{
int i, l;
char pwbuf[32];
u_char rndbuf[sizeof pwbuf];
switch (cnf->default_password) {
case -1: /* Random password */
l = (arc4random() % 8 + 8); /* 8 - 16 chars */
pw_getrand(rndbuf, l);
for (i = 0; i < l; i++)
pwbuf[i] = chars[rndbuf[i] % (sizeof(chars)-1)];
pwbuf[i] = chars[arc4random_uniform(sizeof(chars)-1)];
pwbuf[i] = '\0';
/*