Differential D16760 Diff 46823 lib/libc/gen/getentropy.c

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lib/libc/gen/getentropy.c

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* SUCH DAMAGE.		* SUCH DAMAGE.
*/		*/

#include <sys/cdefs.h>		#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");		__FBSDID("$FreeBSD$");

#include <sys/param.h>		#include <sys/param.h>
#include <sys/random.h>		#include <sys/random.h>
		#include <sys/sysctl.h>

#include <errno.h>		#include <errno.h>
#include <stdlib.h>		#include <stdlib.h>

#include "libc_private.h"		#include "libc_private.h"

		extern int __sysctl(int , u_int, void , size_t , void , size_t);

		static size_t
		arnd_sysctl(u_char *buf, size_t size)
		{
		int mib[2];
		size_t len, done;

		mib[0] = CTL_KERN;
		mib[1] = KERN_ARND;
		done = 0;

		do {
		len = size;
		if (__sysctl(mib, 2, buf, &len, NULL, 0) == -1)
		return (done);
		done += len;
		buf += len;
		size -= len;
		} while (size > 0);

		return (done);
		}

/*		/*
* If a newer libc is accidentally installed on an older kernel, provide high		* If a newer libc is accidentally installed on an older kernel, provide high
* quality random data anyway. The sysctl interface is not as fast and does		* quality random data anyway. The sysctl interface is not as fast and does
* not block by itself, but is provided by even very old kernels.		* not block by itself, but is provided by even very old kernels.
*/		*/
static int		static int
getentropy_fallback(void *buf, size_t buflen)		getentropy_fallback(void *buf, size_t buflen)
{		{
/*		/*
* oldp (buf) == NULL has a special meaning for sysctl that results in		* oldp (buf) == NULL has a special meaning for sysctl that results in
* no EFAULT. For compatibility with the kernel getrandom(2), detect		* no EFAULT. For compatibility with the kernel getrandom(2), detect
* this case and return the appropriate error.		* this case and return the appropriate error.
*/		*/
if (buf == NULL && buflen > 0) {		if (buf == NULL && buflen > 0) {
errno = EFAULT;		errno = EFAULT;
return (-1);		return (-1);
}		}
if (__arc4_sysctl(buf, buflen) != buflen) {		if (arnd_sysctl(buf, buflen) != buflen) {
if (errno == EFAULT)		if (errno == EFAULT)
return (-1);		return (-1);
/*		/*
* This cannot happen. _arc4_sysctl() spins until the random		* This cannot happen. _arc4_sysctl() spins until the random
* device is seeded and then repeatedly reads until the full		* device is seeded and then repeatedly reads until the full
* request is satisfied. The only way for this to return a zero		* request is satisfied. The only way for this to return a zero
* byte or short read is if sysctl(2) on the kern.arandom MIB		* byte or short read is if sysctl(2) on the kern.arandom MIB
* fails. In this case, exceping the user-provided-a-bogus-		* fails. In this case, exceping the user-provided-a-bogus-
Show All 14 Lines	if (buflen > 256) {
return (-1);		return (-1);
}		}

while (buflen > 0) {		while (buflen > 0) {
rd = getrandom(buf, buflen, 0);		rd = getrandom(buf, buflen, 0);
if (rd == -1) {		if (rd == -1) {
if (errno == EINTR)		if (errno == EINTR)
continue;		continue;
else if (errno == ENOSYS)		else if (errno == ENOSYS)
return (getentropy_fallback(buf, buflen));		return (getentropy_fallback(buf, buflen));
		cemUnsubmitted Done Inline Actions Nice catch cem: Nice catch
else		else
return (-1);		return (-1);
}		}

/* This cannot happen. */		/* This cannot happen. */
if (rd == 0)		if (rd == 0)
abort();		abort();

buf = (char *)buf + rd;		buf = (char *)buf + rd;
buflen -= rd;		buflen -= rd;
}		}

return (0);		return (0);
}		}