#

# Replace arc4random* calls with FIPS compliant implementation in FIPS mode.

#

# Once libc:arc4random* are FIPS compliant (20816957), this patch will be

# dropped.

#

# This is a temporary patch and is not intented for upstream contribution.

#

diff -pur old/misc.c new/misc.c

--- old/misc.c

+++ new/misc.c

@@ -1164,3 +1164,87 @@ sock_set_v6only(int s)

 		error("setsockopt IPV6_V6ONLY: %s", strerror(errno));

 #endif

 }

+

+#ifdef ENABLE_OPENSSL_FIPS

+/* cancel arc4random* -> fips_arc4random* defines from misc.h */

+#undef	arc4random

+#undef	arc4random_buf

+#undef	arc4random_stir

+#undef	arc4random_uniform

+

+/* FIPS compliant alternative for arc4random */

+static uint32_t

+fips_arc4random_impl()

+{

+	unsigned int r = 0;

+

+	if (RAND_bytes((unsigned char *)&r, sizeof (r)) <= 0) {

+		fatal("RAND_bytes() failed. Aborting the process");

+	}

+

+	return (r);

+}

+

+uint32_t

+fips_arc4random()

+{

+	if (!ssh_FIPS_mode())

+		return arc4random();

+	else

+		return fips_arc4random_impl();

+}

+

+/* implementation taken from openbsd-compat/arc4random.c */

+void

+fips_arc4random_buf(void *_buf, size_t n)

+{

+	size_t i;

+	uint32_t r = 0;

+	char *buf = (char *)_buf;

+

+	if (!ssh_FIPS_mode())

+		return arc4random_buf(_buf, n);

+

+	for (i = 0; i < n; i++) {

+		if (i % 4 == 0)

+			r = fips_arc4random_impl();

+		buf[i] = r & 0xff;

+		r >>= 8;

+	}

+	explicit_bzero(&r, sizeof(r));

+}

+

+void

+fips_arc4random_stir(void)

+{

+	if (!ssh_FIPS_mode())

+		return arc4random_stir();

+}

+

+/* implementation taken from openbsd-compat/arc4random.c */

+uint32_t

+fips_arc4random_uniform(uint32_t upper_bound)

+{

+	uint32_t r, min;

+

+	if (upper_bound < 2)

+		return 0;

+

+	/* 2**32 % x == (2**32 - x) % x */

+	min = -upper_bound % upper_bound;

+

+	/*

+	 * This could theoretically loop forever but each retry has

+	 * p > 0.5 (worst case, usually far better) of selecting a

+	 * number inside the range we need, so it should rarely need

+	 * to re-roll.

+	 */

+	for (;;) {

+		r = fips_arc4random_impl();

+		if (r >= min)

+			break;

+	}

+

+	return r % upper_bound;

+}

+#endif /* ENABLE_OPENSSL_FIPS */

diff -pur old/misc.h new/misc.h

--- old/misc.h

+++ new/misc.h

@@ -140,4 +140,16 @@ char	*read_passphrase(const char *, int)

 int	 ask_permission(const char *, ...) __attribute__((format(printf, 1, 2)));

 int	 read_keyfile_line(FILE *, const char *, char *, size_t, u_long *);

+#ifdef ENABLE_OPENSSL_FIPS

+/* arc4random* FIPS alternatives */

+uint32_t fips_arc4random(void);

+void	 fips_arc4random_buf(void *, size_t);

+void	 fips_arc4random_stir(void);

+uint32_t fips_arc4random_uniform(uint32_t upper_bound);

+#define	arc4random fips_arc4random

+#define	arc4random_buf fips_arc4random_buf

+#define	arc4random_stir fips_arc4random_stir

+#define	arc4random_uniform fips_arc4random_uniform

+#endif /* ENABLE_OPENSSL_FIPS */

+

 #endif /* _MISC_H */