Merge branch 'libuuid' of https://github.com/ferivoz/util-linux

* 'libuuid' of https://github.com/ferivoz/util-linux:
  libuuid: check quality of random bytes

include/randutils.h

@@ -11,7 +11,7 @@ extern int rand_get_number(int low_n, int high_n);
 
 /* /dev/urandom based with fallback to rand() */
 extern int random_get_fd(void);
-extern void ul_random_get_bytes(void *buf, size_t nbytes);
+extern int ul_random_get_bytes(void *buf, size_t nbytes);
 extern const char *random_tell_source(void);
 
 #endif

lib/randutils.c

@@ -102,7 +102,12 @@ int random_get_fd(void)
 #define UL_RAND_READ_ATTEMPTS	8
 #define UL_RAND_READ_DELAY	125000	/* microseconds */
 
-void ul_random_get_bytes(void *buf, size_t nbytes)
+/*
+ * Write @nbytes random bytes into @buf.
+ *
+ * Returns 0 for good quality of random bytes or 1 for weak quality.
+ */
+int ul_random_get_bytes(void *buf, size_t nbytes)
 {
 	unsigned char *cp = (unsigned char *)buf;
 	size_t i, n = nbytes;
@@ -118,7 +123,7 @@ void ul_random_get_bytes(void *buf, size_t nbytes)
 		       n -= x;
 		       cp += x;
 		       lose_counter = 0;
-
+		       errno = 0;
 		} else if (errno == ENOSYS) {	/* kernel without getrandom() */
 			break;
 
@@ -177,6 +182,8 @@ void ul_random_get_bytes(void *buf, size_t nbytes)
 		       sizeof(ul_jrand_seed)-sizeof(unsigned short));
 	}
 #endif
+
+	return n != 0;
 }
 
 

libuuid/man/uuid_generate.3

@@ -49,7 +49,10 @@ The
 .B uuid_generate
 function creates a new universally unique identifier (UUID).  The uuid will
 be generated based on high-quality randomness from
+.IR getrandom(2) ,
 .IR /dev/urandom ,
+or
+.IR /dev/random
 if available.  If it is not available, then
 .B uuid_generate
 will use an alternative algorithm which uses the current time, the
@@ -59,8 +62,7 @@ using a pseudo-random generator.
 The
 .B uuid_generate_random
 function forces the use of the all-random UUID format, even if
-a high-quality random number generator (i.e.,
-.IR /dev/urandom )
+a high-quality random number generator
 is not available, in which case a pseudo-random
 generator will be substituted.  Note that the use of a pseudo-random
 generator may compromise the uniqueness of UUIDs

libuuid/src/gen_uuid.c

@@ -499,11 +499,11 @@ int uuid_generate_time_safe(uuid_t out)
 }
 
 
-void __uuid_generate_random(uuid_t out, int *num)
+int __uuid_generate_random(uuid_t out, int *num)
 {
 	uuid_t	buf;
 	struct uuid uu;
-	int i, n;
+	int i, n, r = 0;
 
 	if (!num || !*num)
 		n = 1;
@@ -511,7 +511,8 @@ void __uuid_generate_random(uuid_t out, int *num)
 		n = *num;
 
 	for (i = 0; i < n; i++) {
-		ul_random_get_bytes(buf, sizeof(buf));
+		if (ul_random_get_bytes(buf, sizeof(buf)))
+			r = -1;
 		uuid_unpack(buf, &uu);
 
 		uu.clock_seq = (uu.clock_seq & 0x3FFF) | 0x8000;
@@ -520,6 +521,8 @@ void __uuid_generate_random(uuid_t out, int *num)
 		uuid_pack(&uu, out);
 		out += sizeof(uuid_t);
 	}
+
+	return r;
 }
 
 void uuid_generate_random(uuid_t out)
@@ -531,27 +534,15 @@ void uuid_generate_random(uuid_t out)
 }
 
 /*
- * Check whether good random source (/dev/random or /dev/urandom)
- * is available.
- */
-static int have_random_source(void)
-{
-	return (access("/dev/random", R_OK) == 0 ||
-		access("/dev/urandom", R_OK) == 0);
-}
-
-
-/*
- * This is the generic front-end to uuid_generate_random and
- * uuid_generate_time.  It uses uuid_generate_random only if
- * /dev/urandom is available, since otherwise we won't have
- * high-quality randomness.
+ * This is the generic front-end to __uuid_generate_random and
+ * uuid_generate_time.  It uses __uuid_generate_random output
+ * only if high-quality randomness is available.
  */
 void uuid_generate(uuid_t out)
 {
-	if (have_random_source())
-		uuid_generate_random(out);
-	else
+	int num = 1;
+
+	if (__uuid_generate_random(out, &num))
 		uuid_generate_time(out);
 }
 

libuuid/src/uuidd.h

@@ -49,6 +49,6 @@
 #define UUIDD_MAX_OP			UUIDD_OP_BULK_RANDOM_UUID
 
 extern int __uuid_generate_time(uuid_t out, int *num);
-extern void __uuid_generate_random(uuid_t out, int *num);
+extern int __uuid_generate_random(uuid_t out, int *num);
 
 #endif /* _UUID_UUID_H */