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-rw-r--r--drivers/char/random.c84
1 files changed, 43 insertions, 41 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 9d147d456598..b800e5479b7d 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -2016,63 +2016,65 @@ struct ctl_table random_table[] = {
};
#endif /* CONFIG_SYSCTL */
-static u32 random_int_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned;
-
-int random_int_secret_init(void)
-{
- get_random_bytes(random_int_secret, sizeof(random_int_secret));
- return 0;
-}
-
-static DEFINE_PER_CPU(__u32 [MD5_DIGEST_WORDS], get_random_int_hash)
- __aligned(sizeof(unsigned long));
+struct batched_entropy {
+ union {
+ unsigned long entropy_long[CHACHA20_BLOCK_SIZE / sizeof(unsigned long)];
+ unsigned int entropy_int[CHACHA20_BLOCK_SIZE / sizeof(unsigned int)];
+ };
+ unsigned int position;
+};
/*
- * Get a random word for internal kernel use only. Similar to urandom but
- * with the goal of minimal entropy pool depletion. As a result, the random
- * value is not cryptographically secure but for several uses the cost of
- * depleting entropy is too high
+ * Get a random word for internal kernel use only. The quality of the random
+ * number is either as good as RDRAND or as good as /dev/urandom, with the
+ * goal of being quite fast and not depleting entropy.
*/
-unsigned int get_random_int(void)
+static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_long);
+unsigned long get_random_long(void)
{
- __u32 *hash;
- unsigned int ret;
+ unsigned long ret;
+ struct batched_entropy *batch;
- if (arch_get_random_int(&ret))
+ if (arch_get_random_long(&ret))
return ret;
- hash = get_cpu_var(get_random_int_hash);
-
- hash[0] += current->pid + jiffies + random_get_entropy();
- md5_transform(hash, random_int_secret);
- ret = hash[0];
- put_cpu_var(get_random_int_hash);
-
+ batch = &get_cpu_var(batched_entropy_long);
+ if (batch->position % ARRAY_SIZE(batch->entropy_long) == 0) {
+ extract_crng((u8 *)batch->entropy_long);
+ batch->position = 0;
+ }
+ ret = batch->entropy_long[batch->position++];
+ put_cpu_var(batched_entropy_long);
return ret;
}
-EXPORT_SYMBOL(get_random_int);
+EXPORT_SYMBOL(get_random_long);
-/*
- * Same as get_random_int(), but returns unsigned long.
- */
-unsigned long get_random_long(void)
+#if BITS_PER_LONG == 32
+unsigned int get_random_int(void)
{
- __u32 *hash;
- unsigned long ret;
+ return get_random_long();
+}
+#else
+static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_int);
+unsigned int get_random_int(void)
+{
+ unsigned int ret;
+ struct batched_entropy *batch;
- if (arch_get_random_long(&ret))
+ if (arch_get_random_int(&ret))
return ret;
- hash = get_cpu_var(get_random_int_hash);
-
- hash[0] += current->pid + jiffies + random_get_entropy();
- md5_transform(hash, random_int_secret);
- ret = *(unsigned long *)hash;
- put_cpu_var(get_random_int_hash);
-
+ batch = &get_cpu_var(batched_entropy_int);
+ if (batch->position % ARRAY_SIZE(batch->entropy_int) == 0) {
+ extract_crng((u8 *)batch->entropy_int);
+ batch->position = 0;
+ }
+ ret = batch->entropy_int[batch->position++];
+ put_cpu_var(batched_entropy_int);
return ret;
}
-EXPORT_SYMBOL(get_random_long);
+#endif
+EXPORT_SYMBOL(get_random_int);
/**
* randomize_page - Generate a random, page aligned address