From: Theodore Ts'o <tytso@mit.edu>
Date: Sun, 3 Nov 2013 11:54:51 +0000 (-0500)
Subject: random: printk notifications for urandom pool initialization
X-Git-Tag: firefly_0821_release~176^2~4948^2~3
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=301f0595c0e788edacc3521c4caa90b4e56ffee1;p=firefly-linux-kernel-4.4.55.git

random: printk notifications for urandom pool initialization

Print a notification to the console when the nonblocking pool is
initialized.  Also printk a warning when a process tries reading from
/dev/urandom before it is fully initialized.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 62923138e77a..a19a7a63ec35 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -655,6 +655,9 @@ retry:
 	r->entropy_total += nbits;
 	if (!r->initialized && nbits > 0) {
 		if (r->entropy_total > 128) {
+			if (r == &nonblocking_pool)
+				pr_notice("random: %s pool is initialized\n",
+					  r->name);
 			r->initialized = 1;
 			r->entropy_total = 0;
 		}
@@ -1327,7 +1330,14 @@ random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
 static ssize_t
 urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
 {
-	int ret = extract_entropy_user(&nonblocking_pool, buf, nbytes);
+	int ret;
+
+	if (unlikely(nonblocking_pool.initialized == 0))
+		printk_once(KERN_NOTICE "random: %s urandom read "
+			    "with %d bits of entropy available\n",
+			    current->comm, nonblocking_pool.entropy_total);
+
+	ret = extract_entropy_user(&nonblocking_pool, buf, nbytes);
 
 	trace_urandom_read(8 * nbytes, ENTROPY_BITS(&nonblocking_pool),
 			   ENTROPY_BITS(&input_pool));