linux-kernel - [PATCH 5.4 098/240] random: group sysctl functions

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Date:   Mon, 20 Jun 2022 14:49:59 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Theodore Tso <tytso@....edu>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        "Jason A. Donenfeld" <Jason@...c4.com>
Subject: [PATCH 5.4 098/240] random: group sysctl functions

From: "Jason A. Donenfeld" <Jason@...c4.com>

commit 0deff3c43206c24e746b1410f11125707ad3040e upstream.

This pulls all of the sysctl-focused functions into the sixth labeled
section.

No functional changes.

Cc: Theodore Ts'o <tytso@....edu>
Reviewed-by: Dominik Brodowski <linux@...inikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/char/random.c |   35 ++++++++++++++++++++++++++++++-----
 1 file changed, 30 insertions(+), 5 deletions(-)

--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1688,9 +1688,34 @@ const struct file_operations urandom_fop
 	.llseek = noop_llseek,
 };
 
+
 /********************************************************************
  *
- * Sysctl interface
+ * Sysctl interface.
+ *
+ * These are partly unused legacy knobs with dummy values to not break
+ * userspace and partly still useful things. They are usually accessible
+ * in /proc/sys/kernel/random/ and are as follows:
+ *
+ * - boot_id - a UUID representing the current boot.
+ *
+ * - uuid - a random UUID, different each time the file is read.
+ *
+ * - poolsize - the number of bits of entropy that the input pool can
+ *   hold, tied to the POOL_BITS constant.
+ *
+ * - entropy_avail - the number of bits of entropy currently in the
+ *   input pool. Always <= poolsize.
+ *
+ * - write_wakeup_threshold - the amount of entropy in the input pool
+ *   below which write polls to /dev/random will unblock, requesting
+ *   more entropy, tied to the POOL_MIN_BITS constant. It is writable
+ *   to avoid breaking old userspaces, but writing to it does not
+ *   change any behavior of the RNG.
+ *
+ * - urandom_min_reseed_secs - fixed to the meaningless value "60".
+ *   It is writable to avoid breaking old userspaces, but writing
+ *   to it does not change any behavior of the RNG.
  *
  ********************************************************************/
 
@@ -1698,8 +1723,8 @@ const struct file_operations urandom_fop
 
 #include <linux/sysctl.h>
 
-static int random_min_urandom_seed = 60;
-static int random_write_wakeup_bits = POOL_MIN_BITS;
+static int sysctl_random_min_urandom_seed = 60;
+static int sysctl_random_write_wakeup_bits = POOL_MIN_BITS;
 static int sysctl_poolsize = POOL_BITS;
 static char sysctl_bootid[16];
 
@@ -1757,14 +1782,14 @@ struct ctl_table random_table[] = {
 	},
 	{
 		.procname	= "write_wakeup_threshold",
-		.data		= &random_write_wakeup_bits,
+		.data		= &sysctl_random_write_wakeup_bits,
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
 	{
 		.procname	= "urandom_min_reseed_secs",
-		.data		= &random_min_urandom_seed,
+		.data		= &sysctl_random_min_urandom_seed,
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,