[PATCH 4.9 138/264] random: group sysctl functions

Greg Kroah-Hartman
2022-06-23T17:17:20Z

From: "Jason A. Donenfeld" <Jason@zx2c4.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@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 35 ++++++++++++++++++++++++++++++-----
1 file changed, 30 insertions(+), 5 deletions(-)

--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1687,9 +1687,34 @@ 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.
*
********************************************************************/

@@ -1697,8 +1722,8 @@ 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];

@@ -1756,14 +1781,14 @@ 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,