Merge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random

Pull random updates from Ted Ts'o:
 "A few /dev/random improvements for the v3.8 merge window."

* tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
  random: Mix cputime from each thread that exits to the pool
  random: prime last_data value per fips requirements
  random: fix debug format strings
  random: make it possible to enable debugging without rebuild

2 files changed, 30 insertions, 13 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index b86eae9b77df..85e81ec1451e 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -399,7 +399,6 @@ static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
 static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
 static struct fasync_struct *fasync;
 
-#if 0
 static bool debug;
 module_param(debug, bool, 0644);
 #define DEBUG_ENT(fmt, arg...) do { \
@@ -410,9 +409,6 @@ module_param(debug, bool, 0644);
                 blocking_pool.entropy_count,\
                 nonblocking_pool.entropy_count,\
                 ## arg); } while (0)
-#else
-#define DEBUG_ENT(fmt, arg...) do {} while (0)
-#endif
 
 /**********************************************************************
  *
@@ -437,6 +433,7 @@ struct entropy_store {
         int entropy_count;
         int entropy_total;
         unsigned int initialized:1;
+        bool last_data_init;
         __u8 last_data[EXTRACT_SIZE];
 };
 
@@ -829,7 +826,7 @@ static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
                 bytes = min_t(int, bytes, sizeof(tmp));
 
                 DEBUG_ENT("going to reseed %s with %d bits "
-                          "(%d of %d requested)\n",
+                          "(%zu of %d requested)\n",
                           r->name, bytes * 8, nbytes * 8, r->entropy_count);
 
                 bytes = extract_entropy(r->pull, tmp, bytes,
@@ -860,7 +857,7 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
         spin_lock_irqsave(&r->lock, flags);
 
         BUG_ON(r->entropy_count > r->poolinfo->POOLBITS);
-        DEBUG_ENT("trying to extract %d bits from %s\n",
+        DEBUG_ENT("trying to extract %zu bits from %s\n",
                   nbytes * 8, r->name);
 
         /* Can we pull enough? */
@@ -882,7 +879,7 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
                 }
         }
 
-        DEBUG_ENT("debiting %d entropy credits from %s%s\n",
+        DEBUG_ENT("debiting %zu entropy credits from %s%s\n",
                   nbytes * 8, r->name, r->limit ? "" : " (unlimited)");
 
         spin_unlock_irqrestore(&r->lock, flags);
@@ -957,6 +954,10 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
         ssize_t ret = 0, i;
         __u8 tmp[EXTRACT_SIZE];
 
+        /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */
+        if (fips_enabled && !r->last_data_init)
+                nbytes += EXTRACT_SIZE;
+
         trace_extract_entropy(r->name, nbytes, r->entropy_count, _RET_IP_);
         xfer_secondary_pool(r, nbytes);
         nbytes = account(r, nbytes, min, reserved);
@@ -967,6 +968,17 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
                 if (fips_enabled) {
                         unsigned long flags;
 
+
+                        /* prime last_data value if need be, per fips 140-2 */
+                        if (!r->last_data_init) {
+                                spin_lock_irqsave(&r->lock, flags);
+                                memcpy(r->last_data, tmp, EXTRACT_SIZE);
+                                r->last_data_init = true;
+                                nbytes -= EXTRACT_SIZE;
+                                spin_unlock_irqrestore(&r->lock, flags);
+                                extract_buf(r, tmp);
+                        }
+
                         spin_lock_irqsave(&r->lock, flags);
                         if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
                                 panic("Hardware RNG duplicated output!\n");
@@ -1086,6 +1098,7 @@ static void init_std_data(struct entropy_store *r)
 
         r->entropy_count = 0;
         r->entropy_total = 0;
+        r->last_data_init = false;
         mix_pool_bytes(r, &now, sizeof(now), NULL);
         for (i = r->poolinfo->POOLBYTES; i > 0; i -= sizeof(rv)) {
                 if (!arch_get_random_long(&rv))
@@ -1142,11 +1155,16 @@ random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
                 if (n > SEC_XFER_SIZE)
                         n = SEC_XFER_SIZE;
 
-                DEBUG_ENT("reading %d bits\n", n*8);
+                DEBUG_ENT("reading %zu bits\n", n*8);
 
                 n = extract_entropy_user(&blocking_pool, buf, n);
 
-                DEBUG_ENT("read got %d bits (%d still needed)\n",
+                if (n < 0) {
+                        retval = n;
+                        break;
+                }
+
+                DEBUG_ENT("read got %zd bits (%zd still needed)\n",
                           n*8, (nbytes-n)*8);
 
                 if (n == 0) {
@@ -1171,10 +1189,6 @@ random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
                         continue;
                 }
 
-                if (n < 0) {
-                        retval = n;
-                        break;
-                }
                 count += n;
                 buf += n;
                 nbytes -= n;
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index d73840271dce..a278cad1d5d6 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -9,6 +9,7 @@
 #include <asm/uaccess.h>
 #include <linux/kernel_stat.h>
 #include <trace/events/timer.h>
+#include <linux/random.h>
 
 /*
  * Called after updating RLIMIT_CPU to run cpu timer and update
@@ -470,6 +471,8 @@ static void cleanup_timers(struct list_head *head,
  */
 void posix_cpu_timers_exit(struct task_struct *tsk)
 {
+        add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
+                                                sizeof(unsigned long long));
         cleanup_timers(tsk->cpu_timers,
                        tsk->utime, tsk->stime, tsk->se.sum_exec_runtime);