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

Pull random updates from Ted Ts'o:
 "Change get_random_{int,log} to use the CRNG used by /dev/urandom and
  getrandom(2). It's faster and arguably more secure than cut-down MD5
  that we had been using.

  Also do some code cleanup"

* tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
  random: move random_min_urandom_seed into CONFIG_SYSCTL ifdef block
  random: convert get_random_int/long into get_random_u32/u64
  random: use chacha20 for get_random_int/long
  random: fix comment for unused random_min_urandom_seed
  random: remove variable limit
  random: remove stale urandom_init_wait
  random: remove stale maybe_reseed_primary_crng

3 files changed, 65 insertions, 83 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 1ef26403bcc8..0ab024918907 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -313,13 +313,6 @@ static int random_read_wakeup_bits = 64;
 static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS;
 
 /*
- * The minimum number of seconds between urandom pool reseeding.  We
- * do this to limit the amount of entropy that can be drained from the
- * input pool even if there are heavy demands on /dev/urandom.
- */
-static int random_min_urandom_seed = 60;
-
-/*
  * Originally, we used a primitive polynomial of degree .poolwords
  * over GF(2).  The taps for various sizes are defined below.  They
  * were chosen to be evenly spaced except for the last tap, which is 1
@@ -409,7 +402,6 @@ static struct poolinfo {
  */
 static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
 static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
-static DECLARE_WAIT_QUEUE_HEAD(urandom_init_wait);
 static struct fasync_struct *fasync;
 
 static DEFINE_SPINLOCK(random_ready_list_lock);
@@ -467,7 +459,6 @@ struct entropy_store {
         int entropy_count;
         int entropy_total;
         unsigned int initialized:1;
-        unsigned int limit:1;
         unsigned int last_data_init:1;
         __u8 last_data[EXTRACT_SIZE];
 };
@@ -485,7 +476,6 @@ static __u32 blocking_pool_data[OUTPUT_POOL_WORDS] __latent_entropy;
 static struct entropy_store input_pool = {
         .poolinfo = &poolinfo_table[0],
         .name = "input",
-        .limit = 1,
         .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
         .pool = input_pool_data
 };
@@ -493,7 +483,6 @@ static struct entropy_store input_pool = {
 static struct entropy_store blocking_pool = {
         .poolinfo = &poolinfo_table[1],
         .name = "blocking",
-        .limit = 1,
         .pull = &input_pool,
         .lock = __SPIN_LOCK_UNLOCKED(blocking_pool.lock),
         .pool = blocking_pool_data,
@@ -855,13 +844,6 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
         spin_unlock_irqrestore(&primary_crng.lock, flags);
 }
 
-static inline void maybe_reseed_primary_crng(void)
-{
-        if (crng_init > 2 &&
-            time_after(jiffies, primary_crng.init_time + CRNG_RESEED_INTERVAL))
-                crng_reseed(&primary_crng, &input_pool);
-}
-
 static inline void crng_wait_ready(void)
 {
         wait_event_interruptible(crng_init_wait, crng_ready());
@@ -1220,15 +1202,6 @@ static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
             r->entropy_count > r->poolinfo->poolfracbits)
                 return;
 
-        if (r->limit == 0 && random_min_urandom_seed) {
-                unsigned long now = jiffies;
-
-                if (time_before(now,
-                                r->last_pulled + random_min_urandom_seed * HZ))
-                        return;
-                r->last_pulled = now;
-        }
-
         _xfer_secondary_pool(r, nbytes);
 }
 
@@ -1236,8 +1209,6 @@ static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
 {
         __u32   tmp[OUTPUT_POOL_WORDS];
 
-        /* For /dev/random's pool, always leave two wakeups' worth */
-        int rsvd_bytes = r->limit ? 0 : random_read_wakeup_bits / 4;
         int bytes = nbytes;
 
         /* pull at least as much as a wakeup */
@@ -1248,7 +1219,7 @@ static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
         trace_xfer_secondary_pool(r->name, bytes * 8, nbytes * 8,
                                   ENTROPY_BITS(r), ENTROPY_BITS(r->pull));
         bytes = extract_entropy(r->pull, tmp, bytes,
-                                random_read_wakeup_bits / 8, rsvd_bytes);
+                                random_read_wakeup_bits / 8, 0);
         mix_pool_bytes(r, tmp, bytes);
         credit_entropy_bits(r, bytes*8);
 }
@@ -1276,7 +1247,7 @@ static void push_to_pool(struct work_struct *work)
 static size_t account(struct entropy_store *r, size_t nbytes, int min,
                       int reserved)
 {
-        int entropy_count, orig;
+        int entropy_count, orig, have_bytes;
         size_t ibytes, nfrac;
 
         BUG_ON(r->entropy_count > r->poolinfo->poolfracbits);
@@ -1285,14 +1256,12 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
 retry:
         entropy_count = orig = ACCESS_ONCE(r->entropy_count);
         ibytes = nbytes;
-        /* If limited, never pull more than available */
-        if (r->limit) {
-                int have_bytes = entropy_count >> (ENTROPY_SHIFT + 3);
+        /* never pull more than available */
+        have_bytes = entropy_count >> (ENTROPY_SHIFT + 3);
 
-                if ((have_bytes -= reserved) < 0)
-                        have_bytes = 0;
-                ibytes = min_t(size_t, ibytes, have_bytes);
-        }
+        if ((have_bytes -= reserved) < 0)
+                have_bytes = 0;
+        ibytes = min_t(size_t, ibytes, have_bytes);
         if (ibytes < min)
                 ibytes = 0;
 
@@ -1912,6 +1881,7 @@ SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
 static int min_read_thresh = 8, min_write_thresh;
 static int max_read_thresh = OUTPUT_POOL_WORDS * 32;
 static int max_write_thresh = INPUT_POOL_WORDS * 32;
+static int random_min_urandom_seed = 60;
 static char sysctl_bootid[16];
 
 /*
@@ -2042,63 +2012,64 @@ 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 {
+                u64 entropy_u64[CHACHA20_BLOCK_SIZE / sizeof(u64)];
+                u32 entropy_u32[CHACHA20_BLOCK_SIZE / sizeof(u32)];
+        };
+        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_u64);
+u64 get_random_u64(void)
 {
-        __u32 *hash;
-        unsigned int ret;
+        u64 ret;
+        struct batched_entropy *batch;
 
-        if (arch_get_random_int(&ret))
+#if BITS_PER_LONG == 64
+        if (arch_get_random_long((unsigned long *)&ret))
                 return ret;
+#else
+        if (arch_get_random_long((unsigned long *)&ret) &&
+            arch_get_random_long((unsigned long *)&ret + 1))
+            return ret;
+#endif
 
-        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_u64);
+        if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) {
+                extract_crng((u8 *)batch->entropy_u64);
+                batch->position = 0;
+        }
+        ret = batch->entropy_u64[batch->position++];
+        put_cpu_var(batched_entropy_u64);
         return ret;
 }
-EXPORT_SYMBOL(get_random_int);
+EXPORT_SYMBOL(get_random_u64);
 
-/*
- * Same as get_random_int(), but returns unsigned long.
- */
-unsigned long get_random_long(void)
+static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32);
+u32 get_random_u32(void)
 {
-        __u32 *hash;
-        unsigned long ret;
+        u32 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_u32);
+        if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) {
+                extract_crng((u8 *)batch->entropy_u32);
+                batch->position = 0;
+        }
+        ret = batch->entropy_u32[batch->position++];
+        put_cpu_var(batched_entropy_u32);
         return ret;
 }
-EXPORT_SYMBOL(get_random_long);
+EXPORT_SYMBOL(get_random_u32);
 
 /**
  * randomize_page - Generate a random, page aligned address
diff --git a/include/linux/random.h b/include/linux/random.h
index 7bd2403e4fef..ed5c3838780d 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -37,14 +37,26 @@ extern void get_random_bytes(void *buf, int nbytes);
 extern int add_random_ready_callback(struct random_ready_callback *rdy);
 extern void del_random_ready_callback(struct random_ready_callback *rdy);
 extern void get_random_bytes_arch(void *buf, int nbytes);
-extern int random_int_secret_init(void);
 
 #ifndef MODULE
 extern const struct file_operations random_fops, urandom_fops;
 #endif
 
-unsigned int get_random_int(void);
-unsigned long get_random_long(void);
+u32 get_random_u32(void);
+u64 get_random_u64(void);
+static inline unsigned int get_random_int(void)
+{
+        return get_random_u32();
+}
+static inline unsigned long get_random_long(void)
+{
+#if BITS_PER_LONG == 64
+        return get_random_u64();
+#else
+        return get_random_u32();
+#endif
+}
+
 unsigned long randomize_page(unsigned long start, unsigned long range);
 
 u32 prandom_u32(void);
diff --git a/init/main.c b/init/main.c
index eae2f15657c6..f9c9d9948203 100644
--- a/init/main.c
+++ b/init/main.c
@@ -882,7 +882,6 @@ static void __init do_basic_setup(void)
         do_ctors();
         usermodehelper_enable();
         do_initcalls();
-        random_int_secret_init();
 }
 
 static void __init do_pre_smp_initcalls(void)