random: Add support for architectural random hooks

commit 63d77173266c1791f1553e9e8ccea65dc87c4485 upstream.

Add support for architecture-specific hooks into the kernel-directed
random number generator interfaces.  This patchset does not use the
architecture random number generator interfaces for the
userspace-directed interfaces (/dev/random and /dev/urandom), thus
eliminating the need to distinguish between them based on a pool
pointer.

Changes in version 3:
- Moved the hooks from extract_entropy() to get_random_bytes().
- Changes the hooks to inlines.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 21 insertions, 2 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index c35a785005b..154eeda26db 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -932,7 +932,21 @@ static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf,
  */
 void get_random_bytes(void *buf, int nbytes)
 {
-        extract_entropy(&nonblocking_pool, buf, nbytes, 0, 0);
+        char *p = buf;
+
+        while (nbytes) {
+                unsigned long v;
+                int chunk = min(nbytes, (int)sizeof(unsigned long));
+
+                if (!arch_get_random_long(&v))
+                        break;
+
+                memcpy(buf, &v, chunk);
+                p += chunk;
+                nbytes -= chunk;
+        }
+
+        extract_entropy(&nonblocking_pool, p, nbytes, 0, 0);
 }
 EXPORT_SYMBOL(get_random_bytes);
 
@@ -1318,9 +1332,14 @@ late_initcall(random_int_secret_init);
 DEFINE_PER_CPU(__u32 [MD5_DIGEST_WORDS], get_random_int_hash);
 unsigned int get_random_int(void)
 {
-        __u32 *hash = get_cpu_var(get_random_int_hash);
+        __u32 *hash;
         unsigned int ret;
 
+        if (arch_get_random_int(&ret))
+                return ret;
+
+        hash = get_cpu_var(get_random_int_hash);
+
         hash[0] += current->pid + jiffies + get_cycles();
         md5_transform(hash, random_int_secret);
         ret = hash[0];