random: Add support for architectural random hooks

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>

2 files changed, 35 insertions, 3 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index d4ddeba56682..bb587127fb9d 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);
 
@@ -1635,8 +1649,13 @@ DEFINE_PER_CPU(__u32 [4], get_random_int_hash);
 unsigned int get_random_int(void)
 {
         struct keydata *keyptr;
-        __u32 *hash = get_cpu_var(get_random_int_hash);
-        int ret;
+        __u32 *hash;
+        unsigned int ret;
+
+        if (arch_get_random_int(&ret))
+                return ret;
+
+        hash = get_cpu_var(get_random_int_hash);
 
         keyptr = get_keyptr();
         hash[0] += current->pid + jiffies + get_cycles();
diff --git a/include/linux/random.h b/include/linux/random.h
index fb7ab9de5f36..079cbba39a28 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -102,6 +102,19 @@ static inline void prandom32_seed(struct rnd_state *state, u64 seed)
         state->s3 = __seed(i, 15);
 }
 
+#ifdef CONFIG_ARCH_RANDOM
+# include <asm/archrandom.h>
+#else
+static inline int arch_get_random_long(unsigned long *v)
+{
+        return 0;
+}
+static inline int arch_get_random_int(unsigned int *v)
+{
+        return 0;
+}
+#endif
+
 #endif /* __KERNEL___ */
 
 #endif /* _LINUX_RANDOM_H */