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>
[PG: .34 already had "unsigned int ret" in get_random_int, so the
 diffstat here is slightly smaller than that of 63d7717. ]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 1e07bbe393a794aa74e8b87c11d1e24571385917..6da0696c963078a296bd4189a1486578a0bbba53 100644 (file)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -925,7 +925,21 @@ 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);
 
@@ -1309,9 +1323,14 @@ 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];

diff --git a/include/linux/random.h b/include/linux/random.h
index 29480462bdfb8c956b64487e1f72c40c55f0d48b..0bf293697f09e2840415f6a241c1473cfb1fd707 100644 (file)
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -63,6 +63,19 @@ unsigned long randomize_range(unsigned long start, unsigned long end, unsigned l
 u32 random32(void);
 void srandom32(u32 seed);
 
+#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 */