2 files changed, 46 insertions, 7 deletions

diff --git a/crypto/drbg.c b/crypto/drbg.c
index aca86847ea49..92843488af09 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -1062,13 +1062,18 @@ static void drbg_async_seed(struct work_struct *work)
         LIST_HEAD(seedlist);
         struct drbg_state *drbg = container_of(work, struct drbg_state,
                                                seed_work);
+        int ret;
 
         get_blocking_random_bytes(drbg->seed_buf, drbg->seed_buf_len);
 
         drbg_string_fill(&data, drbg->seed_buf, drbg->seed_buf_len);
         list_add_tail(&data.list, &seedlist);
         mutex_lock(&drbg->drbg_mutex);
-        __drbg_seed(drbg, &seedlist, true);
+        ret = __drbg_seed(drbg, &seedlist, true);
+        if (!ret && drbg->jent) {
+                crypto_free_rng(drbg->jent);
+                drbg->jent = NULL;
+        }
         memzero_explicit(drbg->seed_buf, drbg->seed_buf_len);
         mutex_unlock(&drbg->drbg_mutex);
 }
@@ -1103,10 +1108,24 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
                                  drbg->test_data.len);
                 pr_devel("DRBG: using test entropy\n");
         } else {
-                pr_devel("DRBG: (re)seeding with %zu bytes of entropy\n",
-                         drbg->seed_buf_len);
+                /* Get seed from in-kernel /dev/urandom */
                 get_random_bytes(drbg->seed_buf, drbg->seed_buf_len);
-                drbg_string_fill(&data1, drbg->seed_buf, drbg->seed_buf_len);
+
+                /* Get seed from Jitter RNG */
+                if (!drbg->jent ||
+                    crypto_rng_get_bytes(drbg->jent,
+                                         drbg->seed_buf + drbg->seed_buf_len,
+                                         drbg->seed_buf_len)) {
+                        drbg_string_fill(&data1, drbg->seed_buf,
+                                         drbg->seed_buf_len);
+                        pr_devel("DRBG: (re)seeding with %zu bytes of entropy\n",
+                                 drbg->seed_buf_len);
+                } else {
+                        drbg_string_fill(&data1, drbg->seed_buf,
+                                         drbg->seed_buf_len * 2);
+                        pr_devel("DRBG: (re)seeding with %zu bytes of entropy\n",
+                                 drbg->seed_buf_len * 2);
+                }
         }
         list_add_tail(&data1.list, &seedlist);
 
@@ -1131,7 +1150,7 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
          * Clear the initial entropy buffer as the async call may not overwrite
          * that buffer for quite some time.
          */
-        memzero_explicit(drbg->seed_buf, drbg->seed_buf_len);
+        memzero_explicit(drbg->seed_buf, drbg->seed_buf_len * 2);
         if (ret)
                 goto out;
         /*
@@ -1171,6 +1190,10 @@ static inline void drbg_dealloc_state(struct drbg_state *drbg)
 #endif
         kzfree(drbg->seed_buf);
         drbg->seed_buf = NULL;
+        if (drbg->jent) {
+                crypto_free_rng(drbg->jent);
+                drbg->jent = NULL;
+        }
 }
 
 /*
@@ -1246,14 +1269,29 @@ static inline int drbg_alloc_state(struct drbg_state *drbg)
                 ret = -EFAULT;
                 goto err;
         }
-        /* ensure we have sufficient buffer space for initial seed */
+        /*
+         * Ensure we have sufficient buffer space for initial seed which
+         * consists of the seed from get_random_bytes and the Jitter RNG.
+         */
         drbg->seed_buf_len = ((drbg->seed_buf_len + 1) / 2) * 3;
-        drbg->seed_buf = kzalloc(drbg->seed_buf_len, GFP_KERNEL);
+        drbg->seed_buf = kzalloc(drbg->seed_buf_len * 2, GFP_KERNEL);
         if (!drbg->seed_buf)
                 goto err;
 
         INIT_WORK(&drbg->seed_work, drbg_async_seed);
 
+        drbg->jent = crypto_alloc_rng("jitterentropy_rng", 0, 0);
+        if(IS_ERR(drbg->jent))
+        {
+                pr_info("DRBG: could not allocate Jitter RNG handle for seeding\n");
+                /*
+                 * As the Jitter RNG is a module that may not be present, we
+                 * continue with the operation and do not fully tie the DRBG
+                 * to the Jitter RNG.
+                 */
+                drbg->jent = NULL;
+        }
+
         return 0;
 
 err:
diff --git a/include/crypto/drbg.h b/include/crypto/drbg.h
index 46994b25dc85..c3f208dc83ee 100644
--- a/include/crypto/drbg.h
+++ b/include/crypto/drbg.h
@@ -123,6 +123,7 @@ struct drbg_state {
         struct work_struct seed_work;   /* asynchronous seeding support */
         u8 *seed_buf;                   /* buffer holding the seed */
         size_t seed_buf_len;
+        struct crypto_rng *jent;
         const struct drbg_state_ops *d_ops;
         const struct drbg_core *core;
         struct drbg_string test_data;