1 files changed, 35 insertions, 24 deletions

diff --git a/crypto/drbg.c b/crypto/drbg.c
index 2a7860f73288..a76b3cb03cf4 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -646,7 +646,7 @@ out:
 /* Generate function of CTR DRBG as defined in 10.2.1.5.2 */
 static int drbg_ctr_generate(struct drbg_state *drbg,
                              unsigned char *buf, unsigned int buflen,
-                             struct drbg_string *addtl)
+                             struct list_head *addtl)
 {
         int len = 0;
         int ret = 0;
@@ -656,11 +656,8 @@ static int drbg_ctr_generate(struct drbg_state *drbg,
         memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
 
         /* 10.2.1.5.2 step 2 */
-        if (addtl && 0 < addtl->len) {
-                LIST_HEAD(addtllist);
-
-                list_add_tail(&addtl->list, &addtllist);
-                ret = drbg_ctr_update(drbg, &addtllist, 2);
+        if (addtl && !list_empty(addtl)) {
+                ret = drbg_ctr_update(drbg, addtl, 2);
                 if (ret)
                         return 0;
         }
@@ -777,7 +774,7 @@ static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed,
 static int drbg_hmac_generate(struct drbg_state *drbg,
                               unsigned char *buf,
                               unsigned int buflen,
-                              struct drbg_string *addtl)
+                              struct list_head *addtl)
 {
         int len = 0;
         int ret = 0;
@@ -785,11 +782,8 @@ static int drbg_hmac_generate(struct drbg_state *drbg,
         LIST_HEAD(datalist);
 
         /* 10.1.2.5 step 2 */
-        if (addtl && 0 < addtl->len) {
-                LIST_HEAD(addtllist);
-
-                list_add_tail(&addtl->list, &addtllist);
-                ret = drbg_hmac_update(drbg, &addtllist, 1);
+        if (addtl && !list_empty(addtl)) {
+                ret = drbg_hmac_update(drbg, addtl, 1);
                 if (ret)
                         return ret;
         }
@@ -813,14 +807,10 @@ static int drbg_hmac_generate(struct drbg_state *drbg,
         }
 
         /* 10.1.2.5 step 6 */
-        if (addtl && 0 < addtl->len) {
-                LIST_HEAD(addtllist);
-
-                list_add_tail(&addtl->list, &addtllist);
-                ret = drbg_hmac_update(drbg, &addtllist, 1);
-        } else {
+        if (addtl && !list_empty(addtl))
+                ret = drbg_hmac_update(drbg, addtl, 1);
+        else
                 ret = drbg_hmac_update(drbg, NULL, 1);
-        }
         if (ret)
                 return ret;
 
@@ -944,7 +934,7 @@ out:
 
 /* processing of additional information string for Hash DRBG */
 static int drbg_hash_process_addtl(struct drbg_state *drbg,
-                                   struct drbg_string *addtl)
+                                   struct list_head *addtl)
 {
         int ret = 0;
         struct drbg_string data1, data2;
@@ -955,7 +945,7 @@ static int drbg_hash_process_addtl(struct drbg_state *drbg,
         memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
 
         /* 10.1.1.4 step 2 */
-        if (!addtl || 0 == addtl->len)
+        if (!addtl || list_empty(addtl))
                 return 0;
 
         /* 10.1.1.4 step 2a */
@@ -963,7 +953,7 @@ static int drbg_hash_process_addtl(struct drbg_state *drbg,
         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
         list_add_tail(&data1.list, &datalist);
         list_add_tail(&data2.list, &datalist);
-        list_add_tail(&addtl->list, &datalist);
+        list_splice_tail(addtl, &datalist);
         ret = drbg_kcapi_hash(drbg, NULL, drbg->scratchpad, &datalist);
         if (ret)
                 goto out;
@@ -1029,7 +1019,7 @@ out:
 /* generate function for Hash DRBG as defined in  10.1.1.4 */
 static int drbg_hash_generate(struct drbg_state *drbg,
                               unsigned char *buf, unsigned int buflen,
-                              struct drbg_string *addtl)
+                              struct list_head *addtl)
 {
         int len = 0;
         int ret = 0;
@@ -1347,6 +1337,12 @@ static int drbg_generate(struct drbg_state *drbg,
 {
         int len = 0;
         struct drbg_state *shadow = NULL;
+        LIST_HEAD(addtllist);
+        struct drbg_string timestamp;
+        union {
+                cycles_t cycles;
+                unsigned char char_cycles[sizeof(cycles_t)];
+        } now;
 
         if (0 == buflen || !buf) {
                 pr_devel("DRBG: no output buffer provided\n");
@@ -1407,8 +1403,23 @@ static int drbg_generate(struct drbg_state *drbg,
                 /* 9.3.1 step 7.4 */
                 addtl = NULL;
         }
+
+        /*
+         * Mix the time stamp into the DRBG state if the DRBG is not in
+         * test mode. If there are two callers invoking the DRBG at the same
+         * time, i.e. before the first caller merges its shadow state back,
+         * both callers would obtain the same random number stream without
+         * changing the state here.
+         */
+        if (!drbg->test_data) {
+                now.cycles = random_get_entropy();
+                drbg_string_fill(&timestamp, now.char_cycles, sizeof(cycles_t));
+                list_add_tail(&timestamp.list, &addtllist);
+        }
+        if (addtl && 0 < addtl->len)
+                list_add_tail(&addtl->list, &addtllist);
         /* 9.3.1 step 8 and 10 */
-        len = shadow->d_ops->generate(shadow, buf, buflen, addtl);
+        len = shadow->d_ops->generate(shadow, buf, buflen, &addtllist);
 
         /* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
         shadow->reseed_ctr++;