1 files changed, 77 insertions, 73 deletions

diff --git a/crypto/drbg.c b/crypto/drbg.c
index f72f340a1321..177983b6ae38 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -100,6 +100,7 @@
 #include <crypto/drbg.h>
 #include <crypto/internal/cipher.h>
 #include <linux/kernel.h>
+#include <linux/jiffies.h>
 
 /***************************************************************
  * Backend cipher definitions available to DRBG
@@ -1036,17 +1037,39 @@ static const struct drbg_state_ops drbg_hash_ops = {
  ******************************************************************/
 
 static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed,
-			      int reseed)
+			      int reseed, enum drbg_seed_state new_seed_state)
 {
 	int ret = drbg->d_ops->update(drbg, seed, reseed);
 
 	if (ret)
 		return ret;
 
-	drbg->seeded = true;
+	drbg->seeded = new_seed_state;
+	drbg->last_seed_time = jiffies;
 	/* 10.1.1.2 / 10.1.1.3 step 5 */
 	drbg->reseed_ctr = 1;
 
+	switch (drbg->seeded) {
+	case DRBG_SEED_STATE_UNSEEDED:
+		/* Impossible, but handle it to silence compiler warnings. */
+		fallthrough;
+	case DRBG_SEED_STATE_PARTIAL:
+		/*
+		 * Require frequent reseeds until the seed source is
+		 * fully initialized.
+		 */
+		drbg->reseed_threshold = 50;
+		break;
+
+	case DRBG_SEED_STATE_FULL:
+		/*
+		 * Seed source has become fully initialized, frequent
+		 * reseeds no longer required.
+		 */
+		drbg->reseed_threshold = drbg_max_requests(drbg);
+		break;
+	}
+
 	return ret;
 }
 
@@ -1066,12 +1089,10 @@ static inline int drbg_get_random_bytes(struct drbg_state *drbg,
 	return 0;
 }
 
-static void drbg_async_seed(struct work_struct *work)
+static int drbg_seed_from_random(struct drbg_state *drbg)
 {
 	struct drbg_string data;
 	LIST_HEAD(seedlist);
-	struct drbg_state *drbg = container_of(work, struct drbg_state,
-					       seed_work);
 	unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
 	unsigned char entropy[32];
 	int ret;
@@ -1082,26 +1103,35 @@ static void drbg_async_seed(struct work_struct *work)
 	drbg_string_fill(&data, entropy, entropylen);
 	list_add_tail(&data.list, &seedlist);
 
-	mutex_lock(&drbg->drbg_mutex);
-
 	ret = drbg_get_random_bytes(drbg, entropy, entropylen);
 	if (ret)
-		goto unlock;
+		goto out;
 
-	/* Set seeded to false so that if __drbg_seed fails the
-	 * next generate call will trigger a reseed.
-	 */
-	drbg->seeded = false;
+	ret = __drbg_seed(drbg, &seedlist, true, DRBG_SEED_STATE_FULL);
 
-	__drbg_seed(drbg, &seedlist, true);
+out:
+	memzero_explicit(entropy, entropylen);
+	return ret;
+}
 
-	if (drbg->seeded)
-		drbg->reseed_threshold = drbg_max_requests(drbg);
+static bool drbg_nopr_reseed_interval_elapsed(struct drbg_state *drbg)
+{
+	unsigned long next_reseed;
 
-unlock:
-	mutex_unlock(&drbg->drbg_mutex);
+	/* Don't ever reseed from get_random_bytes() in test mode. */
+	if (list_empty(&drbg->test_data.list))
+		return false;
 
-	memzero_explicit(entropy, entropylen);
+	/*
+	 * Obtain fresh entropy for the nopr DRBGs after 300s have
+	 * elapsed in order to still achieve sort of partial
+	 * prediction resistance over the time domain at least. Note
+	 * that the period of 300s has been chosen to match the
+	 * CRNG_RESEED_INTERVAL of the get_random_bytes()' chacha
+	 * rngs.
+	 */
+	next_reseed = drbg->last_seed_time + 300 * HZ;
+	return time_after(jiffies, next_reseed);
 }
 
 /*
@@ -1123,6 +1153,7 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
 	unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
 	struct drbg_string data1;
 	LIST_HEAD(seedlist);
+	enum drbg_seed_state new_seed_state = DRBG_SEED_STATE_FULL;
 
 	/* 9.1 / 9.2 / 9.3.1 step 3 */
 	if (pers && pers->len > (drbg_max_addtl(drbg))) {
@@ -1150,6 +1181,9 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
 		BUG_ON((entropylen * 2) > sizeof(entropy));
 
 		/* Get seed from in-kernel /dev/urandom */
+		if (!rng_is_initialized())
+			new_seed_state = DRBG_SEED_STATE_PARTIAL;
+
 		ret = drbg_get_random_bytes(drbg, entropy, entropylen);
 		if (ret)
 			goto out;
@@ -1159,11 +1193,14 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
 			pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
 				 entropylen);
 		} else {
-			/* Get seed from Jitter RNG */
+			/*
+			 * Get seed from Jitter RNG, failures are
+			 * fatal only in FIPS mode.
+			 */
 			ret = crypto_rng_get_bytes(drbg->jent,
 						   entropy + entropylen,
 						   entropylen);
-			if (ret) {
+			if (fips_enabled && ret) {
 				pr_devel("DRBG: jent failed with %d\n", ret);
 
 				/*
@@ -1206,7 +1243,7 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
 		memset(drbg->C, 0, drbg_statelen(drbg));
 	}
 
-	ret = __drbg_seed(drbg, &seedlist, reseed);
+	ret = __drbg_seed(drbg, &seedlist, reseed, new_seed_state);
 
 out:
 	memzero_explicit(entropy, entropylen * 2);
@@ -1386,19 +1423,26 @@ static int drbg_generate(struct drbg_state *drbg,
 	 * here. The spec is a bit convoluted here, we make it simpler.
 	 */
 	if (drbg->reseed_threshold < drbg->reseed_ctr)
-		drbg->seeded = false;
+		drbg->seeded = DRBG_SEED_STATE_UNSEEDED;
 
-	if (drbg->pr || !drbg->seeded) {
+	if (drbg->pr || drbg->seeded == DRBG_SEED_STATE_UNSEEDED) {
 		pr_devel("DRBG: reseeding before generation (prediction "
 			 "resistance: %s, state %s)\n",
 			 drbg->pr ? "true" : "false",
-			 drbg->seeded ? "seeded" : "unseeded");
+			 (drbg->seeded ==  DRBG_SEED_STATE_FULL ?
+			  "seeded" : "unseeded"));
 		/* 9.3.1 steps 7.1 through 7.3 */
 		len = drbg_seed(drbg, addtl, true);
 		if (len)
 			goto err;
 		/* 9.3.1 step 7.4 */
 		addtl = NULL;
+	} else if (rng_is_initialized() &&
+		   (drbg->seeded == DRBG_SEED_STATE_PARTIAL ||
+		    drbg_nopr_reseed_interval_elapsed(drbg))) {
+		len = drbg_seed_from_random(drbg);
+		if (len)
+			goto err;
 	}
 
 	if (addtl && 0 < addtl->len)
@@ -1491,51 +1535,23 @@ static int drbg_generate_long(struct drbg_state *drbg,
 	return 0;
 }
 
-static void drbg_schedule_async_seed(struct random_ready_callback *rdy)
-{
-	struct drbg_state *drbg = container_of(rdy, struct drbg_state,
-					       random_ready);
-
-	schedule_work(&drbg->seed_work);
-}
-
 static int drbg_prepare_hrng(struct drbg_state *drbg)
 {
-	int err;
-
 	/* We do not need an HRNG in test mode. */
 	if (list_empty(&drbg->test_data.list))
 		return 0;
 
 	drbg->jent = crypto_alloc_rng("jitterentropy_rng", 0, 0);
+	if (IS_ERR(drbg->jent)) {
+		const int err = PTR_ERR(drbg->jent);
 
-	INIT_WORK(&drbg->seed_work, drbg_async_seed);
-
-	drbg->random_ready.owner = THIS_MODULE;
-	drbg->random_ready.func = drbg_schedule_async_seed;
-
-	err = add_random_ready_callback(&drbg->random_ready);
-
-	switch (err) {
-	case 0:
-		break;
-
-	case -EALREADY:
-		err = 0;
-		fallthrough;
-
-	default:
-		drbg->random_ready.func = NULL;
-		return err;
+		drbg->jent = NULL;
+		if (fips_enabled || err != -ENOENT)
+			return err;
+		pr_info("DRBG: Continuing without Jitter RNG\n");
 	}
 
-	/*
-	 * Require frequent reseeds until the seed source is fully
-	 * initialized.
-	 */
-	drbg->reseed_threshold = 50;
-
-	return err;
+	return 0;
 }
 
 /*
@@ -1578,7 +1594,8 @@ static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
 	if (!drbg->core) {
 		drbg->core = &drbg_cores[coreref];
 		drbg->pr = pr;
-		drbg->seeded = false;
+		drbg->seeded = DRBG_SEED_STATE_UNSEEDED;
+		drbg->last_seed_time = 0;
 		drbg->reseed_threshold = drbg_max_requests(drbg);
 
 		ret = drbg_alloc_state(drbg);
@@ -1589,14 +1606,6 @@ static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
 		if (ret)
 			goto free_everything;
 
-		if (IS_ERR(drbg->jent)) {
-			ret = PTR_ERR(drbg->jent);
-			drbg->jent = NULL;
-			if (fips_enabled || ret != -ENOENT)
-				goto free_everything;
-			pr_info("DRBG: Continuing without Jitter RNG\n");
-		}
-
 		reseed = false;
 	}
 
@@ -1629,11 +1638,6 @@ free_everything:
  */
 static int drbg_uninstantiate(struct drbg_state *drbg)
 {
-	if (drbg->random_ready.func) {
-		del_random_ready_callback(&drbg->random_ready);
-		cancel_work_sync(&drbg->seed_work);
-	}
-
 	if (!IS_ERR_OR_NULL(drbg->jent))
 		crypto_free_rng(drbg->jent);
 	drbg->jent = NULL;