Merge tag 'random-6.2-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random

Pull random number generator updates from Jason Donenfeld:

 - Replace prandom_u32_max() and various open-coded variants of it,
   there is now a new family of functions that uses fast rejection
   sampling to choose properly uniformly random numbers within an
   interval:

       get_random_u32_below(ceil) - [0, ceil)
       get_random_u32_above(floor) - (floor, U32_MAX]
       get_random_u32_inclusive(floor, ceil) - [floor, ceil]

   Coccinelle was used to convert all current users of
   prandom_u32_max(), as well as many open-coded patterns, resulting in
   improvements throughout the tree.

   I'll have a "late" 6.1-rc1 pull for you that removes the now unused
   prandom_u32_max() function, just in case any other trees add a new
   use case of it that needs to converted. According to linux-next,
   there may be two trivial cases of prandom_u32_max() reintroductions
   that are fixable with a 's/.../.../'. So I'll have for you a final
   conversion patch doing that alongside the removal patch during the
   second week.

   This is a treewide change that touches many files throughout.

 - More consistent use of get_random_canary().

 - Updates to comments, documentation, tests, headers, and
   simplification in configuration.

 - The arch_get_random*_early() abstraction was only used by arm64 and
   wasn't entirely useful, so this has been replaced by code that works
   in all relevant contexts.

 - The kernel will use and manage random seeds in non-volatile EFI
   variables, refreshing a variable with a fresh seed when the RNG is
   initialized. The RNG GUID namespace is then hidden from efivarfs to
   prevent accidental leakage.

   These changes are split into random.c infrastructure code used in the
   EFI subsystem, in this pull request, and related support inside of
   EFISTUB, in Ard's EFI tree. These are co-dependent for full
   functionality, but the order of merging doesn't matter.

 - Part of the infrastructure added for the EFI support is also used for
   an improvement to the way vsprintf initializes its siphash key,
   replacing an sleep loop wart.

 - The hardware RNG framework now always calls its correct random.c
   input function, add_hwgenerator_randomness(), rather than sometimes
   going through helpers better suited for other cases.

 - The add_latent_entropy() function has long been called from the fork
   handler, but is a no-op when the latent entropy gcc plugin isn't
   used, which is fine for the purposes of latent entropy.

   But it was missing out on the cycle counter that was also being mixed
   in beside the latent entropy variable. So now, if the latent entropy
   gcc plugin isn't enabled, add_latent_entropy() will expand to a call
   to add_device_randomness(NULL, 0), which adds a cycle counter,
   without the absent latent entropy variable.

 - The RNG is now reseeded from a delayed worker, rather than on demand
   when used. Always running from a worker allows it to make use of the
   CPU RNG on platforms like S390x, whose instructions are too slow to
   do so from interrupts. It also has the effect of adding in new inputs
   more frequently with more regularity, amounting to a long term
   transcript of random values. Plus, it helps a bit with the upcoming
   vDSO implementation (which isn't yet ready for 6.2).

 - The jitter entropy algorithm now tries to execute on many different
   CPUs, round-robining, in hopes of hitting even more memory latencies
   and other unpredictable effects. It also will mix in a cycle counter
   when the entropy timer fires, in addition to being mixed in from the
   main loop, to account more explicitly for fluctuations in that timer
   firing. And the state it touches is now kept within the same cache
   line, so that it's assured that the different execution contexts will
   cause latencies.

* tag 'random-6.2-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random: (23 commits)
  random: include <linux/once.h> in the right header
  random: align entropy_timer_state to cache line
  random: mix in cycle counter when jitter timer fires
  random: spread out jitter callback to different CPUs
  random: remove extraneous period and add a missing one in comments
  efi: random: refresh non-volatile random seed when RNG is initialized
  vsprintf: initialize siphash key using notifier
  random: add back async readiness notifier
  random: reseed in delayed work rather than on-demand
  random: always mix cycle counter in add_latent_entropy()
  hw_random: use add_hwgenerator_randomness() for early entropy
  random: modernize documentation comment on get_random_bytes()
  random: adjust comment to account for removed function
  random: remove early archrandom abstraction
  random: use random.trust_{bootloader,cpu} command line option only
  stackprotector: actually use get_random_canary()
  stackprotector: move get_random_canary() into stackprotector.h
  treewide: use get_random_u32_inclusive() when possible
  treewide: use get_random_u32_{above,below}() instead of manual loop
  treewide: use get_random_u32_below() instead of deprecated function
  ...

41 files changed, 75 insertions, 87 deletions

diff --git a/net/802/garp.c b/net/802/garp.c
index fc9eb02a912f..77aac2763835 100644
--- a/net/802/garp.c
+++ b/net/802/garp.c
@@ -407,7 +407,7 @@ static void garp_join_timer_arm(struct garp_applicant *app)
 {
 	unsigned long delay;
 
-	delay = prandom_u32_max(msecs_to_jiffies(garp_join_time));
+	delay = get_random_u32_below(msecs_to_jiffies(garp_join_time));
 	mod_timer(&app->join_timer, jiffies + delay);
 }
 
diff --git a/net/802/mrp.c b/net/802/mrp.c
index 155f74d8b14f..8c6f0381023b 100644
--- a/net/802/mrp.c
+++ b/net/802/mrp.c
@@ -592,7 +592,7 @@ static void mrp_join_timer_arm(struct mrp_applicant *app)
 {
 	unsigned long delay;
 
-	delay = prandom_u32_max(msecs_to_jiffies(mrp_join_time));
+	delay = get_random_u32_below(msecs_to_jiffies(mrp_join_time));
 	mod_timer(&app->join_timer, jiffies + delay);
 }
 
diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
index 7f6a7c96ac92..114ee5da261f 100644
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -280,7 +280,7 @@ batadv_iv_ogm_emit_send_time(const struct batadv_priv *bat_priv)
 	unsigned int msecs;
 
 	msecs = atomic_read(&bat_priv->orig_interval) - BATADV_JITTER;
-	msecs += prandom_u32_max(2 * BATADV_JITTER);
+	msecs += get_random_u32_below(2 * BATADV_JITTER);
 
 	return jiffies + msecs_to_jiffies(msecs);
 }
@@ -288,7 +288,7 @@ batadv_iv_ogm_emit_send_time(const struct batadv_priv *bat_priv)
 /* when do we schedule a ogm packet to be sent */
 static unsigned long batadv_iv_ogm_fwd_send_time(void)
 {
-	return jiffies + msecs_to_jiffies(prandom_u32_max(BATADV_JITTER / 2));
+	return jiffies + msecs_to_jiffies(get_random_u32_below(BATADV_JITTER / 2));
 }
 
 /* apply hop penalty for a normal link */
diff --git a/net/batman-adv/bat_v_elp.c b/net/batman-adv/bat_v_elp.c
index f1741fbfb617..f9a58fb5442e 100644
--- a/net/batman-adv/bat_v_elp.c
+++ b/net/batman-adv/bat_v_elp.c
@@ -51,7 +51,7 @@ static void batadv_v_elp_start_timer(struct batadv_hard_iface *hard_iface)
 	unsigned int msecs;
 
 	msecs = atomic_read(&hard_iface->bat_v.elp_interval) - BATADV_JITTER;
-	msecs += prandom_u32_max(2 * BATADV_JITTER);
+	msecs += get_random_u32_below(2 * BATADV_JITTER);
 
 	queue_delayed_work(batadv_event_workqueue, &hard_iface->bat_v.elp_wq,
 			   msecs_to_jiffies(msecs));
diff --git a/net/batman-adv/bat_v_ogm.c b/net/batman-adv/bat_v_ogm.c
index 033639df96d8..addfd8c4fe95 100644
--- a/net/batman-adv/bat_v_ogm.c
+++ b/net/batman-adv/bat_v_ogm.c
@@ -90,7 +90,7 @@ static void batadv_v_ogm_start_queue_timer(struct batadv_hard_iface *hard_iface)
 	unsigned int msecs = BATADV_MAX_AGGREGATION_MS * 1000;
 
 	/* msecs * [0.9, 1.1] */
-	msecs += prandom_u32_max(msecs / 5) - (msecs / 10);
+	msecs += get_random_u32_below(msecs / 5) - (msecs / 10);
 	queue_delayed_work(batadv_event_workqueue, &hard_iface->bat_v.aggr_wq,
 			   msecs_to_jiffies(msecs / 1000));
 }
@@ -109,7 +109,7 @@ static void batadv_v_ogm_start_timer(struct batadv_priv *bat_priv)
 		return;
 
 	msecs = atomic_read(&bat_priv->orig_interval) - BATADV_JITTER;
-	msecs += prandom_u32_max(2 * BATADV_JITTER);
+	msecs += get_random_u32_below(2 * BATADV_JITTER);
 	queue_delayed_work(batadv_event_workqueue, &bat_priv->bat_v.ogm_wq,
 			   msecs_to_jiffies(msecs));
 }
diff --git a/net/batman-adv/network-coding.c b/net/batman-adv/network-coding.c
index 5f4aeeb60dc4..bf29fba4dde5 100644
--- a/net/batman-adv/network-coding.c
+++ b/net/batman-adv/network-coding.c
@@ -1009,7 +1009,7 @@ static struct batadv_nc_path *batadv_nc_get_path(struct batadv_priv *bat_priv,
 static u8 batadv_nc_random_weight_tq(u8 tq)
 {
 	/* randomize the estimated packet loss (max TQ - estimated TQ) */
-	u8 rand_tq = prandom_u32_max(BATADV_TQ_MAX_VALUE + 1 - tq);
+	u8 rand_tq = get_random_u32_below(BATADV_TQ_MAX_VALUE + 1 - tq);
 
 	/* convert to (randomized) estimated tq again */
 	return BATADV_TQ_MAX_VALUE - rand_tq;
diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index a92e7e485feb..81ce668b0b77 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -7373,9 +7373,8 @@ static int get_conn_info(struct sock *sk, struct hci_dev *hdev, void *data,
 	/* To avoid client trying to guess when to poll again for information we
 	 * calculate conn info age as random value between min/max set in hdev.
 	 */
-	conn_info_age = hdev->conn_info_min_age +
-			prandom_u32_max(hdev->conn_info_max_age -
-					hdev->conn_info_min_age);
+	conn_info_age = get_random_u32_inclusive(hdev->conn_info_min_age,
+						 hdev->conn_info_max_age - 1);
 
 	/* Query controller to refresh cached values if they are too old or were
 	 * never read.
diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index b670ba03a675..7e90f9e61d9b 100644
--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c
@@ -189,7 +189,7 @@ activate_next:
 		int time_ms = 0;
 
 		if (err)
-			time_ms = 10 + prandom_u32_max(16);
+			time_ms = 10 + get_random_u32_below(16);
 
 		j1939_tp_schedule_txtimer(first, time_ms);
 	}
diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index 55f29c9f9e08..67d36776aff4 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -1168,7 +1168,7 @@ static enum hrtimer_restart j1939_tp_txtimer(struct hrtimer *hrtimer)
 		if (session->tx_retry < J1939_XTP_TX_RETRY_LIMIT) {
 			session->tx_retry++;
 			j1939_tp_schedule_txtimer(session,
-						  10 + prandom_u32_max(16));
+						  10 + get_random_u32_below(16));
 		} else {
 			netdev_alert(priv->ndev, "%s: 0x%p: tx retry count reached\n",
 				     __func__, session);
diff --git a/net/ceph/mon_client.c b/net/ceph/mon_client.c
index db60217f911b..faabad6603db 100644
--- a/net/ceph/mon_client.c
+++ b/net/ceph/mon_client.c
@@ -222,7 +222,7 @@ static void pick_new_mon(struct ceph_mon_client *monc)
 				max--;
 		}
 
-		n = prandom_u32_max(max);
+		n = get_random_u32_below(max);
 		if (o >= 0 && n >= o)
 			n++;
 
diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 4e4f1e4bc265..11c04e7d928e 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -1479,7 +1479,7 @@ static bool target_should_be_paused(struct ceph_osd_client *osdc,
 
 static int pick_random_replica(const struct ceph_osds *acting)
 {
-	int i = prandom_u32_max(acting->size);
+	int i = get_random_u32_below(acting->size);
 
 	dout("%s picked osd%d, primary osd%d\n", __func__,
 	     acting->osds[i], acting->primary);
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 952a54763358..f00a79fc301b 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -111,7 +111,7 @@ static void neigh_cleanup_and_release(struct neighbour *neigh)
 
 unsigned long neigh_rand_reach_time(unsigned long base)
 {
-	return base ? prandom_u32_max(base) + (base >> 1) : 0;
+	return base ? get_random_u32_below(base) + (base >> 1) : 0;
 }
 EXPORT_SYMBOL(neigh_rand_reach_time);
 
@@ -1666,7 +1666,7 @@ void pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p,
 		    struct sk_buff *skb)
 {
 	unsigned long sched_next = jiffies +
-			prandom_u32_max(NEIGH_VAR(p, PROXY_DELAY));
+			get_random_u32_below(NEIGH_VAR(p, PROXY_DELAY));
 
 	if (p->qlen > NEIGH_VAR(p, PROXY_QLEN)) {
 		kfree_skb(skb);
diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index c3763056c554..760238196db1 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -2324,7 +2324,7 @@ static inline int f_pick(struct pktgen_dev *pkt_dev)
 				pkt_dev->curfl = 0; /*reset */
 		}
 	} else {
-		flow = prandom_u32_max(pkt_dev->cflows);
+		flow = get_random_u32_below(pkt_dev->cflows);
 		pkt_dev->curfl = flow;
 
 		if (pkt_dev->flows[flow].count > pkt_dev->lflow) {
@@ -2380,9 +2380,8 @@ static void set_cur_queue_map(struct pktgen_dev *pkt_dev)
 	else if (pkt_dev->queue_map_min <= pkt_dev->queue_map_max) {
 		__u16 t;
 		if (pkt_dev->flags & F_QUEUE_MAP_RND) {
-			t = prandom_u32_max(pkt_dev->queue_map_max -
-					    pkt_dev->queue_map_min + 1) +
-			    pkt_dev->queue_map_min;
+			t = get_random_u32_inclusive(pkt_dev->queue_map_min,
+						     pkt_dev->queue_map_max);
 		} else {
 			t = pkt_dev->cur_queue_map + 1;
 			if (t > pkt_dev->queue_map_max)
@@ -2411,7 +2410,7 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
 		__u32 tmp;
 
 		if (pkt_dev->flags & F_MACSRC_RND)
-			mc = prandom_u32_max(pkt_dev->src_mac_count);
+			mc = get_random_u32_below(pkt_dev->src_mac_count);
 		else {
 			mc = pkt_dev->cur_src_mac_offset++;
 			if (pkt_dev->cur_src_mac_offset >=
@@ -2437,7 +2436,7 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
 		__u32 tmp;
 
 		if (pkt_dev->flags & F_MACDST_RND)
-			mc = prandom_u32_max(pkt_dev->dst_mac_count);
+			mc = get_random_u32_below(pkt_dev->dst_mac_count);
 
 		else {
 			mc = pkt_dev->cur_dst_mac_offset++;
@@ -2469,18 +2468,17 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
 	}
 
 	if ((pkt_dev->flags & F_VID_RND) && (pkt_dev->vlan_id != 0xffff)) {
-		pkt_dev->vlan_id = prandom_u32_max(4096);
+		pkt_dev->vlan_id = get_random_u32_below(4096);
 	}
 
 	if ((pkt_dev->flags & F_SVID_RND) && (pkt_dev->svlan_id != 0xffff)) {
-		pkt_dev->svlan_id = prandom_u32_max(4096);
+		pkt_dev->svlan_id = get_random_u32_below(4096);
 	}
 
 	if (pkt_dev->udp_src_min < pkt_dev->udp_src_max) {
 		if (pkt_dev->flags & F_UDPSRC_RND)
-			pkt_dev->cur_udp_src = prandom_u32_max(
-				pkt_dev->udp_src_max - pkt_dev->udp_src_min) +
-				pkt_dev->udp_src_min;
+			pkt_dev->cur_udp_src = get_random_u32_inclusive(pkt_dev->udp_src_min,
+									pkt_dev->udp_src_max - 1);
 
 		else {
 			pkt_dev->cur_udp_src++;
@@ -2491,9 +2489,8 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
 
 	if (pkt_dev->udp_dst_min < pkt_dev->udp_dst_max) {
 		if (pkt_dev->flags & F_UDPDST_RND) {
-			pkt_dev->cur_udp_dst = prandom_u32_max(
-				pkt_dev->udp_dst_max - pkt_dev->udp_dst_min) +
-				pkt_dev->udp_dst_min;
+			pkt_dev->cur_udp_dst = get_random_u32_inclusive(pkt_dev->udp_dst_min,
+									pkt_dev->udp_dst_max - 1);
 		} else {
 			pkt_dev->cur_udp_dst++;
 			if (pkt_dev->cur_udp_dst >= pkt_dev->udp_dst_max)
@@ -2508,7 +2505,7 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
 		if (imn < imx) {
 			__u32 t;
 			if (pkt_dev->flags & F_IPSRC_RND)
-				t = prandom_u32_max(imx - imn) + imn;
+				t = get_random_u32_inclusive(imn, imx - 1);
 			else {
 				t = ntohl(pkt_dev->cur_saddr);
 				t++;
@@ -2530,8 +2527,7 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
 				if (pkt_dev->flags & F_IPDST_RND) {
 
 					do {
-						t = prandom_u32_max(imx - imn) +
-						    imn;
+						t = get_random_u32_inclusive(imn, imx - 1);
 						s = htonl(t);
 					} while (ipv4_is_loopback(s) ||
 						ipv4_is_multicast(s) ||
@@ -2578,9 +2574,8 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
 	if (pkt_dev->min_pkt_size < pkt_dev->max_pkt_size) {
 		__u32 t;
 		if (pkt_dev->flags & F_TXSIZE_RND) {
-			t = prandom_u32_max(pkt_dev->max_pkt_size -
-					    pkt_dev->min_pkt_size) +
-			    pkt_dev->min_pkt_size;
+			t = get_random_u32_inclusive(pkt_dev->min_pkt_size,
+						     pkt_dev->max_pkt_size - 1);
 		} else {
 			t = pkt_dev->cur_pkt_size + 1;
 			if (t > pkt_dev->max_pkt_size)
@@ -2589,7 +2584,7 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
 		pkt_dev->cur_pkt_size = t;
 	} else if (pkt_dev->n_imix_entries > 0) {
 		struct imix_pkt *entry;
-		__u32 t = prandom_u32_max(IMIX_PRECISION);
+		__u32 t = get_random_u32_below(IMIX_PRECISION);
 		__u8 entry_index = pkt_dev->imix_distribution[t];
 
 		entry = &pkt_dev->imix_entries[entry_index];
diff --git a/net/core/stream.c b/net/core/stream.c
index 75fded8495f5..5b1fe2b82eac 100644
--- a/net/core/stream.c
+++ b/net/core/stream.c
@@ -123,7 +123,7 @@ int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
 	DEFINE_WAIT_FUNC(wait, woken_wake_function);
 
 	if (sk_stream_memory_free(sk))
-		current_timeo = vm_wait = prandom_u32_max(HZ / 5) + 2;
+		current_timeo = vm_wait = get_random_u32_below(HZ / 5) + 2;
 
 	add_wait_queue(sk_sleep(sk), &wait);
 
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index d5d745c3e345..46aa2d65e40a 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -263,7 +263,7 @@ bool icmp_global_allow(void)
 		/* We want to use a credit of one in average, but need to randomize
 		 * it for security reasons.
 		 */
-		credit = max_t(int, credit - prandom_u32_max(3), 0);
+		credit = max_t(int, credit - get_random_u32_below(3), 0);
 		rc = true;
 	}
 	WRITE_ONCE(icmp_global.credit, credit);
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 81be3e0f0e70..c920aa9a62a9 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -213,7 +213,7 @@ static void igmp_stop_timer(struct ip_mc_list *im)
 /* It must be called with locked im->lock */
 static void igmp_start_timer(struct ip_mc_list *im, int max_delay)
 {
-	int tv = prandom_u32_max(max_delay);
+	int tv = get_random_u32_below(max_delay);
 
 	im->tm_running = 1;
 	if (!mod_timer(&im->timer, jiffies+tv+2))
@@ -222,7 +222,7 @@ static void igmp_start_timer(struct ip_mc_list *im, int max_delay)
 
 static void igmp_gq_start_timer(struct in_device *in_dev)
 {
-	int tv = prandom_u32_max(in_dev->mr_maxdelay);
+	int tv = get_random_u32_below(in_dev->mr_maxdelay);
 	unsigned long exp = jiffies + tv + 2;
 
 	if (in_dev->mr_gq_running &&
@@ -236,7 +236,7 @@ static void igmp_gq_start_timer(struct in_device *in_dev)
 
 static void igmp_ifc_start_timer(struct in_device *in_dev, int delay)
 {
-	int tv = prandom_u32_max(delay);
+	int tv = get_random_u32_below(delay);
 
 	if (!mod_timer(&in_dev->mr_ifc_timer, jiffies+tv+2))
 		in_dev_hold(in_dev);
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 4e84ed21d16f..f22051219b50 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -314,7 +314,7 @@ other_half_scan:
 	if (likely(remaining > 1))
 		remaining &= ~1U;
 
-	offset = prandom_u32_max(remaining);
+	offset = get_random_u32_below(remaining);
 	/* __inet_hash_connect() favors ports having @low parity
 	 * We do the opposite to not pollute connect() users.
 	 */
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 3cec471a2cd2..d039b4e732a3 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -1097,7 +1097,7 @@ ok:
 	 * on low contention the randomness is maximal and on high contention
 	 * it may be inexistent.
 	 */
-	i = max_t(int, i, prandom_u32_max(8) * 2);
+	i = max_t(int, i, get_random_u32_below(8) * 2);
 	WRITE_ONCE(table_perturb[index], READ_ONCE(table_perturb[index]) + i + 2);
 
 	/* Head lock still held and bh's disabled */
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index cd1fa9f70f1a..de6e3515ab4f 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -471,7 +471,7 @@ static u32 ip_idents_reserve(u32 hash, int segs)
 	old = READ_ONCE(*p_tstamp);
 
 	if (old != now && cmpxchg(p_tstamp, old, now) == old)
-		delta = prandom_u32_max(now - old);
+		delta = get_random_u32_below(now - old);
 
 	/* If UBSAN reports an error there, please make sure your compiler
 	 * supports -fno-strict-overflow before reporting it that was a bug
@@ -689,7 +689,7 @@ static void update_or_create_fnhe(struct fib_nh_common *nhc, __be32 daddr,
 	} else {
 		/* Randomize max depth to avoid some side channels attacks. */
 		int max_depth = FNHE_RECLAIM_DEPTH +
-				prandom_u32_max(FNHE_RECLAIM_DEPTH);
+				get_random_u32_below(FNHE_RECLAIM_DEPTH);
 
 		while (depth > max_depth) {
 			fnhe_remove_oldest(hash);
diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c
index 54eec33c6e1c..d2c470524e58 100644
--- a/net/ipv4/tcp_bbr.c
+++ b/net/ipv4/tcp_bbr.c
@@ -618,7 +618,7 @@ static void bbr_reset_probe_bw_mode(struct sock *sk)
 	struct bbr *bbr = inet_csk_ca(sk);
 
 	bbr->mode = BBR_PROBE_BW;
-	bbr->cycle_idx = CYCLE_LEN - 1 - prandom_u32_max(bbr_cycle_rand);
+	bbr->cycle_idx = CYCLE_LEN - 1 - get_random_u32_below(bbr_cycle_rand);
 	bbr_advance_cycle_phase(sk);	/* flip to next phase of gain cycle */
 }
 
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 0640453fce54..23cf418efe4f 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3646,7 +3646,8 @@ static void tcp_send_challenge_ack(struct sock *sk)
 		u32 half = (ack_limit + 1) >> 1;
 
 		WRITE_ONCE(net->ipv4.tcp_challenge_timestamp, now);
-		WRITE_ONCE(net->ipv4.tcp_challenge_count, half + prandom_u32_max(ack_limit));
+		WRITE_ONCE(net->ipv4.tcp_challenge_count,
+			   get_random_u32_inclusive(half, ack_limit + half - 1));
 	}
 	count = READ_ONCE(net->ipv4.tcp_challenge_count);
 	if (count > 0) {
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 9c3f5202a97b..d720f6f5de3f 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -104,7 +104,7 @@ static inline u32 cstamp_delta(unsigned long cstamp)
 static inline s32 rfc3315_s14_backoff_init(s32 irt)
 {
 	/* multiply 'initial retransmission time' by 0.9 .. 1.1 */
-	u64 tmp = (900000 + prandom_u32_max(200001)) * (u64)irt;
+	u64 tmp = get_random_u32_inclusive(900000, 1100000) * (u64)irt;
 	do_div(tmp, 1000000);
 	return (s32)tmp;
 }
@@ -112,11 +112,11 @@ static inline s32 rfc3315_s14_backoff_init(s32 irt)
 static inline s32 rfc3315_s14_backoff_update(s32 rt, s32 mrt)
 {
 	/* multiply 'retransmission timeout' by 1.9 .. 2.1 */
-	u64 tmp = (1900000 + prandom_u32_max(200001)) * (u64)rt;
+	u64 tmp = get_random_u32_inclusive(1900000, 2100000) * (u64)rt;
 	do_div(tmp, 1000000);
 	if ((s32)tmp > mrt) {
 		/* multiply 'maximum retransmission time' by 0.9 .. 1.1 */
-		tmp = (900000 + prandom_u32_max(200001)) * (u64)mrt;
+		tmp = get_random_u32_inclusive(900000, 1100000) * (u64)mrt;
 		do_div(tmp, 1000000);
 	}
 	return (s32)tmp;
@@ -3967,7 +3967,7 @@ static void addrconf_dad_kick(struct inet6_ifaddr *ifp)
 	if (ifp->flags & IFA_F_OPTIMISTIC)
 		rand_num = 0;
 	else
-		rand_num = prandom_u32_max(idev->cnf.rtr_solicit_delay ?: 1);
+		rand_num = get_random_u32_below(idev->cnf.rtr_solicit_delay ? : 1);
 
 	nonce = 0;
 	if (idev->cnf.enhanced_dad ||
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 7860383295d8..1c02160cf7a4 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1050,7 +1050,7 @@ bool ipv6_chk_mcast_addr(struct net_device *dev, const struct in6_addr *group,
 /* called with mc_lock */
 static void mld_gq_start_work(struct inet6_dev *idev)
 {
-	unsigned long tv = prandom_u32_max(idev->mc_maxdelay);
+	unsigned long tv = get_random_u32_below(idev->mc_maxdelay);
 
 	idev->mc_gq_running = 1;
 	if (!mod_delayed_work(mld_wq, &idev->mc_gq_work, tv + 2))
@@ -1068,7 +1068,7 @@ static void mld_gq_stop_work(struct inet6_dev *idev)
 /* called with mc_lock */
 static void mld_ifc_start_work(struct inet6_dev *idev, unsigned long delay)
 {
-	unsigned long tv = prandom_u32_max(delay);
+	unsigned long tv = get_random_u32_below(delay);
 
 	if (!mod_delayed_work(mld_wq, &idev->mc_ifc_work, tv + 2))
 		in6_dev_hold(idev);
@@ -1085,7 +1085,7 @@ static void mld_ifc_stop_work(struct inet6_dev *idev)
 /* called with mc_lock */
 static void mld_dad_start_work(struct inet6_dev *idev, unsigned long delay)
 {
-	unsigned long tv = prandom_u32_max(delay);
+	unsigned long tv = get_random_u32_below(delay);
 
 	if (!mod_delayed_work(mld_wq, &idev->mc_dad_work, tv + 2))
 		in6_dev_hold(idev);
@@ -1130,7 +1130,7 @@ static void igmp6_group_queried(struct ifmcaddr6 *ma, unsigned long resptime)
 	}
 
 	if (delay >= resptime)
-		delay = prandom_u32_max(resptime);
+		delay = get_random_u32_below(resptime);
 
 	if (!mod_delayed_work(mld_wq, &ma->mca_work, delay))
 		refcount_inc(&ma->mca_refcnt);
@@ -2574,7 +2574,7 @@ static void igmp6_join_group(struct ifmcaddr6 *ma)
 
 	igmp6_send(&ma->mca_addr, ma->idev->dev, ICMPV6_MGM_REPORT);
 
-	delay = prandom_u32_max(unsolicited_report_interval(ma->idev));
+	delay = get_random_u32_below(unsolicited_report_interval(ma->idev));
 
 	if (cancel_delayed_work(&ma->mca_work)) {
 		refcount_dec(&ma->mca_refcnt);
diff --git a/net/ipv6/output_core.c b/net/ipv6/output_core.c
index 2685c3f15e9d..b5205311f372 100644
--- a/net/ipv6/output_core.c
+++ b/net/ipv6/output_core.c
@@ -15,13 +15,7 @@ static u32 __ipv6_select_ident(struct net *net,
 			       const struct in6_addr *dst,
 			       const struct in6_addr *src)
 {
-	u32 id;
-
-	do {
-		id = get_random_u32();
-	} while (!id);
-
-	return id;
+	return get_random_u32_above(0);
 }
 
 /* This function exists only for tap drivers that must support broken
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 2f355f0ec32a..e74e0361fd92 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1713,7 +1713,7 @@ static int rt6_insert_exception(struct rt6_info *nrt,
 	net->ipv6.rt6_stats->fib_rt_cache++;
 
 	/* Randomize max depth to avoid some side channels attacks. */
-	max_depth = FIB6_MAX_DEPTH + prandom_u32_max(FIB6_MAX_DEPTH);
+	max_depth = FIB6_MAX_DEPTH + get_random_u32_below(FIB6_MAX_DEPTH);
 	while (bucket->depth > max_depth)
 		rt6_exception_remove_oldest(bucket);
 
diff --git a/net/netfilter/ipvs/ip_vs_twos.c b/net/netfilter/ipvs/ip_vs_twos.c
index f2579fc9c75b..3308e4cc740a 100644
--- a/net/netfilter/ipvs/ip_vs_twos.c
+++ b/net/netfilter/ipvs/ip_vs_twos.c
@@ -71,8 +71,8 @@ static struct ip_vs_dest *ip_vs_twos_schedule(struct ip_vs_service *svc,
 	 * from 0 to total_weight
 	 */
 	total_weight += 1;
-	rweight1 = prandom_u32_max(total_weight);
-	rweight2 = prandom_u32_max(total_weight);
+	rweight1 = get_random_u32_below(total_weight);
+	rweight2 = get_random_u32_below(total_weight);
 
 	/* Pick two weighted servers */
 	list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 23b3fedd619a..8006ca862551 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -906,7 +906,7 @@ nf_conntrack_hash_check_insert(struct nf_conn *ct)
 					   nf_ct_zone_id(nf_ct_zone(ct), IP_CT_DIR_REPLY));
 	} while (nf_conntrack_double_lock(net, hash, reply_hash, sequence));
 
-	max_chainlen = MIN_CHAINLEN + prandom_u32_max(MAX_CHAINLEN);
+	max_chainlen = MIN_CHAINLEN + get_random_u32_below(MAX_CHAINLEN);
 
 	/* See if there's one in the list already, including reverse */
 	hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[hash], hnnode) {
@@ -1227,7 +1227,7 @@ __nf_conntrack_confirm(struct sk_buff *skb)
 		goto dying;
 	}
 
-	max_chainlen = MIN_CHAINLEN + prandom_u32_max(MAX_CHAINLEN);
+	max_chainlen = MIN_CHAINLEN + get_random_u32_below(MAX_CHAINLEN);
 	/* See if there's one in the list already, including reverse:
 	   NAT could have grabbed it without realizing, since we're
 	   not in the hash.  If there is, we lost race. */
diff --git a/net/netfilter/nf_nat_helper.c b/net/netfilter/nf_nat_helper.c
index a95a25196943..bf591e6af005 100644
--- a/net/netfilter/nf_nat_helper.c
+++ b/net/netfilter/nf_nat_helper.c
@@ -223,7 +223,7 @@ u16 nf_nat_exp_find_port(struct nf_conntrack_expect *exp, u16 port)
 		if (res != -EBUSY || (--attempts_left < 0))
 			break;
 
-		port = min + prandom_u32_max(range);
+		port = min + get_random_u32_below(range);
 	}
 
 	return 0;
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index a662e8a5ff84..7a401d94463a 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -835,7 +835,7 @@ retry:
 		/* Bind collision, search negative portid values. */
 		if (rover == -4096)
 			/* rover will be in range [S32_MIN, -4097] */
-			rover = S32_MIN + prandom_u32_max(-4096 - S32_MIN);
+			rover = S32_MIN + get_random_u32_below(-4096 - S32_MIN);
 		else if (rover >= -4096)
 			rover = -4097;
 		portid = rover--;
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 1ab65f7f2a0a..96fea8afc004 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1350,7 +1350,7 @@ static bool fanout_flow_is_huge(struct packet_sock *po, struct sk_buff *skb)
 		if (READ_ONCE(history[i]) == rxhash)
 			count++;
 
-	victim = prandom_u32_max(ROLLOVER_HLEN);
+	victim = get_random_u32_below(ROLLOVER_HLEN);
 
 	/* Avoid dirtying the cache line if possible */
 	if (READ_ONCE(history[victim]) != rxhash)
@@ -1386,7 +1386,7 @@ static unsigned int fanout_demux_rnd(struct packet_fanout *f,
 				     struct sk_buff *skb,
 				     unsigned int num)
 {
-	return prandom_u32_max(num);
+	return get_random_u32_below(num);
 }
 
 static unsigned int fanout_demux_rollover(struct packet_fanout *f,
diff --git a/net/sched/act_gact.c b/net/sched/act_gact.c
index 62d682b96b88..be267ffaaba7 100644
--- a/net/sched/act_gact.c
+++ b/net/sched/act_gact.c
@@ -25,7 +25,7 @@ static struct tc_action_ops act_gact_ops;
 static int gact_net_rand(struct tcf_gact *gact)
 {
 	smp_rmb(); /* coupled with smp_wmb() in tcf_gact_init() */
-	if (prandom_u32_max(gact->tcfg_pval))
+	if (get_random_u32_below(gact->tcfg_pval))
 		return gact->tcf_action;
 	return gact->tcfg_paction;
 }
diff --git a/net/sched/act_sample.c b/net/sched/act_sample.c
index 7a25477f5d99..4194480746b0 100644
--- a/net/sched/act_sample.c
+++ b/net/sched/act_sample.c
@@ -168,7 +168,7 @@ static int tcf_sample_act(struct sk_buff *skb, const struct tc_action *a,
 	psample_group = rcu_dereference_bh(s->psample_group);
 
 	/* randomly sample packets according to rate */
-	if (psample_group && (prandom_u32_max(s->rate) == 0)) {
+	if (psample_group && (get_random_u32_below(s->rate) == 0)) {
 		if (!skb_at_tc_ingress(skb)) {
 			md.in_ifindex = skb->skb_iif;
 			md.out_ifindex = skb->dev->ifindex;
diff --git a/net/sched/sch_choke.c b/net/sched/sch_choke.c
index 3ac3e5c80b6f..19c851125901 100644
--- a/net/sched/sch_choke.c
+++ b/net/sched/sch_choke.c
@@ -183,7 +183,7 @@ static struct sk_buff *choke_peek_random(const struct choke_sched_data *q,
 	int retrys = 3;
 
 	do {
-		*pidx = (q->head + prandom_u32_max(choke_len(q))) & q->tab_mask;
+		*pidx = (q->head + get_random_u32_below(choke_len(q))) & q->tab_mask;
 		skb = q->tab[*pidx];
 		if (skb)
 			return skb;
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index fb00ac40ecb7..6ef3021e1169 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -513,8 +513,8 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 			goto finish_segs;
 		}
 
-		skb->data[prandom_u32_max(skb_headlen(skb))] ^=
-			1<<prandom_u32_max(8);
+		skb->data[get_random_u32_below(skb_headlen(skb))] ^=
+			1<<get_random_u32_below(8);
 	}
 
 	if (unlikely(sch->q.qlen >= sch->limit)) {
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 83628c347744..cfe72085fdc4 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -8319,7 +8319,7 @@ static int sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
 
 		inet_get_local_port_range(net, &low, &high);
 		remaining = (high - low) + 1;
-		rover = prandom_u32_max(remaining) + low;
+		rover = get_random_u32_below(remaining) + low;
 
 		do {
 			rover++;
diff --git a/net/sctp/transport.c b/net/sctp/transport.c
index f8fd98784977..ca1eba95c293 100644
--- a/net/sctp/transport.c
+++ b/net/sctp/transport.c
@@ -199,7 +199,7 @@ void sctp_transport_reset_hb_timer(struct sctp_transport *transport)
 	if ((time_before(transport->hb_timer.expires, expires) ||
 	     !timer_pending(&transport->hb_timer)) &&
 	    !mod_timer(&transport->hb_timer,
-		       expires + prandom_u32_max(transport->rto)))
+		       expires + get_random_u32_below(transport->rto)))
 		sctp_transport_hold(transport);
 }
 
diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index f075a9fb5ccc..95ff74706104 100644
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -677,7 +677,7 @@ static void cache_limit_defers(void)
 
 	/* Consider removing either the first or the last */
 	if (cache_defer_cnt > DFR_MAX) {
-		if (prandom_u32_max(2))
+		if (get_random_u32_below(2))
 			discard = list_entry(cache_defer_list.next,
 					     struct cache_deferred_req, recent);
 		else
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 915b9902f673..2e4987dcba29 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1619,7 +1619,7 @@ static int xs_get_random_port(void)
 	if (max < min)
 		return -EADDRINUSE;
 	range = max - min + 1;
-	rand = prandom_u32_max(range);
+	rand = get_random_u32_below(range);
 	return rand + min;
 }
 
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index e902b01ea3cb..b35c8701876a 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -3010,7 +3010,7 @@ static int tipc_sk_insert(struct tipc_sock *tsk)
 	struct net *net = sock_net(sk);
 	struct tipc_net *tn = net_generic(net, tipc_net_id);
 	u32 remaining = (TIPC_MAX_PORT - TIPC_MIN_PORT) + 1;
-	u32 portid = prandom_u32_max(remaining) + TIPC_MIN_PORT;
+	u32 portid = get_random_u32_below(remaining) + TIPC_MIN_PORT;
 
 	while (remaining--) {
 		portid++;
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 884eca7f6743..d593d5b6d4b1 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -626,8 +626,7 @@ static int __vsock_bind_connectible(struct vsock_sock *vsk,
 	struct sockaddr_vm new_addr;
 
 	if (!port)
-		port = LAST_RESERVED_PORT + 1 +
-			prandom_u32_max(U32_MAX - LAST_RESERVED_PORT);
+		port = get_random_u32_above(LAST_RESERVED_PORT);
 
 	vsock_addr_init(&new_addr, addr->svm_cid, addr->svm_port);
 
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 3d2fe7712ac5..d63a3644ee1a 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -2072,7 +2072,7 @@ int xfrm_alloc_spi(struct xfrm_state *x, u32 low, u32 high)
 	} else {
 		u32 spi = 0;
 		for (h = 0; h < high-low+1; h++) {
-			spi = low + prandom_u32_max(high - low + 1);
+			spi = get_random_u32_inclusive(low, high);
 			x0 = xfrm_state_lookup(net, mark, &x->id.daddr, htonl(spi), x->id.proto, x->props.family);
 			if (x0 == NULL) {
 				newspi = htonl(spi);