[PATCH] random: defer use of bootloader randomness to random_init()

@@ -678,7 +678,6 @@ static void __cold _credit_init_bits(size_t bits)
  *
  *	void add_device_randomness(const void *buf, size_t len);
  *	void add_hwgenerator_randomness(const void *buf, size_t len, size_t entropy);
- *	void add_bootloader_randomness(const void *buf, size_t len);
  *	void add_vmfork_randomness(const void *unique_vm_id, size_t len);
  *	void add_interrupt_randomness(int irq);
  *	void add_input_randomness(unsigned int type, unsigned int code, unsigned int value);

@@ -696,10 +695,6 @@ static void __cold _credit_init_bits(size_t bits)
  * entropy as specified by the caller. If the entropy pool is full it will
  * block until more entropy is needed.
  *
- * add_bootloader_randomness() is called by bootloader drivers, such as EFI
- * and device tree, and credits its input depending on whether or not the
- * configuration option CONFIG_RANDOM_TRUST_BOOTLOADER is set.
- *
  * add_vmfork_randomness() adds a unique (but not necessarily secret) ID
  * representing the current instance of a VM to the pool, without crediting,
  * and then force-reseeds the crng so that it takes effect immediately.

@@ -765,6 +760,18 @@ static int random_pm_notification(struct notifier_block *nb, unsigned long actio
 
 static struct notifier_block pm_notifier = { .notifier_call = random_pm_notification };
 
+/*
+ * Handle random seed passed by bootloader. The buf pointer
+ * must remain alive during the kernel's init sequence.
+ */
+static __initdata const void *bootloader_seed;
+static __initdata size_t bootloader_seed_bytes;
+void __init register_bootloader_seed(const void *buf, size_t len)
+{
+	bootloader_seed = buf;
+	bootloader_seed_bytes = len;
+}
+
 /*
  * The first collection of entropy occurs at system boot while interrupts
  * are still turned off. Here we push in latent entropy, RDSEED, a timestamp,

@@ -793,6 +800,8 @@ int __init random_init(const char *command_line)
 		}
 		_mix_pool_bytes(&entropy, sizeof(entropy));
 	}
+	if (bootloader_seed && bootloader_seed_bytes)
+		_mix_pool_bytes(bootloader_seed, bootloader_seed_bytes);
 	_mix_pool_bytes(&now, sizeof(now));
 	_mix_pool_bytes(utsname(), sizeof(*(utsname())));
 	_mix_pool_bytes(command_line, strlen(command_line));

@@ -800,9 +809,10 @@ int __init random_init(const char *command_line)
 
 	if (crng_ready())
 		crng_reseed();
-	else if (trust_cpu)
-		_credit_init_bits(arch_bytes * 8);
-	used_arch_random = arch_bytes * 8 >= POOL_READY_BITS;
+	else
+		_credit_init_bits((trust_cpu ? arch_bytes * 8 : 0) +
+				  (trust_bootloader ? bootloader_seed_bytes * 8 : 0));
+	used_arch_random = arch_bytes * 8 + bootloader_seed_bytes * 8 >= POOL_READY_BITS;
 
 	WARN_ON(register_pm_notifier(&pm_notifier));
 

@@ -861,18 +871,6 @@ void add_hwgenerator_randomness(const void *buf, size_t len, size_t entropy)
 }
 EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);
 
-/*
- * Handle random seed passed by bootloader, and credit it if
- * CONFIG_RANDOM_TRUST_BOOTLOADER is set.
- */
-void __cold add_bootloader_randomness(const void *buf, size_t len)
-{
-	mix_pool_bytes(buf, len);
-	if (trust_bootloader)
-		credit_init_bits(len * 8);
-}
-EXPORT_SYMBOL_GPL(add_bootloader_randomness);
-
 #if IS_ENABLED(CONFIG_VMGENID)
 static BLOCKING_NOTIFIER_HEAD(vmfork_chain);
 

@@ -614,7 +614,7 @@ int __init efi_config_parse_tables(const efi_config_table_t *config_tables,
 					      sizeof(*seed) + size);
 			if (seed != NULL) {
 				pr_notice("seeding entropy pool\n");
-				add_bootloader_randomness(seed->bits, size);
+				register_bootloader_seed(seed->bits, size);
 				early_memunmap(seed, sizeof(*seed) + size);
 			} else {
 				pr_err("Could not map UEFI random seed!\n");

@@ -1201,7 +1201,7 @@ int __init early_init_dt_scan_chosen(char *cmdline)
 
 	rng_seed = of_get_flat_dt_prop(node, "rng-seed", &l);
 	if (rng_seed && l > 0) {
-		add_bootloader_randomness(rng_seed, l);
+		register_bootloader_seed(rng_seed, l);
 
 		/* try to clear seed so it won't be found. */
 		fdt_nop_property(initial_boot_params, node, "rng-seed");

@@ -13,7 +13,6 @@
 struct notifier_block;
 
 void add_device_randomness(const void *buf, size_t len);
-void add_bootloader_randomness(const void *buf, size_t len);
 void add_input_randomness(unsigned int type, unsigned int code,
 			  unsigned int value) __latent_entropy;
 void add_interrupt_randomness(int irq) __latent_entropy;

@@ -72,6 +71,7 @@ static inline unsigned long get_random_canary(void)
 	return get_random_long() & CANARY_MASK;
 }
 
+void __init register_bootloader_seed(const void *buf, size_t len);
 int __init random_init(const char *command_line);
 bool rng_is_initialized(void);
 bool rng_has_arch_random(void);