random: use hash function for crng_slow_load()

commit 66e4c2b9541503d721e936cc3898c9f25f4591ff upstream.

Since we have a hash function that's really fast, and the goal of
crng_slow_load() is reportedly to "touch all of the crng's state", we
can just hash the old state together with the new state and call it a
day. This way we dont need to reason about another LFSR or worry about
various attacks there. This code is only ever used at early boot and
then never again.

Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 38 insertions, 41 deletions

diff --git a/include/trace/events/random.h b/include/trace/events/random.h
index 6f3a9b90ce81..29ebb6200663 100644
--- a/include/trace/events/random.h
+++ b/include/trace/events/random.h
@@ -9,13 +9,13 @@
 #include <linux/tracepoint.h>
 
 TRACE_EVENT(add_device_randomness,
-	TP_PROTO(int bytes, unsigned long IP),
+	TP_PROTO(size_t bytes, unsigned long IP),
 
 	TP_ARGS(bytes, IP),
 
 	TP_STRUCT__entry(
-		__field(	  int,	bytes			)
-		__field(unsigned long,	IP			)
+		__field(size_t,		bytes	)
+		__field(unsigned long,	IP	)
 	),
 
 	TP_fast_assign(
@@ -23,18 +23,18 @@ TRACE_EVENT(add_device_randomness,
 		__entry->IP		= IP;
 	),
 
-	TP_printk("bytes %d caller %pS",
+	TP_printk("bytes %zu caller %pS",
 		__entry->bytes, (void *)__entry->IP)
 );
 
 DECLARE_EVENT_CLASS(random__mix_pool_bytes,
-	TP_PROTO(int bytes, unsigned long IP),
+	TP_PROTO(size_t bytes, unsigned long IP),
 
 	TP_ARGS(bytes, IP),
 
 	TP_STRUCT__entry(
-		__field(	  int,	bytes			)
-		__field(unsigned long,	IP			)
+		__field(size_t,		bytes	)
+		__field(unsigned long,	IP	)
 	),
 
 	TP_fast_assign(
@@ -42,12 +42,12 @@ DECLARE_EVENT_CLASS(random__mix_pool_bytes,
 		__entry->IP		= IP;
 	),
 
-	TP_printk("input pool: bytes %d caller %pS",
+	TP_printk("input pool: bytes %zu caller %pS",
 		  __entry->bytes, (void *)__entry->IP)
 );
 
 DEFINE_EVENT(random__mix_pool_bytes, mix_pool_bytes,
-	TP_PROTO(int bytes, unsigned long IP),
+	TP_PROTO(size_t bytes, unsigned long IP),
 
 	TP_ARGS(bytes, IP)
 );
@@ -59,13 +59,13 @@ DEFINE_EVENT(random__mix_pool_bytes, mix_pool_bytes_nolock,
 );
 
 TRACE_EVENT(credit_entropy_bits,
-	TP_PROTO(int bits, int entropy_count, unsigned long IP),
+	TP_PROTO(size_t bits, size_t entropy_count, unsigned long IP),
 
 	TP_ARGS(bits, entropy_count, IP),
 
 	TP_STRUCT__entry(
-		__field(	  int,	bits			)
-		__field(	  int,	entropy_count		)
+		__field(size_t,		bits			)
+		__field(size_t,		entropy_count		)
 		__field(unsigned long,	IP			)
 	),
 
@@ -75,34 +75,34 @@ TRACE_EVENT(credit_entropy_bits,
 		__entry->IP		= IP;
 	),
 
-	TP_printk("input pool: bits %d entropy_count %d caller %pS",
+	TP_printk("input pool: bits %zu entropy_count %zu caller %pS",
 		  __entry->bits, __entry->entropy_count, (void *)__entry->IP)
 );
 
 TRACE_EVENT(add_input_randomness,
-	TP_PROTO(int input_bits),
+	TP_PROTO(size_t input_bits),
 
 	TP_ARGS(input_bits),
 
 	TP_STRUCT__entry(
-		__field(	  int,	input_bits		)
+		__field(size_t,	input_bits		)
 	),
 
 	TP_fast_assign(
 		__entry->input_bits	= input_bits;
 	),
 
-	TP_printk("input_pool_bits %d", __entry->input_bits)
+	TP_printk("input_pool_bits %zu", __entry->input_bits)
 );
 
 TRACE_EVENT(add_disk_randomness,
-	TP_PROTO(dev_t dev, int input_bits),
+	TP_PROTO(dev_t dev, size_t input_bits),
 
 	TP_ARGS(dev, input_bits),
 
 	TP_STRUCT__entry(
-		__field(	dev_t,	dev			)
-		__field(	  int,	input_bits		)
+		__field(dev_t,		dev			)
+		__field(size_t,		input_bits		)
 	),
 
 	TP_fast_assign(
@@ -110,17 +110,17 @@ TRACE_EVENT(add_disk_randomness,
 		__entry->input_bits	= input_bits;
 	),
 
-	TP_printk("dev %d,%d input_pool_bits %d", MAJOR(__entry->dev),
+	TP_printk("dev %d,%d input_pool_bits %zu", MAJOR(__entry->dev),
 		  MINOR(__entry->dev), __entry->input_bits)
 );
 
 DECLARE_EVENT_CLASS(random__get_random_bytes,
-	TP_PROTO(int nbytes, unsigned long IP),
+	TP_PROTO(size_t nbytes, unsigned long IP),
 
 	TP_ARGS(nbytes, IP),
 
 	TP_STRUCT__entry(
-		__field(	  int,	nbytes			)
+		__field(size_t,		nbytes			)
 		__field(unsigned long,	IP			)
 	),
 
@@ -129,29 +129,29 @@ DECLARE_EVENT_CLASS(random__get_random_bytes,
 		__entry->IP		= IP;
 	),
 
-	TP_printk("nbytes %d caller %pS", __entry->nbytes, (void *)__entry->IP)
+	TP_printk("nbytes %zu caller %pS", __entry->nbytes, (void *)__entry->IP)
 );
 
 DEFINE_EVENT(random__get_random_bytes, get_random_bytes,
-	TP_PROTO(int nbytes, unsigned long IP),
+	TP_PROTO(size_t nbytes, unsigned long IP),
 
 	TP_ARGS(nbytes, IP)
 );
 
 DEFINE_EVENT(random__get_random_bytes, get_random_bytes_arch,
-	TP_PROTO(int nbytes, unsigned long IP),
+	TP_PROTO(size_t nbytes, unsigned long IP),
 
 	TP_ARGS(nbytes, IP)
 );
 
 DECLARE_EVENT_CLASS(random__extract_entropy,
-	TP_PROTO(int nbytes, int entropy_count),
+	TP_PROTO(size_t nbytes, size_t entropy_count),
 
 	TP_ARGS(nbytes, entropy_count),
 
 	TP_STRUCT__entry(
-		__field(	  int,	nbytes			)
-		__field(	  int,	entropy_count		)
+		__field(  size_t,	nbytes			)
+		__field(  size_t,	entropy_count		)
 	),
 
 	TP_fast_assign(
@@ -159,37 +159,34 @@ DECLARE_EVENT_CLASS(random__extract_entropy,
 		__entry->entropy_count	= entropy_count;
 	),
 
-	TP_printk("input pool: nbytes %d entropy_count %d",
+	TP_printk("input pool: nbytes %zu entropy_count %zu",
 		  __entry->nbytes, __entry->entropy_count)
 );
 
 
 DEFINE_EVENT(random__extract_entropy, extract_entropy,
-	TP_PROTO(int nbytes, int entropy_count),
+	TP_PROTO(size_t nbytes, size_t entropy_count),
 
 	TP_ARGS(nbytes, entropy_count)
 );
 
 TRACE_EVENT(urandom_read,
-	TP_PROTO(int got_bits, int pool_left, int input_left),
+	TP_PROTO(size_t nbytes, size_t entropy_count),
 
-	TP_ARGS(got_bits, pool_left, input_left),
+	TP_ARGS(nbytes, entropy_count),
 
 	TP_STRUCT__entry(
-		__field(	  int,	got_bits		)
-		__field(	  int,	pool_left		)
-		__field(	  int,	input_left		)
+		__field( size_t,	nbytes		)
+		__field( size_t,	entropy_count	)
 	),
 
 	TP_fast_assign(
-		__entry->got_bits	= got_bits;
-		__entry->pool_left	= pool_left;
-		__entry->input_left	= input_left;
+		__entry->nbytes		= nbytes;
+		__entry->entropy_count	= entropy_count;
 	),
 
-	TP_printk("got_bits %d nonblocking_pool_entropy_left %d "
-		  "input_entropy_left %d", __entry->got_bits,
-		  __entry->pool_left, __entry->input_left)
+	TP_printk("reading: nbytes %zu entropy_count %zu",
+		  __entry->nbytes, __entry->entropy_count)
 );
 
 #endif /* _TRACE_RANDOM_H */