CVS commit: src/sys/crypto/cprng_fast

[Taylor R Campbell]

Module Name:src
Committed By:   riastradh
Date:   Sat Aug  5 11:39:18 UTC 2023

Modified Files:
src/sys/crypto/cprng_fast: cprng_fast.c

Log Message:
cprng_fast(9): Drop and retake percpu reference across cprng_strong.

cprng_strong may sleep on an adaptive lock (via entropy_extract),
which invalidates percpu(9) references.

Discovered by stumbling upon this panic in a test run:

panic: kernel diagnostic assertion "(cprng == percpu_getref(cprng_fast_percpu)) 
&& (percpu_putref(cprng_fast_percpu), true)" failed: file 
"/home/riastradh/netbsd/current/src/sys/rump/librump/rumpkern/../../../crypto/cprng_fast/cprng_fast.c",
 line 117

XXX pullup-10


To generate a diff of this commit:
cvs rdiff -u -r1.18 -r1.19 src/sys/crypto/cprng_fast/cprng_fast.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

Modified files:

Index: src/sys/crypto/cprng_fast/cprng_fast.c
diff -u src/sys/crypto/cprng_fast/cprng_fast.c:1.18 src/sys/crypto/cprng_fast/cprng_fast.c:1.19
--- src/sys/crypto/cprng_fast/cprng_fast.c:1.18	Thu Sep  1 18:32:25 2022
+++ src/sys/crypto/cprng_fast/cprng_fast.c	Sat Aug  5 11:39:18 2023
@@ -1,4 +1,4 @@
-/*	$NetBSD: cprng_fast.c,v 1.18 2022/09/01 18:32:25 riastradh Exp $	*/
+/*	$NetBSD: cprng_fast.c,v 1.19 2023/08/05 11:39:18 riastradh Exp $	*/
 
 /*-
  * Copyright (c) 2014 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include 
-__KERNEL_RCSID(0, "$NetBSD: cprng_fast.c,v 1.18 2022/09/01 18:32:25 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: cprng_fast.c,v 1.19 2023/08/05 11:39:18 riastradh Exp $");
 
 #include 
 #include 
@@ -58,7 +58,7 @@ struct cprng_fast {
 };
 
 static void	cprng_fast_init_cpu(void *, void *, struct cpu_info *);
-static void	cprng_fast_reseed(struct cprng_fast *);
+static void	cprng_fast_reseed(struct cprng_fast **, unsigned);
 
 static void	cprng_fast_seed(struct cprng_fast *, const void *);
 static void	cprng_fast_buf(struct cprng_fast *, void *, unsigned);
@@ -93,6 +93,7 @@ static int
 cprng_fast_get(struct cprng_fast **cprngp)
 {
 	struct cprng_fast *cprng;
+	unsigned epoch;
 	int s;
 
 	KASSERT(!cpu_intr_p());
@@ -101,9 +102,10 @@ cprng_fast_get(struct cprng_fast **cprng
 	*cprngp = cprng = percpu_getref(cprng_fast_percpu);
 	s = splsoftserial();
 
-	if (__predict_false(cprng->epoch != entropy_epoch())) {
+	epoch = entropy_epoch();
+	if (__predict_false(cprng->epoch != epoch)) {
 		splx(s);
-		cprng_fast_reseed(cprng);
+		cprng_fast_reseed(cprngp, epoch);
 		s = splsoftserial();
 	}
 
@@ -121,13 +123,25 @@ cprng_fast_put(struct cprng_fast *cprng,
 }
 
 static void
-cprng_fast_reseed(struct cprng_fast *cprng)
+cprng_fast_reseed(struct cprng_fast **cprngp, unsigned epoch)
 {
-	unsigned epoch = entropy_epoch();
+	struct cprng_fast *cprng;
 	uint8_t seed[CPRNG_FAST_SEED_BYTES];
 	int s;
 
+	/*
+	 * Drop the percpu(9) reference to extract a fresh seed from
+	 * the entropy pool.  cprng_strong may sleep on an adaptive
+	 * lock, which invalidates our percpu(9) reference.
+	 *
+	 * This may race with reseeding in another thread, which is no
+	 * big deal -- worst case, we rewind the entropy epoch here and
+	 * cause the next caller to reseed again, and in the end we
+	 * just reseed a couple more times than necessary.
+	 */
+	percpu_putref(cprng_fast_percpu);
 	cprng_strong(kern_cprng, seed, sizeof(seed), 0);
+	*cprngp = cprng = percpu_getref(cprng_fast_percpu);
 
 	s = splsoftserial();
 	cprng_fast_seed(cprng, seed);

CVS commit: src/sys/crypto/cprng_fast

[Taylor R Campbell]

Module Name:src
Committed By:   riastradh
Date:   Sat Aug  5 11:39:18 UTC 2023

Modified Files:
src/sys/crypto/cprng_fast: cprng_fast.c

Log Message:
cprng_fast(9): Drop and retake percpu reference across cprng_strong.

cprng_strong may sleep on an adaptive lock (via entropy_extract),
which invalidates percpu(9) references.

Discovered by stumbling upon this panic in a test run:

panic: kernel diagnostic assertion "(cprng == percpu_getref(cprng_fast_percpu)) 
&& (percpu_putref(cprng_fast_percpu), true)" failed: file 
"/home/riastradh/netbsd/current/src/sys/rump/librump/rumpkern/../../../crypto/cprng_fast/cprng_fast.c",
 line 117

XXX pullup-10


To generate a diff of this commit:
cvs rdiff -u -r1.18 -r1.19 src/sys/crypto/cprng_fast/cprng_fast.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

CVS commit: src/sys/crypto/cprng_fast

[Taylor R Campbell]

Module Name:src
Committed By:   riastradh
Date:   Thu Sep  1 18:32:25 UTC 2022

Modified Files:
src/sys/crypto/cprng_fast: cprng_fast.c

Log Message:
cprng_fast(9): Assert not in pserialize read section.

This may sleep to take the global entropy lock in case it needs to be
reseeded.  If that happens we can't be in a pserialize read section.


To generate a diff of this commit:
cvs rdiff -u -r1.17 -r1.18 src/sys/crypto/cprng_fast/cprng_fast.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

Modified files:

Index: src/sys/crypto/cprng_fast/cprng_fast.c
diff -u src/sys/crypto/cprng_fast/cprng_fast.c:1.17 src/sys/crypto/cprng_fast/cprng_fast.c:1.18
--- src/sys/crypto/cprng_fast/cprng_fast.c:1.17	Wed Jun  1 15:44:37 2022
+++ src/sys/crypto/cprng_fast/cprng_fast.c	Thu Sep  1 18:32:25 2022
@@ -1,4 +1,4 @@
-/*	$NetBSD: cprng_fast.c,v 1.17 2022/06/01 15:44:37 riastradh Exp $	*/
+/*	$NetBSD: cprng_fast.c,v 1.18 2022/09/01 18:32:25 riastradh Exp $	*/
 
 /*-
  * Copyright (c) 2014 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include 
-__KERNEL_RCSID(0, "$NetBSD: cprng_fast.c,v 1.17 2022/06/01 15:44:37 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: cprng_fast.c,v 1.18 2022/09/01 18:32:25 riastradh Exp $");
 
 #include 
 #include 
@@ -41,6 +41,7 @@ __KERNEL_RCSID(0, "$NetBSD: cprng_fast.c
 #include 
 #include 
 #include 
+#include 
 
 #include 
 
@@ -95,6 +96,7 @@ cprng_fast_get(struct cprng_fast **cprng
 	int s;
 
 	KASSERT(!cpu_intr_p());
+	KASSERT(pserialize_not_in_read_section());
 
 	*cprngp = cprng = percpu_getref(cprng_fast_percpu);
 	s = splsoftserial();

CVS commit: src/sys/crypto/cprng_fast

[Taylor R Campbell]

Module Name:src
Committed By:   riastradh
Date:   Thu Sep  1 18:32:25 UTC 2022

Modified Files:
src/sys/crypto/cprng_fast: cprng_fast.c

Log Message:
cprng_fast(9): Assert not in pserialize read section.

This may sleep to take the global entropy lock in case it needs to be
reseeded.  If that happens we can't be in a pserialize read section.


To generate a diff of this commit:
cvs rdiff -u -r1.17 -r1.18 src/sys/crypto/cprng_fast/cprng_fast.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

CVS commit: src/sys/crypto/cprng_fast

[Taylor R Campbell]

Module Name:src
Committed By:   riastradh
Date:   Wed Jun  1 15:44:37 UTC 2022

Modified Files:
src/sys/crypto/cprng_fast: cprng_fast.c

Log Message:
cprng(9): cprng_fast is no longer used from interrupt context.

Rip out logic to defer reseeding to softint.


To generate a diff of this commit:
cvs rdiff -u -r1.16 -r1.17 src/sys/crypto/cprng_fast/cprng_fast.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

Modified files:

Index: src/sys/crypto/cprng_fast/cprng_fast.c
diff -u src/sys/crypto/cprng_fast/cprng_fast.c:1.16 src/sys/crypto/cprng_fast/cprng_fast.c:1.17
--- src/sys/crypto/cprng_fast/cprng_fast.c:1.16	Tue Jul 28 20:15:07 2020
+++ src/sys/crypto/cprng_fast/cprng_fast.c	Wed Jun  1 15:44:37 2022
@@ -1,4 +1,4 @@
-/*	$NetBSD: cprng_fast.c,v 1.16 2020/07/28 20:15:07 riastradh Exp $	*/
+/*	$NetBSD: cprng_fast.c,v 1.17 2022/06/01 15:44:37 riastradh Exp $	*/
 
 /*-
  * Copyright (c) 2014 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include 
-__KERNEL_RCSID(0, "$NetBSD: cprng_fast.c,v 1.16 2020/07/28 20:15:07 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: cprng_fast.c,v 1.17 2022/06/01 15:44:37 riastradh Exp $");
 
 #include 
 #include 
@@ -39,7 +39,6 @@ __KERNEL_RCSID(0, "$NetBSD: cprng_fast.c
 #include 
 #include 
 #include 
-#include 
 #include 
 #include 
 
@@ -58,8 +57,7 @@ struct cprng_fast {
 };
 
 static void	cprng_fast_init_cpu(void *, void *, struct cpu_info *);
-static void	cprng_fast_schedule_reseed(struct cprng_fast *);
-static void	cprng_fast_intr(void *);
+static void	cprng_fast_reseed(struct cprng_fast *);
 
 static void	cprng_fast_seed(struct cprng_fast *, const void *);
 static void	cprng_fast_buf(struct cprng_fast *, void *, unsigned);
@@ -68,7 +66,6 @@ static void	cprng_fast_buf_short(void *,
 static void	cprng_fast_buf_long(void *, size_t);
 
 static percpu_t	*cprng_fast_percpu	__read_mostly;
-static void	*cprng_fast_softint	__read_mostly;
 
 void
 cprng_fast_init(void)
@@ -76,20 +73,14 @@ cprng_fast_init(void)
 
 	cprng_fast_percpu = percpu_create(sizeof(struct cprng_fast),
 	cprng_fast_init_cpu, NULL, NULL);
-	cprng_fast_softint = softint_establish(SOFTINT_SERIAL|SOFTINT_MPSAFE,
-	_fast_intr, NULL);
 }
 
 static void
 cprng_fast_init_cpu(void *p, void *arg __unused, struct cpu_info *ci)
 {
 	struct cprng_fast *const cprng = p;
-	uint8_t seed[CPRNG_FAST_SEED_BYTES];
 
-	cprng->epoch = entropy_epoch();
-	cprng_strong(kern_cprng, seed, sizeof seed, 0);
-	cprng_fast_seed(cprng, seed);
-	(void)explicit_memset(seed, 0, sizeof seed);
+	cprng->epoch = 0;
 
 	cprng->reseed_evcnt = kmem_alloc(sizeof(*cprng->reseed_evcnt),
 	KM_SLEEP);
@@ -103,11 +94,16 @@ cprng_fast_get(struct cprng_fast **cprng
 	struct cprng_fast *cprng;
 	int s;
 
+	KASSERT(!cpu_intr_p());
+
 	*cprngp = cprng = percpu_getref(cprng_fast_percpu);
-	s = splvm();
+	s = splsoftserial();
 
-	if (__predict_false(cprng->epoch != entropy_epoch()))
-		cprng_fast_schedule_reseed(cprng);
+	if (__predict_false(cprng->epoch != entropy_epoch())) {
+		splx(s);
+		cprng_fast_reseed(cprng);
+		s = splsoftserial();
+	}
 
 	return s;
 }
@@ -123,29 +119,19 @@ cprng_fast_put(struct cprng_fast *cprng,
 }
 
 static void
-cprng_fast_schedule_reseed(struct cprng_fast *cprng __unused)
-{
-
-	softint_schedule(cprng_fast_softint);
-}
-
-static void
-cprng_fast_intr(void *cookie __unused)
+cprng_fast_reseed(struct cprng_fast *cprng)
 {
 	unsigned epoch = entropy_epoch();
-	struct cprng_fast *cprng;
 	uint8_t seed[CPRNG_FAST_SEED_BYTES];
 	int s;
 
 	cprng_strong(kern_cprng, seed, sizeof(seed), 0);
 
-	cprng = percpu_getref(cprng_fast_percpu);
-	s = splvm();
+	s = splsoftserial();
 	cprng_fast_seed(cprng, seed);
 	cprng->epoch = epoch;
 	cprng->reseed_evcnt->ev_count++;
 	splx(s);
-	percpu_putref(cprng_fast_percpu);
 
 	explicit_memset(seed, 0, sizeof(seed));
 }

CVS commit: src/sys/crypto/cprng_fast

[Taylor R Campbell]

Module Name:src
Committed By:   riastradh
Date:   Wed Jun  1 15:44:37 UTC 2022

Modified Files:
src/sys/crypto/cprng_fast: cprng_fast.c

Log Message:
cprng(9): cprng_fast is no longer used from interrupt context.

Rip out logic to defer reseeding to softint.


To generate a diff of this commit:
cvs rdiff -u -r1.16 -r1.17 src/sys/crypto/cprng_fast/cprng_fast.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.