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* [PATCH v2 1/2] fdt: add support for rng-seed
@ 2019-05-13  0:38 Hsin-Yi Wang
  2019-05-13  0:38 ` [PATCH v2 2/2] amr64: map FDT as RW for early_init_dt_scan() Hsin-Yi Wang
                   ` (2 more replies)
  0 siblings, 3 replies; 14+ messages in thread
From: Hsin-Yi Wang @ 2019-05-13  0:38 UTC (permalink / raw)
  To: linux-arm-kernel
  Cc: Rob Herring, Mark Rutland, Frank Rowand, Hsin-Yi Wang,
	devicetree, linux-kernel, Stephen Boyd, Kees Cook,
	Rasmus Villemoes, boot-architecture, Catalin Marinas,
	Will Deacon, Andrew Morton, Mike Rapoport, Michal Hocko,
	Ard Biesheuvel, Miles Chen, James Morse, Andrew Murray

Introducing a chosen node, rng-seed, which is an entropy that can be
passed to kernel called very early to increase initial device
randomness. Bootloader should provide this entropy and the value is
read from /chosen/rng-seed in DT.

Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
---
change log:
v1->v2:
* call function in early_init_dt_scan_chosen
* will add doc to devicetree-org/dt-schema on github if this is accepted
---
 Documentation/devicetree/bindings/chosen.txt | 14 ++++++++++++++
 drivers/of/fdt.c                             | 11 +++++++++++
 2 files changed, 25 insertions(+)

diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt
index 45e79172a646..fef5c82672dc 100644
--- a/Documentation/devicetree/bindings/chosen.txt
+++ b/Documentation/devicetree/bindings/chosen.txt
@@ -28,6 +28,20 @@ mode) when EFI_RNG_PROTOCOL is supported, it will be overwritten by
 the Linux EFI stub (which will populate the property itself, using
 EFI_RNG_PROTOCOL).
 
+rng-seed
+-----------
+
+This property served as an entropy to add device randomness. It is parsed
+as a byte array, e.g.
+
+/ {
+	chosen {
+		rng-seed = <0x31 0x95 0x1b 0x3c 0xc9 0xfa 0xb3 ...>;
+	};
+};
+
+This random value should be provided by bootloader.
+
 stdout-path
 -----------
 
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index de893c9616a1..96ea5eba9dd5 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -24,6 +24,7 @@
 #include <linux/debugfs.h>
 #include <linux/serial_core.h>
 #include <linux/sysfs.h>
+#include <linux/random.h>
 
 #include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
 #include <asm/page.h>
@@ -1079,6 +1080,7 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 {
 	int l;
 	const char *p;
+	const void *rng_seed;
 
 	pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname);
 
@@ -1113,6 +1115,15 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 
 	pr_debug("Command line is: %s\n", (char*)data);
 
+	rng_seed = of_get_flat_dt_prop(node, "rng-seed", &l);
+	if (!rng_seed || l == 0)
+		return 1;
+
+	/* try to clear seed so it won't be found. */
+        fdt_nop_property(initial_boot_params, node, "rng-seed");
+
+        add_device_randomness(rng_seed, l);
+
 	/* break now */
 	return 1;
 }
-- 
2.20.1


^ permalink raw reply	[flat|nested] 14+ messages in thread

end of thread, other threads:[~2019-05-16 11:07 UTC | newest]

Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-05-13  0:38 [PATCH v2 1/2] fdt: add support for rng-seed Hsin-Yi Wang
2019-05-13  0:38 ` [PATCH v2 2/2] amr64: map FDT as RW for early_init_dt_scan() Hsin-Yi Wang
2019-05-13  8:58   ` Mike Rapoport
2019-05-13 11:14     ` Hsin-Yi Wang
2019-05-14 15:42       ` Mike Rapoport
2019-05-15 10:24         ` Hsin-Yi Wang
2019-05-15 20:11           ` Ard Biesheuvel
2019-05-16 11:07             ` Mike Rapoport
2019-05-14 21:05       ` Stephen Boyd
2019-05-15  5:00         ` Mike Rapoport
2019-05-15 10:34           ` Hsin-Yi Wang
2019-05-13  8:42 ` [PATCH v2 1/2] fdt: add support for rng-seed Mike Rapoport
2019-05-13 13:14 ` Rob Herring
2019-05-15  9:07   ` Hsin-Yi Wang

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