On Mon, May 13, 2019 at 08:38:18AM +0800, Hsin-Yi Wang wrote:
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);
Please fix the indentation.
- /* break now */ return 1;
}
2.20.1