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.
Obtain of_fdt_crc32 for CRC check after early_init_dt_scan_nodes(),
since early_init_dt_scan_chosen() would modify fdt to erase rng-seed.
Signed-off-by: Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx>
Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
---
Change from v7:
obtain of_fdt_crc32 after early_init_dt_scan_nodes().
---
drivers/of/fdt.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 9cdf14b9aaab..97a75996993c 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>
@@ -1044,6 +1045,7 @@ 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);
@@ -1078,6 +1080,14 @@ 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) {
+ add_device_randomness(rng_seed, l);
+
+ /* try to clear seed so it won't be found. */
+ fdt_nop_property(initial_boot_params, node, "rng-seed");
+ }
+
/* break now */
return 1;
}
@@ -1166,8 +1176,6 @@ bool __init early_init_dt_verify(void *params)
/* Setup flat device-tree pointer */
initial_boot_params = params;
- of_fdt_crc32 = crc32_be(~0, initial_boot_params,
- fdt_totalsize(initial_boot_params));
return true;
}
@@ -1197,6 +1205,8 @@ bool __init early_init_dt_scan(void *params)
return false;
early_init_dt_scan_nodes();
+ of_fdt_crc32 = crc32_be(~0, initial_boot_params,
+ fdt_totalsize(initial_boot_params));
return true;
}
--
2.20.1
