[PATCH RESEND v7 3/3] arm64: kexec_file: add rng-seed support - Hsin-Yi Wang

From: Hsin-Yi Wang <hsinyi@chromium.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Rob Herring <robh+dt@kernel.org>,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	Frank Rowand <frowand.list@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Mike Rapoport <rppt@linux.ibm.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Miles Chen <miles.chen@mediatek.com>,
	Hsin-Yi Wang <hsinyi@chromium.org>,
	James Morse <james.morse@arm.com>,
	Andrew Murray <andrew.murray@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Jun Yao <yaojun8558363@gmail.com>, Yu Zhao <yuzhao@google.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Laura Abbott <labbott@redhat.com>,
	Stephen Boyd <swboyd@chromium.org>,
	Kees Cook <keescook@chromium.org>
Subject: [PATCH RESEND v7 3/3] arm64: kexec_file: add rng-seed support
Date: Fri,  9 Aug 2019 01:38:07 +0800	[thread overview]
Message-ID: <20190808173803.1146-4-hsinyi@chromium.org> (raw)
In-Reply-To: <20190808173803.1146-1-hsinyi@chromium.org>

Adding "rng-seed" to dtb. It's fine to add this property if original
fdt doesn't contain it. Since original seed will be wiped after
read, so use a default size 128 bytes here.

Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
---
 arch/arm64/kernel/machine_kexec_file.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
index ba78ee7ca990..7b08bf9499b6 100644
--- a/arch/arm64/kernel/machine_kexec_file.c
+++ b/arch/arm64/kernel/machine_kexec_file.c
@@ -27,6 +27,8 @@
 #define FDT_PROP_INITRD_END	"linux,initrd-end"
 #define FDT_PROP_BOOTARGS	"bootargs"
 #define FDT_PROP_KASLR_SEED	"kaslr-seed"
+#define FDT_PROP_RNG_SEED	"rng-seed"
+#define RNG_SEED_SIZE		128
 
 const struct kexec_file_ops * const kexec_file_loaders[] = {
 	&kexec_image_ops,
@@ -102,6 +104,19 @@ static int setup_dtb(struct kimage *image,
 				FDT_PROP_KASLR_SEED);
 	}
 
+	/* add rng-seed */
+	if (rng_is_initialized()) {
+		u8 rng_seed[RNG_SEED_SIZE];
+		get_random_bytes(rng_seed, RNG_SEED_SIZE);
+		ret = fdt_setprop(dtb, off, FDT_PROP_RNG_SEED, rng_seed,
+				RNG_SEED_SIZE);
+		if (ret)
+			goto out;
+	} else {
+		pr_notice("RNG is not initialised: omitting \"%s\" property\n",
+				FDT_PROP_RNG_SEED);
+	}
+
 out:
 	if (ret)
 		return (ret == -FDT_ERR_NOSPACE) ? -ENOMEM : -EINVAL;
@@ -110,7 +125,8 @@ static int setup_dtb(struct kimage *image,
 }
 
 /*
- * More space needed so that we can add initrd, bootargs and kaslr-seed.
+ * More space needed so that we can add initrd, bootargs, kaslr-seed, and
+ * rng-seed.
  */
 #define DTB_EXTRA_SPACE 0x1000
 
-- 
2.20.1

