[PATCH v3 2/3] efi: qemu: arm64: Add efi_rng_protocol implementation for the platform
Sughosh Ganu
sughosh.ganu at linaro.org
Fri Dec 27 15:26:15 CET 2019
Add support for the EFI_RNG_PROTOCOL routines for the qemu arm64
platform. EFI_RNG_PROTOCOL is an uefi boottime service which is
invoked by the efi stub in the kernel for getting random seed for
kaslr.
The routines are platform specific, and use the virtio-rng device on
the platform to get random data.
The feature can be enabled through the following config
CONFIG_EFI_RNG_PROTOCOL
Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
---
Changes since V2:
* Based on review comments from Heinrich Schuchardt, the rng drivers
read all the bytes requested in the individual
drivers. Corresponding changes made in getrng routine to remove the
loop to read the bytes requested, since that would be handled in the
drivers.
board/emulation/qemu-arm/qemu-arm.c | 41 +++++++++++++++++++
include/efi_rng.h | 32 +++++++++++++++
lib/efi_loader/Kconfig | 8 ++++
lib/efi_loader/Makefile | 1 +
lib/efi_loader/efi_rng.c | 80 +++++++++++++++++++++++++++++++++++++
5 files changed, 162 insertions(+)
create mode 100644 include/efi_rng.h
create mode 100644 lib/efi_loader/efi_rng.c
diff --git a/board/emulation/qemu-arm/qemu-arm.c b/board/emulation/qemu-arm/qemu-arm.c
index e1f4709..1dcf830 100644
--- a/board/emulation/qemu-arm/qemu-arm.c
+++ b/board/emulation/qemu-arm/qemu-arm.c
@@ -91,3 +91,44 @@ void *board_fdt_blob_setup(void)
/* QEMU loads a generated DTB for us at the start of RAM. */
return (void *)CONFIG_SYS_SDRAM_BASE;
}
+
+#if defined(CONFIG_EFI_RNG_PROTOCOL)
+#include <efi_loader.h>
+#include <efi_rng.h>
+
+#include <dm/device-internal.h>
+
+efi_status_t platform_get_rng_device(struct udevice **dev)
+{
+ int ret;
+ efi_status_t status = EFI_DEVICE_ERROR;
+ struct udevice *bus, *devp;
+
+ for (uclass_first_device(UCLASS_VIRTIO, &bus); bus;
+ uclass_next_device(&bus)) {
+ for (device_find_first_child(bus, &devp); devp; device_find_next_child(&devp)) {
+ if (device_get_uclass_id(devp) == UCLASS_RNG) {
+ *dev = devp;
+ status = EFI_SUCCESS;
+ break;
+ }
+ }
+ }
+
+ if (status != EFI_SUCCESS) {
+ debug("No rng device found\n");
+ return EFI_DEVICE_ERROR;
+ }
+
+ if (*dev) {
+ ret = device_probe(*dev);
+ if (ret)
+ return EFI_DEVICE_ERROR;
+ } else {
+ debug("Couldn't get child device\n");
+ return EFI_DEVICE_ERROR;
+ }
+
+ return EFI_SUCCESS;
+}
+#endif /* CONFIG_EFI_RNG_PROTOCOL */
diff --git a/include/efi_rng.h b/include/efi_rng.h
new file mode 100644
index 0000000..a46e66d
--- /dev/null
+++ b/include/efi_rng.h
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2019, Linaro Limited
+ */
+
+#if !defined _EFI_RNG_H_
+#define _EFI_RNG_H_
+
+#include <efi.h>
+#include <efi_api.h>
+
+/* EFI random number generation protocol related GUID definitions */
+#define EFI_RNG_PROTOCOL_GUID \
+ EFI_GUID(0x3152bca5, 0xeade, 0x433d, 0x86, 0x2e, \
+ 0xc0, 0x1c, 0xdc, 0x29, 0x1f, 0x44)
+
+#define EFI_RNG_ALGORITHM_RAW \
+ EFI_GUID(0xe43176d7, 0xb6e8, 0x4827, 0xb7, 0x84, \
+ 0x7f, 0xfd, 0xc4, 0xb6, 0x85, 0x61)
+
+struct efi_rng_protocol {
+ efi_status_t (EFIAPI *get_info)(struct efi_rng_protocol *protocol,
+ efi_uintn_t *rng_algorithm_list_size,
+ efi_guid_t *rng_algorithm_list);
+ efi_status_t (EFIAPI *get_rng)(struct efi_rng_protocol *protocol,
+ efi_guid_t *rng_algorithm,
+ efi_uintn_t rng_value_length, uint8_t *rng_value);
+};
+
+efi_status_t platform_get_rng_device(struct udevice **dev);
+
+#endif /* _EFI_RNG_H_ */
diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
index 21ef440..24dde6f 100644
--- a/lib/efi_loader/Kconfig
+++ b/lib/efi_loader/Kconfig
@@ -120,4 +120,12 @@ config EFI_GRUB_ARM32_WORKAROUND
GRUB prior to version 2.04 requires U-Boot to disable caches. This
workaround currently is also needed on systems with caches that
cannot be managed via CP15.
+
+config EFI_RNG_PROTOCOL
+ bool "EFI_RNG_PROTOCOL support"
+ depends on DM_RNG
+ help
+ "Support for EFI_RNG_PROTOCOL implementation. Uses the rng
+ device on the platform"
+
endif
diff --git a/lib/efi_loader/Makefile b/lib/efi_loader/Makefile
index 7db4060..04dc864 100644
--- a/lib/efi_loader/Makefile
+++ b/lib/efi_loader/Makefile
@@ -42,3 +42,4 @@ obj-$(CONFIG_PARTITIONS) += efi_disk.o
obj-$(CONFIG_NET) += efi_net.o
obj-$(CONFIG_GENERATE_ACPI_TABLE) += efi_acpi.o
obj-$(CONFIG_GENERATE_SMBIOS_TABLE) += efi_smbios.o
+obj-$(CONFIG_EFI_RNG_PROTOCOL) += efi_rng.o
diff --git a/lib/efi_loader/efi_rng.c b/lib/efi_loader/efi_rng.c
new file mode 100644
index 0000000..eb91aa7
--- /dev/null
+++ b/lib/efi_loader/efi_rng.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2019, Linaro Limited
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <efi_loader.h>
+#include <efi_rng.h>
+#include <rng.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+static efi_status_t EFIAPI rng_getinfo(struct efi_rng_protocol *this,
+ efi_uintn_t *rng_algorithm_list_size,
+ efi_guid_t *rng_algorithm_list)
+{
+ efi_guid_t rng_algo_guid = EFI_RNG_ALGORITHM_RAW;
+
+ EFI_ENTRY("%p, %p, %p", this, rng_algorithm_list_size,
+ rng_algorithm_list);
+
+ if (!this || !rng_algorithm_list_size)
+ return EFI_INVALID_PARAMETER;
+
+ if (!rng_algorithm_list ||
+ *rng_algorithm_list_size < sizeof(*rng_algorithm_list)) {
+ *rng_algorithm_list_size = sizeof(*rng_algorithm_list);
+ return EFI_BUFFER_TOO_SMALL;
+ }
+
+ /*
+ * For now, use EFI_RNG_ALGORITHM_RAW as the default
+ * algorithm. If a new algorithm gets added in the
+ * future through a Kconfig, rng_algo_guid will be set
+ * based on that Kconfig option
+ */
+ *rng_algorithm_list_size = sizeof(*rng_algorithm_list);
+ guidcpy(rng_algorithm_list, &rng_algo_guid);
+
+ return EFI_EXIT(EFI_SUCCESS);
+}
+
+static efi_status_t EFIAPI getrng(struct efi_rng_protocol *this,
+ efi_guid_t *rng_algorithm,
+ efi_uintn_t rng_value_length,
+ uint8_t *rng_value)
+{
+ int ret;
+ struct udevice *dev;
+ const efi_guid_t rng_raw_guid = EFI_RNG_ALGORITHM_RAW;
+
+ EFI_ENTRY("%p, %p, %zu, %p", this, rng_algorithm, rng_value_length,
+ rng_value);
+
+ if (!this || !rng_value || !rng_value_length)
+ return EFI_INVALID_PARAMETER;
+
+ if (rng_algorithm) {
+ if (guidcmp(rng_algorithm, &rng_raw_guid))
+ return EFI_UNSUPPORTED;
+ }
+
+ ret = platform_get_rng_device(&dev);
+ if (ret != EFI_SUCCESS)
+ return EFI_UNSUPPORTED;
+
+ ret = dm_rng_read(dev, rng_value, rng_value_length);
+ if (ret < 0) {
+ debug("Rng device read failed\n");
+ return EFI_DEVICE_ERROR;
+ }
+
+ return EFI_EXIT(EFI_SUCCESS);
+}
+
+const struct efi_rng_protocol efi_rng_protocol = {
+ .get_info = rng_getinfo,
+ .get_rng = getrng,
+};
--
2.7.4
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