linux-kernel - [PATCH 1/1] efi/libstub: describe RNG functions

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Date:   Fri, 21 Feb 2020 12:47:16 +0100
From:   Heinrich Schuchardt <xypron.glpk@....de>
To:     Ard Biesheuvel <ardb@...nel.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        Dan Williams <dan.j.williams@...el.com>,
        Hans de Goede <hdegoede@...hat.com>,
        linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Heinrich Schuchardt <xypron.glpk@....de>
Subject: [PATCH 1/1] efi/libstub: describe RNG functions

Provide descriptions for the functions invoking the EFI_RNG_PROTOCOL.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@....de>
---
 drivers/firmware/efi/libstub/random.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/firmware/efi/libstub/random.c b/drivers/firmware/efi/libstub/random.c
index 21e7e9325219..24aa37535372 100644
--- a/drivers/firmware/efi/libstub/random.c
+++ b/drivers/firmware/efi/libstub/random.c
@@ -25,6 +25,17 @@ union efi_rng_protocol {
 	} mixed_mode;
 };

+/**
+ * efi_get_random_bytes() - fill a buffer with random bytes
+ * @size:	size of the buffer
+ * @out:	caller allocated buffer to receive the random bytes
+ *
+ * The call will fail if either the firmware does not implement the
+ * EFI_RNG_PROTOCOL or there are not enough random bytes available to fill
+ * the buffer.
+ *
+ * Return:	status code
+ */
 efi_status_t efi_get_random_bytes(unsigned long size, u8 *out)
 {
 	efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID;
@@ -38,6 +49,19 @@ efi_status_t efi_get_random_bytes(unsigned long size, u8 *out)
 	return efi_call_proto(rng, get_rng, NULL, size, out);
 }

+/**
+ * efi_random_get_seed() - provide random seed as configuration table
+ *
+ * The EFI_RNG_PROTOCOL is used to read random bytes. These random bytes are
+ * saved as a configuration table which can be used as entropy by the kernel
+ * for the initialization of its pseudo random number generator.
+ *
+ * If the EFI_RNG_PROTOCOL is not available or there are not enough random bytes
+ * available, the configuration table will not be installed and an error code
+ * will be returned.
+ *
+ * Return:	status code
+ */
 efi_status_t efi_random_get_seed(void)
 {
 	efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID;
--
2.25.0