Re: [PATCH v12 05/19] x86: Add early SHA-1 support for Secure Launch early measurements

[Jarkko Sakkinen <jarkko@kernel.org>]

On Thu, Dec 19, 2024 at 11:42:02AM -0800, Ross Philipson wrote:
> From: "Daniel P. Smith" <dpsmith@apertussolutions.com>
> 
> Secure Launch is written to be compliant with the Intel TXT Measured Launch
> Developer's Guide. The MLE Guide dictates that the system can be configured to
> use both the SHA-1 and SHA-2 hashing algorithms.
> 
> Regardless of the preference towards SHA-2, if the firmware elected to start
> with the SHA-1 and SHA-2 banks active and the dynamic launch was configured to
> include SHA-1, Secure Launch is obligated to record measurements for all
> algorithms requested in the launch configuration.
> 
> The user environment or the integrity management does not desire to use SHA-1,
> it is free to just ignore the SHA-1 bank in any integrity operation with the
> TPM. If there is a larger concern about the SHA-1 bank being active, it is free
> to deliberately cap the SHA-1 PCRs, recording the event in the D-RTM log.
> 
> The SHA-1 code here has its origins in the code from the main kernel:
> 
> commit c4d5b9f ("crypto: sha1 - implement base layer for SHA-1")
> 
> A modified version of this code was introduced to the lib/crypto/sha1.c to bring
> it in line with the SHA-256 code and allow it to be pulled into the setup kernel
> in the same manner as SHA-256 is.
> 
> Signed-off-by: Daniel P. Smith <dpsmith@apertussolutions.com>
> Signed-off-by: Ross Philipson <ross.philipson@oracle.com>
> ---
>  arch/x86/boot/compressed/Makefile |  2 +
>  arch/x86/boot/compressed/sha1.c   |  6 +++
>  include/crypto/sha1.h             |  1 +
>  lib/crypto/sha1.c                 | 81 +++++++++++++++++++++++++++++++
>  4 files changed, 90 insertions(+)
>  create mode 100644 arch/x86/boot/compressed/sha1.c
> 
> diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
> index f2051644de94..7eb03afb841b 100644
> --- a/arch/x86/boot/compressed/Makefile
> +++ b/arch/x86/boot/compressed/Makefile
> @@ -107,6 +107,8 @@ vmlinux-objs-$(CONFIG_EFI) += $(obj)/efi.o
>  vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_mixed.o
>  vmlinux-libs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
>  
> +vmlinux-objs-$(CONFIG_SECURE_LAUNCH) += $(obj)/sha1.o
> +
>  $(obj)/vmlinux: $(vmlinux-objs-y) $(vmlinux-libs-y) FORCE
>  	$(call if_changed,ld)
>  
> diff --git a/arch/x86/boot/compressed/sha1.c b/arch/x86/boot/compressed/sha1.c
> new file mode 100644
> index 000000000000..d754489941ac
> --- /dev/null
> +++ b/arch/x86/boot/compressed/sha1.c
> @@ -0,0 +1,6 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2024 Apertus Solutions, LLC.
> + */
> +
> +#include "../../../../lib/crypto/sha1.c"
> diff --git a/include/crypto/sha1.h b/include/crypto/sha1.h
> index 044ecea60ac8..d715dd5332e1 100644
> --- a/include/crypto/sha1.h
> +++ b/include/crypto/sha1.h
> @@ -42,5 +42,6 @@ extern int crypto_sha1_finup(struct shash_desc *desc, const u8 *data,
>  #define SHA1_WORKSPACE_WORDS	16
>  void sha1_init(__u32 *buf);
>  void sha1_transform(__u32 *digest, const char *data, __u32 *W);
> +void sha1(const u8 *data, unsigned int len, u8 *out);
>  
>  #endif /* _CRYPTO_SHA1_H */
> diff --git a/lib/crypto/sha1.c b/lib/crypto/sha1.c
> index ebb60519ae93..0bd32df31743 100644
> --- a/lib/crypto/sha1.c
> +++ b/lib/crypto/sha1.c
> @@ -137,5 +137,86 @@ void sha1_init(__u32 *buf)
>  }
>  EXPORT_SYMBOL(sha1_init);
>  
> +static void __sha1_transform(u32 *digest, const char *data)
> +{
> +	u32 ws[SHA1_WORKSPACE_WORDS];
> +
> +	sha1_transform(digest, data, ws);
> +
> +	/* Ensure local data for generating digest is cleared in all cases */
> +	memzero_explicit(ws, sizeof(ws));
> +}
> +
> +static void sha1_update(struct sha1_state *sctx, const u8 *data, unsigned int len)
> +{
> +	unsigned int partial = sctx->count % SHA1_BLOCK_SIZE;
> +	int blocks;
> +
> +	sctx->count += len;
> +
> +	if (unlikely((partial + len) < SHA1_BLOCK_SIZE))
> +		goto out;
> +
> +	if (partial) {
> +		int p = SHA1_BLOCK_SIZE - partial;
> +
> +		memcpy(sctx->buffer + partial, data, p);
> +		data += p;
> +		len -= p;
> +
> +		__sha1_transform(sctx->state, sctx->buffer);
> +	}
> +
> +	blocks = len / SHA1_BLOCK_SIZE;
> +	len %= SHA1_BLOCK_SIZE;
> +
> +	if (blocks) {
> +		while (blocks--) {
> +			__sha1_transform(sctx->state, data);
> +			data += SHA1_BLOCK_SIZE;
> +		}
> +	}
> +	partial = 0;
> +
> +out:
> +	memcpy(sctx->buffer + partial, data, len);
> +}
> +
> +static void sha1_final(struct sha1_state *sctx, u8 *out)
> +{
> +	const int bit_offset = SHA1_BLOCK_SIZE - sizeof(__be64);
> +	unsigned int partial = sctx->count % SHA1_BLOCK_SIZE;
> +	__be64 *bits = (__be64 *)(sctx->buffer + bit_offset);
> +	__be32 *digest = (__be32 *)out;
> +	int i;
> +
> +	sctx->buffer[partial++] = 0x80;
> +	if (partial > bit_offset) {
> +		memset(sctx->buffer + partial, 0x0, SHA1_BLOCK_SIZE - partial);
> +		partial = 0;
> +
> +		__sha1_transform(sctx->state, sctx->buffer);
> +	}
> +
> +	memset(sctx->buffer + partial, 0x0, bit_offset - partial);
> +	*bits = cpu_to_be64(sctx->count << 3);
> +	__sha1_transform(sctx->state, sctx->buffer);
> +
> +	for (i = 0; i < SHA1_DIGEST_SIZE / sizeof(__be32); i++)
> +		put_unaligned_be32(sctx->state[i], digest++);
> +
> +	*sctx = (struct sha1_state){};
> +}
> +
> +void sha1(const u8 *data, unsigned int len, u8 *out)
> +{
> +	struct sha1_state sctx = {0};
> +
> +	sha1_init(sctx.state);
> +	sha1_update(&sctx, data, len);
> +	sha1_final(&sctx, out);
> +}
> +EXPORT_SYMBOL(sha1);
> +
>  MODULE_DESCRIPTION("SHA-1 Algorithm");
>  MODULE_LICENSE("GPL");
> -- 
> 2.39.3
> 

This looks pretty good and we had already the SHA-1 discussion in
the past :-)

BR, Jarkko