[PATCH v14 05/19] x86: Add early SHA-1 support for Secure Launch early measurements

Ross Philipson
2025-04-21T16:35:02Z

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 c4d5b9ffa31f ("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 fdbce022db55..e74228f7a607 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -107,6 +107,8 @@ vmlinux-objs-$(CONFIG_UNACCEPTED_MEMORY) += $(obj)/mem.o
vmlinux-objs-$(CONFIG_EFI) += $(obj)/efi.o
vmlinux-libs-$(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..f58ab7cadb46
--- /dev/null
+++ b/arch/x86/boot/compressed/sha1.c
@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2025 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