From: "Daniel P. Smith" <[email protected]>
For better or worse, Secure Launch needs SHA-1 and SHA-256. The
choice of hashes used lie with the platform firmware, not with
software, and is often outside of the users control.
Even if we'd prefer to use SHA-256-only, if firmware elected to start us
with the SHA-1 and SHA-256 backs active, we still need SHA-1 to parse
the TPM event log thus far, and deliberately cap the SHA-1 PCRs in order
to safely use SHA-256 for everything else.
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 <[email protected]>
Signed-off-by: Ross Philipson <[email protected]>
---
arch/x86/boot/compressed/Makefile | 2 +
arch/x86/boot/compressed/early_sha1.c | 12 ++++
include/crypto/sha1.h | 1 +
lib/crypto/sha1.c | 81 +++++++++++++++++++++++++++
4 files changed, 96 insertions(+)
create mode 100644 arch/x86/boot/compressed/early_sha1.c
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index e9522c6893be..3307ebef4e1b 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -118,6 +118,8 @@ vmlinux-objs-$(CONFIG_EFI) += $(obj)/efi.o
vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_mixed.o
vmlinux-objs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
+vmlinux-objs-$(CONFIG_SECURE_LAUNCH) += $(obj)/early_sha1.o
+
$(obj)/vmlinux: $(vmlinux-objs-y) FORCE
$(call if_changed,ld)
diff --git a/arch/x86/boot/compressed/early_sha1.c b/arch/x86/boot/compressed/early_sha1.c
new file mode 100644
index 000000000000..8a9b904a73ab
--- /dev/null
+++ b/arch/x86/boot/compressed/early_sha1.c
@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2024 Apertus Solutions, LLC.
+ */
+
+#include <linux/init.h>
+#include <linux/linkage.h>
+#include <linux/string.h>
+#include <asm/boot.h>
+#include <asm/unaligned.h>
+
+#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 1aebe7be9401..10152125b338 100644
--- a/lib/crypto/sha1.c
+++ b/lib/crypto/sha1.c
@@ -137,4 +137,85 @@ 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);
+
+ 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;
+
+ sctx->count += len;
+
+ if (likely((partial + len) >= SHA1_BLOCK_SIZE)) {
+ int blocks;
+
+ 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;
+ }
+
+ if (len)
+ 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);
+ sctx.count = 0;
+ sha1_update(&sctx, data, len);
+ sha1_final(&sctx, out);
+}
+EXPORT_SYMBOL(sha1);
+
MODULE_LICENSE("GPL");
--
2.39.3
On Thu, May 30, 2024 at 06:03:18PM -0700, Ross Philipson wrote:
> From: "Daniel P. Smith" <[email protected]>
>
> For better or worse, Secure Launch needs SHA-1 and SHA-256. The
> choice of hashes used lie with the platform firmware, not with
> software, and is often outside of the users control.
>
> Even if we'd prefer to use SHA-256-only, if firmware elected to start us
> with the SHA-1 and SHA-256 backs active, we still need SHA-1 to parse
> the TPM event log thus far, and deliberately cap the SHA-1 PCRs in order
> to safely use SHA-256 for everything else.
>
> 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 <[email protected]>
> Signed-off-by: Ross Philipson <[email protected]>
Thanks. This explanation doesn't seem to have made it into the actual code or
documentation. Can you please get it into a more permanent location?
Also, can you point to where the "deliberately cap the SHA-1 PCRs" thing happens
in the code?
That paragraph is also phrased as a hypothetical, "Even if we'd prefer to use
SHA-256-only". That implies that you do not, in fact, prefer SHA-256 only. Is
that the case? Sure, maybe there are situations where you *have* to use SHA-1,
but why would you not at least *prefer* SHA-256?
> /*
> * An implementation of SHA-1's compression function. Don't use in new code!
> * You shouldn't be using SHA-1, and even if you *have* to use SHA-1, this isn't
> * the correct way to hash something with SHA-1 (use crypto_shash instead).
> */
> #define SHA1_DIGEST_WORDS (SHA1_DIGEST_SIZE / 4)
> #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);
Also, the comment above needs to be updated.
- Eric
On 5/30/24 7:16 PM, Eric Biggers wrote:
> On Thu, May 30, 2024 at 06:03:18PM -0700, Ross Philipson wrote:
>> From: "Daniel P. Smith" <[email protected]>
>>
>> For better or worse, Secure Launch needs SHA-1 and SHA-256. The
>> choice of hashes used lie with the platform firmware, not with
>> software, and is often outside of the users control.
>>
>> Even if we'd prefer to use SHA-256-only, if firmware elected to start us
>> with the SHA-1 and SHA-256 backs active, we still need SHA-1 to parse
>> the TPM event log thus far, and deliberately cap the SHA-1 PCRs in order
>> to safely use SHA-256 for everything else.
>>
>> 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 <[email protected]>
>> Signed-off-by: Ross Philipson <[email protected]>
>
> Thanks. This explanation doesn't seem to have made it into the actual code or
> documentation. Can you please get it into a more permanent location?
>
> Also, can you point to where the "deliberately cap the SHA-1 PCRs" thing happens
> in the code?
>
> That paragraph is also phrased as a hypothetical, "Even if we'd prefer to use
> SHA-256-only". That implies that you do not, in fact, prefer SHA-256 only. Is
> that the case? Sure, maybe there are situations where you *have* to use SHA-1,
> but why would you not at least *prefer* SHA-256?
Yes those are fair points. We will address them and indicate we prefer
SHA-256 or better.
>
>> /*
>> * An implementation of SHA-1's compression function. Don't use in new code!
>> * You shouldn't be using SHA-1, and even if you *have* to use SHA-1, this isn't
>> * the correct way to hash something with SHA-1 (use crypto_shash instead).
>> */
>> #define SHA1_DIGEST_WORDS (SHA1_DIGEST_SIZE / 4)
>> #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);
> > Also, the comment above needs to be updated.
Ack, will address.
Thank you
>
> - Eric
On Wed Jun 5, 2024 at 12:02 AM EEST, wrote:
> On 6/4/24 11:52 AM, Jarkko Sakkinen wrote:
> > On Fri May 31, 2024 at 4:03 AM EEST, Ross Philipson wrote:
> >> From: "Daniel P. Smith" <[email protected]>
> >>
> >> For better or worse, Secure Launch needs SHA-1 and SHA-256. The
> >> choice of hashes used lie with the platform firmware, not with
> >> software, and is often outside of the users control.
> >>
> >> Even if we'd prefer to use SHA-256-only, if firmware elected to start us
> >> with the SHA-1 and SHA-256 backs active, we still need SHA-1 to parse
> >> the TPM event log thus far, and deliberately cap the SHA-1 PCRs in order
> >> to safely use SHA-256 for everything else.
> >>
> >> 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 <[email protected]>
> >> Signed-off-by: Ross Philipson <[email protected]>
> >> ---
> >> arch/x86/boot/compressed/Makefile | 2 +
> >> arch/x86/boot/compressed/early_sha1.c | 12 ++++
> >> include/crypto/sha1.h | 1 +
> >> lib/crypto/sha1.c | 81 +++++++++++++++++++++++++++
> >> 4 files changed, 96 insertions(+)
> >> create mode 100644 arch/x86/boot/compressed/early_sha1.c
> >>
> >> diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
> >> index e9522c6893be..3307ebef4e1b 100644
> >> --- a/arch/x86/boot/compressed/Makefile
> >> +++ b/arch/x86/boot/compressed/Makefile
> >> @@ -118,6 +118,8 @@ vmlinux-objs-$(CONFIG_EFI) += $(obj)/efi.o
> >> vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_mixed.o
> >> vmlinux-objs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
> >>
> >> +vmlinux-objs-$(CONFIG_SECURE_LAUNCH) += $(obj)/early_sha1.o
> >> +
> >> $(obj)/vmlinux: $(vmlinux-objs-y) FORCE
> >> $(call if_changed,ld)
> >>
> >> diff --git a/arch/x86/boot/compressed/early_sha1.c b/arch/x86/boot/compressed/early_sha1.c
> >> new file mode 100644
> >> index 000000000000..8a9b904a73ab
> >> --- /dev/null
> >> +++ b/arch/x86/boot/compressed/early_sha1.c
> >> @@ -0,0 +1,12 @@
> >> +// SPDX-License-Identifier: GPL-2.0
> >> +/*
> >> + * Copyright (c) 2024 Apertus Solutions, LLC.
> >> + */
> >> +
> >> +#include <linux/init.h>
> >> +#include <linux/linkage.h>
> >> +#include <linux/string.h>
> >> +#include <asm/boot.h>
> >> +#include <asm/unaligned.h>
> >> +
> >> +#include "../../../../lib/crypto/sha1.c"
> > }
> >
> > Yep, make sense. Thinking only that should this be just sha1.c.
> >
> > Comparing this to mainly drivers/firmware/efi/tpm.c, which is not
> > early_tpm.c where the early actually probably would make more sense
> > than here. Here sha1 primitive is just needed.
> >
> > This is definitely a nitpick but why carry a prefix that is not
> > that useful, right?
>
> I am not 100% sure what you mean here, sorry. Could you clarify about
> the prefix? Do you mean why did we choose early_*? There was precedent
> for doing that like early_serial_console.c.
Yep, that exactly. I'd just name as 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 1aebe7be9401..10152125b338 100644
> >> --- a/lib/crypto/sha1.c
> >> +++ b/lib/crypto/sha1.c
> >> @@ -137,4 +137,85 @@ 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);
> >> +
> >> + memzero_explicit(ws, sizeof(ws));
> >
> > For the sake of future reference I'd carry always some inline comment
> > with any memzero_explicit() call site.
>
> We can do that.
>
> >
> >> +}
> >> +
> >> +static void sha1_update(struct sha1_state *sctx, const u8 *data, unsigned int len)
> >> +{
> >> + unsigned int partial = sctx->count % SHA1_BLOCK_SIZE;
> >> +
> >> + sctx->count += len;
> >> +
> >> + if (likely((partial + len) >= SHA1_BLOCK_SIZE)) {
> >
> >
> > if (unlikely((partial + len) < SHA1_BLOCK_SIZE))
> > goto out;
> >
> > ?
>
> We could do it that way. I guess it would cut down in indenting. I defer
> to Daniel Smith on this...
Yep, that's why I requested this.
>
> >
> >> + int blocks;
> >> +
> >> + 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:
> >
> >> + if (len)
> >> + memcpy(sctx->buffer + partial, data, len);
> >
> > Why not just memcpy() unconditionally?
> >
>
> ... and this.
It only adds complexity with no gain.
>
> >> +}
> >> +
> >> +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);
> >> + sctx.count = 0;
> >
> > Hmm... so shouldn't C99 take care of this given the initialization
> > above? I'm not 100% sure here. I.e. given "= {0}", shouldn't this
> > already be zero?
>
> Yes it seems so. We will look at changing that.
Yeah, AFAIK C99 should zero out anything remaining.
>
> >
> >> + sha1_update(&sctx, data, len);
> >> + sha1_final(&sctx, out);
> >> +}
> >> +EXPORT_SYMBOL(sha1);
> >> +
> >> MODULE_LICENSE("GPL");
> >
> > BR, Jarkko
>
> Thanks
> Ross
BR, Jarkko