2019-07-02 21:41:22 +02:00
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lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2019-07-02 21:41:22 +02:00
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lib/crypto: aes: Add support for CBC-based MACs
Add support for CBC-based MACs to the AES library, specifically
AES-CMAC, AES-XCBC-MAC, and AES-CBC-MAC.
Of these three algorithms, AES-CMAC is the most modern and the most
commonly used. Use cases for the AES-CMAC library include the kernel's
SMB client and server, and the bluetooth and mac80211 drivers.
Support for AES-XCBC-MAC and AES-CBC-MAC is included so that there will
be no performance regression in the "xcbc(aes)" and "ccm(aes)" support
in the traditional crypto API once the arm64-optimized code is migrated
into the library. AES-XCBC-MAC is given its own key preparation
function but is otherwise identical to AES-CMAC and just reuses the
AES-CMAC structs and functions.
The implementation automatically uses the optimized AES key expansion
and single block en/decryption functions. It also allows architectures
to provide an optimized implementation of aes_cbcmac_blocks(), which
allows the existing arm64-optimized code for these modes to be used.
Just put the code for these modes directly in the libaes module rather
than in a separate module. This is simpler, it makes it easier to share
code between AES modes, and it increases the amount of inlining that is
possible. (Indeed, for these reasons, most of the
architecture-optimized AES code already provides multiple modes per
module. x86 for example has only a single aesni-intel module. So to a
large extent, this design choice just reflects the status quo.)
However, since there are a lot of AES modes, there's still some value in
omitting modes that are not needed at all in a given kernel. Therefore,
make these modes an optional feature of libaes, controlled by
CONFIG_CRYPTO_LIB_AES_CBC_MACS. This seems like a good middle ground.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260218213501.136844-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-02-18 13:34:47 -08:00
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2026-07-15 15:11:43 -07:00
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lib/crypto: aes: Add CCM support
Add support for AES-CCM to the crypto library.
This will be used to provide a streamlined implementation of the
"ccm(aes)" crypto_aead algorithm. Most users of "ccm(aes)" will also be
able to switch to the library, which as usual will be faster and
simpler, e.g.:
- fs/smb/client/
- fs/smb/server/
- net/mac80211/
- net/mac802154/
(I've already written proof-of-concept patches for all the above, and
they helped inform the API design.)
As in the AES-GCM API, incremental operation is supported. It has to be
used carefully, especially when decrypting, but it makes the API general
enough to work well for all users.
The AES-CCM library code calls aes_cbcmac_blocks() directly, bypassing
the higher-level aes_cbcmac_init(), aes_cbcmac_update(), and
aes_cbcmac_final(). The latter set of functions is useful only for
AES-CCM, so they don't make sense to keep around and will be removed
once the "ccm(aes)" crypto_aead starts using the AES-CCM library.
Initial test coverage is provided by the crypto_aead support added in a
later commit. I'm planning a KUnit test suite as well.
Link: https://patch.msgid.link/20260715221153.246410-8-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-07-15 15:11:47 -07:00
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2026-07-15 15:11:44 -07:00
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2026-07-15 15:11:42 -07:00
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lib/crypto: aes: Add GCM support
Add support for AES-GCM to the crypto library.
This will be used to provide streamlined implementations of the
"gcm(aes)" and "rfc4106(gcm(aes))" crypto_aead algorithms. Most users
of these will also be able to switch to the library, which as usual will
be faster and simpler, e.g.:
- drivers/net/macsec.c
- fs/smb/client/
- fs/smb/server/
- net/ceph/messenger_v2.c
- net/mac80211/ (for both GMAC and GCMP)
- net/tipc/crypto.c
- security/keys/trusted-keys/trusted_dcp.c
(I've already written proof-of-concept patches for all the above, and
they helped inform the API design.)
As usual, the architecture-optimized AES-GCM code will be migrated into
the library as well (using the hooks provided in this commit as well as
the GHASH ones), eliminating lots of repetitive boilerplate code.
Incremental en/decryption is supported. Incremental operation is a bit
controversial in AEAD APIs because users have to be careful not to
consume any decrypted data that hasn't been authenticated yet. But I do
think it's the right choice here. It's not fundamentally different from
the existing incremental MAC APIs, and it's the only approach that's
general enough to work well for all users in the kernel:
- An array of virtually-addressed buffers (like that used by
BoringSSL's EVP_AEAD_CTX_sealv() and EVP_AEAD_CTX_openv()) doesn't
work in the kernel in general, since in some cases the data for a
single AES-GCM message is contained in a large number of highmem
pages that each need to be mapped into memory individually. That
can be done efficiently only by using CPU-local mappings, but there
is a limited number of those.
Ceph messenger v2 is a great example, as it can send or receive up
to 32 MiB in a single AES-GCM message. And it needs the
en/decrypted data to go into a (potentially large) number of bvecs
provided by a custom iterator, as well as into four
virtually-addressed buffers, two of which can be large buffers in
the vmalloc region.
Even just allocating an array big enough to store all the pointers
can be problematic in the kernel. There are cases in which
decryption runs in GFP_NOIO context or even in softirq context,
where memory allocations are not as reliable as they normally are.
- Meanwhile, 'struct scatterlist' (the choice of crypto_aead) has
turned out to be really inconvenient for anyone who *does* just have
virtually-addressed buffers. This is especially true if they can be
in the vmalloc region, including the stack, as in that case the
conversion to a scatterlist has to be done page-by-page.
And even for users who have all of their data in bare 'struct page',
none of them actually use 'struct scatterlist' as their native data
structure anyway. They actually use skbs, bvecs, or other formats.
- iov_iter is attractive, but ultimately not general enough either
(considering the Ceph case for example), but also too general in
some ways (like having support for userspace addresses). Additional
iter types like ITER_SKB would help a bit, but bloating iov_iter
with more types would reduce performance elsewhere in the kernel.
Initial test coverage is provided by the crypto_aead support added in a
later commit. I'm planning a KUnit test suite as well.
Link: https://patch.msgid.link/20260715221153.246410-7-ebiggers@kernel.org
Link: https://patch.msgid.link/20260722021730.16897-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-07-15 15:11:46 -07:00
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2026-07-15 15:11:45 -07:00
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2019-07-02 21:41:22 +02:00
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2026-07-15 15:11:45 -07:00
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lib/crypto: aes: Add support for CBC-based MACs
Add support for CBC-based MACs to the AES library, specifically
AES-CMAC, AES-XCBC-MAC, and AES-CBC-MAC.
Of these three algorithms, AES-CMAC is the most modern and the most
commonly used. Use cases for the AES-CMAC library include the kernel's
SMB client and server, and the bluetooth and mac80211 drivers.
Support for AES-XCBC-MAC and AES-CBC-MAC is included so that there will
be no performance regression in the "xcbc(aes)" and "ccm(aes)" support
in the traditional crypto API once the arm64-optimized code is migrated
into the library. AES-XCBC-MAC is given its own key preparation
function but is otherwise identical to AES-CMAC and just reuses the
AES-CMAC structs and functions.
The implementation automatically uses the optimized AES key expansion
and single block en/decryption functions. It also allows architectures
to provide an optimized implementation of aes_cbcmac_blocks(), which
allows the existing arm64-optimized code for these modes to be used.
Just put the code for these modes directly in the libaes module rather
than in a separate module. This is simpler, it makes it easier to share
code between AES modes, and it increases the amount of inlining that is
possible. (Indeed, for these reasons, most of the
architecture-optimized AES code already provides multiple modes per
module. x86 for example has only a single aesni-intel module. So to a
large extent, this design choice just reflects the status quo.)
However, since there are a lot of AES modes, there's still some value in
omitting modes that are not needed at all in a given kernel. Therefore,
make these modes an optional feature of libaes, controlled by
CONFIG_CRYPTO_LIB_AES_CBC_MACS. This seems like a good middle ground.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260218213501.136844-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-02-18 13:34:47 -08:00
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lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2019-07-02 21:41:22 +02:00
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2025-06-13 11:48:14 -07:00
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2019-07-02 21:41:22 +02:00
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2024-10-01 15:35:57 -04:00
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2026-08-02 15:24:06 -07:00
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2019-07-02 21:41:22 +02:00
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2026-01-12 11:20:33 -08:00
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2019-07-02 21:41:22 +02:00
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2026-01-12 11:20:33 -08:00
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2019-07-02 21:41:22 +02:00
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2019-07-02 21:41:46 +02:00
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lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2019-07-02 21:41:22 +02:00
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lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2019-07-02 21:41:22 +02:00
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lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
|
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|
2019-07-02 21:41:22 +02:00
|
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|
|
lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2019-07-02 21:41:22 +02:00
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lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2019-07-02 21:41:22 +02:00
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|
lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2019-07-02 21:41:22 +02:00
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|
lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2019-07-02 21:41:22 +02:00
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lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2019-07-02 21:41:22 +02:00
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lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2026-01-12 11:20:33 -08:00
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lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2026-01-12 11:20:32 -08:00
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lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2026-01-12 11:20:32 -08:00
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lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2026-01-12 11:20:32 -08:00
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lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2026-01-12 11:20:32 -08:00
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lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2026-08-02 15:24:07 -07:00
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lib/crypto: aes: Add support for CBC-based MACs
Add support for CBC-based MACs to the AES library, specifically
AES-CMAC, AES-XCBC-MAC, and AES-CBC-MAC.
Of these three algorithms, AES-CMAC is the most modern and the most
commonly used. Use cases for the AES-CMAC library include the kernel's
SMB client and server, and the bluetooth and mac80211 drivers.
Support for AES-XCBC-MAC and AES-CBC-MAC is included so that there will
be no performance regression in the "xcbc(aes)" and "ccm(aes)" support
in the traditional crypto API once the arm64-optimized code is migrated
into the library. AES-XCBC-MAC is given its own key preparation
function but is otherwise identical to AES-CMAC and just reuses the
AES-CMAC structs and functions.
The implementation automatically uses the optimized AES key expansion
and single block en/decryption functions. It also allows architectures
to provide an optimized implementation of aes_cbcmac_blocks(), which
allows the existing arm64-optimized code for these modes to be used.
Just put the code for these modes directly in the libaes module rather
than in a separate module. This is simpler, it makes it easier to share
code between AES modes, and it increases the amount of inlining that is
possible. (Indeed, for these reasons, most of the
architecture-optimized AES code already provides multiple modes per
module. x86 for example has only a single aesni-intel module. So to a
large extent, this design choice just reflects the status quo.)
However, since there are a lot of AES modes, there's still some value in
omitting modes that are not needed at all in a given kernel. Therefore,
make these modes an optional feature of libaes, controlled by
CONFIG_CRYPTO_LIB_AES_CBC_MACS. This seems like a good middle ground.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260218213501.136844-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-02-18 13:34:47 -08:00
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2026-08-02 15:24:08 -07:00
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2026-02-18 13:34:53 -08:00
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2026-08-07 14:58:42 +02:00
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2026-02-18 13:34:53 -08:00
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2026-07-15 15:11:42 -07:00
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2026-08-02 15:24:07 -07:00
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2026-07-15 15:11:42 -07:00
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2026-07-15 15:11:43 -07:00
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2026-08-02 15:24:07 -07:00
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2026-07-15 15:11:43 -07:00
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2026-07-15 15:11:44 -07:00
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2026-08-02 15:24:07 -07:00
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2026-07-15 15:11:44 -07:00
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2026-07-15 15:11:45 -07:00
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2026-08-02 15:24:07 -07:00
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2026-07-15 15:11:45 -07:00
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lib/crypto: aes: Add GCM support
Add support for AES-GCM to the crypto library.
This will be used to provide streamlined implementations of the
"gcm(aes)" and "rfc4106(gcm(aes))" crypto_aead algorithms. Most users
of these will also be able to switch to the library, which as usual will
be faster and simpler, e.g.:
- drivers/net/macsec.c
- fs/smb/client/
- fs/smb/server/
- net/ceph/messenger_v2.c
- net/mac80211/ (for both GMAC and GCMP)
- net/tipc/crypto.c
- security/keys/trusted-keys/trusted_dcp.c
(I've already written proof-of-concept patches for all the above, and
they helped inform the API design.)
As usual, the architecture-optimized AES-GCM code will be migrated into
the library as well (using the hooks provided in this commit as well as
the GHASH ones), eliminating lots of repetitive boilerplate code.
Incremental en/decryption is supported. Incremental operation is a bit
controversial in AEAD APIs because users have to be careful not to
consume any decrypted data that hasn't been authenticated yet. But I do
think it's the right choice here. It's not fundamentally different from
the existing incremental MAC APIs, and it's the only approach that's
general enough to work well for all users in the kernel:
- An array of virtually-addressed buffers (like that used by
BoringSSL's EVP_AEAD_CTX_sealv() and EVP_AEAD_CTX_openv()) doesn't
work in the kernel in general, since in some cases the data for a
single AES-GCM message is contained in a large number of highmem
pages that each need to be mapped into memory individually. That
can be done efficiently only by using CPU-local mappings, but there
is a limited number of those.
Ceph messenger v2 is a great example, as it can send or receive up
to 32 MiB in a single AES-GCM message. And it needs the
en/decrypted data to go into a (potentially large) number of bvecs
provided by a custom iterator, as well as into four
virtually-addressed buffers, two of which can be large buffers in
the vmalloc region.
Even just allocating an array big enough to store all the pointers
can be problematic in the kernel. There are cases in which
decryption runs in GFP_NOIO context or even in softirq context,
where memory allocations are not as reliable as they normally are.
- Meanwhile, 'struct scatterlist' (the choice of crypto_aead) has
turned out to be really inconvenient for anyone who *does* just have
virtually-addressed buffers. This is especially true if they can be
in the vmalloc region, including the stack, as in that case the
conversion to a scatterlist has to be done page-by-page.
And even for users who have all of their data in bare 'struct page',
none of them actually use 'struct scatterlist' as their native data
structure anyway. They actually use skbs, bvecs, or other formats.
- iov_iter is attractive, but ultimately not general enough either
(considering the Ceph case for example), but also too general in
some ways (like having support for userspace addresses). Additional
iter types like ITER_SKB would help a bit, but bloating iov_iter
with more types would reduce performance elsewhere in the kernel.
Initial test coverage is provided by the crypto_aead support added in a
later commit. I'm planning a KUnit test suite as well.
Link: https://patch.msgid.link/20260715221153.246410-7-ebiggers@kernel.org
Link: https://patch.msgid.link/20260722021730.16897-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-07-15 15:11:46 -07:00
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2026-08-02 15:24:08 -07:00
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lib/crypto: aes: Add GCM support
Add support for AES-GCM to the crypto library.
This will be used to provide streamlined implementations of the
"gcm(aes)" and "rfc4106(gcm(aes))" crypto_aead algorithms. Most users
of these will also be able to switch to the library, which as usual will
be faster and simpler, e.g.:
- drivers/net/macsec.c
- fs/smb/client/
- fs/smb/server/
- net/ceph/messenger_v2.c
- net/mac80211/ (for both GMAC and GCMP)
- net/tipc/crypto.c
- security/keys/trusted-keys/trusted_dcp.c
(I've already written proof-of-concept patches for all the above, and
they helped inform the API design.)
As usual, the architecture-optimized AES-GCM code will be migrated into
the library as well (using the hooks provided in this commit as well as
the GHASH ones), eliminating lots of repetitive boilerplate code.
Incremental en/decryption is supported. Incremental operation is a bit
controversial in AEAD APIs because users have to be careful not to
consume any decrypted data that hasn't been authenticated yet. But I do
think it's the right choice here. It's not fundamentally different from
the existing incremental MAC APIs, and it's the only approach that's
general enough to work well for all users in the kernel:
- An array of virtually-addressed buffers (like that used by
BoringSSL's EVP_AEAD_CTX_sealv() and EVP_AEAD_CTX_openv()) doesn't
work in the kernel in general, since in some cases the data for a
single AES-GCM message is contained in a large number of highmem
pages that each need to be mapped into memory individually. That
can be done efficiently only by using CPU-local mappings, but there
is a limited number of those.
Ceph messenger v2 is a great example, as it can send or receive up
to 32 MiB in a single AES-GCM message. And it needs the
en/decrypted data to go into a (potentially large) number of bvecs
provided by a custom iterator, as well as into four
virtually-addressed buffers, two of which can be large buffers in
the vmalloc region.
Even just allocating an array big enough to store all the pointers
can be problematic in the kernel. There are cases in which
decryption runs in GFP_NOIO context or even in softirq context,
where memory allocations are not as reliable as they normally are.
- Meanwhile, 'struct scatterlist' (the choice of crypto_aead) has
turned out to be really inconvenient for anyone who *does* just have
virtually-addressed buffers. This is especially true if they can be
in the vmalloc region, including the stack, as in that case the
conversion to a scatterlist has to be done page-by-page.
And even for users who have all of their data in bare 'struct page',
none of them actually use 'struct scatterlist' as their native data
structure anyway. They actually use skbs, bvecs, or other formats.
- iov_iter is attractive, but ultimately not general enough either
(considering the Ceph case for example), but also too general in
some ways (like having support for userspace addresses). Additional
iter types like ITER_SKB would help a bit, but bloating iov_iter
with more types would reduce performance elsewhere in the kernel.
Initial test coverage is provided by the crypto_aead support added in a
later commit. I'm planning a KUnit test suite as well.
Link: https://patch.msgid.link/20260715221153.246410-7-ebiggers@kernel.org
Link: https://patch.msgid.link/20260722021730.16897-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-07-15 15:11:46 -07:00
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|
lib/crypto: aes: Add CCM support
Add support for AES-CCM to the crypto library.
This will be used to provide a streamlined implementation of the
"ccm(aes)" crypto_aead algorithm. Most users of "ccm(aes)" will also be
able to switch to the library, which as usual will be faster and
simpler, e.g.:
- fs/smb/client/
- fs/smb/server/
- net/mac80211/
- net/mac802154/
(I've already written proof-of-concept patches for all the above, and
they helped inform the API design.)
As in the AES-GCM API, incremental operation is supported. It has to be
used carefully, especially when decrypting, but it makes the API general
enough to work well for all users.
The AES-CCM library code calls aes_cbcmac_blocks() directly, bypassing
the higher-level aes_cbcmac_init(), aes_cbcmac_update(), and
aes_cbcmac_final(). The latter set of functions is useful only for
AES-CCM, so they don't make sense to keep around and will be removed
once the "ccm(aes)" crypto_aead starts using the AES-CCM library.
Initial test coverage is provided by the crypto_aead support added in a
later commit. I'm planning a KUnit test suite as well.
Link: https://patch.msgid.link/20260715221153.246410-8-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-07-15 15:11:47 -07:00
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2026-08-02 15:24:08 -07:00
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lib/crypto: aes: Add CCM support
Add support for AES-CCM to the crypto library.
This will be used to provide a streamlined implementation of the
"ccm(aes)" crypto_aead algorithm. Most users of "ccm(aes)" will also be
able to switch to the library, which as usual will be faster and
simpler, e.g.:
- fs/smb/client/
- fs/smb/server/
- net/mac80211/
- net/mac802154/
(I've already written proof-of-concept patches for all the above, and
they helped inform the API design.)
As in the AES-GCM API, incremental operation is supported. It has to be
used carefully, especially when decrypting, but it makes the API general
enough to work well for all users.
The AES-CCM library code calls aes_cbcmac_blocks() directly, bypassing
the higher-level aes_cbcmac_init(), aes_cbcmac_update(), and
aes_cbcmac_final(). The latter set of functions is useful only for
AES-CCM, so they don't make sense to keep around and will be removed
once the "ccm(aes)" crypto_aead starts using the AES-CCM library.
Initial test coverage is provided by the crypto_aead support added in a
later commit. I'm planning a KUnit test suite as well.
Link: https://patch.msgid.link/20260715221153.246410-8-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-07-15 15:11:47 -07:00
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lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2026-02-18 13:34:53 -08:00
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lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2026-02-18 13:34:53 -08:00
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2026-08-02 15:24:07 -07:00
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2026-02-18 13:34:53 -08:00
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2026-08-02 15:24:07 -07:00
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2026-08-02 15:24:08 -07:00
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2026-08-02 15:24:07 -07:00
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lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2019-07-02 21:41:22 +02:00
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lib/crypto: aes: Introduce improved AES library
The kernel's AES library currently has the following issues:
- It doesn't take advantage of the architecture-optimized AES code,
including the implementations using AES instructions.
- It's much slower than even the other software AES implementations: 2-4
times slower than "aes-generic", "aes-arm", and "aes-arm64".
- It requires that both the encryption and decryption round keys be
computed and cached. This is wasteful for users that need only the
forward (encryption) direction of the cipher: the key struct is 484
bytes when only 244 are actually needed. This missed optimization is
very common, as many AES modes (e.g. GCM, CFB, CTR, CMAC, and even the
tweak key in XTS) use the cipher only in the forward (encryption)
direction even when doing decryption.
- It doesn't provide the flexibility to customize the prepared key
format. The API is defined to do key expansion, and several callers
in drivers/crypto/ use it specifically to expand the key. This is an
issue when integrating the existing powerpc, s390, and sparc code,
which is necessary to provide full parity with the traditional API.
To resolve these issues, I'm proposing the following changes:
1. New structs 'aes_key' and 'aes_enckey' are introduced, with
corresponding functions aes_preparekey() and aes_prepareenckey().
Generally these structs will include the encryption+decryption round
keys and the encryption round keys, respectively. However, the exact
format will be under control of the architecture-specific AES code.
(The verb "prepare" is chosen over "expand" since key expansion isn't
necessarily done. It's also consistent with hmac*_preparekey().)
2. aes_encrypt() and aes_decrypt() will be changed to operate on the new
structs instead of struct crypto_aes_ctx.
3. aes_encrypt() and aes_decrypt() will use architecture-optimized code
when available, or else fall back to a new generic AES implementation
that unifies the existing two fragmented generic AES implementations.
The new generic AES implementation uses tables for both SubBytes and
MixColumns, making it almost as fast as "aes-generic". However,
instead of aes-generic's huge 8192-byte tables per direction, it uses
only 1024 bytes for encryption and 1280 bytes for decryption (similar
to "aes-arm"). The cost is just some extra rotations.
The new generic AES implementation also includes table prefetching,
making it have some "constant-time hardening". That's an improvement
from aes-generic which has no constant-time hardening.
It does slightly regress in constant-time hardening vs. the old
lib/crypto/aes.c which had smaller tables, and from aes-fixed-time
which disabled IRQs on top of that. But I think this is tolerable.
The real solutions for constant-time AES are AES instructions or
bit-slicing. The table-based code remains a best-effort fallback for
the increasingly-rare case where a real solution is unavailable.
4. crypto_aes_ctx and aes_expandkey() will remain for now, but only for
callers that are using them specifically for the AES key expansion
(as opposed to en/decrypting data with the AES library).
This commit begins the migration process by introducing the new structs
and functions, backed by the new generic AES implementation.
To allow callers to be incrementally converted, aes_encrypt() and
aes_decrypt() are temporarily changed into macros that use a _Generic
expression to call either the old functions (which take crypto_aes_ctx)
or the new functions (which take the new types). Once all callers have
been updated, these macros will go away, the old functions will be
removed, and the "_new" suffix will be dropped from the new functions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-01-12 11:20:00 -08:00
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2019-07-02 21:41:22 +02:00
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