Changes in libcrypto-auth-encryption.rst

d47db9bf50d28647689e6743ee93c45cb755ffc3 - Merge tag 'libcrypto-updates-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux

Tue, 18 Aug 2026 04:16:42 +0200

Merge tag 'libcrypto-updates-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linuxPull crypto library updates from Eric Biggers: "Add library APIs for most AES encryption modes that are used in the kernel (ECB, CBC, CBC-CTS, CTR, XCTR, XTS, GCM, CCM). These AES modes have many in-kernel users that are currently using the crypto_skcipher or crypto_aead APIs. These existing APIs are difficult to use and inefficient. Until now, the lack of proper library support for these has been the main gap in the crypto library. This set of changes is the next stage of addressing it: - Implement the new APIs on top of the existing support for single-block AES in the library. - Fully document the new APIs. - Migrate the only user of the old AES-GCM library API to the new, more flexible API; then remove the old API and its implementation. - Wire up the new APIs to the traditional crypto API by adding crypto_skcipher and crypto_aead algorithms. This makes the new APIs be covered by the traditional crypto API's self-tests. It also makes them be already used for real on systems that don't have architecture-optimized code for these modes. But most importantly, this is a prerequisite for migrating the architecture-optimized code for these AES modes (i.e. arch/*/crypto/aes*) into the library, which as usual will eliminate a lot of redundant "glue" code. Note that unlike some of the other algorithms that have been migrated to the library, e.g. SHA-512, for these AES modes there was too much to get done in one cycle. Nor did it make sense to handle these modes one at a time, because they tend to be coupled together or depend on each other, especially in the architecture-optimized AES code. Thus, most of the benefits (reductions in lines of code, performance improvements, etc.) will follow in later cycles when architecture-optimized code is migrated into the library and users of crypto_skcipher and crypto_aead are updated to use the new APIs. The design of the new APIs was informed by writing proof-of-concept patches for many kernel subsystems currently accessing these same algorithms via crypto_skcipher or crypto_aead (patches 18-33 of https://lore.kernel.org/r/20260707053503.209874-1-ebiggers@kernel.org/). While those patches will be resent for real later, the total diffstat for them was negative 1905 lines. So clearly the new APIs are quite a bit easier to use and align better with what users actually need. Besides the new AES encryption APIs, there are also a few changes for improved AES-CMAC key and context zeroization"* tag 'libcrypto-updates-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux: mac80211: fils_aead: Use __cleanup() instead of memzero_explicit() Bluetooth: SMP: clear the aes_cmac_key when done smb: clear the aes_cmac_key and aes_cmac_ctx when done lib/crypto: aes-cmac: Add zeroization functions lib/crypto: aesgcm: Remove old AES-GCM library x86/sev: Remove obsolete virtual address check x86/sev: Use new AES-GCM library crypto: aes - Add CCM support using library crypto: aes - Add GCM support using library crypto: aes - Add XTS support using library crypto: aes - Add CTR and XCTR support using library crypto: aes - Add CBC and CBC-CTS support using library crypto: aes - Add ECB support using library lib/crypto: aes: Add CCM support lib/crypto: aes: Add GCM support lib/crypto: aes: Add XTS support lib/crypto: aes: Add CTR and XCTR support lib/crypto: aes: Add CBC and CBC-CTS support lib/crypto: aes: Add ECB support crypto: xts - Split out __xts_verify_key() helper List of files: /linux/Documentation/crypto/libcrypto-auth-encryption.rst

6a1f9969cb79e0e194c160e0737ab301d7da21c1 - lib/crypto: aes: Add CCM support

Thu, 16 Jul 2026 00:11:47 +0200

lib/crypto: aes: Add CCM supportAdd 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 beable to switch to the library, which as usual will be faster andsimpler, e.g.: - fs/smb/client/ - fs/smb/server/ - net/mac80211/ - net/mac802154/(I've already written proof-of-concept patches for all the above, andthey helped inform the API design.)As in the AES-GCM API, incremental operation is supported. It has to beused carefully, especially when decrypting, but it makes the API generalenough to work well for all users.The AES-CCM library code calls aes_cbcmac_blocks() directly, bypassingthe higher-level aes_cbcmac_init(), aes_cbcmac_update(), andaes_cbcmac_final(). The latter set of functions is useful only forAES-CCM, so they don't make sense to keep around and will be removedonce the "ccm(aes)" crypto_aead starts using the AES-CCM library.Initial test coverage is provided by the crypto_aead support added in alater commit. I'm planning a KUnit test suite as well.Link: https://patch.msgid.link/20260715221153.246410-8-ebiggers@kernel.orgSigned-off-by: Eric Biggers List of files: /linux/Documentation/crypto/libcrypto-auth-encryption.rst

2a87486bc5c2bcb6c8085c4e4a3c8ee73a7c5c75 - lib/crypto: aes: Add GCM support

Thu, 16 Jul 2026 00:11:46 +0200

lib/crypto: aes: Add GCM supportAdd 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 usersof these will also be able to switch to the library, which as usual willbe 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, andthey helped inform the API design.)As usual, the architecture-optimized AES-GCM code will be migrated intothe library as well (using the hooks provided in this commit as well asthe GHASH ones), eliminating lots of repetitive boilerplate code.Incremental en/decryption is supported. Incremental operation is a bitcontroversial in AEAD APIs because users have to be careful not toconsume any decrypted data that hasn't been authenticated yet. But I dothink it's the right choice here. It's not fundamentally different fromthe existing incremental MAC APIs, and it's the only approach that'sgeneral 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 alater commit. I'm planning a KUnit test suite as well.Link: https://patch.msgid.link/20260715221153.246410-7-ebiggers@kernel.orgLink: https://patch.msgid.link/20260722021730.16897-1-ebiggers@kernel.orgSigned-off-by: Eric Biggers List of files: /linux/Documentation/crypto/libcrypto-auth-encryption.rst