Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

18 files changed, 2983 insertions, 0 deletions

diff --git a/Documentation/crypto/api-aead.rst b/Documentation/crypto/api-aead.rst
new file mode 100644
index 000000000..d15256f1a
--- /dev/null
+++ b/Documentation/crypto/api-aead.rst
@@ -0,0 +1,23 @@
+Authenticated Encryption With Associated Data (AEAD) Algorithm Definitions
+--------------------------------------------------------------------------
+
+.. kernel-doc:: include/crypto/aead.h
+   :doc: Authenticated Encryption With Associated Data (AEAD) Cipher API
+
+.. kernel-doc:: include/crypto/aead.h
+   :functions: aead_request aead_alg
+
+Authenticated Encryption With Associated Data (AEAD) Cipher API
+---------------------------------------------------------------
+
+.. kernel-doc:: include/crypto/aead.h
+   :functions: crypto_alloc_aead crypto_free_aead crypto_aead_ivsize crypto_aead_authsize crypto_aead_blocksize crypto_aead_setkey crypto_aead_setauthsize crypto_aead_encrypt crypto_aead_decrypt
+
+Asynchronous AEAD Request Handle
+--------------------------------
+
+.. kernel-doc:: include/crypto/aead.h
+   :doc: Asynchronous AEAD Request Handle
+
+.. kernel-doc:: include/crypto/aead.h
+   :functions: crypto_aead_reqsize aead_request_set_tfm aead_request_alloc aead_request_free aead_request_set_callback aead_request_set_crypt aead_request_set_ad
diff --git a/Documentation/crypto/api-akcipher.rst b/Documentation/crypto/api-akcipher.rst
new file mode 100644
index 000000000..40aa8746e
--- /dev/null
+++ b/Documentation/crypto/api-akcipher.rst
@@ -0,0 +1,20 @@
+Asymmetric Cipher Algorithm Definitions
+---------------------------------------
+
+.. kernel-doc:: include/crypto/akcipher.h
+   :functions: akcipher_alg akcipher_request
+
+Asymmetric Cipher API
+---------------------
+
+.. kernel-doc:: include/crypto/akcipher.h
+   :doc: Generic Public Key API
+
+.. kernel-doc:: include/crypto/akcipher.h
+   :functions: crypto_alloc_akcipher crypto_free_akcipher crypto_akcipher_set_pub_key crypto_akcipher_set_priv_key crypto_akcipher_maxsize crypto_akcipher_encrypt crypto_akcipher_decrypt crypto_akcipher_sign crypto_akcipher_verify
+
+Asymmetric Cipher Request Handle
+--------------------------------
+
+.. kernel-doc:: include/crypto/akcipher.h
+   :functions: akcipher_request_alloc akcipher_request_free akcipher_request_set_callback akcipher_request_set_crypt
diff --git a/Documentation/crypto/api-digest.rst b/Documentation/crypto/api-digest.rst
new file mode 100644
index 000000000..7a1e670d6
--- /dev/null
+++ b/Documentation/crypto/api-digest.rst
@@ -0,0 +1,35 @@
+Message Digest Algorithm Definitions
+------------------------------------
+
+.. kernel-doc:: include/crypto/hash.h
+   :doc: Message Digest Algorithm Definitions
+
+.. kernel-doc:: include/crypto/hash.h
+   :functions: hash_alg_common ahash_alg shash_alg
+
+Asynchronous Message Digest API
+-------------------------------
+
+.. kernel-doc:: include/crypto/hash.h
+   :doc: Asynchronous Message Digest API
+
+.. kernel-doc:: include/crypto/hash.h
+   :functions: crypto_alloc_ahash crypto_free_ahash crypto_ahash_init crypto_ahash_digestsize crypto_ahash_reqtfm crypto_ahash_reqsize crypto_ahash_statesize crypto_ahash_setkey crypto_ahash_finup crypto_ahash_final crypto_ahash_digest crypto_ahash_export crypto_ahash_import
+
+Asynchronous Hash Request Handle
+--------------------------------
+
+.. kernel-doc:: include/crypto/hash.h
+   :doc: Asynchronous Hash Request Handle
+
+.. kernel-doc:: include/crypto/hash.h
+   :functions: ahash_request_set_tfm ahash_request_alloc ahash_request_free ahash_request_set_callback ahash_request_set_crypt
+
+Synchronous Message Digest API
+------------------------------
+
+.. kernel-doc:: include/crypto/hash.h
+   :doc: Synchronous Message Digest API
+
+.. kernel-doc:: include/crypto/hash.h
+   :functions: crypto_alloc_shash crypto_free_shash crypto_shash_blocksize crypto_shash_digestsize crypto_shash_descsize crypto_shash_setkey crypto_shash_digest crypto_shash_export crypto_shash_import crypto_shash_init crypto_shash_update crypto_shash_final crypto_shash_finup
diff --git a/Documentation/crypto/api-intro.rst b/Documentation/crypto/api-intro.rst
new file mode 100644
index 000000000..15201be0b
--- /dev/null
+++ b/Documentation/crypto/api-intro.rst
@@ -0,0 +1,262 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============================
+Scatterlist Cryptographic API
+=============================
+
+Introduction
+============
+
+The Scatterlist Crypto API takes page vectors (scatterlists) as
+arguments, and works directly on pages.  In some cases (e.g. ECB
+mode ciphers), this will allow for pages to be encrypted in-place
+with no copying.
+
+One of the initial goals of this design was to readily support IPsec,
+so that processing can be applied to paged skb's without the need
+for linearization.
+
+
+Details
+=======
+
+At the lowest level are algorithms, which register dynamically with the
+API.
+
+'Transforms' are user-instantiated objects, which maintain state, handle all
+of the implementation logic (e.g. manipulating page vectors) and provide an
+abstraction to the underlying algorithms.  However, at the user
+level they are very simple.
+
+Conceptually, the API layering looks like this::
+
+  [transform api]  (user interface)
+  [transform ops]  (per-type logic glue e.g. cipher.c, compress.c)
+  [algorithm api]  (for registering algorithms)
+
+The idea is to make the user interface and algorithm registration API
+very simple, while hiding the core logic from both.  Many good ideas
+from existing APIs such as Cryptoapi and Nettle have been adapted for this.
+
+The API currently supports five main types of transforms: AEAD (Authenticated
+Encryption with Associated Data), Block Ciphers, Ciphers, Compressors and
+Hashes.
+
+Please note that Block Ciphers is somewhat of a misnomer.  It is in fact
+meant to support all ciphers including stream ciphers.  The difference
+between Block Ciphers and Ciphers is that the latter operates on exactly
+one block while the former can operate on an arbitrary amount of data,
+subject to block size requirements (i.e., non-stream ciphers can only
+process multiples of blocks).
+
+Here's an example of how to use the API::
+
+	#include <crypto/hash.h>
+	#include <linux/err.h>
+	#include <linux/scatterlist.h>
+
+	struct scatterlist sg[2];
+	char result[128];
+	struct crypto_ahash *tfm;
+	struct ahash_request *req;
+
+	tfm = crypto_alloc_ahash("md5", 0, CRYPTO_ALG_ASYNC);
+	if (IS_ERR(tfm))
+		fail();
+
+	/* ... set up the scatterlists ... */
+
+	req = ahash_request_alloc(tfm, GFP_ATOMIC);
+	if (!req)
+		fail();
+
+	ahash_request_set_callback(req, 0, NULL, NULL);
+	ahash_request_set_crypt(req, sg, result, 2);
+
+	if (crypto_ahash_digest(req))
+		fail();
+
+	ahash_request_free(req);
+	crypto_free_ahash(tfm);
+
+
+Many real examples are available in the regression test module (tcrypt.c).
+
+
+Developer Notes
+===============
+
+Transforms may only be allocated in user context, and cryptographic
+methods may only be called from softirq and user contexts.  For
+transforms with a setkey method it too should only be called from
+user context.
+
+When using the API for ciphers, performance will be optimal if each
+scatterlist contains data which is a multiple of the cipher's block
+size (typically 8 bytes).  This prevents having to do any copying
+across non-aligned page fragment boundaries.
+
+
+Adding New Algorithms
+=====================
+
+When submitting a new algorithm for inclusion, a mandatory requirement
+is that at least a few test vectors from known sources (preferably
+standards) be included.
+
+Converting existing well known code is preferred, as it is more likely
+to have been reviewed and widely tested.  If submitting code from LGPL
+sources, please consider changing the license to GPL (see section 3 of
+the LGPL).
+
+Algorithms submitted must also be generally patent-free (e.g. IDEA
+will not be included in the mainline until around 2011), and be based
+on a recognized standard and/or have been subjected to appropriate
+peer review.
+
+Also check for any RFCs which may relate to the use of specific algorithms,
+as well as general application notes such as RFC2451 ("The ESP CBC-Mode
+Cipher Algorithms").
+
+It's a good idea to avoid using lots of macros and use inlined functions
+instead, as gcc does a good job with inlining, while excessive use of
+macros can cause compilation problems on some platforms.
+
+Also check the TODO list at the web site listed below to see what people
+might already be working on.
+
+
+Bugs
+====
+
+Send bug reports to:
+    linux-crypto@vger.kernel.org
+
+Cc:
+    Herbert Xu <herbert@gondor.apana.org.au>,
+    David S. Miller <davem@redhat.com>
+
+
+Further Information
+===================
+
+For further patches and various updates, including the current TODO
+list, see:
+http://gondor.apana.org.au/~herbert/crypto/
+
+
+Authors
+=======
+
+- James Morris
+- David S. Miller
+- Herbert Xu
+
+
+Credits
+=======
+
+The following people provided invaluable feedback during the development
+of the API:
+
+  - Alexey Kuznetzov
+  - Rusty Russell
+  - Herbert Valerio Riedel
+  - Jeff Garzik
+  - Michael Richardson
+  - Andrew Morton
+  - Ingo Oeser
+  - Christoph Hellwig
+
+Portions of this API were derived from the following projects:
+
+  Kerneli Cryptoapi (http://www.kerneli.org/)
+   - Alexander Kjeldaas
+   - Herbert Valerio Riedel
+   - Kyle McMartin
+   - Jean-Luc Cooke
+   - David Bryson
+   - Clemens Fruhwirth
+   - Tobias Ringstrom
+   - Harald Welte
+
+and;
+
+  Nettle (https://www.lysator.liu.se/~nisse/nettle/)
+   - Niels Möller
+
+Original developers of the crypto algorithms:
+
+  - Dana L. How (DES)
+  - Andrew Tridgell and Steve French (MD4)
+  - Colin Plumb (MD5)
+  - Steve Reid (SHA1)
+  - Jean-Luc Cooke (SHA256, SHA384, SHA512)
+  - Kazunori Miyazawa / USAGI (HMAC)
+  - Matthew Skala (Twofish)
+  - Dag Arne Osvik (Serpent)
+  - Brian Gladman (AES)
+  - Kartikey Mahendra Bhatt (CAST6)
+  - Jon Oberheide (ARC4)
+  - Jouni Malinen (Michael MIC)
+  - NTT(Nippon Telegraph and Telephone Corporation) (Camellia)
+
+SHA1 algorithm contributors:
+  - Jean-Francois Dive
+
+DES algorithm contributors:
+  - Raimar Falke
+  - Gisle Sælensminde
+  - Niels Möller
+
+Blowfish algorithm contributors:
+  - Herbert Valerio Riedel
+  - Kyle McMartin
+
+Twofish algorithm contributors:
+  - Werner Koch
+  - Marc Mutz
+
+SHA256/384/512 algorithm contributors:
+  - Andrew McDonald
+  - Kyle McMartin
+  - Herbert Valerio Riedel
+
+AES algorithm contributors:
+  - Alexander Kjeldaas
+  - Herbert Valerio Riedel
+  - Kyle McMartin
+  - Adam J. Richter
+  - Fruhwirth Clemens (i586)
+  - Linus Torvalds (i586)
+
+CAST5 algorithm contributors:
+  - Kartikey Mahendra Bhatt (original developers unknown, FSF copyright).
+
+TEA/XTEA algorithm contributors:
+  - Aaron Grothe
+  - Michael Ringe
+
+Khazad algorithm contributors:
+  - Aaron Grothe
+
+Whirlpool algorithm contributors:
+  - Aaron Grothe
+  - Jean-Luc Cooke
+
+Anubis algorithm contributors:
+  - Aaron Grothe
+
+Tiger algorithm contributors:
+  - Aaron Grothe
+
+VIA PadLock contributors:
+  - Michal Ludvig
+
+Camellia algorithm contributors:
+  - NTT(Nippon Telegraph and Telephone Corporation) (Camellia)
+
+Generic scatterwalk code by Adam J. Richter <adam@yggdrasil.com>
+
+Please send any credits updates or corrections to:
+Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/Documentation/crypto/api-kpp.rst b/Documentation/crypto/api-kpp.rst
new file mode 100644
index 000000000..7d86ab906
--- /dev/null
+++ b/Documentation/crypto/api-kpp.rst
@@ -0,0 +1,38 @@
+Key-agreement Protocol Primitives (KPP) Cipher Algorithm Definitions
+--------------------------------------------------------------------
+
+.. kernel-doc:: include/crypto/kpp.h
+   :functions: kpp_request crypto_kpp kpp_alg kpp_secret
+
+Key-agreement Protocol Primitives (KPP) Cipher API
+--------------------------------------------------
+
+.. kernel-doc:: include/crypto/kpp.h
+   :doc: Generic Key-agreement Protocol Primitives API
+
+.. kernel-doc:: include/crypto/kpp.h
+   :functions: crypto_alloc_kpp crypto_free_kpp crypto_kpp_set_secret crypto_kpp_generate_public_key crypto_kpp_compute_shared_secret crypto_kpp_maxsize
+
+Key-agreement Protocol Primitives (KPP) Cipher Request Handle
+-------------------------------------------------------------
+
+.. kernel-doc:: include/crypto/kpp.h
+   :functions: kpp_request_alloc kpp_request_free kpp_request_set_callback kpp_request_set_input kpp_request_set_output
+
+ECDH Helper Functions
+---------------------
+
+.. kernel-doc:: include/crypto/ecdh.h
+   :doc: ECDH Helper Functions
+
+.. kernel-doc:: include/crypto/ecdh.h
+   :functions: ecdh crypto_ecdh_key_len crypto_ecdh_encode_key crypto_ecdh_decode_key
+
+DH Helper Functions
+-------------------
+
+.. kernel-doc:: include/crypto/dh.h
+   :doc: DH Helper Functions
+
+.. kernel-doc:: include/crypto/dh.h
+   :functions: dh crypto_dh_key_len crypto_dh_encode_key crypto_dh_decode_key
diff --git a/Documentation/crypto/api-rng.rst b/Documentation/crypto/api-rng.rst
new file mode 100644
index 000000000..10ba7436c
--- /dev/null
+++ b/Documentation/crypto/api-rng.rst
@@ -0,0 +1,14 @@
+Random Number Algorithm Definitions
+-----------------------------------
+
+.. kernel-doc:: include/crypto/rng.h
+   :functions: rng_alg
+
+Crypto API Random Number API
+----------------------------
+
+.. kernel-doc:: include/crypto/rng.h
+   :doc: Random number generator API
+
+.. kernel-doc:: include/crypto/rng.h
+   :functions: crypto_alloc_rng crypto_rng_alg crypto_free_rng crypto_rng_generate crypto_rng_get_bytes crypto_rng_reset crypto_rng_seedsize
diff --git a/Documentation/crypto/api-samples.rst b/Documentation/crypto/api-samples.rst
new file mode 100644
index 000000000..e923f17bc
--- /dev/null
+++ b/Documentation/crypto/api-samples.rst
@@ -0,0 +1,187 @@
+Code Examples
+=============
+
+Code Example For Symmetric Key Cipher Operation
+-----------------------------------------------
+
+This code encrypts some data with AES-256-XTS.  For sake of example,
+all inputs are random bytes, the encryption is done in-place, and it's
+assumed the code is running in a context where it can sleep.
+
+::
+
+    static int test_skcipher(void)
+    {
+            struct crypto_skcipher *tfm = NULL;
+            struct skcipher_request *req = NULL;
+            u8 *data = NULL;
+            const size_t datasize = 512; /* data size in bytes */
+            struct scatterlist sg;
+            DECLARE_CRYPTO_WAIT(wait);
+            u8 iv[16];  /* AES-256-XTS takes a 16-byte IV */
+            u8 key[64]; /* AES-256-XTS takes a 64-byte key */
+            int err;
+
+            /*
+             * Allocate a tfm (a transformation object) and set the key.
+             *
+             * In real-world use, a tfm and key are typically used for many
+             * encryption/decryption operations.  But in this example, we'll just do a
+             * single encryption operation with it (which is not very efficient).
+             */
+
+            tfm = crypto_alloc_skcipher("xts(aes)", 0, 0);
+            if (IS_ERR(tfm)) {
+                    pr_err("Error allocating xts(aes) handle: %ld\n", PTR_ERR(tfm));
+                    return PTR_ERR(tfm);
+            }
+
+            get_random_bytes(key, sizeof(key));
+            err = crypto_skcipher_setkey(tfm, key, sizeof(key));
+            if (err) {
+                    pr_err("Error setting key: %d\n", err);
+                    goto out;
+            }
+
+            /* Allocate a request object */
+            req = skcipher_request_alloc(tfm, GFP_KERNEL);
+            if (!req) {
+                    err = -ENOMEM;
+                    goto out;
+            }
+
+            /* Prepare the input data */
+            data = kmalloc(datasize, GFP_KERNEL);
+            if (!data) {
+                    err = -ENOMEM;
+                    goto out;
+            }
+            get_random_bytes(data, datasize);
+
+            /* Initialize the IV */
+            get_random_bytes(iv, sizeof(iv));
+
+            /*
+             * Encrypt the data in-place.
+             *
+             * For simplicity, in this example we wait for the request to complete
+             * before proceeding, even if the underlying implementation is asynchronous.
+             *
+             * To decrypt instead of encrypt, just change crypto_skcipher_encrypt() to
+             * crypto_skcipher_decrypt().
+             */
+            sg_init_one(&sg, data, datasize);
+            skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
+                                               CRYPTO_TFM_REQ_MAY_SLEEP,
+                                          crypto_req_done, &wait);
+            skcipher_request_set_crypt(req, &sg, &sg, datasize, iv);
+            err = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
+            if (err) {
+                    pr_err("Error encrypting data: %d\n", err);
+                    goto out;
+            }
+
+            pr_debug("Encryption was successful\n");
+    out:
+            crypto_free_skcipher(tfm);
+            skcipher_request_free(req);
+            kfree(data);
+            return err;
+    }
+
+
+Code Example For Use of Operational State Memory With SHASH
+-----------------------------------------------------------
+
+::
+
+
+    struct sdesc {
+        struct shash_desc shash;
+        char ctx[];
+    };
+
+    static struct sdesc *init_sdesc(struct crypto_shash *alg)
+    {
+        struct sdesc *sdesc;
+        int size;
+
+        size = sizeof(struct shash_desc) + crypto_shash_descsize(alg);
+        sdesc = kmalloc(size, GFP_KERNEL);
+        if (!sdesc)
+            return ERR_PTR(-ENOMEM);
+        sdesc->shash.tfm = alg;
+        return sdesc;
+    }
+
+    static int calc_hash(struct crypto_shash *alg,
+                 const unsigned char *data, unsigned int datalen,
+                 unsigned char *digest)
+    {
+        struct sdesc *sdesc;
+        int ret;
+
+        sdesc = init_sdesc(alg);
+        if (IS_ERR(sdesc)) {
+            pr_info("can't alloc sdesc\n");
+            return PTR_ERR(sdesc);
+        }
+
+        ret = crypto_shash_digest(&sdesc->shash, data, datalen, digest);
+        kfree(sdesc);
+        return ret;
+    }
+
+    static int test_hash(const unsigned char *data, unsigned int datalen,
+                 unsigned char *digest)
+    {
+        struct crypto_shash *alg;
+        char *hash_alg_name = "sha1-padlock-nano";
+        int ret;
+
+        alg = crypto_alloc_shash(hash_alg_name, 0, 0);
+        if (IS_ERR(alg)) {
+                pr_info("can't alloc alg %s\n", hash_alg_name);
+                return PTR_ERR(alg);
+        }
+        ret = calc_hash(alg, data, datalen, digest);
+        crypto_free_shash(alg);
+        return ret;
+    }
+
+
+Code Example For Random Number Generator Usage
+----------------------------------------------
+
+::
+
+
+    static int get_random_numbers(u8 *buf, unsigned int len)
+    {
+        struct crypto_rng *rng = NULL;
+        char *drbg = "drbg_nopr_sha256"; /* Hash DRBG with SHA-256, no PR */
+        int ret;
+
+        if (!buf || !len) {
+            pr_debug("No output buffer provided\n");
+            return -EINVAL;
+        }
+
+        rng = crypto_alloc_rng(drbg, 0, 0);
+        if (IS_ERR(rng)) {
+            pr_debug("could not allocate RNG handle for %s\n", drbg);
+            return PTR_ERR(rng);
+        }
+
+        ret = crypto_rng_get_bytes(rng, buf, len);
+        if (ret < 0)
+            pr_debug("generation of random numbers failed\n");
+        else if (ret == 0)
+            pr_debug("RNG returned no data");
+        else
+            pr_debug("RNG returned %d bytes of data\n", ret);
+
+    out:
+        crypto_free_rng(rng);
+        return ret;
+    }
diff --git a/Documentation/crypto/api-skcipher.rst b/Documentation/crypto/api-skcipher.rst
new file mode 100644
index 000000000..04d6cc535
--- /dev/null
+++ b/Documentation/crypto/api-skcipher.rst
@@ -0,0 +1,35 @@
+Block Cipher Algorithm Definitions
+----------------------------------
+
+.. kernel-doc:: include/linux/crypto.h
+   :doc: Block Cipher Algorithm Definitions
+
+.. kernel-doc:: include/linux/crypto.h
+   :functions: crypto_alg cipher_alg compress_alg
+
+Symmetric Key Cipher API
+------------------------
+
+.. kernel-doc:: include/crypto/skcipher.h
+   :doc: Symmetric Key Cipher API
+
+.. kernel-doc:: include/crypto/skcipher.h
+   :functions: crypto_alloc_skcipher crypto_free_skcipher crypto_has_skcipher crypto_skcipher_ivsize crypto_skcipher_blocksize crypto_skcipher_setkey crypto_skcipher_reqtfm crypto_skcipher_encrypt crypto_skcipher_decrypt
+
+Symmetric Key Cipher Request Handle
+-----------------------------------
+
+.. kernel-doc:: include/crypto/skcipher.h
+   :doc: Symmetric Key Cipher Request Handle
+
+.. kernel-doc:: include/crypto/skcipher.h
+   :functions: crypto_skcipher_reqsize skcipher_request_set_tfm skcipher_request_alloc skcipher_request_free skcipher_request_set_callback skcipher_request_set_crypt
+
+Single Block Cipher API
+-----------------------
+
+.. kernel-doc:: include/crypto/internal/cipher.h
+   :doc: Single Block Cipher API
+
+.. kernel-doc:: include/crypto/internal/cipher.h
+   :functions: crypto_alloc_cipher crypto_free_cipher crypto_has_cipher crypto_cipher_blocksize crypto_cipher_setkey crypto_cipher_encrypt_one crypto_cipher_decrypt_one
diff --git a/Documentation/crypto/api.rst b/Documentation/crypto/api.rst
new file mode 100644
index 000000000..b91b31736
--- /dev/null
+++ b/Documentation/crypto/api.rst
@@ -0,0 +1,16 @@
+Programming Interface
+=====================
+
+.. class:: toc-title
+
+	   Table of contents
+
+.. toctree::
+   :maxdepth: 2
+
+   api-skcipher
+   api-aead
+   api-digest
+   api-rng
+   api-akcipher
+   api-kpp
diff --git a/Documentation/crypto/architecture.rst b/Documentation/crypto/architecture.rst
new file mode 100644
index 000000000..646c3380a
--- /dev/null
+++ b/Documentation/crypto/architecture.rst
@@ -0,0 +1,414 @@
+Kernel Crypto API Architecture
+==============================
+
+Cipher algorithm types
+----------------------
+
+The kernel crypto API provides different API calls for the following
+cipher types:
+
+-  Symmetric ciphers
+
+-  AEAD ciphers
+
+-  Message digest, including keyed message digest
+
+-  Random number generation
+
+-  User space interface
+
+Ciphers And Templates
+---------------------
+
+The kernel crypto API provides implementations of single block ciphers
+and message digests. In addition, the kernel crypto API provides
+numerous "templates" that can be used in conjunction with the single
+block ciphers and message digests. Templates include all types of block
+chaining mode, the HMAC mechanism, etc.
+
+Single block ciphers and message digests can either be directly used by
+a caller or invoked together with a template to form multi-block ciphers
+or keyed message digests.
+
+A single block cipher may even be called with multiple templates.
+However, templates cannot be used without a single cipher.
+
+See /proc/crypto and search for "name". For example:
+
+-  aes
+
+-  ecb(aes)
+
+-  cmac(aes)
+
+-  ccm(aes)
+
+-  rfc4106(gcm(aes))
+
+-  sha1
+
+-  hmac(sha1)
+
+-  authenc(hmac(sha1),cbc(aes))
+
+In these examples, "aes" and "sha1" are the ciphers and all others are
+the templates.
+
+Synchronous And Asynchronous Operation
+--------------------------------------
+
+The kernel crypto API provides synchronous and asynchronous API
+operations.
+
+When using the synchronous API operation, the caller invokes a cipher
+operation which is performed synchronously by the kernel crypto API.
+That means, the caller waits until the cipher operation completes.
+Therefore, the kernel crypto API calls work like regular function calls.
+For synchronous operation, the set of API calls is small and
+conceptually similar to any other crypto library.
+
+Asynchronous operation is provided by the kernel crypto API which
+implies that the invocation of a cipher operation will complete almost
+instantly. That invocation triggers the cipher operation but it does not
+signal its completion. Before invoking a cipher operation, the caller
+must provide a callback function the kernel crypto API can invoke to
+signal the completion of the cipher operation. Furthermore, the caller
+must ensure it can handle such asynchronous events by applying
+appropriate locking around its data. The kernel crypto API does not
+perform any special serialization operation to protect the caller's data
+integrity.
+
+Crypto API Cipher References And Priority
+-----------------------------------------
+
+A cipher is referenced by the caller with a string. That string has the
+following semantics:
+
+::
+
+        template(single block cipher)
+
+
+where "template" and "single block cipher" is the aforementioned
+template and single block cipher, respectively. If applicable,
+additional templates may enclose other templates, such as
+
+::
+
+        template1(template2(single block cipher)))
+
+
+The kernel crypto API may provide multiple implementations of a template
+or a single block cipher. For example, AES on newer Intel hardware has
+the following implementations: AES-NI, assembler implementation, or
+straight C. Now, when using the string "aes" with the kernel crypto API,
+which cipher implementation is used? The answer to that question is the
+priority number assigned to each cipher implementation by the kernel
+crypto API. When a caller uses the string to refer to a cipher during
+initialization of a cipher handle, the kernel crypto API looks up all
+implementations providing an implementation with that name and selects
+the implementation with the highest priority.
+
+Now, a caller may have the need to refer to a specific cipher
+implementation and thus does not want to rely on the priority-based
+selection. To accommodate this scenario, the kernel crypto API allows
+the cipher implementation to register a unique name in addition to
+common names. When using that unique name, a caller is therefore always
+sure to refer to the intended cipher implementation.
+
+The list of available ciphers is given in /proc/crypto. However, that
+list does not specify all possible permutations of templates and
+ciphers. Each block listed in /proc/crypto may contain the following
+information -- if one of the components listed as follows are not
+applicable to a cipher, it is not displayed:
+
+-  name: the generic name of the cipher that is subject to the
+   priority-based selection -- this name can be used by the cipher
+   allocation API calls (all names listed above are examples for such
+   generic names)
+
+-  driver: the unique name of the cipher -- this name can be used by the
+   cipher allocation API calls
+
+-  module: the kernel module providing the cipher implementation (or
+   "kernel" for statically linked ciphers)
+
+-  priority: the priority value of the cipher implementation
+
+-  refcnt: the reference count of the respective cipher (i.e. the number
+   of current consumers of this cipher)
+
+-  selftest: specification whether the self test for the cipher passed
+
+-  type:
+
+   -  skcipher for symmetric key ciphers
+
+   -  cipher for single block ciphers that may be used with an
+      additional template
+
+   -  shash for synchronous message digest
+
+   -  ahash for asynchronous message digest
+
+   -  aead for AEAD cipher type
+
+   -  compression for compression type transformations
+
+   -  rng for random number generator
+
+   -  kpp for a Key-agreement Protocol Primitive (KPP) cipher such as
+      an ECDH or DH implementation
+
+-  blocksize: blocksize of cipher in bytes
+
+-  keysize: key size in bytes
+
+-  ivsize: IV size in bytes
+
+-  seedsize: required size of seed data for random number generator
+
+-  digestsize: output size of the message digest
+
+-  geniv: IV generator (obsolete)
+
+Key Sizes
+---------
+
+When allocating a cipher handle, the caller only specifies the cipher
+type. Symmetric ciphers, however, typically support multiple key sizes
+(e.g. AES-128 vs. AES-192 vs. AES-256). These key sizes are determined
+with the length of the provided key. Thus, the kernel crypto API does
+not provide a separate way to select the particular symmetric cipher key
+size.
+
+Cipher Allocation Type And Masks
+--------------------------------
+
+The different cipher handle allocation functions allow the specification
+of a type and mask flag. Both parameters have the following meaning (and
+are therefore not covered in the subsequent sections).
+
+The type flag specifies the type of the cipher algorithm. The caller
+usually provides a 0 when the caller wants the default handling.
+Otherwise, the caller may provide the following selections which match
+the aforementioned cipher types:
+
+-  CRYPTO_ALG_TYPE_CIPHER Single block cipher
+
+-  CRYPTO_ALG_TYPE_COMPRESS Compression
+
+-  CRYPTO_ALG_TYPE_AEAD Authenticated Encryption with Associated Data
+   (MAC)
+
+-  CRYPTO_ALG_TYPE_KPP Key-agreement Protocol Primitive (KPP) such as
+   an ECDH or DH implementation
+
+-  CRYPTO_ALG_TYPE_HASH Raw message digest
+
+-  CRYPTO_ALG_TYPE_SHASH Synchronous multi-block hash
+
+-  CRYPTO_ALG_TYPE_AHASH Asynchronous multi-block hash
+
+-  CRYPTO_ALG_TYPE_RNG Random Number Generation
+
+-  CRYPTO_ALG_TYPE_AKCIPHER Asymmetric cipher
+
+-  CRYPTO_ALG_TYPE_PCOMPRESS Enhanced version of
+   CRYPTO_ALG_TYPE_COMPRESS allowing for segmented compression /
+   decompression instead of performing the operation on one segment
+   only. CRYPTO_ALG_TYPE_PCOMPRESS is intended to replace
+   CRYPTO_ALG_TYPE_COMPRESS once existing consumers are converted.
+
+The mask flag restricts the type of cipher. The only allowed flag is
+CRYPTO_ALG_ASYNC to restrict the cipher lookup function to
+asynchronous ciphers. Usually, a caller provides a 0 for the mask flag.
+
+When the caller provides a mask and type specification, the caller
+limits the search the kernel crypto API can perform for a suitable
+cipher implementation for the given cipher name. That means, even when a
+caller uses a cipher name that exists during its initialization call,
+the kernel crypto API may not select it due to the used type and mask
+field.
+
+Internal Structure of Kernel Crypto API
+---------------------------------------
+
+The kernel crypto API has an internal structure where a cipher
+implementation may use many layers and indirections. This section shall
+help to clarify how the kernel crypto API uses various components to
+implement the complete cipher.
+
+The following subsections explain the internal structure based on
+existing cipher implementations. The first section addresses the most
+complex scenario where all other scenarios form a logical subset.
+
+Generic AEAD Cipher Structure
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following ASCII art decomposes the kernel crypto API layers when
+using the AEAD cipher with the automated IV generation. The shown
+example is used by the IPSEC layer.
+
+For other use cases of AEAD ciphers, the ASCII art applies as well, but
+the caller may not use the AEAD cipher with a separate IV generator. In
+this case, the caller must generate the IV.
+
+The depicted example decomposes the AEAD cipher of GCM(AES) based on the
+generic C implementations (gcm.c, aes-generic.c, ctr.c, ghash-generic.c,
+seqiv.c). The generic implementation serves as an example showing the
+complete logic of the kernel crypto API.
+
+It is possible that some streamlined cipher implementations (like
+AES-NI) provide implementations merging aspects which in the view of the
+kernel crypto API cannot be decomposed into layers any more. In case of
+the AES-NI implementation, the CTR mode, the GHASH implementation and
+the AES cipher are all merged into one cipher implementation registered
+with the kernel crypto API. In this case, the concept described by the
+following ASCII art applies too. However, the decomposition of GCM into
+the individual sub-components by the kernel crypto API is not done any
+more.
+
+Each block in the following ASCII art is an independent cipher instance
+obtained from the kernel crypto API. Each block is accessed by the
+caller or by other blocks using the API functions defined by the kernel
+crypto API for the cipher implementation type.
+
+The blocks below indicate the cipher type as well as the specific logic
+implemented in the cipher.
+
+The ASCII art picture also indicates the call structure, i.e. who calls
+which component. The arrows point to the invoked block where the caller
+uses the API applicable to the cipher type specified for the block.
+
+::
+
+
+    kernel crypto API                                |   IPSEC Layer
+                                                     |
+    +-----------+                                    |
+    |           |            (1)
+    |   aead    | <-----------------------------------  esp_output
+    |  (seqiv)  | ---+
+    +-----------+    |
+                     | (2)
+    +-----------+    |
+    |           | <--+                (2)
+    |   aead    | <-----------------------------------  esp_input
+    |   (gcm)   | ------------+
+    +-----------+             |
+          | (3)               | (5)
+          v                   v
+    +-----------+       +-----------+
+    |           |       |           |
+    |  skcipher |       |   ahash   |
+    |   (ctr)   | ---+  |  (ghash)  |
+    +-----------+    |  +-----------+
+                     |
+    +-----------+    | (4)
+    |           | <--+
+    |   cipher  |
+    |   (aes)   |
+    +-----------+
+
+
+
+The following call sequence is applicable when the IPSEC layer triggers
+an encryption operation with the esp_output function. During
+configuration, the administrator set up the use of seqiv(rfc4106(gcm(aes)))
+as the cipher for ESP. The following call sequence is now depicted in
+the ASCII art above:
+
+1. esp_output() invokes crypto_aead_encrypt() to trigger an
+   encryption operation of the AEAD cipher with IV generator.
+
+   The SEQIV generates the IV.
+
+2. Now, SEQIV uses the AEAD API function calls to invoke the associated
+   AEAD cipher. In our case, during the instantiation of SEQIV, the
+   cipher handle for GCM is provided to SEQIV. This means that SEQIV
+   invokes AEAD cipher operations with the GCM cipher handle.
+
+   During instantiation of the GCM handle, the CTR(AES) and GHASH
+   ciphers are instantiated. The cipher handles for CTR(AES) and GHASH
+   are retained for later use.
+
+   The GCM implementation is responsible to invoke the CTR mode AES and
+   the GHASH cipher in the right manner to implement the GCM
+   specification.
+
+3. The GCM AEAD cipher type implementation now invokes the SKCIPHER API
+   with the instantiated CTR(AES) cipher handle.
+
+   During instantiation of the CTR(AES) cipher, the CIPHER type
+   implementation of AES is instantiated. The cipher handle for AES is
+   retained.
+
+   That means that the SKCIPHER implementation of CTR(AES) only
+   implements the CTR block chaining mode. After performing the block
+   chaining operation, the CIPHER implementation of AES is invoked.
+
+4. The SKCIPHER of CTR(AES) now invokes the CIPHER API with the AES
+   cipher handle to encrypt one block.
+
+5. The GCM AEAD implementation also invokes the GHASH cipher
+   implementation via the AHASH API.
+
+When the IPSEC layer triggers the esp_input() function, the same call
+sequence is followed with the only difference that the operation starts
+with step (2).
+
+Generic Block Cipher Structure
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Generic block ciphers follow the same concept as depicted with the ASCII
+art picture above.
+
+For example, CBC(AES) is implemented with cbc.c, and aes-generic.c. The
+ASCII art picture above applies as well with the difference that only
+step (4) is used and the SKCIPHER block chaining mode is CBC.
+
+Generic Keyed Message Digest Structure
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Keyed message digest implementations again follow the same concept as
+depicted in the ASCII art picture above.
+
+For example, HMAC(SHA256) is implemented with hmac.c and
+sha256_generic.c. The following ASCII art illustrates the
+implementation:
+
+::
+
+
+    kernel crypto API            |       Caller
+                                 |
+    +-----------+         (1)    |
+    |           | <------------------  some_function
+    |   ahash   |
+    |   (hmac)  | ---+
+    +-----------+    |
+                     | (2)
+    +-----------+    |
+    |           | <--+
+    |   shash   |
+    |  (sha256) |
+    +-----------+
+
+
+
+The following call sequence is applicable when a caller triggers an HMAC
+operation:
+
+1. The AHASH API functions are invoked by the caller. The HMAC
+   implementation performs its operation as needed.
+
+   During initialization of the HMAC cipher, the SHASH cipher type of
+   SHA256 is instantiated. The cipher handle for the SHA256 instance is
+   retained.
+
+   At one time, the HMAC implementation requires a SHA256 operation
+   where the SHA256 cipher handle is used.
+
+2. The HMAC instance now invokes the SHASH API with the SHA256 cipher
+   handle to calculate the message digest.
diff --git a/Documentation/crypto/asymmetric-keys.rst b/Documentation/crypto/asymmetric-keys.rst
new file mode 100644
index 000000000..349f44a29
--- /dev/null
+++ b/Documentation/crypto/asymmetric-keys.rst
@@ -0,0 +1,424 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============================================
+Asymmetric / Public-key Cryptography Key Type
+=============================================
+
+.. Contents:
+
+  - Overview.
+  - Key identification.
+  - Accessing asymmetric keys.
+    - Signature verification.
+  - Asymmetric key subtypes.
+  - Instantiation data parsers.
+  - Keyring link restrictions.
+
+
+Overview
+========
+
+The "asymmetric" key type is designed to be a container for the keys used in
+public-key cryptography, without imposing any particular restrictions on the
+form or mechanism of the cryptography or form of the key.
+
+The asymmetric key is given a subtype that defines what sort of data is
+associated with the key and provides operations to describe and destroy it.
+However, no requirement is made that the key data actually be stored in the
+key.
+
+A completely in-kernel key retention and operation subtype can be defined, but
+it would also be possible to provide access to cryptographic hardware (such as
+a TPM) that might be used to both retain the relevant key and perform
+operations using that key.  In such a case, the asymmetric key would then
+merely be an interface to the TPM driver.
+
+Also provided is the concept of a data parser.  Data parsers are responsible
+for extracting information from the blobs of data passed to the instantiation
+function.  The first data parser that recognises the blob gets to set the
+subtype of the key and define the operations that can be done on that key.
+
+A data parser may interpret the data blob as containing the bits representing a
+key, or it may interpret it as a reference to a key held somewhere else in the
+system (for example, a TPM).
+
+
+Key Identification
+==================
+
+If a key is added with an empty name, the instantiation data parsers are given
+the opportunity to pre-parse a key and to determine the description the key
+should be given from the content of the key.
+
+This can then be used to refer to the key, either by complete match or by
+partial match.  The key type may also use other criteria to refer to a key.
+
+The asymmetric key type's match function can then perform a wider range of
+comparisons than just the straightforward comparison of the description with
+the criterion string:
+
+  1) If the criterion string is of the form "id:<hexdigits>" then the match
+     function will examine a key's fingerprint to see if the hex digits given
+     after the "id:" match the tail.  For instance::
+
+	keyctl search @s asymmetric id:5acc2142
+
+     will match a key with fingerprint::
+
+	1A00 2040 7601 7889 DE11  882C 3823 04AD 5ACC 2142
+
+  2) If the criterion string is of the form "<subtype>:<hexdigits>" then the
+     match will match the ID as in (1), but with the added restriction that
+     only keys of the specified subtype (e.g. tpm) will be matched.  For
+     instance::
+
+	keyctl search @s asymmetric tpm:5acc2142
+
+Looking in /proc/keys, the last 8 hex digits of the key fingerprint are
+displayed, along with the subtype::
+
+	1a39e171 I-----     1 perm 3f010000     0     0 asymmetric modsign.0: DSA 5acc2142 []
+
+
+Accessing Asymmetric Keys
+=========================
+
+For general access to asymmetric keys from within the kernel, the following
+inclusion is required::
+
+	#include <crypto/public_key.h>
+
+This gives access to functions for dealing with asymmetric / public keys.
+Three enums are defined there for representing public-key cryptography
+algorithms::
+
+	enum pkey_algo
+
+digest algorithms used by those::
+
+	enum pkey_hash_algo
+
+and key identifier representations::
+
+	enum pkey_id_type
+
+Note that the key type representation types are required because key
+identifiers from different standards aren't necessarily compatible.  For
+instance, PGP generates key identifiers by hashing the key data plus some
+PGP-specific metadata, whereas X.509 has arbitrary certificate identifiers.
+
+The operations defined upon a key are:
+
+  1) Signature verification.
+
+Other operations are possible (such as encryption) with the same key data
+required for verification, but not currently supported, and others
+(eg. decryption and signature generation) require extra key data.
+
+
+Signature Verification
+----------------------
+
+An operation is provided to perform cryptographic signature verification, using
+an asymmetric key to provide or to provide access to the public key::
+
+	int verify_signature(const struct key *key,
+			     const struct public_key_signature *sig);
+
+The caller must have already obtained the key from some source and can then use
+it to check the signature.  The caller must have parsed the signature and
+transferred the relevant bits to the structure pointed to by sig::
+
+	struct public_key_signature {
+		u8 *digest;
+		u8 digest_size;
+		enum pkey_hash_algo pkey_hash_algo : 8;
+		u8 nr_mpi;
+		union {
+			MPI mpi[2];
+			...
+		};
+	};
+
+The algorithm used must be noted in sig->pkey_hash_algo, and all the MPIs that
+make up the actual signature must be stored in sig->mpi[] and the count of MPIs
+placed in sig->nr_mpi.
+
+In addition, the data must have been digested by the caller and the resulting
+hash must be pointed to by sig->digest and the size of the hash be placed in
+sig->digest_size.
+
+The function will return 0 upon success or -EKEYREJECTED if the signature
+doesn't match.
+
+The function may also return -ENOTSUPP if an unsupported public-key algorithm
+or public-key/hash algorithm combination is specified or the key doesn't
+support the operation; -EBADMSG or -ERANGE if some of the parameters have weird
+data; or -ENOMEM if an allocation can't be performed.  -EINVAL can be returned
+if the key argument is the wrong type or is incompletely set up.
+
+
+Asymmetric Key Subtypes
+=======================
+
+Asymmetric keys have a subtype that defines the set of operations that can be
+performed on that key and that determines what data is attached as the key
+payload.  The payload format is entirely at the whim of the subtype.
+
+The subtype is selected by the key data parser and the parser must initialise
+the data required for it.  The asymmetric key retains a reference on the
+subtype module.
+
+The subtype definition structure can be found in::
+
+	#include <keys/asymmetric-subtype.h>
+
+and looks like the following::
+
+	struct asymmetric_key_subtype {
+		struct module		*owner;
+		const char		*name;
+
+		void (*describe)(const struct key *key, struct seq_file *m);
+		void (*destroy)(void *payload);
+		int (*query)(const struct kernel_pkey_params *params,
+			     struct kernel_pkey_query *info);
+		int (*eds_op)(struct kernel_pkey_params *params,
+			      const void *in, void *out);
+		int (*verify_signature)(const struct key *key,
+					const struct public_key_signature *sig);
+	};
+
+Asymmetric keys point to this with their payload[asym_subtype] member.
+
+The owner and name fields should be set to the owning module and the name of
+the subtype.  Currently, the name is only used for print statements.
+
+There are a number of operations defined by the subtype:
+
+  1) describe().
+
+     Mandatory.  This allows the subtype to display something in /proc/keys
+     against the key.  For instance the name of the public key algorithm type
+     could be displayed.  The key type will display the tail of the key
+     identity string after this.
+
+  2) destroy().
+
+     Mandatory.  This should free the memory associated with the key.  The
+     asymmetric key will look after freeing the fingerprint and releasing the
+     reference on the subtype module.
+
+  3) query().
+
+     Mandatory.  This is a function for querying the capabilities of a key.
+
+  4) eds_op().
+
+     Optional.  This is the entry point for the encryption, decryption and
+     signature creation operations (which are distinguished by the operation ID
+     in the parameter struct).  The subtype may do anything it likes to
+     implement an operation, including offloading to hardware.
+
+  5) verify_signature().
+
+     Optional.  This is the entry point for signature verification.  The
+     subtype may do anything it likes to implement an operation, including
+     offloading to hardware.
+
+Instantiation Data Parsers
+==========================
+
+The asymmetric key type doesn't generally want to store or to deal with a raw
+blob of data that holds the key data.  It would have to parse it and error
+check it each time it wanted to use it.  Further, the contents of the blob may
+have various checks that can be performed on it (eg. self-signatures, validity
+dates) and may contain useful data about the key (identifiers, capabilities).
+
+Also, the blob may represent a pointer to some hardware containing the key
+rather than the key itself.
+
+Examples of blob formats for which parsers could be implemented include:
+
+ - OpenPGP packet stream [RFC 4880].
+ - X.509 ASN.1 stream.
+ - Pointer to TPM key.
+ - Pointer to UEFI key.
+ - PKCS#8 private key [RFC 5208].
+ - PKCS#5 encrypted private key [RFC 2898].
+
+During key instantiation each parser in the list is tried until one doesn't
+return -EBADMSG.
+
+The parser definition structure can be found in::
+
+	#include <keys/asymmetric-parser.h>
+
+and looks like the following::
+
+	struct asymmetric_key_parser {
+		struct module	*owner;
+		const char	*name;
+
+		int (*parse)(struct key_preparsed_payload *prep);
+	};
+
+The owner and name fields should be set to the owning module and the name of
+the parser.
+
+There is currently only a single operation defined by the parser, and it is
+mandatory:
+
+  1) parse().
+
+     This is called to preparse the key from the key creation and update paths.
+     In particular, it is called during the key creation _before_ a key is
+     allocated, and as such, is permitted to provide the key's description in
+     the case that the caller declines to do so.
+
+     The caller passes a pointer to the following struct with all of the fields
+     cleared, except for data, datalen and quotalen [see
+     Documentation/security/keys/core.rst]::
+
+	struct key_preparsed_payload {
+		char		*description;
+		void		*payload[4];
+		const void	*data;
+		size_t		datalen;
+		size_t		quotalen;
+	};
+
+     The instantiation data is in a blob pointed to by data and is datalen in
+     size.  The parse() function is not permitted to change these two values at
+     all, and shouldn't change any of the other values _unless_ they are
+     recognise the blob format and will not return -EBADMSG to indicate it is
+     not theirs.
+
+     If the parser is happy with the blob, it should propose a description for
+     the key and attach it to ->description, ->payload[asym_subtype] should be
+     set to point to the subtype to be used, ->payload[asym_crypto] should be
+     set to point to the initialised data for that subtype,
+     ->payload[asym_key_ids] should point to one or more hex fingerprints and
+     quotalen should be updated to indicate how much quota this key should
+     account for.
+
+     When clearing up, the data attached to ->payload[asym_key_ids] and
+     ->description will be kfree()'d and the data attached to
+     ->payload[asm_crypto] will be passed to the subtype's ->destroy() method
+     to be disposed of.  A module reference for the subtype pointed to by
+     ->payload[asym_subtype] will be put.
+
+
+     If the data format is not recognised, -EBADMSG should be returned.  If it
+     is recognised, but the key cannot for some reason be set up, some other
+     negative error code should be returned.  On success, 0 should be returned.
+
+     The key's fingerprint string may be partially matched upon.  For a
+     public-key algorithm such as RSA and DSA this will likely be a printable
+     hex version of the key's fingerprint.
+
+Functions are provided to register and unregister parsers::
+
+	int register_asymmetric_key_parser(struct asymmetric_key_parser *parser);
+	void unregister_asymmetric_key_parser(struct asymmetric_key_parser *subtype);
+
+Parsers may not have the same name.  The names are otherwise only used for
+displaying in debugging messages.
+
+
+Keyring Link Restrictions
+=========================
+
+Keyrings created from userspace using add_key can be configured to check the
+signature of the key being linked.  Keys without a valid signature are not
+allowed to link.
+
+Several restriction methods are available:
+
+  1) Restrict using the kernel builtin trusted keyring
+
+     - Option string used with KEYCTL_RESTRICT_KEYRING:
+       - "builtin_trusted"
+
+     The kernel builtin trusted keyring will be searched for the signing key.
+     If the builtin trusted keyring is not configured, all links will be
+     rejected.  The ca_keys kernel parameter also affects which keys are used
+     for signature verification.
+
+  2) Restrict using the kernel builtin and secondary trusted keyrings
+
+     - Option string used with KEYCTL_RESTRICT_KEYRING:
+       - "builtin_and_secondary_trusted"
+
+     The kernel builtin and secondary trusted keyrings will be searched for the
+     signing key.  If the secondary trusted keyring is not configured, this
+     restriction will behave like the "builtin_trusted" option.  The ca_keys
+     kernel parameter also affects which keys are used for signature
+     verification.
+
+  3) Restrict using a separate key or keyring
+
+     - Option string used with KEYCTL_RESTRICT_KEYRING:
+       - "key_or_keyring:<key or keyring serial number>[:chain]"
+
+     Whenever a key link is requested, the link will only succeed if the key
+     being linked is signed by one of the designated keys.  This key may be
+     specified directly by providing a serial number for one asymmetric key, or
+     a group of keys may be searched for the signing key by providing the
+     serial number for a keyring.
+
+     When the "chain" option is provided at the end of the string, the keys
+     within the destination keyring will also be searched for signing keys.
+     This allows for verification of certificate chains by adding each
+     certificate in order (starting closest to the root) to a keyring.  For
+     instance, one keyring can be populated with links to a set of root
+     certificates, with a separate, restricted keyring set up for each
+     certificate chain to be validated::
+
+	# Create and populate a keyring for root certificates
+	root_id=`keyctl add keyring root-certs "" @s`
+	keyctl padd asymmetric "" $root_id < root1.cert
+	keyctl padd asymmetric "" $root_id < root2.cert
+
+	# Create and restrict a keyring for the certificate chain
+	chain_id=`keyctl add keyring chain "" @s`
+	keyctl restrict_keyring $chain_id asymmetric key_or_keyring:$root_id:chain
+
+	# Attempt to add each certificate in the chain, starting with the
+	# certificate closest to the root.
+	keyctl padd asymmetric "" $chain_id < intermediateA.cert
+	keyctl padd asymmetric "" $chain_id < intermediateB.cert
+	keyctl padd asymmetric "" $chain_id < end-entity.cert
+
+     If the final end-entity certificate is successfully added to the "chain"
+     keyring, we can be certain that it has a valid signing chain going back to
+     one of the root certificates.
+
+     A single keyring can be used to verify a chain of signatures by
+     restricting the keyring after linking the root certificate::
+
+	# Create a keyring for the certificate chain and add the root
+	chain2_id=`keyctl add keyring chain2 "" @s`
+	keyctl padd asymmetric "" $chain2_id < root1.cert
+
+	# Restrict the keyring that already has root1.cert linked.  The cert
+	# will remain linked by the keyring.
+	keyctl restrict_keyring $chain2_id asymmetric key_or_keyring:0:chain
+
+	# Attempt to add each certificate in the chain, starting with the
+	# certificate closest to the root.
+	keyctl padd asymmetric "" $chain2_id < intermediateA.cert
+	keyctl padd asymmetric "" $chain2_id < intermediateB.cert
+	keyctl padd asymmetric "" $chain2_id < end-entity.cert
+
+     If the final end-entity certificate is successfully added to the "chain2"
+     keyring, we can be certain that there is a valid signing chain going back
+     to the root certificate that was added before the keyring was restricted.
+
+
+In all of these cases, if the signing key is found the signature of the key to
+be linked will be verified using the signing key.  The requested key is added
+to the keyring only if the signature is successfully verified.  -ENOKEY is
+returned if the parent certificate could not be found, or -EKEYREJECTED is
+returned if the signature check fails or the key is blacklisted.  Other errors
+may be returned if the signature check could not be performed.
diff --git a/Documentation/crypto/async-tx-api.rst b/Documentation/crypto/async-tx-api.rst
new file mode 100644
index 000000000..bfc773991
--- /dev/null
+++ b/Documentation/crypto/async-tx-api.rst
@@ -0,0 +1,270 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=====================================
+Asynchronous Transfers/Transforms API
+=====================================
+
+.. Contents
+
+  1. INTRODUCTION
+
+  2 GENEALOGY
+
+  3 USAGE
+  3.1 General format of the API
+  3.2 Supported operations
+  3.3 Descriptor management
+  3.4 When does the operation execute?
+  3.5 When does the operation complete?
+  3.6 Constraints
+  3.7 Example
+
+  4 DMAENGINE DRIVER DEVELOPER NOTES
+  4.1 Conformance points
+  4.2 "My application needs exclusive control of hardware channels"
+
+  5 SOURCE
+
+1. Introduction
+===============
+
+The async_tx API provides methods for describing a chain of asynchronous
+bulk memory transfers/transforms with support for inter-transactional
+dependencies.  It is implemented as a dmaengine client that smooths over
+the details of different hardware offload engine implementations.  Code
+that is written to the API can optimize for asynchronous operation and
+the API will fit the chain of operations to the available offload
+resources.
+
+2.Genealogy
+===========
+
+The API was initially designed to offload the memory copy and
+xor-parity-calculations of the md-raid5 driver using the offload engines
+present in the Intel(R) Xscale series of I/O processors.  It also built
+on the 'dmaengine' layer developed for offloading memory copies in the
+network stack using Intel(R) I/OAT engines.  The following design
+features surfaced as a result:
+
+1. implicit synchronous path: users of the API do not need to know if
+   the platform they are running on has offload capabilities.  The
+   operation will be offloaded when an engine is available and carried out
+   in software otherwise.
+2. cross channel dependency chains: the API allows a chain of dependent
+   operations to be submitted, like xor->copy->xor in the raid5 case.  The
+   API automatically handles cases where the transition from one operation
+   to another implies a hardware channel switch.
+3. dmaengine extensions to support multiple clients and operation types
+   beyond 'memcpy'
+
+3. Usage
+========
+
+3.1 General format of the API
+-----------------------------
+
+::
+
+  struct dma_async_tx_descriptor *
+  async_<operation>(<op specific parameters>, struct async_submit ctl *submit)
+
+3.2 Supported operations
+------------------------
+
+========  ====================================================================
+memcpy    memory copy between a source and a destination buffer
+memset    fill a destination buffer with a byte value
+xor       xor a series of source buffers and write the result to a
+	  destination buffer
+xor_val   xor a series of source buffers and set a flag if the
+	  result is zero.  The implementation attempts to prevent
+	  writes to memory
+pq	  generate the p+q (raid6 syndrome) from a series of source buffers
+pq_val    validate that a p and or q buffer are in sync with a given series of
+	  sources
+datap	  (raid6_datap_recov) recover a raid6 data block and the p block
+	  from the given sources
+2data	  (raid6_2data_recov) recover 2 raid6 data blocks from the given
+	  sources
+========  ====================================================================
+
+3.3 Descriptor management
+-------------------------
+
+The return value is non-NULL and points to a 'descriptor' when the operation
+has been queued to execute asynchronously.  Descriptors are recycled
+resources, under control of the offload engine driver, to be reused as
+operations complete.  When an application needs to submit a chain of
+operations it must guarantee that the descriptor is not automatically recycled
+before the dependency is submitted.  This requires that all descriptors be
+acknowledged by the application before the offload engine driver is allowed to
+recycle (or free) the descriptor.  A descriptor can be acked by one of the
+following methods:
+
+1. setting the ASYNC_TX_ACK flag if no child operations are to be submitted
+2. submitting an unacknowledged descriptor as a dependency to another
+   async_tx call will implicitly set the acknowledged state.
+3. calling async_tx_ack() on the descriptor.
+
+3.4 When does the operation execute?
+------------------------------------
+
+Operations do not immediately issue after return from the
+async_<operation> call.  Offload engine drivers batch operations to
+improve performance by reducing the number of mmio cycles needed to
+manage the channel.  Once a driver-specific threshold is met the driver
+automatically issues pending operations.  An application can force this
+event by calling async_tx_issue_pending_all().  This operates on all
+channels since the application has no knowledge of channel to operation
+mapping.
+
+3.5 When does the operation complete?
+-------------------------------------
+
+There are two methods for an application to learn about the completion
+of an operation.
+
+1. Call dma_wait_for_async_tx().  This call causes the CPU to spin while
+   it polls for the completion of the operation.  It handles dependency
+   chains and issuing pending operations.
+2. Specify a completion callback.  The callback routine runs in tasklet
+   context if the offload engine driver supports interrupts, or it is
+   called in application context if the operation is carried out
+   synchronously in software.  The callback can be set in the call to
+   async_<operation>, or when the application needs to submit a chain of
+   unknown length it can use the async_trigger_callback() routine to set a
+   completion interrupt/callback at the end of the chain.
+
+3.6 Constraints
+---------------
+
+1. Calls to async_<operation> are not permitted in IRQ context.  Other
+   contexts are permitted provided constraint #2 is not violated.
+2. Completion callback routines cannot submit new operations.  This
+   results in recursion in the synchronous case and spin_locks being
+   acquired twice in the asynchronous case.
+
+3.7 Example
+-----------
+
+Perform a xor->copy->xor operation where each operation depends on the
+result from the previous operation::
+
+    void callback(void *param)
+    {
+	    struct completion *cmp = param;
+
+	    complete(cmp);
+    }
+
+    void run_xor_copy_xor(struct page **xor_srcs,
+			int xor_src_cnt,
+			struct page *xor_dest,
+			size_t xor_len,
+			struct page *copy_src,
+			struct page *copy_dest,
+			size_t copy_len)
+    {
+	    struct dma_async_tx_descriptor *tx;
+	    addr_conv_t addr_conv[xor_src_cnt];
+	    struct async_submit_ctl submit;
+	    addr_conv_t addr_conv[NDISKS];
+	    struct completion cmp;
+
+	    init_async_submit(&submit, ASYNC_TX_XOR_DROP_DST, NULL, NULL, NULL,
+			    addr_conv);
+	    tx = async_xor(xor_dest, xor_srcs, 0, xor_src_cnt, xor_len, &submit)
+
+	    submit->depend_tx = tx;
+	    tx = async_memcpy(copy_dest, copy_src, 0, 0, copy_len, &submit);
+
+	    init_completion(&cmp);
+	    init_async_submit(&submit, ASYNC_TX_XOR_DROP_DST | ASYNC_TX_ACK, tx,
+			    callback, &cmp, addr_conv);
+	    tx = async_xor(xor_dest, xor_srcs, 0, xor_src_cnt, xor_len, &submit);
+
+	    async_tx_issue_pending_all();
+
+	    wait_for_completion(&cmp);
+    }
+
+See include/linux/async_tx.h for more information on the flags.  See the
+ops_run_* and ops_complete_* routines in drivers/md/raid5.c for more
+implementation examples.
+
+4. Driver Development Notes
+===========================
+
+4.1 Conformance points
+----------------------
+
+There are a few conformance points required in dmaengine drivers to
+accommodate assumptions made by applications using the async_tx API:
+
+1. Completion callbacks are expected to happen in tasklet context
+2. dma_async_tx_descriptor fields are never manipulated in IRQ context
+3. Use async_tx_run_dependencies() in the descriptor clean up path to
+   handle submission of dependent operations
+
+4.2 "My application needs exclusive control of hardware channels"
+-----------------------------------------------------------------
+
+Primarily this requirement arises from cases where a DMA engine driver
+is being used to support device-to-memory operations.  A channel that is
+performing these operations cannot, for many platform specific reasons,
+be shared.  For these cases the dma_request_channel() interface is
+provided.
+
+The interface is::
+
+  struct dma_chan *dma_request_channel(dma_cap_mask_t mask,
+				       dma_filter_fn filter_fn,
+				       void *filter_param);
+
+Where dma_filter_fn is defined as::
+
+  typedef bool (*dma_filter_fn)(struct dma_chan *chan, void *filter_param);
+
+When the optional 'filter_fn' parameter is set to NULL
+dma_request_channel simply returns the first channel that satisfies the
+capability mask.  Otherwise, when the mask parameter is insufficient for
+specifying the necessary channel, the filter_fn routine can be used to
+disposition the available channels in the system. The filter_fn routine
+is called once for each free channel in the system.  Upon seeing a
+suitable channel filter_fn returns DMA_ACK which flags that channel to
+be the return value from dma_request_channel.  A channel allocated via
+this interface is exclusive to the caller, until dma_release_channel()
+is called.
+
+The DMA_PRIVATE capability flag is used to tag dma devices that should
+not be used by the general-purpose allocator.  It can be set at
+initialization time if it is known that a channel will always be
+private.  Alternatively, it is set when dma_request_channel() finds an
+unused "public" channel.
+
+A couple caveats to note when implementing a driver and consumer:
+
+1. Once a channel has been privately allocated it will no longer be
+   considered by the general-purpose allocator even after a call to
+   dma_release_channel().
+2. Since capabilities are specified at the device level a dma_device
+   with multiple channels will either have all channels public, or all
+   channels private.
+
+5. Source
+---------
+
+include/linux/dmaengine.h:
+    core header file for DMA drivers and api users
+drivers/dma/dmaengine.c:
+    offload engine channel management routines
+drivers/dma/:
+    location for offload engine drivers
+include/linux/async_tx.h:
+    core header file for the async_tx api
+crypto/async_tx/async_tx.c:
+    async_tx interface to dmaengine and common code
+crypto/async_tx/async_memcpy.c:
+    copy offload
+crypto/async_tx/async_xor.c:
+    xor and xor zero sum offload
diff --git a/Documentation/crypto/crypto_engine.rst b/Documentation/crypto/crypto_engine.rst
new file mode 100644
index 000000000..d562ea17d
--- /dev/null
+++ b/Documentation/crypto/crypto_engine.rst
@@ -0,0 +1,86 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Crypto Engine
+=============
+
+Overview
+--------
+The crypto engine (CE) API is a crypto queue manager.
+
+Requirement
+-----------
+You must put, at the start of your transform context your_tfm_ctx, the structure
+crypto_engine:
+
+::
+
+	struct your_tfm_ctx {
+		struct crypto_engine engine;
+		...
+	};
+
+The crypto engine only manages asynchronous requests in the form of
+crypto_async_request. It cannot know the underlying request type and thus only
+has access to the transform structure. It is not possible to access the context
+using container_of. In addition, the engine knows nothing about your
+structure "``struct your_tfm_ctx``". The engine assumes (requires) the placement
+of the known member ``struct crypto_engine`` at the beginning.
+
+Order of operations
+-------------------
+You are required to obtain a struct crypto_engine via ``crypto_engine_alloc_init()``.
+Start it via ``crypto_engine_start()``. When finished with your work, shut down the
+engine using ``crypto_engine_stop()`` and destroy the engine with
+``crypto_engine_exit()``.
+
+Before transferring any request, you have to fill the context enginectx by
+providing functions for the following:
+
+* ``prepare_crypt_hardware``: Called once before any prepare functions are
+  called.
+
+* ``unprepare_crypt_hardware``: Called once after all unprepare functions have
+  been called.
+
+* ``prepare_cipher_request``/``prepare_hash_request``: Called before each
+  corresponding request is performed. If some processing or other preparatory
+  work is required, do it here.
+
+* ``unprepare_cipher_request``/``unprepare_hash_request``: Called after each
+  request is handled. Clean up / undo what was done in the prepare function.
+
+* ``cipher_one_request``/``hash_one_request``: Handle the current request by
+  performing the operation.
+
+Note that these functions access the crypto_async_request structure
+associated with the received request. You are able to retrieve the original
+request by using:
+
+::
+
+	container_of(areq, struct yourrequesttype_request, base);
+
+When your driver receives a crypto_request, you must to transfer it to
+the crypto engine via one of:
+
+* crypto_transfer_aead_request_to_engine()
+
+* crypto_transfer_akcipher_request_to_engine()
+
+* crypto_transfer_hash_request_to_engine()
+
+* crypto_transfer_kpp_request_to_engine()
+
+* crypto_transfer_skcipher_request_to_engine()
+
+At the end of the request process, a call to one of the following functions is needed:
+
+* crypto_finalize_aead_request()
+
+* crypto_finalize_akcipher_request()
+
+* crypto_finalize_hash_request()
+
+* crypto_finalize_kpp_request()
+
+* crypto_finalize_skcipher_request()
diff --git a/Documentation/crypto/descore-readme.rst b/Documentation/crypto/descore-readme.rst
new file mode 100644
index 000000000..45bd9c8ba
--- /dev/null
+++ b/Documentation/crypto/descore-readme.rst
@@ -0,0 +1,414 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+===========================================
+Fast & Portable DES encryption & decryption
+===========================================
+
+.. note::
+
+   Below is the original README file from the descore.shar package,
+   converted to ReST format.
+
+------------------------------------------------------------------------------
+
+des - fast & portable DES encryption & decryption.
+
+Copyright |copy| 1992  Dana L. How
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Library General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+Author's address: how@isl.stanford.edu
+
+.. README,v 1.15 1992/05/20 00:25:32 how E
+
+==>> To compile after untarring/unsharring, just ``make`` <<==
+
+This package was designed with the following goals:
+
+1.	Highest possible encryption/decryption PERFORMANCE.
+2.	PORTABILITY to any byte-addressable host with a 32bit unsigned C type
+3.	Plug-compatible replacement for KERBEROS's low-level routines.
+
+This second release includes a number of performance enhancements for
+register-starved machines.  My discussions with Richard Outerbridge,
+71755.204@compuserve.com, sparked a number of these enhancements.
+
+To more rapidly understand the code in this package, inspect desSmallFips.i
+(created by typing ``make``) BEFORE you tackle desCode.h.  The latter is set
+up in a parameterized fashion so it can easily be modified by speed-daemon
+hackers in pursuit of that last microsecond.  You will find it more
+illuminating to inspect one specific implementation,
+and then move on to the common abstract skeleton with this one in mind.
+
+
+performance comparison to other available des code which i could
+compile on a SPARCStation 1 (cc -O4, gcc -O2):
+
+this code (byte-order independent):
+
+  - 30us per encryption (options: 64k tables, no IP/FP)
+  - 33us per encryption (options: 64k tables, FIPS standard bit ordering)
+  - 45us per encryption (options:  2k tables, no IP/FP)
+  - 48us per encryption (options:  2k tables, FIPS standard bit ordering)
+  - 275us to set a new key (uses 1k of key tables)
+
+	this has the quickest encryption/decryption routines i've seen.
+	since i was interested in fast des filters rather than crypt(3)
+	and password cracking, i haven't really bothered yet to speed up
+	the key setting routine. also, i have no interest in re-implementing
+	all the other junk in the mit kerberos des library, so i've just
+	provided my routines with little stub interfaces so they can be
+	used as drop-in replacements with mit's code or any of the mit-
+	compatible packages below. (note that the first two timings above
+	are highly variable because of cache effects).
+
+kerberos des replacement from australia (version 1.95):
+
+  - 53us per encryption (uses 2k of tables)
+  - 96us to set a new key (uses 2.25k of key tables)
+
+	so despite the author's inclusion of some of the performance
+	improvements i had suggested to him, this package's
+	encryption/decryption is still slower on the sparc and 68000.
+	more specifically, 19-40% slower on the 68020 and 11-35% slower
+	on the sparc,  depending on the compiler;
+	in full gory detail (ALT_ECB is a libdes variant):
+
+	===============	==============	===============	=================
+	compiler   	machine		desCore	libdes	ALT_ECB	slower by
+	===============	==============	===============	=================
+	gcc 2.1 -O2	Sun 3/110	304  uS	369.5uS	461.8uS	 22%
+	cc      -O1	Sun 3/110	336  uS	436.6uS	399.3uS	 19%
+	cc      -O2	Sun 3/110	360  uS	532.4uS	505.1uS	 40%
+	cc      -O4	Sun 3/110	365  uS	532.3uS	505.3uS	 38%
+	gcc 2.1 -O2	Sun 4/50	 48  uS	 53.4uS	 57.5uS	 11%
+	cc      -O2	Sun 4/50	 48  uS	 64.6uS	 64.7uS	 35%
+	cc      -O4	Sun 4/50	 48  uS	 64.7uS	 64.9uS	 35%
+	===============	==============	===============	=================
+
+	(my time measurements are not as accurate as his).
+
+   the comments in my first release of desCore on version 1.92:
+
+   - 68us per encryption (uses 2k of tables)
+   - 96us to set a new key (uses 2.25k of key tables)
+
+	this is a very nice package which implements the most important
+	of the optimizations which i did in my encryption routines.
+	it's a bit weak on common low-level optimizations which is why
+	it's 39%-106% slower.  because he was interested in fast crypt(3) and
+	password-cracking applications,  he also used the same ideas to
+	speed up the key-setting routines with impressive results.
+	(at some point i may do the same in my package).  he also implements
+	the rest of the mit des library.
+
+	(code from eay@psych.psy.uq.oz.au via comp.sources.misc)
+
+fast crypt(3) package from denmark:
+
+	the des routine here is buried inside a loop to do the
+	crypt function and i didn't feel like ripping it out and measuring
+	performance. his code takes 26 sparc instructions to compute one
+	des iteration; above, Quick (64k) takes 21 and Small (2k) takes 37.
+	he claims to use 280k of tables but the iteration calculation seems
+	to use only 128k.  his tables and code are machine independent.
+
+	(code from glad@daimi.aau.dk via alt.sources or comp.sources.misc)
+
+swedish reimplementation of Kerberos des library
+
+  - 108us per encryption (uses 34k worth of tables)
+  - 134us to set a new key (uses 32k of key tables to get this speed!)
+
+	the tables used seem to be machine-independent;
+	he seems to have included a lot of special case code
+	so that, e.g., ``long`` loads can be used instead of 4 ``char`` loads
+	when the machine's architecture allows it.
+
+	(code obtained from chalmers.se:pub/des)
+
+crack 3.3c package from england:
+
+	as in crypt above, the des routine is buried in a loop. it's
+	also very modified for crypt.  his iteration code uses 16k
+	of tables and appears to be slow.
+
+	(code obtained from aem@aber.ac.uk via alt.sources or comp.sources.misc)
+
+``highly optimized`` and tweaked Kerberos/Athena code (byte-order dependent):
+
+  - 165us per encryption (uses 6k worth of tables)
+  - 478us to set a new key (uses <1k of key tables)
+
+	so despite the comments in this code, it was possible to get
+	faster code AND smaller tables, as well as making the tables
+	machine-independent.
+	(code obtained from prep.ai.mit.edu)
+
+UC Berkeley code (depends on machine-endedness):
+  -  226us per encryption
+  - 10848us to set a new key
+
+	table sizes are unclear, but they don't look very small
+	(code obtained from wuarchive.wustl.edu)
+
+
+motivation and history
+======================
+
+a while ago i wanted some des routines and the routines documented on sun's
+man pages either didn't exist or dumped core.  i had heard of kerberos,
+and knew that it used des,  so i figured i'd use its routines.  but once
+i got it and looked at the code,  it really set off a lot of pet peeves -
+it was too convoluted, the code had been written without taking
+advantage of the regular structure of operations such as IP, E, and FP
+(i.e. the author didn't sit down and think before coding),
+it was excessively slow,  the author had attempted to clarify the code
+by adding MORE statements to make the data movement more ``consistent``
+instead of simplifying his implementation and cutting down on all data
+movement (in particular, his use of L1, R1, L2, R2), and it was full of
+idiotic ``tweaks`` for particular machines which failed to deliver significant
+speedups but which did obfuscate everything.  so i took the test data
+from his verification program and rewrote everything else.
+
+a while later i ran across the great crypt(3) package mentioned above.
+the fact that this guy was computing 2 sboxes per table lookup rather
+than one (and using a MUCH larger table in the process) emboldened me to
+do the same - it was a trivial change from which i had been scared away
+by the larger table size.  in his case he didn't realize you don't need to keep
+the working data in TWO forms, one for easy use of half the sboxes in
+indexing, the other for easy use of the other half; instead you can keep
+it in the form for the first half and use a simple rotate to get the other
+half.  this means i have (almost) half the data manipulation and half
+the table size.  in fairness though he might be encoding something particular
+to crypt(3) in his tables - i didn't check.
+
+i'm glad that i implemented it the way i did, because this C version is
+portable (the ifdef's are performance enhancements) and it is faster
+than versions hand-written in assembly for the sparc!
+
+
+porting notes
+=============
+
+one thing i did not want to do was write an enormous mess
+which depended on endedness and other machine quirks,
+and which necessarily produced different code and different lookup tables
+for different machines.  see the kerberos code for an example
+of what i didn't want to do; all their endedness-specific ``optimizations``
+obfuscate the code and in the end were slower than a simpler machine
+independent approach.  however, there are always some portability
+considerations of some kind, and i have included some options
+for varying numbers of register variables.
+perhaps some will still regard the result as a mess!
+
+1) i assume everything is byte addressable, although i don't actually
+   depend on the byte order, and that bytes are 8 bits.
+   i assume word pointers can be freely cast to and from char pointers.
+   note that 99% of C programs make these assumptions.
+   i always use unsigned char's if the high bit could be set.
+2) the typedef ``word`` means a 32 bit unsigned integral type.
+   if ``unsigned long`` is not 32 bits, change the typedef in desCore.h.
+   i assume sizeof(word) == 4 EVERYWHERE.
+
+the (worst-case) cost of my NOT doing endedness-specific optimizations
+in the data loading and storing code surrounding the key iterations
+is less than 12%.  also, there is the added benefit that
+the input and output work areas do not need to be word-aligned.
+
+
+OPTIONAL performance optimizations
+==================================
+
+1) you should define one of ``i386,`` ``vax,`` ``mc68000,`` or ``sparc,``
+   whichever one is closest to the capabilities of your machine.
+   see the start of desCode.h to see exactly what this selection implies.
+   note that if you select the wrong one, the des code will still work;
+   these are just performance tweaks.
+2) for those with functional ``asm`` keywords: you should change the
+   ROR and ROL macros to use machine rotate instructions if you have them.
+   this will save 2 instructions and a temporary per use,
+   or about 32 to 40 instructions per en/decryption.
+
+   note that gcc is smart enough to translate the ROL/R macros into
+   machine rotates!
+
+these optimizations are all rather persnickety, yet with them you should
+be able to get performance equal to assembly-coding, except that:
+
+1) with the lack of a bit rotate operator in C, rotates have to be synthesized
+   from shifts.  so access to ``asm`` will speed things up if your machine
+   has rotates, as explained above in (3) (not necessary if you use gcc).
+2) if your machine has less than 12 32-bit registers i doubt your compiler will
+   generate good code.
+
+   ``i386`` tries to configure the code for a 386 by only declaring 3 registers
+   (it appears that gcc can use ebx, esi and edi to hold register variables).
+   however, if you like assembly coding, the 386 does have 7 32-bit registers,
+   and if you use ALL of them, use ``scaled by 8`` address modes with displacement
+   and other tricks, you can get reasonable routines for DesQuickCore... with
+   about 250 instructions apiece.  For DesSmall... it will help to rearrange
+   des_keymap, i.e., now the sbox # is the high part of the index and
+   the 6 bits of data is the low part; it helps to exchange these.
+
+   since i have no way to conveniently test it i have not provided my
+   shoehorned 386 version.  note that with this release of desCore, gcc is able
+   to put everything in registers(!), and generate about 370 instructions apiece
+   for the DesQuickCore... routines!
+
+coding notes
+============
+
+the en/decryption routines each use 6 necessary register variables,
+with 4 being actively used at once during the inner iterations.
+if you don't have 4 register variables get a new machine.
+up to 8 more registers are used to hold constants in some configurations.
+
+i assume that the use of a constant is more expensive than using a register:
+
+a) additionally, i have tried to put the larger constants in registers.
+   registering priority was by the following:
+
+	- anything more than 12 bits (bad for RISC and CISC)
+	- greater than 127 in value (can't use movq or byte immediate on CISC)
+	- 9-127 (may not be able to use CISC shift immediate or add/sub quick),
+	- 1-8 were never registered, being the cheapest constants.
+
+b) the compiler may be too stupid to realize table and table+256 should
+   be assigned to different constant registers and instead repetitively
+   do the arithmetic, so i assign these to explicit ``m`` register variables
+   when possible and helpful.
+
+i assume that indexing is cheaper or equivalent to auto increment/decrement,
+where the index is 7 bits unsigned or smaller.
+this assumption is reversed for 68k and vax.
+
+i assume that addresses can be cheaply formed from two registers,
+or from a register and a small constant.
+for the 68000, the ``two registers and small offset`` form is used sparingly.
+all index scaling is done explicitly - no hidden shifts by log2(sizeof).
+
+the code is written so that even a dumb compiler
+should never need more than one hidden temporary,
+increasing the chance that everything will fit in the registers.
+KEEP THIS MORE SUBTLE POINT IN MIND IF YOU REWRITE ANYTHING.
+
+(actually, there are some code fragments now which do require two temps,
+but fixing it would either break the structure of the macros or
+require declaring another temporary).
+
+
+special efficient data format
+==============================
+
+bits are manipulated in this arrangement most of the time (S7 S5 S3 S1)::
+
+	003130292827xxxx242322212019xxxx161514131211xxxx080706050403xxxx
+
+(the x bits are still there, i'm just emphasizing where the S boxes are).
+bits are rotated left 4 when computing S6 S4 S2 S0::
+
+	282726252423xxxx201918171615xxxx121110090807xxxx040302010031xxxx
+
+the rightmost two bits are usually cleared so the lower byte can be used
+as an index into an sbox mapping table. the next two x'd bits are set
+to various values to access different parts of the tables.
+
+
+how to use the routines
+
+datatypes:
+	pointer to 8 byte area of type DesData
+	used to hold keys and input/output blocks to des.
+
+	pointer to 128 byte area of type DesKeys
+	used to hold full 768-bit key.
+	must be long-aligned.
+
+DesQuickInit()
+	call this before using any other routine with ``Quick`` in its name.
+	it generates the special 64k table these routines need.
+DesQuickDone()
+	frees this table
+
+DesMethod(m, k)
+	m points to a 128byte block, k points to an 8 byte des key
+	which must have odd parity (or -1 is returned) and which must
+	not be a (semi-)weak key (or -2 is returned).
+	normally DesMethod() returns 0.
+
+	m is filled in from k so that when one of the routines below
+	is called with m, the routine will act like standard des
+	en/decryption with the key k. if you use DesMethod,
+	you supply a standard 56bit key; however, if you fill in
+	m yourself, you will get a 768bit key - but then it won't
+	be standard.  it's 768bits not 1024 because the least significant
+	two bits of each byte are not used.  note that these two bits
+	will be set to magic constants which speed up the encryption/decryption
+	on some machines.  and yes, each byte controls
+	a specific sbox during a specific iteration.
+
+	you really shouldn't use the 768bit format directly;  i should
+	provide a routine that converts 128 6-bit bytes (specified in
+	S-box mapping order or something) into the right format for you.
+	this would entail some byte concatenation and rotation.
+
+Des{Small|Quick}{Fips|Core}{Encrypt|Decrypt}(d, m, s)
+	performs des on the 8 bytes at s into the 8 bytes at
+	``d. (d,s: char *)``.
+
+	uses m as a 768bit key as explained above.
+
+	the Encrypt|Decrypt choice is obvious.
+
+	Fips|Core determines whether a completely standard FIPS initial
+	and final permutation is done; if not, then the data is loaded
+	and stored in a nonstandard bit order (FIPS w/o IP/FP).
+
+	Fips slows down Quick by 10%, Small by 9%.
+
+	Small|Quick determines whether you use the normal routine
+	or the crazy quick one which gobbles up 64k more of memory.
+	Small is 50% slower then Quick, but Quick needs 32 times as much
+	memory.  Quick is included for programs that do nothing but DES,
+	e.g., encryption filters, etc.
+
+
+Getting it to compile on your machine
+=====================================
+
+there are no machine-dependencies in the code (see porting),
+except perhaps the ``now()`` macro in desTest.c.
+ALL generated tables are machine independent.
+you should edit the Makefile with the appropriate optimization flags
+for your compiler (MAX optimization).
+
+
+Speeding up kerberos (and/or its des library)
+=============================================
+
+note that i have included a kerberos-compatible interface in desUtil.c
+through the functions des_key_sched() and des_ecb_encrypt().
+to use these with kerberos or kerberos-compatible code put desCore.a
+ahead of the kerberos-compatible library on your linker's command line.
+you should not need to #include desCore.h;  just include the header
+file provided with the kerberos library.
+
+Other uses
+==========
+
+the macros in desCode.h would be very useful for putting inline des
+functions in more complicated encryption routines.
diff --git a/Documentation/crypto/devel-algos.rst b/Documentation/crypto/devel-algos.rst
new file mode 100644
index 000000000..f225a953a
--- /dev/null
+++ b/Documentation/crypto/devel-algos.rst
@@ -0,0 +1,240 @@
+Developing Cipher Algorithms
+============================
+
+Registering And Unregistering Transformation
+--------------------------------------------
+
+There are three distinct types of registration functions in the Crypto
+API. One is used to register a generic cryptographic transformation,
+while the other two are specific to HASH transformations and
+COMPRESSion. We will discuss the latter two in a separate chapter, here
+we will only look at the generic ones.
+
+Before discussing the register functions, the data structure to be
+filled with each, struct crypto_alg, must be considered -- see below
+for a description of this data structure.
+
+The generic registration functions can be found in
+include/linux/crypto.h and their definition can be seen below. The
+former function registers a single transformation, while the latter
+works on an array of transformation descriptions. The latter is useful
+when registering transformations in bulk, for example when a driver
+implements multiple transformations.
+
+::
+
+       int crypto_register_alg(struct crypto_alg *alg);
+       int crypto_register_algs(struct crypto_alg *algs, int count);
+
+
+The counterparts to those functions are listed below.
+
+::
+
+       void crypto_unregister_alg(struct crypto_alg *alg);
+       void crypto_unregister_algs(struct crypto_alg *algs, int count);
+
+
+The registration functions return 0 on success, or a negative errno
+value on failure.  crypto_register_algs() succeeds only if it
+successfully registered all the given algorithms; if it fails partway
+through, then any changes are rolled back.
+
+The unregistration functions always succeed, so they don't have a
+return value.  Don't try to unregister algorithms that aren't
+currently registered.
+
+Single-Block Symmetric Ciphers [CIPHER]
+---------------------------------------
+
+Example of transformations: aes, serpent, ...
+
+This section describes the simplest of all transformation
+implementations, that being the CIPHER type used for symmetric ciphers.
+The CIPHER type is used for transformations which operate on exactly one
+block at a time and there are no dependencies between blocks at all.
+
+Registration specifics
+~~~~~~~~~~~~~~~~~~~~~~
+
+The registration of [CIPHER] algorithm is specific in that struct
+crypto_alg field .cra_type is empty. The .cra_u.cipher has to be
+filled in with proper callbacks to implement this transformation.
+
+See struct cipher_alg below.
+
+Cipher Definition With struct cipher_alg
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Struct cipher_alg defines a single block cipher.
+
+Here are schematics of how these functions are called when operated from
+other part of the kernel. Note that the .cia_setkey() call might happen
+before or after any of these schematics happen, but must not happen
+during any of these are in-flight.
+
+::
+
+             KEY ---.    PLAINTEXT ---.
+                    v                 v
+              .cia_setkey() -> .cia_encrypt()
+                                      |
+                                      '-----> CIPHERTEXT
+
+
+Please note that a pattern where .cia_setkey() is called multiple times
+is also valid:
+
+::
+
+
+      KEY1 --.    PLAINTEXT1 --.         KEY2 --.    PLAINTEXT2 --.
+             v                 v                v                 v
+       .cia_setkey() -> .cia_encrypt() -> .cia_setkey() -> .cia_encrypt()
+                               |                                  |
+                               '---> CIPHERTEXT1                  '---> CIPHERTEXT2
+
+
+Multi-Block Ciphers
+-------------------
+
+Example of transformations: cbc(aes), chacha20, ...
+
+This section describes the multi-block cipher transformation
+implementations. The multi-block ciphers are used for transformations
+which operate on scatterlists of data supplied to the transformation
+functions. They output the result into a scatterlist of data as well.
+
+Registration Specifics
+~~~~~~~~~~~~~~~~~~~~~~
+
+The registration of multi-block cipher algorithms is one of the most
+standard procedures throughout the crypto API.
+
+Note, if a cipher implementation requires a proper alignment of data,
+the caller should use the functions of crypto_skcipher_alignmask() to
+identify a memory alignment mask. The kernel crypto API is able to
+process requests that are unaligned. This implies, however, additional
+overhead as the kernel crypto API needs to perform the realignment of
+the data which may imply moving of data.
+
+Cipher Definition With struct skcipher_alg
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Struct skcipher_alg defines a multi-block cipher, or more generally, a
+length-preserving symmetric cipher algorithm.
+
+Scatterlist handling
+~~~~~~~~~~~~~~~~~~~~
+
+Some drivers will want to use the Generic ScatterWalk in case the
+hardware needs to be fed separate chunks of the scatterlist which
+contains the plaintext and will contain the ciphertext. Please refer
+to the ScatterWalk interface offered by the Linux kernel scatter /
+gather list implementation.
+
+Hashing [HASH]
+--------------
+
+Example of transformations: crc32, md5, sha1, sha256,...
+
+Registering And Unregistering The Transformation
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+There are multiple ways to register a HASH transformation, depending on
+whether the transformation is synchronous [SHASH] or asynchronous
+[AHASH] and the amount of HASH transformations we are registering. You
+can find the prototypes defined in include/crypto/internal/hash.h:
+
+::
+
+       int crypto_register_ahash(struct ahash_alg *alg);
+
+       int crypto_register_shash(struct shash_alg *alg);
+       int crypto_register_shashes(struct shash_alg *algs, int count);
+
+
+The respective counterparts for unregistering the HASH transformation
+are as follows:
+
+::
+
+       void crypto_unregister_ahash(struct ahash_alg *alg);
+
+       void crypto_unregister_shash(struct shash_alg *alg);
+       void crypto_unregister_shashes(struct shash_alg *algs, int count);
+
+
+Cipher Definition With struct shash_alg and ahash_alg
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Here are schematics of how these functions are called when operated from
+other part of the kernel. Note that the .setkey() call might happen
+before or after any of these schematics happen, but must not happen
+during any of these are in-flight. Please note that calling .init()
+followed immediately by .finish() is also a perfectly valid
+transformation.
+
+::
+
+       I)   DATA -----------.
+                            v
+             .init() -> .update() -> .final()      ! .update() might not be called
+                         ^    |         |            at all in this scenario.
+                         '----'         '---> HASH
+
+       II)  DATA -----------.-----------.
+                            v           v
+             .init() -> .update() -> .finup()      ! .update() may not be called
+                         ^    |         |            at all in this scenario.
+                         '----'         '---> HASH
+
+       III) DATA -----------.
+                            v
+                        .digest()                  ! The entire process is handled
+                            |                        by the .digest() call.
+                            '---------------> HASH
+
+
+Here is a schematic of how the .export()/.import() functions are called
+when used from another part of the kernel.
+
+::
+
+       KEY--.                 DATA--.
+            v                       v                  ! .update() may not be called
+        .setkey() -> .init() -> .update() -> .export()   at all in this scenario.
+                                 ^     |         |
+                                 '-----'         '--> PARTIAL_HASH
+
+       ----------- other transformations happen here -----------
+
+       PARTIAL_HASH--.   DATA1--.
+                     v          v
+                 .import -> .update() -> .final()     ! .update() may not be called
+                             ^    |         |           at all in this scenario.
+                             '----'         '--> HASH1
+
+       PARTIAL_HASH--.   DATA2-.
+                     v         v
+                 .import -> .finup()
+                               |
+                               '---------------> HASH2
+
+Note that it is perfectly legal to "abandon" a request object:
+- call .init() and then (as many times) .update()
+- _not_ call any of .final(), .finup() or .export() at any point in future
+
+In other words implementations should mind the resource allocation and clean-up.
+No resources related to request objects should remain allocated after a call
+to .init() or .update(), since there might be no chance to free them.
+
+
+Specifics Of Asynchronous HASH Transformation
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Some of the drivers will want to use the Generic ScatterWalk in case the
+implementation needs to be fed separate chunks of the scatterlist which
+contains the input data. The buffer containing the resulting hash will
+always be properly aligned to .cra_alignmask so there is no need to
+worry about this.
diff --git a/Documentation/crypto/index.rst b/Documentation/crypto/index.rst
new file mode 100644
index 000000000..21338fa92
--- /dev/null
+++ b/Documentation/crypto/index.rst
@@ -0,0 +1,30 @@
+=======================
+Linux Kernel Crypto API
+=======================
+
+:Author: Stephan Mueller
+:Author: Marek Vasut
+
+This documentation outlines the Linux kernel crypto API with its
+concepts, details about developing cipher implementations, employment of the API
+for cryptographic use cases, as well as programming examples.
+
+.. class:: toc-title
+
+	   Table of contents
+
+.. toctree::
+   :maxdepth: 2
+
+   intro
+   api-intro
+   architecture
+
+   async-tx-api
+   asymmetric-keys
+   devel-algos
+   userspace-if
+   crypto_engine
+   api
+   api-samples
+   descore-readme
diff --git a/Documentation/crypto/intro.rst b/Documentation/crypto/intro.rst
new file mode 100644
index 000000000..9aa89ebbf
--- /dev/null
+++ b/Documentation/crypto/intro.rst
@@ -0,0 +1,74 @@
+Kernel Crypto API Interface Specification
+=========================================
+
+Introduction
+------------
+
+The kernel crypto API offers a rich set of cryptographic ciphers as well
+as other data transformation mechanisms and methods to invoke these.
+This document contains a description of the API and provides example
+code.
+
+To understand and properly use the kernel crypto API a brief explanation
+of its structure is given. Based on the architecture, the API can be
+separated into different components. Following the architecture
+specification, hints to developers of ciphers are provided. Pointers to
+the API function call documentation are given at the end.
+
+The kernel crypto API refers to all algorithms as "transformations".
+Therefore, a cipher handle variable usually has the name "tfm". Besides
+cryptographic operations, the kernel crypto API also knows compression
+transformations and handles them the same way as ciphers.
+
+The kernel crypto API serves the following entity types:
+
+-  consumers requesting cryptographic services
+
+-  data transformation implementations (typically ciphers) that can be
+   called by consumers using the kernel crypto API
+
+This specification is intended for consumers of the kernel crypto API as
+well as for developers implementing ciphers. This API specification,
+however, does not discuss all API calls available to data transformation
+implementations (i.e. implementations of ciphers and other
+transformations (such as CRC or even compression algorithms) that can
+register with the kernel crypto API).
+
+Note: The terms "transformation" and cipher algorithm are used
+interchangeably.
+
+Terminology
+-----------
+
+The transformation implementation is an actual code or interface to
+hardware which implements a certain transformation with precisely
+defined behavior.
+
+The transformation object (TFM) is an instance of a transformation
+implementation. There can be multiple transformation objects associated
+with a single transformation implementation. Each of those
+transformation objects is held by a crypto API consumer or another
+transformation. Transformation object is allocated when a crypto API
+consumer requests a transformation implementation. The consumer is then
+provided with a structure, which contains a transformation object (TFM).
+
+The structure that contains transformation objects may also be referred
+to as a "cipher handle". Such a cipher handle is always subject to the
+following phases that are reflected in the API calls applicable to such
+a cipher handle:
+
+1. Initialization of a cipher handle.
+
+2. Execution of all intended cipher operations applicable for the handle
+   where the cipher handle must be furnished to every API call.
+
+3. Destruction of a cipher handle.
+
+When using the initialization API calls, a cipher handle is created and
+returned to the consumer. Therefore, please refer to all initialization
+API calls that refer to the data structure type a consumer is expected
+to receive and subsequently to use. The initialization API calls have
+all the same naming conventions of crypto_alloc\*.
+
+The transformation context is private data associated with the
+transformation object.
diff --git a/Documentation/crypto/userspace-if.rst b/Documentation/crypto/userspace-if.rst
new file mode 100644
index 000000000..b45dabbf6
--- /dev/null
+++ b/Documentation/crypto/userspace-if.rst
@@ -0,0 +1,401 @@
+User Space Interface
+====================
+
+Introduction
+------------
+
+The concepts of the kernel crypto API visible to kernel space is fully
+applicable to the user space interface as well. Therefore, the kernel
+crypto API high level discussion for the in-kernel use cases applies
+here as well.
+
+The major difference, however, is that user space can only act as a
+consumer and never as a provider of a transformation or cipher
+algorithm.
+
+The following covers the user space interface exported by the kernel
+crypto API. A working example of this description is libkcapi that can
+be obtained from [1]. That library can be used by user space
+applications that require cryptographic services from the kernel.
+
+Some details of the in-kernel kernel crypto API aspects do not apply to
+user space, however. This includes the difference between synchronous
+and asynchronous invocations. The user space API call is fully
+synchronous.
+
+[1] https://www.chronox.de/libkcapi.html
+
+User Space API General Remarks
+------------------------------
+
+The kernel crypto API is accessible from user space. Currently, the
+following ciphers are accessible:
+
+-  Message digest including keyed message digest (HMAC, CMAC)
+
+-  Symmetric ciphers
+
+-  AEAD ciphers
+
+-  Random Number Generators
+
+The interface is provided via socket type using the type AF_ALG. In
+addition, the setsockopt option type is SOL_ALG. In case the user space
+header files do not export these flags yet, use the following macros:
+
+::
+
+    #ifndef AF_ALG
+    #define AF_ALG 38
+    #endif
+    #ifndef SOL_ALG
+    #define SOL_ALG 279
+    #endif
+
+
+A cipher is accessed with the same name as done for the in-kernel API
+calls. This includes the generic vs. unique naming schema for ciphers as
+well as the enforcement of priorities for generic names.
+
+To interact with the kernel crypto API, a socket must be created by the
+user space application. User space invokes the cipher operation with the
+send()/write() system call family. The result of the cipher operation is
+obtained with the read()/recv() system call family.
+
+The following API calls assume that the socket descriptor is already
+opened by the user space application and discusses only the kernel
+crypto API specific invocations.
+
+To initialize the socket interface, the following sequence has to be
+performed by the consumer:
+
+1. Create a socket of type AF_ALG with the struct sockaddr_alg
+   parameter specified below for the different cipher types.
+
+2. Invoke bind with the socket descriptor
+
+3. Invoke accept with the socket descriptor. The accept system call
+   returns a new file descriptor that is to be used to interact with the
+   particular cipher instance. When invoking send/write or recv/read
+   system calls to send data to the kernel or obtain data from the
+   kernel, the file descriptor returned by accept must be used.
+
+In-place Cipher operation
+-------------------------
+
+Just like the in-kernel operation of the kernel crypto API, the user
+space interface allows the cipher operation in-place. That means that
+the input buffer used for the send/write system call and the output
+buffer used by the read/recv system call may be one and the same. This
+is of particular interest for symmetric cipher operations where a
+copying of the output data to its final destination can be avoided.
+
+If a consumer on the other hand wants to maintain the plaintext and the
+ciphertext in different memory locations, all a consumer needs to do is
+to provide different memory pointers for the encryption and decryption
+operation.
+
+Message Digest API
+------------------
+
+The message digest type to be used for the cipher operation is selected
+when invoking the bind syscall. bind requires the caller to provide a
+filled struct sockaddr data structure. This data structure must be
+filled as follows:
+
+::
+
+    struct sockaddr_alg sa = {
+        .salg_family = AF_ALG,
+        .salg_type = "hash", /* this selects the hash logic in the kernel */
+        .salg_name = "sha1" /* this is the cipher name */
+    };
+
+
+The salg_type value "hash" applies to message digests and keyed message
+digests. Though, a keyed message digest is referenced by the appropriate
+salg_name. Please see below for the setsockopt interface that explains
+how the key can be set for a keyed message digest.
+
+Using the send() system call, the application provides the data that
+should be processed with the message digest. The send system call allows
+the following flags to be specified:
+
+-  MSG_MORE: If this flag is set, the send system call acts like a
+   message digest update function where the final hash is not yet
+   calculated. If the flag is not set, the send system call calculates
+   the final message digest immediately.
+
+With the recv() system call, the application can read the message digest
+from the kernel crypto API. If the buffer is too small for the message
+digest, the flag MSG_TRUNC is set by the kernel.
+
+In order to set a message digest key, the calling application must use
+the setsockopt() option of ALG_SET_KEY. If the key is not set the HMAC
+operation is performed without the initial HMAC state change caused by
+the key.
+
+Symmetric Cipher API
+--------------------
+
+The operation is very similar to the message digest discussion. During
+initialization, the struct sockaddr data structure must be filled as
+follows:
+
+::
+
+    struct sockaddr_alg sa = {
+        .salg_family = AF_ALG,
+        .salg_type = "skcipher", /* this selects the symmetric cipher */
+        .salg_name = "cbc(aes)" /* this is the cipher name */
+    };
+
+
+Before data can be sent to the kernel using the write/send system call
+family, the consumer must set the key. The key setting is described with
+the setsockopt invocation below.
+
+Using the sendmsg() system call, the application provides the data that
+should be processed for encryption or decryption. In addition, the IV is
+specified with the data structure provided by the sendmsg() system call.
+
+The sendmsg system call parameter of struct msghdr is embedded into the
+struct cmsghdr data structure. See recv(2) and cmsg(3) for more
+information on how the cmsghdr data structure is used together with the
+send/recv system call family. That cmsghdr data structure holds the
+following information specified with a separate header instances:
+
+-  specification of the cipher operation type with one of these flags:
+
+   -  ALG_OP_ENCRYPT - encryption of data
+
+   -  ALG_OP_DECRYPT - decryption of data
+
+-  specification of the IV information marked with the flag ALG_SET_IV
+
+The send system call family allows the following flag to be specified:
+
+-  MSG_MORE: If this flag is set, the send system call acts like a
+   cipher update function where more input data is expected with a
+   subsequent invocation of the send system call.
+
+Note: The kernel reports -EINVAL for any unexpected data. The caller
+must make sure that all data matches the constraints given in
+/proc/crypto for the selected cipher.
+
+With the recv() system call, the application can read the result of the
+cipher operation from the kernel crypto API. The output buffer must be
+at least as large as to hold all blocks of the encrypted or decrypted
+data. If the output data size is smaller, only as many blocks are
+returned that fit into that output buffer size.
+
+AEAD Cipher API
+---------------
+
+The operation is very similar to the symmetric cipher discussion. During
+initialization, the struct sockaddr data structure must be filled as
+follows:
+
+::
+
+    struct sockaddr_alg sa = {
+        .salg_family = AF_ALG,
+        .salg_type = "aead", /* this selects the symmetric cipher */
+        .salg_name = "gcm(aes)" /* this is the cipher name */
+    };
+
+
+Before data can be sent to the kernel using the write/send system call
+family, the consumer must set the key. The key setting is described with
+the setsockopt invocation below.
+
+In addition, before data can be sent to the kernel using the write/send
+system call family, the consumer must set the authentication tag size.
+To set the authentication tag size, the caller must use the setsockopt
+invocation described below.
+
+Using the sendmsg() system call, the application provides the data that
+should be processed for encryption or decryption. In addition, the IV is
+specified with the data structure provided by the sendmsg() system call.
+
+The sendmsg system call parameter of struct msghdr is embedded into the
+struct cmsghdr data structure. See recv(2) and cmsg(3) for more
+information on how the cmsghdr data structure is used together with the
+send/recv system call family. That cmsghdr data structure holds the
+following information specified with a separate header instances:
+
+-  specification of the cipher operation type with one of these flags:
+
+   -  ALG_OP_ENCRYPT - encryption of data
+
+   -  ALG_OP_DECRYPT - decryption of data
+
+-  specification of the IV information marked with the flag ALG_SET_IV
+
+-  specification of the associated authentication data (AAD) with the
+   flag ALG_SET_AEAD_ASSOCLEN. The AAD is sent to the kernel together
+   with the plaintext / ciphertext. See below for the memory structure.
+
+The send system call family allows the following flag to be specified:
+
+-  MSG_MORE: If this flag is set, the send system call acts like a
+   cipher update function where more input data is expected with a
+   subsequent invocation of the send system call.
+
+Note: The kernel reports -EINVAL for any unexpected data. The caller
+must make sure that all data matches the constraints given in
+/proc/crypto for the selected cipher.
+
+With the recv() system call, the application can read the result of the
+cipher operation from the kernel crypto API. The output buffer must be
+at least as large as defined with the memory structure below. If the
+output data size is smaller, the cipher operation is not performed.
+
+The authenticated decryption operation may indicate an integrity error.
+Such breach in integrity is marked with the -EBADMSG error code.
+
+AEAD Memory Structure
+~~~~~~~~~~~~~~~~~~~~~
+
+The AEAD cipher operates with the following information that is
+communicated between user and kernel space as one data stream:
+
+-  plaintext or ciphertext
+
+-  associated authentication data (AAD)
+
+-  authentication tag
+
+The sizes of the AAD and the authentication tag are provided with the
+sendmsg and setsockopt calls (see there). As the kernel knows the size
+of the entire data stream, the kernel is now able to calculate the right
+offsets of the data components in the data stream.
+
+The user space caller must arrange the aforementioned information in the
+following order:
+
+-  AEAD encryption input: AAD \|\| plaintext
+
+-  AEAD decryption input: AAD \|\| ciphertext \|\| authentication tag
+
+The output buffer the user space caller provides must be at least as
+large to hold the following data:
+
+-  AEAD encryption output: ciphertext \|\| authentication tag
+
+-  AEAD decryption output: plaintext
+
+Random Number Generator API
+---------------------------
+
+Again, the operation is very similar to the other APIs. During
+initialization, the struct sockaddr data structure must be filled as
+follows:
+
+::
+
+    struct sockaddr_alg sa = {
+        .salg_family = AF_ALG,
+        .salg_type = "rng", /* this selects the random number generator */
+        .salg_name = "drbg_nopr_sha256" /* this is the RNG name */
+    };
+
+
+Depending on the RNG type, the RNG must be seeded. The seed is provided
+using the setsockopt interface to set the key. For example, the
+ansi_cprng requires a seed. The DRBGs do not require a seed, but may be
+seeded. The seed is also known as a *Personalization String* in NIST SP 800-90A
+standard.
+
+Using the read()/recvmsg() system calls, random numbers can be obtained.
+The kernel generates at most 128 bytes in one call. If user space
+requires more data, multiple calls to read()/recvmsg() must be made.
+
+WARNING: The user space caller may invoke the initially mentioned accept
+system call multiple times. In this case, the returned file descriptors
+have the same state.
+
+Following CAVP testing interfaces are enabled when kernel is built with
+CRYPTO_USER_API_RNG_CAVP option:
+
+-  the concatenation of *Entropy* and *Nonce* can be provided to the RNG via
+   ALG_SET_DRBG_ENTROPY setsockopt interface. Setting the entropy requires
+   CAP_SYS_ADMIN permission.
+
+-  *Additional Data* can be provided using the send()/sendmsg() system calls,
+   but only after the entropy has been set.
+
+Zero-Copy Interface
+-------------------
+
+In addition to the send/write/read/recv system call family, the AF_ALG
+interface can be accessed with the zero-copy interface of
+splice/vmsplice. As the name indicates, the kernel tries to avoid a copy
+operation into kernel space.
+
+The zero-copy operation requires data to be aligned at the page
+boundary. Non-aligned data can be used as well, but may require more
+operations of the kernel which would defeat the speed gains obtained
+from the zero-copy interface.
+
+The system-inherent limit for the size of one zero-copy operation is 16
+pages. If more data is to be sent to AF_ALG, user space must slice the
+input into segments with a maximum size of 16 pages.
+
+Zero-copy can be used with the following code example (a complete
+working example is provided with libkcapi):
+
+::
+
+    int pipes[2];
+
+    pipe(pipes);
+    /* input data in iov */
+    vmsplice(pipes[1], iov, iovlen, SPLICE_F_GIFT);
+    /* opfd is the file descriptor returned from accept() system call */
+    splice(pipes[0], NULL, opfd, NULL, ret, 0);
+    read(opfd, out, outlen);
+
+
+Setsockopt Interface
+--------------------
+
+In addition to the read/recv and send/write system call handling to send
+and retrieve data subject to the cipher operation, a consumer also needs
+to set the additional information for the cipher operation. This
+additional information is set using the setsockopt system call that must
+be invoked with the file descriptor of the open cipher (i.e. the file
+descriptor returned by the accept system call).
+
+Each setsockopt invocation must use the level SOL_ALG.
+
+The setsockopt interface allows setting the following data using the
+mentioned optname:
+
+-  ALG_SET_KEY -- Setting the key. Key setting is applicable to:
+
+   -  the skcipher cipher type (symmetric ciphers)
+
+   -  the hash cipher type (keyed message digests)
+
+   -  the AEAD cipher type
+
+   -  the RNG cipher type to provide the seed
+
+-  ALG_SET_AEAD_AUTHSIZE -- Setting the authentication tag size for
+   AEAD ciphers. For a encryption operation, the authentication tag of
+   the given size will be generated. For a decryption operation, the
+   provided ciphertext is assumed to contain an authentication tag of
+   the given size (see section about AEAD memory layout below).
+
+-  ALG_SET_DRBG_ENTROPY -- Setting the entropy of the random number generator.
+   This option is applicable to RNG cipher type only.
+
+User space API example
+----------------------
+
+Please see [1] for libkcapi which provides an easy-to-use wrapper around
+the aforementioned Netlink kernel interface. [1] also contains a test
+application that invokes all libkcapi API calls.
+
+[1] https://www.chronox.de/libkcapi.html