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-rw-r--r--kernel/Documentation/crypto/api-intro.txt248
-rw-r--r--kernel/Documentation/crypto/asymmetric-keys.txt312
-rw-r--r--kernel/Documentation/crypto/async-tx-api.txt225
-rw-r--r--kernel/Documentation/crypto/descore-readme.txt352
4 files changed, 1137 insertions, 0 deletions
diff --git a/kernel/Documentation/crypto/api-intro.txt b/kernel/Documentation/crypto/api-intro.txt
new file mode 100644
index 000000000..8b4930271
--- /dev/null
+++ b/kernel/Documentation/crypto/api-intro.txt
@@ -0,0 +1,248 @@
+
+ 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).
+
+Support for hardware crypto devices via an asynchronous interface is
+under development.
+
+Here's an example of how to use the API:
+
+ #include <linux/crypto.h>
+ #include <linux/err.h>
+ #include <linux/scatterlist.h>
+
+ struct scatterlist sg[2];
+ char result[128];
+ struct crypto_hash *tfm;
+ struct hash_desc desc;
+
+ tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
+ if (IS_ERR(tfm))
+ fail();
+
+ /* ... set up the scatterlists ... */
+
+ desc.tfm = tfm;
+ desc.flags = 0;
+
+ if (crypto_hash_digest(&desc, sg, 2, result))
+ fail();
+
+ crypto_free_hash(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 (http://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/kernel/Documentation/crypto/asymmetric-keys.txt b/kernel/Documentation/crypto/asymmetric-keys.txt
new file mode 100644
index 000000000..b7675904a
--- /dev/null
+++ b/kernel/Documentation/crypto/asymmetric-keys.txt
@@ -0,0 +1,312 @@
+ =============================================
+ ASYMMETRIC / PUBLIC-KEY CRYPTOGRAPHY KEY TYPE
+ =============================================
+
+Contents:
+
+ - Overview.
+ - Key identification.
+ - Accessing asymmetric keys.
+ - Signature verification.
+ - Asymmetric key subtypes.
+ - Instantiation data parsers.
+
+
+========
+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 asymmetri 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 (*verify_signature)(const struct key *key,
+ const struct public_key_signature *sig);
+ };
+
+Asymmetric keys point to this with their type_data[0] 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) verify_signature().
+
+ Optional. These are the entry points for the key usage operations.
+ Currently there is only the one defined. If not set, the caller will be
+ given -ENOTSUPP. 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.
+
+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.txt].
+
+ struct key_preparsed_payload {
+ char *description;
+ void *type_data[2];
+ void *payload;
+ 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, ->type_data[0] should be set to
+ point to the subtype to be used, ->payload should be set to point to the
+ initialised data for that subtype, ->type_data[1] should point to a hex
+ fingerprint and quotalen should be updated to indicate how much quota this
+ key should account for.
+
+ When clearing up, the data attached to ->type_data[1] and ->description
+ will be kfree()'d and the data attached to ->payload will be passed to the
+ subtype's ->destroy() method to be disposed of. A module reference for
+ the subtype pointed to by ->type_data[0] 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.
diff --git a/kernel/Documentation/crypto/async-tx-api.txt b/kernel/Documentation/crypto/async-tx-api.txt
new file mode 100644
index 000000000..7bf1be20d
--- /dev/null
+++ b/kernel/Documentation/crypto/async-tx-api.txt
@@ -0,0 +1,225 @@
+ Asynchronous Transfers/Transforms API
+
+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/kernel/Documentation/crypto/descore-readme.txt b/kernel/Documentation/crypto/descore-readme.txt
new file mode 100644
index 000000000..16e9e6350
--- /dev/null
+++ b/kernel/Documentation/crypto/descore-readme.txt
@@ -0,0 +1,352 @@
+Below is the original README file from the descore.shar package.
+------------------------------------------------------------------------------
+
+des - fast & portable DES encryption & decryption.
+Copyright (C) 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
+
+$Id: 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.