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605 lines
16 KiB
605 lines
16 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* algif_aead: User-space interface for AEAD algorithms |
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* |
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* Copyright (C) 2014, Stephan Mueller <[email protected]> |
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* |
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* This file provides the user-space API for AEAD ciphers. |
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* |
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* The following concept of the memory management is used: |
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* |
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* The kernel maintains two SGLs, the TX SGL and the RX SGL. The TX SGL is |
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* filled by user space with the data submitted via sendpage/sendmsg. Filling |
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* up the TX SGL does not cause a crypto operation -- the data will only be |
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* tracked by the kernel. Upon receipt of one recvmsg call, the caller must |
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* provide a buffer which is tracked with the RX SGL. |
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* |
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* During the processing of the recvmsg operation, the cipher request is |
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* allocated and prepared. As part of the recvmsg operation, the processed |
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* TX buffers are extracted from the TX SGL into a separate SGL. |
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* |
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* After the completion of the crypto operation, the RX SGL and the cipher |
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* request is released. The extracted TX SGL parts are released together with |
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* the RX SGL release. |
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*/ |
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|
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#include <crypto/internal/aead.h> |
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#include <crypto/scatterwalk.h> |
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#include <crypto/if_alg.h> |
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#include <crypto/skcipher.h> |
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#include <crypto/null.h> |
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#include <linux/init.h> |
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#include <linux/list.h> |
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#include <linux/kernel.h> |
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#include <linux/mm.h> |
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#include <linux/module.h> |
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#include <linux/net.h> |
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#include <net/sock.h> |
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|
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struct aead_tfm { |
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struct crypto_aead *aead; |
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struct crypto_sync_skcipher *null_tfm; |
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}; |
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|
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static inline bool aead_sufficient_data(struct sock *sk) |
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{ |
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struct alg_sock *ask = alg_sk(sk); |
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struct sock *psk = ask->parent; |
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struct alg_sock *pask = alg_sk(psk); |
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struct af_alg_ctx *ctx = ask->private; |
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struct aead_tfm *aeadc = pask->private; |
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struct crypto_aead *tfm = aeadc->aead; |
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unsigned int as = crypto_aead_authsize(tfm); |
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|
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/* |
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* The minimum amount of memory needed for an AEAD cipher is |
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* the AAD and in case of decryption the tag. |
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*/ |
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return ctx->used >= ctx->aead_assoclen + (ctx->enc ? 0 : as); |
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} |
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static int aead_sendmsg(struct socket *sock, struct msghdr *msg, size_t size) |
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{ |
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struct sock *sk = sock->sk; |
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struct alg_sock *ask = alg_sk(sk); |
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struct sock *psk = ask->parent; |
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struct alg_sock *pask = alg_sk(psk); |
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struct aead_tfm *aeadc = pask->private; |
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struct crypto_aead *tfm = aeadc->aead; |
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unsigned int ivsize = crypto_aead_ivsize(tfm); |
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return af_alg_sendmsg(sock, msg, size, ivsize); |
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} |
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static int crypto_aead_copy_sgl(struct crypto_sync_skcipher *null_tfm, |
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struct scatterlist *src, |
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struct scatterlist *dst, unsigned int len) |
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{ |
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SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, null_tfm); |
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skcipher_request_set_sync_tfm(skreq, null_tfm); |
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skcipher_request_set_callback(skreq, CRYPTO_TFM_REQ_MAY_SLEEP, |
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NULL, NULL); |
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skcipher_request_set_crypt(skreq, src, dst, len, NULL); |
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|
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return crypto_skcipher_encrypt(skreq); |
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} |
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static int _aead_recvmsg(struct socket *sock, struct msghdr *msg, |
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size_t ignored, int flags) |
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{ |
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struct sock *sk = sock->sk; |
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struct alg_sock *ask = alg_sk(sk); |
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struct sock *psk = ask->parent; |
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struct alg_sock *pask = alg_sk(psk); |
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struct af_alg_ctx *ctx = ask->private; |
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struct aead_tfm *aeadc = pask->private; |
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struct crypto_aead *tfm = aeadc->aead; |
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struct crypto_sync_skcipher *null_tfm = aeadc->null_tfm; |
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unsigned int i, as = crypto_aead_authsize(tfm); |
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struct af_alg_async_req *areq; |
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struct af_alg_tsgl *tsgl, *tmp; |
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struct scatterlist *rsgl_src, *tsgl_src = NULL; |
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int err = 0; |
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size_t used = 0; /* [in] TX bufs to be en/decrypted */ |
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size_t outlen = 0; /* [out] RX bufs produced by kernel */ |
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size_t usedpages = 0; /* [in] RX bufs to be used from user */ |
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size_t processed = 0; /* [in] TX bufs to be consumed */ |
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|
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if (!ctx->init || ctx->more) { |
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err = af_alg_wait_for_data(sk, flags, 0); |
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if (err) |
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return err; |
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} |
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/* |
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* Data length provided by caller via sendmsg/sendpage that has not |
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* yet been processed. |
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*/ |
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used = ctx->used; |
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/* |
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* Make sure sufficient data is present -- note, the same check is |
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* also present in sendmsg/sendpage. The checks in sendpage/sendmsg |
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* shall provide an information to the data sender that something is |
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* wrong, but they are irrelevant to maintain the kernel integrity. |
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* We need this check here too in case user space decides to not honor |
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* the error message in sendmsg/sendpage and still call recvmsg. This |
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* check here protects the kernel integrity. |
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*/ |
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if (!aead_sufficient_data(sk)) |
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return -EINVAL; |
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/* |
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* Calculate the minimum output buffer size holding the result of the |
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* cipher operation. When encrypting data, the receiving buffer is |
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* larger by the tag length compared to the input buffer as the |
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* encryption operation generates the tag. For decryption, the input |
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* buffer provides the tag which is consumed resulting in only the |
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* plaintext without a buffer for the tag returned to the caller. |
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*/ |
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if (ctx->enc) |
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outlen = used + as; |
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else |
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outlen = used - as; |
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|
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/* |
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* The cipher operation input data is reduced by the associated data |
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* length as this data is processed separately later on. |
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*/ |
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used -= ctx->aead_assoclen; |
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|
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/* Allocate cipher request for current operation. */ |
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areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) + |
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crypto_aead_reqsize(tfm)); |
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if (IS_ERR(areq)) |
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return PTR_ERR(areq); |
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|
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/* convert iovecs of output buffers into RX SGL */ |
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err = af_alg_get_rsgl(sk, msg, flags, areq, outlen, &usedpages); |
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if (err) |
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goto free; |
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/* |
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* Ensure output buffer is sufficiently large. If the caller provides |
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* less buffer space, only use the relative required input size. This |
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* allows AIO operation where the caller sent all data to be processed |
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* and the AIO operation performs the operation on the different chunks |
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* of the input data. |
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*/ |
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if (usedpages < outlen) { |
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size_t less = outlen - usedpages; |
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if (used < less) { |
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err = -EINVAL; |
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goto free; |
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} |
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used -= less; |
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outlen -= less; |
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} |
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processed = used + ctx->aead_assoclen; |
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list_for_each_entry_safe(tsgl, tmp, &ctx->tsgl_list, list) { |
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for (i = 0; i < tsgl->cur; i++) { |
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struct scatterlist *process_sg = tsgl->sg + i; |
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if (!(process_sg->length) || !sg_page(process_sg)) |
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continue; |
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tsgl_src = process_sg; |
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break; |
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} |
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if (tsgl_src) |
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break; |
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} |
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if (processed && !tsgl_src) { |
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err = -EFAULT; |
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goto free; |
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} |
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/* |
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* Copy of AAD from source to destination |
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* |
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* The AAD is copied to the destination buffer without change. Even |
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* when user space uses an in-place cipher operation, the kernel |
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* will copy the data as it does not see whether such in-place operation |
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* is initiated. |
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* |
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* To ensure efficiency, the following implementation ensure that the |
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* ciphers are invoked to perform a crypto operation in-place. This |
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* is achieved by memory management specified as follows. |
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*/ |
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/* Use the RX SGL as source (and destination) for crypto op. */ |
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rsgl_src = areq->first_rsgl.sgl.sg; |
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if (ctx->enc) { |
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/* |
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* Encryption operation - The in-place cipher operation is |
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* achieved by the following operation: |
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* |
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* TX SGL: AAD || PT |
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* | | |
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* | copy | |
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* v v |
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* RX SGL: AAD || PT || Tag |
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*/ |
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err = crypto_aead_copy_sgl(null_tfm, tsgl_src, |
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areq->first_rsgl.sgl.sg, processed); |
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if (err) |
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goto free; |
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af_alg_pull_tsgl(sk, processed, NULL, 0); |
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} else { |
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/* |
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* Decryption operation - To achieve an in-place cipher |
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* operation, the following SGL structure is used: |
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* |
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* TX SGL: AAD || CT || Tag |
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* | | ^ |
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* | copy | | Create SGL link. |
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* v v | |
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* RX SGL: AAD || CT ----+ |
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*/ |
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/* Copy AAD || CT to RX SGL buffer for in-place operation. */ |
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err = crypto_aead_copy_sgl(null_tfm, tsgl_src, |
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areq->first_rsgl.sgl.sg, outlen); |
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if (err) |
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goto free; |
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/* Create TX SGL for tag and chain it to RX SGL. */ |
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areq->tsgl_entries = af_alg_count_tsgl(sk, processed, |
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processed - as); |
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if (!areq->tsgl_entries) |
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areq->tsgl_entries = 1; |
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areq->tsgl = sock_kmalloc(sk, array_size(sizeof(*areq->tsgl), |
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areq->tsgl_entries), |
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GFP_KERNEL); |
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if (!areq->tsgl) { |
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err = -ENOMEM; |
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goto free; |
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} |
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sg_init_table(areq->tsgl, areq->tsgl_entries); |
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|
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/* Release TX SGL, except for tag data and reassign tag data. */ |
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af_alg_pull_tsgl(sk, processed, areq->tsgl, processed - as); |
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|
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/* chain the areq TX SGL holding the tag with RX SGL */ |
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if (usedpages) { |
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/* RX SGL present */ |
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struct af_alg_sgl *sgl_prev = &areq->last_rsgl->sgl; |
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sg_unmark_end(sgl_prev->sg + sgl_prev->npages - 1); |
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sg_chain(sgl_prev->sg, sgl_prev->npages + 1, |
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areq->tsgl); |
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} else |
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/* no RX SGL present (e.g. authentication only) */ |
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rsgl_src = areq->tsgl; |
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} |
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|
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/* Initialize the crypto operation */ |
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aead_request_set_crypt(&areq->cra_u.aead_req, rsgl_src, |
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areq->first_rsgl.sgl.sg, used, ctx->iv); |
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aead_request_set_ad(&areq->cra_u.aead_req, ctx->aead_assoclen); |
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aead_request_set_tfm(&areq->cra_u.aead_req, tfm); |
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|
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if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) { |
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/* AIO operation */ |
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sock_hold(sk); |
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areq->iocb = msg->msg_iocb; |
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|
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/* Remember output size that will be generated. */ |
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areq->outlen = outlen; |
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aead_request_set_callback(&areq->cra_u.aead_req, |
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CRYPTO_TFM_REQ_MAY_SLEEP, |
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af_alg_async_cb, areq); |
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err = ctx->enc ? crypto_aead_encrypt(&areq->cra_u.aead_req) : |
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crypto_aead_decrypt(&areq->cra_u.aead_req); |
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/* AIO operation in progress */ |
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if (err == -EINPROGRESS) |
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return -EIOCBQUEUED; |
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sock_put(sk); |
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} else { |
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/* Synchronous operation */ |
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aead_request_set_callback(&areq->cra_u.aead_req, |
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CRYPTO_TFM_REQ_MAY_SLEEP | |
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CRYPTO_TFM_REQ_MAY_BACKLOG, |
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crypto_req_done, &ctx->wait); |
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err = crypto_wait_req(ctx->enc ? |
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crypto_aead_encrypt(&areq->cra_u.aead_req) : |
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crypto_aead_decrypt(&areq->cra_u.aead_req), |
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&ctx->wait); |
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} |
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free: |
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af_alg_free_resources(areq); |
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return err ? err : outlen; |
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} |
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static int aead_recvmsg(struct socket *sock, struct msghdr *msg, |
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size_t ignored, int flags) |
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{ |
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struct sock *sk = sock->sk; |
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int ret = 0; |
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lock_sock(sk); |
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while (msg_data_left(msg)) { |
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int err = _aead_recvmsg(sock, msg, ignored, flags); |
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/* |
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* This error covers -EIOCBQUEUED which implies that we can |
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* only handle one AIO request. If the caller wants to have |
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* multiple AIO requests in parallel, he must make multiple |
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* separate AIO calls. |
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* |
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* Also return the error if no data has been processed so far. |
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*/ |
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if (err <= 0) { |
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if (err == -EIOCBQUEUED || err == -EBADMSG || !ret) |
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ret = err; |
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goto out; |
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} |
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ret += err; |
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} |
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out: |
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af_alg_wmem_wakeup(sk); |
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release_sock(sk); |
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return ret; |
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} |
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static struct proto_ops algif_aead_ops = { |
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.family = PF_ALG, |
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.connect = sock_no_connect, |
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.socketpair = sock_no_socketpair, |
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.getname = sock_no_getname, |
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.ioctl = sock_no_ioctl, |
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.listen = sock_no_listen, |
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.shutdown = sock_no_shutdown, |
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.mmap = sock_no_mmap, |
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.bind = sock_no_bind, |
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.accept = sock_no_accept, |
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.release = af_alg_release, |
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.sendmsg = aead_sendmsg, |
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.sendpage = af_alg_sendpage, |
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.recvmsg = aead_recvmsg, |
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.poll = af_alg_poll, |
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}; |
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static int aead_check_key(struct socket *sock) |
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{ |
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int err = 0; |
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struct sock *psk; |
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struct alg_sock *pask; |
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struct aead_tfm *tfm; |
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struct sock *sk = sock->sk; |
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struct alg_sock *ask = alg_sk(sk); |
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lock_sock(sk); |
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if (!atomic_read(&ask->nokey_refcnt)) |
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goto unlock_child; |
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psk = ask->parent; |
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pask = alg_sk(ask->parent); |
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tfm = pask->private; |
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err = -ENOKEY; |
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lock_sock_nested(psk, SINGLE_DEPTH_NESTING); |
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if (crypto_aead_get_flags(tfm->aead) & CRYPTO_TFM_NEED_KEY) |
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goto unlock; |
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atomic_dec(&pask->nokey_refcnt); |
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atomic_set(&ask->nokey_refcnt, 0); |
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err = 0; |
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unlock: |
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release_sock(psk); |
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unlock_child: |
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release_sock(sk); |
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return err; |
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} |
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static int aead_sendmsg_nokey(struct socket *sock, struct msghdr *msg, |
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size_t size) |
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{ |
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int err; |
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err = aead_check_key(sock); |
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if (err) |
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return err; |
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return aead_sendmsg(sock, msg, size); |
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} |
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static ssize_t aead_sendpage_nokey(struct socket *sock, struct page *page, |
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int offset, size_t size, int flags) |
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{ |
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int err; |
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err = aead_check_key(sock); |
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if (err) |
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return err; |
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return af_alg_sendpage(sock, page, offset, size, flags); |
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} |
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static int aead_recvmsg_nokey(struct socket *sock, struct msghdr *msg, |
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size_t ignored, int flags) |
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{ |
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int err; |
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err = aead_check_key(sock); |
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if (err) |
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return err; |
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return aead_recvmsg(sock, msg, ignored, flags); |
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} |
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static struct proto_ops algif_aead_ops_nokey = { |
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.family = PF_ALG, |
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|
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.connect = sock_no_connect, |
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.socketpair = sock_no_socketpair, |
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.getname = sock_no_getname, |
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.ioctl = sock_no_ioctl, |
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.listen = sock_no_listen, |
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.shutdown = sock_no_shutdown, |
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.mmap = sock_no_mmap, |
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.bind = sock_no_bind, |
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.accept = sock_no_accept, |
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|
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.release = af_alg_release, |
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.sendmsg = aead_sendmsg_nokey, |
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.sendpage = aead_sendpage_nokey, |
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.recvmsg = aead_recvmsg_nokey, |
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.poll = af_alg_poll, |
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}; |
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|
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static void *aead_bind(const char *name, u32 type, u32 mask) |
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{ |
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struct aead_tfm *tfm; |
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struct crypto_aead *aead; |
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struct crypto_sync_skcipher *null_tfm; |
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|
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tfm = kzalloc(sizeof(*tfm), GFP_KERNEL); |
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if (!tfm) |
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return ERR_PTR(-ENOMEM); |
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|
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aead = crypto_alloc_aead(name, type, mask); |
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if (IS_ERR(aead)) { |
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kfree(tfm); |
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return ERR_CAST(aead); |
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} |
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null_tfm = crypto_get_default_null_skcipher(); |
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if (IS_ERR(null_tfm)) { |
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crypto_free_aead(aead); |
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kfree(tfm); |
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return ERR_CAST(null_tfm); |
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} |
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|
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tfm->aead = aead; |
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tfm->null_tfm = null_tfm; |
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|
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return tfm; |
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} |
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static void aead_release(void *private) |
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{ |
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struct aead_tfm *tfm = private; |
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|
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crypto_free_aead(tfm->aead); |
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crypto_put_default_null_skcipher(); |
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kfree(tfm); |
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} |
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static int aead_setauthsize(void *private, unsigned int authsize) |
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{ |
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struct aead_tfm *tfm = private; |
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|
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return crypto_aead_setauthsize(tfm->aead, authsize); |
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} |
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|
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static int aead_setkey(void *private, const u8 *key, unsigned int keylen) |
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{ |
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struct aead_tfm *tfm = private; |
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|
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return crypto_aead_setkey(tfm->aead, key, keylen); |
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} |
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|
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static void aead_sock_destruct(struct sock *sk) |
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{ |
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struct alg_sock *ask = alg_sk(sk); |
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struct af_alg_ctx *ctx = ask->private; |
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struct sock *psk = ask->parent; |
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struct alg_sock *pask = alg_sk(psk); |
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struct aead_tfm *aeadc = pask->private; |
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struct crypto_aead *tfm = aeadc->aead; |
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unsigned int ivlen = crypto_aead_ivsize(tfm); |
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|
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af_alg_pull_tsgl(sk, ctx->used, NULL, 0); |
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sock_kzfree_s(sk, ctx->iv, ivlen); |
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sock_kfree_s(sk, ctx, ctx->len); |
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af_alg_release_parent(sk); |
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} |
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|
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static int aead_accept_parent_nokey(void *private, struct sock *sk) |
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{ |
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struct af_alg_ctx *ctx; |
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struct alg_sock *ask = alg_sk(sk); |
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struct aead_tfm *tfm = private; |
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struct crypto_aead *aead = tfm->aead; |
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unsigned int len = sizeof(*ctx); |
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unsigned int ivlen = crypto_aead_ivsize(aead); |
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|
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ctx = sock_kmalloc(sk, len, GFP_KERNEL); |
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if (!ctx) |
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return -ENOMEM; |
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memset(ctx, 0, len); |
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|
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ctx->iv = sock_kmalloc(sk, ivlen, GFP_KERNEL); |
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if (!ctx->iv) { |
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sock_kfree_s(sk, ctx, len); |
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return -ENOMEM; |
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} |
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memset(ctx->iv, 0, ivlen); |
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|
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INIT_LIST_HEAD(&ctx->tsgl_list); |
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ctx->len = len; |
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crypto_init_wait(&ctx->wait); |
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|
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ask->private = ctx; |
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|
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sk->sk_destruct = aead_sock_destruct; |
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|
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return 0; |
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} |
|
|
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static int aead_accept_parent(void *private, struct sock *sk) |
|
{ |
|
struct aead_tfm *tfm = private; |
|
|
|
if (crypto_aead_get_flags(tfm->aead) & CRYPTO_TFM_NEED_KEY) |
|
return -ENOKEY; |
|
|
|
return aead_accept_parent_nokey(private, sk); |
|
} |
|
|
|
static const struct af_alg_type algif_type_aead = { |
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.bind = aead_bind, |
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.release = aead_release, |
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.setkey = aead_setkey, |
|
.setauthsize = aead_setauthsize, |
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.accept = aead_accept_parent, |
|
.accept_nokey = aead_accept_parent_nokey, |
|
.ops = &algif_aead_ops, |
|
.ops_nokey = &algif_aead_ops_nokey, |
|
.name = "aead", |
|
.owner = THIS_MODULE |
|
}; |
|
|
|
static int __init algif_aead_init(void) |
|
{ |
|
return af_alg_register_type(&algif_type_aead); |
|
} |
|
|
|
static void __exit algif_aead_exit(void) |
|
{ |
|
int err = af_alg_unregister_type(&algif_type_aead); |
|
BUG_ON(err); |
|
} |
|
|
|
module_init(algif_aead_init); |
|
module_exit(algif_aead_exit); |
|
MODULE_LICENSE("GPL"); |
|
MODULE_AUTHOR("Stephan Mueller <[email protected]>"); |
|
MODULE_DESCRIPTION("AEAD kernel crypto API user space interface");
|
|
|