cregit-Linux how code gets into the kernel

Release 4.8 crypto/algif_aead.c

Directory: crypto
/*
 * algif_aead: User-space interface for AEAD algorithms
 *
 * Copyright (C) 2014, Stephan Mueller <smueller@chronox.de>
 *
 * This file provides the user-space API for AEAD ciphers.
 *
 * This file is derived from algif_skcipher.c.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 */

#include <crypto/internal/aead.h>
#include <crypto/scatterwalk.h>
#include <crypto/if_alg.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/net.h>
#include <net/sock.h>


struct aead_sg_list {
	
unsigned int cur;
	
struct scatterlist sg[ALG_MAX_PAGES];
};


struct aead_async_rsgl {
	
struct af_alg_sgl sgl;
	
struct list_head list;
};


struct aead_async_req {
	
struct scatterlist *tsgl;
	
struct aead_async_rsgl first_rsgl;
	
struct list_head list;
	
struct kiocb *iocb;
	
unsigned int tsgls;
	
char iv[];
};


struct aead_ctx {
	
struct aead_sg_list tsgl;
	
struct aead_async_rsgl first_rsgl;
	
struct list_head list;

	
void *iv;

	
struct af_alg_completion completion;

	
unsigned long used;

	
unsigned int len;
	
bool more;
	
bool merge;
	
bool enc;

	
size_t aead_assoclen;
	
struct aead_request aead_req;
};


static inline int aead_sndbuf(struct sock *sk) { struct alg_sock *ask = alg_sk(sk); struct aead_ctx *ctx = ask->private; return max_t(int, max_t(int, sk->sk_sndbuf & PAGE_MASK, PAGE_SIZE) - ctx->used, 0); }

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static inline bool aead_writable(struct sock *sk) { return PAGE_SIZE <= aead_sndbuf(sk); }

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static inline bool aead_sufficient_data(struct aead_ctx *ctx) { unsigned as = crypto_aead_authsize(crypto_aead_reqtfm(&ctx->aead_req)); return ctx->used >= ctx->aead_assoclen + as; }

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static void aead_reset_ctx(struct aead_ctx *ctx) { struct aead_sg_list *sgl = &ctx->tsgl; sg_init_table(sgl->sg, ALG_MAX_PAGES); sgl->cur = 0; ctx->used = 0; ctx->more = 0; ctx->merge = 0; }

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static void aead_put_sgl(struct sock *sk) { struct alg_sock *ask = alg_sk(sk); struct aead_ctx *ctx = ask->private; struct aead_sg_list *sgl = &ctx->tsgl; struct scatterlist *sg = sgl->sg; unsigned int i; for (i = 0; i < sgl->cur; i++) { if (!sg_page(sg + i)) continue; put_page(sg_page(sg + i)); sg_assign_page(sg + i, NULL); } aead_reset_ctx(ctx); }

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static void aead_wmem_wakeup(struct sock *sk) { struct socket_wq *wq; if (!aead_writable(sk)) return; rcu_read_lock(); wq = rcu_dereference(sk->sk_wq); if (skwq_has_sleeper(wq)) wake_up_interruptible_sync_poll(&wq->wait, POLLIN | POLLRDNORM | POLLRDBAND); sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN); rcu_read_unlock(); }

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static int aead_wait_for_data(struct sock *sk, unsigned flags) { struct alg_sock *ask = alg_sk(sk); struct aead_ctx *ctx = ask->private; long timeout; DEFINE_WAIT(wait); int err = -ERESTARTSYS; if (flags & MSG_DONTWAIT) return -EAGAIN; sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk); for (;;) { if (signal_pending(current)) break; prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE); timeout = MAX_SCHEDULE_TIMEOUT; if (sk_wait_event(sk, &timeout, !ctx->more)) { err = 0; break; } } finish_wait(sk_sleep(sk), &wait); sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk); return err; }

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static void aead_data_wakeup(struct sock *sk) { struct alg_sock *ask = alg_sk(sk); struct aead_ctx *ctx = ask->private; struct socket_wq *wq; if (ctx->more) return; if (!ctx->used) return; rcu_read_lock(); wq = rcu_dereference(sk->sk_wq); if (skwq_has_sleeper(wq)) wake_up_interruptible_sync_poll(&wq->wait, POLLOUT | POLLRDNORM | POLLRDBAND); sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT); rcu_read_unlock(); }

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static int aead_sendmsg(struct socket *sock, struct msghdr *msg, size_t size) { struct sock *sk = sock->sk; struct alg_sock *ask = alg_sk(sk); struct aead_ctx *ctx = ask->private; unsigned ivsize = crypto_aead_ivsize(crypto_aead_reqtfm(&ctx->aead_req)); struct aead_sg_list *sgl = &ctx->tsgl; struct af_alg_control con = {}; long copied = 0; bool enc = 0; bool init = 0; int err = -EINVAL; if (msg->msg_controllen) { err = af_alg_cmsg_send(msg, &con); if (err) return err; init = 1; switch (con.op) { case ALG_OP_ENCRYPT: enc = 1; break; case ALG_OP_DECRYPT: enc = 0; break; default: return -EINVAL; } if (con.iv && con.iv->ivlen != ivsize) return -EINVAL; } lock_sock(sk); if (!ctx->more && ctx->used) goto unlock; if (init) { ctx->enc = enc; if (con.iv) memcpy(ctx->iv, con.iv->iv, ivsize); ctx->aead_assoclen = con.aead_assoclen; } while (size) { size_t len = size; struct scatterlist *sg = NULL; /* use the existing memory in an allocated page */ if (ctx->merge) { sg = sgl->sg + sgl->cur - 1; len = min_t(unsigned long, len, PAGE_SIZE - sg->offset - sg->length); err = memcpy_from_msg(page_address(sg_page(sg)) + sg->offset + sg->length, msg, len); if (err) goto unlock; sg->length += len; ctx->merge = (sg->offset + sg->length) & (PAGE_SIZE - 1); ctx->used += len; copied += len; size -= len; continue; } if (!aead_writable(sk)) { /* user space sent too much data */ aead_put_sgl(sk); err = -EMSGSIZE; goto unlock; } /* allocate a new page */ len = min_t(unsigned long, size, aead_sndbuf(sk)); while (len) { size_t plen = 0; if (sgl->cur >= ALG_MAX_PAGES) { aead_put_sgl(sk); err = -E2BIG; goto unlock; } sg = sgl->sg + sgl->cur; plen = min_t(size_t, len, PAGE_SIZE); sg_assign_page(sg, alloc_page(GFP_KERNEL)); err = -ENOMEM; if (!sg_page(sg)) goto unlock; err = memcpy_from_msg(page_address(sg_page(sg)), msg, plen); if (err) { __free_page(sg_page(sg)); sg_assign_page(sg, NULL); goto unlock; } sg->offset = 0; sg->length = plen; len -= plen; ctx->used += plen; copied += plen; sgl->cur++; size -= plen; ctx->merge = plen & (PAGE_SIZE - 1); } } err = 0; ctx->more = msg->msg_flags & MSG_MORE; if (!ctx->more && !aead_sufficient_data(ctx)) { aead_put_sgl(sk); err = -EMSGSIZE; } unlock: aead_data_wakeup(sk); release_sock(sk); return err ?: copied; }

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static ssize_t aead_sendpage(struct socket *sock, struct page *page, int offset, size_t size, int flags) { struct sock *sk = sock->sk; struct alg_sock *ask = alg_sk(sk); struct aead_ctx *ctx = ask->private; struct aead_sg_list *sgl = &ctx->tsgl; int err = -EINVAL; if (flags & MSG_SENDPAGE_NOTLAST) flags |= MSG_MORE; if (sgl->cur >= ALG_MAX_PAGES) return -E2BIG; lock_sock(sk); if (!ctx->more && ctx->used) goto unlock; if (!size) goto done; if (!aead_writable(sk)) { /* user space sent too much data */ aead_put_sgl(sk); err = -EMSGSIZE; goto unlock; } ctx->merge = 0; get_page(page); sg_set_page(sgl->sg + sgl->cur, page, size, offset); sgl->cur++; ctx->used += size; err = 0; done: ctx->more = flags & MSG_MORE; if (!ctx->more && !aead_sufficient_data(ctx)) { aead_put_sgl(sk); err = -EMSGSIZE; } unlock: aead_data_wakeup(sk); release_sock(sk); return err ?: size; }

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#define GET_ASYM_REQ(req, tfm) (struct aead_async_req *) \ ((char *)req + sizeof(struct aead_request) + \ crypto_aead_reqsize(tfm)) #define GET_REQ_SIZE(tfm) sizeof(struct aead_async_req) + \ crypto_aead_reqsize(tfm) + crypto_aead_ivsize(tfm) + \ sizeof(struct aead_request)
static void aead_async_cb(struct crypto_async_request *_req, int err) { struct sock *sk = _req->data; struct alg_sock *ask = alg_sk(sk); struct aead_ctx *ctx = ask->private; struct crypto_aead *tfm = crypto_aead_reqtfm(&ctx->aead_req); struct aead_request *req = aead_request_cast(_req); struct aead_async_req *areq = GET_ASYM_REQ(req, tfm); struct scatterlist *sg = areq->tsgl; struct aead_async_rsgl *rsgl; struct kiocb *iocb = areq->iocb; unsigned int i, reqlen = GET_REQ_SIZE(tfm); list_for_each_entry(rsgl, &areq->list, list) { af_alg_free_sg(&rsgl->sgl); if (rsgl != &areq->first_rsgl) sock_kfree_s(sk, rsgl, sizeof(*rsgl)); } for (i = 0; i < areq->tsgls; i++) put_page(sg_page(sg + i)); sock_kfree_s(sk, areq->tsgl, sizeof(*areq->tsgl) * areq->tsgls); sock_kfree_s(sk, req, reqlen); __sock_put(sk); iocb->ki_complete(iocb, err, err); }

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static int aead_recvmsg_async(struct socket *sock, struct msghdr *msg, int flags) { struct sock *sk = sock->sk; struct alg_sock *ask = alg_sk(sk); struct aead_ctx *ctx = ask->private; struct crypto_aead *tfm = crypto_aead_reqtfm(&ctx->aead_req); struct aead_async_req *areq; struct aead_request *req = NULL; struct aead_sg_list *sgl = &ctx->tsgl; struct aead_async_rsgl *last_rsgl = NULL, *rsgl; unsigned int as = crypto_aead_authsize(tfm); unsigned int i, reqlen = GET_REQ_SIZE(tfm); int err = -ENOMEM; unsigned long used; size_t outlen; size_t usedpages = 0; lock_sock(sk); if (ctx->more) { err = aead_wait_for_data(sk, flags); if (err) goto unlock; } used = ctx->used; outlen = used; if (!aead_sufficient_data(ctx)) goto unlock; req = sock_kmalloc(sk, reqlen, GFP_KERNEL); if (unlikely(!req)) goto unlock; areq = GET_ASYM_REQ(req, tfm); memset(&areq->first_rsgl, '\0', sizeof(areq->first_rsgl)); INIT_LIST_HEAD(&areq->list); areq->iocb = msg->msg_iocb; memcpy(areq->iv, ctx->iv, crypto_aead_ivsize(tfm)); aead_request_set_tfm(req, tfm); aead_request_set_ad(req, ctx->aead_assoclen); aead_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, aead_async_cb, sk); used -= ctx->aead_assoclen + (ctx->enc ? as : 0); /* take over all tx sgls from ctx */ areq->tsgl = sock_kmalloc(sk, sizeof(*areq->tsgl) * sgl->cur, GFP_KERNEL); if (unlikely(!areq->tsgl)) goto free; sg_init_table(areq->tsgl, sgl->cur); for (i = 0; i < sgl->cur; i++) sg_set_page(&areq->tsgl[i], sg_page(&sgl->sg[i]), sgl->sg[i].length, sgl->sg[i].offset); areq->tsgls = sgl->cur; /* create rx sgls */ while (iov_iter_count(&msg->msg_iter)) { size_t seglen = min_t(size_t, iov_iter_count(&msg->msg_iter), (outlen - usedpages)); if (list_empty(&areq->list)) { rsgl = &areq->first_rsgl; } else { rsgl = sock_kmalloc(sk, sizeof(*rsgl), GFP_KERNEL); if (unlikely(!rsgl)) { err = -ENOMEM; goto free; } } rsgl->sgl.npages = 0; list_add_tail(&rsgl->list, &areq->list); /* make one iovec available as scatterlist */ err = af_alg_make_sg(&rsgl->sgl, &msg->msg_iter, seglen); if (err < 0) goto free; usedpages += err; /* chain the new scatterlist with previous one */ if (last_rsgl) af_alg_link_sg(&last_rsgl->sgl, &rsgl->sgl); last_rsgl = rsgl; /* we do not need more iovecs as we have sufficient memory */ if (outlen <= usedpages) break; iov_iter_advance(&msg->msg_iter, err); } err = -EINVAL; /* ensure output buffer is sufficiently large */ if (usedpages < outlen) goto free; aead_request_set_crypt(req, areq->tsgl, areq->first_rsgl.sgl.sg, used, areq->iv); err = ctx->enc ? crypto_aead_encrypt(req) : crypto_aead_decrypt(req); if (err) { if (err == -EINPROGRESS) { sock_hold(sk); err = -EIOCBQUEUED; aead_reset_ctx(ctx); goto unlock; } else if (err == -EBADMSG) { aead_put_sgl(sk); } goto free; } aead_put_sgl(sk); free: list_for_each_entry(rsgl, &areq->list, list) { af_alg_free_sg(&rsgl->sgl); if (rsgl != &areq->first_rsgl) sock_kfree_s(sk, rsgl, sizeof(*rsgl)); } if (areq->tsgl) sock_kfree_s(sk, areq->tsgl, sizeof(*areq->tsgl) * areq->tsgls); if (req) sock_kfree_s(sk, req, reqlen); unlock: aead_wmem_wakeup(sk); release_sock(sk); return err ? err : outlen; }

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static int aead_recvmsg_sync(struct socket *sock, struct msghdr *msg, int flags) { struct sock *sk = sock->sk; struct alg_sock *ask = alg_sk(sk); struct aead_ctx *ctx = ask->private; unsigned as = crypto_aead_authsize(crypto_aead_reqtfm(&ctx->aead_req)); struct aead_sg_list *sgl = &ctx->tsgl; struct aead_async_rsgl *last_rsgl = NULL; struct aead_async_rsgl *rsgl, *tmp; int err = -EINVAL; unsigned long used = 0; size_t outlen = 0; size_t usedpages = 0; lock_sock(sk); /* * AEAD memory structure: For encryption, the tag is appended to the * ciphertext which implies that the memory allocated for the ciphertext * must be increased by the tag length. For decryption, the tag * is expected to be concatenated to the ciphertext. The plaintext * therefore has a memory size of the ciphertext minus the tag length. * * The memory structure for cipher operation has the following * structure: * AEAD encryption input: assoc data || plaintext * AEAD encryption output: cipherntext || auth tag * AEAD decryption input: assoc data || ciphertext || auth tag * AEAD decryption output: plaintext */ if (ctx->more) { err = aead_wait_for_data(sk, flags); if (err) goto unlock; } used = ctx->used; /* * Make sure sufficient data is present -- note, the same check is * is also present in sendmsg/sendpage. The checks in sendpage/sendmsg * shall provide an information to the data sender that something is * wrong, but they are irrelevant to maintain the kernel integrity. * We need this check here too in case user space decides to not honor * the error message in sendmsg/sendpage and still call recvmsg. This * check here protects the kernel integrity. */ if (!aead_sufficient_data(ctx)) goto unlock; outlen = used; /* * The cipher operation input data is reduced by the associated data * length as this data is processed separately later on. */ used -= ctx->aead_assoclen + (ctx->enc ? as : 0); /* convert iovecs of output buffers into scatterlists */ while (iov_iter_count(&msg->msg_iter)) { size_t seglen = min_t(size_t, iov_iter_count(&msg->msg_iter), (outlen - usedpages)); if (list_empty(&ctx->list)) { rsgl = &ctx->first_rsgl; } else { rsgl = sock_kmalloc(sk, sizeof(*rsgl), GFP_KERNEL); if (unlikely(!rsgl)) { err = -ENOMEM; goto unlock; } } rsgl->sgl.npages = 0; list_add_tail(&rsgl->list, &ctx->list); /* make one iovec available as scatterlist */ err = af_alg_make_sg(&rsgl->sgl, &msg->msg_iter, seglen); if (err < 0) goto unlock; usedpages += err; /* chain the new scatterlist with previous one */ if (last_rsgl) af_alg_link_sg(&last_rsgl->sgl, &rsgl->sgl); last_rsgl = rsgl; /* we do not need more iovecs as we have sufficient memory */ if (outlen <= usedpages) break; iov_iter_advance(&msg->msg_iter, err); } err = -EINVAL; /* ensure output buffer is sufficiently large */ if (usedpages < outlen) goto unlock; sg_mark_end(sgl->sg + sgl