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Date: Mon, 09 Feb 2015 14:33:48 +0100
From: Stephan Mueller <smueller@...onox.de>
To: Al Viro <viro@...iv.linux.org.uk>
Cc: David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
linux-crypto@...r.kernel.org
Subject: Re: [PATCH v3 12/18] crypto: switch af_alg_make_sg() to iov_iter
Am Mittwoch, 4. Februar 2015, 06:40:03 schrieb Al Viro:
Hi Al,
> From: Al Viro <viro@...iv.linux.org.uk>
>
> With that, all ->sendmsg() instances are converted to iov_iter primitives
> and are agnostic wrt the kind of iov_iter they are working with.
> So's the last remaining ->recvmsg() instance that wasn't kind-agnostic yet.
> All ->sendmsg() and ->recvmsg() advance ->msg_iter by the amount actually
> copied and none of them modifies the underlying iovec, etc.
>
> Cc: linux-crypto@...r.kernel.org
> Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
> ---
> crypto/af_alg.c | 40 ++++++++------------------
> crypto/algif_hash.c | 45 ++++++++++++------------------
> crypto/algif_skcipher.c | 74
> ++++++++++++++++++++++--------------------------- include/crypto/if_alg.h |
> 3 +-
> 4 files changed, 62 insertions(+), 100 deletions(-)
>
> diff --git a/crypto/af_alg.c b/crypto/af_alg.c
> index 4665b79c..eb78fe8 100644
> --- a/crypto/af_alg.c
> +++ b/crypto/af_alg.c
> @@ -338,49 +338,31 @@ static const struct net_proto_family alg_family = {
> .owner = THIS_MODULE,
> };
>
> -int af_alg_make_sg(struct af_alg_sgl *sgl, void __user *addr, int len,
> - int write)
> +int af_alg_make_sg(struct af_alg_sgl *sgl, struct iov_iter *iter, int len)
Shouldn't len be size_t? iov_iter_get_pages wants a size_t. Also, the
invocation of af_alg_make_sg uses an unsigned variable that is provided by
userspace.
> {
> - unsigned long from = (unsigned long)addr;
> - unsigned long npages;
> - unsigned off;
> - int err;
> - int i;
> -
> - err = -EFAULT;
> - if (!access_ok(write ? VERIFY_READ : VERIFY_WRITE, addr, len))
> - goto out;
> -
> - off = from & ~PAGE_MASK;
> - npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
> - if (npages > ALG_MAX_PAGES)
> - npages = ALG_MAX_PAGES;
> + size_t off;
> + ssize_t n;
> + int npages, i;
>
> - err = get_user_pages_fast(from, npages, write, sgl->pages);
> - if (err < 0)
> - goto out;
> + n = iov_iter_get_pages(iter, sgl->pages, len, ALG_MAX_PAGES, &off);
> + if (n < 0)
> + return n;
>
> - npages = err;
> - err = -EINVAL;
> + npages = PAGE_ALIGN(off + n);
> if (WARN_ON(npages == 0))
> - goto out;
> -
> - err = 0;
> + return -EINVAL;
>
> sg_init_table(sgl->sg, npages);
>
> - for (i = 0; i < npages; i++) {
> + for (i = 0, len = n; i < npages; i++) {
> int plen = min_t(int, len, PAGE_SIZE - off);
>
> sg_set_page(sgl->sg + i, sgl->pages[i], plen, off);
>
> off = 0;
> len -= plen;
> - err += plen;
> }
> -
> -out:
> - return err;
> + return n;
> }
> EXPORT_SYMBOL_GPL(af_alg_make_sg);
>
> diff --git a/crypto/algif_hash.c b/crypto/algif_hash.c
> index 01f56eb..01da360 100644
> --- a/crypto/algif_hash.c
> +++ b/crypto/algif_hash.c
> @@ -41,8 +41,6 @@ static int hash_sendmsg(struct kiocb *unused, struct
> socket *sock, struct sock *sk = sock->sk;
> struct alg_sock *ask = alg_sk(sk);
> struct hash_ctx *ctx = ask->private;
> - unsigned long iovlen;
> - const struct iovec *iov;
> long copied = 0;
> int err;
>
> @@ -58,37 +56,28 @@ static int hash_sendmsg(struct kiocb *unused, struct
> socket *sock,
>
> ctx->more = 0;
>
> - for (iov = msg->msg_iter.iov, iovlen = msg->msg_iter.nr_segs; iovlen >
0;
> - iovlen--, iov++) {
> - unsigned long seglen = iov->iov_len;
> - char __user *from = iov->iov_base;
> + while (iov_iter_count(&msg->msg_iter)) {
> + int len = iov_iter_count(&msg->msg_iter);
size_t for len?
>
> - while (seglen) {
> - int len = min_t(unsigned long, seglen, limit);
> - int newlen;
> + if (len > limit)
> + len = limit;
If we leave int, do we have a wrap problem here?
>
> - newlen = af_alg_make_sg(&ctx->sgl, from, len, 0);
> - if (newlen < 0) {
> - err = copied ? 0 : newlen;
> - goto unlock;
> - }
> -
> - ahash_request_set_crypt(&ctx->req, ctx->sgl.sg, NULL,
> - newlen);
> -
> - err = af_alg_wait_for_completion(
> - crypto_ahash_update(&ctx->req),
> - &ctx->completion);
> + len = af_alg_make_sg(&ctx->sgl, &msg->msg_iter, len);
> + if (len < 0) {
> + err = copied ? 0 : len;
> + goto unlock;
> + }
>
> - af_alg_free_sg(&ctx->sgl);
> + ahash_request_set_crypt(&ctx->req, ctx->sgl.sg, NULL, len);
>
> - if (err)
> - goto unlock;
> + err = af_alg_wait_for_completion(crypto_ahash_update(&ctx-
>req),
> + &ctx->completion);
> + af_alg_free_sg(&ctx->sgl);
> + if (err)
> + goto unlock;
>
> - seglen -= newlen;
> - from += newlen;
> - copied += newlen;
> - }
> + copied += len;
> + iov_iter_advance(&msg->msg_iter, len);
> }
>
> err = 0;
> diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
> index c12207c..37110fd 100644
> --- a/crypto/algif_skcipher.c
> +++ b/crypto/algif_skcipher.c
> @@ -426,67 +426,59 @@ static int skcipher_recvmsg(struct kiocb *unused,
> struct socket *sock, &ctx->req));
> struct skcipher_sg_list *sgl;
> struct scatterlist *sg;
> - unsigned long iovlen;
> - const struct iovec *iov;
> int err = -EAGAIN;
> int used;
> long copied = 0;
>
> lock_sock(sk);
> - for (iov = msg->msg_iter.iov, iovlen = msg->msg_iter.nr_segs; iovlen >
0;
> - iovlen--, iov++) {
> - unsigned long seglen = iov->iov_len;
> - char __user *from = iov->iov_base;
> -
> - while (seglen) {
> - sgl = list_first_entry(&ctx->tsgl,
> - struct skcipher_sg_list, list);
> - sg = sgl->sg;
> -
> - while (!sg->length)
> - sg++;
> -
> - if (!ctx->used) {
> - err = skcipher_wait_for_data(sk, flags);
> - if (err)
> - goto unlock;
> - }
> + while (iov_iter_count(&msg->msg_iter)) {
> + sgl = list_first_entry(&ctx->tsgl,
> + struct skcipher_sg_list, list);
> + sg = sgl->sg;
>
> - used = min_t(unsigned long, ctx->used, seglen);
> + while (!sg->length)
> + sg++;
>
> - used = af_alg_make_sg(&ctx->rsgl, from, used, 1);
> - err = used;
> - if (err < 0)
> + used = ctx->used;
> + if (!used) {
I do not think that this change is correct. The following
skcipher_wait_for_data puts the recvmsg to sleep. That means, ctx->used may
change due to a new sendmsg() while sleeping.
Hence, I would think that we should leave the code as it was:
if (!ctx->used)
and then in the following
> + err = skcipher_wait_for_data(sk, flags);
> + if (err)
> goto unlock;
> + }
> +
> + used = min_t(unsigned long, used, iov_iter_count(&msg-
>msg_iter));
we use ctx->used here.
And shouldn't we use size_t here instead of unsigned long?
> +
> + used = af_alg_make_sg(&ctx->rsgl, &msg->msg_iter, used);
> + err = used;
> + if (err < 0)
> + goto unlock;
>
> - if (ctx->more || used < ctx->used)
> - used -= used % bs;
> + if (ctx->more || used < ctx->used)
> + used -= used % bs;
>
> - err = -EINVAL;
> - if (!used)
> - goto free;
> + err = -EINVAL;
> + if (!used)
> + goto free;
>
> - ablkcipher_request_set_crypt(&ctx->req, sg,
> - ctx->rsgl.sg, used,
> - ctx->iv);
> + ablkcipher_request_set_crypt(&ctx->req, sg,
> + ctx->rsgl.sg, used,
> + ctx->iv);
>
> - err = af_alg_wait_for_completion(
> + err = af_alg_wait_for_completion(
> ctx->enc ?
> crypto_ablkcipher_encrypt(&ctx->req) :
> crypto_ablkcipher_decrypt(&ctx->req),
> &ctx->completion);
>
> free:
> - af_alg_free_sg(&ctx->rsgl);
> + af_alg_free_sg(&ctx->rsgl);
>
> - if (err)
> - goto unlock;
> + if (err)
> + goto unlock;
>
> - copied += used;
> - from += used;
> - seglen -= used;
> - skcipher_pull_sgl(sk, used);
> - }
> + copied += used;
> + skcipher_pull_sgl(sk, used);
> + iov_iter_advance(&msg->msg_iter, used);
> }
>
> err = 0;
> diff --git a/include/crypto/if_alg.h b/include/crypto/if_alg.h
> index cd62bf4..88ea64e 100644
> --- a/include/crypto/if_alg.h
> +++ b/include/crypto/if_alg.h
> @@ -67,8 +67,7 @@ int af_alg_unregister_type(const struct af_alg_type
> *type); int af_alg_release(struct socket *sock);
> int af_alg_accept(struct sock *sk, struct socket *newsock);
>
> -int af_alg_make_sg(struct af_alg_sgl *sgl, void __user *addr, int len,
> - int write);
> +int af_alg_make_sg(struct af_alg_sgl *sgl, struct iov_iter *iter, int len);
> void af_alg_free_sg(struct af_alg_sgl *sgl);
>
> int af_alg_cmsg_send(struct msghdr *msg, struct af_alg_control *con);
--
Ciao
Stephan
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