crypto: switch af_alg_make_sg() to iov_iter

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@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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)
 {
-	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);
 

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);
 
-		while (seglen) {
-			int len = min_t(unsigned long, seglen, limit);
-			int newlen;
+		if (len > limit)
+			len = limit;
 
-			newlen = af_alg_make_sg(&ctx->sgl, from, len, 0);
-			if (newlen < 0) {
-				err = copied ? 0 : newlen;
+		len = af_alg_make_sg(&ctx->sgl, &msg->msg_iter, len);
+		if (len < 0) {
+			err = copied ? 0 : len;
 			goto unlock;
 		}
 
-			ahash_request_set_crypt(&ctx->req, ctx->sgl.sg, NULL,
-						newlen);
+		ahash_request_set_crypt(&ctx->req, ctx->sgl.sg, NULL, len);
 
-			err = af_alg_wait_for_completion(
-				crypto_ahash_update(&ctx->req),
+		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;

crypto/algif_skcipher.c

@@ -426,19 +426,12 @@ 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) {
+	while (iov_iter_count(&msg->msg_iter)) {
 		sgl = list_first_entry(&ctx->tsgl,
 				       struct skcipher_sg_list, list);
 		sg = sgl->sg;
@@ -446,15 +439,16 @@ static int skcipher_recvmsg(struct kiocb *unused, struct socket *sock,
 		while (!sg->length)
 			sg++;
 
-			if (!ctx->used) {
+		used = ctx->used;
+		if (!used) {
 			err = skcipher_wait_for_data(sk, flags);
 			if (err)
 				goto unlock;
 		}
 
-			used = min_t(unsigned long, ctx->used, seglen);
+		used = min_t(unsigned long, used, iov_iter_count(&msg->msg_iter));
 
-			used = af_alg_make_sg(&ctx->rsgl, from, used, 1);
+		used = af_alg_make_sg(&ctx->rsgl, &msg->msg_iter, used);
 		err = used;
 		if (err < 0)
 			goto unlock;
@@ -483,10 +477,8 @@ static int skcipher_recvmsg(struct kiocb *unused, struct socket *sock,
 			goto unlock;
 
 		copied += used;
-			from += used;
-			seglen -= used;
 		skcipher_pull_sgl(sk, used);
-		}
+		iov_iter_advance(&msg->msg_iter, used);
 	}
 
 	err = 0;

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);