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>

3 files changed, 61 insertions, 98 deletions

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index 4665b79c729a..eb78fe8a60c8 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)
 {
-        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 01f56eb7816e..01da360bdb55 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);
 
-                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;
-                                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 c12207c8dde9..37110fd68adf 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) {
+                        err = skcipher_wait_for_data(sk, flags);
+                        if (err)
                                 goto unlock;
+                }
+
+                used = min_t(unsigned long, used, iov_iter_count(&msg->msg_iter));
+
+                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;