io_uring/rsrc: Drop io_copy_iov in favor of iovec API

Instead of open coding an io_uring function to copy iovs from userspace,
rely on the existing iovec_from_user function.  While there, avoid
repeatedly zeroing the iov in the !arg case for io_sqe_buffer_register.

tested with liburing testsuite.

Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
Link: https://lore.kernel.org/r/20240523214535.31890-1-krisman@suse.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index edb9c5baf2e29092fe65341b84a3b06c68a5d1af..e89c5e2326a25711313216539dfaa0da13477176 100644 (file)
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -85,31 +85,6 @@ static int io_account_mem(struct io_ring_ctx *ctx, unsigned long nr_pages)
        return 0;
 }
 
-static int io_copy_iov(struct io_ring_ctx *ctx, struct iovec *dst,
-                      void __user *arg, unsigned index)
-{
-       struct iovec __user *src;
-
-#ifdef CONFIG_COMPAT
-       if (ctx->compat) {
-               struct compat_iovec __user *ciovs;
-               struct compat_iovec ciov;
-
-               ciovs = (struct compat_iovec __user *) arg;
-               if (copy_from_user(&ciov, &ciovs[index], sizeof(ciov)))
-                       return -EFAULT;
-
-               dst->iov_base = u64_to_user_ptr((u64)ciov.iov_base);
-               dst->iov_len = ciov.iov_len;
-               return 0;
-       }
-#endif
-       src = (struct iovec __user *) arg;
-       if (copy_from_user(dst, &src[index], sizeof(*dst)))
-               return -EFAULT;
-       return 0;
-}
-
 static int io_buffer_validate(struct iovec *iov)
 {
        unsigned long tmp, acct_len = iov->iov_len + (PAGE_SIZE - 1);
@@ -420,8 +395,9 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
                                   struct io_uring_rsrc_update2 *up,
                                   unsigned int nr_args)
 {
+       struct iovec __user *uvec = u64_to_user_ptr(up->data);
        u64 __user *tags = u64_to_user_ptr(up->tags);
-       struct iovec iov, __user *iovs = u64_to_user_ptr(up->data);
+       struct iovec fast_iov, *iov;
        struct page *last_hpage = NULL;
        __u32 done;
        int i, err;
@@ -435,21 +411,23 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
                struct io_mapped_ubuf *imu;
                u64 tag = 0;
 
-               err = io_copy_iov(ctx, &iov, iovs, done);
-               if (err)
+               iov = iovec_from_user(&uvec[done], 1, 1, &fast_iov, ctx->compat);
+               if (IS_ERR(iov)) {
+                       err = PTR_ERR(iov);
                        break;
+               }
                if (tags && copy_from_user(&tag, &tags[done], sizeof(tag))) {
                        err = -EFAULT;
                        break;
                }
-               err = io_buffer_validate(&iov);
+               err = io_buffer_validate(iov);
                if (err)
                        break;
-               if (!iov.iov_base && tag) {
+               if (!iov->iov_base && tag) {
                        err = -EINVAL;
                        break;
                }
-               err = io_sqe_buffer_register(ctx, &iov, &imu, &last_hpage);
+               err = io_sqe_buffer_register(ctx, iov, &imu, &last_hpage);
                if (err)
                        break;
 
@@ -971,8 +949,9 @@ int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
 {
        struct page *last_hpage = NULL;
        struct io_rsrc_data *data;
+       struct iovec fast_iov, *iov = &fast_iov;
+       const struct iovec __user *uvec = (struct iovec * __user) arg;
        int i, ret;
-       struct iovec iov;
 
        BUILD_BUG_ON(IORING_MAX_REG_BUFFERS >= (1u << 16));
 
@@ -989,24 +968,27 @@ int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
                return ret;
        }
 
+       if (!arg)
+               memset(iov, 0, sizeof(*iov));
+
        for (i = 0; i < nr_args; i++, ctx->nr_user_bufs++) {
                if (arg) {
-                       ret = io_copy_iov(ctx, &iov, arg, i);
-                       if (ret)
+                       iov = iovec_from_user(&uvec[i], 1, 1, &fast_iov, ctx->compat);
+                       if (IS_ERR(iov)) {
+                               ret = PTR_ERR(iov);
                                break;
-                       ret = io_buffer_validate(&iov);
+                       }
+                       ret = io_buffer_validate(iov);
                        if (ret)
                                break;
-               } else {
-                       memset(&iov, 0, sizeof(iov));
                }
 
-               if (!iov.iov_base && *io_get_tag_slot(data, i)) {
+               if (!iov->iov_base && *io_get_tag_slot(data, i)) {
                        ret = -EINVAL;
                        break;
                }
 
-               ret = io_sqe_buffer_register(ctx, &iov, &ctx->user_bufs[i],
+               ret = io_sqe_buffer_register(ctx, iov, &ctx->user_bufs[i],
                                             &last_hpage);
                if (ret)
                        break;