diff options
Diffstat (limited to 'io_uring/kbuf.c')
| -rw-r--r-- | io_uring/kbuf.c | 739 |
1 files changed, 739 insertions, 0 deletions
diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c new file mode 100644 index 000000000000..796d131107dd --- /dev/null +++ b/io_uring/kbuf.c @@ -0,0 +1,739 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/fs.h> +#include <linux/file.h> +#include <linux/mm.h> +#include <linux/slab.h> +#include <linux/namei.h> +#include <linux/poll.h> +#include <linux/vmalloc.h> +#include <linux/io_uring.h> + +#include <uapi/linux/io_uring.h> + +#include "io_uring.h" +#include "opdef.h" +#include "kbuf.h" +#include "memmap.h" + +/* BIDs are addressed by a 16-bit field in a CQE */ +#define MAX_BIDS_PER_BGID (1 << 16) + +/* Mapped buffer ring, return io_uring_buf from head */ +#define io_ring_head_to_buf(br, head, mask) &(br)->bufs[(head) & (mask)] + +struct io_provide_buf { + struct file *file; + __u64 addr; + __u32 len; + __u32 bgid; + __u32 nbufs; + __u16 bid; +}; + +static bool io_kbuf_inc_commit(struct io_buffer_list *bl, int len) +{ + while (len) { + struct io_uring_buf *buf; + u32 buf_len, this_len; + + buf = io_ring_head_to_buf(bl->buf_ring, bl->head, bl->mask); + buf_len = READ_ONCE(buf->len); + this_len = min_t(u32, len, buf_len); + buf_len -= this_len; + /* Stop looping for invalid buffer length of 0 */ + if (buf_len || !this_len) { + WRITE_ONCE(buf->addr, READ_ONCE(buf->addr) + this_len); + WRITE_ONCE(buf->len, buf_len); + return false; + } + WRITE_ONCE(buf->len, 0); + bl->head++; + len -= this_len; + } + return true; +} + +bool io_kbuf_commit(struct io_kiocb *req, + struct io_buffer_list *bl, int len, int nr) +{ + if (unlikely(!(req->flags & REQ_F_BUFFERS_COMMIT))) + return true; + + req->flags &= ~REQ_F_BUFFERS_COMMIT; + + if (unlikely(len < 0)) + return true; + if (bl->flags & IOBL_INC) + return io_kbuf_inc_commit(bl, len); + bl->head += nr; + return true; +} + +static inline struct io_buffer_list *io_buffer_get_list(struct io_ring_ctx *ctx, + unsigned int bgid) +{ + lockdep_assert_held(&ctx->uring_lock); + + return xa_load(&ctx->io_bl_xa, bgid); +} + +static int io_buffer_add_list(struct io_ring_ctx *ctx, + struct io_buffer_list *bl, unsigned int bgid) +{ + /* + * Store buffer group ID and finally mark the list as visible. + * The normal lookup doesn't care about the visibility as we're + * always under the ->uring_lock, but lookups from mmap do. + */ + bl->bgid = bgid; + guard(mutex)(&ctx->mmap_lock); + return xa_err(xa_store(&ctx->io_bl_xa, bgid, bl, GFP_KERNEL)); +} + +void io_kbuf_drop_legacy(struct io_kiocb *req) +{ + if (WARN_ON_ONCE(!(req->flags & REQ_F_BUFFER_SELECTED))) + return; + req->flags &= ~REQ_F_BUFFER_SELECTED; + kfree(req->kbuf); + req->kbuf = NULL; +} + +bool io_kbuf_recycle_legacy(struct io_kiocb *req, unsigned issue_flags) +{ + struct io_ring_ctx *ctx = req->ctx; + struct io_buffer_list *bl; + struct io_buffer *buf; + + io_ring_submit_lock(ctx, issue_flags); + + buf = req->kbuf; + bl = io_buffer_get_list(ctx, buf->bgid); + list_add(&buf->list, &bl->buf_list); + bl->nbufs++; + req->flags &= ~REQ_F_BUFFER_SELECTED; + + io_ring_submit_unlock(ctx, issue_flags); + return true; +} + +static void __user *io_provided_buffer_select(struct io_kiocb *req, size_t *len, + struct io_buffer_list *bl) +{ + if (!list_empty(&bl->buf_list)) { + struct io_buffer *kbuf; + + kbuf = list_first_entry(&bl->buf_list, struct io_buffer, list); + list_del(&kbuf->list); + bl->nbufs--; + if (*len == 0 || *len > kbuf->len) + *len = kbuf->len; + if (list_empty(&bl->buf_list)) + req->flags |= REQ_F_BL_EMPTY; + req->flags |= REQ_F_BUFFER_SELECTED; + req->kbuf = kbuf; + req->buf_index = kbuf->bid; + return u64_to_user_ptr(kbuf->addr); + } + return NULL; +} + +static int io_provided_buffers_select(struct io_kiocb *req, size_t *len, + struct io_buffer_list *bl, + struct iovec *iov) +{ + void __user *buf; + + buf = io_provided_buffer_select(req, len, bl); + if (unlikely(!buf)) + return -ENOBUFS; + + iov[0].iov_base = buf; + iov[0].iov_len = *len; + return 1; +} + +static bool io_should_commit(struct io_kiocb *req, unsigned int issue_flags) +{ + /* + * If we came in unlocked, we have no choice but to consume the + * buffer here, otherwise nothing ensures that the buffer won't + * get used by others. This does mean it'll be pinned until the + * IO completes, coming in unlocked means we're being called from + * io-wq context and there may be further retries in async hybrid + * mode. For the locked case, the caller must call commit when + * the transfer completes (or if we get -EAGAIN and must poll of + * retry). + */ + if (issue_flags & IO_URING_F_UNLOCKED) + return true; + + /* uring_cmd commits kbuf upfront, no need to auto-commit */ + if (!io_file_can_poll(req) && req->opcode != IORING_OP_URING_CMD) + return true; + return false; +} + +static struct io_br_sel io_ring_buffer_select(struct io_kiocb *req, size_t *len, + struct io_buffer_list *bl, + unsigned int issue_flags) +{ + struct io_uring_buf_ring *br = bl->buf_ring; + __u16 tail, head = bl->head; + struct io_br_sel sel = { }; + struct io_uring_buf *buf; + u32 buf_len; + + tail = smp_load_acquire(&br->tail); + if (unlikely(tail == head)) + return sel; + + if (head + 1 == tail) + req->flags |= REQ_F_BL_EMPTY; + + buf = io_ring_head_to_buf(br, head, bl->mask); + buf_len = READ_ONCE(buf->len); + if (*len == 0 || *len > buf_len) + *len = buf_len; + req->flags |= REQ_F_BUFFER_RING | REQ_F_BUFFERS_COMMIT; + req->buf_index = READ_ONCE(buf->bid); + sel.buf_list = bl; + sel.addr = u64_to_user_ptr(READ_ONCE(buf->addr)); + + if (io_should_commit(req, issue_flags)) { + io_kbuf_commit(req, sel.buf_list, *len, 1); + sel.buf_list = NULL; + } + return sel; +} + +struct io_br_sel io_buffer_select(struct io_kiocb *req, size_t *len, + unsigned buf_group, unsigned int issue_flags) +{ + struct io_ring_ctx *ctx = req->ctx; + struct io_br_sel sel = { }; + struct io_buffer_list *bl; + + io_ring_submit_lock(req->ctx, issue_flags); + + bl = io_buffer_get_list(ctx, buf_group); + if (likely(bl)) { + if (bl->flags & IOBL_BUF_RING) + sel = io_ring_buffer_select(req, len, bl, issue_flags); + else + sel.addr = io_provided_buffer_select(req, len, bl); + } + io_ring_submit_unlock(req->ctx, issue_flags); + return sel; +} + +/* cap it at a reasonable 256, will be one page even for 4K */ +#define PEEK_MAX_IMPORT 256 + +static int io_ring_buffers_peek(struct io_kiocb *req, struct buf_sel_arg *arg, + struct io_buffer_list *bl) +{ + struct io_uring_buf_ring *br = bl->buf_ring; + struct iovec *iov = arg->iovs; + int nr_iovs = arg->nr_iovs; + __u16 nr_avail, tail, head; + struct io_uring_buf *buf; + + tail = smp_load_acquire(&br->tail); + head = bl->head; + nr_avail = min_t(__u16, tail - head, UIO_MAXIOV); + if (unlikely(!nr_avail)) + return -ENOBUFS; + + buf = io_ring_head_to_buf(br, head, bl->mask); + if (arg->max_len) { + u32 len = READ_ONCE(buf->len); + size_t needed; + + if (unlikely(!len)) + return -ENOBUFS; + needed = (arg->max_len + len - 1) / len; + needed = min_not_zero(needed, (size_t) PEEK_MAX_IMPORT); + if (nr_avail > needed) + nr_avail = needed; + } + + /* + * only alloc a bigger array if we know we have data to map, eg not + * a speculative peek operation. + */ + if (arg->mode & KBUF_MODE_EXPAND && nr_avail > nr_iovs && arg->max_len) { + iov = kmalloc_array(nr_avail, sizeof(struct iovec), GFP_KERNEL); + if (unlikely(!iov)) + return -ENOMEM; + if (arg->mode & KBUF_MODE_FREE) + kfree(arg->iovs); + arg->iovs = iov; + nr_iovs = nr_avail; + } else if (nr_avail < nr_iovs) { + nr_iovs = nr_avail; + } + + /* set it to max, if not set, so we can use it unconditionally */ + if (!arg->max_len) + arg->max_len = INT_MAX; + + req->buf_index = READ_ONCE(buf->bid); + do { + u32 len = READ_ONCE(buf->len); + + /* truncate end piece, if needed, for non partial buffers */ + if (len > arg->max_len) { + len = arg->max_len; + if (!(bl->flags & IOBL_INC)) { + arg->partial_map = 1; + if (iov != arg->iovs) + break; + WRITE_ONCE(buf->len, len); + } + } + + iov->iov_base = u64_to_user_ptr(READ_ONCE(buf->addr)); + iov->iov_len = len; + iov++; + + arg->out_len += len; + arg->max_len -= len; + if (!arg->max_len) + break; + + buf = io_ring_head_to_buf(br, ++head, bl->mask); + } while (--nr_iovs); + + if (head == tail) + req->flags |= REQ_F_BL_EMPTY; + + req->flags |= REQ_F_BUFFER_RING; + return iov - arg->iovs; +} + +int io_buffers_select(struct io_kiocb *req, struct buf_sel_arg *arg, + struct io_br_sel *sel, unsigned int issue_flags) +{ + struct io_ring_ctx *ctx = req->ctx; + int ret = -ENOENT; + + io_ring_submit_lock(ctx, issue_flags); + sel->buf_list = io_buffer_get_list(ctx, arg->buf_group); + if (unlikely(!sel->buf_list)) + goto out_unlock; + + if (sel->buf_list->flags & IOBL_BUF_RING) { + ret = io_ring_buffers_peek(req, arg, sel->buf_list); + /* + * Don't recycle these buffers if we need to go through poll. + * Nobody else can use them anyway, and holding on to provided + * buffers for a send/write operation would happen on the app + * side anyway with normal buffers. Besides, we already + * committed them, they cannot be put back in the queue. + */ + if (ret > 0) { + req->flags |= REQ_F_BUFFERS_COMMIT | REQ_F_BL_NO_RECYCLE; + io_kbuf_commit(req, sel->buf_list, arg->out_len, ret); + } + } else { + ret = io_provided_buffers_select(req, &arg->out_len, sel->buf_list, arg->iovs); + } +out_unlock: + if (issue_flags & IO_URING_F_UNLOCKED) { + sel->buf_list = NULL; + mutex_unlock(&ctx->uring_lock); + } + return ret; +} + +int io_buffers_peek(struct io_kiocb *req, struct buf_sel_arg *arg, + struct io_br_sel *sel) +{ + struct io_ring_ctx *ctx = req->ctx; + struct io_buffer_list *bl; + int ret; + + lockdep_assert_held(&ctx->uring_lock); + + bl = io_buffer_get_list(ctx, arg->buf_group); + if (unlikely(!bl)) + return -ENOENT; + + if (bl->flags & IOBL_BUF_RING) { + ret = io_ring_buffers_peek(req, arg, bl); + if (ret > 0) + req->flags |= REQ_F_BUFFERS_COMMIT; + sel->buf_list = bl; + return ret; + } + + /* don't support multiple buffer selections for legacy */ + sel->buf_list = NULL; + return io_provided_buffers_select(req, &arg->max_len, bl, arg->iovs); +} + +static inline bool __io_put_kbuf_ring(struct io_kiocb *req, + struct io_buffer_list *bl, int len, int nr) +{ + bool ret = true; + + if (bl) + ret = io_kbuf_commit(req, bl, len, nr); + + req->flags &= ~REQ_F_BUFFER_RING; + return ret; +} + +unsigned int __io_put_kbufs(struct io_kiocb *req, struct io_buffer_list *bl, + int len, int nbufs) +{ + unsigned int ret; + + ret = IORING_CQE_F_BUFFER | (req->buf_index << IORING_CQE_BUFFER_SHIFT); + + if (unlikely(!(req->flags & REQ_F_BUFFER_RING))) { + io_kbuf_drop_legacy(req); + return ret; + } + + if (!__io_put_kbuf_ring(req, bl, len, nbufs)) + ret |= IORING_CQE_F_BUF_MORE; + return ret; +} + +static int io_remove_buffers_legacy(struct io_ring_ctx *ctx, + struct io_buffer_list *bl, + unsigned long nbufs) +{ + unsigned long i = 0; + struct io_buffer *nxt; + + /* protects io_buffers_cache */ + lockdep_assert_held(&ctx->uring_lock); + WARN_ON_ONCE(bl->flags & IOBL_BUF_RING); + + for (i = 0; i < nbufs && !list_empty(&bl->buf_list); i++) { + nxt = list_first_entry(&bl->buf_list, struct io_buffer, list); + list_del(&nxt->list); + bl->nbufs--; + kfree(nxt); + cond_resched(); + } + return i; +} + +static void io_put_bl(struct io_ring_ctx *ctx, struct io_buffer_list *bl) +{ + if (bl->flags & IOBL_BUF_RING) + io_free_region(ctx->user, &bl->region); + else + io_remove_buffers_legacy(ctx, bl, -1U); + + kfree(bl); +} + +void io_destroy_buffers(struct io_ring_ctx *ctx) +{ + struct io_buffer_list *bl; + + while (1) { + unsigned long index = 0; + + scoped_guard(mutex, &ctx->mmap_lock) { + bl = xa_find(&ctx->io_bl_xa, &index, ULONG_MAX, XA_PRESENT); + if (bl) + xa_erase(&ctx->io_bl_xa, bl->bgid); + } + if (!bl) + break; + io_put_bl(ctx, bl); + } +} + +static void io_destroy_bl(struct io_ring_ctx *ctx, struct io_buffer_list *bl) +{ + scoped_guard(mutex, &ctx->mmap_lock) + WARN_ON_ONCE(xa_erase(&ctx->io_bl_xa, bl->bgid) != bl); + io_put_bl(ctx, bl); +} + +int io_remove_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf); + u64 tmp; + + if (sqe->rw_flags || sqe->addr || sqe->len || sqe->off || + sqe->splice_fd_in) + return -EINVAL; + + tmp = READ_ONCE(sqe->fd); + if (!tmp || tmp > MAX_BIDS_PER_BGID) + return -EINVAL; + + memset(p, 0, sizeof(*p)); + p->nbufs = tmp; + p->bgid = READ_ONCE(sqe->buf_group); + return 0; +} + +int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + unsigned long size, tmp_check; + struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf); + u64 tmp; + + if (sqe->rw_flags || sqe->splice_fd_in) + return -EINVAL; + + tmp = READ_ONCE(sqe->fd); + if (!tmp || tmp > MAX_BIDS_PER_BGID) + return -E2BIG; + p->nbufs = tmp; + p->addr = READ_ONCE(sqe->addr); + p->len = READ_ONCE(sqe->len); + if (!p->len) + return -EINVAL; + + if (check_mul_overflow((unsigned long)p->len, (unsigned long)p->nbufs, + &size)) + return -EOVERFLOW; + if (check_add_overflow((unsigned long)p->addr, size, &tmp_check)) + return -EOVERFLOW; + if (!access_ok(u64_to_user_ptr(p->addr), size)) + return -EFAULT; + + p->bgid = READ_ONCE(sqe->buf_group); + tmp = READ_ONCE(sqe->off); + if (tmp > USHRT_MAX) + return -E2BIG; + if (tmp + p->nbufs > MAX_BIDS_PER_BGID) + return -EINVAL; + p->bid = tmp; + return 0; +} + +static int io_add_buffers(struct io_ring_ctx *ctx, struct io_provide_buf *pbuf, + struct io_buffer_list *bl) +{ + struct io_buffer *buf; + u64 addr = pbuf->addr; + int ret = -ENOMEM, i, bid = pbuf->bid; + + for (i = 0; i < pbuf->nbufs; i++) { + /* + * Nonsensical to have more than sizeof(bid) buffers in a + * buffer list, as the application then has no way of knowing + * which duplicate bid refers to what buffer. + */ + if (bl->nbufs == USHRT_MAX) { + ret = -EOVERFLOW; + break; + } + buf = kmalloc(sizeof(*buf), GFP_KERNEL_ACCOUNT); + if (!buf) + break; + + list_add_tail(&buf->list, &bl->buf_list); + bl->nbufs++; + buf->addr = addr; + buf->len = min_t(__u32, pbuf->len, MAX_RW_COUNT); + buf->bid = bid; + buf->bgid = pbuf->bgid; + addr += pbuf->len; + bid++; + cond_resched(); + } + + return i ? 0 : ret; +} + +static int __io_manage_buffers_legacy(struct io_kiocb *req, + struct io_buffer_list *bl) +{ + struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf); + int ret; + + if (!bl) { + if (req->opcode != IORING_OP_PROVIDE_BUFFERS) + return -ENOENT; + bl = kzalloc(sizeof(*bl), GFP_KERNEL_ACCOUNT); + if (!bl) + return -ENOMEM; + + INIT_LIST_HEAD(&bl->buf_list); + ret = io_buffer_add_list(req->ctx, bl, p->bgid); + if (ret) { + kfree(bl); + return ret; + } + } + /* can't use provide/remove buffers command on mapped buffers */ + if (bl->flags & IOBL_BUF_RING) + return -EINVAL; + if (req->opcode == IORING_OP_PROVIDE_BUFFERS) + return io_add_buffers(req->ctx, p, bl); + return io_remove_buffers_legacy(req->ctx, bl, p->nbufs); +} + +int io_manage_buffers_legacy(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf); + struct io_ring_ctx *ctx = req->ctx; + struct io_buffer_list *bl; + int ret; + + io_ring_submit_lock(ctx, issue_flags); + bl = io_buffer_get_list(ctx, p->bgid); + ret = __io_manage_buffers_legacy(req, bl); + io_ring_submit_unlock(ctx, issue_flags); + + if (ret < 0) + req_set_fail(req); + io_req_set_res(req, ret, 0); + return IOU_COMPLETE; +} + +int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg) +{ + struct io_uring_buf_reg reg; + struct io_buffer_list *bl; + struct io_uring_region_desc rd; + struct io_uring_buf_ring *br; + unsigned long mmap_offset; + unsigned long ring_size; + int ret; + + lockdep_assert_held(&ctx->uring_lock); + + if (copy_from_user(®, arg, sizeof(reg))) + return -EFAULT; + if (!mem_is_zero(reg.resv, sizeof(reg.resv))) + return -EINVAL; + if (reg.flags & ~(IOU_PBUF_RING_MMAP | IOU_PBUF_RING_INC)) + return -EINVAL; + if (!is_power_of_2(reg.ring_entries)) + return -EINVAL; + /* cannot disambiguate full vs empty due to head/tail size */ + if (reg.ring_entries >= 65536) + return -EINVAL; + + bl = io_buffer_get_list(ctx, reg.bgid); + if (bl) { + /* if mapped buffer ring OR classic exists, don't allow */ + if (bl->flags & IOBL_BUF_RING || !list_empty(&bl->buf_list)) + return -EEXIST; + io_destroy_bl(ctx, bl); + } + + bl = kzalloc(sizeof(*bl), GFP_KERNEL_ACCOUNT); + if (!bl) + return -ENOMEM; + + mmap_offset = (unsigned long)reg.bgid << IORING_OFF_PBUF_SHIFT; + ring_size = flex_array_size(br, bufs, reg.ring_entries); + + memset(&rd, 0, sizeof(rd)); + rd.size = PAGE_ALIGN(ring_size); + if (!(reg.flags & IOU_PBUF_RING_MMAP)) { + rd.user_addr = reg.ring_addr; + rd.flags |= IORING_MEM_REGION_TYPE_USER; + } + ret = io_create_region(ctx, &bl->region, &rd, mmap_offset); + if (ret) + goto fail; + br = io_region_get_ptr(&bl->region); + +#ifdef SHM_COLOUR + /* + * On platforms that have specific aliasing requirements, SHM_COLOUR + * is set and we must guarantee that the kernel and user side align + * nicely. We cannot do that if IOU_PBUF_RING_MMAP isn't set and + * the application mmap's the provided ring buffer. Fail the request + * if we, by chance, don't end up with aligned addresses. The app + * should use IOU_PBUF_RING_MMAP instead, and liburing will handle + * this transparently. + */ + if (!(reg.flags & IOU_PBUF_RING_MMAP) && + ((reg.ring_addr | (unsigned long)br) & (SHM_COLOUR - 1))) { + ret = -EINVAL; + goto fail; + } +#endif + + bl->nr_entries = reg.ring_entries; + bl->mask = reg.ring_entries - 1; + bl->flags |= IOBL_BUF_RING; + bl->buf_ring = br; + if (reg.flags & IOU_PBUF_RING_INC) + bl->flags |= IOBL_INC; + io_buffer_add_list(ctx, bl, reg.bgid); + return 0; +fail: + io_free_region(ctx->user, &bl->region); + kfree(bl); + return ret; +} + +int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg) +{ + struct io_uring_buf_reg reg; + struct io_buffer_list *bl; + + lockdep_assert_held(&ctx->uring_lock); + + if (copy_from_user(®, arg, sizeof(reg))) + return -EFAULT; + if (!mem_is_zero(reg.resv, sizeof(reg.resv)) || reg.flags) + return -EINVAL; + + bl = io_buffer_get_list(ctx, reg.bgid); + if (!bl) + return -ENOENT; + if (!(bl->flags & IOBL_BUF_RING)) + return -EINVAL; + + scoped_guard(mutex, &ctx->mmap_lock) + xa_erase(&ctx->io_bl_xa, bl->bgid); + + io_put_bl(ctx, bl); + return 0; +} + +int io_register_pbuf_status(struct io_ring_ctx *ctx, void __user *arg) +{ + struct io_uring_buf_status buf_status; + struct io_buffer_list *bl; + + if (copy_from_user(&buf_status, arg, sizeof(buf_status))) + return -EFAULT; + if (!mem_is_zero(buf_status.resv, sizeof(buf_status.resv))) + return -EINVAL; + + bl = io_buffer_get_list(ctx, buf_status.buf_group); + if (!bl) + return -ENOENT; + if (!(bl->flags & IOBL_BUF_RING)) + return -EINVAL; + + buf_status.head = bl->head; + if (copy_to_user(arg, &buf_status, sizeof(buf_status))) + return -EFAULT; + + return 0; +} + +struct io_mapped_region *io_pbuf_get_region(struct io_ring_ctx *ctx, + unsigned int bgid) +{ + struct io_buffer_list *bl; + + lockdep_assert_held(&ctx->mmap_lock); + + bl = xa_load(&ctx->io_bl_xa, bgid); + if (!bl || !(bl->flags & IOBL_BUF_RING)) + return NULL; + return &bl->region; +} |