Currently, if an application wants to duplicate registered file descriptors from one io_uring instance to another, it must manually unregister and re-register them, incurring unnecessary overhead.
Add IORING_REGISTER_CLONE_FILES to allow direct cloning of the file table from a source ring to a destination ring. This includes support for partial offsets and the IORING_REGISTER_DST_REPLACE flag. Signed-off-by: harshal24-chavan <[email protected]> --- v2: Dropped unrelated whitespace formatting changes from v1 --- include/uapi/linux/io_uring.h | 12 +++ io_uring/register.c | 6 ++ io_uring/rsrc.c | 160 ++++++++++++++++++++++++++++++++++ io_uring/rsrc.h | 1 + 4 files changed, 179 insertions(+) diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h index 909fb7aea638..0727602ce12f 100644 --- a/include/uapi/linux/io_uring.h +++ b/include/uapi/linux/io_uring.h @@ -723,6 +723,9 @@ enum io_uring_register_op { /* register bpf filtering programs */ IORING_REGISTER_BPF_FILTER = 37, + /* clone file descriptors from another ring*/ + IORING_REGISTER_CLONE_FILES = 38, + /* this goes last */ IORING_REGISTER_LAST, @@ -854,6 +857,15 @@ struct io_uring_clone_buffers { __u32 pad[3]; }; +struct io_uring_clone_files { + __u32 src_fd; + __u32 flags; + __u32 src_off; + __u32 dst_off; + __u32 nr; + __u32 pad[3]; +}; + struct io_uring_buf { __u64 addr; __u32 len; diff --git a/io_uring/register.c b/io_uring/register.c index dce5e2f9cf77..bbc8c506ea2d 100644 --- a/io_uring/register.c +++ b/io_uring/register.c @@ -924,6 +924,12 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode, break; ret = io_register_clone_buffers(ctx, arg); break; + case IORING_REGISTER_CLONE_FILES: + ret = -EINVAL; + if (!arg || nr_args != 1) + break; + ret = io_register_clone_files(ctx, arg); + break; case IORING_REGISTER_ZCRX_IFQ: ret = -EINVAL; if (!arg || nr_args != 1) diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c index 650303626be6..1e4e114ca5a5 100644 --- a/io_uring/rsrc.c +++ b/io_uring/rsrc.c @@ -1303,6 +1303,166 @@ int io_register_clone_buffers(struct io_ring_ctx *ctx, void __user *arg) return ret; } + +static int io_clone_files(struct io_ring_ctx *ctx, struct io_ring_ctx *src_ctx, + struct io_uring_clone_files *arg) +{ + struct io_file_table new_file_table; + int i, off, nr; + unsigned int src_nr; + + lockdep_assert_held(&ctx->uring_lock); + lockdep_assert_held(&src_ctx->uring_lock); + + /* if offsets are given, must have nr specified too */ + if (!arg->nr && (arg->dst_off || arg->src_off)) + return -EINVAL; + /* not allowed unless REPLACE is set */ + if (ctx->file_table.data.nr && + !(arg->flags & IORING_REGISTER_DST_REPLACE)) + return -EBUSY; + + src_nr = src_ctx->file_table.data.nr; + if (!src_nr) + return -ENXIO; + if (!arg->nr) + arg->nr = src_nr; + else if (arg->nr > src_nr) + return -EINVAL; + else if (arg->nr > IORING_MAX_FIXED_FILES) + return -EINVAL; + if (check_add_overflow(arg->nr, arg->src_off, &off) || off > src_nr) + return -EOVERFLOW; + if (check_add_overflow(arg->nr, arg->dst_off, &src_nr)) + return -EOVERFLOW; + if (src_nr > IORING_MAX_FIXED_FILES) + return -EINVAL; + /* Allocate file tables memory {data + bitmap} into new_file_table */ + memset(&new_file_table, 0, sizeof(new_file_table)); + if (!io_alloc_file_tables(ctx, &new_file_table, + max(src_nr, ctx->file_table.data.nr))) + return -ENOMEM; + + /* Copy original dst nodes from before the cloned range */ + for (i = 0; i < min(arg->dst_off, ctx->file_table.data.nr); i++) { + struct io_rsrc_node *node = ctx->file_table.data.nodes[i]; + + if (node) { + new_file_table.data.nodes[i] = node; + node->refs++; + io_file_bitmap_set(&new_file_table, i); + } + } + + off = arg->dst_off; + i = arg->src_off; + nr = arg->nr; + while (nr--) { + struct io_rsrc_node *dst_node, *src_node; + + src_node = io_rsrc_node_lookup(&src_ctx->file_table.data, i); + if (!src_node) { + dst_node = NULL; + } else { + dst_node = io_rsrc_node_alloc(ctx, IORING_RSRC_FILE); + if (!dst_node) { + io_free_file_tables(ctx, &new_file_table); + return -ENOMEM; + } + + struct file *file = io_slot_file(src_node); + + get_file(file); + io_fixed_file_set(dst_node, file); + } + new_file_table.data.nodes[off] = dst_node; + if (dst_node) + io_file_bitmap_set(&new_file_table, off); + + i++; + off++; + } + + /* Copy original dst nodes from after the cloned range */ + for (i = src_nr; i < ctx->file_table.data.nr; i++) { + struct io_rsrc_node *node = ctx->file_table.data.nodes[i]; + + if (node) { + new_file_table.data.nodes[i] = node; + node->refs++; + io_file_bitmap_set(&new_file_table, i); + } + } + + /* + * If asked for replace, put the old table. new_file_table.data->nodes[] holds both + * old and new nodes at this point. + */ + if (arg->flags & IORING_REGISTER_DST_REPLACE) + io_free_file_tables(ctx, &ctx->file_table); + + /* + * ctx->file_table must be empty now - either the contents are being + * replaced and we just freed the table, or the contents are being + * copied to a ring that does not have buffers yet (checked at function + * entry). + */ + WARN_ON_ONCE(ctx->file_table.data.nr); + ctx->file_table = new_file_table; + io_file_table_set_alloc_range(ctx, 0, ctx->file_table.data.nr); + return 0; +} + +int io_register_clone_files(struct io_ring_ctx *ctx, void __user *arg) +{ + struct io_uring_clone_files clone_arg; + struct io_ring_ctx *src_ctx; + bool registered_src; + struct file *file; + int ret; + + if (copy_from_user(&clone_arg, arg, sizeof(clone_arg))) + return -EFAULT; + if (clone_arg.flags & + ~(IORING_REGISTER_SRC_REGISTERED | IORING_REGISTER_DST_REPLACE)) + return -EINVAL; + /* not allowed unless REPLACE is set */ + if (!(clone_arg.flags & IORING_REGISTER_DST_REPLACE) && + ctx->file_table.data.nr) + return -EBUSY; + if (memchr_inv(clone_arg.pad, 0, sizeof(clone_arg.pad))) + return -EINVAL; + + registered_src = (clone_arg.flags & IORING_REGISTER_SRC_REGISTERED) != + 0; + file = io_uring_ctx_get_file(clone_arg.src_fd, registered_src); + if (IS_ERR(file)) + return PTR_ERR(file); + + src_ctx = file->private_data; + if (src_ctx != ctx) { + mutex_unlock(&ctx->uring_lock); + lock_two_rings(ctx, src_ctx); + + /* Prevent cross-process hijacking */ + if (src_ctx->submitter_task && + src_ctx->submitter_task != current) { + ret = -EEXIST; + goto out; + } + } + + ret = io_clone_files(ctx, src_ctx, &clone_arg); + +out: + if (src_ctx != ctx) + mutex_unlock(&src_ctx->uring_lock); + + if (!registered_src) + fput(file); + return ret; +} + void io_vec_free(struct iou_vec *iv) { if (!iv->iovec) diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h index 44e3386f7c1c..32f5c47c46af 100644 --- a/io_uring/rsrc.h +++ b/io_uring/rsrc.h @@ -75,6 +75,7 @@ int io_prep_reg_iovec(struct io_kiocb *req, struct iou_vec *iv, const struct iovec __user *uvec, size_t uvec_segs); int io_register_clone_buffers(struct io_ring_ctx *ctx, void __user *arg); +int io_register_clone_files(struct io_ring_ctx *ctx, void __user *arg); int io_sqe_buffers_unregister(struct io_ring_ctx *ctx); int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg, unsigned int nr_args, u64 __user *tags); -- 2.54.0
