From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- io_uring/splice.c | 149 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 149 insertions(+) create mode 100644 io_uring/splice.c (limited to 'io_uring/splice.c') diff --git a/io_uring/splice.c b/io_uring/splice.c new file mode 100644 index 000000000..e81ebbb91 --- /dev/null +++ b/io_uring/splice.c @@ -0,0 +1,149 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +#include "filetable.h" +#include "io_uring.h" +#include "splice.h" + +struct io_splice { + struct file *file_out; + loff_t off_out; + loff_t off_in; + u64 len; + int splice_fd_in; + unsigned int flags; + struct io_rsrc_node *rsrc_node; +}; + +static int __io_splice_prep(struct io_kiocb *req, + const struct io_uring_sqe *sqe) +{ + struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice); + unsigned int valid_flags = SPLICE_F_FD_IN_FIXED | SPLICE_F_ALL; + + sp->len = READ_ONCE(sqe->len); + sp->flags = READ_ONCE(sqe->splice_flags); + if (unlikely(sp->flags & ~valid_flags)) + return -EINVAL; + sp->splice_fd_in = READ_ONCE(sqe->splice_fd_in); + sp->rsrc_node = NULL; + req->flags |= REQ_F_FORCE_ASYNC; + return 0; +} + +int io_tee_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + if (READ_ONCE(sqe->splice_off_in) || READ_ONCE(sqe->off)) + return -EINVAL; + return __io_splice_prep(req, sqe); +} + +void io_splice_cleanup(struct io_kiocb *req) +{ + struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice); + + if (sp->rsrc_node) + io_put_rsrc_node(req->ctx, sp->rsrc_node); +} + +static struct file *io_splice_get_file(struct io_kiocb *req, + unsigned int issue_flags) +{ + struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice); + struct io_ring_ctx *ctx = req->ctx; + struct io_rsrc_node *node; + struct file *file = NULL; + + if (!(sp->flags & SPLICE_F_FD_IN_FIXED)) + return io_file_get_normal(req, sp->splice_fd_in); + + io_ring_submit_lock(ctx, issue_flags); + node = io_rsrc_node_lookup(&ctx->file_table.data, sp->splice_fd_in); + if (node) { + node->refs++; + sp->rsrc_node = node; + file = io_slot_file(node); + req->flags |= REQ_F_NEED_CLEANUP; + } + io_ring_submit_unlock(ctx, issue_flags); + return file; +} + +int io_tee(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice); + struct file *out = sp->file_out; + unsigned int flags = sp->flags & ~SPLICE_F_FD_IN_FIXED; + struct file *in; + ssize_t ret = 0; + + WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK); + + in = io_splice_get_file(req, issue_flags); + if (!in) { + ret = -EBADF; + goto done; + } + + if (sp->len) + ret = do_tee(in, out, sp->len, flags); + + if (!(sp->flags & SPLICE_F_FD_IN_FIXED)) + fput(in); +done: + if (ret != sp->len) + req_set_fail(req); + io_req_set_res(req, ret, 0); + return IOU_COMPLETE; +} + +int io_splice_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice); + + sp->off_in = READ_ONCE(sqe->splice_off_in); + sp->off_out = READ_ONCE(sqe->off); + return __io_splice_prep(req, sqe); +} + +int io_splice(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice); + struct file *out = sp->file_out; + unsigned int flags = sp->flags & ~SPLICE_F_FD_IN_FIXED; + loff_t *poff_in, *poff_out; + struct file *in; + ssize_t ret = 0; + + WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK); + + in = io_splice_get_file(req, issue_flags); + if (!in) { + ret = -EBADF; + goto done; + } + + poff_in = (sp->off_in == -1) ? NULL : &sp->off_in; + poff_out = (sp->off_out == -1) ? NULL : &sp->off_out; + + if (sp->len) + ret = do_splice(in, poff_in, out, poff_out, sp->len, flags); + + if (!(sp->flags & SPLICE_F_FD_IN_FIXED)) + fput(in); +done: + if (ret != sp->len) + req_set_fail(req); + io_req_set_res(req, ret, 0); + return IOU_COMPLETE; +} -- cgit v1.3.1