5.10-stable review patch. If anyone has any objections, please let me know.
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From: Pavel Begunkov asml.silence@gmail.com
commit 705318a99a138c29a512a72c3e0043b3cd7f55f4 upstream.
File reference cycles have caused lots of problems for io_uring in the past, and it still doesn't work exactly right and races with unix_stream_read_generic(). The safest fix would be to completely disallow sending io_uring files via sockets via SCM_RIGHT, so there are no possible cycles invloving registered files and thus rendering SCM accounting on the io_uring side unnecessary.
Cc: stable@vger.kernel.org Fixes: 0091bfc81741b ("io_uring/af_unix: defer registered files gc to io_uring release") Reported-and-suggested-by: Jann Horn jannh@google.com Signed-off-by: Pavel Begunkov asml.silence@gmail.com Link: https://lore.kernel.org/r/c716c88321939156909cfa1bd8b0faaf1c804103.170186879... Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- io_uring/io_uring.c | 55 ---------------------------------------------------- net/core/scm.c | 6 +++++ 2 files changed, 6 insertions(+), 55 deletions(-)
--- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -8452,49 +8452,6 @@ out_free: return ret; }
-static int io_sqe_file_register(struct io_ring_ctx *ctx, struct file *file, - int index) -{ -#if defined(CONFIG_UNIX) - struct sock *sock = ctx->ring_sock->sk; - struct sk_buff_head *head = &sock->sk_receive_queue; - struct sk_buff *skb; - - /* - * See if we can merge this file into an existing skb SCM_RIGHTS - * file set. If there's no room, fall back to allocating a new skb - * and filling it in. - */ - spin_lock_irq(&head->lock); - skb = skb_peek(head); - if (skb) { - struct scm_fp_list *fpl = UNIXCB(skb).fp; - - if (fpl->count < SCM_MAX_FD) { - __skb_unlink(skb, head); - spin_unlock_irq(&head->lock); - fpl->fp[fpl->count] = get_file(file); - unix_inflight(fpl->user, fpl->fp[fpl->count]); - fpl->count++; - spin_lock_irq(&head->lock); - __skb_queue_head(head, skb); - } else { - skb = NULL; - } - } - spin_unlock_irq(&head->lock); - - if (skb) { - fput(file); - return 0; - } - - return __io_sqe_files_scm(ctx, 1, index); -#else - return 0; -#endif -} - static int io_queue_rsrc_removal(struct io_rsrc_data *data, unsigned idx, struct io_rsrc_node *node, void *rsrc) { @@ -8552,12 +8509,6 @@ static int io_install_fixed_file(struct
*io_get_tag_slot(ctx->file_data, slot_index) = 0; io_fixed_file_set(file_slot, file); - ret = io_sqe_file_register(ctx, file, slot_index); - if (ret) { - file_slot->file_ptr = 0; - goto err; - } - ret = 0; err: if (needs_switch) @@ -8671,12 +8622,6 @@ static int __io_sqe_files_update(struct } *io_get_tag_slot(data, i) = tag; io_fixed_file_set(file_slot, file); - err = io_sqe_file_register(ctx, file, i); - if (err) { - file_slot->file_ptr = 0; - fput(file); - break; - } } }
--- a/net/core/scm.c +++ b/net/core/scm.c @@ -26,6 +26,7 @@ #include <linux/nsproxy.h> #include <linux/slab.h> #include <linux/errqueue.h> +#include <linux/io_uring.h>
#include <linux/uaccess.h>
@@ -103,6 +104,11 @@ static int scm_fp_copy(struct cmsghdr *c
if (fd < 0 || !(file = fget_raw(fd))) return -EBADF; + /* don't allow io_uring files */ + if (io_uring_get_socket(file)) { + fput(file); + return -EINVAL; + } *fpp++ = file; fpl->count++; }