5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Pavel Begunkov <asml.silence@xxxxxxxxx>
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@xxxxxxxxxxxxxxx>
Fixes: 0091bfc81741b ("io_uring/af_unix: defer registered files gc to io_uring release")
Reported-and-suggested-by: Jann Horn <jannh@xxxxxxxxxx>
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Link: https://lore.kernel.org/r/c716c88321939156909cfa1bd8b0faaf1c804103.1701868795.git.asml.silence@xxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
@@ -8627,49 +8627,6 @@ 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)
{
@@ -8727,12 +8684,6 @@ 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)
@@ -8846,12 +8797,6 @@ 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++;
}
