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io_uring/af_unix: disable sending io_uring over sockets

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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/c716c88321939156909cfa1bd8b0faaf1c804103.1701868795.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Pavel Begunkov 2023-12-06 13:26:47 +00:00 • committed by Ksawlii
parent 191edae40a
commit b74b88ed25
2 changed files with 6 additions and 55 deletions
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55
io_uring/io_uring.c
View file

@ -8462,49 +8462,6 @@ out_free:
return ret; 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, static int io_queue_rsrc_removal(struct io_rsrc_data *data, unsigned idx,
struct io_rsrc_node *node, void *rsrc) struct io_rsrc_node *node, void *rsrc)
{ {
@ -8562,12 +8519,6 @@ static int io_install_fixed_file(struct io_kiocb *req, struct file *file,
*io_get_tag_slot(ctx->file_data, slot_index) = 0; *io_get_tag_slot(ctx->file_data, slot_index) = 0;
io_fixed_file_set(file_slot, file); 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; ret = 0;
err: err:
if (needs_switch) if (needs_switch)
@ -8681,12 +8632,6 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
} }
*io_get_tag_slot(data, i) = tag; *io_get_tag_slot(data, i) = tag;
io_fixed_file_set(file_slot, file); 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;
}
} }
} }

6
net/core/scm.c
View file

@ -26,6 +26,7 @@
#include <linux/nsproxy.h> #include <linux/nsproxy.h>
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/errqueue.h> #include <linux/errqueue.h>
#include <linux/io_uring.h>
#include <linux/uaccess.h> #include <linux/uaccess.h>
@ -103,6 +104,11 @@ static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
if (fd < 0 || !(file = fget_raw(fd))) if (fd < 0 || !(file = fget_raw(fd)))
return -EBADF; return -EBADF;
/* don't allow io_uring files */
if (io_uring_get_socket(file)) {
fput(file);
return -EINVAL;
}
*fpp++ = file; *fpp++ = file;
fpl->count++; fpl->count++;
} }