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io_uring/af_unix: disable sending io_uring over sockets

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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: 0091bfc817 ("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>
This commit is contained in:
Pavel Begunkov 2023-12-06 13:26:47 +00:00 committed by Jens Axboe
parent 9865346b7e
commit 705318a99a
2 changed files with 6 additions and 7 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

7
io_uring/rsrc.h
View file

@ -77,17 +77,10 @@ int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
int __io_scm_file_account(struct io_ring_ctx *ctx, struct file *file); int __io_scm_file_account(struct io_ring_ctx *ctx, struct file *file);
#if defined(CONFIG_UNIX)
static inline bool io_file_need_scm(struct file *filp)
{
return !!unix_get_socket(filp);
}
#else
static inline bool io_file_need_scm(struct file *filp) static inline bool io_file_need_scm(struct file *filp)
{ {
return false; return false;
} }
#endif
static inline int io_scm_file_account(struct io_ring_ctx *ctx, static inline int io_scm_file_account(struct io_ring_ctx *ctx,
struct file *file) struct file *file)

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++;
} }