io_uring/af_unix: disable sending io_uring over sockets
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.
BUG=b/322957888
TEST=presubmit
RELEASE_NOTE=Fixed CVE-2023-6531 in the Linux kernel.
Fixes: 0091bfc81741b ("io_uring/af_unix: defer registered files gc to io_uring release")
Reported-and-suggested-by: Jann Horn <jannh@google.com>
Change-Id: I602e976415f448dc6cb09dc58f09389f64af7a62
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>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/64352
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Michael Kochera <kochera@google.com>
diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index d60c758..acaf8da 100644
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -79,17 +79,10 @@
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)
{
return false;
}
-#endif
static inline int io_scm_file_account(struct io_ring_ctx *ctx,
struct file *file)
diff --git a/net/core/scm.c b/net/core/scm.c
index acb7d77..e762a4b 100644
--- 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 @@
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++;
}
