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[SRU,L/M,1/1] io_uring/af_unix: disable sending io_uring over sockets

Message ID 20240103220940.55576-2-yuxuan.luo@canonical.com
State New
Headers show
Series CVE-2023-6531 | expand

Commit Message

Yuxuan Luo Jan. 3, 2024, 10:09 p.m. UTC 
From: Pavel Begunkov <asml.silence@gmail.com>

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>
(cherry picked from commit 705318a99a138c29a512a72c3e0043b3cd7f55f4)
CVE-2023-6531
Signed-off-by: Yuxuan Luo <yuxuan.luo@canonical.com>
---
 io_uring/rsrc.h | 7 -------
 net/core/scm.c  | 6 ++++++
 2 files changed, 6 insertions(+), 7 deletions(-)
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Patch

diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index 8625181fb87ac..08ac0d8e07ef8 100644
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -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);
 
-#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 880027ecf5165..7dc47c17d8638 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 @@  static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
 
 		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++;
 	}