[PATCH 5.16 0929/1017] loop: fix ioctl calls using compat_loop_info

Greg Kroah-Hartman
2022-04-05T13:37:53Z

From: Carlos Llamas <cmllamas@google.com>

commit f941c51eeac7ebe0f8ec30943bf78e7f60aad039 upstream.

Support for cryptoloop was deleted in commit 47e9624616c8 ("block:
remove support for cryptoloop and the xor transfer"), making the usage
of loop_info->lo_encrypt_type obsolete. However, this member was also
removed from the compat_loop_info definition and this breaks userspace
ioctl calls for 32-bit binaries and CONFIG_COMPAT=y.

This patch restores the compat_loop_info->lo_encrypt_type member and
marks it obsolete as well as in the uapi header definitions.

Fixes: 47e9624616c8 ("block: remove support for cryptoloop and the xor transfer")
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220329201815.1347500-1-cmllamas@google.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/block/loop.c | 1 +
include/uapi/linux/loop.h | 4 ++--
2 files changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1603,6 +1603,7 @@ struct compat_loop_info {
compat_ulong_t lo_inode; /* ioctl r/o */
compat_dev_t lo_rdevice; /* ioctl r/o */
compat_int_t lo_offset;
+ compat_int_t lo_encrypt_type; /* obsolete, ignored */
compat_int_t lo_encrypt_key_size; /* ioctl w/o */
compat_int_t lo_flags; /* ioctl r/o */
char lo_name[LO_NAME_SIZE];
--- a/include/uapi/linux/loop.h
+++ b/include/uapi/linux/loop.h
@@ -45,7 +45,7 @@ struct loop_info {
unsigned long lo_inode; /* ioctl r/o */
__kernel_old_dev_t lo_rdevice; /* ioctl r/o */
int lo_offset;
- int lo_encrypt_type;
+ int lo_encrypt_type; /* obsolete, ignored */
int lo_encrypt_key_size; /* ioctl w/o */
int lo_flags;
char lo_name[LO_NAME_SIZE];
@@ -61,7 +61,7 @@ struct loop_info64 {
__u64 lo_offset;
__u64 lo_sizelimit;/* bytes, 0 == max available */
__u32 lo_number; /* ioctl r/o */
- __u32 lo_encrypt_type;
+ __u32 lo_encrypt_type; /* obsolete, ignored */
__u32 lo_encrypt_key_size; /* ioctl w/o */
__u32 lo_flags;
__u8 lo_file_name[LO_NAME_SIZE];