According to Documentation/driver-api/ioctl.rst, in order to support
32-bit user space running on a 64-bit kernel, each subsystem or driver
that implements an ioctl callback handler must also implement the
corresponding compat_ioctl handler. The compat_ptr_ioctl() helper can
be used in place of a custom compat_ioctl file operation for drivers
that only take arguments that are pointers to compatible data
structures.
In case of NS_* ioctls only NS_GET_OWNER_UID accepts an argument, and
this argument is a pointer to uid_t type, which is universally defined
to __kernel_uid32_t.
This change fixes compat strace --pidns-translation.
Note: when backporting this patch to stable kernels, commit
"compat_ioctl: add compat_ptr_ioctl()" is needed as well.
Reported-by: Ákos Uzonyi <uzonyi.akos@xxxxxxxxx>
Fixes: 6786741dbf99 ("nsfs: add ioctl to get an owning user namespace for ns file descriptor")
Cc: stable@xxxxxxxxxxxxxxx # v4.9+
Signed-off-by: Dmitry V. Levin <ldv@xxxxxxxxxxxx>
---
fs/nsfs.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/fs/nsfs.c b/fs/nsfs.c
index 800c1d0eb0d0..a00236bffa2c 100644
--- a/fs/nsfs.c
+++ b/fs/nsfs.c
@@ -21,6 +21,7 @@ static long ns_ioctl(struct file *filp, unsigned int ioctl,
static const struct file_operations ns_file_operations = {
.llseek = no_llseek,
.unlocked_ioctl = ns_ioctl,
+ .compat_ioctl = compat_ptr_ioctl,
};
static char *ns_dname(struct dentry *dentry, char *buffer, int buflen)
--
ldv
