[PATCH 01/32] pidfs: validate extensible ioctls

[Christian Brauner]

Validate extensible ioctls stricter than we do now.

Signed-off-by: Christian Brauner <brau...@kernel.org>
---
 fs/pidfs.c         |  2 +-
 include/linux/fs.h | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/fs/pidfs.c b/fs/pidfs.c
index edc35522d75c..0a5083b9cce5 100644
--- a/fs/pidfs.c
+++ b/fs/pidfs.c
@@ -440,7 +440,7 @@ static bool pidfs_ioctl_valid(unsigned int cmd)
                 * erronously mistook the file descriptor for a pidfd.
                 * This is not perfect but will catch most cases.
                 */
-               return (_IOC_TYPE(cmd) == _IOC_TYPE(PIDFD_GET_INFO));
+               return extensible_ioctl_valid(cmd, PIDFD_GET_INFO, 
PIDFD_INFO_SIZE_VER0);
        }
 
        return false;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index d7ab4f96d705..2f2edc53bf3c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -4023,4 +4023,18 @@ static inline bool vfs_empty_path(int dfd, const char 
__user *path)
 
 int generic_atomic_write_valid(struct kiocb *iocb, struct iov_iter *iter);
 
+static inline bool extensible_ioctl_valid(unsigned int cmd_a,
+                                         unsigned int cmd_b, size_t min_size)
+{
+       if (_IOC_DIR(cmd_a) != _IOC_DIR(cmd_b))
+               return false;
+       if (_IOC_TYPE(cmd_a) != _IOC_TYPE(cmd_b))
+               return false;
+       if (_IOC_NR(cmd_a) != _IOC_NR(cmd_b))
+               return false;
+       if (_IOC_SIZE(cmd_a) < min_size)
+               return false;
+       return true;
+}
+
 #endif /* _LINUX_FS_H */

-- 
2.47.3