Re: [PATCH 2/2] fuse: Send security context of inode on file creation

On Fri, Sep 24, 2021, at 3:24 PM, Vivek Goyal wrote:

When a new inode is created, send its security context to server along
with creation request (FUSE_CREAT, FUSE_MKNOD, FUSE_MKDIR and FUSE_SYMLINK).
This gives server an opportunity to create new file and set security
context (possibly atomically). In all the configurations it might not
be possible to set context atomically.

Like nfs and ceph, use security_dentry_init_security() to dermine security
context of inode and send it with create, mkdir, mknod, and symlink requests.

Following is the information sent to server.

- struct fuse_secctx.
  This contains total size of security context which follows this structure.

- xattr name string.
  This string represents name of xattr which should be used while setting
  security context. As of now it is hardcoded to "security.selinux".

Any reason not to just send all `security.*` xattrs found on the inode? 

(I'm not super familiar with this code, it looks like we're going from the LSM-cached version attached to the inode, but presumably since we're sending bytes we can just ask the filesytem for the raw data instead)