On Fri, Mar 21, 2025 at 05:32:25PM -0400, Paul Moore wrote:
> On Mar 21, 2025 Andrey Albershteyn <aalbe...@redhat.com> wrote:
> >
> > Introduce new hooks for setting and getting filesystem extended
> > attributes on inode (FS_IOC_FSGETXATTR).
> >
> > Cc: seli...@vger.kernel.org
> > Cc: Paul Moore <p...@paul-moore.com>
> >
> > Signed-off-by: Andrey Albershteyn <aalbe...@kernel.org>
> > ---
> > fs/ioctl.c | 7 ++++++-
> > include/linux/lsm_hook_defs.h | 4 ++++
> > include/linux/security.h | 16 ++++++++++++++++
> > security/security.c | 32 ++++++++++++++++++++++++++++++++
> > 4 files changed, 58 insertions(+), 1 deletion(-)
>
> Thanks Andrey, one small change below, but otherwise this looks pretty
> good. If you feel like trying to work up the SELinux implementation but
> need some assitance please let me know, I'll be happy to help :)
>
> > diff --git a/fs/ioctl.c b/fs/ioctl.c
> > index
> > 638a36be31c14afc66a7fd6eb237d9545e8ad997..4434c97bc5dff5a3e8635e28745cd99404ff353e
> > 100644
> > --- a/fs/ioctl.c
> > +++ b/fs/ioctl.c
> > @@ -525,10 +525,15 @@ EXPORT_SYMBOL(fileattr_fill_flags);
> > int vfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
> > {
> > struct inode *inode = d_inode(dentry);
> > + int error;
> >
> > if (!inode->i_op->fileattr_get)
> > return -ENOIOCTLCMD;
> >
> > + error = security_inode_getfsxattr(inode, fa);
> > + if (error)
> > + return error;
> > +
> > return inode->i_op->fileattr_get(dentry, fa);
> > }
> > EXPORT_SYMBOL(vfs_fileattr_get);
> > @@ -692,7 +697,7 @@ int vfs_fileattr_set(struct mnt_idmap *idmap, struct
> > dentry *dentry,
> > fa->flags |= old_ma.flags & ~FS_COMMON_FL;
> > }
> > err = fileattr_set_prepare(inode, &old_ma, fa);
> > - if (!err)
> > + if (!err && !security_inode_setfsxattr(inode, fa))
> > err = inode->i_op->fileattr_set(idmap, dentry, fa);
> > }
> > inode_unlock(inode);
>
> I don't believe we want to hide or otherwise drop the LSM return code as
> that could lead to odd behavior, e.g. returning 0/success despite not
> having executed the fileattr_set operation.
Yes, this should look something like this:
err = fileattr_set_prepare(inode, &old_ma, fa);
if (err)
goto out;
err = security_inode_setfsxattr(dentry, fa);
if (err)
goto out;
err = inode->i_op->fileattr_set(idmap, dentry, fa);
if (err)
goto out;
>
> --
> paul-moore.com
>
