Re: [PATCH 1/2] security: Handle dentries without inode in security_path_post_mknod()

[Roberto Sassu]

On 3/29/2024 4:05 PM, Mimi Zohar wrote:
> On Fri, 2024-03-29 at 11:56 +0100, Roberto Sassu wrote:
> > From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
> >
> > Commit 08abce60d63fi ("security: Introduce path_post_mknod hook")
> > introduced security_path_post_mknod(), to replace the IMA-specific call to
> > ima_post_path_mknod().
> >
> > For symmetry with security_path_mknod(), security_path_post_mknod() is
> > called after a successful mknod operation, for any file type, rather than
> > only for regular files at the time there was the IMA call.
> >
> > However, as reported by VFS maintainers, successful mknod operation does
> > not mean that the dentry always has an inode attached to it (for example,
> > not for FIFOs on a SAMBA mount).
> >
> > If that condition happens, the kernel crashes when
> > security_path_post_mknod() attempts to verify if the inode associated to
> > the dentry is private.
> >
> > Add an extra check to first verify if there is an inode attached to the
> > dentry, before checking if the inode is private. Also add the same check to
> > the current users of the path_post_mknod hook, ima_post_path_mknod() and
> > evm_post_path_mknod().
> >
> > Finally, use the proper helper, d_backing_inode(), to retrieve the inode
> > from the dentry in ima_post_path_mknod().
> >
> > Cc: stable@xxxxxxxxxxxxxxx # 6.8.x
>
> Huh?  It doesn't need to be backported.

Ehm, sorry. To be removed.

> > Reported-by: Steve French <smfrench@xxxxxxxxx>
> > Closes:
> > https://lore.kernel.org/linux-kernel/CAH2r5msAVzxCUHHG8VKrMPUKQHmBpE6K9_vjhgDa1uAvwx4ppw@xxxxxxxxxxxxxx/
> > Fixes: 08abce60d63fi ("security: Introduce path_post_mknod hook")
>
> -> 08abce60d63f

Ok.

Thanks

Roberto

> > Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
>
> Acked-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>