linux-kernel - Re: [RFC PATCH v2] ceph: allow encrypting a directory while not having Ax caps

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Date:   Mon, 7 Nov 2022 17:17:04 +0800
From:   Xiubo Li <xiubli@...hat.com>
To:     Luís Henriques <lhenriques@...e.de>,
        Ilya Dryomov <idryomov@...il.com>,
        Jeff Layton <jlayton@...nel.org>
Cc:     ceph-devel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v2] ceph: allow encrypting a directory while not
 having Ax caps


On 03/11/2022 22:06, Luís Henriques wrote:
> If a client doesn't have Fx caps on a directory, it will get errors while
> trying encrypt it:
>
> ceph: handle_cap_grant: cap grant attempt to change fscrypt_auth on non-I_NEW inode (old len 0 new len 48)
> fscrypt (ceph, inode 1099511627812): Error -105 getting encryption context
>
> A simple way to reproduce this is to use two clients:
>
>      client1 # mkdir /mnt/mydir
>
>      client2 # ls /mnt/mydir
>
>      client1 # fscrypt encrypt /mnt/mydir
>      client1 # echo hello > /mnt/mydir/world
>
> This happens because, in __ceph_setattr(), we only initialize
> ci->fscrypt_auth if we have Ax and ceph_fill_inode() won't use the
> fscrypt_auth received if the inode state isn't I_NEW.  Fix it by allowing
> ceph_fill_inode() to also set ci->fscrypt_auth if the inode doesn't have
> it set already.
>
> Signed-off-by: Luís Henriques <lhenriques@...e.de>
> ---
>   fs/ceph/inode.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
> index fb507d57cb26..c7831f801911 100644
> --- a/fs/ceph/inode.c
> +++ b/fs/ceph/inode.c
> @@ -1016,7 +1016,8 @@ int ceph_fill_inode(struct inode *inode, struct page *locked_page,
>   	__ceph_update_quota(ci, iinfo->max_bytes, iinfo->max_files);
>   
>   #ifdef CONFIG_FS_ENCRYPTION
> -	if (iinfo->fscrypt_auth_len && (inode->i_state & I_NEW)) {
> +	if (iinfo->fscrypt_auth_len &&
> +	    ((inode->i_state & I_NEW) || (ci->fscrypt_auth_len == 0))) {
>   		kfree(ci->fscrypt_auth);
>   		ci->fscrypt_auth_len = iinfo->fscrypt_auth_len;
>   		ci->fscrypt_auth = iinfo->fscrypt_auth;
>
Hi Luis,

This looks good to me.

I will test it and merge it if everything goes well.

Thanks!

- Xiubo