Jeff Layton <jlayton@xxxxxxxxxx> writes:
> On Thu, 2022-02-24 at 11:21 +0000, Luís Henriques wrote:
>> Since filenames in encrypted directories are already encrypted and shown
>> as a base64-encoded string when the directory is locked, snapshot names
>> should show a similar behaviour.
>>
>> Signed-off-by: Luís Henriques <lhenriques@xxxxxxx>
>> ---
>> fs/ceph/dir.c | 15 +++++++++++++++
>> fs/ceph/inode.c | 10 +++++++++-
>> 2 files changed, 24 insertions(+), 1 deletion(-)
>>
>> Support on the MDS for names that'll be > MAX_NAME when base64 encoded is
>> still TBD. I thought it would be something easy to do, but snapshots
>> don't seem to make use of the CDir/CDentry (which is where alternate_name
>> is stored on the MDS). I'm still looking into this, but I may need some
>> help there :-(
>>
>> Cheers,
>> --
>> Luís
>>
>> diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
>> index a449f4a07c07..20ae600ee7cd 100644
>> --- a/fs/ceph/dir.c
>> +++ b/fs/ceph/dir.c
>> @@ -1065,6 +1065,13 @@ static int ceph_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
>> op = CEPH_MDS_OP_MKSNAP;
>> dout("mksnap dir %p snap '%pd' dn %p\n", dir,
>> dentry, dentry);
>> + /* XXX missing support for alternate_name in snapshots */
>> + if (IS_ENCRYPTED(dir) && (dentry->d_name.len >= 189)) {
>> + dout("encrypted snapshot name too long: %pd len: %d\n",
>> + dentry, dentry->d_name.len);
>> + err = -ENAMETOOLONG;
>> + goto out;
>> + }
>
> Where does 189 come from? You probably want to use CEPH_NOHASH_NAME_MAX.
>
Yeah, this is just a temporary workaround while the support for altnames
isn't implemented in snapshots. (189 is the max size that will result in
a base64-encoded that is < MAX_NAME; 190 will be result in a filename that
is too long).
>> } else if (ceph_snap(dir) == CEPH_NOSNAP) {
>> dout("mkdir dir %p dn %p mode 0%ho\n", dir, dentry, mode);
>> op = CEPH_MDS_OP_MKDIR;
>> @@ -1109,6 +1116,14 @@ static int ceph_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
>> !req->r_reply_info.head->is_target &&
>> !req->r_reply_info.head->is_dentry)
>> err = ceph_handle_notrace_create(dir, dentry);
>> +
>> + /*
>> + * If we have created a snapshot we need to clear the cache, otherwise
>> + * snapshot will show encrypted filenames in readdir.
>> + */
>> + if (ceph_snap(dir) == CEPH_SNAPDIR)
>> + d_drop(dentry);
>> +
>
> This looks hacky, but I just caught up on the discussion between you and
> Xiubo, so I assume you're addressing that.
Right, I still need to investigate this further. It may actually be a bug
somewhere else. Right now I was trying to get the MDS code written and
decided to look at this later. I just thought I could send out this RFC
anyway in case someone had an idea -- and Xiubo already gave some
suggestions (which I still have to look at...).
>
>> out_req:
>> ceph_mdsc_put_request(req);
>> out:
>> diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
>> index 8b0832271fdf..080824610b73 100644
>> --- a/fs/ceph/inode.c
>> +++ b/fs/ceph/inode.c
>> @@ -182,6 +182,13 @@ struct inode *ceph_get_snapdir(struct inode *parent)
>> ci->i_rbytes = 0;
>> ci->i_btime = ceph_inode(parent)->i_btime;
>>
>> + /* if encrypted, just borough fscrypt_auth from parent */
>> + if (IS_ENCRYPTED(parent)) {
>> + struct ceph_inode_info *pci = ceph_inode(parent);
>> + inode->i_flags |= S_ENCRYPTED;
>> + ci->fscrypt_auth_len = pci->fscrypt_auth_len;
>> + ci->fscrypt_auth = pci->fscrypt_auth;
>> + }
>> if (inode->i_state & I_NEW) {
>> inode->i_op = &ceph_snapdir_iops;
>> inode->i_fop = &ceph_snapdir_fops;
>> @@ -632,7 +639,8 @@ void ceph_free_inode(struct inode *inode)
>>
>> kfree(ci->i_symlink);
>> #ifdef CONFIG_FS_ENCRYPTION
>> - kfree(ci->fscrypt_auth);
>> + if (ceph_snap(inode) != CEPH_SNAPDIR)
>> + kfree(ci->fscrypt_auth);
>
> Can a snapdir inode outlive its parent?
Good question. That actually occurred to me and I assumed it can not.
But maybe a better/safer option is to create a new copy of fscrypt_auth
into the snapdir and kfree it here.
Cheers,
--
Luís
>
>> #endif
>> fscrypt_free_inode(inode);
>> kmem_cache_free(ceph_inode_cachep, ci);
>
> --
> Jeff Layton <jlayton@xxxxxxxxxx>
