Re: [RFC PATCH v5 20/19] ceph: make ceph_get_name decrypt filenames

Jeff Layton
2021-04-01T18:03:39Z

On Thu, 2021-04-01 at 14:05 +0100, Luis Henriques wrote:
> On Thu, Apr 01, 2021 at 08:15:51AM -0400, Jeff Layton wrote:
> > On Thu, 2021-04-01 at 12:14 +0100, Luis Henriques wrote:
> > > On Wed, Mar 31, 2021 at 04:35:20PM -0400, Jeff Layton wrote:
> > > > When we do a lookupino to the MDS, we get a filename in the trace.
> > > > ceph_get_name uses that name directly, so we must properly decrypt
> > > > it before copying it to the name buffer.
> > > >
> > > > Signed-off-by: Jeff Layton <jlayton@kernel.org>
> > > > ---
> > > > fs/ceph/export.c | 42 +++++++++++++++++++++++++++++++-----------
> > > > 1 file changed, 31 insertions(+), 11 deletions(-)
> > > >
> > > > This patch is what's needed to fix the "busy inodes after umount"
> > > > issue I was seeing with xfstest generic/477, and also makes that
> > > > test pass reliably with mounts using -o test_dummy_encryption.
> > >
> > > You mentioned this issue the other day on IRC but I couldn't reproduce.
> > >
> > > On the other hand, I'm seeing another issue. Here's a way to reproduce:
> > >
> > > - create an encrypted dir 'd' and create a file 'f'
> > > - umount and mount the filesystem
> > > - unlock dir 'd'
> > > - cat d/f
> > > cat: d/2: No such file or directory
> >
> > I assume the message really says "cat: d/f: No such file or directory"
>
> Yes, of course :)
>
> > >
> > > It happens _almost_ every time I do the umount+mount+unlock+cat. Looks
> > > like ceph_atomic_open() fails to see that directory as encrypted. I don't
> > > think the problem is on this open itself, but in the unlock because a
> > > simple 'ls' also fails to show the decrypted names. (On the other end, if
> > > you do an 'ls' _before_ the unlock, everything seems to work fine.)
> > >
> > > I didn't had time to dig deeper into this yet, but I don't remember seeing
> > > this behaviour in previous versions of the patchset.
> > >
> > > Cheers,
> > > --
> > > Luís
> > >
> >
> > I've tried several times to reproduce this, but I haven't seen it happen
> > at all. It may be dependent on something in your environment (MDS
> > version, perhaps?). I'll try some more, but let me know if you track
> > down the cause.
>
> Hmm... it could be indeed. I'm running a vstart.sh cluster with pacific
> (HEAD in eb5d7a868c96 ("Merge PR #40473 into pacific")). It's trivial to
> reproduce here, so I now wonder if I'm really missing something on the MDS
> side. I had a disaster recently (a disk died) and I had to recreate my
> test environment. I don't think I had anything extra to run fscrypt
> tests, but I can't really remember.
>
> Anyway, I'll let you know if I get something.
>

Thanks. FWIW, I'm on a cephadm built cluster using a pacific(-ish) build
from about 2 weeks ago:

$ sudo ./cephadm version
Using recent ceph image docker.io/ceph/daemon-base@sha256:765d8c56160753aa4a92757a2e007f5821f8c0ec70b5fc998faf334a2b127df2
ceph version 17.0.0-1983-g6a19e303 (6a19e303187c2defceb9c785284ca401a4309c47) quincy (dev)

> Cheers,
> --
> Luís
>
>
> > Thanks,
> > Jeff
> >
> > > >
> > > > diff --git a/fs/ceph/export.c b/fs/ceph/export.c
> > > > index 17d8c8f4ec89..f4e3a17ffc01 100644
> > > > --- a/fs/ceph/export.c
> > > > +++ b/fs/ceph/export.c
> > > > @@ -7,6 +7,7 @@
> > > >
> > > > #include "super.h"
> > > > #include "mds_client.h"
> > > > +#include "crypto.h"
> > > >
> > > > /*
> > > > * Basic fh
> > > > @@ -516,7 +517,9 @@ static int ceph_get_name(struct dentry *parent, char *name,
> > > > {
> > > > struct ceph_mds_client *mdsc;
> > > > struct ceph_mds_request *req;
> > > > + struct inode *dir = d_inode(parent);
> > > > struct inode *inode = d_inode(child);
> > > > + struct ceph_mds_reply_info_parsed *rinfo;
> > > > int err;
> > > >
> > > > if (ceph_snap(inode) != CEPH_NOSNAP)
> > > > @@ -528,29 +531,46 @@ static int ceph_get_name(struct dentry *parent, char *name,
> > > > if (IS_ERR(req))
> > > > return PTR_ERR(req);
> > > >
> > > > - inode_lock(d_inode(parent));
> > > > -
> > > > + inode_lock(dir);
> > > > req->r_inode = inode;
> > > > ihold(inode);
> > > > req->r_ino2 = ceph_vino(d_inode(parent));
> > > > - req->r_parent = d_inode(parent);
> > > > + req->r_parent = dir;
> > > > set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
> > > > req->r_num_caps = 2;
> > > > err = ceph_mdsc_do_request(mdsc, NULL, req);
> > > > + inode_unlock(dir);
> > > >
> > > > - inode_unlock(d_inode(parent));
> > > > + if (err)
> > > > + goto out;
> > > >
> > > > - if (!err) {
> > > > - struct ceph_mds_reply_info_parsed *rinfo = &req->r_reply_info;
> > > > + rinfo = &req->r_reply_info;
> > > > + if (!IS_ENCRYPTED(dir)) {
> > > > memcpy(name, rinfo->dname, rinfo->dname_len);
> > > > name[rinfo->dname_len] = 0;
> > > > - dout("get_name %p ino %llx.%llx name %s\n",
> > > > - child, ceph_vinop(inode), name);
> > > > } else {
> > > > - dout("get_name %p ino %llx.%llx err %d\n",
> > > > - child, ceph_vinop(inode), err);
> > > > - }
> > > > + struct fscrypt_str oname = FSTR_INIT(NULL, 0);
> > > > + struct ceph_fname fname = { .dir = dir,
> > > > + .name = rinfo->dname,
> > > > + .ctext = rinfo->altname,
> > > > + .name_len = rinfo->dname_len,
> > > > + .ctext_len = rinfo->altname_len };
> > > > +
> > > > + err = ceph_fname_alloc_buffer(dir, &oname);
> > > > + if (err < 0)
> > > > + goto out;
> > > >
> > > > + err = ceph_fname_to_usr(&fname, NULL, &oname, NULL);
> > > > + if (!err) {
> > > > + memcpy(name, oname.name, oname.len);
> > > > + name[oname.len] = 0;
> > > > + }
> > > > + ceph_fname_free_buffer(dir, &oname);
> > > > + }
> > > > +out:
> > > > + dout("get_name %p ino %llx.%llx err %d %s%s\n",
> > > > + child, ceph_vinop(inode), err,
> > > > + err ? "" : "name ", err ? "" : name);
> > > > ceph_mdsc_put_request(req);
> > > > return err;
> > > > }
> > > > --
> > > > 2.30.2
> > > >
> >
> > --
> > Jeff Layton <jlayton@kernel.org>
> >
>

--
Jeff Layton <jlayton@kernel.org>