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Subject[RFC PATCH] ceph: add support for encrypted snapshot names
Date
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@suse.de>
---
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;
+ }
} 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);
+
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);
#endif
fscrypt_free_inode(inode);
kmem_cache_free(ceph_inode_cachep, ci);
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