On Fri, Sep 04, 2020 at 12:05:33PM -0400, Jeff Layton wrote:
> Allow ceph_mdsc_build_path to encrypt and base64 encode the filename
> when the parent is encrypted and we're sending the path to the MDS.
>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
> fs/ceph/mds_client.c | 51 ++++++++++++++++++++++++++++++++++----------
> 1 file changed, 40 insertions(+), 11 deletions(-)
>
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index e3dc061252d4..26b43ae09823 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -11,6 +11,7 @@
> #include <linux/ratelimit.h>
> #include <linux/bits.h>
> #include <linux/ktime.h>
> +#include <linux/base64_fname.h>
>
> #include "super.h"
> #include "mds_client.h"
> @@ -2324,8 +2325,7 @@ static inline u64 __get_oldest_tid(struct ceph_mds_client *mdsc)
> * Encode hidden .snap dirs as a double /, i.e.
> * foo/.snap/bar -> foo//bar
> */
> -char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *pbase,
> - int stop_on_nosnap)
> +char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *pbase, int for_wire)
> {
> struct dentry *cur;
> struct inode *inode;
> @@ -2347,30 +2347,59 @@ char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *pbase,
> seq = read_seqbegin(&rename_lock);
> cur = dget(dentry);
> for (;;) {
> - struct dentry *temp;
> + struct dentry *parent;
>
> spin_lock(&cur->d_lock);
> inode = d_inode(cur);
> + parent = cur->d_parent;
> if (inode && ceph_snap(inode) == CEPH_SNAPDIR) {
> dout("build_path path+%d: %p SNAPDIR\n",
> pos, cur);
> - } else if (stop_on_nosnap && inode && dentry != cur &&
> - ceph_snap(inode) == CEPH_NOSNAP) {
> + dget(parent);
> + spin_unlock(&cur->d_lock);
> + } else if (for_wire && inode && dentry != cur && ceph_snap(inode) == CEPH_NOSNAP) {
> spin_unlock(&cur->d_lock);
> pos++; /* get rid of any prepended '/' */
> break;
> - } else {
> + } else if (!for_wire || !IS_ENCRYPTED(d_inode(parent))) {
> pos -= cur->d_name.len;
> if (pos < 0) {
> spin_unlock(&cur->d_lock);
> break;
> }
> memcpy(path + pos, cur->d_name.name, cur->d_name.len);
> + dget(parent);
> + spin_unlock(&cur->d_lock);
> + } else {
> + int err;
> + struct fscrypt_name fname = { };
> + int len;
> + char buf[BASE64_CHARS(NAME_MAX)];
> +
> + dget(parent);
> + spin_unlock(&cur->d_lock);
> +
> + err = fscrypt_setup_filename(d_inode(parent), &cur->d_name, 1, &fname);
How are no-key filenames handled with ceph? You're calling
fscrypt_setup_filename() with lookup=1, so it will give you back a no-key
filename if the directory's encryption key is unavailable.
> + if (err) {
> + dput(parent);
> + dput(cur);
> + return ERR_PTR(err);
> + }
> +
> + /* base64 encode the encrypted name */
> + len = base64_encode_fname(fname.disk_name.name, fname.disk_name.len, buf);
> + pos -= len;
> + if (pos < 0) {
> + dput(parent);
> + fscrypt_free_filename(&fname);
> + break;
> + }
> + memcpy(path + pos, buf, len);
> + dout("non-ciphertext name = %.*s\n", len, buf);
> + fscrypt_free_filename(&fname);
This would be easier to understand if the encryption and encoding logic was
moved into its own function.
- Eric
