On Fri, Sep 04, 2020 at 12:05:35PM -0400, Jeff Layton wrote:
> diff --git a/fs/ceph/crypto.h b/fs/ceph/crypto.h
> index 1b11e9af165e..88c672ccdcf8 100644
> --- a/fs/ceph/crypto.h
> +++ b/fs/ceph/crypto.h
> @@ -6,6 +6,8 @@
> #ifndef _CEPH_CRYPTO_H
> #define _CEPH_CRYPTO_H
>
> +#include <linux/fscrypt.h>
> +
> #ifdef CONFIG_FS_ENCRYPTION
>
> #define CEPH_XATTR_NAME_ENCRYPTION_CONTEXT "encryption.ctx"
> @@ -16,6 +18,29 @@ int ceph_fscrypt_set_ops(struct super_block *sb);
> int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inode,
> struct ceph_acl_sec_ctx *as);
>
> +static inline int ceph_fname_alloc_buffer(struct inode *parent, struct fscrypt_str *fname)
> +{
> + if (!IS_ENCRYPTED(parent))
> + return 0;
> + return fscrypt_fname_alloc_buffer(NAME_MAX, fname);
> +}
> +
> +static inline void ceph_fname_free_buffer(struct inode *parent, struct fscrypt_str *fname)
> +{
> + if (IS_ENCRYPTED(parent))
> + fscrypt_fname_free_buffer(fname);
> +}
> +
> +static inline int ceph_get_encryption_info(struct inode *inode)
> +{
> + if (!IS_ENCRYPTED(inode))
> + return 0;
> + return fscrypt_get_encryption_info(inode);
> +}
> +
> +int ceph_fname_to_usr(struct inode *parent, char *name, u32 len,
> + struct fscrypt_str *tname, struct fscrypt_str *oname);
> +
> #else /* CONFIG_FS_ENCRYPTION */
>
> #define DUMMY_ENCRYPTION_ENABLED(fsc) (0)
> @@ -31,6 +56,28 @@ static inline int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *
> return 0;
> }
>
> +static inline int ceph_fname_alloc_buffer(struct inode *parent, struct fscrypt_str *fname)
> +{
> + return 0;
> +}
> +
> +static inline void ceph_fname_free_buffer(struct inode *parent, struct fscrypt_str *fname)
> +{
> +}
> +
> +static inline int ceph_get_encryption_info(struct inode *inode)
> +{
> + return 0;
> +}
This makes it so that readdir will succeed on encrypted directories when
!CONFIG_FS_ENCRYPTION. The other filesystems instead return an error code,
which seems much better. Can you check what the other filesystems handle
readdir?
> +static bool fscrypt_key_status_change(struct dentry *dentry)
> +{
> + struct inode *dir;
> + bool encrypted_name, have_key;
> +
> + lockdep_assert_held(&dentry->d_lock);
> +
> + dir = d_inode(dentry->d_parent);
> + if (!IS_ENCRYPTED(dir))
> + return false;
> +
> + encrypted_name = dentry->d_flags & DCACHE_ENCRYPTED_NAME;
> + have_key = fscrypt_has_encryption_key(dir);
> +
> + if (encrypted_name == have_key)
> + ceph_dir_clear_complete(dir);
> +
> + dout("%s encrypted_name=%d have_key=%d\n", __func__, encrypted_name, have_key);
> + return encrypted_name == have_key;
> +}
> +
Only the no-key => key case needs to be handled, not key => no-key.
Also, the caller already has 'dir', so there's no need to use ->d_parent.
What's wrong with just:
di = ceph_dentry(dentry);
if (d_unhashed(dentry) ||
d_really_is_negative(dentry) ||
di->lease_shared_gen != shared_gen ||
+ ((dentry->d_flags & DCACHE_ENCRYPTED_NAME) &&
+ fscrypt_has_encryption_key(dir))) {
spin_unlock(&dentry->d_lock);
dput(dentry);
err = -EAGAIN;
goto out;
}
> /*
> * When possible, we try to satisfy a readdir by peeking at the
> * dcache. We make this work by carefully ordering dentries on
> @@ -238,11 +261,11 @@ static int __dcache_readdir(struct file *file, struct dir_context *ctx,
> goto out;
> }
>
> - spin_lock(&dentry->d_lock);
Why delete this spin_lock()?
> + if (IS_ENCRYPTED(inode) && !fscrypt_has_encryption_key(inode)) {
> + spin_lock(&dn->d_lock);
> + dn->d_flags |= DCACHE_ENCRYPTED_NAME;
> + spin_unlock(&dn->d_lock);
> + }
This is racy because fscrypt_has_encryption_key() could have been false when the
dentry was created, then true here.
Take a look at how __fscrypt_prepare_lookup() solves this problem.
- Eric
