Re: [PATCH v3] ceph: mark directory as non-complete complete after loading key

[Xiubo Li]

On 22/11/2022 22:59, Luís Henriques wrote:
> When setting a directory's crypt context, ceph_dir_clear_complete() needs to
> be called otherwise if it was complete before, any existing (old) dentry will
> still be valid.
>
> This patch adds a wrapper around __fscrypt_prepare_readdir() which will
> ensure a directory is marked as non-complete if key status changes.
>
> Signed-off-by: Luís Henriques <lhenriques@xxxxxxx>
> ---
> Hi!
>
> Hopefully I'm not breaking anything else.  I've run a bunch of fstests and
> didn't saw any (new) failures.
>
> Changes since v2:
> - Created helper wrapper for __fscrypt_prepare_readdir()
> - Added calls to the new helper
>
> Changes since v1:
> - Moved the __ceph_dir_clear_complete() call from ceph_crypt_get_context()
>    to ceph_lookup().
> - Added an __fscrypt_prepare_readdir() wrapper to check key status changes
>
>   fs/ceph/crypto.c     | 35 +++++++++++++++++++++++++++++++++--
>   fs/ceph/crypto.h     |  6 ++++++
>   fs/ceph/dir.c        |  8 ++++----
>   fs/ceph/mds_client.c |  6 +++---
>   4 files changed, 46 insertions(+), 9 deletions(-)
>
> diff --git a/fs/ceph/crypto.c b/fs/ceph/crypto.c
> index 35a2ccfe6899..5ef65a06af98 100644
> --- a/fs/ceph/crypto.c
> +++ b/fs/ceph/crypto.c
> @@ -397,8 +397,8 @@ int ceph_fname_to_usr(const struct ceph_fname *fname, struct fscrypt_str *tname,
>   		goto out_inode;
>   	}
>   
> -	ret = __fscrypt_prepare_readdir(dir);
> -	if (ret)
> +	ret = ceph_fscrypt_prepare_readdir(dir);
> +	if (ret < 0)
>   		goto out_inode;
>   
>   	/*
> @@ -636,3 +636,34 @@ int ceph_fscrypt_encrypt_pages(struct inode *inode, struct page **page, u64 off,
>   	}
>   	return ret;
>   }
> +
> +/**
> + * ceph_fscrypt_prepare_readdir - simple __fscrypt_prepare_readdir() wrapper
> + * @dir: directory inode for readdir prep
> + *
> + * Simple wrapper around __fscrypt_prepare_readdir() that will mark directory as
> + * non-complete if this call results in having the directory unlocked.
> + *
> + * Returns:
> + *     1 - if directory was locked and key is now loaded (i.e. dir is unlocked)
> + *     0 - if directory is still locked
> + *   < 0 - if __fscrypt_prepare_readdir() fails
> + */
> +int ceph_fscrypt_prepare_readdir(struct inode *dir)
> +{
> +	bool had_key = fscrypt_has_encryption_key(dir);
> +	int err;
> +
> +	if (!IS_ENCRYPTED(dir))
> +		return 0;
> +
> +	err = __fscrypt_prepare_readdir(dir);
> +	if (err)
> +		return err;
> +	if (!had_key && fscrypt_has_encryption_key(dir)) {
> +		/* directory just got unlocked, mark it as not complete */
> +		ceph_dir_clear_complete(dir);
> +		return 1;
> +	}
> +	return 0;
> +}
> diff --git a/fs/ceph/crypto.h b/fs/ceph/crypto.h
> index c6ee993f4ec8..cad53ec916fd 100644
> --- a/fs/ceph/crypto.h
> +++ b/fs/ceph/crypto.h
> @@ -154,6 +154,7 @@ int ceph_fscrypt_decrypt_extents(struct inode *inode, struct page **page, u64 of
>   				 struct ceph_sparse_extent *map, u32 ext_cnt);
>   int ceph_fscrypt_encrypt_pages(struct inode *inode, struct page **page, u64 off,
>   				int len, gfp_t gfp);
> +int ceph_fscrypt_prepare_readdir(struct inode *dir);
>   
>   static inline struct page *ceph_fscrypt_pagecache_page(struct page *page)
>   {
> @@ -254,6 +255,11 @@ static inline struct page *ceph_fscrypt_pagecache_page(struct page *page)
>   {
>   	return page;
>   }
> +
> +static inline int ceph_fscrypt_prepare_readdir(struct inode *dir)
> +{
> +	return 0;
> +}
>   #endif /* CONFIG_FS_ENCRYPTION */
>   
>   static inline loff_t ceph_fscrypt_page_offset(struct page *page)
> diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
> index edc2bf0aab83..5829f27d058d 100644
> --- a/fs/ceph/dir.c
> +++ b/fs/ceph/dir.c
> @@ -343,8 +343,8 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
>   		ctx->pos = 2;
>   	}
>   
> -	err = fscrypt_prepare_readdir(inode);
> -	if (err)
> +	err = ceph_fscrypt_prepare_readdir(inode);
> +	if (err < 0)
>   		return err;
>   
>   	spin_lock(&ci->i_ceph_lock);
> @@ -784,8 +784,8 @@ static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry,
>   		return ERR_PTR(-ENAMETOOLONG);
>   
>   	if (IS_ENCRYPTED(dir)) {
> -		err = __fscrypt_prepare_readdir(dir);
> -		if (err)
> +		err = ceph_fscrypt_prepare_readdir(dir);
> +		if (err < 0)
>   			return ERR_PTR(err);
>   		if (!fscrypt_has_encryption_key(dir)) {
>   			spin_lock(&dentry->d_lock);
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index 9518ac8e407d..4becc9eada4b 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -2551,8 +2551,8 @@ static u8 *get_fscrypt_altname(const struct ceph_mds_request *req, u32 *plen)
>   	if (!IS_ENCRYPTED(dir))
>   		goto success;
>   
> -	ret = __fscrypt_prepare_readdir(dir);
> -	if (ret)
> +	ret = ceph_fscrypt_prepare_readdir(dir);
> +	if (ret < 0)
>   		return ERR_PTR(ret);
>   
>   	/* No key? Just ignore it. */
> @@ -2668,7 +2668,7 @@ char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *pbase, int for
>   			spin_unlock(&cur->d_lock);
>   			parent = dget_parent(cur);
>   
> -			ret = __fscrypt_prepare_readdir(d_inode(parent));
> +			ret = ceph_fscrypt_prepare_readdir(d_inode(parent));
>   			if (ret < 0) {
>   				dput(parent);
>   				dput(cur);

Hi Luis,

This version LGTM.

Just one nit. I think the following:

if (fscrypt_has_encryption_key(d_inode(parent))) {

is no needed any more.

We can just switch to:

if (ret) {

And also other places ?

Thanks!

- Xiubo

>