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Subject: Re: [PATCH v3] ceph: mark directory as non-complete complete after
 loading key
To:     =?UTF-8?Q?Lu=c3=ads_Henriques?= <lhenriques@suse.de>
Cc:     Ilya Dryomov <idryomov@gmail.com>,
        Jeff Layton <jlayton@kernel.org>, ceph-devel@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20221122145920.17025-1-lhenriques@suse.de>
 <e736d5ab-9876-187f-b24a-27461c09656b@redhat.com> <87ilj60z50.fsf@suse.de>
From:   Xiubo Li <xiubli@redhat.com>
Message-ID: <48fbac24-433c-9c4d-a251-95345cb289fa@redhat.com>
Date:   Wed, 23 Nov 2022 19:58:02 +0800
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On 23/11/2022 17:59, Luís Henriques wrote:
> Xiubo Li <xiubli@redhat.com> writes:
>
>> 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@suse.de>
>>> ---
>>> 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 ?
> No, that won't work, and I found that out the hard way :-)
>
> If the directory is unlocked (i.e. the key is loaded), then the helper
> function ceph_fscrypt_prepare_readdir() will return '0' because the status
> hasn't change.  Thus, we still need to check that here.

Yeah, sounds reasonable!

LGTM and I will run the test later!

Thanks Luis.

- Xiubo


> Cheers,