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

Luís Henriques
2022-11-23T10:10:40Z

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.

Cheers,
--
Luís