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SubjectRe: [PATCH v2] ceph: make sure directories aren't complete after setting crypt context
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On 22/11/2022 02:00, Luís Henriques wrote:
> When setting a directory's crypt context, __ceph_dir_clear_complete() needs
> to be used otherwise, if it was complete before, any old dentry that's still
> around will be valid.
>
> Signed-off-by: Luís Henriques <lhenriques@suse.de>
> ---
> Hi Xiubo!
>
> I've added the __fscrypt_prepare_readdir() wrapper as you suggested, but I
> had to change it slightly because we also need to handle the error cases.
>
> 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/dir.c | 31 ++++++++++++++++++++++++++++---
> 1 file changed, 28 insertions(+), 3 deletions(-)
>
> diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
> index edc2bf0aab83..2cac7e3ab352 100644
> --- a/fs/ceph/dir.c
> +++ b/fs/ceph/dir.c
> @@ -763,6 +763,27 @@ static bool is_root_ceph_dentry(struct inode *inode, struct dentry *dentry)
> strncmp(dentry->d_name.name, ".ceph", 5) == 0;
> }
>
> +/*
> + * Simple wrapper around __fscrypt_prepare_readdir() that will return:
> + *
> + * - '1' if directory was locked and key is now loaded (i.e. dir is unlocked),
> + * - '0' if directory is still locked, or
> + * - an error (< 0) if __fscrypt_prepare_readdir() fails.
> + */
> +static int ceph_fscrypt_prepare_readdir(struct inode *dir)
> +{
> + bool had_key = fscrypt_has_encryption_key(dir);
> + int err;
> +
> + err = __fscrypt_prepare_readdir(dir);
> + if (err)
> + return err;
> + /* is directory now unlocked? */
> + if (!had_key && fscrypt_has_encryption_key(dir))
> + return 1;
> + return 0;
> +}
> +
> /*
> * Look up a single dir entry. If there is a lookup intent, inform
> * the MDS so that it gets our 'caps wanted' value in a single op.
> @@ -784,10 +805,14 @@ 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)) {
> + if (err) {
> + /* directory just got unlocked */
> + __ceph_dir_clear_complete(ceph_inode(dir));

Luis,

Could we just move this into ceph_fscrypt_prepare_readdir() ? IMO we
should always clear the complete flag always whenever the key is first
loaded.

> + } else {
> + /* no encryption key */

I think you also need to fix all the other places, which are calling the
__fscrypt_prepare_readdir() or fscrypt_prepare_readdir() in ceph.
Because we don't know the ceph_lookup() will always be the first caller
to trigger __fscrypt_prepare_readdir() for a dir.

Thanks!

- Xiubo

> spin_lock(&dentry->d_lock);
> dentry->d_flags |= DCACHE_NOKEY_NAME;
> spin_unlock(&dentry->d_lock);
>

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