On Sun, Jul 09, 2023 at 02:53:38PM -0400, Sweet Tea Dorminy wrote:
> For extent-based encryption, leaf/regular file inodes are special: it's
> useful to set their i_crypt_info field so that it's easy to inherit
> their encryption policy for a new extent, but they never need to do any
> encyption themselves. Additionally, since encryption can only be set up
> on a directory, not a single file, their encryption policy can always
> duplicate their parent inode's policy.
>
> Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@xxxxxxxxxx>
> ---
> fs/crypto/fscrypt_private.h | 17 +++++++++++++
> fs/crypto/keysetup.c | 49 ++++++++++++++++++++++++++-----------
> 2 files changed, 52 insertions(+), 14 deletions(-)
>
> diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
> index c04454c289fd..260635e8b558 100644
> --- a/fs/crypto/fscrypt_private.h
> +++ b/fs/crypto/fscrypt_private.h
> @@ -308,6 +308,23 @@ fscrypt_get_lblk_info(const struct inode *inode, u64 lblk, u64 *offset,
> return inode->i_crypt_info;
> }
>
> +/**
> + * fscrypt_uses_extent_encryption() -- whether an inode uses per-extent
> + * encryption
> + *
> + * @inode: the inode in question
> + *
> + * Return: true if the inode uses per-extent fscrypt_infos, false otherwise
> + */
> +static inline bool fscrypt_uses_extent_encryption(const struct inode *inode)
> +{
> + // Non-regular files don't have extents
> + if (!S_ISREG(inode->i_mode))
> + return false;
> +
> + // No filesystems currently use per-extent infos
> + return false;
Wrong comment format.
> +}
>
> /* crypto.c */
> extern struct kmem_cache *fscrypt_info_cachep;
> diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
> index c5f68cf65a6f..7469b2d8ac87 100644
> --- a/fs/crypto/keysetup.c
> +++ b/fs/crypto/keysetup.c
> @@ -747,27 +747,48 @@ fscrypt_setup_encryption_info(struct inode *inode,
> int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported)
> {
> int res;
> - union fscrypt_context ctx;
> + union fscrypt_context ctx = { 0 };
> union fscrypt_policy policy;
>
> if (fscrypt_has_encryption_key(inode))
> return 0;
>
> - res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
> - if (res < 0) {
> - if (res == -ERANGE && allow_unsupported)
> - return 0;
> - fscrypt_warn(inode, "Error %d getting encryption context", res);
> - return res;
> - }
> + if (fscrypt_uses_extent_encryption(inode)) {
> + /*
> + * Nothing will be encrypted with this info, so we can borrow
> + * the parent (dir) inode's policy and use a zero nonce.
> + */
> + struct dentry *dentry = d_find_any_alias(inode);
> + struct dentry *parent_dentry = dget_parent(dentry);
> + struct inode *dir = parent_dentry->d_inode;
> + bool found = false;
>
Can this be extracted to a helper to keep this function cleaner? Thanks,
Josef
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