On Tue, Aug 08, 2023 at 01:08:24PM -0400, Sweet Tea Dorminy wrote:
> Since per-extent infos are not tied to inodes, an ino-based policy
> cannot access the inode's i_ino to get the necessary information.
> Instead, this adds an optional fscrypt_operation pointer to get the ino
> equivalent for an extent, adds a wrapper to get the ino for an info, and
> uses this wrapper everywhere where the ci's inode's i_ino is currently
> accessed.
>
> Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@xxxxxxxxxx>
> ---
> fs/crypto/fscrypt_private.h | 18 ++++++++++++++++++
> fs/crypto/keyring.c | 8 ++++----
> fs/crypto/keysetup.c | 6 +++---
> include/linux/fscrypt.h | 9 +++++++++
> 4 files changed, 34 insertions(+), 7 deletions(-)
>
> diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
> index 1244797cd8a9..4fe79b774f1f 100644
> --- a/fs/crypto/fscrypt_private.h
> +++ b/fs/crypto/fscrypt_private.h
> @@ -332,6 +332,24 @@ static inline bool fscrypt_uses_extent_encryption(const struct inode *inode)
> return false;
> }
>
> +/**
> + * fscrypt_get_info_ino() - get the ino or ino equivalent for an info
> + *
> + * @ci: the fscrypt_info in question
> + *
> + * Return: For inode-based encryption, this will return the info's inode's ino.
> + * For extent-based encryption, this will return the extent's ino equivalent
> + * or 0 if it is not implemented.
> + */
> +static inline u64 fscrypt_get_info_ino(const struct fscrypt_info *ci)
> +{
> + if (ci->ci_inode)
> + return ci->ci_inode->i_ino;
> + if (!ci->ci_sb->s_cop->get_extent_ino_equivalent)
> + return 0;
> + return ci->ci_sb->s_cop->get_extent_ino_equivalent(ci->ci_info_ptr);
> +}
> +
> /* crypto.c */
> extern struct kmem_cache *fscrypt_info_cachep;
> int fscrypt_initialize(struct super_block *sb);
> diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c
> index 7cbb1fd872ac..53e37b8a822c 100644
> --- a/fs/crypto/keyring.c
> +++ b/fs/crypto/keyring.c
> @@ -914,12 +914,12 @@ static int check_for_busy_inodes(struct super_block *sb,
> }
>
> {
> - /* select an example file to show for debugging purposes */
> - struct inode *inode =
> + /* select an example info to show for debugging purposes */
> + struct fscrypt_info *ci =
> list_first_entry(&mk->mk_decrypted_inodes,
> struct fscrypt_info,
> - ci_master_key_link)->ci_inode;
> - ino = inode->i_ino;
> + ci_master_key_link);
> + ino = fscrypt_get_info_ino(ci);
> }
> spin_unlock(&mk->mk_decrypted_inodes_lock);
>
> diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
> index c72f9015ed35..32e62cc57708 100644
> --- a/fs/crypto/keysetup.c
> +++ b/fs/crypto/keysetup.c
> @@ -380,10 +380,10 @@ int fscrypt_derive_dirhash_key(struct fscrypt_info *ci,
> void fscrypt_hash_inode_number(struct fscrypt_info *ci,
> const struct fscrypt_master_key *mk)
> {
> - WARN_ON_ONCE(ci->ci_inode->i_ino == 0);
> + WARN_ON_ONCE(fscrypt_get_info_ino(ci) == 0);
> WARN_ON_ONCE(!mk->mk_ino_hash_key_initialized);
>
> - ci->ci_hashed_ino = (u32)siphash_1u64(ci->ci_inode->i_ino,
> + ci->ci_hashed_ino = (u32)siphash_1u64(fscrypt_get_info_ino(ci),
> &mk->mk_ino_hash_key);
> }
>
> @@ -705,7 +705,7 @@ fscrypt_setup_encryption_info(struct inode *inode,
> if (res)
> goto out;
>
> - if (inode->i_ino)
> + if (fscrypt_get_info_ino(crypt_info))
> fscrypt_hash_inode_number(crypt_info, mk);
> }
>
> diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
> index c895b12737a1..2a64e7a71a53 100644
> --- a/include/linux/fscrypt.h
> +++ b/include/linux/fscrypt.h
> @@ -160,6 +160,15 @@ struct fscrypt_operations {
> void (*get_ino_and_lblk_bits)(struct super_block *sb,
> int *ino_bits_ret, int *lblk_bits_ret);
>
> + /*
> + * Get the inode number equivalent for filesystems using per-extent
> + * encryption keys.
> + *
> + * This function only needs to be implemented if support for one of the
> + * FSCRYPT_POLICY_FLAG_IV_INO_* flags is needed.
> + */
> + u64 (*get_extent_ino_equivalent)(struct fscrypt_info **info_ptr);
> +
I went and looked at your tree and nobody actually uses this. I understand
wanting to add something for future expansion, but we're just sort of adding
things and hoping they'll be useful one day. I think it's best to leave this
off and if somebody needs it they can add it later. Thanks,
Josef
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