From: Luís Henriques <lhenriques@xxxxxxx> This patch introduces a new helper function which can be used both in lookups and in atomic_open operations by filesystems that want to handle filename encryption and no-key dentries themselves. The reason for this function to be used in atomic open is that this operation can act as a lookup if handed a dentry that is negative. And in this case we may need to set DCACHE_NOKEY_NAME. Signed-off-by: Luís Henriques <lhenriques@xxxxxxx> Tested-by: Xiubo Li <xiubli@xxxxxxxxxx> Reviewed-by: Xiubo Li <xiubli@xxxxxxxxxx> [ebiggers: improved the function comment, and moved the function to just below __fscrypt_prepare_lookup()] Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> --- fs/crypto/hooks.c | 30 ++++++++++++++++++++++++++++++ include/linux/fscrypt.h | 7 +++++++ 2 files changed, 37 insertions(+) diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c index 7b8c5a1104b58..9151934c50866 100644 --- a/fs/crypto/hooks.c +++ b/fs/crypto/hooks.c @@ -111,6 +111,36 @@ int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry, } EXPORT_SYMBOL_GPL(__fscrypt_prepare_lookup); +/** + * fscrypt_prepare_lookup_partial() - prepare lookup without filename setup + * @dir: the encrypted directory being searched + * @dentry: the dentry being looked up in @dir + * + * This function should be used by the ->lookup and ->atomic_open methods of + * filesystems that handle filename encryption and no-key name encoding + * themselves and thus can't use fscrypt_prepare_lookup(). Like + * fscrypt_prepare_lookup(), this will try to set up the directory's encryption + * key and will set DCACHE_NOKEY_NAME on the dentry if the key is unavailable. + * However, this function doesn't set up a struct fscrypt_name for the filename. + * + * Return: 0 on success; -errno on error. Note that the encryption key being + * unavailable is not considered an error. It is also not an error if + * the encryption policy is unsupported by this kernel; that is treated + * like the key being unavailable, so that files can still be deleted. + */ +int fscrypt_prepare_lookup_partial(struct inode *dir, struct dentry *dentry) +{ + int err = fscrypt_get_encryption_info(dir, true); + + if (!err && !fscrypt_has_encryption_key(dir)) { + spin_lock(&dentry->d_lock); + dentry->d_flags |= DCACHE_NOKEY_NAME; + spin_unlock(&dentry->d_lock); + } + return err; +} +EXPORT_SYMBOL_GPL(fscrypt_prepare_lookup_partial); + int __fscrypt_prepare_readdir(struct inode *dir) { return fscrypt_get_encryption_info(dir, true); diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index e0a49c3125ebc..a69f1302051d3 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -359,6 +359,7 @@ int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry, unsigned int flags); int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry, struct fscrypt_name *fname); +int fscrypt_prepare_lookup_partial(struct inode *dir, struct dentry *dentry); int __fscrypt_prepare_readdir(struct inode *dir); int __fscrypt_prepare_setattr(struct dentry *dentry, struct iattr *attr); int fscrypt_prepare_setflags(struct inode *inode, @@ -673,6 +674,12 @@ static inline int __fscrypt_prepare_lookup(struct inode *dir, return -EOPNOTSUPP; } +static inline int fscrypt_prepare_lookup_partial(struct inode *dir, + struct dentry *dentry) +{ + return -EOPNOTSUPP; +} + static inline int __fscrypt_prepare_readdir(struct inode *dir) { return -EOPNOTSUPP; -- 2.40.0
![]() |