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Commit 91d09c05 authored by Eric Biggers's avatar Eric Biggers Committed by Jaegeuk Kim
Browse files

fscrypt: new helper function - fscrypt_prepare_lookup() 



Introduce a helper function which prepares to look up the given dentry
in the given directory.  If the directory is encrypted, it handles
loading the directory's encryption key, setting the dentry's ->d_op to
fscrypt_d_ops, and setting DCACHE_ENCRYPTED_WITH_KEY if the directory's
encryption key is available.

Note: once all filesystems switch over to this, we'll be able to move
fscrypt_d_ops and fscrypt_set_encrypted_dentry() to fscrypt_private.h.

Acked-by: default avatarDave Chinner <dchinner@redhat.com>
Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 9a24d618

fs/crypto/hooks.c

+18 −0
Original line number Diff line number Diff line
@@ -92,3 +92,21 @@ int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry, 
	return 0;

}

EXPORT_SYMBOL_GPL(__fscrypt_prepare_rename);



int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry)

{

	int err = fscrypt_get_encryption_info(dir);



	if (err)

		return err;



	if (fscrypt_has_encryption_key(dir)) {

		spin_lock(&dentry->d_lock);

		dentry->d_flags |= DCACHE_ENCRYPTED_WITH_KEY;

		spin_unlock(&dentry->d_lock);

	}



	d_set_d_op(dentry, &fscrypt_d_ops);

	return 0;

}

EXPORT_SYMBOL_GPL(__fscrypt_prepare_lookup);

include/linux/fscrypt.h

+28 −0
Original line number Diff line number Diff line
@@ -238,4 +238,32 @@ static inline int fscrypt_prepare_rename(struct inode *old_dir, 
	return 0;

}



/**

 * fscrypt_prepare_lookup - prepare to lookup a name in a possibly-encrypted directory

 * @dir: directory being searched

 * @dentry: filename being looked up

 * @flags: lookup flags

 *

 * Prepare for ->lookup() in a directory which may be encrypted.  Lookups can be

 * done with or without the directory's encryption key; without the key,

 * filenames are presented in encrypted form.  Therefore, we'll try to set up

 * the directory's encryption key, but even without it the lookup can continue.

 *

 * To allow invalidating stale dentries if the directory's encryption key is

 * added later, we also install a custom ->d_revalidate() method and use the

 * DCACHE_ENCRYPTED_WITH_KEY flag to indicate whether a given dentry is a

 * plaintext name (flag set) or a ciphertext name (flag cleared).

 *

 * Return: 0 on success, -errno if a problem occurred while setting up the

 * encryption key

 */

static inline int fscrypt_prepare_lookup(struct inode *dir,

					 struct dentry *dentry,

					 unsigned int flags)

{

	if (IS_ENCRYPTED(dir))

		return __fscrypt_prepare_lookup(dir, dentry);

	return 0;

}



#endif	/* _LINUX_FSCRYPT_H */

include/linux/fscrypt_notsupp.h

+6 −0
Original line number Diff line number Diff line
@@ -202,4 +202,10 @@ static inline int __fscrypt_prepare_rename(struct inode *old_dir, 
	return -EOPNOTSUPP;

}



static inline int __fscrypt_prepare_lookup(struct inode *dir,

					   struct dentry *dentry)

{

	return -EOPNOTSUPP;

}



#endif	/* _LINUX_FSCRYPT_NOTSUPP_H */

include/linux/fscrypt_supp.h

+1 −0
Original line number Diff line number Diff line
@@ -152,5 +152,6 @@ extern int __fscrypt_prepare_rename(struct inode *old_dir, 
				    struct inode *new_dir,

				    struct dentry *new_dentry,

				    unsigned int flags);

extern int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry);



#endif	/* _LINUX_FSCRYPT_SUPP_H */