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: Dave Chinner <dchinner@redhat.com> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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@ -92,3 +92,21 @@ int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry,
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return 0;
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}
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EXPORT_SYMBOL_GPL(__fscrypt_prepare_rename);
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int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry)
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{
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int err = fscrypt_get_encryption_info(dir);
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if (err)
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return err;
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if (fscrypt_has_encryption_key(dir)) {
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spin_lock(&dentry->d_lock);
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dentry->d_flags |= DCACHE_ENCRYPTED_WITH_KEY;
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spin_unlock(&dentry->d_lock);
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}
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d_set_d_op(dentry, &fscrypt_d_ops);
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return 0;
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}
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EXPORT_SYMBOL_GPL(__fscrypt_prepare_lookup);
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@ -237,4 +237,32 @@ static inline int fscrypt_prepare_rename(struct inode *old_dir,
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return 0;
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}
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/**
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* fscrypt_prepare_lookup - prepare to lookup a name in a possibly-encrypted directory
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* @dir: directory being searched
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* @dentry: filename being looked up
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* @flags: lookup flags
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*
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* Prepare for ->lookup() in a directory which may be encrypted. Lookups can be
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* done with or without the directory's encryption key; without the key,
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* filenames are presented in encrypted form. Therefore, we'll try to set up
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* the directory's encryption key, but even without it the lookup can continue.
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*
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* To allow invalidating stale dentries if the directory's encryption key is
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* added later, we also install a custom ->d_revalidate() method and use the
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* DCACHE_ENCRYPTED_WITH_KEY flag to indicate whether a given dentry is a
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* plaintext name (flag set) or a ciphertext name (flag cleared).
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*
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* Return: 0 on success, -errno if a problem occurred while setting up the
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* encryption key
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*/
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static inline int fscrypt_prepare_lookup(struct inode *dir,
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struct dentry *dentry,
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unsigned int flags)
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{
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if (IS_ENCRYPTED(dir))
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return __fscrypt_prepare_lookup(dir, dentry);
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return 0;
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}
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#endif /* _LINUX_FSCRYPT_H */
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@ -201,4 +201,10 @@ static inline int __fscrypt_prepare_rename(struct inode *old_dir,
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return -EOPNOTSUPP;
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}
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static inline int __fscrypt_prepare_lookup(struct inode *dir,
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struct dentry *dentry)
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{
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return -EOPNOTSUPP;
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}
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#endif /* _LINUX_FSCRYPT_NOTSUPP_H */
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@ -151,5 +151,6 @@ extern int __fscrypt_prepare_rename(struct inode *old_dir,
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struct inode *new_dir,
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struct dentry *new_dentry,
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unsigned int flags);
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extern int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry);
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#endif /* _LINUX_FSCRYPT_SUPP_H */
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