[PATCH 09/25] fscrypt: new helper function - fscrypt_prepare_lookup()
From: Eric Biggers <hidden>
Date: 2017-09-20 22:47:02
Also in:
linux-f2fs-devel, linux-fscrypt, linux-fsdevel
Subsystem:
filesystems (vfs and infrastructure), fscrypt: file system level encryption support, the rest · Maintainers:
Alexander Viro, Christian Brauner, Eric Biggers, Theodore Y. Ts'o, Jaegeuk Kim, Linus Torvalds
From: Eric Biggers <redacted> 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. Signed-off-by: Eric Biggers <redacted> --- fs/crypto/hooks.c | 18 ++++++++++++++++++ include/linux/fscrypt_notsupp.h | 9 +++++++++ include/linux/fscrypt_supp.h | 30 ++++++++++++++++++++++++++++++ 3 files changed, 57 insertions(+)
diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c
index 822cb78f9b45..9f5fb2eb9cf7 100644
--- a/fs/crypto/hooks.c
+++ b/fs/crypto/hooks.c@@ -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);
diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
index a88a2959cd8c..e9b437605f9c 100644
--- a/include/linux/fscrypt_notsupp.h
+++ b/include/linux/fscrypt_notsupp.h@@ -209,4 +209,13 @@ static inline int fscrypt_prepare_rename(struct inode *old_dir, return 0; } +static inline int fscrypt_prepare_lookup(struct inode *dir, + struct dentry *dentry, + unsigned int flags) +{ + if (IS_ENCRYPTED(dir)) + return -EOPNOTSUPP; + return 0; +} + #endif /* _LINUX_FSCRYPT_NOTSUPP_H */
diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h
index fa062d41b39a..2b99bc01c59b 100644
--- a/include/linux/fscrypt_supp.h
+++ b/include/linux/fscrypt_supp.h@@ -240,4 +240,34 @@ static inline int fscrypt_prepare_rename(struct inode *old_dir, return 0; } +extern int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry); + +/** + * 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_SUPP_H */
--
2.14.1.821.g8fa685d3b7-goog
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