From: Eric Biggers <ebiggers@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
fs/crypto/hooks.c | 18 ++++++++++++++++++
include/linux/fscrypt.h | 28 ++++++++++++++++++++++++++++
include/linux/fscrypt_notsupp.h | 6 ++++++
include/linux/fscrypt_supp.h | 1 +
4 files changed, 53 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.h b/include/linux/fscrypt.h
index c422367baed9..2327859c8cd2 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -237,4 +237,32 @@ 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 */
diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
index 6af378d8126e..c4c6bf2c390e 100644
--- a/include/linux/fscrypt_notsupp.h
+++ b/include/linux/fscrypt_notsupp.h
@@ -201,4 +201,10 @@ 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 */
diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h
index 40f35073145f..2db5e9706f60 100644
--- a/include/linux/fscrypt_supp.h
+++ b/include/linux/fscrypt_supp.h
@@ -151,5 +151,6 @@ 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 */
--
2.14.2.920.gcf0c67979c-goog
