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-rw-r--r--fs/crypto/hooks.c30
-rw-r--r--include/linux/fscrypt.h33
-rw-r--r--include/linux/fscrypt_notsupp.h9
-rw-r--r--include/linux/fscrypt_supp.h5
4 files changed, 77 insertions, 0 deletions
diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c
index 8b90217320dd..822cb78f9b45 100644
--- a/fs/crypto/hooks.c
+++ b/fs/crypto/hooks.c
@@ -62,3 +62,33 @@ int __fscrypt_prepare_link(struct inode *inode, struct inode *dir)
return 0;
}
EXPORT_SYMBOL_GPL(__fscrypt_prepare_link);
+
+int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry,
+ unsigned int flags)
+{
+ int err;
+
+ err = fscrypt_require_key(old_dir);
+ if (err)
+ return err;
+
+ err = fscrypt_require_key(new_dir);
+ if (err)
+ return err;
+
+ if (old_dir != new_dir) {
+ if (IS_ENCRYPTED(new_dir) &&
+ !fscrypt_has_permitted_context(new_dir,
+ d_inode(old_dentry)))
+ return -EPERM;
+
+ if ((flags & RENAME_EXCHANGE) &&
+ IS_ENCRYPTED(old_dir) &&
+ !fscrypt_has_permitted_context(old_dir,
+ d_inode(new_dentry)))
+ return -EPERM;
+ }
+ return 0;
+}
+EXPORT_SYMBOL_GPL(__fscrypt_prepare_rename);
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 9c9a53f99327..c422367baed9 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -204,4 +204,37 @@ static inline int fscrypt_prepare_link(struct dentry *old_dentry,
return 0;
}
+/**
+ * fscrypt_prepare_rename - prepare for a rename between possibly-encrypted directories
+ * @old_dir: source directory
+ * @old_dentry: dentry for source file
+ * @new_dir: target directory
+ * @new_dentry: dentry for target location (may be negative unless exchanging)
+ * @flags: rename flags (we care at least about %RENAME_EXCHANGE)
+ *
+ * Prepare for ->rename() where the source and/or target directories may be
+ * encrypted. A new link can only be added to an encrypted directory if the
+ * directory's encryption key is available --- since otherwise we'd have no way
+ * to encrypt the filename. A rename to an existing name, on the other hand,
+ * *is* cryptographically possible without the key. However, we take the more
+ * conservative approach and just forbid all no-key renames.
+ *
+ * We also verify that the rename will not violate the constraint that all files
+ * in an encrypted directory tree use the same encryption policy.
+ *
+ * Return: 0 on success, -ENOKEY if an encryption key is missing, -EPERM if the
+ * rename would cause inconsistent encryption policies, or another -errno code.
+ */
+static inline int fscrypt_prepare_rename(struct inode *old_dir,
+ struct dentry *old_dentry,
+ struct inode *new_dir,
+ struct dentry *new_dentry,
+ unsigned int flags)
+{
+ if (IS_ENCRYPTED(old_dir) || IS_ENCRYPTED(new_dir))
+ return __fscrypt_prepare_rename(old_dir, old_dentry,
+ new_dir, new_dentry, flags);
+ return 0;
+}
+
#endif /* _LINUX_FSCRYPT_H */
diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
index d7d1039eb6b5..6af378d8126e 100644
--- a/include/linux/fscrypt_notsupp.h
+++ b/include/linux/fscrypt_notsupp.h
@@ -192,4 +192,13 @@ static inline int __fscrypt_prepare_link(struct inode *inode,
return -EOPNOTSUPP;
}
+static inline int __fscrypt_prepare_rename(struct inode *old_dir,
+ struct dentry *old_dentry,
+ struct inode *new_dir,
+ struct dentry *new_dentry,
+ unsigned int flags)
+{
+ return -EOPNOTSUPP;
+}
+
#endif /* _LINUX_FSCRYPT_NOTSUPP_H */
diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h
index 80706283da75..40f35073145f 100644
--- a/include/linux/fscrypt_supp.h
+++ b/include/linux/fscrypt_supp.h
@@ -146,5 +146,10 @@ extern int fscrypt_zeroout_range(const struct inode *, pgoff_t, sector_t,
/* hooks.c */
extern int fscrypt_file_open(struct inode *inode, struct file *filp);
extern int __fscrypt_prepare_link(struct inode *inode, struct inode *dir);
+extern int __fscrypt_prepare_rename(struct inode *old_dir,
+ struct dentry *old_dentry,
+ struct inode *new_dir,
+ struct dentry *new_dentry,
+ unsigned int flags);
#endif /* _LINUX_FSCRYPT_SUPP_H */