1 files changed, 53 insertions, 0 deletions
diff --git a/fs/ceph/crypto.c b/fs/ceph/crypto.c
index 0bb4d8e9f3b0..6dc723e8d395 100644
--- a/fs/ceph/crypto.c
+++ b/fs/ceph/crypto.c
@@ -191,3 +191,56 @@ void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req,
 {
 	swap(req->r_fscrypt_auth, as->fscrypt_auth);
 }
+
+int ceph_encode_encrypted_fname(const struct inode *parent,
+				struct dentry *dentry, char *buf)
+{
+	u32 len;
+	int elen;
+	int ret;
+	u8 *cryptbuf;
+
+	WARN_ON_ONCE(!fscrypt_has_encryption_key(parent));
+
+	/*
+	 * Convert cleartext d_name to ciphertext. If result is longer than
+	 * CEPH_NOHASH_NAME_MAX, sha256 the remaining bytes
+	 *
+	 * See: fscrypt_setup_filename
+	 */
+	if (!fscrypt_fname_encrypted_size(parent, dentry->d_name.len, NAME_MAX,
+					  &len))
+		return -ENAMETOOLONG;
+
+	/* Allocate a buffer appropriate to hold the result */
+	cryptbuf = kmalloc(len > CEPH_NOHASH_NAME_MAX ? NAME_MAX : len,
+			   GFP_KERNEL);
+	if (!cryptbuf)
+		return -ENOMEM;
+
+	ret = fscrypt_fname_encrypt(parent, &dentry->d_name, cryptbuf, len);
+	if (ret) {
+		kfree(cryptbuf);
+		return ret;
+	}
+
+	/* hash the end if the name is long enough */
+	if (len > CEPH_NOHASH_NAME_MAX) {
+		u8 hash[SHA256_DIGEST_SIZE];
+		u8 *extra = cryptbuf + CEPH_NOHASH_NAME_MAX;
+
+		/*
+		 * hash the extra bytes and overwrite crypttext beyond that
+		 * point with it
+		 */
+		sha256(extra, len - CEPH_NOHASH_NAME_MAX, hash);
+		memcpy(extra, hash, SHA256_DIGEST_SIZE);
+		len = CEPH_NOHASH_NAME_MAX + SHA256_DIGEST_SIZE;
+	}
+
+	/* base64 encode the encrypted name */
+	elen = ceph_base64_encode(cryptbuf, len, buf);
+	kfree(cryptbuf);
+	dout("base64-encoded ciphertext name = %.*s\n", elen, buf);
+	return elen;
+}