libceph: make recv path in secure mode work the same as send path

The recv path of secure mode is intertwined with that of crc mode.
While it's slightly more efficient that way (the ciphertext is read
into the destination buffer and decrypted in place, thus avoiding
two potentially heavy memory allocations for the bounce buffer and
the corresponding sg array), it isn't really amenable to changes.
Sacrifice that edge and align with the send path which always uses
a full-sized bounce buffer (currently there is no other way -- if
the kernel crypto API ever grows support for streaming (piecewise)
en/decryption for GCM [1], we would be able to easily take advantage
of that on both sides).

[1] https://lore.kernel.org/all/20141225202830.GA18794@gondor.apana.org.au/

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>

Author: idryomov

include/linux/ceph/messenger.h

@@ -383,6 +383,10 @@ struct ceph_connection_v2_info {
 	struct ceph_gcm_nonce in_gcm_nonce;
 	struct ceph_gcm_nonce out_gcm_nonce;
 
+	struct page **in_enc_pages;
+	int in_enc_page_cnt;
+	int in_enc_resid;
+	int in_enc_i;
 	struct page **out_enc_pages;
 	int out_enc_page_cnt;
 	int out_enc_resid;

net/ceph/messenger_v2.c

@@ -57,8 +57,9 @@
 #define IN_S_HANDLE_CONTROL_REMAINDER	3
 #define IN_S_PREPARE_READ_DATA		4
 #define IN_S_PREPARE_READ_DATA_CONT	5
-#define IN_S_HANDLE_EPILOGUE		6
-#define IN_S_FINISH_SKIP		7
+#define IN_S_PREPARE_READ_ENC_PAGE	6
+#define IN_S_HANDLE_EPILOGUE		7
+#define IN_S_FINISH_SKIP		8
 
 #define OUT_S_QUEUE_DATA		1
 #define OUT_S_QUEUE_DATA_CONT		2
@@ -1032,22 +1033,41 @@ static int decrypt_control_remainder(struct ceph_connection *con)
 			 padded_len(rem_len) + CEPH_GCM_TAG_LEN);
 }
 
-static int decrypt_message(struct ceph_connection *con)
+static int decrypt_tail(struct ceph_connection *con)
 {
+	struct sg_table enc_sgt = {};
 	struct sg_table sgt = {};
+	int tail_len;
 	int ret;
 
+	tail_len = tail_onwire_len(con->in_msg, true);
+	ret = sg_alloc_table_from_pages(&enc_sgt, con->v2.in_enc_pages,
+					con->v2.in_enc_page_cnt, 0, tail_len,
+					GFP_NOIO);
+	if (ret)
+		goto out;
+
 	ret = setup_message_sgs(&sgt, con->in_msg, FRONT_PAD(con->v2.in_buf),
 			MIDDLE_PAD(con->v2.in_buf), DATA_PAD(con->v2.in_buf),
 			con->v2.in_buf, true);
 	if (ret)
 		goto out;
 
-	ret = gcm_crypt(con, false, sgt.sgl, sgt.sgl,
-			tail_onwire_len(con->in_msg, true));
+	dout("%s con %p msg %p enc_page_cnt %d sg_cnt %d\n", __func__, con,
+	     con->in_msg, con->v2.in_enc_page_cnt, sgt.orig_nents);
+	ret = gcm_crypt(con, false, enc_sgt.sgl, sgt.sgl, tail_len);
+	if (ret)
+		goto out;
+
+	WARN_ON(!con->v2.in_enc_page_cnt);
+	ceph_release_page_vector(con->v2.in_enc_pages,
+				 con->v2.in_enc_page_cnt);
+	con->v2.in_enc_pages = NULL;
+	con->v2.in_enc_page_cnt = 0;
 
 out:
 	sg_free_table(&sgt);
+	sg_free_table(&enc_sgt);
 	return ret;
 }
 
@@ -1737,8 +1757,7 @@ static void prepare_read_data(struct ceph_connection *con)
 {
 	struct bio_vec bv;
 
-	if (!con_secure(con))
-		con->in_data_crc = -1;
+	con->in_data_crc = -1;
 	ceph_msg_data_cursor_init(&con->v2.in_cursor, con->in_msg,
 				  data_len(con->in_msg));
 
@@ -1751,11 +1770,10 @@ static void prepare_read_data_cont(struct ceph_connection *con)
 {
 	struct bio_vec bv;
 
-	if (!con_secure(con))
-		con->in_data_crc = ceph_crc32c_page(con->in_data_crc,
-						    con->v2.in_bvec.bv_page,
-						    con->v2.in_bvec.bv_offset,
-						    con->v2.in_bvec.bv_len);
+	con->in_data_crc = ceph_crc32c_page(con->in_data_crc,
+					    con->v2.in_bvec.bv_page,
+					    con->v2.in_bvec.bv_offset,
+					    con->v2.in_bvec.bv_len);
 
 	ceph_msg_data_advance(&con->v2.in_cursor, con->v2.in_bvec.bv_len);
 	if (con->v2.in_cursor.total_resid) {
@@ -1766,21 +1784,94 @@ static void prepare_read_data_cont(struct ceph_connection *con)
 	}
 
 	/*
-	 * We've read all data.  Prepare to read data padding (if any)
-	 * and epilogue.
+	 * We've read all data.  Prepare to read epilogue.
 	 */
 	reset_in_kvecs(con);
-	if (con_secure(con)) {
-		if (need_padding(data_len(con->in_msg)))
-			add_in_kvec(con, DATA_PAD(con->v2.in_buf),
-				    padding_len(data_len(con->in_msg)));
-		add_in_kvec(con, con->v2.in_buf, CEPH_EPILOGUE_SECURE_LEN);
+	add_in_kvec(con, con->v2.in_buf, CEPH_EPILOGUE_PLAIN_LEN);
+	con->v2.in_state = IN_S_HANDLE_EPILOGUE;
+}
+
+static void prepare_read_tail_plain(struct ceph_connection *con)
+{
+	struct ceph_msg *msg = con->in_msg;
+
+	if (!front_len(msg) && !middle_len(msg)) {
+		WARN_ON(!data_len(msg));
+		prepare_read_data(con);
+		return;
+	}
+
+	reset_in_kvecs(con);
+	if (front_len(msg)) {
+		add_in_kvec(con, msg->front.iov_base, front_len(msg));
+		WARN_ON(msg->front.iov_len != front_len(msg));
+	}
+	if (middle_len(msg)) {
+		add_in_kvec(con, msg->middle->vec.iov_base, middle_len(msg));
+		WARN_ON(msg->middle->vec.iov_len != middle_len(msg));
+	}
+
+	if (data_len(msg)) {
+		con->v2.in_state = IN_S_PREPARE_READ_DATA;
 	} else {
 		add_in_kvec(con, con->v2.in_buf, CEPH_EPILOGUE_PLAIN_LEN);
+		con->v2.in_state = IN_S_HANDLE_EPILOGUE;
+	}
+}
+
+static void prepare_read_enc_page(struct ceph_connection *con)
+{
+	struct bio_vec bv;
+
+	dout("%s con %p i %d resid %d\n", __func__, con, con->v2.in_enc_i,
+	     con->v2.in_enc_resid);
+	WARN_ON(!con->v2.in_enc_resid);
+
+	bv.bv_page = con->v2.in_enc_pages[con->v2.in_enc_i];
+	bv.bv_offset = 0;
+	bv.bv_len = min(con->v2.in_enc_resid, (int)PAGE_SIZE);
+
+	set_in_bvec(con, &bv);
+	con->v2.in_enc_i++;
+	con->v2.in_enc_resid -= bv.bv_len;
+
+	if (con->v2.in_enc_resid) {
+		con->v2.in_state = IN_S_PREPARE_READ_ENC_PAGE;
+		return;
 	}
+
+	/*
+	 * We are set to read the last piece of ciphertext (ending
+	 * with epilogue) + auth tag.
+	 */
+	WARN_ON(con->v2.in_enc_i != con->v2.in_enc_page_cnt);
 	con->v2.in_state = IN_S_HANDLE_EPILOGUE;
 }
 
+static int prepare_read_tail_secure(struct ceph_connection *con)
+{
+	struct page **enc_pages;
+	int enc_page_cnt;
+	int tail_len;
+
+	tail_len = tail_onwire_len(con->in_msg, true);
+	WARN_ON(!tail_len);
+
+	enc_page_cnt = calc_pages_for(0, tail_len);
+	enc_pages = ceph_alloc_page_vector(enc_page_cnt, GFP_NOIO);
+	if (IS_ERR(enc_pages))
+		return PTR_ERR(enc_pages);
+
+	WARN_ON(con->v2.in_enc_pages || con->v2.in_enc_page_cnt);
+	con->v2.in_enc_pages = enc_pages;
+	con->v2.in_enc_page_cnt = enc_page_cnt;
+	con->v2.in_enc_resid = tail_len;
+	con->v2.in_enc_i = 0;
+
+	prepare_read_enc_page(con);
+	return 0;
+}
+
 static void __finish_skip(struct ceph_connection *con)
 {
 	con->in_seq++;
@@ -2589,46 +2680,26 @@ static int __handle_control(struct ceph_connection *con, void *p)
 	}
 
 	msg = con->in_msg;  /* set in process_message_header() */
-	if (!front_len(msg) && !middle_len(msg)) {
-		if (!data_len(msg))
-			return process_message(con);
-
-		prepare_read_data(con);
-		return 0;
-	}
-
-	reset_in_kvecs(con);
 	if (front_len(msg)) {
 		WARN_ON(front_len(msg) > msg->front_alloc_len);
-		add_in_kvec(con, msg->front.iov_base, front_len(msg));
 		msg->front.iov_len = front_len(msg);
-
-		if (con_secure(con) && need_padding(front_len(msg)))
-			add_in_kvec(con, FRONT_PAD(con->v2.in_buf),
-				    padding_len(front_len(msg)));
 	} else {
 		msg->front.iov_len = 0;
 	}
 	if (middle_len(msg)) {
 		WARN_ON(middle_len(msg) > msg->middle->alloc_len);
-		add_in_kvec(con, msg->middle->vec.iov_base, middle_len(msg));
 		msg->middle->vec.iov_len = middle_len(msg);
-
-		if (con_secure(con) && need_padding(middle_len(msg)))
-			add_in_kvec(con, MIDDLE_PAD(con->v2.in_buf),
-				    padding_len(middle_len(msg)));
 	} else if (msg->middle) {
 		msg->middle->vec.iov_len = 0;
 	}
 
-	if (data_len(msg)) {
-		con->v2.in_state = IN_S_PREPARE_READ_DATA;
-	} else {
-		add_in_kvec(con, con->v2.in_buf,
-			    con_secure(con) ? CEPH_EPILOGUE_SECURE_LEN :
-					      CEPH_EPILOGUE_PLAIN_LEN);
-		con->v2.in_state = IN_S_HANDLE_EPILOGUE;
-	}
+	if (!front_len(msg) && !middle_len(msg) && !data_len(msg))
+		return process_message(con);
+
+	if (con_secure(con))
+		return prepare_read_tail_secure(con);
+
+	prepare_read_tail_plain(con);
 	return 0;
 }
 
@@ -2717,7 +2788,7 @@ static int handle_epilogue(struct ceph_connection *con)
 	int ret;
 
 	if (con_secure(con)) {
-		ret = decrypt_message(con);
+		ret = decrypt_tail(con);
 		if (ret) {
 			if (ret == -EBADMSG)
 				con->error_msg = "integrity error, bad epilogue auth tag";
@@ -2792,6 +2863,10 @@ static int populate_in_iter(struct ceph_connection *con)
 			prepare_read_data_cont(con);
 			ret = 0;
 			break;
+		case IN_S_PREPARE_READ_ENC_PAGE:
+			prepare_read_enc_page(con);
+			ret = 0;
+			break;
 		case IN_S_HANDLE_EPILOGUE:
 			ret = handle_epilogue(con);
 			break;
@@ -3326,20 +3401,16 @@ void ceph_con_v2_revoke(struct ceph_connection *con)
 
 static void revoke_at_prepare_read_data(struct ceph_connection *con)
 {
-	int remaining;  /* data + [data padding] + epilogue */
+	int remaining;
 	int resid;
 
+	WARN_ON(con_secure(con));
 	WARN_ON(!data_len(con->in_msg));
 	WARN_ON(!iov_iter_is_kvec(&con->v2.in_iter));
 	resid = iov_iter_count(&con->v2.in_iter);
 	WARN_ON(!resid);
 
-	if (con_secure(con))
-		remaining = padded_len(data_len(con->in_msg)) +
-			    CEPH_EPILOGUE_SECURE_LEN;
-	else
-		remaining = data_len(con->in_msg) + CEPH_EPILOGUE_PLAIN_LEN;
-
+	remaining = data_len(con->in_msg) + CEPH_EPILOGUE_PLAIN_LEN;
 	dout("%s con %p resid %d remaining %d\n", __func__, con, resid,
 	     remaining);
 	con->v2.in_iter.count -= resid;
@@ -3350,8 +3421,9 @@ static void revoke_at_prepare_read_data(struct ceph_connection *con)
 static void revoke_at_prepare_read_data_cont(struct ceph_connection *con)
 {
 	int recved, resid;  /* current piece of data */
-	int remaining;  /* [data padding] + epilogue */
+	int remaining;
 
+	WARN_ON(con_secure(con));
 	WARN_ON(!data_len(con->in_msg));
 	WARN_ON(!iov_iter_is_bvec(&con->v2.in_iter));
 	resid = iov_iter_count(&con->v2.in_iter);
@@ -3363,24 +3435,34 @@ static void revoke_at_prepare_read_data_cont(struct ceph_connection *con)
 		ceph_msg_data_advance(&con->v2.in_cursor, recved);
 	WARN_ON(resid > con->v2.in_cursor.total_resid);
 
-	if (con_secure(con))
-		remaining = padding_len(data_len(con->in_msg)) +
-			    CEPH_EPILOGUE_SECURE_LEN;
-	else
-		remaining = CEPH_EPILOGUE_PLAIN_LEN;
-
+	remaining = CEPH_EPILOGUE_PLAIN_LEN;
 	dout("%s con %p total_resid %zu remaining %d\n", __func__, con,
 	     con->v2.in_cursor.total_resid, remaining);
 	con->v2.in_iter.count -= resid;
 	set_in_skip(con, con->v2.in_cursor.total_resid + remaining);
 	con->v2.in_state = IN_S_FINISH_SKIP;
 }
 
+static void revoke_at_prepare_read_enc_page(struct ceph_connection *con)
+{
+	int resid;  /* current enc page (not necessarily data) */
+
+	WARN_ON(!con_secure(con));
+	WARN_ON(!iov_iter_is_bvec(&con->v2.in_iter));
+	resid = iov_iter_count(&con->v2.in_iter);
+	WARN_ON(!resid || resid > con->v2.in_bvec.bv_len);
+
+	dout("%s con %p resid %d enc_resid %d\n", __func__, con, resid,
+	     con->v2.in_enc_resid);
+	con->v2.in_iter.count -= resid;
+	set_in_skip(con, resid + con->v2.in_enc_resid);
+	con->v2.in_state = IN_S_FINISH_SKIP;
+}
+
 static void revoke_at_handle_epilogue(struct ceph_connection *con)
 {
 	int resid;
 
-	WARN_ON(!iov_iter_is_kvec(&con->v2.in_iter));
 	resid = iov_iter_count(&con->v2.in_iter);
 	WARN_ON(!resid);
 
@@ -3399,6 +3481,9 @@ void ceph_con_v2_revoke_incoming(struct ceph_connection *con)
 	case IN_S_PREPARE_READ_DATA_CONT:
 		revoke_at_prepare_read_data_cont(con);
 		break;
+	case IN_S_PREPARE_READ_ENC_PAGE:
+		revoke_at_prepare_read_enc_page(con);
+		break;
 	case IN_S_HANDLE_EPILOGUE:
 		revoke_at_handle_epilogue(con);
 		break;
@@ -3432,6 +3517,13 @@ void ceph_con_v2_reset_protocol(struct ceph_connection *con)
 	clear_out_sign_kvecs(con);
 	free_conn_bufs(con);
 
+	if (con->v2.in_enc_pages) {
+		WARN_ON(!con->v2.in_enc_page_cnt);
+		ceph_release_page_vector(con->v2.in_enc_pages,
+					 con->v2.in_enc_page_cnt);
+		con->v2.in_enc_pages = NULL;
+		con->v2.in_enc_page_cnt = 0;
+	}
 	if (con->v2.out_enc_pages) {
 		WARN_ON(!con->v2.out_enc_page_cnt);
 		ceph_release_page_vector(con->v2.out_enc_pages,