Dan Smith wrote:
> This is an incremental step towards supporting checkpoint/restart on
> AF_INET sockets. In this scenario, any sockets that were in TCP_LISTEN
> state are restored as they were. Any that were connected are forced to
> TCP_CLOSE. This should cover a range of use cases that involve
> applications that are tolerant of such an interruption.
>
> Cc: Oren Laadan <[email protected]>
> Cc: Andrew Morton <[email protected]>
> Signed-off-by: Dan Smith <[email protected]>
> ---
Good stuff... a few comments below.
[...]
> +
> +static int inet_read_buffer(struct ckpt_ctx *ctx, struct sk_buff_head *queue)
> +{
> + struct ckpt_hdr_socket_buffer *h;
> + int len;
> + int ret;
> + struct sk_buff *skb;
> +
> + h = ckpt_read_obj_type(ctx, sizeof(*h), CKPT_HDR_SOCKET_BUFFER);
> + if (IS_ERR(h))
> + return PTR_ERR(h);
> +
> + len = _ckpt_read_obj_type(ctx, NULL, 0, CKPT_HDR_BUFFER);
> + if (len < 0) {
> + ret = len;
Note: skb wasn't initialized yet, ret will be negative (more below)...
> + goto out;
> + } else if (len > SKB_MAX_ALLOC) {
> + ckpt_debug("Socket buffer too big (%i > %lu)",
> + len, SKB_MAX_ALLOC);
> + ret = -ENOSPC;
> + goto out;
> + }
> +
> + skb = alloc_skb(len, GFP_KERNEL);
> + if (!skb) {
> + ret = -ENOMEM;
> + goto out;
> + }
> +
> + ret = ckpt_kread(ctx, skb_put(skb, len), len);
> + if (ret < 0)
> + goto out;
> +
> + spin_lock(&queue->lock);
> + skb_queue_tail(queue, skb);
> + spin_unlock(&queue->lock);
> + out:
> + ckpt_hdr_put(ctx, h);
> +
> + if (ret < 0)
> + kfree_skb(skb);
skb may be uninitialized at this point (do I sound like gcc ?)
> +
> + return ret;
> +}
> +
> +static int inet_read_buffers(struct ckpt_ctx *ctx, struct sk_buff_head
> *queue)
> +{
> + struct ckpt_hdr_socket_queue *h;
> + int ret = 0;
> + int i;
> +
> + h = ckpt_read_obj_type(ctx, sizeof(*h), CKPT_HDR_SOCKET_QUEUE);
> + if (IS_ERR(h))
> + return PTR_ERR(h);
> +
> + for (i = 0; i < h->skb_count; i++) {
> + ret = inet_read_buffer(ctx, queue);
> + ckpt_debug("read inet buffer %i: %i", i, ret);
> + if (ret < 0)
> + goto out;
> +
> + if (ret > h->total_bytes) {
> + ckpt_debug("Buffers exceeded claim");
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + h->total_bytes -= ret;
> + ret = 0;
^^^^^^^^
Unnecessary ?
> + }
> +
> + ret = h->skb_count;
> + out:
> + ckpt_hdr_put(ctx, h);
> +
> + return ret;
> +}
> +
> +static int inet_deferred_restore_buffers(void *data)
> +{
> + struct dq_buffers *dq = (struct dq_buffers *)data;
> + struct ckpt_ctx *ctx = dq->ctx;
> + struct sock *sk = dq->sk;
> + int ret;
> +
> + ret = inet_read_buffers(ctx, &sk->sk_receive_queue);
> + ckpt_debug("(R) inet_read_buffers: %i\n", ret);
> + if (ret < 0)
> + return ret;
> +
> + ret = inet_read_buffers(ctx, &sk->sk_write_queue);
> + ckpt_debug("(W) inet_read_buffers: %i\n", ret);
> +
> + return ret;
> +}
> +
> +static int inet_defer_restore_buffers(struct ckpt_ctx *ctx, struct sock *sk)
> +{
> + struct dq_buffers dq;
> +
> + dq.ctx = ctx;
> + dq.sk = sk;
> +
> + return deferqueue_add(ctx->files_deferq, &dq, sizeof(dq),
> + inet_deferred_restore_buffers, NULL);
> +}
> +
> +int inet_restore(struct ckpt_ctx *ctx,
> + struct socket *sock,
> + struct ckpt_hdr_socket *h)
> +{
> + struct ckpt_hdr_socket_inet *in;
> + int ret = 0;
> +
> + in = ckpt_read_obj_type(ctx, sizeof(*in), CKPT_HDR_SOCKET_INET);
> + if (IS_ERR(in))
> + return PTR_ERR(in);
I think you need to at least sanitize the in->laddr_len field - the
ops->bind() below assumes its valid.
> +
> + /* Listening sockets and those that are closed but have a local
> + * address need to call bind()
> + */
> + if ((h->sock.state == TCP_LISTEN) ||
> + ((h->sock.state == TCP_CLOSE) && (in->laddr_len > 0))) {
> + sock->sk->sk_reuse = 2;
> + inet_sk(sock->sk)->freebind = 1;
> + ret = sock->ops->bind(sock,
> + (struct sockaddr *)&in->laddr,
> + in->laddr_len);
> + ckpt_debug("inet bind: %i\n", ret);
> + if (ret < 0)
> + goto out;
> +
> + if (h->sock.state == TCP_LISTEN) {
> + ret = sock->ops->listen(sock, h->sock.backlog);
> + ckpt_debug("inet listen: %i\n", ret);
> + if (ret < 0)
> + goto out;
> + }
> + } else {
> + if (!sock_flag(sock->sk, SOCK_DEAD))
> + ret = inet_defer_restore_buffers(ctx, sock->sk);
> + }
> + out:
> + ckpt_hdr_put(ctx, in);
> +
> + return ret;
> + }
> +
Oren.
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