[Devel] Re: [PATCH 1/4] Record and restore skb header marks

[Serge E. Hallyn]

Quoting Dan Smith (danms at us.ibm.com):
> Save this information when we checkpoint an skb and provide a mechanism
> to restore that information on restart.  This will be used in the
> subsequent INET patch.
> 
> Signed-off-by: Dan Smith <danms at us.ibm.com>
> ---
>  include/linux/checkpoint.h     |    2 ++
>  include/linux/checkpoint_hdr.h |    7 +++++++
>  net/checkpoint.c               |   33 +++++++++++++++++++++++++++++++++
>  3 files changed, 42 insertions(+), 0 deletions(-)
> 
> diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
> index 4b61378..1da0b04 100644
> --- a/include/linux/checkpoint.h
> +++ b/include/linux/checkpoint.h
> @@ -100,6 +100,8 @@ extern int ckpt_sock_getnames(struct ckpt_ctx *ctx,
>  			      struct socket *socket,
>  			      struct sockaddr *loc, unsigned *loc_len,
>  			      struct sockaddr *rem, unsigned *rem_len);
> +void sock_restore_header_info(struct sk_buff *skb,
> +			      struct ckpt_hdr_socket_buffer *h);
> 
>  /* ckpt kflags */
>  #define ckpt_set_ctx_kflag(__ctx, __kflag)  \
> diff --git a/include/linux/checkpoint_hdr.h b/include/linux/checkpoint_hdr.h
> index ca2500d..3e6cab1 100644
> --- a/include/linux/checkpoint_hdr.h
> +++ b/include/linux/checkpoint_hdr.h
> @@ -542,8 +542,15 @@ struct ckpt_hdr_socket_queue {
> 
>  struct ckpt_hdr_socket_buffer {
>  	struct ckpt_hdr h;
> +	__u64 mac_len;
> +	__u64 hdr_len;
> +	__u64 transport_header;
> +	__u64 network_header;
> +	__u64 mac_header;
>  	__s32 sk_objref;
>  	__s32 pr_objref;
> +	__u16 protocol;
> +	__u8 cb[48];
>  };
> 
>  #define CKPT_UNIX_LINKED 1
> diff --git a/net/checkpoint.c b/net/checkpoint.c
> index dd23efd..5ed2724 100644
> --- a/net/checkpoint.c
> +++ b/net/checkpoint.c
> @@ -88,6 +88,38 @@ static int sock_copy_buffers(struct sk_buff_head *from,
>  	return -EAGAIN;
>  }
> 
> +static void sock_record_header_info(struct sk_buff *skb,
> +				    struct ckpt_hdr_socket_buffer *h)
> +{
> +
> +	h->mac_len = skb->mac_len;
> +	h->hdr_len = skb->hdr_len;
> +
> +#ifdef NET_SKBUFF_DATA_USES_OFFSET
> +	h->transport_header = skb->transport_hdr;
> +	h->network_header = skb->network_header;
> +	h->mac_header = skb->mac_header;
> +#else
> +	h->transport_header = skb->transport_header - skb->head;
> +	h->network_header = skb->network_header - skb->head;
> +	h->mac_header = skb->mac_header - skb->head;
> +#endif
> +
> +	memcpy(h->cb, skb->cb, sizeof(skb->cb));
> +}
> +
> +void sock_restore_header_info(struct sk_buff *skb,
> +			      struct ckpt_hdr_socket_buffer *h)
> +{
> +	skb->mac_len = h->mac_len;
> +	skb->hdr_len = h->hdr_len;
> +	skb_set_transport_header(skb, h->transport_header);
> +	skb_set_network_header(skb, h->network_header);
> +	skb_set_mac_header(skb, h->mac_header);

Should you verify that each of these new headers is located
inside the skb?

> +
> +	memcpy(skb->cb, h->cb, sizeof(skb->cb));

verify that (h->h.len - (h->cb - h->h)) > sizeof(skb->cb))  ?

> +}
> +
>  static int __sock_write_buffers(struct ckpt_ctx *ctx,
>  				struct sk_buff_head *queue,
>  				int dst_objref)
> @@ -123,6 +155,7 @@ static int __sock_write_buffers(struct ckpt_ctx *ctx,
>  			goto end;
>  		h->sk_objref = ret;
>  		h->pr_objref = dst_objref;
> +		sock_record_header_info(skb, h);
> 
>  		ret = ckpt_write_obj(ctx, (struct ckpt_hdr *) h);
>  		if (ret < 0)
> -- 
> 1.6.2.5
> 
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