virtio: Implement skb_partial_csum_set, for setting partial csums on untrusted packets. (f35d9d8a) · Commits · 戴 / test

drivers/net/virtio_net.c

+1 −10

Original line number	Diff line number	Diff line
		@@ -83,18 +83,9 @@ static void receive_skb(struct net_device dev, struct sk_buff skb,

		if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
		pr_debug("Needs csum!\n");
		skb->ip_summed = CHECKSUM_PARTIAL;
		skb->csum_start = hdr->csum_start;
		skb->csum_offset = hdr->csum_offset;
		if (skb->csum_start > skb->len - 2
		\|\| skb->csum_offset > skb->len - 2) {
		if (net_ratelimit())
		printk(KERN_WARNING "%s: csum=%u/%u len=%u\n",
		dev->name, skb->csum_start,
		skb->csum_offset, skb->len);
		if (!skb_partial_csum_set(skb,hdr->csum_start,hdr->csum_offset))
		goto frame_err;
		}
		}

		if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
		pr_debug("GSO!\n");

+1 −0

Original line number	Diff line number	Diff line
		@@ -1810,5 +1810,6 @@ static inline void skb_forward_csum(struct sk_buff *skb)
		skb->ip_summed = CHECKSUM_NONE;
		}

		bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
		#endif /* __KERNEL__ */
		#endif /* _LINUX_SKBUFF_H */

+29 −0

Original line number	Diff line number	Diff line
		@@ -2461,6 +2461,34 @@ int skb_cow_data(struct sk_buff skb, int tailbits, struct sk_buff *trailer)
		return elt;
		}

		/**
		* skb_partial_csum_set - set up and verify partial csum values for packet
		* @skb: the skb to set
		* @start: the number of bytes after skb->data to start checksumming.
		* @off: the offset from start to place the checksum.
		*
		* For untrusted partially-checksummed packets, we need to make sure the values
		* for skb->csum_start and skb->csum_offset are valid so we don't oops.
		*
		* This function checks and sets those values and skb->ip_summed: if this
		* returns false you should drop the packet.
		*/
		bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
		{
		if (unlikely(start > skb->len - 2) \|\|
		unlikely((int)start + off > skb->len - 2)) {
		if (net_ratelimit())
		printk(KERN_WARNING
		"bad partial csum: csum=%u/%u len=%u\n",
		start, off, skb->len);
		return false;
		}
		skb->ip_summed = CHECKSUM_PARTIAL;
		skb->csum_start = skb_headroom(skb) + start;
		skb->csum_offset = off;
		return true;
		}

		EXPORT_SYMBOL(___pskb_trim);
		EXPORT_SYMBOL(__kfree_skb);
		EXPORT_SYMBOL(kfree_skb);
		@@ -2497,3 +2525,4 @@ EXPORT_SYMBOL(skb_append_datato_frags);

		EXPORT_SYMBOL_GPL(skb_to_sgvec);
		EXPORT_SYMBOL_GPL(skb_cow_data);
		EXPORT_SYMBOL_GPL(skb_partial_csum_set);