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Subject[PATCH] core, nfqueue, openvswitch: Orphan frags in skb_zerocopy and handle errors
Date
skb_zerocopy can copy elements of the frags array between skbs, but it doesn't
orphan them. Also, it doesn't handle errors, so this patch takes care of that
as well.

Signed-off-by: Zoltan Kiss <zoltan.kiss@citrix.com>
---
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 03db95a..35c4e85 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2508,8 +2508,8 @@ int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
unsigned int flags);
void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
unsigned int skb_zerocopy_headlen(const struct sk_buff *from);
-void skb_zerocopy(struct sk_buff *to, const struct sk_buff *from,
- int len, int hlen);
+int skb_zerocopy(struct sk_buff *to, const struct sk_buff *from,
+ int len, int hlen);
void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len);
int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen);
void skb_scrub_packet(struct sk_buff *skb, bool xnet);
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 3f14c63..60f623c 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2127,25 +2127,36 @@ EXPORT_SYMBOL_GPL(skb_zerocopy_headlen);
*
* The `hlen` as calculated by skb_zerocopy_headlen() specifies the
* headroom in the `to` buffer.
+ *
+ * Return value:
+ * 0: everything is OK
+ * -ENOMEM: couldn't orphan frags of from due to lack of memory
+ * -EFAULT: skb_copy_bits() found some problem with geometry
*/
-void
+int
skb_zerocopy(struct sk_buff *to, const struct sk_buff *from, int len, int hlen)
{
int i, j = 0;
int plen = 0; /* length of skb->head fragment */
+ int ret;
struct page *page;
unsigned int offset;

BUG_ON(!from->head_frag && !hlen);

/* dont bother with small payloads */
- if (len <= skb_tailroom(to)) {
- skb_copy_bits(from, 0, skb_put(to, len), len);
- return;
+ if (len <= skb_tailroom(to))
+ return skb_copy_bits(from, 0, skb_put(to, len), len);
+
+ if (unlikely(skb_orphan_frags(to, GFP_ATOMIC))) {
+ skb_tx_error(to);
+ return -ENOMEM;
}

if (hlen) {
- skb_copy_bits(from, 0, skb_put(to, hlen), hlen);
+ ret = skb_copy_bits(from, 0, skb_put(to, hlen), hlen);
+ if (unlikely(ret))
+ return ret;
len -= hlen;
} else {
plen = min_t(int, skb_headlen(from), len);
@@ -2173,6 +2184,8 @@ skb_zerocopy(struct sk_buff *to, const struct sk_buff *from, int len, int hlen)
j++;
}
skb_shinfo(to)->nr_frags = j;
+
+ return 0;
}
EXPORT_SYMBOL_GPL(skb_zerocopy);

diff --git a/net/netfilter/nfnetlink_queue_core.c b/net/netfilter/nfnetlink_queue_core.c
index f072fe8..ea02d16 100644
--- a/net/netfilter/nfnetlink_queue_core.c
+++ b/net/netfilter/nfnetlink_queue_core.c
@@ -488,7 +488,8 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
nla->nla_type = NFQA_PAYLOAD;
nla->nla_len = nla_attr_size(data_len);

- skb_zerocopy(skb, entskb, data_len, hlen);
+ if (skb_zerocopy(skb, entskb, data_len, hlen))
+ goto nla_put_failure;
}

nlh->nlmsg_len = skb->len;
diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index c53fe0c..9a9f668 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -464,7 +464,9 @@ static int queue_userspace_packet(struct datapath *dp, struct sk_buff *skb,
}
nla->nla_len = nla_attr_size(skb->len);

- skb_zerocopy(user_skb, skb, skb->len, hlen);
+ err = skb_zerocopy(user_skb, skb, skb->len, hlen);
+ if (err)
+ goto out;

/* Pad OVS_PACKET_ATTR_PACKET if linear copy was performed */
if (!(dp->user_features & OVS_DP_F_UNALIGNED)) {

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