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skbuff: introduce skb_gso_validate_mtu 

skb_gso_network_seglen is not enough for checking fragment sizes if
skb is using GSO_BY_FRAGS as we have to check frag per frag.

This patch introduces skb_gso_validate_mtu, based on the former, which
will wrap the use case inside it as all calls to skb_gso_network_seglen
were to validate if it fits on a given TMU, and improve the check.

Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Tested-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
hifive-unleashed-5.1
Marcelo Ricardo Leitner 2016-06-02 15:05:41 -03:00 committed by David S. Miller
parent 3953c46c3a
commit ae7ef81ef0
6 changed files with 36 additions and 4 deletions
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1
include/linux/skbuff.h
View File

@ -2992,6 +2992,7 @@ 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);
unsigned int skb_gso_transport_seglen(const struct sk_buff *skb);
bool skb_gso_validate_mtu(const struct sk_buff *skb, unsigned int mtu);
struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features);
struct sk_buff *skb_vlan_untag(struct sk_buff *skb);
int skb_ensure_writable(struct sk_buff *skb, int write_len);

31
net/core/skbuff.c
View File

@ -4392,6 +4392,37 @@ unsigned int skb_gso_transport_seglen(const struct sk_buff *skb)
}
EXPORT_SYMBOL_GPL(skb_gso_transport_seglen);
/**
* skb_gso_validate_mtu - Return in case such skb fits a given MTU
*
* @skb: GSO skb
*
* skb_gso_validate_mtu validates if a given skb will fit a wanted MTU
* once split.
*/
bool skb_gso_validate_mtu(const struct sk_buff *skb, unsigned int mtu)
{
const struct skb_shared_info *shinfo = skb_shinfo(skb);
const struct sk_buff *iter;
unsigned int hlen;
hlen = skb_gso_network_seglen(skb);
if (shinfo->gso_size != GSO_BY_FRAGS)
return hlen <= mtu;
/* Undo this so we can re-use header sizes */
hlen -= GSO_BY_FRAGS;
skb_walk_frags(skb, iter) {
if (hlen + skb_headlen(iter) > mtu)
return false;
}
return true;
}
EXPORT_SYMBOL_GPL(skb_gso_validate_mtu);
static struct sk_buff *skb_reorder_vlan_header(struct sk_buff *skb)
{
if (skb_cow(skb, skb_headroom(skb)) < 0) {

2
net/ipv4/ip_forward.c
View File

@ -54,7 +54,7 @@ static bool ip_exceeds_mtu(const struct sk_buff *skb, unsigned int mtu)
if (skb->ignore_df)
return false;
if (skb_is_gso(skb) && skb_gso_network_seglen(skb) <= mtu)
if (skb_is_gso(skb) && skb_gso_validate_mtu(skb, mtu))
return false;
return true;

2
net/ipv4/ip_output.c
View File

@ -225,7 +225,7 @@ static int ip_finish_output_gso(struct net *net, struct sock *sk,
/* common case: locally created skb or seglen is <= mtu */
if (((IPCB(skb)->flags & IPSKB_FORWARDED) == 0) ||
skb_gso_network_seglen(skb) <= mtu)
skb_gso_validate_mtu(skb, mtu))
return ip_finish_output2(net, sk, skb);
/* Slowpath - GSO segment length is exceeding the dst MTU.

2
net/ipv6/ip6_output.c
View File

@ -368,7 +368,7 @@ static bool ip6_pkt_too_big(const struct sk_buff *skb, unsigned int mtu)
if (skb->ignore_df)
return false;
if (skb_is_gso(skb) && skb_gso_network_seglen(skb) <= mtu)
if (skb_is_gso(skb) && skb_gso_validate_mtu(skb, mtu))
return false;
return true;

2
net/mpls/af_mpls.c
View File

@ -91,7 +91,7 @@ bool mpls_pkt_too_big(const struct sk_buff *skb, unsigned int mtu)
if (skb->len <= mtu)
return false;
if (skb_is_gso(skb) && skb_gso_network_seglen(skb) <= mtu)
if (skb_is_gso(skb) && skb_gso_validate_mtu(skb, mtu))
return false;
return true;