9c70776 added validation for the packet size in packet_snd. This change
enforced that every packet needs a long enough header and at least one
byte payload.
However, when trying to establish a PPPoE connection the following message
is printed every time a PPPoE discovery packet is sent:
pppd: packet size is too short (24 <= 24)
>From what I can see in the PPPoE code the "PADI" discovery packet can
consist of only a header with no payload (when there is neither a service
name nor a Host-Uniq configured).
Signed-off-by: Martin Blumenstingl <martin.blumensti...@googlemail.com>
---
net/packet/af_packet.c | 27 +++++++++++++--------------
1 file changed, 13 insertions(+), 14 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index c9e8741..d983f8f 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2199,18 +2199,6 @@ static void tpacket_destruct_skb(struct sk_buff *skb)
sock_wfree(skb);
}
-static bool ll_header_truncated(const struct net_device *dev, int len)
-{
- /* net device doesn't like empty head */
- if (unlikely(len <= dev->hard_header_len)) {
- net_warn_ratelimited("%s: packet size is too short (%d <=
%d)\n",
- current->comm, len, dev->hard_header_len);
- return true;
- }
-
- return false;
-}
-
static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
void *frame, struct net_device *dev, int size_max,
__be16 proto, unsigned char *addr, int hlen)
@@ -2286,8 +2274,14 @@ static int tpacket_fill_skb(struct packet_sock *po,
struct sk_buff *skb,
if (unlikely(err < 0))
return -EINVAL;
} else if (dev->hard_header_len) {
- if (ll_header_truncated(dev, tp_len))
+ /* net device doesn't like empty head */
+ if (unlikely(len <= dev->hard_header_len)) {
+ net_warn_ratelimited("%s: packet size is too short "
+ "(%d <= %d)\n",
+ current->comm, len,
+ dev->hard_header_len);
return -EINVAL;
+ }
skb_push(skb, dev->hard_header_len);
err = skb_store_bits(skb, 0, data,
@@ -2624,8 +2618,13 @@ static int packet_snd(struct socket *sock, struct msghdr
*msg, size_t len)
if (unlikely(offset < 0))
goto out_free;
} else {
- if (ll_header_truncated(dev, len))
+ if (unlikely(len < dev->hard_header_len)) {
+ net_warn_ratelimited("%s: packet size is shorter than "
+ "minimum header size (%d < %d)\n",
+ current->comm, len,
+ dev->hard_header_len);
goto out_free;
+ }
}
/* Returns -EFAULT on error */
--
2.4.6
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