[PATCH 0/2] pull request for net: batman-adv 2018-11-14

[PATCH 0/2] pull request for net: batman-adv 2018-11-14

[Simon Wunderlich]

Hi David,

here are some bugfixes which we would like to see integrated into net.

Please pull or let me know of any problem!

Thank you,
      Simon

The following changes since commit 651022382c7f8da46cb4872a545ee1da6d097d2a:

  Linux 4.20-rc1 (2018-11-04 15:37:52 -0800)

are available in the git repository at:

  git://git.open-mesh.org/linux-merge.git tags/batadv-net-for-davem-20181114

for you to fetch changes up to d7d8bbb40a5b1f682ee6589e212934f4c6b8ad60:

  batman-adv: Expand merged fragment buffer for full packet (2018-11-12 10:41:29 +0100)

----------------------------------------------------------------
Here are two batman-adv bugfixes:

 - Explicitly pad short ELP packets with zeros, by Sven Eckelmann

 - Fix packet size calculation when merging fragments,
   by Sven Eckelmann

----------------------------------------------------------------
Sven Eckelmann (2):
      batman-adv: Use explicit tvlv padding for ELP packets
      batman-adv: Expand merged fragment buffer for full packet

 net/batman-adv/bat_v_elp.c     | 6 ++++--
 net/batman-adv/fragmentation.c | 2 +-
 2 files changed, 5 insertions(+), 3 deletions(-)

[PATCH 1/2] batman-adv: Use explicit tvlv padding for ELP packets

[Simon Wunderlich]

From: Sven Eckelmann <sven-KaDOiPu9UxWEi8DpZVb4nw@public.gmane.org>

The announcement messages of batman-adv COMPAT_VERSION 15 have the
possibility to announce additional information via a dynamic TVLV part.
This part is optional for the ELP packets and currently not parsed by the
Linux implementation. Still out-of-tree versions are using it to transport
things like neighbor hashes to optimize the rebroadcast behavior.

Since the ELP broadcast packets are smaller than the minimal ethernet
packet, it often has to be padded. This is often done (as specified in
RFC894) with octets of zero and thus work perfectly fine with the TVLV
part (making it a zero length and thus empty). But not all ethernet
compatible hardware seems to follow this advice. To avoid ambiguous
situations when parsing the TVLV header, just force the 4 bytes (TVLV
length + padding) after the required ELP header to zero.

Fixes: d6f94d91f766 ("batman-adv: ELP - adding basic infrastructure")
Reported-by: Linus Lüssing <linus.luessing-djzkFPsfvsizQB+pC5nmwQ@public.gmane.org>
Signed-off-by: Sven Eckelmann <sven-KaDOiPu9UxWEi8DpZVb4nw@public.gmane.org>
Signed-off-by: Simon Wunderlich <sw-2YrNx6rUIHYiY0qSoAWiAoQuADTiUCJX@public.gmane.org>
---
 net/batman-adv/bat_v_elp.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/batman-adv/bat_v_elp.c b/net/batman-adv/bat_v_elp.c
index 9f481cfdf77d..e8090f099eb8 100644
--- a/net/batman-adv/bat_v_elp.c
+++ b/net/batman-adv/bat_v_elp.c
@@ -352,19 +352,21 @@ static void batadv_v_elp_periodic_work(struct work_struct *work)
  */
 int batadv_v_elp_iface_enable(struct batadv_hard_iface *hard_iface)
 {
+	static const size_t tvlv_padding = sizeof(__be32);
 	struct batadv_elp_packet *elp_packet;
 	unsigned char *elp_buff;
 	u32 random_seqno;
 	size_t size;
 	int res = -ENOMEM;
 
-	size = ETH_HLEN + NET_IP_ALIGN + BATADV_ELP_HLEN;
+	size = ETH_HLEN + NET_IP_ALIGN + BATADV_ELP_HLEN + tvlv_padding;
 	hard_iface->bat_v.elp_skb = dev_alloc_skb(size);
 	if (!hard_iface->bat_v.elp_skb)
 		goto out;
 
 	skb_reserve(hard_iface->bat_v.elp_skb, ETH_HLEN + NET_IP_ALIGN);
-	elp_buff = skb_put_zero(hard_iface->bat_v.elp_skb, BATADV_ELP_HLEN);
+	elp_buff = skb_put_zero(hard_iface->bat_v.elp_skb,
+				BATADV_ELP_HLEN + tvlv_padding);
 	elp_packet = (struct batadv_elp_packet *)elp_buff;
 
 	elp_packet->packet_type = BATADV_ELP;
-- 
2.11.0

[PATCH 2/2] batman-adv: Expand merged fragment buffer for full packet

[Simon Wunderlich]

From: Sven Eckelmann <sven-KaDOiPu9UxWEi8DpZVb4nw@public.gmane.org>

The complete size ("total_size") of the fragmented packet is stored in the
fragment header and in the size of the fragment chain. When the fragments
are ready for merge, the skbuff's tail of the first fragment is expanded to
have enough room after the data pointer for at least total_size. This means
that it gets expanded by total_size - first_skb->len.

But this is ignoring the fact that after expanding the buffer, the fragment
header is pulled by from this buffer. Assuming that the tailroom of the
buffer was already 0, the buffer after the data pointer of the skbuff is
now only total_size - len(fragment_header) large. When the merge function
is then processing the remaining fragments, the code to copy the data over
to the merged skbuff will cause an skb_over_panic when it tries to actually
put enough data to fill the total_size bytes of the packet.

The size of the skb_pull must therefore also be taken into account when the
buffer's tailroom is expanded.

Fixes: 610bfc6bc99b ("batman-adv: Receive fragmented packets and merge")
Reported-by: Martin Weinelt <martin-VjL1Zewfs7ir2odhgoY7gCae+QG6wtwz@public.gmane.org>
Co-authored-by: Linus Lüssing <linus.luessing-djzkFPsfvsizQB+pC5nmwQ@public.gmane.org>
Signed-off-by: Sven Eckelmann <sven-KaDOiPu9UxWEi8DpZVb4nw@public.gmane.org>
Signed-off-by: Simon Wunderlich <sw-2YrNx6rUIHYiY0qSoAWiAoQuADTiUCJX@public.gmane.org>
---
 net/batman-adv/fragmentation.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/batman-adv/fragmentation.c b/net/batman-adv/fragmentation.c
index 0fddc17106bd..5b71a289d04f 100644
--- a/net/batman-adv/fragmentation.c
+++ b/net/batman-adv/fragmentation.c
@@ -275,7 +275,7 @@ batadv_frag_merge_packets(struct hlist_head *chain)
 	kfree(entry);
 
 	packet = (struct batadv_frag_packet *)skb_out->data;
-	size = ntohs(packet->total_size);
+	size = ntohs(packet->total_size) + hdr_size;
 
 	/* Make room for the rest of the fragments. */
 	if (pskb_expand_head(skb_out, 0, size - skb_out->len, GFP_ATOMIC) < 0) {
-- 
2.11.0

Re: [PATCH 0/2] pull request for net: batman-adv 2018-11-14

[David Miller]

From: Simon Wunderlich <sw@simonwunderlich.de>
Date: Wed, 14 Nov 2018 14:46:16 +0100

> here are some bugfixes which we would like to see integrated into net.
> 
> Please pull or let me know of any problem!

Pulled, thanks Simon.