lkml.org 
[lkml]   [2021]   [Apr]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH bpf] bpf: check for data_len before upgrading mss when 6 to 4
Date
tcp_gso_segment check for the size of GROed payload if it is bigger
than the mss. bpf_skb_proto_6_to_4 increases mss, but the mss can be
bigger than the size of GROed payload unexpectedly if data_len is not
big enough.

Assume that skb gso_size = 1372 and data_len = 8. bpf_skb_proto_6_to_4
would increse the gso_size to 1392. tcp_gso_segment will get an error
with 1380 <= 1392.

Check for the size of GROed payload if it is really bigger than target
mss when increase mss.

Fixes: 6578171a7ff0 (bpf: add bpf_skb_change_proto helper)
Signed-off-by: Dongseok Yi <dseok.yi@samsung.com>
---
net/core/filter.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index 9323d34..3f79e3c 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3308,7 +3308,9 @@ static int bpf_skb_proto_6_to_4(struct sk_buff *skb)
}

/* Due to IPv4 header, MSS can be upgraded. */
- skb_increase_gso_size(shinfo, len_diff);
+ if (skb->data_len > len_diff)
+ skb_increase_gso_size(shinfo, len_diff);
+
/* Header must be checked, and gso_segs recomputed. */
shinfo->gso_type |= SKB_GSO_DODGY;
shinfo->gso_segs = 0;
--
2.7.4
\
 
 \ /
  Last update: 2021-04-29 12:22    [W:0.201 / U:2.864 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site