netdev - [PATCH bpf-next v3 07/11] bpf: make tun compatible w/ bpf_xdp_adjust

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 17 Apr 2018 21:42:19 -0700
From:   "Nikita V. Shirokov" <tehnerd@...nerd.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jason Wang <jasowang@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        "Michael S. Tsirkin" <mst@...hat.com>
Cc:     netdev@...r.kernel.org, "Nikita V. Shirokov" <tehnerd@...nerd.com>
Subject: [PATCH bpf-next v3 07/11] bpf: make tun compatible w/ bpf_xdp_adjust_tail

w/ bpf_xdp_adjust_tail helper xdp's data_end pointer could be changed as
well (only "decrease" of pointer's location is going to be supported).
changing of this pointer will change packet's size.
for tun driver we need to adjust XDP_PASS handling by recalculating
length of the packet if it was passed to the TCP/IP stack
(in case if after xdp's prog run data_end pointer was adjusted)

Reviewed-by: Jason Wang <jasowang@...hat.com>
Signed-off-by: Nikita V. Shirokov <tehnerd@...nerd.com>
---
 drivers/net/tun.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 1e58be152d5c..901351a6ed21 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1696,6 +1696,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
 			return NULL;
 		case XDP_PASS:
 			delta = orig_data - xdp.data;
+			len = xdp.data_end - xdp.data;
 			break;
 		default:
 			bpf_warn_invalid_xdp_action(act);
@@ -1716,7 +1717,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
 	}
 
 	skb_reserve(skb, pad - delta);
-	skb_put(skb, len + delta);
+	skb_put(skb, len);
 	get_page(alloc_frag->page);
 	alloc_frag->offset += buflen;
 
-- 
2.15.1