From: Vasily Averin <vvs@virtuozzo.com>
To: "David S. Miller" <davem@davemloft.net>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
David Ahern <dsahern@kernel.org>,
Jakub Kicinski <kuba@kernel.org>,
Eric Dumazet <eric.dumazet@gmail.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH IPV6 v2 1/4] ipv6: allocate enough headroom in ip6_finish_output2()
Date: Fri, 9 Jul 2021 12:04:45 +0300 [thread overview]
Message-ID: <4f6a2b28-a137-2e19-bf62-5a8767d0d0ac@virtuozzo.com> (raw)
In-Reply-To: <cover.1625818825.git.vvs@virtuozzo.com>
When TEE target mirrors traffic to another interface, sk_buff may
not have enough headroom to be processed correctly.
ip_finish_output2() detect this situation for ipv4 and allocates
new skb with enogh headroom. However ipv6 lacks this logic in
ip_finish_output2 and it leads to skb_under_panic:
skbuff: skb_under_panic: text:ffffffffc0866ad4 len:96 put:24
head:ffff97be85e31800 data:ffff97be85e317f8 tail:0x58 end:0xc0 dev:gre0
------------[ cut here ]------------
kernel BUG at net/core/skbuff.c:110!
invalid opcode: 0000 [#1] SMP PTI
CPU: 2 PID: 393 Comm: kworker/2:2 Tainted: G OE 5.13.0 #13
Hardware name: Virtuozzo KVM, BIOS 1.11.0-2.vz7.4 04/01/2014
Workqueue: ipv6_addrconf addrconf_dad_work
RIP: 0010:skb_panic+0x48/0x4a
Call Trace:
skb_push.cold.111+0x10/0x10
ipgre_header+0x24/0xf0 [ip_gre]
neigh_connected_output+0xae/0xf0
ip6_finish_output2+0x1a8/0x5a0
ip6_output+0x5c/0x110
nf_dup_ipv6+0x158/0x1000 [nf_dup_ipv6]
tee_tg6+0x2e/0x40 [xt_TEE]
ip6t_do_table+0x294/0x470 [ip6_tables]
nf_hook_slow+0x44/0xc0
nf_hook.constprop.34+0x72/0xe0
ndisc_send_skb+0x20d/0x2e0
ndisc_send_ns+0xd1/0x210
addrconf_dad_work+0x3c8/0x540
process_one_work+0x1d1/0x370
worker_thread+0x30/0x390
kthread+0x116/0x130
ret_from_fork+0x22/0x30
This patch implement new helper that tries to expand headroom on current skb,
if it is not possible (shared_skb) -- creates new one.
v2 open questions:
- currently helper name skb_expand_head is bad
and should be changed to better one. Any suggestions?
- proper location for new helper:
in net/core/skbuff.c right below skb_realloc_headroom() ?
- is it acceptable to free original skb inside helper ?
Is it probably required to keep it in caller instead?
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
---
net/ipv6/ip6_output.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index ff4f9eb..6c5f85f 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -56,14 +56,48 @@
#include <net/lwtunnel.h>
#include <net/ip_tunnels.h>
+static inline struct sk_buff *skb_expand_head(struct sk_buff *skb, int delta)
+{
+ /* pskb_expand_head() might crash, if skb is shared */
+ if (skb_shared(skb)) {
+ struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
+
+ if (likely(nskb)) {
+ if (skb->sk)
+ skb_set_owner_w(skb, skb->sk);
+ consume_skb(skb);
+ } else {
+ kfree_skb(skb);
+ }
+ skb = nskb;
+ }
+ if (skb &&
+ pskb_expand_head(skb, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC)) {
+ kfree_skb(skb);
+ skb = NULL;
+ }
+ return skb;
+}
+
static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
{
struct dst_entry *dst = skb_dst(skb);
struct net_device *dev = dst->dev;
+ unsigned int hh_len = LL_RESERVED_SPACE(dev);
+ int delta = hh_len - skb_headroom(skb);
const struct in6_addr *nexthop;
struct neighbour *neigh;
int ret;
+ /* Be paranoid, rather than too clever. */
+ if (unlikely(delta > 0) && dev->header_ops)
+ skb = skb_expand_head(skb, delta);
+
+ if (!skb) {
+ IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTDISCARDS);
+ return -ENOMEM;
+ }
+
if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr)) {
struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));
--
1.8.3.1
next prev parent reply other threads:[~2021-07-09 9:04 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1625665132.git.vvs@virtuozzo.com>
2021-07-07 14:04 ` [PATCH IPV6 1/1] ipv6: allocate enough headroom in ip6_finish_output2() Vasily Averin
2021-07-07 14:45 ` David Ahern
2021-07-07 16:42 ` Jakub Kicinski
2021-07-07 17:41 ` Eric Dumazet
2021-07-07 17:53 ` Vasily Averin
2021-07-07 18:30 ` Jakub Kicinski
2021-07-07 18:50 ` Eric Dumazet
2021-07-09 9:04 ` [PATCH IPV6 v2 0/4] " Vasily Averin
2021-07-12 6:44 ` [PATCH IPV6 v3 0/1] " Vasily Averin
[not found] ` <cover.1626069562.git.vvs@virtuozzo.com>
2021-07-12 6:45 ` [PATCH IPV6 v3 1/1] " Vasily Averin
2021-07-12 18:30 ` patchwork-bot+netdevbpf
2021-07-13 7:46 ` Vasily Averin
2021-07-13 12:01 ` [PATCH NET v4 0/1] " Vasily Averin
[not found] ` <cover.1626177047.git.vvs@virtuozzo.com>
2021-07-13 12:01 ` [PATCH NET v4 1/1] " Vasily Averin
2021-07-18 10:44 ` Vasily Averin
2021-07-18 15:22 ` David Ahern
2021-07-18 17:04 ` David Miller
2021-07-19 7:55 ` [PATCH NET] ipv6: ip6_finish_output2: set sk into newly allocated nskb Vasily Averin
2021-07-20 10:10 ` patchwork-bot+netdevbpf
2021-07-13 12:31 ` [PATCH IPV6 v3 1/1] ipv6: allocate enough headroom in ip6_finish_output2() Vasily Averin
2021-07-12 13:26 ` [PATCH NET 0/7] skbuff: introduce pskb_realloc_headroom() Vasily Averin
[not found] ` <cover.1626093470.git.vvs@virtuozzo.com>
2021-07-12 13:26 ` [PATCH NET 1/7] " Vasily Averin
2021-07-12 17:53 ` Jakub Kicinski
2021-07-12 18:45 ` Vasily Averin
2021-07-13 20:57 ` [PATCH NET v2 0/7] skbuff: introduce skb_expand_head() Vasily Averin
2021-08-02 8:52 ` [PATCH NET v3 " Vasily Averin
[not found] ` <cover.1627891754.git.vvs@virtuozzo.com>
2021-08-02 8:52 ` [PATCH NET v3 1/7] " Vasily Averin
2021-08-02 8:52 ` [PATCH NET v3 2/7] ipv6: use skb_expand_head in ip6_finish_output2 Vasily Averin
2021-08-02 8:52 ` [PATCH NET v3 3/7] ipv6: use skb_expand_head in ip6_xmit Vasily Averin
2021-08-02 8:52 ` [PATCH NET v3 4/7] ipv4: use skb_expand_head in ip_finish_output2 Vasily Averin
2021-08-02 8:52 ` [PATCH NET v3 5/7] vrf: use skb_expand_head in vrf_finish_output Vasily Averin
2021-08-05 11:55 ` Julian Wiedmann
2021-08-05 12:55 ` Vasily Averin
2021-08-06 7:49 ` [PATCH NET v4 0/7] skbuff: introduce skb_expand_head() Vasily Averin
2021-08-06 10:14 ` David Miller
2021-08-06 12:53 ` [PATCH NET] vrf: fix null pointer dereference in vrf_finish_output() Vasily Averin
2021-08-06 22:42 ` Jakub Kicinski
2021-08-07 6:41 ` Vasily Averin
[not found] ` <cover.1628235065.git.vvs@virtuozzo.com>
2021-08-06 7:49 ` [PATCH NET v4 1/7] skbuff: introduce skb_expand_head() Vasily Averin
2021-08-06 7:50 ` [PATCH NET v4 2/7] ipv6: use skb_expand_head in ip6_finish_output2 Vasily Averin
2021-08-06 7:50 ` [PATCH NET v4 3/7] ipv6: use skb_expand_head in ip6_xmit Vasily Averin
[not found] ` <CALMXkpaay1y=0tkbnskr4gf-HTMjJJsVryh4Prnej_ws-hJvBg@mail.gmail.com>
2021-08-20 22:44 ` Christoph Paasch
2021-08-21 6:21 ` Vasily Averin
2021-08-22 17:04 ` Christoph Paasch
2021-08-22 17:13 ` Christoph Paasch
2021-08-23 5:44 ` Vasily Averin
2021-08-23 5:59 ` Vasily Averin
2021-08-23 7:56 ` [PATCH NET-NEXT] ipv6: skb_expand_head() adjust skb->truesize incorrectly Vasily Averin
2021-08-23 17:25 ` Christoph Paasch
2021-08-23 21:45 ` Eric Dumazet
2021-08-23 21:51 ` Eric Dumazet
2021-08-23 22:23 ` Eric Dumazet
2021-08-24 8:50 ` Vasily Averin
2021-08-24 17:21 ` Vasily Averin
2021-08-25 17:49 ` Christoph Paasch
2021-08-29 12:59 ` [PATCH v2] " Vasily Averin
2021-08-30 5:52 ` [PATCH net-next " Vasily Averin
2021-08-30 16:01 ` [PATCH " Eric Dumazet
2021-08-30 18:09 ` Vasily Averin
2021-08-30 18:37 ` Vasily Averin
2021-08-30 19:58 ` Eric Dumazet
2021-08-31 14:34 ` [PATCH net-next v3 RFC] " Vasily Averin
2021-08-31 19:38 ` Eric Dumazet
2021-09-01 6:20 ` Vasily Averin
2021-09-01 8:11 ` [PATCH net-next v4] " Vasily Averin
2021-09-01 16:58 ` Christoph Paasch
2021-09-01 19:17 ` Eric Dumazet
2021-09-02 3:59 ` Vasily Averin
2021-09-02 4:32 ` Eric Dumazet
2021-09-02 4:48 ` Eric Dumazet
2021-09-02 7:13 ` Vasily Averin
2021-09-02 7:33 ` Vasily Averin
2021-09-02 8:31 ` Vasily Averin
2021-09-02 11:12 ` [PATCH net-next v5] " Vasily Averin
2021-09-02 15:53 ` Christoph Paasch
2021-09-02 16:32 ` Vasily Averin
2021-09-06 18:01 ` [PATCH net v6] " Vasily Averin
2021-09-06 18:03 ` Vasily Averin
2021-08-27 15:23 ` [PATCH NET-NEXT] ipv6: " Vasily Averin
2021-08-27 16:47 ` Eric Dumazet
2021-08-28 8:01 ` Vasily Averin
2021-08-06 7:50 ` [PATCH NET v4 4/7] ipv4: use skb_expand_head in ip_finish_output2 Vasily Averin
2021-08-06 7:50 ` [PATCH NET v4 5/7] vrf: use skb_expand_head in vrf_finish_output Vasily Averin
2021-08-06 7:50 ` [PATCH NET v4 6/7] ax25: use skb_expand_head Vasily Averin
2021-08-06 7:50 ` [PATCH NET v4 7/7] bpf: use skb_expand_head in bpf_out_neigh_v4/6 Vasily Averin
2021-08-02 8:52 ` [PATCH NET v3 6/7] ax25: use skb_expand_head Vasily Averin
2021-08-02 8:52 ` [PATCH NET v3 7/7] bpf: use skb_expand_head in bpf_out_neigh_v4/6 Vasily Averin
[not found] ` <cover.1626206993.git.vvs@virtuozzo.com>
2021-07-13 20:57 ` [PATCH NET v2 1/7] skbuff: introduce skb_expand_head() Vasily Averin
2021-07-13 20:58 ` [PATCH NET v2 2/7] ipv6: use skb_expand_head in ip6_finish_output2 Vasily Averin
2021-07-13 20:58 ` [PATCH NET v2 3/7] ipv6: use skb_expand_head in ip6_xmit Vasily Averin
2021-07-13 20:58 ` [PATCH NET v2 4/7] ipv4: use skb_expand_head in ip_finish_output2 Vasily Averin
2021-07-13 20:58 ` [PATCH NET v2 5/7] vrf: use skb_expand_head in vrf_finish_output Vasily Averin
2021-07-13 20:58 ` [PATCH NET v2 6/7] ax25: use skb_expand_head Vasily Averin
2021-07-13 20:58 ` [PATCH NET v2 7/7] bpf: use skb_expand_head in bpf_out_neigh_v4/6 Vasily Averin
2021-07-12 13:26 ` [PATCH NET 2/7] ipv6: use pskb_realloc_headroom in ip6_finish_output2 Vasily Averin
2021-07-12 13:26 ` [PATCH NET 3/7] ipv6: use pskb_realloc_headroom in ip6_xmit refactoring Vasily Averin
2021-07-12 13:27 ` [PATCH NET 4/7] ipv4: use pskb_realloc_headroom in ip_finish_output2 Vasily Averin
2021-07-12 13:27 ` [PATCH NET 5/7] vrf: use pskb_realloc_headroom in vrf_finish_output Vasily Averin
2021-07-12 13:27 ` [PATCH NET 6/7] ax25: use pskb_realloc_headroom Vasily Averin
2021-07-12 13:27 ` [PATCH NET 7/7] bpf: use pskb_realloc_headroom in bpf_out_neigh_v4/6 Vasily Averin
[not found] ` <cover.1625818825.git.vvs@virtuozzo.com>
2021-07-09 9:04 ` Vasily Averin [this message]
2021-07-09 17:58 ` [PATCH IPV6 v2 1/4] ipv6: allocate enough headroom in ip6_finish_output2() David Miller
2021-07-10 2:53 ` Vasily Averin
2021-07-09 9:04 ` [PATCH IPV6 v2 2/4] ipv6: use new helper skb_expand_head() in ip6_xmit() Vasily Averin
2021-07-09 9:05 ` [PATCH IPV6 v2 3/4] ipv6: ip6_finish_output2 refactoring Vasily Averin
2021-07-09 9:05 ` [PATCH IPV6 v2 4/4] ipv6: ip6_xmit refactoring Vasily Averin
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