From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
To: netdev@vger.kernel.org
Cc: ast@kernel.org, daniel@iogearbox.net, sdf@google.com,
posk@google.com, Willem de Bruijn <willemb@google.com>
Subject: [PATCH bpf-next 08/13] bpf: add bpf_skb_adjust_room flag BPF_F_ADJ_ROOM_FIXED_GSO
Date: Wed, 20 Mar 2019 10:49:39 -0400 [thread overview]
Message-ID: <20190320144944.147862-9-willemdebruijn.kernel@gmail.com> (raw)
In-Reply-To: <20190320144944.147862-1-willemdebruijn.kernel@gmail.com>
From: Willem de Bruijn <willemb@google.com>
bpf_skb_adjust_room adjusts gso_size of gso packets to account for the
pushed or popped header room.
This is not allowed with UDP, where gso_size delineates datagrams. Add
an option to avoid these updates and allow this call for datagrams.
It can also be used with TCP, when MSS is known to allow headroom,
e.g., through MSS clamping or route MTU.
Link: https://patchwork.ozlabs.org/patch/1052497/
Signed-off-by: Willem de Bruijn <willemb@google.com>
---
include/uapi/linux/bpf.h | 4 ++++
net/core/filter.c | 36 +++++++++++++++++++++++++-----------
2 files changed, 29 insertions(+), 11 deletions(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 4f5c918e6fcf4..0eda8f564a381 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -2593,6 +2593,10 @@ enum bpf_func_id {
/* Current network namespace */
#define BPF_F_CURRENT_NETNS (-1L)
+/* BPF_FUNC_skb_adjust_room flags. */
+#define BPF_F_ADJ_ROOM_FIXED_GSO (1ULL << 0)
+#define BPF_F_ADJ_ROOM_MASK (BPF_F_ADJ_ROOM_FIXED_GSO)
+
/* Mode for BPF_FUNC_skb_adjust_room helper. */
enum bpf_adj_room_mode {
BPF_ADJ_ROOM_NET,
diff --git a/net/core/filter.c b/net/core/filter.c
index 1a0cf578b4502..e346e48098000 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2963,12 +2963,17 @@ static u32 bpf_skb_net_base_len(const struct sk_buff *skb)
}
}
-static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff)
+static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff,
+ u64 flags)
{
int ret;
- if (skb_is_gso(skb) && !skb_is_gso_tcp(skb))
- return -ENOTSUPP;
+ if (skb_is_gso(skb) && !skb_is_gso_tcp(skb)) {
+ /* udp gso_size delineates datagrams, only allow if fixed */
+ if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) ||
+ !(flags & BPF_F_ADJ_ROOM_FIXED_GSO))
+ return -ENOTSUPP;
+ }
ret = skb_cow_head(skb, len_diff);
if (unlikely(ret < 0))
@@ -2982,7 +2987,9 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff)
struct skb_shared_info *shinfo = skb_shinfo(skb);
/* Due to header grow, MSS needs to be downgraded. */
- skb_decrease_gso_size(shinfo, len_diff);
+ if (!(flags & BPF_F_ADJ_ROOM_FIXED_GSO))
+ skb_decrease_gso_size(shinfo, len_diff);
+
/* Header must be checked, and gso_segs recomputed. */
shinfo->gso_type |= SKB_GSO_DODGY;
shinfo->gso_segs = 0;
@@ -2991,12 +2998,17 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff)
return 0;
}
-static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff)
+static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff,
+ u64 flags)
{
int ret;
- if (skb_is_gso(skb) && !skb_is_gso_tcp(skb))
- return -ENOTSUPP;
+ if (skb_is_gso(skb) && !skb_is_gso_tcp(skb)) {
+ /* udp gso_size delineates datagrams, only allow if fixed */
+ if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) ||
+ !(flags & BPF_F_ADJ_ROOM_FIXED_GSO))
+ return -ENOTSUPP;
+ }
ret = skb_unclone(skb, GFP_ATOMIC);
if (unlikely(ret < 0))
@@ -3010,7 +3022,9 @@ static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff)
struct skb_shared_info *shinfo = skb_shinfo(skb);
/* Due to header shrink, MSS can be upgraded. */
- skb_increase_gso_size(shinfo, len_diff);
+ if (!(flags & BPF_F_ADJ_ROOM_FIXED_GSO))
+ 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;
@@ -3037,7 +3051,7 @@ BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff,
u32 off;
int ret;
- if (unlikely(flags))
+ if (unlikely(flags & ~BPF_F_ADJ_ROOM_MASK))
return -EINVAL;
if (unlikely(len_diff_abs > 0xfffU))
return -EFAULT;
@@ -3065,8 +3079,8 @@ BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff,
!skb_is_gso(skb))))
return -ENOTSUPP;
- ret = shrink ? bpf_skb_net_shrink(skb, off, len_diff_abs) :
- bpf_skb_net_grow(skb, off, len_diff_abs);
+ ret = shrink ? bpf_skb_net_shrink(skb, off, len_diff_abs, flags) :
+ bpf_skb_net_grow(skb, off, len_diff_abs, flags);
bpf_compute_data_pointers(skb);
return ret;
--
2.21.0.225.g810b269d1ac-goog
next prev parent reply other threads:[~2019-03-20 14:50 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-20 14:49 [PATCH bpf-next 00/13] bpf tc tunneling Willem de Bruijn
2019-03-20 14:49 ` [PATCH bpf-next 01/13] bpf: in bpf_skb_adjust_room avoid copy in tx fast path Willem de Bruijn
2019-03-20 14:49 ` [PATCH bpf-next 02/13] selftests/bpf: bpf tunnel encap test Willem de Bruijn
2019-03-20 14:49 ` [PATCH bpf-next 03/13] selftests/bpf: expand bpf tunnel test with decap Willem de Bruijn
2019-03-20 14:49 ` [PATCH bpf-next 04/13] selftests/bpf: expand bpf tunnel test to ipv6 Willem de Bruijn
2019-03-20 14:49 ` [PATCH bpf-next 05/13] selftests/bpf: extend bpf tunnel test with gre Willem de Bruijn
2019-03-20 14:49 ` [PATCH bpf-next 06/13] selftests/bpf: extend bpf tunnel test with tso Willem de Bruijn
2019-03-20 14:49 ` [PATCH bpf-next 07/13] bpf: add bpf_skb_adjust_room mode BPF_ADJ_ROOM_MAC Willem de Bruijn
2019-03-20 14:49 ` Willem de Bruijn [this message]
2019-03-21 13:42 ` [PATCH bpf-next 08/13] bpf: add bpf_skb_adjust_room flag BPF_F_ADJ_ROOM_FIXED_GSO Alan Maguire
2019-03-21 14:00 ` Willem de Bruijn
2019-03-20 14:49 ` [PATCH bpf-next 09/13] bpf: add bpf_skb_adjust_room encap flags Willem de Bruijn
2019-03-20 15:51 ` Alan Maguire
2019-03-20 18:10 ` Willem de Bruijn
2019-03-21 3:13 ` Alexei Starovoitov
2019-03-21 13:25 ` Willem de Bruijn
2019-03-20 14:49 ` [PATCH bpf-next 10/13] bpf: Sync bpf.h to tools Willem de Bruijn
2019-03-20 14:56 ` Soheil Hassas Yeganeh
2019-03-20 14:49 ` [PATCH bpf-next 11/13] selftests/bpf: convert bpf tunnel test to BPF_ADJ_ROOM_MAC Willem de Bruijn
2019-03-20 14:49 ` [PATCH bpf-next 12/13] selftests/bpf: convert bpf tunnel test to BPF_F_ADJ_ROOM_FIXED_GSO Willem de Bruijn
2019-03-20 14:49 ` [PATCH bpf-next 13/13] selftests/bpf: convert bpf tunnel test to encap modes Willem de Bruijn
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