* [PATCH] bpf: allow BPF programs access skb_shared_info->gso_segs field
@ 2018-07-15 8:45 Eddie Hao
2018-07-15 22:06 ` Eddie Hao
2018-07-16 22:30 ` Alexei Starovoitov
0 siblings, 2 replies; 3+ messages in thread
From: Eddie Hao @ 2018-07-15 8:45 UTC (permalink / raw)
To: ast, daniel; +Cc: davem, netdev, linux-kernel, Eddie Hao
This adds the ability to read gso_segs from a BPF program. This is useful
for user space monitoring systems to get gso_segs statistics for each
arbitrary group of flows defined by the BPF program.
Signed-off-by: Eddie Hao <eddieh@google.com>
---
include/uapi/linux/bpf.h | 1 +
net/core/filter.c | 9 +++++++++
2 files changed, 10 insertions(+)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index b7db3261c62d..282085445616 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -2266,6 +2266,7 @@ struct __sk_buff {
/* ... here. */
__u32 data_meta;
+ unsigned short gso_segs;
};
struct bpf_tunnel_key {
diff --git a/net/core/filter.c b/net/core/filter.c
index b9ec916f4e3a..f17e249f3fbb 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5820,6 +5820,15 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type,
bpf_target_off(struct sock_common,
skc_num, 2, target_size));
break;
+
+ case offsetof(struct __sk_buff, gso_segs):
+ BUILD_BUG_ON(FIELD_SIZEOF(struct skb_shared_info, gso_segs) !=
+ sizeof(unsigned short));
+ off = offsetof(struct sk_buff, end);
+ off += offsetof(struct skb_shared_info, gso_segs);
+ *insn++ = BPF_LDX_MEM(BPF_SIZEOF(unsigned short), si->dst_reg,
+ si->src_reg, off);
+ break;
}
return insn - insn_buf;
--
2.18.0.203.gfac676dfb9-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] bpf: allow BPF programs access skb_shared_info->gso_segs field
2018-07-15 8:45 [PATCH] bpf: allow BPF programs access skb_shared_info->gso_segs field Eddie Hao
@ 2018-07-15 22:06 ` Eddie Hao
2018-07-16 22:30 ` Alexei Starovoitov
1 sibling, 0 replies; 3+ messages in thread
From: Eddie Hao @ 2018-07-15 22:06 UTC (permalink / raw)
To: ast, daniel; +Cc: davem, netdev, linux-kernel
Sorry, forgot to annotate the subject line with bpf-next.
On Sun, Jul 15, 2018 at 1:45 AM Eddie Hao <eddieh@google.com> wrote:
>
> This adds the ability to read gso_segs from a BPF program. This is useful
> for user space monitoring systems to get gso_segs statistics for each
> arbitrary group of flows defined by the BPF program.
>
> Signed-off-by: Eddie Hao <eddieh@google.com>
> ---
> include/uapi/linux/bpf.h | 1 +
> net/core/filter.c | 9 +++++++++
> 2 files changed, 10 insertions(+)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index b7db3261c62d..282085445616 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -2266,6 +2266,7 @@ struct __sk_buff {
> /* ... here. */
>
> __u32 data_meta;
> + unsigned short gso_segs;
> };
>
> struct bpf_tunnel_key {
> diff --git a/net/core/filter.c b/net/core/filter.c
> index b9ec916f4e3a..f17e249f3fbb 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -5820,6 +5820,15 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type,
> bpf_target_off(struct sock_common,
> skc_num, 2, target_size));
> break;
> +
> + case offsetof(struct __sk_buff, gso_segs):
> + BUILD_BUG_ON(FIELD_SIZEOF(struct skb_shared_info, gso_segs) !=
> + sizeof(unsigned short));
> + off = offsetof(struct sk_buff, end);
> + off += offsetof(struct skb_shared_info, gso_segs);
> + *insn++ = BPF_LDX_MEM(BPF_SIZEOF(unsigned short), si->dst_reg,
> + si->src_reg, off);
> + break;
> }
>
> return insn - insn_buf;
> --
> 2.18.0.203.gfac676dfb9-goog
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] bpf: allow BPF programs access skb_shared_info->gso_segs field
2018-07-15 8:45 [PATCH] bpf: allow BPF programs access skb_shared_info->gso_segs field Eddie Hao
2018-07-15 22:06 ` Eddie Hao
@ 2018-07-16 22:30 ` Alexei Starovoitov
1 sibling, 0 replies; 3+ messages in thread
From: Alexei Starovoitov @ 2018-07-16 22:30 UTC (permalink / raw)
To: Eddie Hao; +Cc: ast, daniel, davem, netdev, linux-kernel
On Sun, Jul 15, 2018 at 01:45:24AM -0700, Eddie Hao wrote:
> This adds the ability to read gso_segs from a BPF program. This is useful
> for user space monitoring systems to get gso_segs statistics for each
> arbitrary group of flows defined by the BPF program.
>
> Signed-off-by: Eddie Hao <eddieh@google.com>
> ---
> include/uapi/linux/bpf.h | 1 +
> net/core/filter.c | 9 +++++++++
> 2 files changed, 10 insertions(+)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index b7db3261c62d..282085445616 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -2266,6 +2266,7 @@ struct __sk_buff {
> /* ... here. */
>
> __u32 data_meta;
> + unsigned short gso_segs;
'short' will make it harder to extend due to struct hole.
please use __u32 instead.
> };
>
> struct bpf_tunnel_key {
> diff --git a/net/core/filter.c b/net/core/filter.c
> index b9ec916f4e3a..f17e249f3fbb 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -5820,6 +5820,15 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type,
> bpf_target_off(struct sock_common,
> skc_num, 2, target_size));
> break;
> +
> + case offsetof(struct __sk_buff, gso_segs):
> + BUILD_BUG_ON(FIELD_SIZEOF(struct skb_shared_info, gso_segs) !=
> + sizeof(unsigned short));
> + off = offsetof(struct sk_buff, end);
> + off += offsetof(struct skb_shared_info, gso_segs);
did you test this patch?
Above math doesn't look correct.
NET_SKBUFF_DATA_USES_OFFSET is not handled. At least one more LDX is needed.
> + *insn++ = BPF_LDX_MEM(BPF_SIZEOF(unsigned short), si->dst_reg,
> + si->src_reg, off);
I think BUILD_BUG_ON is a bit of overkill when BPF_LDX_MEM
can use BPF_FIELD_SIZEOF(struct skb_shared_info, gso_segs) instead.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2018-07-15 8:45 [PATCH] bpf: allow BPF programs access skb_shared_info->gso_segs field Eddie Hao
2018-07-15 22:06 ` Eddie Hao
2018-07-16 22:30 ` Alexei Starovoitov
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