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Message-Id: <ef8be9a1431875a6bce84dd07149c6e8eb874403.1617885385.git.lorenzo@kernel.org>
Date: Thu, 8 Apr 2021 14:51:02 +0200
From: Lorenzo Bianconi <lorenzo@...nel.org>
To: bpf@...r.kernel.org, netdev@...r.kernel.org
Cc: lorenzo.bianconi@...hat.com, davem@...emloft.net, kuba@...nel.org,
ast@...nel.org, daniel@...earbox.net, shayagr@...zon.com,
sameehj@...zon.com, john.fastabend@...il.com, dsahern@...nel.org,
brouer@...hat.com, echaudro@...hat.com, jasowang@...hat.com,
alexander.duyck@...il.com, saeed@...nel.org,
maciej.fijalkowski@...el.com
Subject: [PATCH v8 bpf-next 10/14] bpf: add new frame_length field to the XDP ctx
From: Eelco Chaudron <echaudro@...hat.com>
This patch adds a new field to the XDP context called frame_length,
which will hold the full length of the packet, including fragments
if existing.
eBPF programs can determine if fragments are present using something
like:
if (ctx->data_end - ctx->data < ctx->frame_length) {
/* Fragements exists. /*
}
Signed-off-by: Eelco Chaudron <echaudro@...hat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
---
include/linux/filter.h | 7 +++++++
include/net/xdp.h | 15 +++++++++++++++
include/uapi/linux/bpf.h | 1 +
net/core/filter.c | 8 ++++++++
net/core/xdp.c | 1 +
tools/include/uapi/linux/bpf.h | 1 +
6 files changed, 33 insertions(+)
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 9a09547bc7ba..d378a448f673 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -768,6 +768,13 @@ static __always_inline u32 bpf_prog_run_xdp(const struct bpf_prog *prog,
* already takes rcu_read_lock() when fetching the program, so
* it's not necessary here anymore.
*/
+ xdp->frame_length = xdp->data_end - xdp->data;
+ if (unlikely(xdp->mb)) {
+ struct xdp_shared_info *xdp_sinfo;
+
+ xdp_sinfo = xdp_get_shared_info_from_buff(xdp);
+ xdp->frame_length += xdp_sinfo->data_length;
+ }
return __BPF_PROG_RUN(prog, xdp, BPF_DISPATCHER_FUNC(xdp));
}
diff --git a/include/net/xdp.h b/include/net/xdp.h
index 55751cf2badf..e41022894770 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -77,6 +77,13 @@ struct xdp_buff {
* tailroom
*/
u32 mb:1; /* xdp non-linear buffer */
+ u32 frame_length; /* Total frame length across all buffers. Only needs
+ * to be updated by helper functions, as it will be
+ * initialized at XDP program start. This field only
+ * needs 17-bits (128kB). In case the remaining bits
+ * need to be re-purposed, please make sure the
+ * xdp_convert_ctx_access() function gets updated.
+ */
};
static __always_inline void
@@ -237,6 +244,14 @@ void xdp_convert_frame_to_buff(struct xdp_frame *frame, struct xdp_buff *xdp)
xdp->data_meta = frame->data - frame->metasize;
xdp->frame_sz = frame->frame_sz;
xdp->mb = frame->mb;
+ xdp->frame_length = frame->len;
+
+ if (unlikely(xdp->mb)) {
+ struct xdp_shared_info *xdp_sinfo;
+
+ xdp_sinfo = xdp_get_shared_info_from_buff(xdp);
+ xdp->frame_length += xdp_sinfo->data_length;
+ }
}
static inline
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 49371eba98ba..643ef5979d42 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5224,6 +5224,7 @@ struct xdp_md {
__u32 rx_queue_index; /* rxq->queue_index */
__u32 egress_ifindex; /* txq->dev->ifindex */
+ __u32 frame_length;
};
/* DEVMAP map-value layout
diff --git a/net/core/filter.c b/net/core/filter.c
index c00f52ab2532..8f8613745f0e 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3873,6 +3873,7 @@ static int bpf_xdp_mb_adjust_tail(struct xdp_buff *xdp, int offset)
memset(xdp_get_frag_address(frag) + size, 0, offset);
xdp_set_frag_size(frag, size + offset);
xdp_sinfo->data_length += offset;
+ xdp->frame_length += offset;
} else {
int i, frags_to_free = 0;
@@ -3894,6 +3895,7 @@ static int bpf_xdp_mb_adjust_tail(struct xdp_buff *xdp, int offset)
* to adjust the data_length in line.
*/
xdp_sinfo->data_length -= shrink;
+ xdp->frame_length -= shrink;
xdp_set_frag_size(frag, size - shrink);
break;
}
@@ -9137,6 +9139,12 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type type,
*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,
offsetof(struct net_device, ifindex));
break;
+ case offsetof(struct xdp_md, frame_length):
+ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct xdp_buff,
+ frame_length),
+ si->dst_reg, si->src_reg,
+ offsetof(struct xdp_buff, frame_length));
+ break;
}
return insn - insn_buf;
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 7388bc6d680b..fb7d0724a5b6 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -510,6 +510,7 @@ void xdp_return_num_frags_from_buff(struct xdp_buff *xdp, u16 num_frags)
struct page *page = xdp_get_frag_page(frag);
xdp_sinfo->data_length -= xdp_get_frag_size(frag);
+ xdp->frame_length -= xdp_get_frag_size(frag);
__xdp_return(page_address(page), &xdp->rxq->mem, false, NULL);
}
xdp_sinfo->nr_frags -= num_frags;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 69902603012c..5c2a497bfcf1 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5218,6 +5218,7 @@ struct xdp_md {
__u32 rx_queue_index; /* rxq->queue_index */
__u32 egress_ifindex; /* txq->dev->ifindex */
+ __u32 frame_length;
};
/* DEVMAP map-value layout
--
2.30.2
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