netdev - [PATCH v16 bpf-next 12/20] bpf: introduce bpf_xdp_get_buff

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]

Message-Id: <223a81d8b9080a7cd4c50c9f31081462a9a9d768.1634301224.git.lorenzo@kernel.org>
Date:   Fri, 15 Oct 2021 15:08:49 +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,
        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, magnus.karlsson@...el.com,
        tirthendu.sarkar@...el.com, toke@...hat.com
Subject: [PATCH v16 bpf-next 12/20] bpf: introduce bpf_xdp_get_buff_len helper

Introduce bpf_xdp_get_buff_len helper in order to return the xdp buffer
total size (linear and paged area)

Acked-by: John Fastabend <john.fastabend@...il.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
---
 include/uapi/linux/bpf.h       |  7 +++++++
 net/core/filter.c              | 23 +++++++++++++++++++++++
 tools/include/uapi/linux/bpf.h |  7 +++++++
 3 files changed, 37 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 87c10a90c243..1cb992ec0cc8 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4914,6 +4914,12 @@ union bpf_attr {
  *	Return
  *		The number of bytes written to the buffer, or a negative error
  *		in case of failure.
+ *
+ * u64 bpf_xdp_get_buff_len(struct xdp_buff *xdp_md)
+ *	Description
+ *		Get the total size of a given xdp buff (linear and paged area)
+ *	Return
+ *		The total size of a given xdp buffer.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -5094,6 +5100,7 @@ union bpf_attr {
 	FN(task_pt_regs),		\
 	FN(get_branch_snapshot),	\
 	FN(trace_vprintk),		\
+	FN(xdp_get_buff_len),		\
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/net/core/filter.c b/net/core/filter.c
index 02fc6aa8a7b6..1749374a3d04 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3784,6 +3784,27 @@ static const struct bpf_func_proto sk_skb_change_head_proto = {
 	.arg2_type	= ARG_ANYTHING,
 	.arg3_type	= ARG_ANYTHING,
 };
+
+BPF_CALL_1(bpf_xdp_get_buff_len, struct  xdp_buff*, xdp)
+{
+	u64 len = xdp->data_end - xdp->data;
+
+	if (unlikely(xdp_buff_is_mb(xdp))) {
+		struct skb_shared_info *sinfo;
+
+		sinfo = xdp_get_shared_info_from_buff(xdp);
+		len += sinfo->xdp_frags_size;
+	}
+	return len;
+}
+
+static const struct bpf_func_proto bpf_xdp_get_buff_len_proto = {
+	.func		= bpf_xdp_get_buff_len,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX,
+};
+
 static unsigned long xdp_get_metalen(const struct xdp_buff *xdp)
 {
 	return xdp_data_meta_unsupported(xdp) ? 0 :
@@ -7536,6 +7557,8 @@ xdp_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_xdp_redirect_map_proto;
 	case BPF_FUNC_xdp_adjust_tail:
 		return &bpf_xdp_adjust_tail_proto;
+	case BPF_FUNC_xdp_get_buff_len:
+		return &bpf_xdp_get_buff_len_proto;
 	case BPF_FUNC_fib_lookup:
 		return &bpf_xdp_fib_lookup_proto;
 	case BPF_FUNC_check_mtu:
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 87c10a90c243..1cb992ec0cc8 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -4914,6 +4914,12 @@ union bpf_attr {
  *	Return
  *		The number of bytes written to the buffer, or a negative error
  *		in case of failure.
+ *
+ * u64 bpf_xdp_get_buff_len(struct xdp_buff *xdp_md)
+ *	Description
+ *		Get the total size of a given xdp buff (linear and paged area)
+ *	Return
+ *		The total size of a given xdp buffer.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -5094,6 +5100,7 @@ union bpf_attr {
 	FN(task_pt_regs),		\
 	FN(get_branch_snapshot),	\
 	FN(trace_vprintk),		\
+	FN(xdp_get_buff_len),		\
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
-- 
2.31.1