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Message-Id: <20170412110726.9689-1-johannes@sipsolutions.net>
Date: Wed, 12 Apr 2017 13:07:24 +0200
From: Johannes Berg <johannes@...solutions.net>
To: linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Cc: Johannes Berg <johannes.berg@...el.com>
Subject: [RFC 1/3] bpf/wireless: add wifimon program type
From: Johannes Berg <johannes.berg@...el.com>
Add a new program type for wifi monitor interfaces. This program
type can
* access __sk_buff, but only skb->len
* call bpf_skb_load_bytes()
The program type is only enabled when something selects the new
Kconfig symbol WANT_BPF_WIFIMON, which will be done by mac80211
in a follow-up patch.
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
---
include/linux/bpf_types.h | 3 +++
include/uapi/linux/bpf.h | 1 +
net/core/filter.c | 41 +++++++++++++++++++++++++++++++++++++++++
net/wireless/Kconfig | 8 ++++++++
4 files changed, 53 insertions(+)
diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
index 03bf223f18be..fcaba84128dd 100644
--- a/include/linux/bpf_types.h
+++ b/include/linux/bpf_types.h
@@ -16,6 +16,9 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_KPROBE, kprobe_prog_ops)
BPF_PROG_TYPE(BPF_PROG_TYPE_TRACEPOINT, tracepoint_prog_ops)
BPF_PROG_TYPE(BPF_PROG_TYPE_PERF_EVENT, perf_event_prog_ops)
#endif
+#ifdef CONFIG_BPF_WIFIMON
+BPF_PROG_TYPE(BPF_PROG_TYPE_WIFIMON, wifimon_prog_ops)
+#endif
BPF_MAP_TYPE(BPF_MAP_TYPE_ARRAY, array_map_ops)
BPF_MAP_TYPE(BPF_MAP_TYPE_PERCPU_ARRAY, percpu_array_map_ops)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 1e062bb54eec..b0dfe8a79b3f 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -115,6 +115,7 @@ enum bpf_prog_type {
BPF_PROG_TYPE_LWT_IN,
BPF_PROG_TYPE_LWT_OUT,
BPF_PROG_TYPE_LWT_XMIT,
+ BPF_PROG_TYPE_WIFIMON,
};
enum bpf_attach_type {
diff --git a/net/core/filter.c b/net/core/filter.c
index ce2a19da8aa4..c20624c81f6b 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3415,3 +3415,44 @@ int sk_get_filter(struct sock *sk, struct sock_filter __user *ubuf,
release_sock(sk);
return ret;
}
+
+#ifdef CONFIG_BPF_WIFIMON
+static const struct bpf_func_proto *
+wifimon_func_proto(enum bpf_func_id func_id)
+{
+ switch (func_id) {
+ case BPF_FUNC_skb_load_bytes:
+ return &bpf_skb_load_bytes_proto;
+ default:
+ return bpf_base_func_proto(func_id);
+ }
+}
+
+static bool wifimon_is_valid_access(int off, int size,
+ enum bpf_access_type type,
+ enum bpf_reg_type *reg_type)
+{
+ if (type == BPF_WRITE)
+ return false;
+
+ switch (off) {
+ case offsetof(struct __sk_buff, len):
+ break;
+ default:
+ return false;
+ }
+ /* The verifier guarantees that size > 0. */
+ if (off % size != 0)
+ return false;
+ if (size != sizeof(__u32))
+ return false;
+
+ return true;
+}
+
+const struct bpf_verifier_ops wifimon_prog_ops = {
+ .get_func_proto = wifimon_func_proto,
+ .is_valid_access = wifimon_is_valid_access,
+ .convert_ctx_access = bpf_convert_ctx_access,
+};
+#endif
diff --git a/net/wireless/Kconfig b/net/wireless/Kconfig
index 6c606120abfe..50ffebafce46 100644
--- a/net/wireless/Kconfig
+++ b/net/wireless/Kconfig
@@ -214,3 +214,11 @@ config LIB80211_DEBUG
from lib80211.
If unsure, say N.
+
+config WANT_BPF_WIFIMON
+ bool
+
+config BPF_WIFIMON
+ bool
+ default y
+ depends on WANT_BPF_WIFIMON && BPF_SYSCALL
--
2.11.0
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