linux-kernel - [PATCH bpf-next v3] bpf: Only provide bpf_sock_from_file with CONFIG

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Message-Id: <20201208173623.1136863-1-revest@chromium.org>
Date:   Tue,  8 Dec 2020 18:36:23 +0100
From:   Florent Revest <revest@...omium.org>
To:     bpf@...r.kernel.org
Cc:     ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
        kpsingh@...omium.org, rdunlap@...radead.org, kafai@...com,
        linux-next@...r.kernel.org, linux-kernel@...r.kernel.org,
        Florent Revest <revest@...omium.org>,
        kernel test robot <lkp@...el.com>
Subject: [PATCH bpf-next v3] bpf: Only provide bpf_sock_from_file with CONFIG_NET

This moves the bpf_sock_from_file definition into net/core/filter.c
which only gets compiled with CONFIG_NET and also moves the helper proto
usage next to other tracing helpers that are conditional on CONFIG_NET.

This avoids
  ld: kernel/trace/bpf_trace.o: in function `bpf_sock_from_file':
  bpf_trace.c:(.text+0xe23): undefined reference to `sock_from_file'
When compiling a kernel with BPF and without NET.

Reported-by: kernel test robot <lkp@...el.com>
Reported-by: Randy Dunlap <rdunlap@...radead.org>
Acked-by: Randy Dunlap <rdunlap@...radead.org>
Signed-off-by: Florent Revest <revest@...omium.org>
---
 include/linux/bpf.h      |  1 +
 kernel/trace/bpf_trace.c | 22 ++--------------------
 net/core/filter.c        | 18 ++++++++++++++++++
 3 files changed, 21 insertions(+), 20 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index d05e75ed8c1b..07cb5d15e743 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1859,6 +1859,7 @@ extern const struct bpf_func_proto bpf_snprintf_btf_proto;
 extern const struct bpf_func_proto bpf_per_cpu_ptr_proto;
 extern const struct bpf_func_proto bpf_this_cpu_ptr_proto;
 extern const struct bpf_func_proto bpf_ktime_get_coarse_ns_proto;
+extern const struct bpf_func_proto bpf_sock_from_file_proto;
 
 const struct bpf_func_proto *bpf_tracing_func_proto(
 	enum bpf_func_id func_id, const struct bpf_prog *prog);
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 0cf0a6331482..52ddd217d6a1 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1270,24 +1270,6 @@ const struct bpf_func_proto bpf_snprintf_btf_proto = {
 	.arg5_type	= ARG_ANYTHING,
 };
 
-BPF_CALL_1(bpf_sock_from_file, struct file *, file)
-{
-	return (unsigned long) sock_from_file(file);
-}
-
-BTF_ID_LIST(bpf_sock_from_file_btf_ids)
-BTF_ID(struct, socket)
-BTF_ID(struct, file)
-
-static const struct bpf_func_proto bpf_sock_from_file_proto = {
-	.func		= bpf_sock_from_file,
-	.gpl_only	= false,
-	.ret_type	= RET_PTR_TO_BTF_ID_OR_NULL,
-	.ret_btf_id	= &bpf_sock_from_file_btf_ids[0],
-	.arg1_type	= ARG_PTR_TO_BTF_ID,
-	.arg1_btf_id	= &bpf_sock_from_file_btf_ids[1],
-};
-
 const struct bpf_func_proto *
 bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 {
@@ -1384,8 +1366,6 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_per_cpu_ptr_proto;
 	case BPF_FUNC_bpf_this_cpu_ptr:
 		return &bpf_this_cpu_ptr_proto;
-	case BPF_FUNC_sock_from_file:
-		return &bpf_sock_from_file_proto;
 	default:
 		return NULL;
 	}
@@ -1778,6 +1758,8 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_sk_storage_get_tracing_proto;
 	case BPF_FUNC_sk_storage_delete:
 		return &bpf_sk_storage_delete_tracing_proto;
+	case BPF_FUNC_sock_from_file:
+		return &bpf_sock_from_file_proto;
 #endif
 	case BPF_FUNC_seq_printf:
 		return prog->expected_attach_type == BPF_TRACE_ITER ?
diff --git a/net/core/filter.c b/net/core/filter.c
index 77001a35768f..255aeee72402 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -10413,6 +10413,24 @@ const struct bpf_func_proto bpf_skc_to_udp6_sock_proto = {
 	.ret_btf_id		= &btf_sock_ids[BTF_SOCK_TYPE_UDP6],
 };
 
+BPF_CALL_1(bpf_sock_from_file, struct file *, file)
+{
+	return (unsigned long)sock_from_file(file);
+}
+
+BTF_ID_LIST(bpf_sock_from_file_btf_ids)
+BTF_ID(struct, socket)
+BTF_ID(struct, file)
+
+const struct bpf_func_proto bpf_sock_from_file_proto = {
+	.func		= bpf_sock_from_file,
+	.gpl_only	= false,
+	.ret_type	= RET_PTR_TO_BTF_ID_OR_NULL,
+	.ret_btf_id	= &bpf_sock_from_file_btf_ids[0],
+	.arg1_type	= ARG_PTR_TO_BTF_ID,
+	.arg1_btf_id	= &bpf_sock_from_file_btf_ids[1],
+};
+
 static const struct bpf_func_proto *
 bpf_sk_base_func_proto(enum bpf_func_id func_id)
 {
-- 
2.29.2.576.ga3fc446d84-goog