[PATCH bpf v1 1/2] bpf: fix link info netfilter flags to populate defrag flag

[PATCH bpf v1 1/2] bpf: fix link info netfilter flags to populate defrag flag

[Tyrone Wu]

This patch correctly populates the `bpf_link_info.netfilter.flags` field
when user passes the `BPF_F_NETFILTER_IP_DEFRAG` flag.

Fixes: 84601d6ee68a ("bpf: add bpf_link support for BPF_NETFILTER programs")
Signed-off-by: Tyrone Wu <wudevelops@gmail.com>
---
 net/netfilter/nf_bpf_link.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nf_bpf_link.c b/net/netfilter/nf_bpf_link.c
index 5257d5e7eb09..797fe8a9971e 100644
--- a/net/netfilter/nf_bpf_link.c
+++ b/net/netfilter/nf_bpf_link.c
@@ -150,11 +150,12 @@ static int bpf_nf_link_fill_link_info(const struct bpf_link *link,
 				      struct bpf_link_info *info)
 {
 	struct bpf_nf_link *nf_link = container_of(link, struct bpf_nf_link, link);
+	const struct nf_defrag_hook *hook = nf_link->defrag_hook;
 
 	info->netfilter.pf = nf_link->hook_ops.pf;
 	info->netfilter.hooknum = nf_link->hook_ops.hooknum;
 	info->netfilter.priority = nf_link->hook_ops.priority;
-	info->netfilter.flags = 0;
+	info->netfilter.flags = hook ? BPF_F_NETFILTER_IP_DEFRAG : 0;
 
 	return 0;
 }
-- 
2.43.0

[PATCH bpf v1 2/2] selftests/bpf: add asserts for netfilter link info

[Tyrone Wu]

Add assertions/tests to verify `bpf_link_info` fields for netfilter link
are correctly populated.

Signed-off-by: Tyrone Wu <wudevelops@gmail.com>
---
 .../bpf/prog_tests/netfilter_link_attach.c    | 40 ++++++++++++++++++-
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/netfilter_link_attach.c b/tools/testing/selftests/bpf/prog_tests/netfilter_link_attach.c
index 4297a2a4cb11..5bf98ab2e17f 100644
--- a/tools/testing/selftests/bpf/prog_tests/netfilter_link_attach.c
+++ b/tools/testing/selftests/bpf/prog_tests/netfilter_link_attach.c
@@ -26,10 +26,43 @@ static const struct nf_link_test nf_hook_link_tests[] = {
 
 	{ .pf = NFPROTO_INET, .priority = 1, .name = "invalid-inet-not-supported", },
 
-	{ .pf = NFPROTO_IPV4, .priority = -10000, .expect_success = true, .name = "attach ipv4", },
-	{ .pf = NFPROTO_IPV6, .priority =  10001, .expect_success = true, .name = "attach ipv6", },
+	{
+		.pf = NFPROTO_IPV4,
+		.hooknum = NF_INET_POST_ROUTING,
+		.priority = -10000,
+		.flags = 0,
+		.expect_success = true,
+		.name = "attach ipv4",
+	},
+	{
+		.pf = NFPROTO_IPV6,
+		.hooknum = NF_INET_FORWARD,
+		.priority =  10001,
+		.flags = BPF_F_NETFILTER_IP_DEFRAG,
+		.expect_success = true,
+		.name = "attach ipv6",
+	},
 };
 
+static void verify_netfilter_link_info(struct bpf_link *link, const struct nf_link_test nf_expected)
+{
+	struct bpf_link_info info;
+	__u32 len = sizeof(info);
+	int err, fd;
+
+	memset(&info, 0, len);
+
+	fd = bpf_link__fd(link);
+	err = bpf_link_get_info_by_fd(fd, &info, &len);
+	ASSERT_OK(err, "get_link_info");
+
+	ASSERT_EQ(info.type, BPF_LINK_TYPE_NETFILTER, "info link type");
+	ASSERT_EQ(info.netfilter.pf, nf_expected.pf, "info nf protocol family");
+	ASSERT_EQ(info.netfilter.hooknum, nf_expected.hooknum, "info nf hooknum");
+	ASSERT_EQ(info.netfilter.priority, nf_expected.priority, "info nf priority");
+	ASSERT_EQ(info.netfilter.flags, nf_expected.flags, "info nf flags");
+}
+
 void test_netfilter_link_attach(void)
 {
 	struct test_netfilter_link_attach *skel;
@@ -63,6 +96,7 @@ void test_netfilter_link_attach(void)
 
 			if (!ASSERT_OK_PTR(link, "program attach successful"))
 				continue;
+			verify_netfilter_link_info(link, nf_hook_link_tests[i]);
 
 			link2 = bpf_program__attach_netfilter(prog, &opts);
 			ASSERT_ERR_PTR(link2, "attach program with same pf/hook/priority");
@@ -73,6 +107,8 @@ void test_netfilter_link_attach(void)
 			link2 = bpf_program__attach_netfilter(prog, &opts);
 			if (!ASSERT_OK_PTR(link2, "program reattach successful"))
 				continue;
+			verify_netfilter_link_info(link2, nf_hook_link_tests[i]);
+
 			if (!ASSERT_OK(bpf_link__destroy(link2), "link destroy"))
 				break;
 		} else {
-- 
2.43.0

Re: [PATCH bpf v1 1/2] bpf: fix link info netfilter flags to populate defrag flag

[Florian Westphal]

Tyrone Wu <wudevelops@gmail.com> wrote:
> This patch correctly populates the `bpf_link_info.netfilter.flags` field
> when user passes the `BPF_F_NETFILTER_IP_DEFRAG` flag.

Indeed, thanks for fixing this.
Patch and testcase look good, but one nit:

> Fixes: 84601d6ee68a ("bpf: add bpf_link support for BPF_NETFILTER programs")

BPF_F_NETFILTER_IP_DEFRAG flag was added in
91721c2d02d3 ("netfilter: bpf: Support BPF_F_NETFILTER_IP_DEFRAG in netfilter link"), that was a bit later than the initial support.

Other than that,
Acked-by: Florian Westphal <fw@strlen.de>

Re: [PATCH bpf v1 1/2] bpf: fix link info netfilter flags to populate defrag flag

[Daniel Borkmann]

On 10/15/24 5:25 PM, Florian Westphal wrote:
> Tyrone Wu <wudevelops@gmail.com> wrote:
>> This patch correctly populates the `bpf_link_info.netfilter.flags` field
>> when user passes the `BPF_F_NETFILTER_IP_DEFRAG` flag.
> 
> Indeed, thanks for fixing this.
> Patch and testcase look good, but one nit:
> 
>> Fixes: 84601d6ee68a ("bpf: add bpf_link support for BPF_NETFILTER programs")
> 
> BPF_F_NETFILTER_IP_DEFRAG flag was added in
> 91721c2d02d3 ("netfilter: bpf: Support BPF_F_NETFILTER_IP_DEFRAG in netfilter link"), that was a bit later than the initial support.
> 
> Other than that,
> Acked-by: Florian Westphal <fw@strlen.de>

Thanks Florian & Tyrone, fixed up Fixes tag while applying.

Re: [PATCH bpf v1 1/2] bpf: fix link info netfilter flags to populate defrag flag

[patchwork-bot+netdevbpf]

Hello:

This series was applied to bpf/bpf.git (master)
by Daniel Borkmann <daniel@iogearbox.net>:

On Fri, 11 Oct 2024 19:32:51 +0000 you wrote:
> This patch correctly populates the `bpf_link_info.netfilter.flags` field
> when user passes the `BPF_F_NETFILTER_IP_DEFRAG` flag.
> 
> Fixes: 84601d6ee68a ("bpf: add bpf_link support for BPF_NETFILTER programs")
> Signed-off-by: Tyrone Wu <wudevelops@gmail.com>
> ---
>  net/netfilter/nf_bpf_link.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)

Here is the summary with links:
  - [bpf,v1,1/2] bpf: fix link info netfilter flags to populate defrag flag
    https://git.kernel.org/bpf/bpf/c/92f3715e1eba
  - [bpf,v1,2/2] selftests/bpf: add asserts for netfilter link info
    https://git.kernel.org/bpf/bpf/c/2aa587fd6659

You are awesome, thank you!
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