{"id":2225116,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2225116/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260420105816.72168-7-mahe.tardy@gmail.com/","project":{"id":26,"url":"http://patchwork.ozlabs.org/api/1.1/projects/26/?format=json","name":"Netfilter Development","link_name":"netfilter-devel","list_id":"netfilter-devel.vger.kernel.org","list_email":"netfilter-devel@vger.kernel.org","web_url":null,"scm_url":null,"webscm_url":null},"msgid":"<20260420105816.72168-7-mahe.tardy@gmail.com>","date":"2026-04-20T10:58:16","name":"[bpf-next,v4,6/6] selftests/bpf: add icmp_send_unreach_recursion test","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"b1c97ebb76d3c8ef1f15366d6516e0e071860806","submitter":{"id":91349,"url":"http://patchwork.ozlabs.org/api/1.1/people/91349/?format=json","name":"Mahe Tardy","email":"mahe.tardy@gmail.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260420105816.72168-7-mahe.tardy@gmail.com/mbox/","series":[{"id":500597,"url":"http://patchwork.ozlabs.org/api/1.1/series/500597/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/list/?series=500597","date":"2026-04-20T10:58:10","name":"bpf: add icmp_send_unreach kfunc","version":4,"mbox":"http://patchwork.ozlabs.org/series/500597/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2225116/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2225116/checks/","tags":{},"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","netfilter-devel@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 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","To":"mahe.tardy@gmail.com","Cc":"alexei.starovoitov@gmail.com,\n\tandrii@kernel.org,\n\tast@kernel.org,\n\tbpf@vger.kernel.org,\n\tcoreteam@netfilter.org,\n\tdaniel@iogearbox.net,\n\tfw@strlen.de,\n\tjohn.fastabend@gmail.com,\n\tlkp@intel.com,\n\tmartin.lau@linux.dev,\n\tnetdev@vger.kernel.org,\n\tnetfilter-devel@vger.kernel.org,\n\toe-kbuild-all@lists.linux.dev,\n\tpablo@netfilter.org","Subject":"[PATCH bpf-next v4 6/6] selftests/bpf: add\n icmp_send_unreach_recursion test","Date":"Mon, 20 Apr 2026 10:58:16 +0000","Message-Id":"<20260420105816.72168-7-mahe.tardy@gmail.com>","X-Mailer":"git-send-email 2.34.1","In-Reply-To":"<20260420105816.72168-1-mahe.tardy@gmail.com>","References":"\n <20260420105816.72168-1-mahe.tardy@gmail.com>","Precedence":"bulk","X-Mailing-List":"netfilter-devel@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit"},"content":"This test is similar to icmp_send_unreach_kfunc but checks that, in case\nof recursion, meaning that the BPF program calling the kfunc was\nre-triggered by the icmp_send done by the kfunc, the kfunc will stop\nearly and return -EBUSY.\n\nSigned-off-by: Mahe Tardy \n---\n .../bpf/prog_tests/icmp_send_unreach_kfunc.c | 43 +++++++++++++++++++\n .../selftests/bpf/progs/icmp_send_unreach.c | 30 +++++++++++++\n 2 files changed, 73 insertions(+)\n\n--\n2.34.1","diff":"diff --git a/tools/testing/selftests/bpf/prog_tests/icmp_send_unreach_kfunc.c b/tools/testing/selftests/bpf/prog_tests/icmp_send_unreach_kfunc.c\nindex 047bfd4d80f7..a4f4324b2b99 100644\n--- a/tools/testing/selftests/bpf/prog_tests/icmp_send_unreach_kfunc.c\n+++ b/tools/testing/selftests/bpf/prog_tests/icmp_send_unreach_kfunc.c\n@@ -1,6 +1,7 @@\n // SPDX-License-Identifier: GPL-2.0\n #include \n #include \n+#include \n #include \n #include \"icmp_send_unreach.skel.h\"\n\n@@ -10,6 +11,7 @@\n #define ICMP_DEST_UNREACH 3\n #define ICMPV6_DEST_UNREACH 1\n\n+#define ICMP_HOST_UNREACH 1\n #define ICMP_FRAG_NEEDED 4\n #define NR_ICMP_UNREACH 15\n #define NR_ICMPV6_UNREACH 6\n@@ -157,3 +159,44 @@ void test_icmp_send_unreach_kfunc(void)\n \ticmp_send_unreach__destroy(skel);\n \tclose(cgroup_fd);\n }\n+\n+void test_icmp_send_unreach_recursion(void)\n+{\n+\tstruct icmp_send_unreach *skel;\n+\tint cgroup_fd = -1;\n+\tint *code;\n+\n+\tskel = icmp_send_unreach__open_and_load();\n+\tif (!ASSERT_OK_PTR(skel, \"skel_open\"))\n+\t\tgoto cleanup;\n+\n+\tif (setup_cgroup_environment()) {\n+\t\tfprintf(stderr, \"Failed to setup cgroup environment\\n\");\n+\t\tgoto cleanup;\n+\t}\n+\n+\tcgroup_fd = get_root_cgroup();\n+\tif (!ASSERT_GE(cgroup_fd, 0, \"get_root_cgroup\"))\n+\t\tgoto cleanup;\n+\n+\tskel->links.recursion =\n+\t\tbpf_program__attach_cgroup(skel->progs.recursion, cgroup_fd);\n+\tif (!ASSERT_OK_PTR(skel->links.recursion, \"prog_attach_cgroup\"))\n+\t\tgoto cleanup;\n+\n+\tcode = &skel->bss->unreach_code;\n+\t*code = ICMP_HOST_UNREACH;\n+\n+\ttrigger_prog_read_icmp_errqueue(code, AF_INET, \"127.0.0.1\");\n+\n+\t/* Because there's recursion involved, the first call will return at\n+\t * index 1 since it will return the second, and the second call will\n+\t * return at index 0 since it will return the first.\n+\t */\n+\tASSERT_EQ(skel->data->rec_kfunc_rets[1], 0, \"kfunc_rets[1]\");\n+\tASSERT_EQ(skel->data->rec_kfunc_rets[0], -EBUSY, \"kfunc_rets[0]\");\n+\n+cleanup:\n+\ticmp_send_unreach__destroy(skel);\n+\tclose(cgroup_fd);\n+}\ndiff --git a/tools/testing/selftests/bpf/progs/icmp_send_unreach.c b/tools/testing/selftests/bpf/progs/icmp_send_unreach.c\nindex 112b9cbfab6f..9aca7c0b12e1 100644\n--- a/tools/testing/selftests/bpf/progs/icmp_send_unreach.c\n+++ b/tools/testing/selftests/bpf/progs/icmp_send_unreach.c\n@@ -15,6 +15,9 @@\n int unreach_code = 0;\n int kfunc_ret = -1;\n\n+uint rec_count = 0;\n+int rec_kfunc_rets[] = { -1, -1 };\n+\n SEC(\"cgroup_skb/egress\")\n int egress(struct __sk_buff *skb)\n {\n@@ -67,4 +70,31 @@ int egress(struct __sk_buff *skb)\n \treturn SK_DROP;\n }\n\n+SEC(\"cgroup_skb/egress\")\n+int recursion(struct __sk_buff *skb)\n+{\n+\tvoid *data = (void *)(long)skb->data;\n+\tvoid *data_end = (void *)(long)skb->data_end;\n+\tstruct iphdr *iph;\n+\n+\tiph = data;\n+\tif ((void *)(iph + 1) > data_end || iph->version != 4)\n+\t\treturn SK_PASS;\n+\n+\t/* This call will provoke a recursion: the ICMP package generated by the\n+\t * kfunc will re-trigger this program since we are in the root cgroup in\n+\t * which the kernel ICMP socket belongs. However when re-entering the\n+\t * kfunc, it should return EBUSY.\n+\t */\n+\trec_kfunc_rets[rec_count & 1] =\n+\t\tbpf_icmp_send_unreach(skb, unreach_code);\n+\t__sync_fetch_and_add(&rec_count, 1);\n+\n+\t/* Let the first ICMP error message pass */\n+\tif (iph->protocol == IPPROTO_ICMP)\n+\t\treturn SK_PASS;\n+\n+\treturn SK_DROP;\n+}\n+\n char LICENSE[] SEC(\"license\") = \"Dual BSD/GPL\";\n","prefixes":["bpf-next","v4","6/6"]}