From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f53.google.com (mail-wm1-f53.google.com [209.85.128.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 872A839B49D for ; Mon, 20 Apr 2026 10:58:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776682717; cv=none; b=lifDyc9DM9R3zlq04vDdqFrz7zfLGFni0JW+ButUfEfJzLVJGZdH5weJvIG9IO7nbDfj+vHWAk2b66MosDy3ccRJI1j3nLjZEq5sllld1eKOoVQMiBTj4mCeDrS4Q5KtlFXqY+YEJQZwJ1F7RX4BQdjZnpNSboZNNIkFq8lT4AE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776682717; c=relaxed/simple; bh=oDrClojuOmoFQWD8kdi7OYjx+xfYmqROcI/D6DoFoI0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=mT/hchKQbqafkLYmLEJ4kIm7Glcr+XEiT+kIhretwdqE717JjOAEkAlAKIBnRwtcFw6ERnqXqWL59QakKSyoVtndTqggv5eJzlljc1Gqw/3MVos+ZY6vaLB9eHQCoDe5JcWrF1iTI3xhbIZQgcRgT7ODfblE8ZBNaTNvESg+bGc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=AMGOhbbb; arc=none smtp.client-ip=209.85.128.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="AMGOhbbb" Received: by mail-wm1-f53.google.com with SMTP id 5b1f17b1804b1-488b0e1b870so44705455e9.2 for ; Mon, 20 Apr 2026 03:58:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1776682714; x=1777287514; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=xJxI2HSQPAxVmr77kvDE3un+rWp4GINOCWCL47TtY40=; b=AMGOhbbbPawejQreqA6zT8b5PPyCdN1n01uciSzHdG4MjndS+/mvJUJ5OeaasEiINm MyLOAXF9Ja72hTlG1bQ8QfIsVVC6jyrh/KtQyQShuSpVHN71HyXxui+pVrPeCt8niRI2 86JnBAaCpWcXdXr4tskcyD//sHQIrD9FU0bra+imVlpcNFYBE/j/mAxzURltT6/8Mu3p gNsb642EcDthOSUEwDuu86HSlrOER5p53j+0YePNNNDm/i9dWF4nZR0d5mLC1a6GeKrW eTfDLar7l59+McnZkOy2uQJVCsuFfS4e1x+ln1ubCKKTPpnF6eOCBRJpYBlBhLm2qqbP ivkA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776682714; x=1777287514; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=xJxI2HSQPAxVmr77kvDE3un+rWp4GINOCWCL47TtY40=; b=A19Jyv4aeca18VbrCKhJCG9te6FrxzPgezp30JhM0lQlbNTAGkItpOTKLNmVli+lkL 4FxN1YaQg2jFKBhsVNAX3N+ZDIHoGo6h4Y6oAVQTkuvFrEgJYtEbVMsr7KgekacRGawq 8I+CuDoL+nbdNdvPF6jHOcpxQpYkcxi1va23yJ6jeXG+YpRUsAB/9R8+KyEF5D4swpcH tqb0AoizlqEq9mF/MICYVL6bPJCZOzGQtFnTE2HKixBOmopRXRUj0u3H+LDE4I8e843o kZzN3GfRWcX9VK8HwXMpyz722tJrPwVjqo4eUjkLTj8Ycg79SkZtEw9UzHhTqGVseFNy 9AgQ== X-Forwarded-Encrypted: i=1; AFNElJ/B3NIjlpF08a9/fLlP4xWK+clBTJsqobufF8dtd+fO2GTf9DbAlVsfMqdbSNrOyMx206mpuyY=@vger.kernel.org X-Gm-Message-State: AOJu0YyFv9jIOYuWhUSlKaZMxebrk3JzxNcQFu/W/aW/8dYgvsNWRKw2 4B93mIkrwbZyILwkdH+qLjenQJpgLXDhhyUOJY1SpxeNK4DV2NlI3gKK X-Gm-Gg: AeBDieup7nvF0M2Umljhk/EHZnQ645VCm9/LqUnB4ojf3YERGnvqGtOto1YSvK9VVAd Zedszre+lR+mU9emqe4UEDzPTCeLXgULhfBbA5l8XoHT8lhB8Y4GKPyIz+tvOH8vnY2l523vubH jsMNGIHltDC5oV8sC+ma/pJcSxG1M7cUBd8To4sa00SmzwDNFOUiGrfq6VbZ217agofF6GGRqFr 7NyMHgPogNYkVXTS2ySzG5N8rGqu0F15IwAVzhS5hZrzZlzsjrMiRwfwicZhWnV/MTFI/KLQqeX Ssc0Gxp1mwa/j/5BKnVrig7BiYemt6Dazrd2afCiA21ooQfwPeFSHysT8+w6RJiNfpbjrKZK4hx uAZct7FoHmXh9gU/lX/kwb5c7hk+ZvqLSOslFHxyiiycEtTcH5Zvsz1sk60Hc2mHM0NUs2vh2sW irSfUnP/rU8IesB+lUdXnYy6exm00LXeS6AOFKSw== X-Received: by 2002:a05:600c:1da1:b0:488:f453:b976 with SMTP id 5b1f17b1804b1-488fb7844c5mr207471835e9.27.1776682713605; Mon, 20 Apr 2026 03:58:33 -0700 (PDT) Received: from mtardy-friendly-lvh-runner.local ([2600:1900:4010:1a8::]) by smtp.googlemail.com with ESMTPSA id 5b1f17b1804b1-488fc1cfbf2sm290929495e9.15.2026.04.20.03.58.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Apr 2026 03:58:33 -0700 (PDT) From: Mahe Tardy To: mahe.tardy@gmail.com Cc: alexei.starovoitov@gmail.com, andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org, coreteam@netfilter.org, daniel@iogearbox.net, fw@strlen.de, john.fastabend@gmail.com, lkp@intel.com, martin.lau@linux.dev, netdev@vger.kernel.org, netfilter-devel@vger.kernel.org, oe-kbuild-all@lists.linux.dev, pablo@netfilter.org Subject: [PATCH bpf-next v4 6/6] selftests/bpf: add 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: <20260420105816.72168-1-mahe.tardy@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This test is similar to icmp_send_unreach_kfunc but checks that, in case of recursion, meaning that the BPF program calling the kfunc was re-triggered by the icmp_send done by the kfunc, the kfunc will stop early and return -EBUSY. Signed-off-by: Mahe Tardy --- .../bpf/prog_tests/icmp_send_unreach_kfunc.c | 43 +++++++++++++++++++ .../selftests/bpf/progs/icmp_send_unreach.c | 30 +++++++++++++ 2 files changed, 73 insertions(+) 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 index 047bfd4d80f7..a4f4324b2b99 100644 --- a/tools/testing/selftests/bpf/prog_tests/icmp_send_unreach_kfunc.c +++ b/tools/testing/selftests/bpf/prog_tests/icmp_send_unreach_kfunc.c @@ -1,6 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 #include #include +#include #include #include "icmp_send_unreach.skel.h" @@ -10,6 +11,7 @@ #define ICMP_DEST_UNREACH 3 #define ICMPV6_DEST_UNREACH 1 +#define ICMP_HOST_UNREACH 1 #define ICMP_FRAG_NEEDED 4 #define NR_ICMP_UNREACH 15 #define NR_ICMPV6_UNREACH 6 @@ -157,3 +159,44 @@ void test_icmp_send_unreach_kfunc(void) icmp_send_unreach__destroy(skel); close(cgroup_fd); } + +void test_icmp_send_unreach_recursion(void) +{ + struct icmp_send_unreach *skel; + int cgroup_fd = -1; + int *code; + + skel = icmp_send_unreach__open_and_load(); + if (!ASSERT_OK_PTR(skel, "skel_open")) + goto cleanup; + + if (setup_cgroup_environment()) { + fprintf(stderr, "Failed to setup cgroup environment\n"); + goto cleanup; + } + + cgroup_fd = get_root_cgroup(); + if (!ASSERT_GE(cgroup_fd, 0, "get_root_cgroup")) + goto cleanup; + + skel->links.recursion = + bpf_program__attach_cgroup(skel->progs.recursion, cgroup_fd); + if (!ASSERT_OK_PTR(skel->links.recursion, "prog_attach_cgroup")) + goto cleanup; + + code = &skel->bss->unreach_code; + *code = ICMP_HOST_UNREACH; + + trigger_prog_read_icmp_errqueue(code, AF_INET, "127.0.0.1"); + + /* Because there's recursion involved, the first call will return at + * index 1 since it will return the second, and the second call will + * return at index 0 since it will return the first. + */ + ASSERT_EQ(skel->data->rec_kfunc_rets[1], 0, "kfunc_rets[1]"); + ASSERT_EQ(skel->data->rec_kfunc_rets[0], -EBUSY, "kfunc_rets[0]"); + +cleanup: + icmp_send_unreach__destroy(skel); + close(cgroup_fd); +} diff --git a/tools/testing/selftests/bpf/progs/icmp_send_unreach.c b/tools/testing/selftests/bpf/progs/icmp_send_unreach.c index 112b9cbfab6f..9aca7c0b12e1 100644 --- a/tools/testing/selftests/bpf/progs/icmp_send_unreach.c +++ b/tools/testing/selftests/bpf/progs/icmp_send_unreach.c @@ -15,6 +15,9 @@ int unreach_code = 0; int kfunc_ret = -1; +uint rec_count = 0; +int rec_kfunc_rets[] = { -1, -1 }; + SEC("cgroup_skb/egress") int egress(struct __sk_buff *skb) { @@ -67,4 +70,31 @@ int egress(struct __sk_buff *skb) return SK_DROP; } +SEC("cgroup_skb/egress") +int recursion(struct __sk_buff *skb) +{ + void *data = (void *)(long)skb->data; + void *data_end = (void *)(long)skb->data_end; + struct iphdr *iph; + + iph = data; + if ((void *)(iph + 1) > data_end || iph->version != 4) + return SK_PASS; + + /* This call will provoke a recursion: the ICMP package generated by the + * kfunc will re-trigger this program since we are in the root cgroup in + * which the kernel ICMP socket belongs. However when re-entering the + * kfunc, it should return EBUSY. + */ + rec_kfunc_rets[rec_count & 1] = + bpf_icmp_send_unreach(skb, unreach_code); + __sync_fetch_and_add(&rec_count, 1); + + /* Let the first ICMP error message pass */ + if (iph->protocol == IPPROTO_ICMP) + return SK_PASS; + + return SK_DROP; +} + char LICENSE[] SEC("license") = "Dual BSD/GPL"; -- 2.34.1