From patchwork Wed Dec 6 11:06:25 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hou Tao X-Patchwork-Id: 13481552 X-Patchwork-Delegate: bpf@iogearbox.net Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 288B21736 for ; Wed, 6 Dec 2023 03:05:24 -0800 (PST) Received: from mail.maildlp.com (unknown [172.19.93.142]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4SlZLm3g55z4f3l8h for ; Wed, 6 Dec 2023 19:05:20 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.112]) by mail.maildlp.com (Postfix) with ESMTP id 9028A1A08E9 for ; Wed, 6 Dec 2023 19:05:21 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.124.27]) by APP1 (Coremail) with SMTP id cCh0CgDX2xFuVXBl8riTCw--.41560S4; Wed, 06 Dec 2023 19:05:20 +0800 (CST) From: Hou Tao To: bpf@vger.kernel.org Cc: Martin KaFai Lau , Alexei Starovoitov , Andrii Nakryiko , Song Liu , Hao Luo , Yonghong Song , Daniel Borkmann , KP Singh , Stanislav Fomichev , Jiri Olsa , John Fastabend , houtao1@huawei.com Subject: [PATCH bpf-next] selftests/bpf: Test the release of map btf Date: Wed, 6 Dec 2023 19:06:25 +0800 Message-Id: <20231206110625.3188975-1-houtao@huaweicloud.com> X-Mailer: git-send-email 2.29.2 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: cCh0CgDX2xFuVXBl8riTCw--.41560S4 X-Coremail-Antispam: 1UD129KBjvJXoW3Ar4rXr4xGFyxZw47Gw15Arb_yoW3Zw17pa yrKr1Ykr4vqwsrWrW8Ga1YkF4ftw48Zw1UtrnYg34YvrWjvr9xXr4IgFWUtF1akrZ2gr4Y v3ZIqFWxC397Z3DanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkFb4IE77IF4wAFF20E14v26r4j6ryUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Cr0_Gr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I 0E14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40E x7xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x 0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1l42xK82IY c2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s 026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF 0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMIIF0x vE42xK8VAvwI8IcIk0rVWrZr1j6s0DMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2 jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x07UWE__UUUUU= X-CM-SenderInfo: xkrx3t3r6k3tpzhluzxrxghudrp/ X-Patchwork-Delegate: bpf@iogearbox.net From: Hou Tao When there is bpf_list_head or bpf_rb_root field in map value, the free of map btf and the free of map value may run concurrently and there may be use-after-free problem, so add two test cases to demonstrate it. The first test case tests the racing between the free of map btf and the free of array map. It constructs the racing by releasing the array map in the end after other ref-counter of map btf has been released. But it is still hard to reproduce the UAF problem, and I managed to reproduce it by queuing multiple kworkers to stress system_unbound_wq concurrently. The second case tests the racing between the free of map btf and the free of inner map. Beside using the similar method as the first one does, it uses bpf_map_delete_elem() to delete the inner map and to defer the release of inner map after one RCU grace period. The UAF problem can been easily reproduced by using bpf_next tree and a KASAN-enabled kernel. The reason for using two skeletons is to prevent the release of outer map and inner map in map_in_map_btf.c interfering the release of bpf map in normal_map_btf.c. Signed-off-by: Hou Tao --- Hi, I was also working on the UAF problem caused by the racing between the free map btf and the free map value. However considering Yonghong posted the patch first [1], I decided to post the selftest for the problem. The reliable reproduce of the problem depends on the "Fix the release of inner map" patch-set in bpf-next. [1]: https://lore.kernel.org/bpf/20231205224812.813224-1-yonghong.song@linux.dev/ .../selftests/bpf/prog_tests/map_btf.c | 88 +++++++++++++++++++ .../selftests/bpf/progs/map_in_map_btf.c | 73 +++++++++++++++ .../selftests/bpf/progs/normal_map_btf.c | 56 ++++++++++++ 3 files changed, 217 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/map_btf.c create mode 100644 tools/testing/selftests/bpf/progs/map_in_map_btf.c create mode 100644 tools/testing/selftests/bpf/progs/normal_map_btf.c diff --git a/tools/testing/selftests/bpf/prog_tests/map_btf.c b/tools/testing/selftests/bpf/prog_tests/map_btf.c new file mode 100644 index 000000000000..5304eee0e8f8 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/map_btf.c @@ -0,0 +1,88 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2023. Huawei Technologies Co., Ltd */ +#define _GNU_SOURCE +#include +#include +#include +#include +#include + +#include "normal_map_btf.skel.h" +#include "map_in_map_btf.skel.h" + +static void do_test_normal_map_btf(void) +{ + struct normal_map_btf *skel; + int err, new_fd = -1; + + skel = normal_map_btf__open_and_load(); + if (!ASSERT_OK_PTR(skel, "open_load")) + return; + + err = normal_map_btf__attach(skel); + if (!ASSERT_OK(err, "attach")) + goto out; + + skel->bss->pid = getpid(); + usleep(1); + ASSERT_TRUE(skel->bss->done, "done"); + + /* Close array fd later */ + new_fd = dup(bpf_map__fd(skel->maps.array)); +out: + normal_map_btf__destroy(skel); + if (new_fd < 0) + return; + /* Use kern_sync_rcu() to wait for the start of the free of the bpf + * program and use an assumed delay to wait for the release of the map + * btf which is held by other maps (e.g, bss). After that, array map + * holds the last reference of map btf. + */ + kern_sync_rcu(); + usleep(2000); + close(new_fd); +} + +static void do_test_map_in_map_btf(void) +{ + int err, zero = 0, new_fd = -1; + struct map_in_map_btf *skel; + + skel = map_in_map_btf__open_and_load(); + if (!ASSERT_OK_PTR(skel, "open_load")) + return; + + err = map_in_map_btf__attach(skel); + if (!ASSERT_OK(err, "attach")) + goto out; + + skel->bss->pid = getpid(); + usleep(1); + ASSERT_TRUE(skel->bss->done, "done"); + + /* Close inner_array fd later */ + new_fd = dup(bpf_map__fd(skel->maps.inner_array)); + /* Defer the free of inner_array */ + err = bpf_map__delete_elem(skel->maps.outer_array, &zero, sizeof(zero), 0); + ASSERT_OK(err, "delete inner map"); +out: + map_in_map_btf__destroy(skel); + if (new_fd < 0) + return; + /* Use kern_sync_rcu() to wait for the start of the free of the bpf + * program and use an assumed delay to wait for the free of the outer + * map and the release of map btf. After that, array map holds the last + * reference of map btf. + */ + kern_sync_rcu(); + usleep(10000); + close(new_fd); +} + +void test_map_btf(void) +{ + if (test__start_subtest("array_btf")) + do_test_normal_map_btf(); + if (test__start_subtest("inner_array_btf")) + do_test_map_in_map_btf(); +} diff --git a/tools/testing/selftests/bpf/progs/map_in_map_btf.c b/tools/testing/selftests/bpf/progs/map_in_map_btf.c new file mode 100644 index 000000000000..6a000dd789d3 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/map_in_map_btf.c @@ -0,0 +1,73 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2023. Huawei Technologies Co., Ltd */ +#include +#include +#include + +#include "bpf_misc.h" +#include "bpf_experimental.h" + +struct node_data { + __u64 data; + struct bpf_list_node node; +}; + +struct map_value { + struct bpf_list_head head __contains(node_data, node); + struct bpf_spin_lock lock; +}; + +struct inner_array_type { + __uint(type, BPF_MAP_TYPE_ARRAY); + __type(key, int); + __type(value, struct map_value); + __uint(max_entries, 1); +} inner_array SEC(".maps"); + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS); + __uint(key_size, 4); + __uint(value_size, 4); + __uint(max_entries, 1); + __array(values, struct inner_array_type); +} outer_array SEC(".maps") = { + .values = { + [0] = &inner_array, + }, +}; + +char _license[] SEC("license") = "GPL"; + +int pid = 0; +bool done = false; + +SEC("fentry/" SYS_PREFIX "sys_nanosleep") +int add_to_list_in_inner_array(void *ctx) +{ + struct map_value *value; + struct node_data *new; + struct bpf_map *map; + int zero = 0; + + if ((u32)bpf_get_current_pid_tgid() != pid) + return 0; + + map = bpf_map_lookup_elem(&outer_array, &zero); + if (!map) + return 0; + + value = bpf_map_lookup_elem(map, &zero); + if (!value) + return 0; + + new = bpf_obj_new(typeof(*new)); + if (!new) + return 0; + + bpf_spin_lock(&value->lock); + bpf_list_push_back(&value->head, &new->node); + bpf_spin_unlock(&value->lock); + done = true; + + return 0; +} diff --git a/tools/testing/selftests/bpf/progs/normal_map_btf.c b/tools/testing/selftests/bpf/progs/normal_map_btf.c new file mode 100644 index 000000000000..c8a19e30f8a9 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/normal_map_btf.c @@ -0,0 +1,56 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2023. Huawei Technologies Co., Ltd */ +#include +#include +#include + +#include "bpf_misc.h" +#include "bpf_experimental.h" + +struct node_data { + __u64 data; + struct bpf_list_node node; +}; + +struct map_value { + struct bpf_list_head head __contains(node_data, node); + struct bpf_spin_lock lock; +}; + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __type(key, int); + __type(value, struct map_value); + __uint(max_entries, 1); +} array SEC(".maps"); + +char _license[] SEC("license") = "GPL"; + +int pid = 0; +bool done = false; + +SEC("fentry/" SYS_PREFIX "sys_nanosleep") +int add_to_list_in_array(void *ctx) +{ + struct map_value *value; + struct node_data *new; + int zero = 0; + + if ((u32)bpf_get_current_pid_tgid() != pid) + return 0; + + value = bpf_map_lookup_elem(&array, &zero); + if (!value) + return 0; + + new = bpf_obj_new(typeof(*new)); + if (!new) + return 0; + + bpf_spin_lock(&value->lock); + bpf_list_push_back(&value->head, &new->node); + bpf_spin_unlock(&value->lock); + done = true; + + return 0; +}