From patchwork Thu Dec 7 14:15:00 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hou Tao X-Patchwork-Id: 13483340 X-Patchwork-Delegate: bpf@iogearbox.net Received: from dggsgout11.his.huawei.com (unknown [45.249.212.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B78810D1 for ; Thu, 7 Dec 2023 06:14:00 -0800 (PST) Received: from mail.maildlp.com (unknown [172.19.93.142]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4SmGTr5ff2z4f3l1h for ; Thu, 7 Dec 2023 22:13:52 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.112]) by mail.maildlp.com (Postfix) with ESMTP id 867871A083D for ; Thu, 7 Dec 2023 22:13:57 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.124.27]) by APP1 (Coremail) with SMTP id cCh0CgA3iA4h03FlXhr9Cw--.42307S4; Thu, 07 Dec 2023 22:13:55 +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 v2] selftests/bpf: Test the release of map btf Date: Thu, 7 Dec 2023 22:15:00 +0800 Message-Id: <20231207141500.917136-1-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: cCh0CgA3iA4h03FlXhr9Cw--.42307S4 X-Coremail-Antispam: 1UD129KBjvJXoW3Ar4rXr4fAF1rXFWrKw4kWFg_yoW3KF4fpa yrKr1Ykr1vgwsrWrW8Ja1YkFyrtw48Z34UtrnYg34YvrWUZry3Xr4IgFW7tFnIkrZ7KF4Y v3ZIqF18C397AFJanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkFb4IE77IF4wAFF20E14v26r4j6ryUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxV AFwI0_GcCE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2 j2WlYx0E2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7x kEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCF04k20xvY 0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I 0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAI cVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcV CF04k26cxKx2IYs7xG6rWUJVWrZr1UMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2 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. And the use-after-free problem can been easily reproduced by using bpf_next tree and a KASAN-enabled kernel. 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. To delay the free of array map and make it be invoked after btf_free_rcu() is invoked, it stresses system_unbound_wq by closing multiple percpu array maps before it closes the array map. 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 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 Acked-by: Yonghong Song --- Change log: v2: * make map_btf/array_btf to reproduce the UAF problem reliably * update comment in do_test_map_in_map_btf() * check done in add_to_list_in_{array,inner_array}() v1: https://lore.kernel.org/bpf/81c277e9-856c-7763-8e76-7b76aa39d1dc@huaweicloud.com .../selftests/bpf/prog_tests/map_btf.c | 98 +++++++++++++++++++ .../selftests/bpf/progs/map_in_map_btf.c | 73 ++++++++++++++ .../selftests/bpf/progs/normal_map_btf.c | 56 +++++++++++ 3 files changed, 227 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..2c4ef6037573 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/map_btf.c @@ -0,0 +1,98 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2023. Huawei Technologies Co., Ltd */ +#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 i, err, new_fd = -1; + int map_fd_arr[64]; + + 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"); + + /* Use percpu_array to slow bpf_map_free_deferred() down. + * The memory allocation may fail, so doesn't check the returned fd. + */ + for (i = 0; i < ARRAY_SIZE(map_fd_arr); i++) + map_fd_arr[i] = bpf_map_create(BPF_MAP_TYPE_PERCPU_ARRAY, NULL, 4, 4, 256, NULL); + + /* 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(4000); + /* Spawn multiple kworkers to delay the invocation of + * bpf_map_free_deferred() for array map. + */ + for (i = 0; i < ARRAY_SIZE(map_fd_arr); i++) { + if (map_fd_arr[i] < 0) + continue; + close(map_fd_arr[i]); + } + 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, inner 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..7a1336d7b16a --- /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 (done || (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..66cde82aa86d --- /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 (done || (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; +}