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Tue, 17 Dec 2019 01:47:33 -0800 (PST) From: Wenbo Zhang To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, yhs@fb.com, bgregg@netflix.com, andrii.nakryiko@gmail.com, netdev@vger.kernel.org Subject: [PATCH bpf-next v13 2/2] selftests/bpf: test for bpf_get_fd_path() from tracepoint Date: Tue, 17 Dec 2019 04:47:17 -0500 Message-Id: <56f0db8d7556bf84ccb3705b58d4e88ead04c894.1576575253.git.ethercflow@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: References: <0117d6e17ba8b3b1273e5a964f87a71c1b2d8741.1576381512.git.ethercflow@gmail.com> In-Reply-To: References: Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org trace fstat events by tracepoint syscalls/sys_enter_newfstat, and handle events only produced by test_file_fd_path, which call fstat on several different types of files to test bpf_fd_file_path's feature. v5->v6: addressed Gregg and Yonghong's feedback - rename to get_fd_path - change sys_enter_newfstat_args's fd type to long to fix issue on big-endian machines v4->v5: addressed Andrii's feedback - pass NULL for opts as bpf_object__open_file's PARAM2, as not really using any - modify patch subject to keep up with test code - as this test is single-threaded, so use getpid instead of SYS_gettid - remove unnecessary parens around check which after if (i < 3) - in kern use bpf_get_current_pid_tgid() >> 32 to fit getpid() in userspace part - with the patch adding helper as one patch series v3->v4: addressed Andrii's feedback - use a set of fd instead of fds array - use global variables instead of maps (in v3, I mistakenly thought that the bpf maps are global variables.) - remove uncessary global variable path_info_index - remove fd compare as the fstat's order is fixed v2->v3: addressed Andrii's feedback - use global data instead of perf_buffer to simplified code v1->v2: addressed Daniel's feedback - rename bpf_fd2path to bpf_get_file_path to be consistent with other helper's names Signed-off-by: Wenbo Zhang --- .../selftests/bpf/prog_tests/get_fd_path.c | 171 ++++++++++++++++++ .../selftests/bpf/progs/test_get_fd_path.c | 43 +++++ 2 files changed, 214 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/get_fd_path.c create mode 100644 tools/testing/selftests/bpf/progs/test_get_fd_path.c diff --git a/tools/testing/selftests/bpf/prog_tests/get_fd_path.c b/tools/testing/selftests/bpf/prog_tests/get_fd_path.c new file mode 100644 index 000000000000..5cf58028a8d2 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/get_fd_path.c @@ -0,0 +1,171 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include +#include +#include +#include + +#define MAX_PATH_LEN 128 +#define MAX_FDS 7 +#define MAX_EVENT_NUM 16 + +static struct fd_path_test_data { + pid_t pid; + __u32 cnt; + __u32 fds[MAX_EVENT_NUM]; + char paths[MAX_EVENT_NUM][MAX_PATH_LEN]; +} src, dst; + +static int set_pathname(int fd) +{ + char buf[MAX_PATH_LEN]; + + snprintf(buf, MAX_PATH_LEN, "/proc/%d/fd/%d", src.pid, fd); + src.fds[src.cnt] = fd; + return readlink(buf, src.paths[src.cnt++], MAX_PATH_LEN); +} + +static int trigger_fstat_events(pid_t pid) +{ + int pipefd[2] = { -1, -1 }; + int sockfd = -1, procfd = -1, devfd = -1; + int localfd = -1, indicatorfd = -1; + struct stat fileStat; + int ret = -1; + + /* unmountable pseudo-filesystems */ + if (CHECK_FAIL(pipe(pipefd) < 0)) + return ret; + /* unmountable pseudo-filesystems */ + sockfd = socket(AF_INET, SOCK_STREAM, 0); + if (CHECK_FAIL(sockfd < 0)) + goto out_close; + /* mountable pseudo-filesystems */ + procfd = open("/proc/self/comm", O_RDONLY); + if (CHECK_FAIL(procfd < 0)) + goto out_close; + devfd = open("/dev/urandom", O_RDONLY); + if (CHECK_FAIL(devfd < 0)) + goto out_close; + localfd = open("/tmp/fd2path_loadgen.txt", O_CREAT | O_RDONLY); + if (CHECK_FAIL(localfd < 0)) + goto out_close; + /* bpf_get_fd_path will return path with (deleted) */ + remove("/tmp/fd2path_loadgen.txt"); + indicatorfd = open("/tmp/", O_PATH); + if (CHECK_FAIL(indicatorfd < 0)) + goto out_close; + + src.pid = pid; + + ret = set_pathname(pipefd[0]); + if (CHECK_FAIL(ret < 0)) + goto out_close; + ret = set_pathname(pipefd[1]); + if (CHECK_FAIL(ret < 0)) + goto out_close; + ret = set_pathname(sockfd); + if (CHECK_FAIL(ret < 0)) + goto out_close; + ret = set_pathname(procfd); + if (CHECK_FAIL(ret < 0)) + goto out_close; + ret = set_pathname(devfd); + if (CHECK_FAIL(ret < 0)) + goto out_close; + ret = set_pathname(localfd); + if (CHECK_FAIL(ret < 0)) + goto out_close; + ret = set_pathname(indicatorfd); + if (CHECK_FAIL(ret < 0)) + goto out_close; + + fstat(pipefd[0], &fileStat); + fstat(pipefd[1], &fileStat); + fstat(sockfd, &fileStat); + fstat(procfd, &fileStat); + fstat(devfd, &fileStat); + fstat(localfd, &fileStat); + fstat(indicatorfd, &fileStat); + +out_close: + close(indicatorfd); + close(localfd); + close(devfd); + close(procfd); + close(sockfd); + close(pipefd[1]); + close(pipefd[0]); + + return ret; +} + +void test_get_fd_path(void) +{ + const char *prog_name = "tracepoint/syscalls/sys_enter_newfstat"; + const char *obj_file = "test_get_fd_path.o"; + int err, results_map_fd, duration = 0; + struct bpf_program *tp_prog = NULL; + struct bpf_link *tp_link = NULL; + struct bpf_object *obj = NULL; + const int zero = 0; + + obj = bpf_object__open_file(obj_file, NULL); + if (CHECK(IS_ERR(obj), "obj_open_file", "err %ld\n", PTR_ERR(obj))) + return; + + tp_prog = bpf_object__find_program_by_title(obj, prog_name); + if (CHECK(!tp_prog, "find_tp", + "prog '%s' not found\n", prog_name)) + goto cleanup; + + err = bpf_object__load(obj); + if (CHECK(err, "obj_load", "err %d\n", err)) + goto cleanup; + + results_map_fd = bpf_find_map(__func__, obj, "test_get.bss"); + if (CHECK(results_map_fd < 0, "find_bss_map", + "err %d\n", results_map_fd)) + goto cleanup; + + tp_link = bpf_program__attach_tracepoint(tp_prog, "syscalls", + "sys_enter_newfstat"); + if (CHECK(IS_ERR(tp_link), "attach_tp", + "err %ld\n", PTR_ERR(tp_link))) { + tp_link = NULL; + goto cleanup; + } + + dst.pid = getpid(); + err = bpf_map_update_elem(results_map_fd, &zero, &dst, 0); + if (CHECK(err, "update_elem", + "failed to set pid filter: %d\n", err)) + goto cleanup; + + err = trigger_fstat_events(dst.pid); + if (CHECK_FAIL(err < 0)) + goto cleanup; + + err = bpf_map_lookup_elem(results_map_fd, &zero, &dst); + if (CHECK(err, "get_results", + "failed to get results: %d\n", err)) + goto cleanup; + + for (int i = 0; i < MAX_FDS; i++) { + if (i < 3) + CHECK((dst.paths[i][0] != '0'), "get_fd_path", + "failed to filter fs [%d]: %u(%s) vs %u(%s)\n", + i, src.fds[i], src.paths[i], dst.fds[i], + dst.paths[i]); + else + CHECK(strncmp(src.paths[i], dst.paths[i], MAX_PATH_LEN), + "get_fd_path", + "failed to get path[%d]: %u(%s) vs %u(%s)\n", + i, src.fds[i], src.paths[i], dst.fds[i], + dst.paths[i]); + } + +cleanup: + bpf_link__destroy(tp_link); + bpf_object__close(obj); +} diff --git a/tools/testing/selftests/bpf/progs/test_get_fd_path.c b/tools/testing/selftests/bpf/progs/test_get_fd_path.c new file mode 100644 index 000000000000..8bb58f87755e --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_get_fd_path.c @@ -0,0 +1,43 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include +#include +#include "bpf_helpers.h" +#include "bpf_tracing.h" + +#define MAX_PATH_LEN 128 +#define MAX_EVENT_NUM 16 + +static struct fd_path_test_data { + pid_t pid; + __u32 cnt; + __u32 fds[MAX_EVENT_NUM]; + char paths[MAX_EVENT_NUM][MAX_PATH_LEN]; +} data; + +struct sys_enter_newfstat_args { + unsigned long long pad1; + unsigned long long pad2; + unsigned long fd; +}; + +SEC("tracepoint/syscalls/sys_enter_newfstat") +int bpf_prog(struct sys_enter_newfstat_args *args) +{ + pid_t pid = bpf_get_current_pid_tgid() >> 32; + + if (pid != data.pid) + return 0; + if (data.cnt >= MAX_EVENT_NUM) + return 0; + + data.fds[data.cnt] = args->fd; + bpf_get_fd_path(data.paths[data.cnt], MAX_PATH_LEN, args->fd); + data.cnt++; + + return 0; +} + +char _license[] SEC("license") = "GPL"; -- 2.17.1