Re: [PATCH 3/3] selftests: add readfile(2) selftests

Heinrich Schuchardt
2020-07-05T01:42:13Z

On 7/4/20 4:02 PM, Greg Kroah-Hartman wrote:
> Test the functionality of readfile(2) in various ways.

Hello Greg,

I expect readfile() to generate fanotify events FAN_OPEN_PERM, FAN_OPEN,
FAN_ACCESS_PERM, FAN_ACCESS, FAN_CLOSE_NOWRITE in this sequence.

Looking at patch 1/3 you took care of notifications. Would this deserve
testing here?

Best regards

Heinrich

>
> Also provide a simple speed test program to benchmark using readfile()
> instead of using open()/read()/close().
>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
> tools/testing/selftests/Makefile | 1 +
> tools/testing/selftests/readfile/.gitignore | 3 +
> tools/testing/selftests/readfile/Makefile | 7 +
> tools/testing/selftests/readfile/readfile.c | 285 +++++++++++++++++
> .../selftests/readfile/readfile_speed.c | 301 ++++++++++++++++++
> 5 files changed, 597 insertions(+)
> create mode 100644 tools/testing/selftests/readfile/.gitignore
> create mode 100644 tools/testing/selftests/readfile/Makefile
> create mode 100644 tools/testing/selftests/readfile/readfile.c
> create mode 100644 tools/testing/selftests/readfile/readfile_speed.c
>
> diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
> index 1195bd85af38..82359233b945 100644
> --- a/tools/testing/selftests/Makefile
> +++ b/tools/testing/selftests/Makefile
> @@ -46,6 +46,7 @@ TARGETS += ptrace
> TARGETS += openat2
> TARGETS += rseq
> TARGETS += rtc
> +TARGETS += readfile
> TARGETS += seccomp
> TARGETS += sigaltstack
> TARGETS += size
> diff --git a/tools/testing/selftests/readfile/.gitignore b/tools/testing/selftests/readfile/.gitignore
> new file mode 100644
> index 000000000000..f0e758d437e4
> --- /dev/null
> +++ b/tools/testing/selftests/readfile/.gitignore
> @@ -0,0 +1,3 @@
> +# SPDX-License-Identifier: GPL-2.0
> +readfile
> +readfile_speed
> diff --git a/tools/testing/selftests/readfile/Makefile b/tools/testing/selftests/readfile/Makefile
> new file mode 100644
> index 000000000000..1bf1bdec40f8
> --- /dev/null
> +++ b/tools/testing/selftests/readfile/Makefile
> @@ -0,0 +1,7 @@
> +# SPDX-License-Identifier: GPL-2.0
> +CFLAGS += -g -I../../../../usr/include/
> +CFLAGS += -O2 -Wl,-no-as-needed -Wall
> +
> +TEST_GEN_PROGS := readfile readfile_speed
> +
> +include ../lib.mk
> diff --git a/tools/testing/selftests/readfile/readfile.c b/tools/testing/selftests/readfile/readfile.c
> new file mode 100644
> index 000000000000..f0736c6dfa69
> --- /dev/null
> +++ b/tools/testing/selftests/readfile/readfile.c
> @@ -0,0 +1,285 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2020 Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> + * Copyright (c) 2020 The Linux Foundation
> + *
> + * Test the readfile() syscall in various ways.
> + */
> +#define _GNU_SOURCE
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <sys/syscall.h>
> +#include <sys/types.h>
> +#include <dirent.h>
> +#include <fcntl.h>
> +#include <limits.h>
> +#include <string.h>
> +#include <syscall.h>
> +
> +#include "../kselftest.h"
> +
> +//#ifndef __NR_readfile
> +//#define __NR_readfile -1
> +//#endif
> +
> +#define __NR_readfile 440
> +
> +#define TEST_FILE1 "/sys/devices/system/cpu/vulnerabilities/meltdown"
> +#define TEST_FILE2 "/sys/devices/system/cpu/vulnerabilities/spectre_v1"
> +#define TEST_FILE4 "/sys/kernel/debug/usb/devices"
> +
> +static int sys_readfile(int fd, const char *filename, unsigned char *buffer,
> + size_t bufsize, int flags)
> +{
> + return syscall(__NR_readfile, fd, filename, buffer, bufsize, flags);
> +}
> +
> +/*
> + * Test that readfile() is even in the running kernel or not.
> + */
> +static void test_readfile_supported(void)
> +{
> + const char *proc_map = "/proc/self/maps";
> + unsigned char buffer[10];
> + int retval;
> +
> + if (__NR_readfile < 0)
> + ksft_exit_skip("readfile() syscall is not defined for the kernel this test was built against\n");
> +
> + /*
> + * Do a simple test to see if the syscall really is present in the
> + * running kernel
> + */
> + retval = sys_readfile(0, proc_map, &buffer[0], sizeof(buffer), 0);
> + if (retval == -1)
> + ksft_exit_skip("readfile() syscall not present on running kernel\n");
> +
> + ksft_test_result_pass("readfile() syscall present\n");
> +}
> +
> +/*
> + * Open all files in a specific sysfs directory and read from them
> + *
> + * This tests the "openat" type functionality of opening all files relative to a
> + * directory. We don't care at the moment about the contents.
> + */
> +static void test_sysfs_files(void)
> +{
> + static unsigned char buffer[8000];
> + const char *sysfs_dir = "/sys/devices/system/cpu/vulnerabilities/";
> + struct dirent *dirent;
> + DIR *vuln_sysfs_dir;
> + int sysfs_fd;
> + int retval;
> +
> + sysfs_fd = open(sysfs_dir, O_PATH | O_DIRECTORY);
> + if (sysfs_fd == -1) {
> + ksft_test_result_skip("unable to open %s directory\n",
> + sysfs_dir);
> + return;
> + }
> +
> + vuln_sysfs_dir = opendir(sysfs_dir);
> + if (!vuln_sysfs_dir) {
> + ksft_test_result_skip("%s unable to be opened, skipping test\n");
> + return;
> + }
> +
> + ksft_print_msg("readfile: testing relative path functionality by reading files in %s\n",
> + sysfs_dir);
> + /* open all sysfs file in this directory and read the whole thing */
> + while ((dirent = readdir(vuln_sysfs_dir))) {
> + /* ignore . and .. */
> + if (strcmp(dirent->d_name, ".") == 0 ||
> + strcmp(dirent->d_name, "..") == 0)
> + continue;
> +
> + retval = sys_readfile(sysfs_fd, dirent->d_name, &buffer[0],
> + sizeof(buffer), 0);
> +
> + if (retval <= 0) {
> + ksft_test_result_fail("readfile(%s) failed with %d\n",
> + dirent->d_name, retval);
> + goto exit;
> + }
> +
> + /* cut off trailing \n character */
> + buffer[retval - 1] = 0x00;
> + ksft_print_msg(" '%s' contains \"%s\"\n", dirent->d_name,
> + buffer);
> + }
> +
> + ksft_test_result_pass("readfile() relative path functionality passed\n");
> +
> +exit:
> + closedir(vuln_sysfs_dir);
> + close(sysfs_fd);
> +}
> +
> +/* Temporary directory variables */
> +static int root_fd; /* test root directory file handle */
> +static char tmpdir[PATH_MAX];
> +
> +static void setup_tmpdir(void)
> +{
> + char *tmpdir_root;
> +
> + tmpdir_root = getenv("TMPDIR");
> + if (!tmpdir_root)
> + tmpdir_root = "/tmp";
> +
> + snprintf(tmpdir, PATH_MAX, "%s/readfile.XXXXXX", tmpdir_root);
> + if (!mkdtemp(tmpdir)) {
> + ksft_test_result_fail("mkdtemp(%s) failed\n", tmpdir);
> + ksft_exit_fail();
> + }
> +
> + root_fd = open(tmpdir, O_PATH | O_DIRECTORY);
> + if (root_fd == -1) {
> + ksft_exit_fail_msg("%s unable to be opened, error = %d\n",
> + tmpdir, root_fd);
> + ksft_exit_fail();
> + }
> +
> + ksft_print_msg("%s created to use for testing\n", tmpdir);
> +}
> +
> +static void teardown_tmpdir(void)
> +{
> + int retval;
> +
> + close(root_fd);
> +
> + retval = rmdir(tmpdir);
> + if (retval) {
> + ksft_exit_fail_msg("%s removed with return value %d\n",
> + tmpdir, retval);
> + ksft_exit_fail();
> + }
> + ksft_print_msg("%s cleaned up and removed\n", tmpdir);
> +
> +}
> +
> +static void test_filesize(size_t size)
> +{
> + char filename[PATH_MAX];
> + unsigned char *write_data;
> + unsigned char *read_data;
> + int fd;
> + int retval;
> + size_t i;
> +
> + snprintf(filename, PATH_MAX, "size-%ld", size);
> +
> + read_data = malloc(size);
> + write_data = malloc(size);
> + if (!read_data || !write_data)
> + ksft_exit_fail_msg("Unable to allocate %ld bytes\n", size);
> +
> + fd = openat(root_fd, filename, O_CREAT | O_RDWR, S_IRUSR | S_IWUSR);
> + if (fd < 0)
> + ksft_exit_fail_msg("Unable to create file %s\n", filename);
> +
> + ksft_print_msg("%s created\n", filename);
> +
> + for (i = 0; i < size; ++i)
> + write_data[i] = (unsigned char)(0xff & i);
> +
> + write(fd, write_data, size);
> + close(fd);
> +
> + retval = sys_readfile(root_fd, filename, read_data, size, 0);
> +
> + if (retval != size) {
> + ksft_test_result_fail("Read %d bytes but wanted to read %ld bytes.\n",
> + retval, size);
> + goto exit;
> + }
> +
> + if (memcmp(read_data, write_data, size) != 0) {
> + ksft_test_result_fail("Read data of buffer size %d did not match written data\n",
> + size);
> + goto exit;
> + }
> +
> + ksft_test_result_pass("readfile() of size %ld succeeded.\n", size);
> +
> +exit:
> + unlinkat(root_fd, filename, 0);
> + free(write_data);
> + free(read_data);
> +}
> +
> +
> +/*
> + * Create a bunch of differently sized files, and verify we read the correct
> + * amount of data from them.
> + */
> +static void test_filesizes(void)
> +{
> + setup_tmpdir();
> +
> + test_filesize(0x10);
> + test_filesize(0x100);
> + test_filesize(0x1000);
> + test_filesize(0x10000);
> + test_filesize(0x100000);
> + test_filesize(0x1000000);
> +
> + teardown_tmpdir();
> +
> +}
> +
> +static void readfile(const char *filename)
> +{
> +// int root_fd;
> + unsigned char buffer[16000];
> + int retval;
> +
> + memset(buffer, 0x00, sizeof(buffer));
> +
> +// root_fd = open("/", O_DIRECTORY);
> +// if (root_fd == -1)
> +// ksft_exit_fail_msg("error with root_fd\n");
> +
> + retval = sys_readfile(root_fd, filename, &buffer[0], sizeof(buffer), 0);
> +
> +// close(root_fd);
> +
> + if (retval <= 0)
> + ksft_test_result_fail("readfile() test of filename=%s failed with retval %d\n",
> + filename, retval);
> + else
> + ksft_test_result_pass("readfile() test of filename=%s succeeded with retval=%d\n",
> + filename, retval);
> +// buffer='%s'\n",
> +// filename, retval, &buffer[0]);
> +
> +}
> +
> +
> +int main(int argc, char *argv[])
> +{
> + ksft_print_header();
> + ksft_set_plan(10);
> +
> + test_readfile_supported(); // 1 test
> +
> + test_sysfs_files(); // 1 test
> +
> + test_filesizes(); // 6 tests
> +
> + setup_tmpdir();
> +
> + readfile(TEST_FILE1);
> + readfile(TEST_FILE2);
> +// readfile(TEST_FILE4);
> +
> + teardown_tmpdir();
> +
> + if (ksft_get_fail_cnt())
> + return ksft_exit_fail();
> +
> + return ksft_exit_pass();
> +}
> +
> diff --git a/tools/testing/selftests/readfile/readfile_speed.c b/tools/testing/selftests/readfile/readfile_speed.c
> new file mode 100644
> index 000000000000..11ca79163131
> --- /dev/null
> +++ b/tools/testing/selftests/readfile/readfile_speed.c
> @@ -0,0 +1,301 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2020 Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> + * Copyright (c) 2020 The Linux Foundation
> + *
> + * Tiny test program to try to benchmark the speed of the readfile syscall vs.
> + * the open/read/close sequence it can replace.
> + */
> +#define _GNU_SOURCE
> +#include <dirent.h>
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <limits.h>
> +#include <stdarg.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <sys/stat.h>
> +#include <sys/syscall.h>
> +#include <sys/types.h>
> +#include <syscall.h>
> +#include <time.h>
> +#include <unistd.h>
> +
> +/* Default test file if no one wants to pick something else */
> +#define DEFAULT_TEST_FILE "/sys/devices/system/cpu/vulnerabilities/meltdown"
> +
> +#define DEFAULT_TEST_LOOPS 1000
> +
> +#define DEFAULT_TEST_TYPE "both"
> +
> +/* Max number of bytes that will be read from the file */
> +#define TEST_BUFFER_SIZE 10000
> +static unsigned char test_buffer[TEST_BUFFER_SIZE];
> +
> +enum test_type {
> + TEST_READFILE,
> + TEST_OPENREADCLOSE,
> + TEST_BOTH,
> +};
> +
> +/* Find the readfile syscall number */
> +//#ifndef __NR_readfile
> +//#define __NR_readfile -1
> +//#endif
> +#define __NR_readfile 440
> +
> +static int sys_readfile(int fd, const char *filename, unsigned char *buffer,
> + size_t bufsize, int flags)
> +{
> + return syscall(__NR_readfile, fd, filename, buffer, bufsize, flags);
> +}
> +
> +/* Test that readfile() is even in the running kernel or not. */
> +static void test_readfile_supported(void)
> +{
> + const char *proc_map = "/proc/self/maps";
> + unsigned char buffer[10];
> + int retval;
> +
> + if (__NR_readfile < 0) {
> + fprintf(stderr,
> + "readfile() syscall is not defined for the kernel this test was built against.\n");
> + exit(1);
> + }
> +
> + /*
> + * Do a simple test to see if the syscall really is present in the
> + * running kernel
> + */
> + retval = sys_readfile(0, proc_map, &buffer[0], sizeof(buffer), 0);
> + if (retval == -1) {
> + fprintf(stderr,
> + "readfile() syscall not present on running kernel.\n");
> + exit(1);
> + }
> +}
> +
> +static inline long long get_time_ns(void)
> +{
> + struct timespec t;
> +
> + clock_gettime(CLOCK_MONOTONIC, &t);
> +
> + return (long long)t.tv_sec * 1000000000 + t.tv_nsec;
> +}
> +
> +/* taken from all-io.h from util-linux repo */
> +static inline ssize_t read_all(int fd, unsigned char *buf, size_t count)
> +{
> + ssize_t ret;
> + ssize_t c = 0;
> + int tries = 0;
> +
> + while (count > 0) {
> + ret = read(fd, buf, count);
> + if (ret <= 0) {
> + if (ret < 0 && (errno == EAGAIN || errno == EINTR) &&
> + (tries++ < 5)) {
> + usleep(250000);
> + continue;
> + }
> + return c ? c : -1;
> + }
> + tries = 0;
> + count -= ret;
> + buf += ret;
> + c += ret;
> + }
> + return c;
> +}
> +
> +static int openreadclose(const char *filename, unsigned char *buffer,
> + size_t bufsize)
> +{
> + size_t count;
> + int fd;
> +
> + fd = openat(0, filename, O_RDONLY);
> + if (fd < 0) {
> + printf("error opening %s\n", filename);
> + return fd;
> + }
> +
> + count = read_all(fd, buffer, bufsize);
> + if (count < 0) {
> + printf("Error %ld reading from %s\n", count, filename);
> + }
> +
> + close(fd);
> + return count;
> +}
> +
> +static int run_test(enum test_type test_type, const char *filename)
> +{
> + switch (test_type) {
> + case TEST_READFILE:
> + return sys_readfile(0, filename, &test_buffer[0],
> + TEST_BUFFER_SIZE, O_RDONLY);
> +
> + case TEST_OPENREADCLOSE:
> + return openreadclose(filename, &test_buffer[0],
> + TEST_BUFFER_SIZE);
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static const char * const test_names[] = {
> + [TEST_READFILE] = "readfile",
> + [TEST_OPENREADCLOSE] = "open/read/close",
> +};
> +
> +static int run_test_loop(int loops, enum test_type test_type,
> + const char *filename)
> +{
> + long long time_start;
> + long long time_end;
> + long long time_elapsed;
> + int retval = 0;
> + int i;
> +
> + fprintf(stdout,
> + "Running %s test on file %s for %d loops...\n",
> + test_names[test_type], filename, loops);
> +
> + /* Fill the cache with one run of the read first */
> + retval = run_test(test_type, filename);
> + if (retval < 0) {
> + fprintf(stderr,
> + "test %s was unable to run with error %d\n",
> + test_names[test_type], retval);
> + return retval;
> + }
> +
> + time_start = get_time_ns();
> +
> + for (i = 0; i < loops; ++i) {
> + retval = run_test(test_type, filename);
> +
> + if (retval < 0) {
> + fprintf(stderr,
> + "test failed on loop %d with error %d\n",
> + i, retval);
> + break;
> + }
> + }
> + time_end = get_time_ns();
> +
> + time_elapsed = time_end - time_start;
> +
> + fprintf(stdout, "Took %lld ns\n", time_elapsed);
> +
> + return retval;
> +}
> +
> +static int do_read_file_test(int loops, enum test_type test_type,
> + const char *filename)
> +{
> + int retval;
> +
> + if (test_type == TEST_BOTH) {
> + retval = do_read_file_test(loops, TEST_READFILE, filename);
> + retval = do_read_file_test(loops, TEST_OPENREADCLOSE, filename);
> + return retval;
> + }
> + return run_test_loop(loops, test_type, filename);
> +}
> +
> +static int check_file_present(const char *filename)
> +{
> + struct stat sb;
> + int retval;
> +
> + retval = stat(filename, &sb);
> + if (retval == -1) {
> + fprintf(stderr,
> + "filename %s is not present\n", filename);
> + return retval;
> + }
> +
> + if ((sb.st_mode & S_IFMT) != S_IFREG) {
> + fprintf(stderr,
> + "filename %s must be a real file, not anything else.\n",
> + filename);
> + return -1;
> + }
> + return 0;
> +}
> +
> +static void usage(char *progname)
> +{
> + fprintf(stderr,
> + "usage: %s [options]\n"
> + " -l loops Number of loops to run the test for.\n"
> + " default is %d\n"
> + " -t testtype Test type to run.\n"
> + " types are: readfile, openreadclose, both\n"
> + " default is %s\n"
> + " -f filename Filename to read from, full path, not relative.\n"
> + " default is %s\n",
> + progname,
> + DEFAULT_TEST_LOOPS, DEFAULT_TEST_TYPE, DEFAULT_TEST_FILE);
> +}
> +
> +int main(int argc, char *argv[])
> +{
> + char *progname;
> + char *testtype = DEFAULT_TEST_TYPE;
> + char *filename = DEFAULT_TEST_FILE;
> + int loops = DEFAULT_TEST_LOOPS;
> + enum test_type test_type;
> + int retval;
> + char c;
> +
> + progname = strrchr(argv[0], '/');
> + progname = progname ? 1+progname : argv[0];
> +
> + while (EOF != (c = getopt(argc, argv, "t:l:f:h"))) {
> + switch (c) {
> + case 'l':
> + loops = atoi(optarg);
> + break;
> +
> + case 't':
> + testtype = optarg;
> + break;
> +
> + case 'f':
> + filename = optarg;
> + break;
> +
> + case 'h':
> + usage(progname);
> + return 0;
> +
> + default:
> + usage(progname);
> + return -1;
> + }
> + }
> +
> + if (strcmp(testtype, "readfile") == 0)
> + test_type = TEST_READFILE;
> + else if (strcmp(testtype, "openreadclose") == 0)
> + test_type = TEST_OPENREADCLOSE;
> + else if (strcmp(testtype, "both") == 0)
> + test_type = TEST_BOTH;
> + else {
> + usage(progname);
> + return -1;
> + }
> +
> + test_readfile_supported();
> +
> + retval = check_file_present(filename);
> + if (retval)
> + return retval;
> +
> + return do_read_file_test(loops, test_type, filename);
> +}
>