Quelle  d_path.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <test_progs.h>
#include <sys/stat.h>
#include <linux/sched.h>
#include <sys/syscall.h>

#define MAX_PATH_LEN  128
#define MAX_FILES  7

#include "test_d_path.skel.h"
#include "test_d_path_check_rdonly_mem.skel.h"
#include "test_d_path_check_types.skel.h"

/* sys_close_range is not around for long time, so let's
 * make sure we can call it on systems with older glibc
 */
#ifndef __NR_close_range
#ifdef __alpha__
#define __NR_close_range 546
#else
#define __NR_close_range 436
#endif
#endif

static int duration;

static struct {
 __u32 cnt;
 char paths[MAX_FILES][MAX_PATH_LEN];
} src;

static int set_pathname(int fd, pid_t pid)
{
 char buf[MAX_PATH_LEN];

 snprintf(buf, MAX_PATH_LEN, "/proc/%d/fd/%d", pid, fd);
 return readlink(buf, src.paths[src.cnt++], MAX_PATH_LEN);
}

static int trigger_fstat_events(pid_t pid)
{
 int sockfd = -1, procfd = -1, devfd = -1;
 int localfd = -1, indicatorfd = -1;
 int pipefd[2] = { -1, -1 };
 struct stat fileStat;
 int ret = -1;

 /* unmountable pseudo-filesystems */
 if (CHECK(pipe(pipefd) < 0, "trigger", "pipe failed\n"))
  return ret;
 /* unmountable pseudo-filesystems */
 sockfd = socket(AF_INET, SOCK_STREAM, 0);
 if (CHECK(sockfd < 0, "trigger", "socket failed\n"))
  goto out_close;
 /* mountable pseudo-filesystems */
 procfd = open("/proc/self/comm", O_RDONLY);
 if (CHECK(procfd < 0, "trigger", "open /proc/self/comm failed\n"))
  goto out_close;
 devfd = open("/dev/urandom", O_RDONLY);
 if (CHECK(devfd < 0, "trigger", "open /dev/urandom failed\n"))
  goto out_close;
 localfd = open("/tmp/d_path_loadgen.txt", O_CREAT | O_RDONLY, 0644);
 if (CHECK(localfd < 0, "trigger", "open /tmp/d_path_loadgen.txt failed\n"))
  goto out_close;
 /* bpf_d_path will return path with (deleted) */
 remove("/tmp/d_path_loadgen.txt");
 indicatorfd = open("/tmp/", O_PATH);
 if (CHECK(indicatorfd < 0, "trigger", "open /tmp/ failed\n"))
  goto out_close;

 ret = set_pathname(pipefd[0], pid);
 if (CHECK(ret < 0, "trigger", "set_pathname failed for pipe[0]\n"))
  goto out_close;
 ret = set_pathname(pipefd[1], pid);
 if (CHECK(ret < 0, "trigger", "set_pathname failed for pipe[1]\n"))
  goto out_close;
 ret = set_pathname(sockfd, pid);
 if (CHECK(ret < 0, "trigger", "set_pathname failed for socket\n"))
  goto out_close;
 ret = set_pathname(procfd, pid);
 if (CHECK(ret < 0, "trigger", "set_pathname failed for proc\n"))
  goto out_close;
 ret = set_pathname(devfd, pid);
 if (CHECK(ret < 0, "trigger", "set_pathname failed for dev\n"))
  goto out_close;
 ret = set_pathname(localfd, pid);
 if (CHECK(ret < 0, "trigger", "set_pathname failed for file\n"))
  goto out_close;
 ret = set_pathname(indicatorfd, pid);
 if (CHECK(ret < 0, "trigger", "set_pathname failed for dir\n"))
  goto out_close;

 /* triggers vfs_getattr */
 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:
 /* sys_close no longer triggers filp_close, but we can
 * call sys_close_range instead which still does
 */
#define close(fd) syscall(__NR_close_range, fd, fd, 0)

 close(pipefd[0]);
 close(pipefd[1]);
 close(sockfd);
 close(procfd);
 close(devfd);
 close(localfd);
 close(indicatorfd);

#undef close
 return ret;
}

static void test_d_path_basic(void)
{
 struct test_d_path__bss *bss;
 struct test_d_path *skel;
 int err;

 skel = test_d_path__open_and_load();
 if (CHECK(!skel, "setup", "d_path skeleton failed\n"))
  goto cleanup;

 err = test_d_path__attach(skel);
 if (CHECK(err, "setup", "attach failed: %d\n", err))
  goto cleanup;

 bss = skel->bss;
 bss->my_pid = getpid();

 err = trigger_fstat_events(bss->my_pid);
 if (err < 0)
  goto cleanup;

 if (CHECK(!bss->called_stat,
    "stat",
    "trampoline for security_inode_getattr was not called\n"))
  goto cleanup;

 if (CHECK(!bss->called_close,
    "close",
    "trampoline for filp_close was not called\n"))
  goto cleanup;

 for (int i = 0; i < MAX_FILES; i++) {
  CHECK(strncmp(src.paths[i], bss->paths_stat[i], MAX_PATH_LEN),
        "check",
        "failed to get stat path[%d]: %s vs %s\n",
        i, src.paths[i], bss->paths_stat[i]);
  CHECK(strncmp(src.paths[i], bss->paths_close[i], MAX_PATH_LEN),
        "check",
        "failed to get close path[%d]: %s vs %s\n",
        i, src.paths[i], bss->paths_close[i]);
  /* The d_path helper returns size plus NUL char, hence + 1 */
  CHECK(bss->rets_stat[i] != strlen(bss->paths_stat[i]) + 1,
        "check",
        "failed to match stat return [%d]: %d vs %zd [%s]\n",
        i, bss->rets_stat[i], strlen(bss->paths_stat[i]) + 1,
        bss->paths_stat[i]);
  CHECK(bss->rets_close[i] != strlen(bss->paths_stat[i]) + 1,
        "check",
        "failed to match stat return [%d]: %d vs %zd [%s]\n",
        i, bss->rets_close[i], strlen(bss->paths_close[i]) + 1,
        bss->paths_stat[i]);
 }

cleanup:
 test_d_path__destroy(skel);
}

static void test_d_path_check_rdonly_mem(void)
{
 struct test_d_path_check_rdonly_mem *skel;

 skel = test_d_path_check_rdonly_mem__open_and_load();
 ASSERT_ERR_PTR(skel, "unexpected_load_overwriting_rdonly_mem");

 test_d_path_check_rdonly_mem__destroy(skel);
}

static void test_d_path_check_types(void)
{
 struct test_d_path_check_types *skel;

 skel = test_d_path_check_types__open_and_load();
 ASSERT_ERR_PTR(skel, "unexpected_load_passing_wrong_type");

 test_d_path_check_types__destroy(skel);
}

void test_d_path(void)
{
 if (test__start_subtest("basic"))
  test_d_path_basic();

 if (test__start_subtest("check_rdonly_mem"))
  test_d_path_check_rdonly_mem();

 if (test__start_subtest("check_alloc_mem"))
  test_d_path_check_types();
}