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/*
* Check decoding of linkat syscall.
*
* Copyright (c) 2016-2024 The strace developers.
* All rights reserved.
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "tests.h"
#include "scno.h"
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <string.h>
#include "secontext.h"
#include "xlat.h"
#include "xmalloc.h"
struct xlat_data secontext_types_data[] = {
[SECONTEXT_USER] = XLAT_PAIR(SECONTEXT_USER, "user"),
[SECONTEXT_ROLE] = XLAT_PAIR(SECONTEXT_ROLE, "role"),
[SECONTEXT_TYPE] = XLAT_PAIR(SECONTEXT_TYPE, "type"),
};
struct xlat secontext_types = {
.data = secontext_types_data,
.size = ARRAY_SIZE(secontext_types_data),
.type = XT_INDEXED,
};
static void
mangle_secontext_field(const char *path, enum secontext_field field,
const char *new_val, const char *fallback_val)
{
char *orig = get_secontext_field_file(path, field);
if (!orig)
return;
const char *new = strcmp(new_val, orig) ? new_val : fallback_val;
free(orig);
int ret = update_secontext_field(path, field, new);
if (ret) {
error_msg_and_skip("Failed to mangle secontext %s for "
"'%s' to %s: %d",
sprintxval_abbrev(&secontext_types, field,
"SECONTEXT_???"),
path, new, ret);
}
}
int
main(void)
{
/*
* Make sure the current workdir of the tracee
* is different from the current workdir of the tracer.
*/
create_and_enter_subdir("linkat_subdir");
static const char sample_1[] = "linkat_sample_old";
static const char sample_2[] = "linkat_sample_new";
const long fd_old = (long) 0xdeadbeefffffffffULL;
const long fd_new = (long) 0xdeadbeeffffffffeULL;
char *my_secontext = SECONTEXT_PID_MY();
(void) unlink(sample_1);
(void) unlink(sample_2);
long rc = syscall(__NR_linkat, fd_old, sample_1, fd_new, sample_2, 0);
printf("%s%s(%d, \"%s\", %d, \"%s\", 0) = %s\n",
my_secontext, "linkat",
(int) fd_old, sample_1, (int) fd_new, sample_2,
sprintrc(rc));
rc = syscall(__NR_linkat, -100, sample_1, -100, sample_2, -1L);
printf("%s%s(%s, \"%s\", %s, \"%s\", %s) = %s\n",
my_secontext, "linkat",
"AT_FDCWD", sample_1, "AT_FDCWD", sample_2,
"AT_SYMLINK_NOFOLLOW|AT_REMOVEDIR|AT_SYMLINK_FOLLOW"
"|AT_NO_AUTOMOUNT|AT_EMPTY_PATH|AT_RECURSIVE|0xffff60ff",
sprintrc(rc));
/*
* Tests with AT_FDCWD.
*/
int fd_sample_1 = open(sample_1, O_RDONLY | O_CREAT, 0400);
if (fd_sample_1 < 0)
perror_msg_and_fail("open");
if (close(fd_sample_1))
perror_msg_and_fail("close");
char *sample_1_secontext = SECONTEXT_FILE(sample_1);
rc = syscall(__NR_linkat, -100, sample_1, -100, sample_2, 0);
/* no context printed for sample_2 since file doesn't exist yet */
printf("%s%s(AT_FDCWD, \"%s\"%s, AT_FDCWD, \"%s\", 0) = %s\n",
my_secontext, "linkat",
sample_1, sample_1_secontext,
sample_2,
sprintrc(rc));
const char *sample_2_secontext = sample_1_secontext;
rc = syscall(__NR_linkat, -100, sample_1, -100, sample_2, 0);
printf("%s%s(AT_FDCWD, \"%s\"%s, AT_FDCWD, \"%s\"%s, 0) = %s\n",
my_secontext, "linkat",
sample_1, sample_1_secontext,
sample_2, sample_2_secontext,
sprintrc(rc));
int fd_sample_2 = open(sample_2, O_RDONLY | O_CREAT, 0400);
if (fd_sample_2 < 0)
perror_msg_and_fail("open");
if (close(fd_sample_2))
perror_msg_and_fail("close");
if (*sample_1_secontext && strstr(sample_1_secontext, "!!")) {
int ret;
if ((ret = reset_secontext_file(sample_1))) {
errno = -ret;
perror_msg_and_skip("Reset secontext for '%s'",
sample_1);
}
}
free(sample_1_secontext);
#ifdef PRINT_SECONTEXT_MISMATCH
errno = 0;
mangle_secontext_field(sample_1, SECONTEXT_USER, "system_u",
"unconfined_u");
sample_1_secontext = SECONTEXT_FILE(sample_1);
# ifdef PRINT_SECONTEXT_FULL
/* The mismatch should be detected */
if (*sample_1_secontext && strstr(sample_1_secontext, "!!") == NULL)
perror_msg_and_fail("Context mismatch not detected: %s",
sample_1_secontext);
if (*sample_1_secontext && strstr(sample_1_secontext, "system_u") == NULL)
perror_msg_and_fail("Context mismatch not detected: %s",
sample_1_secontext);
# else
/* The mismatch cannot be detected since it's on user part */
if (*sample_1_secontext && strstr(sample_1_secontext, "!!") != NULL)
perror_msg_and_fail("Context mismatch detected: %s",
sample_1_secontext);
# endif
free(sample_1_secontext);
#endif
errno = 0;
mangle_secontext_field(sample_1, SECONTEXT_TYPE, "default_t",
"user_home_t");
sample_1_secontext = SECONTEXT_FILE(sample_1);
sample_2_secontext = sample_1_secontext;
#ifdef PRINT_SECONTEXT_MISMATCH
if (*sample_1_secontext && strstr(sample_1_secontext, "!!") == NULL)
perror_msg_and_fail("Context mismatch not detected: %s",
sample_1_secontext);
if (*sample_1_secontext && strstr(sample_1_secontext, "default_t") == NULL)
perror_msg_and_fail("Context mismatch not detected: %s",
sample_1_secontext);
#endif
rc = syscall(__NR_linkat, -100, sample_1, -100, sample_2, 0);
printf("%s%s(AT_FDCWD, \"%s\"%s, AT_FDCWD, \"%s\"%s, 0) = %s\n",
my_secontext, "linkat",
sample_1, sample_1_secontext,
sample_2, sample_2_secontext,
sprintrc(rc));
if (unlink(sample_2))
perror_msg_and_fail("unlink: %s", sample_2);
/*
* Tests with dirfd.
*/
int dfd_old = get_dir_fd(".");
char *cwd = get_fd_path(dfd_old);
errno = 0;
mangle_secontext_field(".", SECONTEXT_TYPE, "default_t",
"user_home_t");
char *dfd_old_secontext = SECONTEXT_FILE(".");
#ifdef PRINT_SECONTEXT_MISMATCH
if (*dfd_old_secontext && strstr(dfd_old_secontext, "!!") == NULL)
perror_msg_and_fail("Context mismatch not detected: %s",
dfd_old_secontext);
if (*dfd_old_secontext && strstr(dfd_old_secontext, "default_t") == NULL)
perror_msg_and_fail("Context mismatch not detected: %s",
dfd_old_secontext);
#endif
rc = syscall(__NR_linkat, dfd_old, sample_1, -100, sample_2, 0);
/* no context printed for sample_2 since file doesn't exist yet */
printf("%s%s(%d%s, \"%s\"%s, AT_FDCWD, \"%s\", 0) = %s\n",
my_secontext, "linkat",
dfd_old, dfd_old_secontext,
sample_1, sample_1_secontext,
sample_2,
sprintrc(rc));
rc = syscall(__NR_linkat, dfd_old, sample_1, -100, sample_2, 0);
printf("%s%s(%d%s, \"%s\"%s, AT_FDCWD, \"%s\"%s, 0) = %s\n",
my_secontext, "linkat",
dfd_old, dfd_old_secontext,
sample_1, sample_1_secontext,
sample_2, sample_2_secontext,
sprintrc(rc));
if (unlink(sample_2))
perror_msg_and_fail("unlink: %s", sample_2);
static const char new_dir[] = "new";
char *new_sample_2 = xasprintf("%s/%s", new_dir, sample_2);
(void) unlink(new_sample_2);
(void) rmdir(new_dir);
if (mkdir(new_dir, 0700))
perror_msg_and_fail("mkdir");
char *new_dir_realpath = xasprintf("%s/%s", cwd, new_dir);
char *new_dir_secontext = SECONTEXT_FILE(new_dir);
int dfd_new = get_dir_fd(new_dir);
rc = syscall(__NR_linkat, dfd_old, sample_1, dfd_new, sample_2, 0);
/* no context printed for sample_2 since file doesn't exist yet */
printf("%s%s(%d%s, \"%s\"%s, %d%s, \"%s\", 0) = %s\n",
my_secontext, "linkat",
dfd_old, dfd_old_secontext,
sample_1, sample_1_secontext,
dfd_new, new_dir_secontext,
sample_2,
sprintrc(rc));
rc = syscall(__NR_linkat, dfd_old, sample_1, dfd_new, sample_2, 0);
printf("%s%s(%d%s, \"%s\"%s, %d%s, \"%s\"%s, 0) = %s\n",
my_secontext, "linkat",
dfd_old, dfd_old_secontext,
sample_1, sample_1_secontext,
dfd_new, new_dir_secontext,
sample_2, SECONTEXT_FILE(new_sample_2),
sprintrc(rc));
char *new_sample_2_realpath = xasprintf("%s/%s", new_dir_realpath, sample_2);
/* dfd ignored when path is absolute */
if (chdir("../.."))
perror_msg_and_fail("chdir");
rc = syscall(__NR_linkat, dfd_old, sample_1, -100, new_sample_2_realpath, 0);
printf("%s%s(%d%s, \"%s\"%s, AT_FDCWD, \"%s\"%s, 0) = %s\n",
my_secontext, "linkat",
dfd_old, dfd_old_secontext,
sample_1, sample_1_secontext,
new_sample_2_realpath, SECONTEXT_FILE(new_sample_2_realpath),
sprintrc(rc));
if (fchdir(dfd_old))
perror_msg_and_fail("fchdir");
if (unlink(sample_1))
perror_msg_and_fail("unlink: %s", sample_1);
if (unlink(new_sample_2))
perror_msg_and_fail("unlink: %s", new_sample_2);
if (rmdir(new_dir))
perror_msg_and_fail("rmdir: %s", new_dir);
leave_and_remove_subdir();
puts("+++ exited with 0 +++");
return 0;
}
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