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mnt: Update unprivileged remount test

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- MNT_NODEV should be irrelevant except when reading back mount flags,
  no longer specify MNT_NODEV on remount.

- Test MNT_NODEV on devpts where it is meaningful even for unprivileged mounts.

- Add a test to verify that remount of a prexisting mount with the same flags
  is allowed and does not change those flags.

- Cleanup up the definitions of MS_REC, MS_RELATIME, MS_STRICTATIME that are used
  when the code is built in an environment without them.

- Correct the test error messages when tests fail.  There were not 5 tests
  that tested MS_RELATIME.

Cc: stable@vger.kernel.org
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2014-08-22 16:39:03 -05:00
parent 3e1866410f
commit 4a44a19b47
1 changed files with 142 additions and 30 deletions
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172
tools/testing/selftests/mount/unprivileged-remount-test.c
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@ -6,6 +6,8 @@
#include <sys/types.h> #include <sys/types.h>
#include <sys/mount.h> #include <sys/mount.h>
#include <sys/wait.h> #include <sys/wait.h>
#include <sys/vfs.h>
#include <sys/statvfs.h>
#include <stdlib.h> #include <stdlib.h>
#include <unistd.h> #include <unistd.h>
#include <fcntl.h> #include <fcntl.h>
@ -32,11 +34,14 @@
# define CLONE_NEWPID 0x20000000 # define CLONE_NEWPID 0x20000000
#endif #endif
#ifndef MS_REC
# define MS_REC 16384
#endif
#ifndef MS_RELATIME #ifndef MS_RELATIME
#define MS_RELATIME (1 << 21) # define MS_RELATIME (1 << 21)
#endif #endif
#ifndef MS_STRICTATIME #ifndef MS_STRICTATIME
#define MS_STRICTATIME (1 << 24) # define MS_STRICTATIME (1 << 24)
#endif #endif
static void die(char *fmt, ...) static void die(char *fmt, ...)
@ -87,6 +92,45 @@ static void write_file(char *filename, char *fmt, ...)
} }
} }
static int read_mnt_flags(const char *path)
{
int ret;
struct statvfs stat;
int mnt_flags;
ret = statvfs(path, &stat);
if (ret != 0) {
die("statvfs of %s failed: %s\n",
path, strerror(errno));
}
if (stat.f_flag & ~(ST_RDONLY | ST_NOSUID | ST_NODEV | \
ST_NOEXEC | ST_NOATIME | ST_NODIRATIME | ST_RELATIME | \
ST_SYNCHRONOUS | ST_MANDLOCK)) {
die("Unrecognized mount flags\n");
}
mnt_flags = 0;
if (stat.f_flag & ST_RDONLY)
mnt_flags |= MS_RDONLY;
if (stat.f_flag & ST_NOSUID)
mnt_flags |= MS_NOSUID;
if (stat.f_flag & ST_NODEV)
mnt_flags |= MS_NODEV;
if (stat.f_flag & ST_NOEXEC)
mnt_flags |= MS_NOEXEC;
if (stat.f_flag & ST_NOATIME)
mnt_flags |= MS_NOATIME;
if (stat.f_flag & ST_NODIRATIME)
mnt_flags |= MS_NODIRATIME;
if (stat.f_flag & ST_RELATIME)
mnt_flags |= MS_RELATIME;
if (stat.f_flag & ST_SYNCHRONOUS)
mnt_flags |= MS_SYNCHRONOUS;
if (stat.f_flag & ST_MANDLOCK)
mnt_flags |= ST_MANDLOCK;
return mnt_flags;
}
static void create_and_enter_userns(void) static void create_and_enter_userns(void)
{ {
uid_t uid; uid_t uid;
@ -118,7 +162,8 @@ static void create_and_enter_userns(void)
} }
static static
bool test_unpriv_remount(int mount_flags, int remount_flags, int invalid_flags) bool test_unpriv_remount(const char *fstype, const char *mount_options,
int mount_flags, int remount_flags, int invalid_flags)
{ {
pid_t child; pid_t child;
@ -151,9 +196,11 @@ bool test_unpriv_remount(int mount_flags, int remount_flags, int invalid_flags)
strerror(errno)); strerror(errno));
} }
if (mount("testing", "/tmp", "ramfs", mount_flags, NULL) != 0) { if (mount("testing", "/tmp", fstype, mount_flags, mount_options) != 0) {
die("mount of /tmp failed: %s\n", die("mount of %s with options '%s' on /tmp failed: %s\n",
strerror(errno)); fstype,
mount_options? mount_options : "",
strerror(errno));
} }
create_and_enter_userns(); create_and_enter_userns();
@ -181,62 +228,127 @@ bool test_unpriv_remount(int mount_flags, int remount_flags, int invalid_flags)
static bool test_unpriv_remount_simple(int mount_flags) static bool test_unpriv_remount_simple(int mount_flags)
{ {
return test_unpriv_remount(mount_flags, mount_flags, 0); return test_unpriv_remount("ramfs", NULL, mount_flags, mount_flags, 0);
} }
static bool test_unpriv_remount_atime(int mount_flags, int invalid_flags) static bool test_unpriv_remount_atime(int mount_flags, int invalid_flags)
{ {
return test_unpriv_remount(mount_flags, mount_flags, invalid_flags); return test_unpriv_remount("ramfs", NULL, mount_flags, mount_flags,
invalid_flags);
}
static bool test_priv_mount_unpriv_remount(void)
{
pid_t child;
int ret;
const char *orig_path = "/dev";
const char *dest_path = "/tmp";
int orig_mnt_flags, remount_mnt_flags;
child = fork();
if (child == -1) {
die("fork failed: %s\n",
strerror(errno));
}
if (child != 0) { /* parent */
pid_t pid;
int status;
pid = waitpid(child, &status, 0);
if (pid == -1) {
die("waitpid failed: %s\n",
strerror(errno));
}
if (pid != child) {
die("waited for %d got %d\n",
child, pid);
}
if (!WIFEXITED(status)) {
die("child did not terminate cleanly\n");
}
return WEXITSTATUS(status) == EXIT_SUCCESS ? true : false;
}
orig_mnt_flags = read_mnt_flags(orig_path);
create_and_enter_userns();
ret = unshare(CLONE_NEWNS);
if (ret != 0) {
die("unshare(CLONE_NEWNS) failed: %s\n",
strerror(errno));
}
ret = mount(orig_path, dest_path, "bind", MS_BIND | MS_REC, NULL);
if (ret != 0) {
die("recursive bind mount of %s onto %s failed: %s\n",
orig_path, dest_path, strerror(errno));
}
ret = mount(dest_path, dest_path, "none",
MS_REMOUNT | MS_BIND | orig_mnt_flags , NULL);
if (ret != 0) {
/* system("cat /proc/self/mounts"); */
die("remount of /tmp failed: %s\n",
strerror(errno));
}
remount_mnt_flags = read_mnt_flags(dest_path);
if (orig_mnt_flags != remount_mnt_flags) {
die("Mount flags unexpectedly changed during remount of %s originally mounted on %s\n",
dest_path, orig_path);
}
exit(EXIT_SUCCESS);
} }
int main(int argc, char **argv) int main(int argc, char **argv)
{ {
if (!test_unpriv_remount_simple(MS_RDONLY|MS_NODEV)) { if (!test_unpriv_remount_simple(MS_RDONLY)) {
die("MS_RDONLY malfunctions\n"); die("MS_RDONLY malfunctions\n");
} }
if (!test_unpriv_remount_simple(MS_NODEV)) { if (!test_unpriv_remount("devpts", "newinstance", MS_NODEV, MS_NODEV, 0)) {
die("MS_NODEV malfunctions\n"); die("MS_NODEV malfunctions\n");
} }
if (!test_unpriv_remount_simple(MS_NOSUID|MS_NODEV)) { if (!test_unpriv_remount_simple(MS_NOSUID)) {
die("MS_NOSUID malfunctions\n"); die("MS_NOSUID malfunctions\n");
} }
if (!test_unpriv_remount_simple(MS_NOEXEC|MS_NODEV)) { if (!test_unpriv_remount_simple(MS_NOEXEC)) {
die("MS_NOEXEC malfunctions\n"); die("MS_NOEXEC malfunctions\n");
} }
if (!test_unpriv_remount_atime(MS_RELATIME|MS_NODEV, if (!test_unpriv_remount_atime(MS_RELATIME,
MS_NOATIME|MS_NODEV)) MS_NOATIME))
{ {
die("MS_RELATIME malfunctions\n"); die("MS_RELATIME malfunctions\n");
} }
if (!test_unpriv_remount_atime(MS_STRICTATIME|MS_NODEV, if (!test_unpriv_remount_atime(MS_STRICTATIME,
MS_NOATIME|MS_NODEV)) MS_NOATIME))
{ {
die("MS_STRICTATIME malfunctions\n"); die("MS_STRICTATIME malfunctions\n");
} }
if (!test_unpriv_remount_atime(MS_NOATIME|MS_NODEV, if (!test_unpriv_remount_atime(MS_NOATIME,
MS_STRICTATIME|MS_NODEV)) MS_STRICTATIME))
{ {
die("MS_RELATIME malfunctions\n"); die("MS_NOATIME malfunctions\n");
} }
if (!test_unpriv_remount_atime(MS_RELATIME|MS_NODIRATIME|MS_NODEV, if (!test_unpriv_remount_atime(MS_RELATIME|MS_NODIRATIME,
MS_NOATIME|MS_NODEV)) MS_NOATIME))
{ {
die("MS_RELATIME malfunctions\n"); die("MS_RELATIME|MS_NODIRATIME malfunctions\n");
} }
if (!test_unpriv_remount_atime(MS_STRICTATIME|MS_NODIRATIME|MS_NODEV, if (!test_unpriv_remount_atime(MS_STRICTATIME|MS_NODIRATIME,
MS_NOATIME|MS_NODEV)) MS_NOATIME))
{ {
die("MS_RELATIME malfunctions\n"); die("MS_STRICTATIME|MS_NODIRATIME malfunctions\n");
} }
if (!test_unpriv_remount_atime(MS_NOATIME|MS_NODIRATIME|MS_NODEV, if (!test_unpriv_remount_atime(MS_NOATIME|MS_NODIRATIME,
MS_STRICTATIME|MS_NODEV)) MS_STRICTATIME))
{ {
die("MS_RELATIME malfunctions\n"); die("MS_NOATIME|MS_DIRATIME malfunctions\n");
} }
if (!test_unpriv_remount(MS_STRICTATIME|MS_NODEV, MS_NODEV, if (!test_unpriv_remount("ramfs", NULL, MS_STRICTATIME, 0, MS_NOATIME))
MS_NOATIME|MS_NODEV))
{ {
die("Default atime malfunctions\n"); die("Default atime malfunctions\n");
} }
if (!test_priv_mount_unpriv_remount()) {
die("Mount flags unexpectedly changed after remount\n");
}
return EXIT_SUCCESS; return EXIT_SUCCESS;
} }