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Commit db86da7c authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

userns: Unbreak the unprivileged remount tests 



A security fix in caused the way the unprivileged remount tests were
using user namespaces to break.  Tweak the way user namespaces are
being used so the test works again.

Cc: stable@vger.kernel.org
Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
parent 36476bea

tools/testing/selftests/mount/unprivileged-remount-test.c

+24 −8
Original line number Diff line number Diff line
@@ -53,17 +53,14 @@ static void die(char *fmt, ...) 
	exit(EXIT_FAILURE);

}



static void write_file(char *filename, char *fmt, ...)

static void vmaybe_write_file(bool enoent_ok, char *filename, char *fmt, va_list ap)

{

	char buf[4096];

	int fd;

	ssize_t written;

	int buf_len;

	va_list ap;



	va_start(ap, fmt);

	buf_len = vsnprintf(buf, sizeof(buf), fmt, ap);

	va_end(ap);

	if (buf_len < 0) {

		die("vsnprintf failed: %s\n",

		    strerror(errno));
@@ -74,6 +71,8 @@ static void write_file(char *filename, char *fmt, ...) 


	fd = open(filename, O_WRONLY);

	if (fd < 0) {

		if ((errno == ENOENT) && enoent_ok)

			return;

		die("open of %s failed: %s\n",

		    filename, strerror(errno));

	}
@@ -92,6 +91,26 @@ static void write_file(char *filename, char *fmt, ...) 
	}

}



static void maybe_write_file(char *filename, char *fmt, ...)

{

	va_list ap;



	va_start(ap, fmt);

	vmaybe_write_file(true, filename, fmt, ap);

	va_end(ap);



}



static void write_file(char *filename, char *fmt, ...)

{

	va_list ap;



	va_start(ap, fmt);

	vmaybe_write_file(false, filename, fmt, ap);

	va_end(ap);



}



static int read_mnt_flags(const char *path)

{

	int ret;
@@ -144,13 +163,10 @@ static void create_and_enter_userns(void) 
			strerror(errno));

	}



	maybe_write_file("/proc/self/setgroups", "deny");

	write_file("/proc/self/uid_map", "0 %d 1", uid);

	write_file("/proc/self/gid_map", "0 %d 1", gid);



	if (setgroups(0, NULL) != 0) {

		die("setgroups failed: %s\n",

			strerror(errno));

	}

	if (setgid(0) != 0) {

		die ("setgid(0) failed %s\n",

			strerror(errno));