test/personality.c

/* SPDX-License-Identifier: MIT */
/*
 * Description: test if personalities work
 *
 */
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>

#include "liburing.h"

#define FNAME	"/tmp/.tmp.access"
#define USE_UID	1000

static int no_personality;

static int open_file(struct io_uring *ring, int cred_id, int with_link)
{
	struct io_uring_cqe *cqe;
	struct io_uring_sqe *sqe;
	int ret, i, to_submit = 1;

	if (with_link) {
		sqe = io_uring_get_sqe(ring);
		io_uring_prep_nop(sqe);
		sqe->flags |= IOSQE_IO_LINK;
		sqe->user_data = 1;
		to_submit++;
	}

	sqe = io_uring_get_sqe(ring);
	io_uring_prep_openat(sqe, -1, FNAME, O_RDONLY, 0);
	sqe->user_data = 2;

	if (cred_id != -1)
		sqe->personality = cred_id;

	ret = io_uring_submit(ring);
	if (ret != to_submit) {
		fprintf(stderr, "submit got: %d\n", ret);
		goto err;
	}

	for (i = 0; i < to_submit; i++) {
		ret = io_uring_wait_cqe(ring, &cqe);
		if (ret < 0) {
			fprintf(stderr, "wait completion %d\n", ret);
			goto err;
		}

		ret = cqe->res;
		io_uring_cqe_seen(ring, cqe);
	}
err:
	return ret;
}

static int test_personality(struct io_uring *ring)
{
	int ret, cred_id;

	ret = io_uring_register_personality(ring);
	if (ret < 0) {
		if (ret == -EINVAL) {
			fprintf(stdout, "Personalities not supported, skipping\n");
			no_personality = 1;
			goto out;
		}
		fprintf(stderr, "register_personality: %d\n", ret);
		goto err;
	}
	cred_id = ret;

	/* create file only owner can open */
	ret = open(FNAME, O_RDONLY | O_CREAT, 0600);
	if (ret < 0) {
		perror("open");
		goto err;
	}
	close(ret);

	/* verify we can open it */
	ret = open_file(ring, -1, 0);
	if (ret < 0) {
		fprintf(stderr, "current open got: %d\n", ret);
		goto err;
	}

	if (seteuid(USE_UID) < 0) {
		fprintf(stdout, "Can't switch to UID %u, skipping\n", USE_UID);
		goto out;
	}

	/* verify we can't open it with current credentials */
	ret = open_file(ring, -1, 0);
	if (ret != -EACCES) {
		fprintf(stderr, "open got: %d\n", ret);
		goto err;
	}

	/* verify we can open with registered credentials */
	ret = open_file(ring, cred_id, 0);
	if (ret < 0) {
		fprintf(stderr, "credential open: %d\n", ret);
		goto err;
	}
	close(ret);

	/* verify we can open with registered credentials and as a link */
	ret = open_file(ring, cred_id, 1);
	if (ret < 0) {
		fprintf(stderr, "credential open: %d\n", ret);
		goto err;
	}

	if (seteuid(0))
		perror("seteuid");

	ret = io_uring_unregister_personality(ring, cred_id);
	if (ret) {
		fprintf(stderr, "register_personality: %d\n", ret);
		goto err;
	}

out:
	unlink(FNAME);
	return 0;
err:
	unlink(FNAME);
	return 1;
}

static int test_invalid_personality(struct io_uring *ring)
{
	int ret;

	ret = open_file(ring, 2, 0);
	if (ret != -EINVAL) {
		fprintf(stderr, "invalid personality got: %d\n", ret);
		goto err;
	}
	return 0;
err:
	return 1;
}

static int test_invalid_unregister(struct io_uring *ring)
{
	int ret;

	ret = io_uring_unregister_personality(ring, 2);
	if (ret != -EINVAL) {
		fprintf(stderr, "invalid personality unregister got: %d\n", ret);
		goto err;
	}
	return 0;
err:
	return 1;
}

int main(int argc, char *argv[])
{
	struct io_uring ring;
	int ret;

	if (geteuid()) {
		fprintf(stderr, "Not root, skipping\n");
		return 0;
	}

	ret = io_uring_queue_init(8, &ring, 0);
	if (ret) {
		fprintf(stderr, "ring setup failed: %d\n", ret);
		return 1;
	}

	ret = test_personality(&ring);
	if (ret) {
		fprintf(stderr, "test_personality failed\n");
		return ret;
	}
	if (no_personality)
		return 0;

	ret = test_invalid_personality(&ring);
	if (ret) {
		fprintf(stderr, "test_invalid_personality failed\n");
		return ret;
	}

	ret = test_invalid_unregister(&ring);
	if (ret) {
		fprintf(stderr, "test_invalid_unregister failed\n");
		return ret;
	}

	return 0;
}