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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2026 Christian Brauner <brauner@kernel.org> */
/*
* Test BPF LSM block device integrity hooks with dm-verity.
*
* Creates a dm-verity device over loopback, which triggers
* security_bdev_setintegrity() during verity_preresume().
* Verifies that the BPF program correctly tracks the integrity
* metadata in its hashmap.
*/
#define _GNU_SOURCE
#include <test_progs.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include "lsm_bdev.skel.h"
/* Must match the definition in progs/lsm_bdev.c. */
struct verity_info {
__u8 has_roothash;
__u8 sig_valid;
__u32 setintegrity_cnt;
};
#define DATA_SIZE_MB 8
#define HASH_SIZE_MB 1
#define DM_NAME "bpf_test_verity"
#define DM_DEV_PATH "/dev/mapper/" DM_NAME
/* Run a command and optionally capture the first line of stdout. */
static int run_cmd(const char *cmd, char *out, size_t out_sz)
{
FILE *fp;
int ret;
fp = popen(cmd, "r");
if (!fp)
return -1;
if (out && out_sz > 0) {
if (!fgets(out, out_sz, fp))
out[0] = '\0';
/* strip trailing newline */
out[strcspn(out, "\n")] = '\0';
}
ret = pclose(fp);
return WIFEXITED(ret) ? WEXITSTATUS(ret) : -1;
}
static bool has_prerequisites(void)
{
if (getuid() != 0) {
printf("SKIP: must be root\n");
return false;
}
if (run_cmd("modprobe loop 2>/dev/null", NULL, 0) &&
run_cmd("ls /dev/loop-control 2>/dev/null", NULL, 0)) {
printf("SKIP: no loop device support\n");
return false;
}
if (run_cmd("modprobe dm-verity 2>/dev/null", NULL, 0) &&
run_cmd("dmsetup targets 2>/dev/null | grep -q verity", NULL, 0)) {
printf("SKIP: dm-verity module not available\n");
return false;
}
if (run_cmd("which veritysetup >/dev/null 2>&1", NULL, 0)) {
printf("SKIP: veritysetup not found\n");
return false;
}
return true;
}
void test_lsm_bdev(void)
{
char data_img[] = "/tmp/bpf_verity_data_XXXXXX";
char hash_img[] = "/tmp/bpf_verity_hash_XXXXXX";
char data_loop[64] = {};
char hash_loop[64] = {};
char roothash[256] = {};
char cmd[512];
int data_fd = -1, hash_fd = -1;
struct lsm_bdev *skel = NULL;
struct verity_info val;
struct stat st;
__u32 dev_key;
int err;
if (!has_prerequisites()) {
test__skip();
return;
}
/* Clean up any stale device from a previous crashed run. */
snprintf(cmd, sizeof(cmd), "dmsetup remove %s 2>/dev/null", DM_NAME);
run_cmd(cmd, NULL, 0);
/* Create temporary image files. */
data_fd = mkstemp(data_img);
if (!ASSERT_OK_FD(data_fd, "mkstemp data"))
return;
hash_fd = mkstemp(hash_img);
if (!ASSERT_OK_FD(hash_fd, "mkstemp hash"))
goto cleanup;
if (!ASSERT_OK(ftruncate(data_fd, DATA_SIZE_MB * 1024 * 1024),
"truncate data"))
goto cleanup;
if (!ASSERT_OK(ftruncate(hash_fd, HASH_SIZE_MB * 1024 * 1024),
"truncate hash"))
goto cleanup;
close(data_fd);
data_fd = -1;
close(hash_fd);
hash_fd = -1;
/* Set up loop devices. */
snprintf(cmd, sizeof(cmd),
"losetup --find --show %s 2>/dev/null", data_img);
if (!ASSERT_OK(run_cmd(cmd, data_loop, sizeof(data_loop)),
"losetup data"))
goto teardown;
snprintf(cmd, sizeof(cmd),
"losetup --find --show %s 2>/dev/null", hash_img);
if (!ASSERT_OK(run_cmd(cmd, hash_loop, sizeof(hash_loop)),
"losetup hash"))
goto teardown;
/* Format the dm-verity device and capture the root hash. */
snprintf(cmd, sizeof(cmd),
"veritysetup format %s %s 2>/dev/null | "
"grep -i 'root hash' | awk '{print $NF}'",
data_loop, hash_loop);
if (!ASSERT_OK(run_cmd(cmd, roothash, sizeof(roothash)),
"veritysetup format"))
goto teardown;
if (!ASSERT_GT((int)strlen(roothash), 0, "roothash not empty"))
goto teardown;
/* Load and attach BPF program before activating dm-verity. */
skel = lsm_bdev__open_and_load();
if (!ASSERT_OK_PTR(skel, "skel open_and_load"))
goto teardown;
err = lsm_bdev__attach(skel);
if (!ASSERT_OK(err, "skel attach"))
goto teardown;
/* Activate dm-verity — triggers verity_preresume() hooks. */
snprintf(cmd, sizeof(cmd),
"veritysetup open %s %s %s %s 2>/dev/null",
data_loop, DM_NAME, hash_loop, roothash);
if (!ASSERT_OK(run_cmd(cmd, NULL, 0), "veritysetup open"))
goto teardown;
/* Get the dm device's dev_t. */
if (!ASSERT_OK(stat(DM_DEV_PATH, &st), "stat dm dev"))
goto remove_dm;
dev_key = (__u32)st.st_rdev;
/* Look up the device in the BPF map and verify. */
err = bpf_map__lookup_elem(skel->maps.verity_devices,
&dev_key, sizeof(dev_key),
&val, sizeof(val), 0);
if (!ASSERT_OK(err, "map lookup"))
goto remove_dm;
ASSERT_EQ(val.has_roothash, 1, "has_roothash");
ASSERT_EQ(val.sig_valid, 0, "sig_valid (unsigned)");
/*
* verity_preresume() always calls security_bdev_setintegrity()
* for the roothash. The signature-validity call only happens
* when CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG is enabled.
*/
ASSERT_GE(val.setintegrity_cnt, 1, "setintegrity_cnt min");
ASSERT_LE(val.setintegrity_cnt, 2, "setintegrity_cnt max");
/* Verify that the alloc hook fired at least once. */
ASSERT_GT(skel->bss->alloc_count, 0, "alloc_count");
remove_dm:
snprintf(cmd, sizeof(cmd), "dmsetup remove %s 2>/dev/null", DM_NAME);
run_cmd(cmd, NULL, 0);
teardown:
if (data_loop[0]) {
snprintf(cmd, sizeof(cmd), "losetup -d %s 2>/dev/null",
data_loop);
run_cmd(cmd, NULL, 0);
}
if (hash_loop[0]) {
snprintf(cmd, sizeof(cmd), "losetup -d %s 2>/dev/null",
hash_loop);
run_cmd(cmd, NULL, 0);
}
cleanup:
lsm_bdev__destroy(skel);
if (data_fd >= 0)
close(data_fd);
if (hash_fd >= 0)
close(hash_fd);
unlink(data_img);
unlink(hash_img);
}
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