diff options
Diffstat (limited to 'tools/testing/selftests/bpf/prog_tests/lsm_bdev.c')
| -rw-r--r-- | tools/testing/selftests/bpf/prog_tests/lsm_bdev.c | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/lsm_bdev.c b/tools/testing/selftests/bpf/prog_tests/lsm_bdev.c new file mode 100644 index 000000000000..a970798e1173 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/lsm_bdev.c @@ -0,0 +1,221 @@ +// 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); +} |