// SPDX-License-Identifier: GPL-2.0

/*
 * Copyright (C) 2020 Google LLC.
 */

#include <asm-generic/errno-base.h>
#include <sys/stat.h>
#include <test_progs.h>
#include <linux/limits.h>

#include "local_storage.skel.h"
#include "network_helpers.h"
#include "task_local_storage_helpers.h"

#define TEST_STORAGE_VALUE 0xbeefdead

struct storage {
        void *inode;
        unsigned int value;
};

/* Fork and exec the provided rm binary and return the exit code of the
 * forked process and its pid.
 */
static int run_self_unlink(struct local_storage *skel, const char *rm_path)
{
        int child_pid, child_status, ret;
        int null_fd;

        child_pid = fork();
        if (child_pid == 0) {
                null_fd = open("/dev/null", O_WRONLY);
                dup2(null_fd, STDOUT_FILENO);
                dup2(null_fd, STDERR_FILENO);
                close(null_fd);

                skel->bss->monitored_pid = getpid();
                /* Use the copied /usr/bin/rm to delete itself
                 * /tmp/copy_of_rm /tmp/copy_of_rm.
                 */
                ret = execlp(rm_path, rm_path, rm_path, NULL);
                if (ret)
                        exit(errno);
        } else if (child_pid > 0) {
                waitpid(child_pid, &child_status, 0);
                ASSERT_EQ(skel->data->task_storage_result, 0, "task_storage_result");
                return WEXITSTATUS(child_status);
        }

        return -EINVAL;
}

static bool check_syscall_operations(int map_fd, int obj_fd)
{
        struct storage val = { .value = TEST_STORAGE_VALUE },
                       lookup_val = { .value = 0 };
        int err;

        /* Looking up an existing element should fail initially */
        err = bpf_map_lookup_elem_flags(map_fd, &obj_fd, &lookup_val, 0);
        if (!ASSERT_EQ(err, -ENOENT, "bpf_map_lookup_elem"))
                return false;

        /* Create a new element */
        err = bpf_map_update_elem(map_fd, &obj_fd, &val, BPF_NOEXIST);
        if (!ASSERT_OK(err, "bpf_map_update_elem"))
                return false;

        /* Lookup the newly created element */
        err = bpf_map_lookup_elem_flags(map_fd, &obj_fd, &lookup_val, 0);
        if (!ASSERT_OK(err, "bpf_map_lookup_elem"))
                return false;

        /* Check the value of the newly created element */
        if (!ASSERT_EQ(lookup_val.value, val.value, "bpf_map_lookup_elem"))
                return false;

        err = bpf_map_delete_elem(map_fd, &obj_fd);
        if (!ASSERT_OK(err, "bpf_map_delete_elem()"))
                return false;

        /* The lookup should fail, now that the element has been deleted */
        err = bpf_map_lookup_elem_flags(map_fd, &obj_fd, &lookup_val, 0);
        if (!ASSERT_EQ(err, -ENOENT, "bpf_map_lookup_elem"))
                return false;

        return true;
}

void test_test_local_storage(void)
{
        char tmp_dir_path[] = "/tmp/local_storageXXXXXX";
        int err, serv_sk = -1, task_fd = -1, rm_fd = -1;
        struct local_storage *skel = NULL;
        char tmp_exec_path[64];
        char cmd[256];

        skel = local_storage__open_and_load();
        if (!ASSERT_OK_PTR(skel, "skel_load"))
                goto close_prog;

        err = local_storage__attach(skel);
        if (!ASSERT_OK(err, "attach"))
                goto close_prog;

        task_fd = sys_pidfd_open(getpid(), 0);
        if (!ASSERT_GE(task_fd, 0, "pidfd_open"))
                goto close_prog;

        if (!check_syscall_operations(bpf_map__fd(skel->maps.task_storage_map),
                                      task_fd))
                goto close_prog;

        if (!ASSERT_OK_PTR(mkdtemp(tmp_dir_path), "mkdtemp"))
                goto close_prog;

        snprintf(tmp_exec_path, sizeof(tmp_exec_path), "%s/copy_of_rm",
                 tmp_dir_path);
        snprintf(cmd, sizeof(cmd), "cp /bin/rm %s", tmp_exec_path);
        if (!ASSERT_OK(system(cmd), "system(cp)"))
                goto close_prog_rmdir;

        rm_fd = open(tmp_exec_path, O_RDONLY);
        if (!ASSERT_GE(rm_fd, 0, "open(tmp_exec_path)"))
                goto close_prog_rmdir;

        if (!check_syscall_operations(bpf_map__fd(skel->maps.inode_storage_map),
                                      rm_fd))
                goto close_prog_rmdir;

        /* Sets skel->bss->monitored_pid to the pid of the forked child
         * forks a child process that executes tmp_exec_path and tries to
         * unlink its executable. This operation should be denied by the loaded
         * LSM program.
         */
        err = run_self_unlink(skel, tmp_exec_path);
        if (!ASSERT_EQ(err, EPERM, "run_self_unlink"))
                goto close_prog_rmdir;

        /* Set the process being monitored to be the current process */
        skel->bss->monitored_pid = getpid();

        /* Move copy_of_rm to a new location so that it triggers the
         * inode_rename LSM hook with a new_dentry that has a NULL inode ptr.
         */
        snprintf(cmd, sizeof(cmd), "mv %s/copy_of_rm %s/check_null_ptr",
                 tmp_dir_path, tmp_dir_path);
        if (!ASSERT_OK(system(cmd), "system(mv)"))
                goto close_prog_rmdir;

        ASSERT_EQ(skel->data->inode_storage_result, 0, "inode_storage_result");

        serv_sk = start_server(AF_INET6, SOCK_STREAM, NULL, 0, 0);
        if (!ASSERT_GE(serv_sk, 0, "start_server"))
                goto close_prog_rmdir;

        ASSERT_EQ(skel->data->sk_storage_result, 0, "sk_storage_result");

        if (!check_syscall_operations(bpf_map__fd(skel->maps.sk_storage_map),
                                      serv_sk))
                goto close_prog_rmdir;

close_prog_rmdir:
        snprintf(cmd, sizeof(cmd), "rm -rf %s", tmp_dir_path);
        system(cmd);
close_prog:
        close(serv_sk);
        close(rm_fd);
        close(task_fd);
        local_storage__destroy(skel);
}