// SPDX-License-Identifier: GPL-2.0
/*
 * Landlock tests - Signal Scoping
 *
 * Copyright © 2024 Tahera Fahimi <fahimitahera@gmail.com>
 */

#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <linux/landlock.h>
#include <pthread.h>
#include <signal.h>
#include <sys/prctl.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

#include "common.h"
#include "scoped_common.h"

/* This variable is used for handling several signals. */
static volatile sig_atomic_t is_signaled;

/* clang-format off */
FIXTURE(scoping_signals) {};
/* clang-format on */

FIXTURE_VARIANT(scoping_signals)
{
        int sig;
};

/* clang-format off */
FIXTURE_VARIANT_ADD(scoping_signals, sigtrap) {
        /* clang-format on */
        .sig = SIGTRAP,
};

/* clang-format off */
FIXTURE_VARIANT_ADD(scoping_signals, sigurg) {
        /* clang-format on */
        .sig = SIGURG,
};

/* clang-format off */
FIXTURE_VARIANT_ADD(scoping_signals, sighup) {
        /* clang-format on */
        .sig = SIGHUP,
};

/* clang-format off */
FIXTURE_VARIANT_ADD(scoping_signals, sigtstp) {
        /* clang-format on */
        .sig = SIGTSTP,
};

FIXTURE_SETUP(scoping_signals)
{
        drop_caps(_metadata);

        is_signaled = 0;
}

FIXTURE_TEARDOWN(scoping_signals)
{
}

static void scope_signal_handler(int sig, siginfo_t *info, void *ucontext)
{
        if (sig == SIGTRAP || sig == SIGURG || sig == SIGHUP || sig == SIGTSTP)
                is_signaled = 1;
}

/*
 * In this test, a child process sends a signal to parent before and
 * after getting scoped.
 */
TEST_F(scoping_signals, send_sig_to_parent)
{
        int pipe_parent[2];
        int status;
        pid_t child;
        pid_t parent = getpid();
        struct sigaction action = {
                .sa_sigaction = scope_signal_handler,
                .sa_flags = SA_SIGINFO,

        };

        ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC));
        ASSERT_LE(0, sigaction(variant->sig, &action, NULL));

        /* The process should not have already been signaled. */
        EXPECT_EQ(0, is_signaled);

        child = fork();
        ASSERT_LE(0, child);
        if (child == 0) {
                char buf_child;
                int err;

                EXPECT_EQ(0, close(pipe_parent[1]));

                /*
                 * The child process can send signal to parent when
                 * domain is not scoped.
                 */
                err = kill(parent, variant->sig);
                ASSERT_EQ(0, err);
                ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1));
                EXPECT_EQ(0, close(pipe_parent[0]));

                create_scoped_domain(_metadata, LANDLOCK_SCOPE_SIGNAL);

                /*
                 * The child process cannot send signal to the parent
                 * anymore.
                 */
                err = kill(parent, variant->sig);
                ASSERT_EQ(-1, err);
                ASSERT_EQ(EPERM, errno);

                /*
                 * No matter of the domain, a process should be able to
                 * send a signal to itself.
                 */
                ASSERT_EQ(0, is_signaled);
                ASSERT_EQ(0, raise(variant->sig));
                ASSERT_EQ(1, is_signaled);

                _exit(_metadata->exit_code);
                return;
        }
        EXPECT_EQ(0, close(pipe_parent[0]));

        /* Waits for a first signal to be received, without race condition. */
        while (!is_signaled && !usleep(1))
                ;
        ASSERT_EQ(1, is_signaled);
        ASSERT_EQ(1, write(pipe_parent[1], ".", 1));
        EXPECT_EQ(0, close(pipe_parent[1]));
        is_signaled = 0;

        ASSERT_EQ(child, waitpid(child, &status, 0));
        if (WIFSIGNALED(status) || !WIFEXITED(status) ||
            WEXITSTATUS(status) != EXIT_SUCCESS)
                _metadata->exit_code = KSFT_FAIL;

        EXPECT_EQ(0, is_signaled);
}

/* clang-format off */
FIXTURE(scoped_domains) {};
/* clang-format on */

#include "scoped_base_variants.h"

FIXTURE_SETUP(scoped_domains)
{
        drop_caps(_metadata);
}

FIXTURE_TEARDOWN(scoped_domains)
{
}

/*
 * This test ensures that a scoped process cannot send signal out of
 * scoped domain.
 */
TEST_F(scoped_domains, check_access_signal)
{
        pid_t child;
        pid_t parent = getpid();
        int status;
        bool can_signal_child, can_signal_parent;
        int pipe_parent[2], pipe_child[2];
        char buf_parent;
        int err;

        can_signal_parent = !variant->domain_child;
        can_signal_child = !variant->domain_parent;

        if (variant->domain_both)
                create_scoped_domain(_metadata, LANDLOCK_SCOPE_SIGNAL);

        ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC));
        ASSERT_EQ(0, pipe2(pipe_child, O_CLOEXEC));

        child = fork();
        ASSERT_LE(0, child);
        if (child == 0) {
                char buf_child;

                EXPECT_EQ(0, close(pipe_child[0]));
                EXPECT_EQ(0, close(pipe_parent[1]));

                if (variant->domain_child)
                        create_scoped_domain(_metadata, LANDLOCK_SCOPE_SIGNAL);

                ASSERT_EQ(1, write(pipe_child[1], ".", 1));
                EXPECT_EQ(0, close(pipe_child[1]));

                /* Waits for the parent to send signals. */
                ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1));
                EXPECT_EQ(0, close(pipe_parent[0]));

                err = kill(parent, 0);
                if (can_signal_parent) {
                        ASSERT_EQ(0, err);
                } else {
                        ASSERT_EQ(-1, err);
                        ASSERT_EQ(EPERM, errno);
                }
                /*
                 * No matter of the domain, a process should be able to
                 * send a signal to itself.
                 */
                ASSERT_EQ(0, raise(0));

                _exit(_metadata->exit_code);
                return;
        }
        EXPECT_EQ(0, close(pipe_parent[0]));
        EXPECT_EQ(0, close(pipe_child[1]));

        if (variant->domain_parent)
                create_scoped_domain(_metadata, LANDLOCK_SCOPE_SIGNAL);

        ASSERT_EQ(1, read(pipe_child[0], &buf_parent, 1));
        EXPECT_EQ(0, close(pipe_child[0]));

        err = kill(child, 0);
        if (can_signal_child) {
                ASSERT_EQ(0, err);
        } else {
                ASSERT_EQ(-1, err);
                ASSERT_EQ(EPERM, errno);
        }
        ASSERT_EQ(0, raise(0));

        ASSERT_EQ(1, write(pipe_parent[1], ".", 1));
        EXPECT_EQ(0, close(pipe_parent[1]));
        ASSERT_EQ(child, waitpid(child, &status, 0));

        if (WIFSIGNALED(status) || !WIFEXITED(status) ||
            WEXITSTATUS(status) != EXIT_SUCCESS)
                _metadata->exit_code = KSFT_FAIL;
}

enum thread_return {
        THREAD_INVALID = 0,
        THREAD_SUCCESS = 1,
        THREAD_ERROR = 2,
        THREAD_TEST_FAILED = 3,
};

static void *thread_sync(void *arg)
{
        const int pipe_read = *(int *)arg;
        char buf;

        if (read(pipe_read, &buf, 1) != 1)
                return (void *)THREAD_ERROR;

        return (void *)THREAD_SUCCESS;
}

TEST(signal_scoping_thread_before)
{
        pthread_t no_sandbox_thread;
        enum thread_return ret = THREAD_INVALID;
        int thread_pipe[2];

        drop_caps(_metadata);
        ASSERT_EQ(0, pipe2(thread_pipe, O_CLOEXEC));

        ASSERT_EQ(0, pthread_create(&no_sandbox_thread, NULL, thread_sync,
                                    &thread_pipe[0]));

        /* Enforces restriction after creating the thread. */
        create_scoped_domain(_metadata, LANDLOCK_SCOPE_SIGNAL);

        EXPECT_EQ(0, pthread_kill(no_sandbox_thread, 0));
        EXPECT_EQ(1, write(thread_pipe[1], ".", 1));

        EXPECT_EQ(0, pthread_join(no_sandbox_thread, (void **)&ret));
        EXPECT_EQ(THREAD_SUCCESS, ret);

        EXPECT_EQ(0, close(thread_pipe[0]));
        EXPECT_EQ(0, close(thread_pipe[1]));
}

TEST(signal_scoping_thread_after)
{
        pthread_t scoped_thread;
        enum thread_return ret = THREAD_INVALID;
        int thread_pipe[2];

        drop_caps(_metadata);
        ASSERT_EQ(0, pipe2(thread_pipe, O_CLOEXEC));

        /* Enforces restriction before creating the thread. */
        create_scoped_domain(_metadata, LANDLOCK_SCOPE_SIGNAL);

        ASSERT_EQ(0, pthread_create(&scoped_thread, NULL, thread_sync,
                                    &thread_pipe[0]));

        EXPECT_EQ(0, pthread_kill(scoped_thread, 0));
        EXPECT_EQ(1, write(thread_pipe[1], ".", 1));

        EXPECT_EQ(0, pthread_join(scoped_thread, (void **)&ret));
        EXPECT_EQ(THREAD_SUCCESS, ret);

        EXPECT_EQ(0, close(thread_pipe[0]));
        EXPECT_EQ(0, close(thread_pipe[1]));
}

struct thread_setuid_args {
        int pipe_read, new_uid;
};

void *thread_setuid(void *ptr)
{
        const struct thread_setuid_args *arg = ptr;
        char buf;

        if (read(arg->pipe_read, &buf, 1) != 1)
                return (void *)THREAD_ERROR;

        /* libc's setuid() should update all thread's credentials. */
        if (getuid() != arg->new_uid)
                return (void *)THREAD_TEST_FAILED;

        return (void *)THREAD_SUCCESS;
}

TEST(signal_scoping_thread_setuid)
{
        struct thread_setuid_args arg;
        pthread_t no_sandbox_thread;
        enum thread_return ret = THREAD_INVALID;
        int pipe_parent[2];
        int prev_uid;

        disable_caps(_metadata);

        /* This test does not need to be run as root. */
        prev_uid = getuid();
        arg.new_uid = prev_uid + 1;
        EXPECT_LT(0, arg.new_uid);

        ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC));
        arg.pipe_read = pipe_parent[0];

        /* Capabilities must be set before creating a new thread. */
        set_cap(_metadata, CAP_SETUID);
        ASSERT_EQ(0, pthread_create(&no_sandbox_thread, NULL, thread_setuid,
                                    &arg));

        /* Enforces restriction after creating the thread. */
        create_scoped_domain(_metadata, LANDLOCK_SCOPE_SIGNAL);

        EXPECT_NE(arg.new_uid, getuid());
        EXPECT_EQ(0, setuid(arg.new_uid));
        EXPECT_EQ(arg.new_uid, getuid());
        EXPECT_EQ(1, write(pipe_parent[1], ".", 1));

        EXPECT_EQ(0, pthread_join(no_sandbox_thread, (void **)&ret));
        EXPECT_EQ(THREAD_SUCCESS, ret);

        clear_cap(_metadata, CAP_SETUID);
        EXPECT_EQ(0, close(pipe_parent[0]));
        EXPECT_EQ(0, close(pipe_parent[1]));
}

const short backlog = 10;

static volatile sig_atomic_t signal_received;

static void handle_sigurg(int sig)
{
        if (sig == SIGURG)
                signal_received = 1;
        else
                signal_received = -1;
}

static int setup_signal_handler(int signal)
{
        struct sigaction sa = {
                .sa_handler = handle_sigurg,
        };

        if (sigemptyset(&sa.sa_mask))
                return -1;

        sa.sa_flags = SA_SIGINFO | SA_RESTART;
        return sigaction(SIGURG, &sa, NULL);
}

/* clang-format off */
FIXTURE(fown) {};
/* clang-format on */

enum fown_sandbox {
        SANDBOX_NONE,
        SANDBOX_BEFORE_FORK,
        SANDBOX_BEFORE_SETOWN,
        SANDBOX_AFTER_SETOWN,
};

FIXTURE_VARIANT(fown)
{
        const enum fown_sandbox sandbox_setown;
};

/* clang-format off */
FIXTURE_VARIANT_ADD(fown, no_sandbox) {
        /* clang-format on */
        .sandbox_setown = SANDBOX_NONE,
};

/* clang-format off */
FIXTURE_VARIANT_ADD(fown, sandbox_before_fork) {
        /* clang-format on */
        .sandbox_setown = SANDBOX_BEFORE_FORK,
};

/* clang-format off */
FIXTURE_VARIANT_ADD(fown, sandbox_before_setown) {
        /* clang-format on */
        .sandbox_setown = SANDBOX_BEFORE_SETOWN,
};

/* clang-format off */
FIXTURE_VARIANT_ADD(fown, sandbox_after_setown) {
        /* clang-format on */
        .sandbox_setown = SANDBOX_AFTER_SETOWN,
};

FIXTURE_SETUP(fown)
{
        drop_caps(_metadata);
}

FIXTURE_TEARDOWN(fown)
{
}

/*
 * Sending an out of bound message will trigger the SIGURG signal
 * through file_send_sigiotask.
 */
TEST_F(fown, sigurg_socket)
{
        int server_socket, recv_socket;
        struct service_fixture server_address;
        char buffer_parent;
        int status;
        int pipe_parent[2], pipe_child[2];
        pid_t child;

        memset(&server_address, 0, sizeof(server_address));
        set_unix_address(&server_address, 0);

        ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC));
        ASSERT_EQ(0, pipe2(pipe_child, O_CLOEXEC));

        if (variant->sandbox_setown == SANDBOX_BEFORE_FORK)
                create_scoped_domain(_metadata, LANDLOCK_SCOPE_SIGNAL);

        child = fork();
        ASSERT_LE(0, child);
        if (child == 0) {
                int client_socket;
                char buffer_child;

                EXPECT_EQ(0, close(pipe_parent[1]));
                EXPECT_EQ(0, close(pipe_child[0]));

                ASSERT_EQ(0, setup_signal_handler(SIGURG));
                client_socket = socket(AF_UNIX, SOCK_STREAM, 0);
                ASSERT_LE(0, client_socket);

                /* Waits for the parent to listen. */
                ASSERT_EQ(1, read(pipe_parent[0], &buffer_child, 1));
                ASSERT_EQ(0, connect(client_socket, &server_address.unix_addr,
                                     server_address.unix_addr_len));

                /*
                 * Waits for the parent to accept the connection, sandbox
                 * itself, and call fcntl(2).
                 */
                ASSERT_EQ(1, read(pipe_parent[0], &buffer_child, 1));
                /* May signal itself. */
                ASSERT_EQ(1, send(client_socket, ".", 1, MSG_OOB));
                EXPECT_EQ(0, close(client_socket));
                ASSERT_EQ(1, write(pipe_child[1], ".", 1));
                EXPECT_EQ(0, close(pipe_child[1]));

                /* Waits for the message to be received. */
                ASSERT_EQ(1, read(pipe_parent[0], &buffer_child, 1));
                EXPECT_EQ(0, close(pipe_parent[0]));

                if (variant->sandbox_setown == SANDBOX_BEFORE_SETOWN) {
                        ASSERT_EQ(0, signal_received);
                } else {
                        /*
                         * A signal is only received if fcntl(F_SETOWN) was
                         * called before any sandboxing or if the signal
                         * receiver is in the same domain.
                         */
                        ASSERT_EQ(1, signal_received);
                }
                _exit(_metadata->exit_code);
                return;
        }
        EXPECT_EQ(0, close(pipe_parent[0]));
        EXPECT_EQ(0, close(pipe_child[1]));

        server_socket = socket(AF_UNIX, SOCK_STREAM, 0);
        ASSERT_LE(0, server_socket);
        ASSERT_EQ(0, bind(server_socket, &server_address.unix_addr,
                          server_address.unix_addr_len));
        ASSERT_EQ(0, listen(server_socket, backlog));
        ASSERT_EQ(1, write(pipe_parent[1], ".", 1));

        recv_socket = accept(server_socket, NULL, NULL);
        ASSERT_LE(0, recv_socket);

        if (variant->sandbox_setown == SANDBOX_BEFORE_SETOWN)
                create_scoped_domain(_metadata, LANDLOCK_SCOPE_SIGNAL);

        /*
         * Sets the child to receive SIGURG for MSG_OOB.  This uncommon use is
         * a valid attack scenario which also simplifies this test.
         */
        ASSERT_EQ(0, fcntl(recv_socket, F_SETOWN, child));

        if (variant->sandbox_setown == SANDBOX_AFTER_SETOWN)
                create_scoped_domain(_metadata, LANDLOCK_SCOPE_SIGNAL);

        ASSERT_EQ(1, write(pipe_parent[1], ".", 1));

        /* Waits for the child to send MSG_OOB. */
        ASSERT_EQ(1, read(pipe_child[0], &buffer_parent, 1));
        EXPECT_EQ(0, close(pipe_child[0]));
        ASSERT_EQ(1, recv(recv_socket, &buffer_parent, 1, MSG_OOB));
        EXPECT_EQ(0, close(recv_socket));
        EXPECT_EQ(0, close(server_socket));
        ASSERT_EQ(1, write(pipe_parent[1], ".", 1));
        EXPECT_EQ(0, close(pipe_parent[1]));

        ASSERT_EQ(child, waitpid(child, &status, 0));
        if (WIFSIGNALED(status) || !WIFEXITED(status) ||
            WEXITSTATUS(status) != EXIT_SUCCESS)
                _metadata->exit_code = KSFT_FAIL;
}

TEST_HARNESS_MAIN